U.S. patent application number 17/492989 was filed with the patent office on 2022-01-27 for surface-reacted calcium carbonate with functional cations.
The applicant listed for this patent is OMYA INTERNATIONAL AG. Invention is credited to Patrick A. C. GANE, Daniel E. GERARD, Joachim GLAUBITZ, Martina Elisabeth KNUPFER, Samuel RENTSCH, Simon URWYLER, Matthias WELKER.
Application Number | 20220025189 17/492989 |
Document ID | / |
Family ID | |
Filed Date | 2022-01-27 |
United States Patent
Application |
20220025189 |
Kind Code |
A1 |
GERARD; Daniel E. ; et
al. |
January 27, 2022 |
SURFACE-REACTED CALCIUM CARBONATE WITH FUNCTIONAL CATIONS
Abstract
A method of preserving, controlling an odor, and/or enhancing
and/or mediating antimicrobial activity of a substrate is
described, the method comprising administering a surface-reacted
calcium carbonate. The surface-reacted calcium carbonate is
obtained by a process comprising treating a calcium
carbonate-comprising material with at least one H.sub.3O.sup.+ ion
donor, carbon dioxide, and at least one water-soluble metal cation
source in an aqueous medium to form an aqueous suspension of
surface-reacted calcium carbonate.
Inventors: |
GERARD; Daniel E.; (Basel,
CH) ; RENTSCH; Samuel; (Spiegel bei Bern, CH)
; WELKER; Matthias; (Hesingue, FR) ; URWYLER;
Simon; (Bern, CH) ; GLAUBITZ; Joachim;
(Pfaffnau, CH) ; KNUPFER; Martina Elisabeth;
(Rotkreuz, CH) ; GANE; Patrick A. C.; (Rothrist,
CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OMYA INTERNATIONAL AG |
Oftringen |
|
CH |
|
|
Appl. No.: |
17/492989 |
Filed: |
October 4, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16320654 |
Jan 25, 2019 |
11168219 |
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PCT/EP2017/068359 |
Jul 20, 2017 |
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17492989 |
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62369291 |
Aug 1, 2016 |
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International
Class: |
C09C 1/02 20060101
C09C001/02; D21H 17/67 20060101 D21H017/67; D21H 19/38 20060101
D21H019/38; D21H 21/52 20060101 D21H021/52 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 25, 2016 |
EP |
16181085.8 |
Claims
1. A method of preserving, controlling an odor, and/or enhancing
and/or mediating antimicrobial activity of a substrate, the method
comprising administering a surface-reacted calcium carbonate in an
amount sufficient to act as a preservative, to control the odor
and/or enhance and/or mediate the antimicrobial activity of the
substrate, wherein the surface-reacted calcium carbonate is
obtained by a process comprising the steps of: a) providing a
calcium carbonate-comprising material, wherein the calcium
carbonate-comprising material is a natural ground calcium
carbonate, b) providing at least one H.sub.3O.sup.+ ion donor,
wherein the at least one H.sub.3O.sup.+ ion donor is phosphoric
acid, c) providing at least one water-soluble metal cation source,
and d) treating the calcium carbonate-comprising material of step
a) with the at least one H.sub.30.sup.+ ion donor of step b) and
carbon dioxide in an aqueous medium to form an aqueous suspension
of surface-reacted calcium carbonate, wherein in step d) the
calcium carbonate-comprising material is treated with a solution
comprising the at least one H.sub.3O.sup.+ ion donor of step b) and
the at least one water-soluble metal cation source of step c),
wherein the at least one water-soluble metal cation source is
selected from the group consisting of copper nitrate, copper
sulphate, copper acetate, copper chloride, copper bromide, copper
iodide, zinc nitrate, zinc sulphate, zinc acetate, zinc chloride,
zinc bromide, zinc iodide, hydrates thereof, and mixtures thereof,
wherein the carbon dioxide is formed in-situ by the H.sub.3O.sup.+
ion donor treatment of the calcium carbonate-comprising material
and/or is supplied from an external source, and wherein the at
least one water-soluble metal cation source of step c) is added
during step d).
2. (canceled)
3. The method of claim 1, wherein the calcium carbonate-comprising
material is in the form of particles having a weight median
particle size d.sub.50(wt) from 0.05 .mu.m to 10 .mu.m and/or a
weight top cut particle size d.sub.98(wt) from 0.15 .mu.m to 55
.mu.m.
4. (canceled)
5. The method of claim 1, wherein the molar ratio of the at least
one H.sub.3O.sup.+ ion donor to the calcium carbonate-comprising
material is from 0.01 to 4.
6. (canceled)
7. The method of claim 1, wherein the at least one water-soluble
metal cation source is provided in an amount from 0.01 wt.-% to 60
wt.-%, based on the total weight of the calcium
carbonate-comprising material.
8. (canceled)
9. The method of claim 1, wherein in step d) the calcium
carbonate-comprising material is treated with a first solution
comprising a first part of the at least one H.sub.3O.sup.+ ion
donor of step b), and subsequently, with a second solution
comprising the remaining part of the at least one H.sub.3O.sup.+
ion donor of step b) and the at least one water-soluble metal
cation source of step c).
10. The method of claim 1, wherein step d) is carried out at a
temperature from 20.degree. C. to 90.degree. C.
11. The method of claim 1, wherein the process further comprises a
step e) of separating the surface-reacted calcium carbonate from
the aqueous suspension obtained in step d).
12. The method of claim 1, wherein the process further comprises a
step f) of drying the surface-reacted calcium carbonate after step
d) at a temperature in the range from 60.degree. C.
13. (canceled)
14. (canceled)
15. The method of claim 1, wherein the surface-reacted calcium
carbonate has a specific surface area of from 15 m.sup.2/g to 200
m.sup.2/g measured using nitrogen and the BET method.
16. The method of claim 1, wherein the surface-reacted calcium
carbonate has a volume determined median particle size
d.sub.50(vol) from 1 .mu.m to 75 .mu.m and/or a volume determined
top cut particle size d.sub.98(vol) from 2 .mu.m to 150 .mu.m.
17. The method of claim 1, wherein the surface-reacted calcium
carbonate has an intra-particle intruded specific pore volume in
the range from 0.1 cm.sup.3/g to 2.3 cm.sup.3/g calculated from
mercury porosimetry measurement.
18. The method of claim 1, wherein the surface-reacted calcium
carbonate has an intra-particle pore size in a range of from 0.004
.mu.m to 1.6 .mu.m determined from mercury porosity
measurement.
19. The method of claim 1, wherein the administering a
surface-reacted calcium carbonate comprises administering a
composition comprising the surface-reacted calcium carbonate and an
additional surface-reacted calcium carbonate, wherein the
additional surface-reacted calcium carbonate is a reaction product
of natural ground calcium carbonate or precipitated calcium
carbonate with carbon dioxide and at least one H.sub.3O.sup.+ ion
donor, wherein the carbon dioxide is formed in-situ by the
H.sub.3O.sup.+ ion donor treatment and/or is supplied from an
external source.
20-23. (canceled)
24. The method according to claim 1, wherein the substrate is
selected from the group consisting of paper products, engineered
wood products, plasterboard products, polymer products, hygiene
products, medical products, healthcare products, filter products,
woven materials, nonwoven materials, geotextile products,
agriculture products, horticulture products, clothing, footwear
products, baggage products, household products, industrial
products, packaging products, building products, and construction
products.
25. The method of claim 2, wherein the natural ground calcium
carbonate is selected from the group consisting of marble, chalk,
dolomite, limestone, and mixtures thereof.
26. The method of claim 3, wherein the weight median particle size
d.sub.50(wt) is from 0.2 .mu.m to 5.0 .mu.m and/or the weight top
cut particle size d.sub.98(wt) is from 1 .mu.m to 40 .mu.m.
27. The method of claim 5, wherein the molar ratio is from 0.02 to
2.
28. The method of claim 7, wherein the amount of the at least one
water-soluble metal cation source is from 0.05 wt.-% to 50
wt.-%.
29. The method of claim 12, wherein the drying is conducted until
the moisture content of the surface-reacted calcium carbonate is
from 0.01 wt.-% to 5 wt.-% based on the total weight of the dried
surface-reacted calcium carbonate.
30. The method of claim 15, wherein the specific surface area is
from 20 m.sup.2/g to 180 m.sup.2/g.
31. The method of claim 16, wherein the volume determined median
particle size d.sub.50(vol) is from 2 .mu.m to 50 .mu.m and/or the
volume determined top cut particle size d.sub.98(vol) is from 4
.mu.m to 100 .mu.m.
32. The method of claim 17, wherein the intra-particle intruded
specific pore volume is from 0.2 cm.sup.2/g to 2.0 cm.sup.3/g.
33. The method of claim 18, wherein the intra-particle pore size is
from 0.005 .mu.m to 1.3 .mu.m.
34. The method of claim 1, wherein the method comprises
administering the surface-reacted calcium carbonate in an amount
sufficient to act as a preservative of the substrate.
35. The method of claim 1, wherein the method comprises
administering the surface-reacted calcium carbonate in an amount
sufficient to control the odor of the substrate.
36. The method of claim 35, wherein the odor originates from an
odorant selected from the group consisting of odorants contained in
a human or animal body liquid or secretions, odorants originating
from putrefaction, and odorants contained in food.
37. The method of claim 35, wherein the odor originates from an
odorant selected from the group consisting of: a) an odorant
originating from putrefaction of human or animal tissue; b) an
odorant contained in a human or animal body liquid or secretion
selected from the group consisting of menses, blood, plasma,
sanies, vaginal secretions, mucus, milk, urine, feces, vomit and
perspiration; and c) an odorant in a food selected from the group
consisting of dairy products, meat, fish and fruit.
38. The method of claim 1, wherein the method comprises
administering the surface-reacted calcium carbonate in an amount
sufficient to enhance and/or mediate the antimicrobial activity of
the substrate.
39. The method of claim 38, wherein the substrate is selected from
the group consisting of a sheet of paper, a cardboard, a polymer
material, a paint, a wood surface, concrete, and a plant.
40. The method of claim 38, wherein the antimicrobial activity is
against a microorganism selected from the group consisting of
bacteria, mold, yeast, and algae.
41. The method of claim 40, wherein the antimicrobial activity is
against a bacteria.
42. The method of claim 41, wherein the bacteria is selected from
the group consisting of Escherichia sp., Staphylococcus sp.,
Thermus sp., Propionibacterium sp., Rhodococcus sp., Panninobacter
sp., Caulobacter sp., Brevundimonas sp., Asticcacaulis sp.,
Sphingomonas sp., Rhizobium sp., Ensifer sp., Bradyrhizobium sp.,
Tepidimonas sp., Tepidicella sp., Aquabacterium sp., Pelomonas sp.,
Alcaligenis sp., Achromobacter sp., Ralstonia sp., Limnobacter sp.,
Massilia sp., Hydrogenophaga sp., Acidovorax sp., Curvibacter sp.,
Delftia sp., Rhodoferax sp., Alishewanella sp., Stenotrophomonas
sp., Dokdonella sp., Methylosinus sp., Hyphomicrobium sp.,
Methylosulfomonas sp., Methylobacteria sp., Pseudomonas sp.,
Enterococcus sp., Myroides sp., Burkholderia sp., Alcaligenes sp.
Staphylococcus sp., and mixtures thereof.
43. The method of claim 42, wherein the bacteria is Staphylococcus
sp.
Description
[0001] The present invention relates to a surface-reacted calcium
carbonate, a process for manufacturing the same, and its use.
[0002] In the year of 1998, a new type of surface-reacted calcium
carbonate was first described in FR 2787802 B1, subsequently in WO
00/39222 A1 and US 2004/0020410 A1, and is based on the reaction of
natural ground calcium carbonate with gaseous CO.sub.2 and with one
or more medium-strong to strong H.sub.3O.sup.+ ion providers. The
obtained product is a porous calcium carbonate having a special
surface structure, porosity, and specific surface area providing a
reduction in the weight of paper for a constant surface area
without loss of physical properties, when it is used as a pigment
or coating filler for the said paper.
[0003] In WO 2004/083316 A1, a further advantageous modification in
the preparation of this surface-reacted calcium carbonate is
described, wherein aluminium silicate, synthetic silica, calcium
silicate, silicates and/or monovalent salt are involved, and which
are also useful in paper-making applications.
[0004] Also, WO 2005/121257 A2 refers to the addition of
advantageous additives in the production of said surface-reacted
calcium carbonate, wherein one or more compounds of formula R--X
are added, which, e.g. are selected from fatty acids, fatty amines
or fatty alcohols.
[0005] WO 2009/074492 A1 especially relates to the optimization of
the known process as regards precipitated calcium carbonate, as it
turned out that due to the special conditions in the precipitation
of calcium carbonate, the process useful for natural ground calcium
carbonate did not provide the same good results for the
surface-reaction of synthetic precipitated calcium carbonate.
[0006] Several further optimizations and modifications of the
process for the preparation of surface-reacted calcium carbonate
followed such as those described in WO 2010/146530 A1 and WO
2010/146531 A1 involving the use of weak acids in the preparation
of surface-reacted calcium carbonate.
[0007] EP 2 957 603 A1 describes a method for producing granules
comprising surface-reacted calcium carbonate.
[0008] The characteristics of these particulate materials may be
further improved or modified by additional surface-treatments, for
example, in order to improve hydrophobicity/hydrophilicity or
acid-resistance. Another aim is to locate surface-treatment agents
on the surface of these particulate materials in order to use them
as carrier material.
[0009] For example, EP 1 084 203 refers to composite compositions
comprising at least two mineral or organic fillers or pigments and
at least one binding agent. The mineral or organic fillers or
pigments have undergone a physical or chemical treatment such that
they have at least one organophilic site.
[0010] EP 2 029 675 refers to composites of inorganic and/or
organic microparticles and nano-calcium carbonate particles. The
surface of these particulate materials is coated with the help of
binders.
[0011] US 2012/0202684 relates to high surface area materials, such
as nanoparticles, which are coated with metal ions by absorbing the
metal ions on the surface of the nanoparticles. The obtained
modified particles can be used for removing gaseous compounds or
for neutralizing odour.
[0012] However, there is still a need in the art for methods for
producing surface-reacted calcium carbonate, and, in particular,
modified surface-reacted calcium carbonate, which provides
additional functionalities.
[0013] Aqueous preparations, for example, and especially
suspensions, dispersions or slurries of minerals, fillers or
pigments, which are used extensively in the paper, paint, rubber
and plastics industries as coatings, fillers, extenders and
pigments for papermaking as well as aqueous lacquers and paints are
often subject to microbial contamination. Such a contamination can
result in changes in the preparation properties such as changes in
viscosity and/or pH, discolorations or reductions in other quality
parameters, which negatively affect their commercial value. The
contaminated filler aqueous preparations may also transmit the
microorganisms to the later produced product, for example, the
plastic or paper product. Therefore, for ensuring an acceptable
microbiological quality of aqueous preparations, preservatives or
biocides are used over the entire life cycle of the preparation
(production, storage, transport, use).
[0014] Preservatives are also typically added to pharmaceutical,
cosmetic or food products to prevent decomposition by microbial
growth or by undesirable chemical changes and to avoid any health
hazards. However, many of these preservatives are themselves
subject to health concerns, and thus, are increasingly rejected by
consumers.
[0015] Dry film preservation, meaning preservation of dry products
such as coatings and building materials from microbiological
degradation to avoid material destruction and visible
disfigurement, is also an important and difficult challenge.
Preservatives for dry film preservation are typically incorporated
in the product and preserve the dry product over a longer period of
time by an antimicrobial activity on the dry or wet surface. Such
an antimicrobial surface activity is of advantage not only to
protect the product itself from degradation or defacement but also
to avoid contamination of a surface with pathogenic microorganisms.
This is particular useful in the health care sector. However, there
is the risk that preservatives are eluted from the dry product over
time, for example, due to rain or humid environment, which may pose
a danger to human health and the environment.
[0016] US 2006/0246149 A1 describes antimicrobial pigments, which
are obtainable by agitating a suspension comprising one or more
pigments and silver oxide as antimicrobial compound. A modified
mineral-based filler with enhanced retention of at least one active
ingredient or enhanced antimicrobial capabilities is disclosed in
US 2010/0260866. A study concerning copper precipitation from
sulphate solutions with calcium carbonate was published by Zhizhaev
et al. (Russian Journal of Applied Chemistry 2007, 80(10),
1632-1635).
[0017] However, there is still a need in the art for harmless
materials with antimicrobial activity, which are suitable for a
wide range of applications.
[0018] Accordingly, it is an object of the present invention to
provide a process for producing a surface-reacted calcium carbonate
which provides further functionalities. It is desirable that the
obtained surface-reacted calcium carbonate can be used as filler
material so that it may replace conventionally used fillers in
various applications or supplement them.
[0019] It is also an object of the present invention to provide a
material, which is at least partially derivable from natural
sources and is not persistent in the environment, but easily
biodegradable. It would also be desirable that said material is
water-resistant, and thus, can be used in application subjected to
regular water washings. It is also desirable that the functionality
of the surface-reacted calcium carbonate can be controlled and can
be tailored for a specific application.
[0020] It is also an object of the present invention to provide a
material which can control microbial contamination but does not
represent a hazard to health. It is a further object of the present
invention to provide a material which, besides the antimicrobial
activity, has additional benefits. For example, it would be
desirable that such a material confers or enhances the
antimicrobial activity of a product, in which it is incorporated,
over an extended period without affecting the properties of the
product in a negative way. It would also be desirable to provide a
material that is suitable for agricultural applications and can
release micronutrients to plants.
[0021] The foregoing and other objects are solved by the
subject-matter as defined in the independent claims.
[0022] According to one aspect of the present invention, a process
for producing a surface-reacted calcium carbonate is provided, the
process comprising the steps of: [0023] a) providing a calcium
carbonate-comprising material, [0024] b) providing at least one
H.sub.3O.sup.+ ion donor, [0025] c) providing at least one
water-soluble metal cation source, and [0026] d) treating the
calcium carbonate-comprising material of step a) with the at least
one H.sub.3O.sup.+ ion donor of step b) and carbon dioxide in an
aqueous medium to form an aqueous suspension of surface-reacted
calcium carbonate, [0027] wherein the carbon dioxide is formed
in-situ by the H.sub.3O.sup.+ ion donor treatment and/or is
supplied from an external source, and [0028] wherein the at least
one water-soluble metal cation source of step c) is added during
step d).
[0029] According to a further aspect, a surface-reacted calcium
carbonate obtainable by a process according to the present
invention is provided.
[0030] According to still a further aspect, a composition
comprising a surface-reacted calcium carbonate according to the
present invention is provided, preferably further comprising an
additional surface-reacted calcium carbonate, wherein the
additional surface-reacted calcium carbonate is a reaction product
of natural ground calcium carbonate or precipitated calcium
carbonate with carbon dioxide and at least one H.sub.3O.sup.+ ion
donor, wherein the carbon dioxide is formed in-situ by the
H.sub.3O.sup.+ ion donor treatment and/or is supplied from an
external source.
[0031] According to still a further aspect, a use of a
surface-reacted calcium carbonate according to the present
invention or a composition according to the present invention as
preservative, for the control of odour, and/or for enhancing and/or
mediating antimicrobial activity of a substrate is provided.
[0032] According to still a further aspect, a use of a
surface-reacted calcium carbonate according to the present
invention or a composition according to the present invention as a
metal cation releaser, preferably as micronutrient delivery agent
and/or plant protection product is provided.
[0033] According to still a further aspect, a use of a
surface-reacted calcium carbonate according to the present
invention or a composition according to the present invention for
enhancing the electrical conductivity of a substrate is
provided.
[0034] According to still a further aspect, use of a
surface-reacted calcium carbonate according to the present
invention or a composition according to the present invention in
polymer applications, paper coating applications, paper making,
paints, coatings, sealants, printing inks, adhesives, food, feed,
pharmaceuticals, concrete, cement, cosmetics, water treatment,
engineered wood applications, plasterboard applications, packaging
applications and/or agricultural applications is provided.
[0035] According to still a further aspect, an article comprising a
surface-reacted calcium carbonate according to the present
invention or a composition according to the present invention is
provided, wherein the article is selected from paper products,
engineered wood products, plasterboard products, polymer products,
hygiene products, medical products, healthcare products, filter
products, woven materials, nonwoven materials, geotextile products,
agricultural products, horticultural products, clothing, footwear
products, baggage products, household products, industrial
products, packaging products, building products, and construction
products.
[0036] Advantageous embodiments of the present invention are
defined in the corresponding subclaims.
[0037] According to one embodiment the calcium carbonate-comprising
material is a natural ground calcium carbonate and/or a
precipitated calcium carbonate, preferably the natural ground
calcium carbonate is selected from the group consisting of marble,
chalk, dolomite, limestone, and mixtures thereof, and/or the
precipitated calcium carbonate is selected from the group
consisting of precipitated calcium carbonates having an aragonitic,
vateritic or calcitic crystal form, and mixtures thereof. According
to a further embodiment the calcium carbonate-comprising material
is in form of particles having a weight median particle size
d.sub.50(wt) from 0.05 to 10 .mu.m, preferably from 0.2 to 5.0
.mu.m, more preferably from 0.4 to 3.0 .mu.m, and most preferably
from 0.6 to 1.2 .mu.m, and/or a weight top cut particle size
d.sub.98(wt) from 0.15 to 55 .mu.m, preferably from 1 to 40 .mu.m,
more preferably from 2 to 25 .mu.m, and most preferably from 3 to
15 .mu.m.
[0038] According to one embodiment the at least one H.sub.3O.sup.+
ion donor is selected from the group consisting of hydrochloric
acid, sulphuric acid, sulphurous acid, phosphoric acid, citric
acid, oxalic acid, an acidic salt, acetic acid, formic acid, and
mixtures thereof, preferably the at least one H.sub.3O.sup.+ ion
donor is selected from the group consisting of hydrochloric acid,
sulphuric acid, sulphurous acid, phosphoric acid, oxalic acid,
H.sub.2PO.sub.4.sup.-, being at least partially neutralised by a
cation selected from Li.sup.+, Na.sup.+ and/or K.sup.+,
HPO.sub.4.sup.2-, being at least partially neutralised by a cation
selected from Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.2+, and/or
Ca.sup.2+, and mixtures thereof, more preferably the at least one
H.sub.3O.sup.+ ion donor is selected from the group consisting of
hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric
acid, oxalic acid, or mixtures thereof, and most preferably, the at
least one H.sub.3O.sup.+ ion donor is phosphoric acid. According to
a further embodiment the molar ratio of the at least one
H.sub.3O.sup.+ ion donor to the calcium carbonate-comprising
material is from 0.01 to 4, preferably from 0.02 to 2, more
preferably from 0.05 to 1, and most preferably from 0.1 to
0.58.
[0039] According to one embodiment the at least one water-soluble
metal cation source is selected from the group consisting of a
water-soluble metal salt, a water-soluble transition metal complex,
a water-soluble metal hydroxide, a water-soluble metal oxide, and
mixtures thereof, preferably the water-soluble metal cation source
is selected from the group consisting of a water-soluble transition
metal salt, a water-soluble group(III) metal salt, and mixtures
thereof, more preferably the water-soluble metal cation source is
selected from the group consisting of water-soluble salts of
aluminium, chromium, manganese, iron, cobalt, nickel, copper, zinc,
silver, gold, zirconium, platinum, palladium, and mixtures thereof,
and most preferably the water-soluble metal cation source is
selected from the group consisting of copper nitrate, copper
sulphate, copper acetate, copper chloride, copper bromide, copper
iodide, zinc nitrate, zinc sulphate, zinc acetate, zinc chloride,
zinc bromide, zinc iodide, hydrates thereof, and mixtures thereof.
According to a further embodiment the at least one water-soluble
metal cation source is provided in an amount from 0.01 to 60 wt.-%,
based on the total weight of the calcium carbonate-comprising
material, preferably from 0.05 to 50 wt.-%, more preferably from
0.1 to 25 wt.-%, and most preferably from 0.5 to 10 wt.-%.
[0040] According to one embodiment in step d) the calcium
carbonate-comprising material is treated with a solution comprising
the at least one H.sub.3O.sup.+ ion donor of step b) and the at
least one water-soluble metal cation source of step c). According
to a further embodiment in step d) the calcium carbonate-comprising
material is treated with a first solution comprising a first part
of the at least one H.sub.3O.sup.+ ion donor of step b), and
subsequently, with a second solution comprising the remaining part
of the at least one H.sub.3O.sup.+ ion donor of step b) and the at
least one water-soluble metal cation source of step c). According
to still a further embodiment step d) is carried out at a
temperature from 20 to 90.degree. C., preferably from 30 to
85.degree. C., more preferably from 40 to 80.degree. C., even more
preferably from 50 to 75.degree. C., and most preferably from 60 to
70.degree. C.
[0041] According to one embodiment the process further comprises a
step e) of separating the surface-reacted calcium carbonate from
the aqueous suspension obtained in step d). According to a further
embodiment the process further comprises a step f) of drying the
surface-reacted calcium carbonate after step d) or after step c),
if present, at a temperature in the range from 60 to 600.degree.
C., preferably until the moisture content of the surface-reacted
calcium carbonate is between 0.01 and 5 wt.-%, based on the total
weight of the dried surface-reacted calcium carbonate.
[0042] According to one embodiment the calcium carbonate-comprising
material is a natural ground calcium carbonate, the at least one
H.sub.3O.sup.+ ion donor is phosphoric acid, the at least one
water-soluble metal cation source is selected from the group
consisting of copper nitrate, copper sulphate, copper acetate,
copper chloride, copper bromide, copper iodide, zinc nitrate, zinc
sulphate, zinc acetate, zinc chloride, zinc bromide, zinc iodide,
hydrates thereof, and mixtures thereof, and in step d) the calcium
carbonate-comprising material is treated with a solution comprising
the at least one H.sub.3O.sup.+ ion donor of step b) and the at
least one water-soluble metal cation source of step c).
[0043] According to one embodiment the surface-reacted calcium
carbonate has a specific surface area of from 15 m.sup.2/g to 200
m.sup.2/g, preferably from 20 m.sup.2/g to 180 m.sup.2/g, more
preferably from 25 m.sup.2/g to 160 m.sup.2/g, even more preferably
from 27 m.sup.2/g to 150 m.sup.2/g, most preferably from 30
m.sup.2/g to 140 m.sup.2/g, measured using nitrogen and the BET
method. According to a further embodiment the surface-reacted
calcium carbonate has a volume determined median particle size
d.sub.50(vol) from 1 to 75 .mu.m, preferably from 2 to 50 .mu.m,
more preferably from 3 to 40 .mu.m, even more preferably from 4 to
30 .mu.m, and most preferably from 5 to 15 .mu.m, and/or a volume
determined top cut particle size d.sub.98(vol) from 2 to 150 .mu.m,
preferably from 4 to 100 .mu.m, more preferably from 6 to 80 .mu.m,
even more preferably from 8 to 60 .mu.m, and most preferably from
10 to 30 .mu.m.
[0044] According to one embodiment the surface-reacted calcium
carbonate has an intra-particle intruded specific pore volume in
the range from 0.1 to 2.3 cm.sup.3/g, preferably from 0.2 to 2.0
cm.sup.3/g, more preferably from 0.4 to 1.8 cm.sup.3/g, and most
preferably from 0.6 to 1.6 cm.sup.3/g, calculated from mercury
porosimetry measurement. According to a further embodiment the
surface-reacted calcium carbonate has an intra-particle pore size
in a range of from 0.004 to 1.6 .mu.m, preferably in a range of
between 0.005 to 1.3 .mu.m, more preferably from 0.006 to 1.15
.mu.m, and most preferably of 0.007 to 1.0 .mu.m, determined from
mercury porosity measurement.
[0045] It should be understood that for the purpose of the present
invention, the following terms have the following meaning:
[0046] A "calcium carbonate-comprising material" in the meaning of
the present invention can be a mineral material or a synthetic
material having a content of calcium carbonate of at least 50
wt.-%, preferably 75 wt.-%, more preferably 90 wt.-%, and most
preferably 95 wt.-%, based on the total weight of the calcium
carbonate-comprising material.
[0047] For the purpose of the present application,
"water-insoluble" materials are defined as materials which, when
100 g of said material is mixed with 100 g deionised water and
filtered on a filter having a 0.2 .mu.m pore size at 20.degree. C.
to recover the liquid filtrate, provide less than or equal to 1 g
of recovered solid material following evaporation at 95 to
100.degree. C. of 100 g of said liquid filtrate at ambient
pressure. "Water-soluble" materials are defined as materials which,
when 100 g of said material is mixed with 100 g deionised water and
filtered on a filter having a 0.2 .mu.m pore size at 20.degree. C.
to recover the liquid filtrate, provide more than 1 g of recovered
solid material following evaporation at 95 to 100.degree. C. of 100
g of said liquid filtrate at ambient pressure.
[0048] "Natural ground calcium carbonate" (GCC) in the meaning of
the present invention is a calcium carbonate obtained from natural
sources, such as limestone, marble, or chalk, and processed through
a wet and/or dry treatment such as grinding, screening and/or
fractionating, for example, by a cyclone or classifier.
[0049] "Precipitated calcium carbonate" (PCC) in the meaning of the
present invention is a synthesised material, obtained by
precipitation following reaction of carbon dioxide and lime in an
aqueous, semi-dry or humid environment or by precipitation of a
calcium and carbonate ion source in water. PCC may be in the
vateritic, calcitic or aragonitic crystal form. PCCs are described,
for example, in EP 2 447 213 A1, EP 2 524 898 A1, EP 2 371 766 A1,
EP 1 712 597 A1, EP 1 712 523 A1, or WO 2013/142473 A1.
[0050] The term "surface-reacted" in the meaning of the present
application shall be used to indicate that a material has been
subjected to a process comprising partial dissolution of said
material upon acidic treatment (e.g., by use of water-soluble free
acids and/or acidic salts) in aqueous environment followed by a
crystallization process which may occur in the absence or presence
of further crystallization additives. The term "acid" as used
herein refers to an acid in the meaning of the definition by
Bronsted and Lowry (e.g., H.sub.2SO.sub.4, HSO.sub.4.sup.-),
wherein the term "free acid" refers only to those acids being in
the fully protonated form (e.g., H.sub.2SO.sub.4).
[0051] The "particle size" of particulate materials other than
surface-reacted calcium carbonate herein is described by its
distribution of particle sizes d.sub.x. Therein, the value d.sub.x
represents the diameter relative to which x % by weight of the
particles have diameters less than d.sub.x. This means that, for
example, the d.sub.20 value is the particle size at which 20 wt.-%
of all particles are smaller than that particle size. The d.sub.50
value is thus the weight median particle size, i.e. 50 wt.-% of all
particles are smaller than this particle size. For the purpose of
the present invention, the particle size is specified as weight
median particle size d.sub.50(wt.) unless indicated otherwise.
Particle sizes were determined by using a Sedigraph.TM. 5100
instrument or Sedigraph.TM. 5120 instrument of Micromeritics
Instrument Corporation. The method and the instrument are known to
the skilled person and are commonly used to determine the particle
size of fillers and pigments. The measurements were carried out in
an aqueous solution of 0.1 wt.-% Na.sub.4P.sub.2O.sub.7.
[0052] The "particle size" of surface-reacted calcium carbonate
herein is described as volume-based particle size distribution.
Volume-based median particle size d.sub.50 was evaluated using a
Malvern Mastersizer 2000 Laser Diffraction System. The d.sub.50 or
d.sub.98 value, measured using a Malvern Mastersizer 2000 Laser
Diffraction System, indicates a diameter value such that 50% or 98%
by volume, respectively, of the particles have a diameter of less
than this value. The raw data obtained by the measurement are
analysed using the Mie theory, with a particle refractive index of
1.57 and an absorption index of 0.005.
[0053] The "specific surface area" (expressed in m.sup.2/g) of a
material as used throughout the present document can be determined
by the Brunauer Emmett Teller (BET) method with nitrogen as
adsorbing gas and by use of a ASAP 2460 instrument from
Micromeritics. The method is well known to the skilled person and
defined in ISO 9277:2010. Samples are conditioned at 100.degree. C.
under vacuum for a period of 30 min prior to measurement. The total
surface area (in m.sup.2) of said material can be obtained by
multiplication of the specific surface area (in m.sup.2/g) and the
mass (in g) of the material.
[0054] In the context of the present invention, the term "pore" is
to be understood as describing the space that is found between
and/or within particles, i.e. that is formed by the particles as
they pack together under nearest neighbour contact (interparticle
pores), such as in a powder or a compact and/or the void space
within porous particles (intraparticle pores), and that allows the
passage of liquids under pressure when saturated by the liquid
and/or supports absorption of surface wetting liquids.
[0055] The specific pore volume is measured using a mercury
intrusion porosimetry measurement using a Micromeritics Autopore V
9620 mercury porosimeter having a maximum applied pressure of
mercury 414 MPa (60 000 psi), equivalent to a Laplace throat
diameter of 0.004 .mu.m (.about.nm). The equilibration time used at
each pressure step is 20 seconds. The sample material is sealed in
a 3 cm.sup.3 chamber powder penetrometer for analysis. The data are
corrected for mercury compression, penetrometer expansion and
sample material compression using the software Pore-Comp (Gane, P.
A. C., Kettle, J. P., Matthews, G. P. and Ridgway, C. J., "Void
Space Structure of Compressible Polymer Spheres and Consolidated
Calcium Carbonate Paper-Coating Formulations", Industrial and
Engineering Chemistry Research, 35(5), 1996, p 1753-1764).
[0056] The total pore volume seen in the cumulative intrusion data
can be separated into two regions with the intrusion data from 214
.mu.m down to about 1-4 .mu.m showing the coarse packing of the
sample between any agglomerate structures contributing strongly.
Below these diameters lies the fine interparticle packing of the
particles themselves. If they also have intraparticle pores, then
this region appears bi modal, and by taking the specific pore
volume intruded by mercury into pores finer than the modal turning
point, i.e. finer than the bi-modal point of inflection, we thus
define the specific intraparticle pore volume. The sum of these
three regions gives the total overall pore volume of the powder,
but depends strongly on the original sample compaction/settling of
the powder at the coarse pore end of the distribution.
[0057] By taking the first derivative of the cumulative intrusion
curve the pore size distributions based on equivalent Laplace
diameter, inevitably including pore-shielding, are revealed. The
differential curves clearly show the coarse agglomerate pore
structure region, the interparticle pore region and the
intraparticle pore region, if present. Knowing the intraparticle
pore diameter range it is possible to subtract the remainder
interparticle and interagglomerate pore volume from the total pore
volume to deliver the desired pore volume of the internal pores
alone in terms of the pore volume per unit mass (specific pore
volume). The same principle of subtraction, of course, applies for
isolating any of the other pore size regions of interest.
[0058] For the purpose of the present invention, the "solids
content" of a liquid composition is a measure of the amount of
material remaining after all the solvent or water has been
evaporated. If necessary, the "solids content" of a suspension
given in wt.-% in the meaning of the present invention can be
determined using a Moisture Analyzer HR73 from Mettler-Toledo
(T=120.degree. C., automatic switch off 3, standard drying) with a
sample size of 5 to 20 g.
[0059] Unless specified otherwise, the term "drying" refers to a
process according to which at least a portion of water is removed
from a material to be dried such that a constant weight of the
obtained "dried" material at 120.degree. C. is reached. Moreover, a
"dried" or "dry" material may be defined by its total moisture
content which, unless specified otherwise, is less than or equal to
1.0 wt.-%, preferably less than or equal to 0.5 wt.-%, more
preferably less than or equal to 0.2 wt.-%, and most preferably
between 0.03 and 0.07 wt.-%, based on the total weight of the dried
material.
[0060] For the purpose of the present invention, the term
"viscosity" or "Brookfield viscosity" refers to Brookfield
viscosity. The Brookfield viscosity is for this purpose measured by
a Brookfield DV-II+ Pro viscometer at 25.degree. C..+-.1.degree. C.
at 100 rpm using an appropriate spindle of the Brookfield
RV-spindle set and is specified in mPas. Based on his technical
knowledge, the skilled person will select a spindle from the
Brookfield RV-spindle set which is suitable for the viscosity range
to be measured. For example, for a viscosity range between 200 and
800 mPas the spindle number 3 may be used, for a viscosity range
between 400 and 1 600 mPas the spindle number 4 may be used, for a
viscosity range between 800 and 3 200 mPas the spindle number 5 may
be used, for a viscosity range between 1 000 and 2 000 000 mPas the
spindle number 6 may be used, and for a viscosity range between 4
000 and 8 000 000 mPas the spindle number 7 may be used.
[0061] A "suspension" or "slurry" in the meaning of the present
invention comprises undissolved solids and water, and optionally
further additives, and usually contains large amounts of solids
and, thus, is more viscous and can be of higher density than the
liquid from which it is formed.
[0062] Where an indefinite or definite article is used when
referring to a singular noun, e.g., "a", "an" or "the", this
includes a plural of that noun unless anything else is specifically
stated.
[0063] Where the term "comprising" is used in the present
description and claims, it does not exclude other elements. For the
purposes of the present invention, the term "consisting of" is
considered to be a preferred embodiment of the term "comprising".
If hereinafter a group is defined to comprise at least a certain
number of embodiments, this is also to be understood to disclose a
group, which preferably consists only of these embodiments.
[0064] Terms like "obtainable" or "definable" and "obtained" or
"defined" are used interchangeably. This, for example, means that,
unless the context clearly dictates otherwise, the term "obtained"
does not mean to indicate that, for example, an embodiment must be
obtained by, for example, the sequence of steps following the term
"obtained" though such a limited understanding is always included
by the terms "obtained" or "defined" as a preferred embodiment.
[0065] Whenever the terms "including" or "having" are used, these
terms are meant to be equivalent to "comprising" as defined
hereinabove.
[0066] The inventive process for producing a surface-reacted
calcium carbonate comprises the steps of a) providing a calcium
carbonate-comprising material, b) providing at least one
H.sub.3O.sup.+ ion donor, c) providing at least one water-soluble
metal cation source, and d) treating the calcium
carbonate-comprising material of step a) with the at least one
H.sub.3O.sup.+ ion donor of step b) and carbon dioxide in an
aqueous medium to form an aqueous suspension of surface-reacted
calcium carbonate. The carbon dioxide is formed in-situ by the
H.sub.3.sup.+ ion donor treatment and/or is supplied from an
external source. The at least one water-soluble metal cation source
of step c) is added during step d).
[0067] In the following preferred embodiments of the inventive
composition will be set out in more detail. It is to be understood
that these embodiments and details also apply to the inventive
products and uses.
Process Step a)
[0068] According to step a) of the process of the present
invention, a calcium-carbonate comprising material is provided.
[0069] According to one embodiment the at least one calcium
carbonate-comprising material has a content of calcium carbonate of
at least 50 wt.-%, preferably 75 wt.-%, more preferably 90 wt.-%,
and most preferably 95 wt.-%, based on the total weight of the
calcium carbonate-comprising material. According to another
embodiment the at least one calcium carbonate comprising material
consists of calcium carbonate.
[0070] The calcium carbonate-comprising material may be selected
from natural ground calcium carbonate, precipitated calcium
carbonate, dolomite, or mixtures thereof. The natural ground
calcium carbonate may be preferably selected from marble, limestone
and/or chalk, and/or the precipitated calcium carbonate may be
preferably selected from vaterite, calcite and/or aragonite
[0071] According to one embodiment of the present invention, the
calcium carbonate-comprising material is a natural ground calcium
carbonate and/or a precipitated calcium carbonate, preferably the
natural ground calcium carbonate is selected from the group
consisting of marble, chalk, dolomite, limestone, and mixtures
thereof, and/or the precipitated calcium carbonate is selected from
the group consisting of precipitated calcium carbonates having an
aragonitic, vateritic or calcitic crystal form, and mixtures
thereof.
[0072] "Natural ground calcium carbonate" (GCC) is understood to be
manufactured from a naturally occurring form of calcium carbonate,
mined from sedimentary rocks such as limestone or chalk, or from
metamorphic marble rocks, eggshells or seashells. Calcium carbonate
is known to exist as three types of crystal polymorphs: calcite,
aragonite and vaterite. Calcite, the most common crystal polymorph,
is considered to be the most stable crystal form of calcium
carbonate. Less common is aragonite, which has a discrete or
clustered needle orthorhombic crystal structure. Vaterite is the
rarest calcium carbonate polymorph and is generally unstable.
Ground calcium carbonate is almost exclusively of the calcitic
polymorph, which is said to be trigonal-rhombohedral and represents
the most stable form of the calcium carbonate polymorphs. The term
"source" of the calcium carbonate in the meaning of the present
application refers to the naturally occurring mineral material from
which the calcium carbonate is obtained. The source of the calcium
carbonate may comprise further naturally occurring components such
as magnesium carbonate, alumino silicate etc.
[0073] In general, the grinding of natural ground calcium carbonate
may be a dry or wet grinding step and may be carried out with any
conventional grinding device, for example, under conditions such
that comminution predominantly results from impacts with a
secondary body, i.e. in one or more of: a ball mill, a rod mill, a
vibrating mill, a roll crusher, a centrifugal impact mill, a
vertical bead mill, an attrition mill, a pin mill, a hammer mill, a
pulveriser, a shredder, a de-clumper, a knife cutter, or other such
equipment known to the skilled man. In case the calcium carbonate
containing mineral material comprises a wet ground calcium
carbonate containing mineral material, the grinding step may be
performed under conditions such that autogenous grinding takes
place and/or by horizontal ball milling, and/or other such
processes known to the skilled man. The wet processed ground
calcium carbonate containing mineral material thus obtained may be
washed and dewatered by well-known processes, e.g. by flocculation,
filtration or forced evaporation prior to drying. The subsequent
step of drying (if necessary) may be carried out in a single step
such as spray drying, or in at least two steps. It is also common
that such a mineral material undergoes a beneficiation step (such
as a flotation, bleaching or magnetic separation step) to remove
impurities.
[0074] According to one embodiment of the present invention the
source of natural ground calcium carbonate (GCC) is selected from
marble, chalk, limestone, or mixtures thereof. Preferably, the
source of ground calcium carbonate is marble, and more preferably
dolomitic marble and/or magnesitic marble. According to one
embodiment of the present invention the GCC is obtained by dry
grinding. According to another embodiment of the present invention
the GCC is obtained by wet grinding and subsequent drying.
[0075] According to one embodiment of the present invention, the
calcium carbonate comprises one type of natural ground calcium
carbonate. According to another embodiment of the present
invention, the calcium carbonate comprises a mixture of two or more
types of natural ground calcium carbonates selected from different
sources.
[0076] "Precipitated calcium carbonate" (PCC) in the meaning of the
present invention is a synthesized material, generally obtained by
precipitation following reaction of carbon dioxide and calcium
hydroxide in an aqueous environment or by precipitation of calcium
and carbonate ions, for example CaCl.sub.2) and Na.sub.2CO.sub.3,
out of solution. Further possible ways of producing PCC are the
lime soda process, or the Solvay process in which PCC is a
by-product of ammonia production. Precipitated calcium carbonate
exists in three primary crystalline forms: calcite, aragonite and
vaterite, and there are many different polymorphs (crystal habits)
for each of these crystalline forms. Calcite has a trigonal
structure with typical crystal habits such as scalenohedral
(S-PCC), rhombohedral (R-PCC), hexagonal prismatic, pinacoidal,
colloidal (C-PCC), cubic, and prismatic (P-PCC). Aragonite is an
orthorhombic structure with typical crystal habits of twinned
hexagonal prismatic crystals, as well as a diverse assortment of
thin elongated prismatic, curved bladed, steep pyramidal, chisel
shaped crystals, branching tree, and coral or worm-like form.
Vaterite belongs to the hexagonal crystal system. The obtained PCC
slurry can be mechanically dewatered and dried.
[0077] According to one embodiment of the present invention, the
precipitated calcium carbonate is precipitated calcium carbonate,
preferably comprising aragonitic, vateritic or calcitic
mineralogical crystal forms or mixtures thereof.
[0078] Precipitated calcium carbonate may be ground prior to the
treatment with carbon dioxide and at least one H.sub.3O.sup.+ ion
donor by the same means as used for grinding natural ground calcium
carbonate as described above.
[0079] "Dolomite" in the meaning of the present invention is a
calcium carbonate containing mineral, namely a carbonic
calcium-magnesium-mineral, having the chemical composition of
CaMg(CO.sub.3).sub.2 ("CaCO.sub.3.MgCO.sub.3"). A dolomite mineral
may contain at least 30.0 wt.-% MgCO.sub.3, based on the total
weight of dolomite, preferably more than 35.0 wt.-%, and more
preferably more than 40.0 wt.-% MgCO.sub.3.
[0080] According to one embodiment of the present invention, the
calcium carbonate-comprising material is in form of particles
having a weight median particle size d.sub.50 of 0.05 to 10.0
.mu.m, preferably 0.2 to 5.0 .mu.m, more preferably 0.4 to 3.0
.mu.m, and most preferably 0.6 to 1.2 .mu.m.
[0081] According to a further embodiment of the present invention,
the calcium carbonate-comprising material is in form of particles
having a top cut particle size d.sub.98 of 0.15 to 55 .mu.m,
preferably 1 to 40 .mu.m, more preferably 2 to 25 .mu.m, and most
preferably 3 to 15 .mu.m.
[0082] The calcium carbonate-comprising material may have a
specific surface area (BET) from 1 to 200 m.sup.2/g, as measured
using nitrogen and the BET method according to ISO 9277. According
to one embodiment the specific surface area (BET) of the calcium
carbonate-comprising material is from 1 to 150 m.sup.2/g,
preferably from 2 to 60 m.sup.2/g, and more preferably from 2 to 15
m.sup.2/g, as measured using nitrogen and the BET method according
to ISO 9277.
[0083] The calcium carbonate-comprising material may be used dry or
in form of an aqueous suspension. According to a preferred
embodiment, the calcium carbonate-comprising material is in form of
an aqueous suspension having a solids content within the range of 1
wt.-% to 90 wt.-%, preferably 3 wt.-% to 60 wt.-%, more preferably
5 wt.-% to 40 wt.-%, and most preferably 10 wt.-% to 25 wt.-%,
based on the weight of the aqueous suspension.
[0084] The term "aqueous" suspension refers to a system, wherein
the liquid phase comprises, preferably consists of, water. However,
said term does not exclude that the liquid phase of the aqueous
suspension comprises minor amounts of at least one water-miscible
organic solvent selected from the group comprising methanol,
ethanol, acetone, acetonitrile, tetrahydrofuran and mixtures
thereof. If the aqueous suspension comprises at least one
water-miscible organic solvent, the liquid phase of the aqueous
suspension comprises the at least one water-miscible organic
solvent in an amount of from 0.1 to 40.0 wt.-% preferably from 0.1
to 30.0 wt.-%, more preferably from 0.1 to 20.0 wt.-% and most
preferably from 0.1 to 10.0 wt.-%, based on the total weight of the
liquid phase of the aqueous suspension. For example, the liquid
phase of the aqueous suspension consists of water.
[0085] According to a preferred embodiment of the present
invention, the aqueous suspension consists of water and the calcium
carbonate-comprising material.
[0086] Alternatively, the aqueous suspension of the calcium
carbonate-comprising material may comprise further additives, for
example, a dispersant. A suitable dispersant may be selected from
polyphosphates, and is in particular a tripolyphosphate. Another
suitable dispersant may be selected from the group comprising
homopolymers or copolymers of polycarboxylic acid salts based on,
for example, acrylic acid, methacrylic acid, maleic acid, fumaric
acid or itaconic acid and acrylamide or mixtures thereof.
Homopolymers or copolymers of acrylic acid are especially
preferred. The weight average molecular weight M.sub.w of such
products is preferably in the range from 2 000 to 15 000 g/mol,
with a weight average molecular weight M.sub.w from 3 000 to 7 000
g/mol or 3 500 to 6 000 g/mol being especially preferred. According
to an exemplary embodiment, the dispersant is sodium polyacrylate
having a weight average molecular weight M.sub.w from 2 000 to 15
000 g/mol, preferably from 3 000 to 7 000 g/mol, and most
preferably from 3 500 to 6 000 g/mol.
[0087] According to one embodiment of the present invention, the
calcium carbonate-comprising material provided in process step a)
is natural ground calcium carbonate and/or precipitated calcium
carbonate, preferably an aqueous suspension of natural ground
calcium carbonate and/or precipitated calcium carbonate having a
solids content within the range of 1 wt.-% to 90 wt.-%, preferably
3 wt.-% to 60 wt.-%, more preferably 5 wt.-% to 40 wt.-%, and most
preferably 10 wt.-% to 25 wt.-%, based on the weight of the aqueous
suspension
Process Step b)
[0088] According to step b) of the process of the present
invention, at least one H.sub.3O.sup.+ ion donor is provided. An
"H.sub.3O.sup.+ ion donor" in the context of the present invention
is a Bronsted acid and/or an acid salt, i.e. a salt containing an
acidic hydrogen.
[0089] The at least one H.sub.3O.sup.+ ion donor may be any strong
acid, medium-strong acid, or weak acid, or a mixture thereof,
generating H.sub.3O.sup.+ ions under the preparation conditions.
According to the present invention, the at least one H.sub.3O.sup.+
ion donor can also be an acid salt, generating H.sub.3O.sup.+ ions
under the preparation conditions.
[0090] According to one embodiment, the at least one H.sub.3O.sup.+
ion donor is a strong acid having a pK.sub.a of 0 or less at
20.degree. C. According to another embodiment, the at least one
H.sub.3O.sup.+ ion donor is a medium-strong acid having a pK.sub.a
value from 0 to 2.5 at 20.degree. C.
[0091] If the pK.sub.a at 20.degree. C. is 0 or less, the acid is
preferably selected from sulphuric acid, hydrochloric acid, or
mixtures thereof. If the pK.sub.a at 20.degree. C. is from 0 to
2.5, the H.sub.3O.sup.+ ion donor is preferably selected from
H.sub.2SO.sub.3, H.sub.3PO.sub.4, oxalic acid, or mixtures thereof.
The at least one H.sub.3O.sup.+ ion donor can also be an acid salt,
for example, HSO.sub.4.sup.- or H.sub.2PO.sub.4.sup.-, being at
least partially neutralized by a corresponding cation such as
Li.sup.+, Na.sup.+ or K.sup.+, or HPO.sub.4.sup.2-, being at least
partially neutralised by a corresponding cation such as Li.sup.+,
Na.sup.+, K.sup.+, K.sup.+, Mg.sup.2+ or Ca.sup.2+. The at least
one H.sub.3O.sup.+ ion donor can also be a mixture of one or more
acids and one or more acid salts.
[0092] According to still another embodiment, the at least one
H.sub.3O.sup.+ ion donor is a weak acid having a pK.sub.a value of
greater than 2.5 and less than or equal to 7, when measured at
20.degree. C., associated with the ionisation of the first
available hydrogen, and having a corresponding anion, which is
capable of forming water-soluble calcium salts. Subsequently, at
least one water-soluble salt, which in the case of a
hydrogen-containing salt has a pK.sub.a of greater than 7, when
measured at 20.degree. C., associated with the ionisation of the
first available hydrogen, and the salt anion of which is capable of
forming water-insoluble calcium salts, is additionally provided.
According to the preferred embodiment, the weak acid has a pK.sub.a
value from greater than 2.5 to 5 at 20.degree. C., and more
preferably the weak acid is selected from the group consisting of
acetic acid, formic acid, propanoic acid, and mixtures thereof.
Exemplary cations of said water-soluble salt are selected from the
group consisting of potassium, sodium, lithium and mixtures
thereof. In a more preferred embodiment, said cation is sodium or
potassium. Exemplary anions of said water-soluble salt are selected
from the group consisting of phosphate, dihydrogen phosphate,
monohydrogen phosphate, oxalate, silicate, mixtures thereof and
hydrates thereof. In a more preferred embodiment, said anion is
selected from the group consisting of phosphate, dihydrogen
phosphate, monohydrogen phosphate, mixtures thereof and hydrates
thereof. In a most preferred embodiment, said anion is selected
from the group consisting of dihydrogen phosphate, monohydrogen
phosphate, mixtures thereof and hydrates thereof. Water-soluble
salt addition may be performed dropwise or in one step. In the case
of drop wise addition, this addition preferably takes place within
a time period of 10 minutes. It is more preferred to add said salt
in one step.
[0093] According to one embodiment of the present invention, the at
least one H.sub.3O.sup.+ ion donor is selected from the group
consisting of hydrochloric acid, sulphuric acid, sulphurous acid,
phosphoric acid, citric acid, oxalic acid, an acidic salt, acetic
acid, formic acid, and mixtures thereof. Preferably the at least
one H.sub.3O.sup.+ ion donor is selected from the group consisting
of hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric
acid, oxalic acid, H.sub.2PO.sub.4.sup.-, being at least partially
neutralised by a cation selected from Li.sup.+, Na.sup.+ and/or
K.sup.+, HPO.sub.4.sup.2-, being at least partially neutralised by
a cation selected from Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.2+,
and/or Ca.sup.2+, and mixtures thereof, more preferably the at
least one H.sub.3O.sup.+ ion donor is selected from the group
consisting of hydrochloric acid, sulphuric acid, sulphurous acid,
phosphoric acid, oxalic acid, or mixtures thereof, and most
preferably, the at least one H.sub.3O.sup.+ ion donor is phosphoric
acid.
[0094] The at least one H.sub.3O.sup.+ ion donor can be provided in
solid form or in form of a solution. According to a preferred
embodiment, the at least one H.sub.3O.sup.+ ion donor is provided
in form of a solution.
[0095] According to one embodiment the at least one H.sub.3O.sup.+
ion donor is provided in form of an aqueous solution comprising the
at least one H.sub.3O.sup.+ ion donor in an amount from 0.1 to 100
wt.-%, based on the total weight of the aqueous solution,
preferably in an amount from 1 to 80 wt.-%, more preferably in an
amount from 10 to 50 wt.-%, and most preferably in an amount from
20 to 40 wt.-%.
[0096] According to one embodiment, the molar ratio of the at least
one H.sub.3O.sup.+ ion donor to the calcium carbonate-comprising
material is from 0.01 to 4, preferably from 0.02 to 2, more
preferably from 0.05 to 1, and most preferably from 0.1 to
0.58.
[0097] According to another embodiment, the at least one
H.sub.3O.sup.+ ion donor is provided in an amount from 1 to 40
wt.-%, based on the total weight of the calcium
carbonate-comprising material, preferably from 5 to 30 wt.-%, more
preferably from 10 to 20 wt.-%, and most preferably from 15 to 18
wt.-%.
Process Step c)
[0098] According to step c) of the process of the present invention
at least one water-soluble metal cation source is provided.
[0099] According to one embodiment the at least one water-soluble
metal cation source is selected from the group consisting of a
water-soluble metal salt, a water-soluble transition metal complex,
a water-soluble metal hydroxide, a water-soluble metal oxide, and
mixtures thereof.
[0100] The water-soluble metal cation source may be selected from
the group consisting of a water-soluble transition metal salt, a
water-soluble group(III) metal salt, and mixtures thereof.
According to one embodiment the water-soluble metal cation source
is selected from the group consisting of water-soluble salts of
aluminium, chromium, manganese, iron, cobalt, nickel, copper, zinc,
silver, gold, zirconium, palladium, platinum, and mixtures
thereof.
[0101] Examples of a suitable water-soluble aluminium salts are
aluminium chloride (AlCl.sub.3) or aluminium sulphate
(Al.sub.2(SO.sub.4).sub.3). The water-soluble aluminium salt may be
an anhydrous salt or a hydrate salt.
[0102] Examples of a suitable water-soluble chromium salt are
chromium bromide (CrBr.sub.3), chromium chloride (CrCl.sub.2),
chromium fluoride (CrF.sub.2), chromium nitrate
(Cr(NO.sub.3).sub.3), or chromium perchlorate
(Cr(ClO.sub.4).sub.3). The water-soluble chromium salt may be an
anhydrous salt or a hydrate salt.
[0103] Examples of a suitable water-soluble manganese salt are
manganese bromide (MnBr.sub.2), manganese chloride (MnCl.sub.2),
manganese nitrate (Mn(NO.sub.3).sub.2), manganese sulphate
(MnSO.sub.4), manganese carbonate (MnCO.sub.3), manganese(II)
acetate, manganese(II) benzoate, manganese(II) formate,
manganese(II) tartrate, or manganese(II) phosphate. The
water-soluble manganese salt may be an anhydrous salt or a hydrate
salt.
[0104] Examples of a suitable water-soluble iron salt are iron
bromide (FeBr.sub.2), iron chloride (FeCl.sub.2, FeCl.sub.3), iron
iodide (FeI.sub.2), iron nitrate (Fe(NO.sub.3).sub.3), potassium
hexacyanoferrate (K.sub.4Fe(CN).sub.6), ammonium iron sulphate
(NH.sub.4).sub.2Fe(SO.sub.4).sub.2, or iron sulphate (FeSO.sub.4).
The water-soluble iron salt may be an anhydrous salt or a hydrate
salt.
[0105] Examples of a suitable water-soluble cobalt salt are cobalt
bromide (CuBr.sub.2), cobalt chloride (CoCl.sub.2), cobalt chlorate
(Co(ClO.sub.3).sub.2), cobalt iodide (CoI.sub.2), cobalt nitrate
(Co(NO.sub.3).sub.2), or cobalt sulphate (CoSO.sub.4). The
water-soluble cobalt salt may be an anhydrous salt or a hydrate
salt.
[0106] Examples of a suitable water-soluble copper salt are copper
bromide (CuBr.sub.2), copper chloride (CuCl.sub.2), copper nitrate
(Cu(NO.sub.3).sub.2), copper acetate (C.sub.4H.sub.6CuO.sub.4),
copper sulphate (CuSO.sub.4), or copper iodide (CuI.sub.2). The
water-soluble copper salt may be an anhydrous salt or a hydrate
salt.
[0107] Examples of a suitable water-soluble zinc salt are zinc
bromide (ZnBr.sub.2), zinc chloride (ZnCl.sub.2), zinc nitrate
(Zn(NO.sub.3).sub.2), zinc iodide (ZnI.sub.2), zinc sulphate,
zinc(II) acetate, or zinc(II) citrate. The water-soluble zinc salt
may be an anhydrous salt or a hydrate salt.
[0108] Examples of suitable water-soluble silver salts are silver
perchlorate (AgClO.sub.4) and silver nitrate (AgNO.sub.3). The
water-soluble silver salt may be an anhydrous salt or a hydrate
salt.
[0109] Examples of a suitable water-soluble gold salts are
gold(III) bromide, gold(III) chloride, or potassium
dicyanoaurate(I) (K[Au(CN).sub.2]). The water-soluble gold salt may
be an anhydrous salt or a hydrate salt.
[0110] An example of a suitable water-soluble zirconium salt is
zirconium(IV) sulphate. The water-soluble zirconium salt may be an
anhydrous salt or a hydrate salt.
[0111] Examples of suitable water-soluble palladium salts are
palladium(II) sulphate, palladium(II) nitrate, tetraammine
palladium hydrogen carbonate, or diamine dichloro palladium(II).
The water-soluble palladium salt may be an anhydrous salt or a
hydrate salt.
[0112] Examples of a suitable water-soluble platinum salts are
platinum(IV) bromide, platinum(IV) chloride, Na.sub.2PtCl.sub.6, or
H.sub.2PtCl.sub.6. The water-soluble platinum salt may be an
anhydrous salt or a hydrate salt.
[0113] As used herein, a "hydrate" is an inorganic salt containing
water molecules combined in a definite ratio as an integral part of
the crystal. Depending on the number of water molecules per formula
unit of salt, the hydrate may be designated as monohydrate,
dihydrate, trihydrate, tetrahydrate, pentahydrate, hexahydrate,
heptahydrate, octahydrate, nonahydrate, decahydrate, hemihydrates,
etc.
[0114] Examples of water-soluble transition metal complexes are
Na.sub.2PdCl.sub.4, Na.sub.2PtCl.sub.4, Pd(OAc).sub.2,
Pd(H.sub.2NCH.sub.2CH.sub.2NH.sub.2)Cl.sub.2, PdCl.sub.2.
[0115] Water-soluble metal hydroxides or water-soluble metal oxides
may also be a suitable metal cation source.
[0116] According to a preferred embodiment the water-soluble metal
cation source is a water-soluble salt of copper and/or zinc, and
more preferably the water-soluble metal cation source is selected
from the group consisting of copper nitrate, copper sulphate,
copper acetate, copper chloride, copper bromide, copper iodide,
zinc nitrate, zinc sulphate, zinc acetate, zinc chloride, zinc
bromide, zinc iodide, hydrates thereof, and mixtures thereof.
[0117] According to one embodiment the at least one water-soluble
metal cation source is provided in an amount from 0.01 to 60 wt.-%,
based on the total weight of the calcium carbonate-comprising
material, preferably from 0.05 to 50 wt.-%, more preferably from
0.1 to 25 wt.-%, and most preferably from 0.5 to 10 wt.-%.
According to an exemplary embodiment, the at least one
water-soluble metal cation source is provided in an amount from 1
to 10 wt.-%, based on the total weight of the calcium
carbonate-comprising material, preferably from 2 to 8 wt.-%, more
preferably from 3 to 6 wt.-%, and most preferably from 4 to 5
wt.-%.
[0118] The at least one water soluble metal salt, water soluble
metal hydroxide, water soluble metal oxide or mixtures thereof can
be provided in form of a solution, a suspension or as a dry
material.
[0119] According to one embodiment the at least one water soluble
metal salt, water soluble metal hydroxide, water soluble metal
oxide or mixtures thereof is provided as dry material. The dry
material may be in the form of powder, flakes, granules etc. and
most preferably is in the form of a powder.
[0120] According to another embodiment the at least one
water-soluble metal cation source is provided in form of an aqueous
solution or aqueous suspension, preferably an aqueous solution,
comprising the at least one water-soluble metal cation source in an
amount from 0.01 to 10 wt-%, based on the total weight of the
aqueous solution, preferably in an amount from 0.1 to 8 wt.-%, more
preferably in an amount from 0.4 to 5 wt.-%, and most preferably in
an amount from 0.8 to 2 wt.-%.
Process Step d)
[0121] According to step d) of the process of the present
invention, the calcium carbonate-comprising material of step a) is
treated with the at least one H.sub.3O.sup.+ ion donor of step b)
and carbon dioxide in an aqueous medium to form a suspension of
surface-reacted calcium carbonate, wherein the carbon dioxide is
formed in-situ by the H.sub.3O.sup.+ ion donor treatment and/or is
supplied from an external source, and wherein the at least one
water-soluble metal cation source of step c) is added during step
d).
[0122] The calcium carbonate-comprising material can be treated
with the at least one H.sub.3O.sup.+ ion donor by providing an
aqueous suspension of the calcium carbonate-comprising material and
adding the at least one H.sub.3O.sup.+ ion donor to said
suspension. The at least one H.sub.3O.sup.+ ion donor can be added
to the suspension as a concentrated solution or a more diluted
solution. As an alternative, it is also possible to treat the
calcium carbonate-comprising material with the at least one
H.sub.3O.sup.+ ion donor by adding the calcium carbonate-comprising
material to a solution of the at least one H.sub.3O.sup.+ ion
donor.
[0123] The least one H.sub.3O.sup.+ ion donor of step b) and the at
least one water-soluble metal cation source of step c) may be
provided in form of separate solutions and/or in form of combined
solutions.
[0124] According to one embodiment, in step d) the calcium
carbonate-comprising material is treated with a solution comprising
the at least one H.sub.3O.sup.+ ion donor of step b) and the at
least one water-soluble metal cation source of step c).
[0125] According to another embodiment, in step d) the calcium
carbonate-comprising material is treated with a first solution
comprising a first part of the at least one H.sub.3O.sup.+ ion
donor of step b), and subsequently, with a second solution
comprising the remaining part of the at least one H.sub.3O.sup.+
ion donor of step b) and the at least one water-soluble metal
cation source of step c). The first solution may comprise less than
or equal to 50 wt.-% of the at least one H.sub.3O.sup.+ ion donor,
based on the total amount of the at least one H.sub.3O.sup.+ ion
donor, preferably less than or equal to 40 wt.-%, more preferably
less than or equal to 30 wt.-%, and most preferably less than or
equal to 20 wt.-%. For example, the first solution may comprise
from 0.1 to 50 wt.-% of the at least one H.sub.3O.sup.+ ion donor,
based on the total amount of the at least one H.sub.3O.sup.+ ion
donor, preferably from 1 to 40 wt.-%, more preferably from 5 to 30
wt.-%, and most preferably from 10 to 20 wt.-%.
[0126] According to still another embodiment, in step b) a first
H.sub.3O.sup.+ ion donor and a second H.sub.3O.sup.+ ion donor are
provided, and in step d) the calcium carbonate-comprising material
is treated with a first solution comprising the first
H.sub.3O.sup.+ ion donor, and subsequently, with a second solution
comprising the second H.sub.3O.sup.+ ion donor and the at least one
water-soluble metal cation source of step c).
[0127] According to one embodiment in step d) the calcium
carbonate-comprising material is treated with a first solution
comprising a first part of the at least one H.sub.3O ion donor of
step b), and subsequently, with a second solution comprising the
remaining part of the at least one H.sub.3O.sup.+ ion donor of step
b) and the at least one water-soluble metal cation source of step
c), wherein the first solution comprises less than 50 wt.-% of the
at least one H.sub.3O.sup.+ ion donor, based on the total amount of
the at least one H.sub.3O.sup.+ ion donor, preferably less than 40
wt.-%, more preferably less than 30 wt.-%, and most preferably less
than 20 wt.-%.
[0128] According to a preferred embodiment in step d) the calcium
carbonate-comprising material is treated with a solution comprising
the at least one H.sub.3O.sup.+ ion donor in an amount from 1 to 80
wt.-%, preferably in an amount from 2 to 50 wt.-%, more preferably
in an amount from 5 to 30 wt.-%, and most preferably in an amount
from 10 to 20 wt.-%, based on the total weight of the aqueous
solution, and the at least one water-soluble metal cation source in
an amount from 0.01 to 10 wt.-%, preferably in an amount from 0.1
to 8 wt.-%, more preferably in an amount from 0.4 to 5 wt.-%, and
most preferably in an amount from 0.8 to 2 wt.-%, based on the
total weight of the aqueous solution.
[0129] According to a preferred embodiment, the calcium
carbonate-comprising material is a natural ground calcium
carbonate, the at least one H.sub.3O.sup.+ ion donor is phosphoric
acid, the at least one water-soluble metal cation source is
selected from the group consisting of copper nitrate, copper
sulphate, copper acetate, copper chloride, copper bromide, copper
iodide, zinc nitrate, zinc sulphate, zinc acetate, zinc chloride,
zinc bromide, zinc iodide, hydrates thereof, and mixtures thereof,
and in step d) the calcium carbonate-comprising material is treated
with a solution comprising the at least one H.sub.3O.sup.+ ion
donor of step b) and the at least one water-soluble metal cation
source of step c).
[0130] According to a preferred embodiment, the calcium
carbonate-comprising material is a natural ground calcium
carbonate, the at least one H.sub.3O.sup.+ ion donor is phosphoric
acid, the at least one water-soluble metal cation source is
selected from the group consisting of copper nitrate, copper
sulphate, copper acetate, copper chloride, copper bromide, copper
iodide, zinc nitrate, zinc sulphate, zinc acetate, zinc chloride,
zinc bromide, zinc iodide, hydrates thereof, and mixtures thereof,
and in step d) the calcium carbonate-comprising material is treated
with a first solution comprising a first part of the at least one
H.sub.3O.sup.+ ion donor of step b), and subsequently, with a
second solution comprising the remaining part of the at least one
H.sub.3O.sup.+ ion donor of step b) and the at least one
water-soluble metal cation source of step c).
[0131] According to one embodiment, the at least one H.sub.3O.sup.+
ion donor is added over a time period of at least 1 min, preferably
at least 5 min, and more preferably at least 10 min. In case the
calcium carbonate-comprising material is treated with a first and a
second solution, the first solution comprising a first part of the
at least one H.sub.3O.sup.+ ion donor or a first H.sub.3O.sup.+ ion
donor may be added over a time period of at least 1 min, preferably
at least 5 min, and more preferably at least 10 min, and the second
solution comprising the remaining part of the at least one
H.sub.3O.sup.+ ion donor or the second H.sub.3O.sup.+ ion donor and
the at least one water-soluble metal cation source may be added
over a time period of at least 1 min, preferably at least 5 min,
and more preferably at least 10 min.
[0132] According to step d) of the process of the present
invention, the calcium carbonate-comprising material is treated
with carbon dioxide. If a strong acid such as sulphuric acid or
hydrochloric acid is used for the H.sub.3O.sup.+ ion donor
treatment of the calcium carbonate-comprising material, the carbon
dioxide is automatically formed. Alternatively or additionally, the
carbon dioxide can be supplied from an external source.
[0133] H.sub.3O.sup.+ ion donor treatment and treatment with carbon
dioxide can be carried out simultaneously which is the case when a
strong or medium-strong acid is used. It is also possible to carry
out H.sub.3O.sup.+ ion donor treatment first, e.g. with a medium
strong acid having a pK.sub.a in the range of 0 to 2.5 at
20.degree. C., wherein carbon dioxide is formed in situ, and thus,
the carbon dioxide treatment will automatically be carried out
simultaneously with the H.sub.3O.sup.+ ion donor treatment,
followed by the additional treatment with carbon dioxide supplied
from an external source.
[0134] Preferably, the concentration of gaseous carbon dioxide in
the suspension formed in step d) is, in terms of volume, such that
the ratio (volume of suspension):(volume of gaseous CO.sub.2) is
from 1:0.05 to 1:20, even more preferably 1:0.05 to 1:5.
[0135] In a preferred embodiment, the H.sub.3O.sup.+ ion donor
treatment step and/or the carbon dioxide treatment of step d) are
repeated at least once, more preferably several times.
[0136] Subsequent to the H.sub.3O ion donor treatment and carbon
dioxide treatment, the pH of the aqueous suspension, measured at
20.degree. C., naturally reaches a value of greater than 6.0,
preferably greater than 6.5, more preferably greater than 7.0, even
more preferably greater than 7.5, thereby preparing the
surface-reacted natural or precipitated calcium carbonate as an
aqueous suspension having a pH of greater than 6.0, preferably
greater than 6.5, more preferably greater than 7.0, even more
preferably greater than 7.5.
[0137] According to one embodiment of the present invention, step
d) is carried out at a temperature from 20 to 90.degree. C.,
preferably from 30 to 85.degree. C., more preferably from 40 to
80.degree. C., even more preferably from 50 to 75.degree. C., and
most preferably from 60 to 70.degree. C.
[0138] According to one embodiment, the process step d) is carried
out for at least 1 min, preferably for at least 5 min, more
preferably for at least 10 min, and most preferably for at least 15
min.
[0139] Process step d) may be carried out by simply adding, for
example, by pouring, discharging, or injecting, the at least one
H.sub.3O.sup.+ ion donor and/or the at least one water-soluble
metal cation source into the calcium carbonate-comprising material.
According to one embodiment, process step d) is carried out under
mixing conditions. Suitable mixing methods are known to the skilled
person. Examples of suitable mixing methods are shaking, mixing,
stirring, agitating, ultrasonication, or inducing a turbulent or
laminar flow by means such as baffles or lamellae. Suitable mixing
equipment is known to the skilled person, and may be selected, for
example, from stirrers, such as rotor stator systems, blade
stirrers, propeller stirrers, turbine stirrers, or anchor stirrers,
static mixers such as pipes including baffles or lamellae.
According to an exemplary embodiment of the present invention, a
rotor stator stirrer system is used.
[0140] According to another exemplary embodiment, in step d) the
formed suspension is mixed so as to develop an essentially laminar
flow. The skilled person will adapt the mixing conditions such as
the mixing speed and temperature according to his process
equipment.
[0141] Depending on the amount of water that is introduced during
step d) by contacting the aforementioned compounds, additional
water may be introduced during process step d), for example, in
order to control and/or maintain and/or achieve the desired solids
content or Brookfield viscosity of the obtained aqueous suspension.
According to one embodiment the solids content of the mixture
obtained in step d) is from 5 to 80 wt.-%, preferably from 20 to 78
wt.-%, based on the total weight of the mixture. The Brookfield
viscosity of the obtained aqueous suspension may be from 10 to 10
000 mPas, preferably from 50 to 1 000 mPas. The process of the
present invention may be carried out in form of a continuous
process or a batch process, preferably in from of a continuous
process.
Additional Process Steps
[0142] According to one embodiment, the process of the present
invention further comprises a step of agitating the aqueous
suspension after step d). Preferably, the suspension is agitated
for at least 1 min, preferably for at least 5 min, more preferably
for at least 10 min, and most preferably for at least 15 min.
[0143] The aqueous suspension of surface-reacted calcium carbonate
may be further processed, e.g., the surface-reacted calcium
carbonate may be separated from the aqueous suspension and/or
subjected to a drying step.
[0144] According to one embodiment, the process of the present
invention further comprises a step c) of separating the
surface-reacted calcium carbonate from the aqueous suspension
obtained in step d). Thus, a process for manufacturing a
surface-reacted calcium carbonate may comprise the following steps:
[0145] a) providing a calcium carbonate-comprising material, [0146]
b) providing at least one H.sub.3O.sup.+ ion donor, [0147] c)
providing at least one water-soluble metal cation source, and
[0148] d) treating the calcium carbonate-comprising material of
step a) with the at least one H.sub.3O.sup.+ ion donor of step b)
and carbon dioxide in an aqueous medium to form an aqueous
suspension of surface-reacted calcium carbonate, [0149] wherein the
carbon dioxide is formed in-situ by the H.sub.3O.sup.+ ion donor
treatment and/or is supplied from an external source, and [0150]
wherein the at least one water-soluble metal cation source of step
c) is added during step d), and [0151] c) separating the
surface-reacted calcium carbonate from the aqueous suspension
obtained from step d).
[0152] The surface-reacted calcium carbonate obtained from step d)
may be separated from the aqueous suspension by any conventional
means of separation known to the skilled person. According to one
embodiment of the present invention, in process step e) the
surface-reacted calcium carbonate is separated mechanically and/or
thermally. Examples of mechanical separation processes are
filtration, e.g. by means of a drum filter or filter press,
nanofiltration, or centrifugation. An example for a thermal
separation process is a concentrating process by the application of
heat, for example, in an evaporator. According to a preferred
embodiment, in process step e) the surface-reacted calcium
carbonate is separated mechanically, preferably by filtration
and/or centrifugation.
[0153] After separation, the surface-reacted calcium carbonate can
be dried in order to obtain a dried surface-reacted calcium
carbonate. According to one embodiment, the process of the present
invention further comprises a step f) of drying the surface-reacted
calcium carbonate after step d) or after step e), if present, at a
temperature in the range from 60 to 600.degree. C., preferably
until the moisture content of the surface-reacted calcium carbonate
is between 0.01 and 5 wt.-%, based on the total weight of the dried
surface-reacted calcium carbonate.
[0154] According to one embodiment of the present invention, a
process for manufacturing a dried surface-reacted calcium carbonate
is provided comprising the following steps: [0155] a) providing a
calcium carbonate-comprising material, [0156] b) providing at least
one H.sub.3O.sup.+ ion donor, [0157] c) providing at least one
water-soluble metal cation source, and [0158] d) treating the
calcium carbonate-comprising material of step a) with the at least
one H.sub.3O.sup.+ ion donor of step b) and carbon dioxide in an
aqueous medium to form an aqueous suspension of surface-reacted
calcium carbonate, [0159] wherein the carbon dioxide is formed
in-situ by the H.sub.3O.sup.+ ion donor treatment and/or is
supplied from an external source, and [0160] wherein the at least
one water-soluble metal cation source of step c) is added during
step d), [0161] e) separating the surface-reacted calcium carbonate
from the aqueous suspension obtained from step d), and [0162] f)
drying the surface-reacted calcium carbonate.
[0163] In general, the drying step f) may take place using any
suitable drying equipment and can, for example, include thermal
drying and/or drying at reduced pressure using equipment such as an
evaporator, a flash drier, an oven, a spray drier and/or drying in
a vacuum chamber. The drying step f) can be carried out at reduced
pressure, ambient pressure or under increased pressure. For
temperatures below 100.degree. C. it may be preferred to carry out
the drying step under reduced pressure.
[0164] According to one preferred embodiment, the separation is
carried out by a thermal method. This may allow to dry the
surface-reacted calcium carbonate subsequently without changing the
equipment.
[0165] According to one embodiment, in process step f) the
surface-reacted calcium carbonate is dried until the moisture
content of the formed surface-reacted calcium carbonate is less
than or equal to 1.0 wt.-%, based on the total weight of the dried
surface-reacted calcium carbonate, preferably less than or equal to
0.5 wt.-%, and more preferably less than or equal to 0.2 wt.-%.
According to another embodiment, in process step d) the
surface-reacted calcium carbonate is dried until the moisture
content of the formed surface-reacted calcium carbonate is between
0.01 and 0.15 wt.-%, preferably between 0.02 and 0.10 wt.-%, and
more preferably between 0.03 and 0.07 wt.-%, based on the total
weight of the dried surface-reacted calcium carbonate.
The Surface-Reacted Calcium Carbonate
[0166] According to a further aspect of the present invention, a
surface-reacted calcium carbonate is provided, wherein the
surface-reacted calcium carbonate is obtainable by a process of the
present invention. Thus, the surface-reacted calcium carbonate may
be obtained by a process comprising the steps of: [0167] a)
providing a calcium carbonate-comprising material, [0168] b)
providing at least one H.sub.3O.sup.+ ion donor, [0169] c)
providing at least one water-soluble metal cation source, and
[0170] d) treating the calcium carbonate-comprising material of
step a) with the at least one H.sub.3O.sup.+ ion donor of step b)
and carbon dioxide in an aqueous medium to form an aqueous
suspension of surface-reacted calcium carbonate, wherein the carbon
dioxide is formed in-situ by the H.sub.3O.sup.+ ion donor treatment
and/or is supplied from an external source, and [0171] wherein the
at least one water-soluble metal cation source of step c) is added
during step d).
[0172] The surface-reacted calcium carbonate may have different
particle shapes, such as e.g. the shape of roses, golf balls and/or
brains.
[0173] According to one embodiment the surface-reacted calcium
carbonate has a specific surface area of from 15 m.sup.2/g to 200
m.sup.2/g, preferably from 20 m.sup.2/g to 180 m.sup.2/g, more
preferably from 25 m.sup.2/g to 160 m.sup.2/g, even more preferably
from 27 m.sup.2/g to 150 m.sup.2/g, most preferably from 30
m.sup.2/g to 140 m.sup.2/g, measured using nitrogen and the BET
method. For example, the surface-reacted calcium carbonate may have
a specific surface area of from 27 m.sup.2/g to 100 m.sup.2/g,
measured using nitrogen and the BET method. The BET specific
surface area in the meaning of the present invention is defined as
the surface area of the particles divided by the mass of the
particles. As used therein the specific surface area is measured by
adsorption using the BET isotherm (ISO 9277:1995) and is specified
in m.sup.2/g.
[0174] According to one embodiment, the surface-reacted calcium
carbonate has a volume determined median particle size
d.sub.50(vol) from 1 to 75 .mu.m, preferably from 2 to 50 .mu.m,
more preferably from 3 to 40 .mu.m, even more preferably from 4 to
30 .mu.m, and most preferably from 5 to 15 .mu.m, and/or a volume
determined top cut particle size d.sub.98(vol) from 2 to 150 .mu.m,
preferably from 4 to 100 .mu.m, more preferably from 6 to 80 .mu.m,
even more preferably from 8 to 60 .mu.m, and most preferably from
10 to 30 .mu.m.
[0175] The surface-reacted calcium carbonate may have an
intra-particle intruded specific pore volume in the range from 0.1
to 2.3 cm.sup.3/g, preferably from 0.2 to 2.0 cm.sup.3/g, more
preferably from 0.4 to 1.8 cm.sup.3/g and most preferably from 0.6
to 1.6 cm.sup.3/g, calculated from mercury porosimetry
measurement.
[0176] The intra-particle pore size of the surface-reacted calcium
carbonate preferably is in a range of from 0.004 to 1.6 .mu.m, more
preferably in a range of between 0.005 to 1.3 .mu.m, especially
preferably from 0.006 to 1.15 .mu.m and most preferably of 0.007 to
1.0 .mu.m, e.g. 0.1 to 0.6 .mu.m determined by mercury porosimetry
measurement.
[0177] According to one embodiment, a surface-reacted calcium
carbonate is provided, wherein the surface-reacted calcium
carbonate comprises a calcium carbonate-comprising material, at
least one water-insoluble calcium salt other than calcium
carbonate, and at least one water-insoluble metal cation salt.
According to one embodiment the surface-reacted calcium carbonate
comprises [0178] (i) a specific surface area of from 15 to 200
m.sup.2/g measured using nitrogen and the BET method according to
ISO 9277:2010; [0179] (ii) an intra-particle intruded specific pore
volume in the range of from 0.1 to 2.3 cm.sup.3/g calculated from
mercury porosimetry measurement; and [0180] (iii) a ratio of the at
least one water-insoluble calcium salt to calcium carbonate in the
range of from 1:99 to 99:1 by weight, and [0181] (iv) a ratio of
the at least one water-insoluble metal cation salt to calcium
carbonate in the range of from 0.00001:1 to 0.1:1 by weight.
[0182] According to one embodiment the at least one water-insoluble
calcium salt is selected from the group consisting of octacalcium
phosphate, hydroxyapatite, chlorapatite, fluorapatite, carbonate
apatite, preferably the at least one water-insoluble calcium salt
is hydroxyapatite. According to a further embodiment, the ratio of
the at least one water-insoluble calcium salt to calcium carbonate,
preferably calcite, aragonite and/or vaterite, is in the range of
from 1:9 to 9:1, preferably from 1:7 to 8:1, more preferably from
1:5 to 7:1, and even more preferably from 1:4 to 7:1 by weight.
According to an exemplary embodiment, the surface-reacted calcium
carbonate comprises a ratio of hydroxyapatitc to calcite in the
range of from 1:99 to 99:1 by weight, preferably in the range of
from 1:9 to 9:1 by weight.
[0183] According to one embodiment, the ratio of the at least one
water-insoluble metal cation salt to calcium carbonate, preferably
calcite, aragonite and/or vaterite, is in the range of from
0.0001:1 to 0.1:1 by weight, and preferably from 0.001 to 0.01 by
weight.
[0184] The surface-reacted calcium carbonate obtainable by a
process of the present invention can be provided in form of a
suspension of surface-reacted calcium carbonate, as a separated
surface-reacted calcium carbonate or as a dried surface-reacted
calcium carbonate. According to a preferred embodiment
surface-reacted calcium carbonate is a dried surface-reacted
calcium carbonate.
[0185] In case the surface-reacted calcium carbonate has been
dried, the moisture content of the dried surface-reacted calcium
carbonate can be between 0.01 and 5 wt.-%, based on the total
weight of the dried surface-reacted calcium carbonate. According to
one embodiment, the moisture content of the dried surface-reacted
calcium carbonate is less than or equal to 1.0 wt.-%, based on the
total weight of the dried surface-reacted calcium carbonate,
preferably less than or equal to 0.5 wt.-%, and more preferably
less than or equal to 0.2 wt.-%. According to another embodiment,
the moisture content of the dried surface-reacted calcium carbonate
is between 0.01 and 0.15 wt.-%, preferably between 0.02 and 0.10
wt.-%, and more preferably between 0.03 and 0.07 wt.-%, based on
the total weight of the dried surface-reacted calcium
carbonate.
[0186] The inventive surface-reacted calcium carbonate may also be
provided and/or used in form of a composition. According to one
aspect of the present invention, a composition is provided
comprising a surface-reacted calcium carbonate according to present
invention. Said composition may further comprise an additional
surface-reacted calcium carbonate, wherein the additional
surface-reacted calcium carbonate is a reaction product of natural
ground calcium carbonate or precipitated calcium carbonate with
carbon dioxide and at least one H.sub.3O.sup.+ ion donor, wherein
the carbon dioxide is formed in-situ by the H.sub.3O.sup.+ ion
donor treatment and/or is supplied from an external source.
Alternatively, or additionally other filler materials such as
natural ground calcium carbonate, precipitated calcium carbonate,
dolomite, and mixtures thereof may be present. The composition may
comprise the surface-reacted calcium carbonate according to present
invention in an amount of at least 20 wt.-%, based on the total
weight of the composition, preferably at least 40 wt.-%, more
preferably at least 60 wt.-%, and most preferably at least 80
wt.-%.
[0187] The following paragraphs are intended to refer to the
aqueous suspension of surface-reacted calcium carbonate, the
separated surface-reacted calcium carbonate as well as the dried
surface-reacted calcium carbonate.
[0188] The inventors surprisingly found that by the inventive
process a surface-reacted calcium carbonate is formed which
provides additional functionalities due to the incorporation of
metal cations into the structure of the surface-reacted calcium
carbonate. It was found that said functionalities can be tailored
for the desired application by selecting an appropriate
water-soluble metal cation source.
[0189] For example, the inventors of the present invention found
that the surface-reacted calcium carbonate may exhibit
antimicrobial activity in dry products or wet products, preferably
dry products. Therefore, the inventive surface-reacted calcium
carbonate can be used in suspensions, dispersions or slurries of
minerals, fillers or pigments, which are typically employed in the
paper, paint, rubber and plastics industries as coatings, fillers,
extenders and pigments for papermaking as well as aqueous lacquers
and paints intended for the preparation of dry or wet products,
wherein the dry products are preferred. The inventive
surface-reacted calcium carbonate may also substitute conventional
fillers completely or partially. Since both the surface-reacted
calcium carbonate is resistant to water, a long lasting
antimicrobial effect can be provided by the inventive
surface-reacted calcium carbonate. Thus, the inventive
surface-reacted calcium carbonate can even be used in articles,
which involve contact with water or aqueous liquids or are
subjected regularly to water washing, such as paints or cloths.
[0190] Moreover, it was found that the inventive surface-reacted
calcium carbonate may release minor amounts of metal cations, i.e.
in the ppm range, and thus, may be used as micronutrient delivery
agent and plant protection product on the same time. For example,
in case the metal cation is copper the surface-reacted calcium
carbonate may be used to replace conventional plant protection
products such as the Bordeaux mixture used in vineyard
treatments.
[0191] According to one embodiment, the inventive surface-reacted
calcium carbonate is used as metal cation releaser, preferably as
micronutrient delivery agent and/or plant protection product.
[0192] The surface-reacted calcium carbonate may be used for
various applications.
[0193] According to one embodiment, the surface-reacted calcium
carbonate obtainable by a process according to the present
invention or a composition comprising the same is used in polymer
applications, paper coating applications, paper making, paints,
coatings, sealants, printing inks, adhesives, food, feed,
pharmaceuticals, concrete, cement, cosmetics, water treatment,
engineered wood applications, plasterboard applications, packaging
applications and/or agricultural applications. Engineered wood
applications may comprise the use in engineered wood products such
as wood composites materials, preferably medium density fibreboards
or chipboards. Preferably the surface-reacted calcium carbonate may
be used as a dried surface-reacted calcium carbonate.
[0194] According to another embodiment, the surface-reacted calcium
carbonate obtainable by a process according to the present
invention or a composition comprising the same is used as
preservative, for the control of odour, and/or for enhancing and/or
mediating antimicrobial activity of a substrate. Preferably the
surface-reacted calcium carbonate may be used as a dried
surface-reacted calcium carbonate.
[0195] A preservative is a compound which can protect a substrate,
dry and/or wet, from spoilage and/or degradation and/or
destruction, and/or defacement and/or visible disfigurement due to
the action of microorganisms and/or prevent growth of
microorganisms on a substrate and/or in a substrate and/or prevent
contamination of a substrate by microorganisms and/or prevent
settlement of microorganisms on an substrate. According to a
preferred embodiment, the preservative acts as a
dry-film-preservative. The substrate is preferably in a solid
state, such as a paper surface, a wood surface, a wall, the surface
of a packaging material or the surface of a polymer article, but
can also be in a wet state such as in an aqueous suspension.
[0196] "Odour" according to the present invention generally is
defined as one or more volatilized chemical compounds, generally at
a very low concentration, that humans or other animals perceive by
the sense of olfaction. Accordingly, an "odorant" is a chemical
compound that has a smell or odour, i.e. is sufficiently volatile
to be transported to the olfactory system in the upper part of the
nose.
[0197] Preferred odours to be controlled according to the present
invention are odours which cause an unpleasant sensation, i.e.
malodours, but are not limited thereto. Such odours may originate
from odorants, which are preferably selected from the group
comprising odorants contained in human and animal body liquids and
secretion such as menses, blood, plasma, sanies; vaginal
secretions, mucus, milk, urine; faeces; vomit and perspiration;
odorants originating from putrefaction such as of human or animal
tissue; food such as dairy products, meat and fish and fruit such
as durian fruit.
[0198] According to one preferred embodiment of the present
invention the odorants are selected from the group consisting of
amines such as triethylamine, diethylamine, trimethylamine,
diaminobutane, tetramethylenediamine, pentamethylenediamine,
pyridine, indole, 3-methylindole; carboxylic acids such as
propionic acid, butanoic acid, 3-methylbutanoic acid,
2-methylpropanoic acid, hexanoic acid; sulphur organic compounds
such as thiols, e.g. methanethiol, phosphor organic compounds such
as methylphosphine, dimethylphosphine, their derivatives and
mixtures thereof; preferably the odorants are amines and most
preferably the odorant is diethylamine. According to an exemplified
embodiment of the present invention the odourants are diethylamine
or a thiol, for example 2-propanethiol.
[0199] The surface-reacted calcium carbonate can also be used for
enhancing and/or mediating the antimicrobial activity of a
substrate, e.g. a sheet of paper, a cardboard, a polymer material,
a paint, a wood surface, concrete, or a plant. According to a
preferred embodiment, the antimicrobial activity is against at
least one strain of bacteria and/or at least one strain of mould
and/or at least one strain of yeast and/or at least one algae.
Antimicrobial activity of a compound refers to a reduction of
growth of microorganism and/or a reduction of viable microorganisms
apparent in the presence of said compound. The expression
"enhancing the antimicrobial activity" means that the antimicrobial
activity of the substrate containing the inventive surface-reacted
calcium carbonate is higher than the antimicrobial activity
compared to a substrate not containing said filler. The expression
"for mediating the antimicrobial activity of a substrate" means
that no antimicrobial activity is apparent in a substrate without
the inventive surface-reacted calcium carbonate.
[0200] According to one embodiment, the substrate is a paper, a
cardboard, a polymer material, a paint, a wood surface, concrete,
or a plant. According to one embodiment, the polymer material is a
polymer film. A "film" in the meaning of the present invention is a
sheet or layer of material having a median thickness which is small
compared to its length and width. For example, the term "film" may
refer to a sheet or layer of material having a median thickness of
less than 200 .mu.m, but more than 1 .mu.m.
[0201] According to one embodiment the at least one strain of
bacteria is selected from the group consisting of Escherichia sp.,
Staphylococcus sp., Thermus sp., Propionibacterium sp., Rhodococcus
sp., Panninobacter sp., Caulobacter sp., Brevundimonas sp.,
Asticcacaulis sp., Sphingomonas sp., Rhizobium sp., Ensifer sp.,
Bradyrhizobium sp., Tepidimonas sp., Tepidicella sp., Aquabacterium
sp., Pelomonas sp., Alcaligenis sp., Achromobacter sp., Ralstonia
sp., Limnobacter sp., Massilia sp., Hydrogenophaga sp., Acidovorax
sp., Curvibacter sp., Delftia sp., Rhodoferax sp., Alishewanella
sp., Stenotrophomonas sp., Dokdonella sp., Methylosinus sp.,
Hyphomicrobium sp., Methylosulfomonas sp., Methylobacteria sp.,
Pseudomonas sp. such as Pseudomonas mendocina, Enterococcus sp.,
Myroides sp., Burkholderia sp., Alcaligenes sp. Staphylococcus sp.
such as Staphylococcus aurcus, Eschcrichia sp. such as Eschcrichia
coli, and mixtures thereof.
[0202] According to one embodiment the at least one strain of mould
is selected from the group comprising of Acremonium sp., Alternaria
sp., Aspergillus sp. such as Aspergillus niger, Aureobasidium sp.,
such as Aureobasidium pullulans, Cladosporium sp., Fusarium sp.,
Mucor sp., Penicillium sp., such as Penicillium funiculosum,
Rhizopus sp., Stachybotrys sp., Trichoderma sp., Dematiaceae sp.,
Phoma sp., Eurotium sp., Scopulariopsis sp., Aureobasidium sp.,
Monilia sp., Botrytis sp., Stemphylium sp., Chaetomium sp., Mycelia
sp., Neurospora sp., Ulocladium sp., Paecilomyces sp., Wallemia
sp., Curvularia sp., and mixtures thereof.
[0203] According to one embodiment the at least one strain of yeast
is selected from the group comprising Saccharomycotina,
Taphrinomycotina, Schizosaccharomycetes, Basidiomycota,
Agaricomycotina, Tremellomycetes, Pucciniomycotina,
Microbotryomycctcs, Candida sp. such as Candida albicans, Candida
tropicalis, Candida stcllatoidea, Candida glabrata, Candida krusci,
Candida guillicrmondii, Candida viswanathii, Candida lusitaniae and
mixtures thereof, Yarrowia sp. such as Yarrowia lipolytica,
Cryptococcus sp. such as Cryptococcus gattii and Cryptococcus
neofarmans, Zygosaccharomyces sp., Rhodotorula sp. such as
Rhodotorula mucilaginosa, and mixtures thereof.
[0204] According to a preferred embodiment of the present
invention, the at least one strain of bacteria is selected from the
group consisting of Escherichia coli, Staphylococcus aureus,
Pseudomonas putida, Pseudomonas mendocina, Pseudomonas oleovorans,
Pseudomonas fluorescens, Pseudomonas alcaligenes, Pseudomonas
pseudoalcaligenes, Pseudomonas entomophila, Pseudomonas syringae,
Methylobacterium extorquens, Methylobacterium radiotolerants,
Methylobacterium dichloromethanicum, Methylobacterium organophilu,
Hyphomicrobium zavarzini, Entcrococcus faccalis, Myroidcs odoratus,
Pseudomonas acruginosa, Pseudomonas orizyhabitans, Burkholderia
cepacia, Alcaligenes faecalis and Sphingomonas paucimobilis and
mixtures thereof and/or the at least one strain of mould is
selected from the group comprising of Penicillium funiculosum,
Aspergillus niger, Aureobasidium pullulans, Alternaria alternate,
Cladosporium cladosporioides, Phoma violaceae, Ulocladium atrum,
Aspergillus versicolor, Stachybotris chartarum, Penicillium
purpurogenum, Rhodotorula mucilaginosa and/or the at least one
strain of yeast is selected from the group of Candida albicans
and/or the at least one strain of alga is selected from the group
of Nostoc commune, Gloeocapsa alpicola (syn. Anacystis montana),
Klebsormidium flaccidum, Stichococcus bacillaris,
Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Navicula
pelliculosa, Anabaena flosaquae, Synechococcus leopoliensis, and
mixtures thereof.
[0205] According to still another embodiment, the surface-reacted
calcium carbonate obtained by the process of the present invention
is used for enhancing the electrical conductivity of a
substrate.
[0206] The inventive surface-reacted calcium carbonate may be
incorporated into an article in order to provide an article with
enhanced antimicrobial activity and/or enhanced electrical
conductivity. According to a further aspect of the present
invention, an article is provided comprising a surface-reacted
calcium carbonate obtainable by a process according to the present
invention or a composition comprising the same, wherein the article
is selected from paper products, engineered wood products,
plasterboard products, polymer products, hygiene products, medical
products, healthcare products, filter products, woven materials,
nonwoven materials, geotextile products, agriculture products,
horticulture products, clothing, footwear products, baggage
products, household products, industrial products, packaging
products, building products, and construction products.
[0207] The scope and interest of the invention will be better
understood based on the following examples which are intended to
illustrate certain embodiments of the present invention and are
non-limitative.
EXAMPLES
1. Measurement Methods
[0208] In the following, measurement methods implemented in the
examples are described.
Particle Size Distribution
[0209] Volume determined median particle size d.sub.50(vol) and the
volume determined top cut particle size d.sub.98(vol) was evaluated
using a Malvern Mastersizer 2000 Laser Diffraction System (Malvern
Instruments Plc., Great Britain). The d.sub.50 or d.sub.98 value,
measured using a Malvern Mastersizer 2000 Laser Diffraction System,
indicates a diameter value such that 50% or 98% by volume,
respectively, of the particles have a diameter of less than this
value. The raw data obtained by the measurement were analysed using
the Mie theory, with a particle refractive index of 1.57 and an
absorption index of 0.005.
[0210] The weight determined median particle size d.sub.50(wt) was
measured by the sedimentation method, which is an analysis of
sedimentation behaviour in a gravimetric field. The measurement was
made with a Sedigraph.TM. 5100 or 5120 of Micromeritics Instrument
Corporation, USA. The method and the instrument are known to the
skilled person and are commonly used to determine particle size
distributions of fillers and pigments. The measurement was carried
out in an aqueous solution of 0.1 wt.-% Na.sub.4P.sub.2O.sub.7. The
samples were dispersed using a high speed stirrer and
supersonicatcd.
Specific Surface Area (SSA)
[0211] The specific surface area was measured via the BET method
according to ISO 9277:2010 using nitrogen, following conditioning
of the sample by heating at 100.degree. C. under vacuum for a
period of 30 minutes. Prior to such measurements, the sample was
filtered within a Buchner funnel, rinsed with deionised water and
dried overnight at 90 to 100.degree. C. in an oven. Subsequently,
the dry cake was ground thoroughly in a mortar and the resulting
powder was placed in a moisture balance at 130.degree. C. until a
constant weight was reached.
Intra-Particle Intruded Specific Pore Volume (in Cm.sup.3/g)
[0212] The specific pore volume was measured using a mercury
intrusion porosimetry measurement using a Micromeritics Autoporc V
9620 mercury porosimeter having a maximum applied pressure of
mercury 414 MPa (60 000 psi), equivalent to a Laplace throat
diameter of 0.004 .mu.m (.about.nm). The equilibration time used at
each pressure step was 20 seconds. The sample material was sealed
in a 3 cm.sup.3 chamber powder penetrometer for analysis. The data
were corrected for mercury compression, penetrometer expansion and
sample material compression using the software Pore-Comp (Gane, P.
A. C., Kettle, J. P., Matthews, G. P. and Ridgway, C. J., "Void
Space Structure of Compressible Polymer Spheres and Consolidated
Calcium Carbonate Paper-Coating Formulations", Industrial and
Engineering Chemistry Research, 35(5), 1996, p 1753-1764).
[0213] The total pore volume seen in the cumulative intrusion data
can be separated into two regions with the intrusion data from 214
.mu.m down to about 1-4 .mu.m showing the coarse packing of the
sample between any agglomerate structures contributing strongly.
Below these diameters lies the fine inter-particle packing of the
particles themselves. If they also have intra-particle pores, then
this region appears bi-modal, and by taking the specific pore
volume intruded by mercury into pores finer than the modal turning
point, i.e. finer than the bi-modal point of inflection, the
specific intra-particle pore volume is defined. The sum of these
three regions gives the total overall pore volume of the powder,
but depends strongly on the original sample compaction/settling of
the powder at the coarse pore end of the distribution.
[0214] By taking the first derivative of the cumulative intrusion
curve the pore size distributions based on equivalent Laplace
diameter, inevitably including pore-shielding, are revealed. The
differential curves clearly show the coarse agglomerate pore
structure region, the inter-particle pore region and the
intra-particle pore region, if present. Knowing the intra-particle
pore diameter range it is possible to subtract the remainder
inter-particle and inter-agglomerate pore volume from the total
pore volume to deliver the desired pore volume of the internal
pores alone in terms of the pore volume per unit mass (specific
pore volume). The same principle of subtraction, of course, applies
for isolating any of the other pore size regions of interest.
Inductively Coupled Plasma Optical Emission Spectrometry
(ICP-OES)
[0215] Powder/filter cake were dissolved in HNO.sub.3 (69%, trace
select) and boiled for 3 minutes. After cooling, the solubilized
samples were diluted with water. The solution was then filtered
(0.2 .mu.m) and further diluted prior to analysis.
[0216] Aqueous samples were acidified with HNO.sub.3 (69%, trace
select), filtered (0.2 .mu.m) and diluted if needed prior to
analysis.
[0217] Analysis was made by ICP-OES on an Optima 3200 XL device
(Copper lines Cu 224.7, Cu 324.752, Cu 327.393).
Antimicrobial Surface Activity Test
[0218] Fresh bacteria cultures of the bacteria Staphylococcus
aureus DSM 346 strains were prepared by dilution streaking onto a
tryptic soy agar plate (TSA, no. 236950, Becton Dickinson and
Company, USA) and incubation for 16 to 20 h at 35.degree. C.
[0219] To test the antimicrobial surface activity, the Japanese
Standard Protocol JIS Z 2801 2000 was followed using fresh bacteria
prepared as described above. The plating, counting and evaluation
were done according to the Japanese Standard Protocol JIS Z 2801
2000 with the following amendments. For all coated samples, the
bacteria were released after incubation from the test item in a
petri dish using a sterile Drigalski spatula to massage the test
item with medium, instead of using a stomacher bag and massaging
the item by hand. Further for coated samples the test items were
not sterilized with 70% ethanol prior analysis.
[0220] As described in the Japanese Standard Protocol JIS Z 2801
2000, the bacterial counts are reported as colony forming units per
test item (cfu/test item) with 10 cfu/test item as limit of
detection (LOD). Thereof the antimicrobial activity (R) of the test
items was calculated as described in the Japanese Standard Protocol
JIS Z 2801 2000. For it, after 24 h incubation at 35.degree. C.,
the average number of viable bacteria on the test item (B) and the
untreated control (A) are used to calculate the antimicrobial
activity (R) using the following formula: R=log.sub.10(A/B). If
zero cfu were detected, a value of 10 cfu/test item was used for
calculation of the limit of detection of the antimicrobial
activity.
2. Mineral Materials
Surface-Reacted Calcium Carbonate SRCC 1 (Inventive)
[0221] SRCC 1 was obtained by preparing 10 litres of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground marble calcium carbonate
from Hustadmarmor Norway having a mass based particle size
distribution of 90% less than 2 .mu.m, as determined by
sedimentation, such that a solids content of 10 wt.-%, based on the
total weight of the aqueous suspension, is obtained.
[0222] In addition a solution was prepared containing 30% by mass
phosphoric acid and 1% by mass of copper sulphate pentahydrate,
CuSO.sub.4.5H.sub.2O.
[0223] Whilst mixing the slurry, 1.1 kg of the phosphoric
acid/copper sulphate solution was added to said suspension over a
period of 10 minutes at a temperature of 70.degree. C. Finally,
after the addition of the phosphoric acid, the slurry was stirred
for additional 5 minutes, before removing it from the vessel. Then,
the slurry was dewatered by use of a filter press (with a maximum
pressure of 4 bar) and dried in an oven at a temperature of
120.degree. C. until dry. The obtained surface-reacted calcium
carbonate had the following properties: d.sub.50=5.5 .mu.m,
d.sub.98=8.6 .mu.m, SSA=55.5 m.sup.2g.sup.-1. The intra-particle
intruded specific pore volume is 1.150 cm.sup.3/g (for the pore
diameter range of 0.004 to 0.43 .mu.m).
Surface-Reacted Calcium Carbonate SRCC 2 (Inventive)
[0224] SRCC 2 was obtained by preparing 10 litres of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground marble calcium carbonate
from Hustadmarmor Norway having a mass based particle size
distribution of 90% less than 2 .mu.m, as determined by
sedimentation, such that a solids content of 10 wt.-%, based on the
total weight of the aqueous suspension, is obtained.
[0225] In addition, two solutions were prepared. Solution A was
prepared such that it contained 30 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid. Solution B was
prepared by blending copper sulphate pentahydrate,
CuSO.sub.4.5H.sub.2O into a solution of phosphoric acid such that
the final solution contained 28.8 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid and 1.0 wt.-%, based on
the total weight of the aqueous solution, of copper ion.
[0226] Whilst mixing the slurry, 534 g of solution A was added to
the 10 wt.-% calcium carbonate suspension over a period of 5
minutes. Directly after solution A finished adding, 555 g of
solution B was added to the suspension over a period of 6 minutes.
Throughout the whole experiment the temperature of the suspension
was maintained at 70.degree. C. Finally, after the addition of
solution B, the suspension was stirred for additional 5 minutes
before removing it from the vessel and drying. The obtained
surface-reacted calcium carbonate had the following properties:
d.sub.50=5.4 .mu.m, d.sub.98=8.0 .mu.m, and SSA=46.4
m.sup.2g.sup.-1. The intra-particle intruded specific pore volume
was 0.98 cm.sup.3/g (for the pore diameter range of 0.004 to 0.38
.mu.m).
Surface-Reacted Calcium Carbonate SRCC 3 (Inventive)
[0227] SRCC 3 was obtained by preparing 10 litres of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground marble calcium carbonate
from Hustadmarmor Norway having a mass based particle size
distribution of 90% less than 2 .mu.m, as determined by
sedimentation, such that a solids content of 10 wt.-%, based on the
total weight of the aqueous suspension, is obtained.
[0228] In addition, two solutions were prepared. Solution A was
prepared such that it contained 30 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid. Solution B was
prepared by blending copper sulphate pentahydrate,
CuSO.sub.4.5H.sub.2O into a solution of phosphoric acid such that
the final solution contained 27.3 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid and 2.3 wt.-%, based on
the total weight of the aqueous solution, of copper ion.
[0229] Whilst mixing the slurry, 534 g of solution A was added to
the 10 wt.-% calcium carbonate suspension over a period of 5
minutes. Directly after solution A finished adding, 587 g of
solution B was added to the suspension over a period of 6 minutes.
Throughout the whole experiment the temperature of the suspension
was maintained at 70.degree. C. Finally, after the addition of
solution B, the suspension was stirred for additional 5 minutes
before removing it from the vessel and drying. The obtained
surface-reacted calcium carbonate had the following properties:
also d.sub.50=5.2 .mu.m, d.sub.98=8.1 .mu.m, SSA=30.3
m.sup.2g.sup.-1. The intra-particle intruded specific pore volume
was 1.00 cm.sup.3/g (for the pore diameter range of 0.004 to 0.30
.mu.m).
Surface-Reacted Calcium Carbonate SRCC 4 (Inventive)
[0230] SRCC 4 was obtained by preparing 10 litres of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground marble calcium carbonate
from Hustadmarmor Norway having a mass based particle size
distribution of 90% less than 2 .mu.m, as determined by
sedimentation, such that a solids content of 10 wt.-%, based on the
total weight of the aqueous suspension, is obtained.
[0231] In addition, two solutions were prepared. Solution A was
prepared such that it contained 30 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid. Solution B was
prepared by blending copper sulphate pentahydrate,
CuSO.sub.4.5H.sub.2O into a solution of phosphoric acid such that
the final solution contained 25 wt.-%, based on the total weight of
the aqueous solution, of phosphoric acid and 4.2 wt.-%, based on
the total weight of the aqueous solution, of copper ion.
[0232] Whilst mixing the slurry, 534 g of solution A was added to
the 10 wt.-% calcium carbonate suspension over a period of 6
minutes. Directly after solution A finished adding, 640 g of
solution B was added to the suspension over a period of 8 minutes.
Throughout the whole experiment the temperature of the suspension
was maintained at 70.degree. C. Finally, after the addition of
solution B, the suspension was stirred for additional 5 minutes
before removing it from the vessel and drying. The obtained
surface-reacted calcium carbonate had the following properties:
d.sub.50=5.0 .mu.m, d.sub.98=8.8 .mu.m, SSA=34.2 m.sup.2g.sup.-1.
The intra-particle intruded specific pore volume was 0.48
cm.sup.3/g (for the pore diameter range of 0.004 to 0.20
.mu.m).
Surface-Reacted Calcium Carbonate SRCC 5 (Inventive)
[0233] SRCC 5 was obtained by preparing 10 litres of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground marble calcium carbonate
from Hustadmarmor Norway having a mass based particle size
distribution of 90% less than 2 .mu.m, as determined by
sedimentation, such that a solids content of 10 wt.-%, based on the
total weight of the aqueous suspension, is obtained.
[0234] In addition, two solutions were prepared. Solution A was
prepared such that it contained 30 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid. Solution B was
prepared by blending copper sulphate pentahydrate,
CuSO.sub.4.5H.sub.2O into a solution of phosphoric acid such that
the final solution contained 25 wt.-%, based on the total weight of
the aqueous solution, of phosphoric acid and 4.2 wt.-%, based on
the total weight of the aqueous solution, of copper ion.
[0235] Whilst mixing the slurry, 534 g of solution A was added to
the 10 wt.-% calcium carbonate suspension over a period of 5
minutes. Directly after solution A finished adding, 640 g of
solution B was added to the suspension over a period of 15 minutes.
Throughout the whole experiment the temperature of the suspension
was maintained at 70.degree. C. Finally, after the addition of
solution B, the suspension was stirred for additional 5 minutes
before removing it from the vessel and drying. The obtained
surface-reacted calcium carbonate had the following properties:
d.sub.50=5.2 .mu.m, d.sub.98=8.9 .mu.m, SSA=34.8 m.sup.2g.sup.-1.
The intra-particle intruded specific pore volume was 0.49
cm.sup.3/g (for the pore diameter range of 0.004 to 0.22
.mu.m).
Surface-Reacted Calcium Carbonate SRCC 6 (Inventive)
[0236] SRCC 6 was obtained by preparing 10 litres of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground marble calcium carbonate
from Hustadmarmor Norway having a mass based particle size
distribution of 90% less than 2 .mu.m, as determined by
sedimentation, such that a solids content of 10 wt.-%, based on the
total weight of the aqueous suspension, is obtained.
[0237] In addition, two solutions were prepared. Solution A was
prepared such that it contained 30 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid. Solution B was
prepared by blending zinc chloride anhydrous, ZnCl.sub.2, into a
solution of phosphoric acid such that the final solution contained
27.3 wt.-%, based on the total weight of the aqueous solution, of
phosphoric acid and 4.4 wt.-%, based on the total weight of the
aqueous solution, of zinc ion.
[0238] Whilst mixing the slurry, 534 g of solution A was added to
the 10 wt.-% calcium carbonate suspension over a period of 5
minutes. Directly after solution A finished adding, 587 g of
solution B was added to the suspension over a period of 6 minutes.
Throughout the whole experiment the temperature of the suspension
was maintained at 70.degree. C. Finally, after the addition of
solution B, the suspension was stirred for additional 5 minutes
before removing it from the vessel and drying. The obtained
surface-reacted calcium carbonate had the following properties:
d.sub.50=5.5 .mu.m, d.sub.98=10.0 .mu.m, SSA=43.2 m.sup.2g.sup.-1)
The intra-particle intruded specific pore volume is 0.756
cm.sup.3/g (for the pore diameter range of 0.004 to 0.31
.mu.m).
Surface-Reacted Calcium Carbonate SRCC 7 (Inventive)
[0239] SRCC 7 was obtained by preparing 10 litres of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground marble calcium carbonate
from Hustadmarmor Norway having a mass based particle size
distribution of 90% less than 2 .mu.m, as determined by
sedimentation, such that a solids content of 10 wt.-%, based on the
total weight of the aqueous suspension, is obtained.
[0240] In addition, two solutions were prepared. Solution A was
prepared such that it contained 30 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid. Solution B was
prepared by blending zinc chloride anhydrous, ZnCl.sub.2, into a
solution of phosphoric acid such that the final solution contained
25 wt.-%, based on the total weight of the aqueous solution, of
phosphoric acid and 8.0 wt.-%, based on the total weight of the
aqueous solution, of zinc ion.
[0241] Whilst mixing the slurry, 534 g of solution A was added to
the 10 wt.-% calcium carbonate suspension over a period of 5
minutes. Directly after solution A finished adding, 640 g of
solution B was added to the suspension over a period of 7 minutes.
Throughout the whole experiment the temperature of the suspension
was maintained at 70.degree. C. Finally, after the addition of
solution B, the suspension was stirred for additional 5 minutes
before removing it from the vessel and drying. The obtained
surface-reacted calcium carbonate had the following properties:
d.sub.50=8.3 .mu.m, d.sub.98=19.3 .mu.m, SSA=30.1 m.sup.2g.sup.-1)
The intra-particle intruded specific pore volume is 0.740
cm.sup.3/g (for the pore diameter range of 0.004 to 0.43
.mu.m).
Surface-Reacted Calcium Carbonate SRCC 8 (Inventive)
[0242] SRCC 8 was obtained by preparing 10 litres of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground limestone calcium
carbonate from Orgon, France having a mass based median particle
size of 3 .mu.m, as determined by sedimentation, such that a solids
content of 10 wt.-%, based on the total weight of the aqueous
suspension, is obtained.
[0243] In addition, two solutions were prepared. Solution A was
prepared such that it contained 30 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid. Solution B was
prepared by blending zinc chloride anhydrous, ZnCl.sub.2, into a
solution of phosphoric acid such that the final solution contained
27.3 wt.-%, based on the total weight of the aqueous solution, of
phosphoric acid and 4.4 wt.-%, based on the total weight of the
aqueous solution, of zinc ion.
[0244] Whilst mixing the slurry, 534 g of solution A was added to
the 10 wt.-% calcium carbonate suspension over a period of 5
minutes. Directly after solution A finished adding, 587 g of
solution B was added to the suspension over a period of 6 minutes.
Throughout the whole experiment the temperature of the suspension
was maintained at 70.degree. C. Finally, after the addition of
solution B, the suspension was stirred for additional 5 minutes
before removing it from the vessel and drying. The obtained
surface-reacted calcium carbonate had the following properties:
d.sub.50=11.0 .mu.m, d.sub.98=25.3 .mu.m, SSA=27.6 m.sup.2g.sup.-1.
The intra-particle intruded specific pore volume is 0.717
cm.sup.3/g (for the pore diameter range of 0.004 to 0.75
.mu.m).
Powder 9 (Inventive)--a Mix of SRCC 3 and SRCC 11
[0245] 400 g of a 22 wt.-% solid content filter cake from sample
SRCC 3 were dispersed in 1 litres deionized water, agitated with a
mechanical stirrer for approx. 20 minutes (300-350 rpm) and then
filtered on a Buchner funnel. This procedure was repeated a second
time, and, after the second washing step, the filter cake was dried
in an oven (110.degree. C.) and deagglomerated.
[0246] 20 g of the above powder were then mixed with 180 g of SRCC
11.
Powder 10 (Inventive)--a Mix of SRCC 5 and SRCC 11
[0247] 400 g of a 24.5 wt.-% solid content filter cake from sample
SRCC 5 were dispersed in 1 L deionized water, agitated with a
mechanical stirrer for Ca. 20 minutes (300-350 rpm) and then
filtered on a Buchner funnel. This procedure was repeated a second
time, and, after the second washing step, the filter cake was dried
in an oven (110.degree. C.) and deagglomerated.
[0248] 20 g of the above powder were then mixed with 180 g of SRCC
11.
Surface-Reacted Calcium Carbonate SRCC 11 (Comparative)
[0249] SRCC 11 is a surface-reacted calcium carbonate (d.sub.50=2.6
.mu.m, BET=34.7 m.sup.2/g, and an intra-particle intruded specific
pore volume of 0.305 cm.sup.3/g (for the pore diameter range of
0.004 to 0.19 .mu.m), without further treatment.
Surface-Reacted Calcium Carbonate SRCC 12 (Inventive)
[0250] SRCC 12 was obtained by preparing 0.5 a litre of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground marble calcium carbonate
from Hustadmarmor Norway having a mass based particle size
distribution of 90% less than 2 .mu.m, as determined by
sedimentation, such that a solids content of 10 wt.-%, based on the
total weight of the aqueous suspension, is obtained.
[0251] In addition, a solution was prepared containing 29.1% by
mass phosphoric acid and 3.1% by mass of chloroplatinic acid
hexahydrate, H.sub.2PtCl.sub.6.6H.sub.2O.
[0252] Whilst mixing the slurry, 91.8 g of the phosphoric
acid/chloroplatinic acid hexahydrate solution was added to said
suspension over a period of 10 minutes at a temperature of
70.degree. C. Finally, after the addition of the phosphoric acid,
the slurry was stirred for additional 5 minutes, before removing it
from the vessel. Then, the slurry was dried by use of a rotary
evaporator. The obtained surface-reacted calcium carbonate had the
following properties: d.sub.50=8.8 .mu.m, d.sub.98=19.9 .mu.m,
SSA=53.9 m.sup.2g.sup.-1. The intra-particle intruded specific pore
volume is 1.415 cm.sup.3/g (for the pore diameter range of 0.004 to
0.67 .mu.m).
Surface-Reacted Calcium Carbonate SRCC 13 (Inventive)
[0253] SRCC 13 was obtained by preparing 0.5 a litre of an aqueous
suspension of ground calcium carbonate in a mixing vessel by
adjusting the solids content of a ground marble calcium carbonate
from Hustadmarmor Norway having a mass based particle size
distribution of 90% less than 2 .mu.m, as determined by
sedimentation, such that a solids content of 10 wt.-%, based on the
total weight of the aqueous suspension, is obtained.
[0254] In addition, two solutions were prepared. Solution A was
prepared such that it contained 30 wt.-%, based on the total weight
of the aqueous solution, of phosphoric acid. Solution B was
prepared by blending chloroplatinic acid hexahydrate,
H.sub.2PtCl.sub.6.6H.sub.2O into a solution of phosphoric acid such
that the final solution contained 28.2 wt.-%, based on the total
weight of the aqueous solution, of phosphoric acid and 2.3 wt.-%,
based on the total weight of the aqueous solution, of platinum
ion.
[0255] Whilst mixing the slurry, 44.5 g of solution A was added to
the 10 wt.-% calcium carbonate suspension over a period of 5
minutes. Directly after solution A finished adding, 47.3 g of
solution B was added to the suspension over a period of 5 minutes.
Throughout the whole experiment the temperature of the suspension
was maintained at 70.degree. C. Finally, after the addition of
solution B, the suspension was stirred for additional 5 minutes
before removing it from the vessel and drying. The obtained
surface-reacted calcium carbonate had the following properties:
also d.sub.50=8.5 .mu.m, d.sub.98=18.1 .mu.m, and SSA=57.8
m.sup.2g.sup.-1. The intra-particle intruded specific pore volume
was 1.417 cm.sup.3/g (for the pore diameter range of 0.004 to 0.67
.mu.m).
3. Analysis
TABLE-US-00001 [0256] TABLE 1 Quantitative Rietveld analyses (XRD)
SRCC 11 SRCC 3 SRCC 4 SRCC 5 Mineral Formula (comparative)
(inventive) (inventive) (inventive) Calcite CaCO.sub.3 73.7 51.2
58.5 58.8 Hydroxylapatite Ca.sub.5(OH)(PO.sub.4).sub.3 26.3 46.1
25.4 25.6 Monetite CaHPO.sub.4 -- 2.7 15.8 15.4 Brochantite
Cu.sub.4SO.sub.4(OH).sub.6 -- -- 0.3 0.2 Total 100 100 100 100 Data
were normalized to 100% crystalline material.
ICP-OES
TABLE-US-00002 [0257] TABLE 2 Composition of powder samples after
filtration. SRCC 3 SRCC 5 Cu (ICP-OES, %) 0.56 2.16
TABLE-US-00003 TABLE 3 Composition of filtered washing water from
Powder 5. 1 L washing Calcium 336 .+-. 5 ppm; ROR.sup.a): 95.0%
Copper <0.1 ppm .sup.a)ROR means rate of recovery of the
measurement.
[0258] The XRD measurements show that a new crystalline calcium
phase (monetite) has been formed in the inventive surface-reacted
calcium carbonate. Furthermore, the inventive samples SRCC4 and
SRCC5 show the presence of a copper mineral phase, namely,
brochantite. The XRD measurements of SRCC3 did not reveal a
significant copper phase. However, it could be confirmed by ICP-OES
that SRCC3 contains copper.
[0259] For the analysis according to Table 3, 400 g of SRCC 5
filter cake (corresponding to 98 g solid) are dispersed with 1
litre deionised water and agitated (mechanical agitation, ca 300
rpm) for 30 minutes. The suspension is filtered, and the filtered
solution is analysed to determine the amount of copper in 1 litre
water. It can be gathered from Table 3 that only a very low amount
of copper was leached into the water.
4. Slurries of Surface-Reacted Calcium Carbonate Fillers and Paper
Coatings
Examples 1 to 5 (E1 to E5) and Comparative Example 1 (CE1)
[0260] Slurries were prepared on a Pendraulik stirrer, by stirring
mixtures of the compositions indicated in Table 4 below for 10
minutes at room temperature with 930 rpm.
TABLE-US-00004 TABLE 4 Composition of produced filler slurries.
SRCC Water DA Solid Brookfield [parts by [parts by [parts by
content viscosity Conductivity Example SRCC weight] weight] weight]
[wt.-%] [mPas] pH [mS/cm] CE1 SRCC 11 100 100 0.7 46.7 348 9.2 1.7
E1 SRCC 1 100.sup.a 465 0.7 17.7 992 7.5 1.2 E2 SRCC 3 100.sup.b
405 0.7 19.5 1188 6.9 1.8 E3 SRCC 5 100.sup.c 435 0.7 18.7 1098 6.6
2.0 E4 Powder 9-mix of 100 125 0.7 41.4 108.4 8.9 1.8 SRCC 3 and
SRCC 11 washed (90:10 mixture) E5 Powder 10-mix 100 125 0.7 41.6
138 8.7 1.9 of SRCC 5 and SRCC 11 washed (90:10 mixture) .sup.aa
20.3 wt.-% filter cake from SRCC 1 was used. .sup.ba 24.5 wt.-%
filter cake from SRCC 3 was used. .sup.ca 24.5 wt.-% filter cake
from SRCC 5 was used. DA = dispersing agent (100%
sodium-neutralised polyacrylate, M.sub.w = 3 500 g/mol, pH =
8).
[0261] Coating colours containing 100 parts of the respective SRCC
(w/w) and 6 parts (dry/dry) of Styronal D628 (BASF, Germany) were
then prepared with slurries according to Examples 1 to 5 and
Comparative Examples 1 and coated on superYUPO.RTM. foils from
Fischer Papier AG, Switzerland (thickness 80 .mu.m, size:
18.times.26 cm.sup.2, 62 g/m.sup.2, polypropylene). The composition
of the coating colours and coating weights are summarized in Table
5 below.
TABLE-US-00005 TABLE 5 Coating colour preparation and coating
weight. Coating colour composition Styronal SRCC D628 Solid Coating
[parts by [parts, content weight Example Slurry weight] dry/dry]
[wt.-%] [g/m.sup.2] CE2 CE1 (SRCC 11) 100 6 40 12.4 E6 E1 (SRCC 1)
100 6 18 4.4 E7 E2 (SRCC 3) 100 6 18 4.6 E8 E3 (SRCC 5) 100 6 18
8.1 E9 E4 (Powder 100 6 40 14.5 9-mix of SRCC 3 and SRCC 11 washed
(90:10 mixture)) E10 E5 (Powder 100 6 40 13 10-mix of SRCC 5 and
SRCC 11 washed (90:10 mixture))
Example 11--Antimicrobial Surface Activity of Paper Coatings
[0262] The antimicrobial activity of selected paper samples
comprising a coating layer containing the surface-reacted calcium
carbonate of the present invention as filler, which were prepared
according to Examples 6 to 10 (E6 to E10) and Comparative Example 2
(CE2) was tested as described in the measurement method section
"Antimicrobial surface activity test" above.
[0263] Tables 6 shows the cfu counts per test item and the
calculated antimicrobial activity against S. aureus of the coated
paper samples E6 to E10 as well as of comparative sample CE2. The
term LOD in Table 6 refers to the limit of detection.
TABLE-US-00006 TABLE 6 Antimicrobial activity against S. aureus of
surface coated paper samples. Antimicrobial cfu/test item activity
Test item I II III Average R LOD untreated paper from 2.9 E+05 2.6
E+05 2.5 E+05 2.7 E+05 N/A N/A CE2 (SRCC 11) (before incubation)
untreated paper from 3.5 E+03 1.6 E+04 1.6 E+04 1.2 E+04 0.00 3.07
CE2 (SRCC 11) Paper from E6 (SRCC 1) 1.0 E+01 1.0 E+01 1.0 E+01 1.0
E+01 3.07 3.07 Paper from E7 (SRCC 3) 1.0 E+01 1.0 E+01 1.0 E+01
1.0 E+01 3.07 3.07 Paper from E8 (SRCC 5) 1.0 E+01 1.0 E+01 1.0
E+01 1.0 E+01 3.07 3.07 Paper from E9 (Powder 1.0 E+01 1.0 E+01 1.0
E+01 1.0 E+01 3.07 3.07 9-mix of SRCC 3 and SRCC 11 washed (90:10
mixture)) Paper from E10 (Powder 1.0 E+01 1.0 E+01 1.0 E+01 1.0
E+01 3.07 3.07 10-mix of SRCC 5 and SRCC 11 washed (90:10 mixture))
N/A: Not applicable
[0264] As can be gathered from the results compiled in Table 6
above, all paper samples with a coating layer comprising the
inventive surface-reacted calcium carbonate show good antimicrobial
activity.
* * * * *