U.S. patent application number 10/314584 was filed with the patent office on 2004-06-10 for filler-fiber composite.
This patent application is currently assigned to Specialty Minerals (Michigan) Inc.. Invention is credited to Hughes, Geoffrey Lamar.
Application Number | 20040108081 10/314584 |
Document ID | / |
Family ID | 32468506 |
Filed Date | 2004-06-10 |
United States Patent
Application |
20040108081 |
Kind Code |
A1 |
Hughes, Geoffrey Lamar |
June 10, 2004 |
Filler-fiber composite
Abstract
The present invention relates to a filler-fiber composite, a
process for its production, the use of such in the manufacture of
paper or paperboard products and to paper produced therefrom. More
particularly the invention relates to a filler-fiber composite in
which the morphology and particle size of the mineral filler are
established prior to the development of the bond to the fiber. Even
more particularly, the present invention relates to a PCC
filler-fiber composite, wherein the desired optical and physical
properties of the paper produced therefrom are realized.
Inventors: |
Hughes, Geoffrey Lamar;
(Northampton, PA) |
Correspondence
Address: |
Marvin J. Powell
Minerals Technologies Inc.
One Highland Avenue
Bethlehem
PA
18017
US
|
Assignee: |
Specialty Minerals (Michigan)
Inc.
|
Family ID: |
32468506 |
Appl. No.: |
10/314584 |
Filed: |
December 9, 2002 |
Current U.S.
Class: |
162/9 ; 106/260;
106/464; 162/158; 162/181.2; 162/181.4 |
Current CPC
Class: |
D21H 17/70 20130101;
D21H 17/675 20130101; D21H 23/04 20130101; D21H 11/16 20130101;
D21H 17/15 20130101 |
Class at
Publication: |
162/009 ;
162/158; 162/181.4; 162/181.2; 106/260; 106/464 |
International
Class: |
D21C 009/00 |
Claims
We claim:
1. A filler-fiber composite comprising: (a) feeding slake
containing citric acid to a first stage reactor (b) reacting the
slake containing citric acid in the first stage reactor in the
presence of carbon dioxide to produce a first partially converted
calcium hydroxide calcium carbonate slurry (c) reacting the first
partially converted calcium hydroxide calcium carbonate slurry in a
second stage reactor in the presence of carbon dioxide to produce a
second partially converted calcium hydroxide calcium carbonate
slurry and (d) reacting the second partially converted calcium
hydroxide calcium carbonate slurry in a third stage reactor in the
presence of carbon dioxide and fibrils to produce a filler-fiber
composite.
2. The filler-fiber composite of claim 1 wherein the fiber is from
about 0.1 microns to about 2 microns in thickness and from about 10
microns to about 400 microns in length.
3. The filler-fiber composite of claim 2 wherein the filler is
scalenohedral having a specific surface area of from about 5 meters
squared per gram to about 11 meters squared per gram.
4. The filler-fiber composite of claim 3 wherein the calcium
hydroxide calcium carbonate slurry is converted from about 20
percent to about 40 percent.
5. The filler-fiber composite of claim 4 wherein the first
partially converted calcium hydroxide calcium carbonate slurry is
converted from about 41 percent to about 99 percent.
6. The filler-fiber composite of claim 5 wherein the second
partially converted calcium hydroxide calcium carbonate slurry is
converted to a filler-fiber composite.
7. A method for producing a filler-fiber composite comprising: (a)
feeding slake containing citric acid to a first stage reactor (b)
reacting the slake containing citric acid in the first stage
reactor in the presence of carbon dioxide to produce a first
partially converted calcium hydroxide calcium carbonate slurry (c)
reacting the first partially converted calcium hydroxide calcium
carbonate slurry in a second stage reactor in the presence of
carbon dioxide to produce a second partially converted calcium
hydroxide calcium carbonate slurry and (d) reacting the second
partially converted calcium hydroxide calcium carbonate slurry in a
third stage reactor in the presence of carbon dioxide and fibers to
produce a filler-fiber composite.
8. The method of producing the filler-fiber composite of claim 7
wherein the fiber is from about 0.1 microns to about 2 microns in
thickness and from about 10 microns to about 400 microns in
length.
9. The method of producing the filler-fiber composite of claim 8
wherein the filler is scalenohedral and has a specific surface area
of from about 5 meters squared gram to about 11 meters squared per
gram.
10. The method of producing the filler-fiber composite of claim 9
wherein the calcium hydroxide calcium carbonate slurry is converted
from about 20 percent to about 40 percent.
11. The method of producing the filler-fiber composite of claim 10
wherein the first partially converted calcium hydroxide calcium
carbonate slurry is converted from about 41 percent to about 99
percent.
12. The filler-fiber composite of claim 11 wherein the second
partially converted calcium hydroxide calcium carbonate slurry is
converted to a filler-fiber composite.
13. The filler-fiber composite of claim 1 utilized in paper or
paperboard
14. The filler-fiber composite of claim 7 utilized in paper or
paperboard.
15. The paper produced utilizing the filler-fiber of claim 1.
16. The paper produced utilizing the filler-fiber of claim 7.
17. A filler-fiber composite comprising: (a) feeding slake
containing citric acid to a first stage reactor (b) reacting the
slake containing citric acid in the first stage reactor in the
presence of carbon dioxide to produce a first partially converted
calcium hydroxide calcium carbonate slurry (c) taking a first
portion of the partially converted calcium hydroxide calcium
carbonate slurry adding fibrils and reacting such in a second stage
reactor in the presence of carbon dioxide to produce a calcium
carbonate.backslash.fibril composite to serve as a heel and (d)
taking a second portion of the partially converted calcium
hydroxide calcium carbonate slurry adding fibrils and surfactant
and reacting in the presence of CO2 to produce a second partially
converted Ca(OH)2/CaCO3/fibril material and (e) reacting the second
partially converted Ca(OH)2/CaCO3/fibril material in the presence
of CO2 in a third stage reactor to produce a filler-fiber
composite.
18. The filler-fiber composite of claim 17 wherein the fiber is
from about 0.1 microns to about 2 microns in thickness and from
about 10 microns to about 400 microns in length.
19. The filler-fiber composite of claim 18 wherein the filler is
scalenohedral having a specific surface area of from about 5 meters
squared per gram to about 11 meters squared per gram.
20. The filler-fiber composite of claim 19 wherein the calcium
hydroxide calcium carbonate slurry is converted from about 20
percent to about 40 percent.
21. The filler-fiber composite of claim 20 wherein the first
partially converted calcium hydroxide calcium carbonate slurry is
converted from about 41 percent to about 99 percent.
22. The filler-fiber composite of claim 21 wherein the second
partially converted calcium hydroxide calcium carbonate slurry is
converted to a filler-fiber composite.
23. A method for producing a filler-fiber composite comprising: (a)
feeding slake containing citric acid to a first stage reactor (b)
reacting the slake containing citric acid in the first stage
reactor in the presence of carbon dioxide to produce a first
partially converted calcium hydroxide calcium carbonate slurry (c)
taking a first portion of the partially converted calcium hydroxide
calcium carbonate slurry adding fibrils and reacting such in a
second stage reactor in the presence of carbon dioxide to produce a
calcium carbonate.backslash.fibril composite to serve as a heel and
(d) taking a second portion of the partially converted calcium
hydroxide calcium carbonate slurry adding fibrils and surfactant
and reacting in the presence of CO2 to produce a second partially
converted Ca(OH)2/CaCO3/fibril material and reacting the second
partially converted Ca(OH)2/CaCO3/fibril material in the presence
of CO2 in a third stage reactor to produce a filler-fiber
composite.
24. The method for producing filler-fiber composite of claim 23
wherein the fiber is from about 0.1 microns to about 2 microns in
thickness and from about 10 microns to about 400 microns in
length.
25. The method for producing filler-fiber composite of claim 24
wherein the filler is scalenohedral having a specific surface area
of from about 5 meters squared per gram to about 11 meters squared
per gram.
26. The method for producing filler-fiber composite of claim 25
wherein the calcium hydroxide calcium carbonate slurry is converted
from about 20 percent to about 40 percent.
27. The method for producing filler-fiber composite of claim 26
wherein the first partially converted calcium hydroxide calcium
carbonate slurry is converted from about 41 percent to about 99
percent.
28. The method for producing filler-fiber composite of claim 27
wherein the second partially converted calcium hydroxide calcium
carbonate slurry is converted to a filler-fiber composite.
29. The filler-fiber composite of claim 17 utilized in paper or
paperboard
30. The filler-fiber composite of claim 23 utilized in paper or
paperboard.
31. The paper produced utilizing the filler-fiber of claim 17.
32. The paper produced utilizing the filler-fiber of claim 23.
33. A filler-fiber composite comprising: (a) feeding slake
containing citric acid to a first stage reactor (b) reacting the
slake containing citric acid in the first stage reactor in the
presence of carbon dioxide to produce a first partially converted
calcium hydroxide calcium carbonate slurry (c) taking a first
portion of the partially converted calcium hydroxide calcium
carbonate slurry adding fibrils and reacting such in a second stage
reactor in the presence of carbon dioxide to produce a calcium
carbonate/fibril composite to serve as a heel and (d) taking a
second portion of the partially converted calcium hydroxide calcium
carbonate slurry adding fibrils and polyacrylamide and reacting in
the presence of CO.sub.2 to produce a second partially converted
Ca(OH).sub.2/CaCO.sub.3/fibril material and (e) reacting the second
partially converted Ca(OH).sub.2/CaCO.sub.3/fibril material in the
presence of CO.sub.2 in a third stage reactor to produce a
filler/fiber composite.
34. The filler-fiber composite of claim 33 wherein the fiber is
from about 0.1 microns to about 2 microns in thickness and from
about 10 microns to about 400 microns in length.
35. The filler-fiber composite of claim 34 wherein the filler is
scalenohedral having a specific surface area of from about 5 meters
squared per gram to about 11 meters squared per gram.
36. The filler-fiber composite of claim 35 wherein the calcium
hydroxide calcium carbonate slurry is converted from about 20
percent to about 40 percent.
37. The filler-fiber composite of claim 36 wherein the first
partially converted calcium hydroxide calcium carbonate slurry is
converted from about 41 percent to about 99 percent.
38. The filler-fiber composite of claim 37 wherein the second
partially converted calcium hydroxide calcium carbonate slurry is
converted to a filler-fiber composite.
39. A method of producing a filler-fiber composite comprising: (a)
feeding slake containing citric acid to a first stage reactor (b)
reacting the slake containing citric acid in the first stage
reactor in the presence of carbon dioxide to produce a first
partially converted calcium hydroxide calcium carbonate slurry (c)
taking a first portion of the partially converted calcium hydroxide
calcium carbonate slurry adding fibrils and reacting such in a
second stage reactor in the presence of carbon dioxide to produce a
calcium carbonate.backslash.fibril composite to serve as a heel and
(d) taking a second portion of the partially converted calcium
hydroxide calcium carbonate slurry adding fibrils and
polyacrylamide and reacting in the presence of CO.sub.2 to produce
a second partially converted Ca(OH).sub.2/CaCO.sub.3/fibril
material and (e) reacting the second partially converted
Ca(OH).sub.2/CaCO.sub.3/fibri- l material in the presence of
CO.sub.2 in a third stage reactor to produce a filler/fiber
composite.
40. The method for producing filler-fiber composite of claim 39
wherein the fiber is from about 0.1 microns to about 2 microns in
thickness and from about 10 microns to about 400 microns in
length.
41. The method for producing filler-fiber composite of claim 40
wherein the filler is scalenohedral having a specific surface area
of from about 5 meters squared per gram to about 11 meters squared
per gram.
42. The method for producing filler-fiber composite of claim 41
wherein the calcium hydroxide calcium carbonate slurry is converted
from about 20 percent to about 40 percent.
43. The method for producing filler-fiber composite of claim 42
wherein the first partially converted calcium hydroxide calcium
carbonate slurry is converted from about 41 percent to about 99
percent.
44. The method for producing filler-fiber composite of claim 43
wherein the second partially converted calcium hydroxide calcium
carbonate slurry is converted to a filler-fiber composite.
45. The filler-fiber composite of claim 33 utilized in paper or
paperboard
46. The filler-fiber composite of claim 39 utilized in paper or
paperboard.
47. The paper produced utilizing the filler-fiber of claim 33.
48. The paper produced utilizing the filler-fiber of claim 39.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a filler-fiber composite, a
process for its production, the use of such in the manufacture of
paper or paperboard products and to paper produced therefrom. More
particularly the invention relates to a filler-fiber composite in
which the morphology and particle size of the mineral filler are
established prior to the development of the bond to the fiber. Even
more particularly, the present invention relates to a PCC
filler-fiber composite, wherein the desired optical and physical
properties of the paper produced therefrom are realized.
BACKGROUND OF THE INVENTION
[0002] Loading particulate fillers such as calcium carbonate, talc
and clay on fibers for the subsequent manufacture of paper and
paper products continues to be a challenge. A number of methods,
having some degree of success, have been used to address this
issue. To insure that fillers remain with or within the fiber web,
retention aids have been used, direct precipitation onto the fibers
have been used, a method to attach the filler directly to the
surface of the fiber have been used, mixing the fiber and the
filler have been used, precipitation within never dried pulp have
been used, a method for filling the cellulosic fiber have been
used, high shear mixing have been used, fiberous material and
calcium carbonate have been reacted with carbon dioxide in a closed
pressurized container, fillers have been trapped by mechanical
bonding, cationically charged polymers have been used and pulp
fiber lumen loaded with calcium carbonate have all been used to
retain filler in fiber for subsequent use in paper. Most of the
methods for fiber retention are both expensive and ineffective.
[0003] Therefore, what is needed is a filler fiber composite and a
method for producing the same that is both effective in retaining
the filler and inexpensive for the paper maker to utilize.
[0004] Therefore, an object of the present invention is to produce
a filler-fiber composite. Another object of the present invention
is to provide a method for producing a filler-fiber composite.
While another object of the present invention is to produce a
filler-fiber composite that maintains physical properties such as
tensile strength, breaking length and internal bond strength. Still
a further object of the present invention is to produce a
filler-fiber composite that maintains optical properties such as
ISO opacity and pigment scatter. While still a further object of
the present invention is to provide a filler-fiber composite that
is particularly useful in paper and paperboard products.
RELATED ART
[0005] U.S. Pat. No. 6,156,118 teaches mixing a calcium carbonate
filler with noil fibers in a size of P50 or finer.
[0006] U.S. Pat. No. 5,096,539 teaches in-situ precipitation of an
inorganic filler with never dried pulp.
[0007] U.S. Pat. No. 5,223,090 teaches a method for loading
cellulosic fiber using high shear mixing of crumb pulp during
carbon dioxide reaction.
[0008] U.S. Pat. No. 5,665,205 teaches a method for combining a
fiber pulp slurry and an alkaline salt slurry in the contact zone
of a reactor and immediately contacting the slurry with carbon
dioxide and mixing so as to precipitate filler onto secondary pulp
fibers.
[0009] U.S. Pat. No. 5,679,220 teaches a continuous process for
in-situ deposition of fillers in papermaking fibers in a flow
stream in which shear is applied to the gaseous phase to complete
the conversion of calcium hydroxide to calcium carbonate
immediately.
[0010] U.S. Pat. No. 5,122,230 teaches process for modifying
hydrophilic fibers with a substantially water insoluble inorganic
substance in-situ precipitation.
[0011] U.S. Pat. No. 5,733,461 teaches a method for recovery and
use of fines present in a waste water stream produced in a paper
manufacturing process.
[0012] U.S. Pat. No. 5,731,080 teaches in-situ precipitation
wherein the majority of a calcium carbonate trap the microfiber by
reliable and non-reliable mechanical bonding without binders or
retention aids.
[0013] U.S. Pat. No. 5,928,470 teaches method of making metal oxide
or metal hydroxide-modified cellulosic pulp.
[0014] U.S. Pat. No. 6,235,150 teaches a method of producing a pulp
fiber lumen loaded with calcium carbonate having a particle size of
0.4 microns to 1.5 microns.
[0015] The problem of insuring that filler materials, such as
calcium carbonate, ground calcium carbonate, clay and talc, remain
within fibers that are ultimately to be used in paper has been
subjected to a number of proofs. However, none of the prior related
art discloses a filler fiber composite where the morphology of the
filler is predetermined prior to introducing fibers, a method for
its production nor its use in paper or paper products.
SUMMARY OF THE INVENTION
[0016] The present invention relates to a filler-fiber composite
including feeding slake containing seed to a first stage reactor,
reacting the slake containing seed in the first stage reactor in
the presence of carbon dioxide to produce a first partially
converted calcium hydroxide calcium carbonate slurry, reacting the
first partially converted calcium hydroxide calcium carbonate
slurry in a second stage reactor in the presence of carbon dioxide
to produce a second partially converted calcium hydroxide calcium
carbonate slurry and reacting the second partially converted
calcium hydroxide calcium carbonate slurry in a third stage reactor
in the presence of carbon dioxide and fibers to produce a
filler-fiber composite.
[0017] In another aspect, the present invention relates to a
filler-fiber composite including feeding slake containing seed to a
first stage reactor, reacting the slake containing seed in the
first stage reactor in the presence of carbon dioxide to produce a
first partially converted calcium hydroxide calcium carbonate
slurry and reacting the first partially converted calcium carbonate
slurry in a second stage reactor in the presence of carbon dioxide
and fibers to produce a filler-fiber composite.
[0018] In a further aspect, the present invention relates to a
filler-fiber composite including feeding slake containing citric
acid to a first stage reactor, reacting the slake containing citric
acid in the first stage reactor in the presence of carbon dioxide
to produce a first partially converted calcium hydroxide calcium
carbonate slurry, reacting the first partially converted calcium
hydroxide calcium carbonate slurry in a second stage reactor in the
presence of carbon dioxide to produce a second partially converted
calcium hydroxide calcium carbonate slurry, and reacting the second
partially converted calcium hydroxide calcium carbonate slurry in a
third stage reactor in the presence of carbon dioxide and fibers to
produce a filler-fiber composite.
[0019] In yet a further aspect, the present invention relates to a
filler-fiber composite Including feeding slake containing citric
acid to a first stage reactor, reacting the slake containing citric
acid in the first stage reactor in the presence of carbon dioxide
to produce a first partially converted calcium hydroxide calcium
carbonate slurry, taking a first portion of the partially converted
calcium hydroxide calcium carbonate slurry adding fibers and
reacting such in a second stage reactor in the presence of carbon
dioxide to produce a calcium carbonate.backslash.fiber composite to
serve as a heel and taking a second portion of the partially
converted calcium hydroxide calcium carbonate slurry adding fibers
and surfactant and reacting in the presence of CO.sub.2 to produce
a second partially converted Ca(OH).sub.2/CaCO.sub.3/fiber material
and reacting the second partially converted
Ca(OH).sub.2/CaCO.sub.3/fiber material in the presence of CO.sub.2
in a third stage reactor to produce a filler-fiber composite.
[0020] In still a further aspect, the present invention relates to
a filler-fiber composite including feeding slake containing citric
acid to a first stage reactor, reacting the slake containing citric
acid in the first stage reactor in the presence of carbon dioxide
to produce a first partially converted calcium hydroxide calcium
carbonate slurry, taking a first portion of the partially converted
calcium hydroxide calcium carbonate slurry adding fibers and
reacting such in a second stage reactor in the presence of carbon
dioxide to produce a calcium carbonate/fiber composite to serve as
a heel and taking a second portion of the partially converted
calcium hydroxide calcium carbonate slurry adding fibers and
polyacrylamide and reacting in the presence of CO.sub.2 to produce
a second partially converted Ca(OH).sub.2/CaCO.sub.3/fiber material
and reacting the second partially converted
Ca(OH).sub.2/CaCO.sub.3/fiber material in the presence of CO.sub.2
in a third stage reactor to produce a filler-fiber composite.
[0021] In a final aspect, the present invention relates to a
filler-fiber composite including feeding slake containing citric
acid to a first stage reactor, reacting the slake containing citric
acid in the first stage reactor in the presence of carbon dioxide
to produce a CaCO.sub.3 heel and adding slake containing sodium
carbonate to the heel material of the first stage reactor in the
presence of CO.sub.2 to produce a partially converted calcium
hydroxide calcium carbonate slurry and reacting the partially
converted calcium hydroxide calcium carbonate slurry in a second
stage reactor in the presence of carbon dioxide and fibers to
produce a filler-fiber composite.
[0022] Fiber as used in the present invention is defined as fiber
produced by refining (any pulp refiner known in the pulp processing
industry) cellulose and/or mechanical pulp fiber. The fibers are
typically 0.1 to 2 microns in thickness and 10 to 400 microns in
length and are additionally prepared according to U.S. Pat. No.
6,251,222, which is by this reference incorporated herein.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Precipitation of PCC with Varying Morphologies
[0024] Continuous Flow Stir Tank Reactor (CFSTR)
[0025] Scalenohedral Morphology
[0026] The first step in this process involves making a high
reactive Ca(OH).sub.2 milk-of-lime slake and screening it at -325
mesh. This slake is then added to an agitated reactor, brought to a
desired reaction temperature, 0.1 percent citric acid is added to
the slake to inhibit aragonite formation, and reacted with CO.sub.2
gas. The reaction proceeds 10 percent to 40 percent of the way
through at which point the reaction is stopped. This produces a
partially converted Ca(OH).sub.2/CaCO.sub.3 slurry (approximately
20 percent solids by weight) which is then fed into a reaction
vessel at a rate that matches CO.sub.2 gassing to maintain a given
conductivity (ionic saturation) to produce a scalenohedral crystal.
This reaction proceeds until stabilization of the process is
achieved. The product made once stabilization is achieved
(approximately 95 percent converted) is then mixed with diluted
fibers (approximately 1.5 percent concentration) and water. This
mixture is then reacted with CO.sub.2 gas to endpoint pH 7.0. The
product manufactured using this method can contain from about 0.2
percent to about 99.8 percent scalenohedral PCC with respect to
fibers at 3 percent to 5 percent total solids.
[0027] The product has a specific surface area from about 5 meters
squared per gram to about 11 meters squared per gram; product
solids from about 3 percent to about 5 percent and a PCC content
from about 0.2 percent to about 99.8 percent, and is predominantly
scalenohedral in morphology.
[0028] Aragonitic Morphology
[0029] The first step in this process involves making a high
reactive Ca (OH).sub.2 milk-of-lime slake and screened at -325
mesh. The concentration of this slake is approximately 15 percent
by weight. This slake is then added to an agitated reactor, brought
to a desired reaction temperature, from about 0.05 percent to about
0.04 percent additive is added to direct morphology and size, and
reacted with CO.sub.2 gas. The reaction proceeds 10 percent to 40
percent of the way through at which point the reaction is stopped.
This produces a partially converted Ca (OH).sub.2/CaCO.sub.3 slurry
which is then fed into a reaction vessel at a rate that matches
CO.sub.2 gassing to maintain a given conductivity (ionic
saturation) to produce an acicular, aragonitic crystal. The
reaction continues until process stabilization is achieved. The
product made once stabilization is achieved, (approximately 95
percent calcium carbonate) is mixed with diluted fibers
(approximately 1.5 percent concentration) and water. The calcium
carbonate and fibers are then reacted with CO.sub.2 gas to an
endpoint of pH 7.0. The product manufactured using this method
contains from about 0.2 percent to about 99.8 percent aragonitic
PCC with respect to the fibers at about 3 percent to about 5
percent total solids.
[0030] The product has a specific surface area of about 5 meters
squared per gram to about 8 meters squared per gram; product solids
from about 3 percent to about 5 percent by weight and a PCC content
from about 0.2 percent to about 99.8 percent with respect to fibers
and has a predominantly aragonitic morphology.
[0031] Rhombohedral Morphology
[0032] The first step in this process involves making a high
reactive Ca (OH).sub.2 milk-of-lime slake which is screened at -325
mesh and has a concentration of approximately 20 percent by weight.
0.1 percent citric acid is added to inhibit aragonite formation. A
portion of this slake is added to an agitated reactor, brought to a
desired reaction temperature and carbonated with CO.sub.2 gas. The
reaction proceeds to conductivity minimum producing a "heel". A
"heel" is defined as a fully converted calcium carbonate crystal
with average particle size typically in the range of about 1 micron
to about 2.5 micron with any crystal morphology. Sodium carbonate
is added to the remainder of the slake not used in the manufacture
of the "heel" material. This slake and CO.sub.2 is added to the
"heel" material at a CO.sub.2 gassing rate to maintain a given
conductivity (ionic saturation) to produce a rhombohedral crystal.
The reaction is continued until process stabilization is achieved.
Once stabilization is achieved, this product (approximately 90
percent to 95 percent converted) is mixed with diluted fibers
(approximately 1.5 percent concentration) and water. Additional
CO.sub.2 is added to an endpoint of pH 7.0. The product
manufactured using this method contains from about 0.2 percent to
about 99.8 percent rhombohedral PCC with respect to fibers and is
about 3 percent to about 5 percent total solids.
[0033] The product has a specific surface area from about 5 meters
squared per gram to about 8 meters squared per gram; product solids
from about 3 percent to about 5 percent; and PCC content from about
0.2 percent to about 99.8 percent and has a predominantly
rhombohedral morphology:
EXAMPLES
[0034] The following examples are intended to exemplify the
invention and are not intended to limit the scope of the
invention.
Example 1
[0035] Scalenohedral PCC
[0036] Reacted 15 liters of water with 3 kilogram CaO at 50 degrees
Celsius producing a 20 percent by weight Ca(OH).sub.2 slake. The
Ca(OH).sub.2 slake was then screened at -325 mesh producing a
screened slake that was transferred to a first 30-liter double
jacketed stainless steel reaction vessel with an agitation of 615
revolutions per minute (rpm). 0.1 percent citric acid, by weight of
total theoretical CaCO.sub.3 to be produced, was added to the
screened slake in a 30-liter reaction vessel and the temperature of
the contents brought to 40 degrees Celsius. Began addition of 20
percent CO.sub.2 gas in air (14.83 standard liter minute
CO.sub.2/59.30 standard liter minute air) to the 30-liter reaction
vessel to produce a 2:1 Ca (OH).sub.2/CaCO.sub.3 slurry. At this
point, CO.sub.2 gassing was stopped and the slurry was transferred
to an agitated 20-liter storage vessel.
[0037] 2 liters of the 2:1 Ca(OH).sub.2/CaCO.sub.3 slurry was
transferred to a first 4-liter agitated (1250 rpm) stainless steel,
double jacketed reaction vessel. The temperature was brought to 51
degrees Celsius and 20 percent CO.sub.2 gas in air (1.41 standard
liter minute CO.sub.2/5.64 standard liter minute air) was added to
the first 4-liter reaction vessel until a pH of 7.0 was achieved
producing a CaCO.sub.3 slurry. Once a pH 7.0 was achieved began
addition of the 2:1 Ca(OH).sub.2/CaCO.sub.3 slurry of the 20-liter
storage vessel to the first 4-liter reaction vessel while
continuing to add 20 percent CO.sub.2 gas in air (1.41 standard
liter minute CO.sub.2/5.64 standard liter minute air) to the first
4-liter reaction vessel to maintain a conductivity of approximately
90 percent ionic saturation. The addition of
Ca(OH).sub.2/CaCO.sub.3 slurry and CO.sub.2 to the first 4-liter
reaction vessel was continued for approximately 12 hours until
product physical properties remained essentially unchanged,
producing a CaCO.sub.3 slurry that was approximately 98 percent
converted. Transferred 0.18 liters of the 98 percent CaCO.sub.3
slurry to a second 4-liter agitated (1250 rpm), stainless steel,
double jacketed reaction vessel, added 0.66 liters of 3.8 percent
by dry weight cellulosic fibers and diluted to 1.5 percent
consistency. This mixture of CaCO.sub.3 slurry and fiber was
reacted with 20 percent CO.sub.2 in air (1.41 standard liter minute
CO.sub.2/5.64 standard liter minute air) to produce a CaCO.sub.3
filler-fiber composite. The calcium carbonate filler had a
predominantly scalenohedral morphology.
Example 2
[0038] Aragonitic PCC
[0039] Reacted 10.5 liters of water with 2.1 kilograms CaO at 50
degrees Celsius producing a 15 percent by weight Ca(OH).sub.2
slake. The Ca(OH).sub.2 slake was then screened at -325 mesh
producing a screened slake that was transferred to a 30-liter
double jacketed stainless steel reaction vessel with an agitation
of 615rpm. Added 0.1 percent by weight of a high surface area
(HSSA) aragonitic seed (surface area .about.40 meters squared per
gram, approximately 25 percent solids) to the 30-liter reaction
vessel and brought the temperature of the contents to 51 degrees
Celsius. A "seed" is defined as a fully converted aragonitic
crystal that has been endpointed and milled to a high specific
surface area (i.e. greater than 30 meters squared per gram and
typically a particle size of 0.1 to 0.4 microns). Began addition of
10 percent CO.sub.2 gas in air (5.24 standard liter minute
CO.sub.2/47.12 standard liter minute air) to the 30-liter stainless
steel, double jacketed reaction vessel for a 15-minute period after
which the CO.sub.2 concentration was increased to 20 percent in air
(10.47 standard liter minute CO.sub.2/41.89 standard liter minute
air) for an additional 15 minutes producing a 2.3:1 Ca
(OH).sub.2/CaCO.sub.3 slurry. At which time CO.sub.2 gassing was
stopped. The 2.3:1 Ca(OH).sub.2/CaCO.sub.3 slurry was transferred
to an agitated 20-liter storage vessel. Transferred 2 liters of the
2.3:1 Ca(OH).sub.2/CaCO.sub.3 slurry to a first 4-liter agitated,
double jacketed stainless steel reaction vessel with agitation set
at 1250rpm and the temperature was brought to 52 degrees Celsius.
Began addition of 20 percent CO.sub.2 gas in air (1.00 standard
liter minute CO.sub.2/3.99 standard liter minute air) to the first
4-liter reaction vessel and the reaction was continued until a pH
of 7.0 was achieved producing a 100 percent CaCO.sub.3 slurry. The
temperature of the 100 percent CaCO.sub.3 slurry of the first
4-liter reaction vessel was brought to 63 degrees Celsius. Began
addition of the 2.3:1 Ca(OH).sub.2/CaCO.sub.3 slurry of the
20-liter storage vessel to the first 4-liter reaction vessel while
continuing to add 20 percent CO.sub.2 in air (1.00 standard liter
minute CO.sub.2/3.99 standard liter minute air) to the first
4-liter reaction vessel maintaining a conductivity of approximately
90 percent ionic saturation. Continued the reaction for
approximately 9 hours until the physical properties of the
resultant product remained essentially unchanged, producing a 98
percent by wt. CaCO.sub.3 slurry.
[0040] Transferred 0.35 liters of the 98 percent CaCO.sub.3 slurry
to a second 4-liter agitated (1250 rpm), stainless steel, double
jacketed reaction vessel, added 0.66 liters of 3.8 percent by wt.
cellulosic fiber and 1.0 liters water to the second 4-liter reactor
producing a 1.5 percent by wt. CaCO.sub.3/fiber mixture. Added an
additional 20 percent CO.sub.2 in air (1.00 standard liter minute
CO.sub.2/3.99 standard liter minute air) to the second 4-liter
reaction vessel until a pH of 7.0 was reached at which time the
reaction was completed producing a CaCO.sub.3/fiber composite. The
composite consisted of approximately 75 percent aragonitic PCC to
fiber.
Example 3
[0041] Rhombohedral PCC
[0042] Reacted 15 liters of water with 3 kilograms CaO at 50
degrees Celsius producing a 20 percent by weight Ca(OH).sub.2
slake. The Ca(OH).sub.2 slake was screened at -325 mesh producing a
screened slake that was transferred to an agitated 20-liter storage
vessel. Transferred 2-liters of the screened slake from the
20-liter storage vessel to a first 4-liter agitated, stainless
steel, double jacketed reaction vessel and began agitation at 1250
rpm. Added 0.03 percent citric acid by weight of theoretical
CaCO.sub.3 to the first 4-liter reaction vessel and raised the
temperature of the contents to 50 degrees Celsius. Added 20 percent
CO.sub.2 gas in air (1.44 standard liter minute CO.sub.2/5.77
standard liter minute air) to the first 4-liter reaction vessel
until a pH of 7.0 was achieved producing a 100 percent CaCO.sub.3
slurry. To the screened slake in the 20-liter storage vessel, added
a solution of 1.3 percent by weight of Na.sub.2CO.sub.3, based on
theoretical yield of CaCO.sub.3, producing a
Ca(OH).sub.2/Na.sub.2CO.sub.3 slake. Increased the temperature of
the contents of the first 4-liter reaction vessel to approximately
68 degrees Celsius and began addition of the
Ca(OH).sub.2/Na.sub.2CO.sub.3 slake of the 20-liter storage vessel
to the first 4-liter reaction vessel while continuing to add 20
percent CO.sub.2 in air (1.44 standard liter minute CO.sub.2/5.77
standard liter minute air) to the first 4-liter reaction vessel
maintaining a conductivity of approximately 50 percent ionic
saturation. Addition of the Ca(OH).sub.2/Na.sub.2CO.sub.3 slake and
CO.sub.2 was continued for approximately 12 hours until physical
properties of the resultant product remained essentially unchanged
producing an approximate 98 percent by wt. CaCO.sub.3 slurry.
[0043] Transferred 0.22 liters of the 98 percent CaCO.sub.3 slurry
to a second 4-liter agitated (1250 rpm) dual jacketed, stainless
steel reaction vessel and added 0.66 liters of 3.8 percent by
weight cellulosic fiber and 1.0 liters water to the second 4-liter
reactor producing a 1.5 percent by weight CaCO.sub.3/fiber mixture.
Added an additional 20 percent CO.sub.2 in air (1.44 standard liter
minute CO.sub.2/5.77 standard liter minute air) to the second
4-liter reaction vessel until a pH of 7.0 was reached at which time
the reaction was completed producing an approximate 3.4 percent by
wt CaCO.sub.3/fiber composite. The calcium carbonate had a
predominantly rhombohedral morphology.
Example 4
[0044] Scalenohedral--CFSTR
[0045] Reacted 15 liters of water with 3 kilograms CaO at 48
degrees Celsius to produce a Ca(OH).sub.2 slake, added an
additional 6 liters of water producing a 20 percent by weight
Ca(OH).sub.2 slake. The 20 percent Ca(OH).sub.2 slake was screened
at -325 mesh and transferred to a 30-liter double jacketed,
stainless steel reaction vessel with an agitation of 615rpm. Added
0.015 percent citric acid, by weight of total theoretical
CaCO.sub.3 to be produced, to the 30-liter reaction vessel and the
temperature of the contents brought to 36 degrees Celsius. Began
addition of 20 percent CO.sub.2 gas in air (13.72 standard liter
minute CO.sub.2/54.89 standard liter minute air) to the 30-liter
reaction vessel to produce a 5:1 Ca(OH).sub.2/CaCO.sub.3 slurry.
CO.sub.2 gassing was stopped and the Ca(OH).sub.2/CaCO.sub.3 slurry
was transferred to an agitated 20-liter storage vessel.
[0046] In a 4-liter agitated storage vessel, combined 0.25 liters
of the Ca(OH).sub.2/CaCO.sub.3 slurry with 0.66 liters of 3.8
percent by weight fibers and with 1.09 liters of water making a
Ca(OH).sub.2/CaCO.sub.3/fib- er material. Transferred 2 liters of
the Ca(OH).sub.2/CaCO.sub.3/fiber material to a 4-liter agitated
(1250 revolutions per minute) reaction vessel and the temperature
brought to 55 degrees Celsius and carbonated with 20 percent
CO.sub.2 in air (1.30 standard liter minute CO.sub.2/5.23 standard
liter minute air) to a pH of 7.0 producing a CaCO.sub.3/fiber
composite. Prepared 16-liters of 1.5 percent by weight fibers and a
separate 10-liter vessel of water. To the 4-liter reaction vessel
began addition of the Ca(OH).sub.2/CaCO.sub.3 slurry of the
20-liter agitated storage vessel, along with the 1.5 percent
consistency fiber mixture at 172.05 ml per minute, along with 31.21
ml per minute of additional water while maintaining the flow of
CO.sub.2 gas (1.30 standard liter minute CO.sub.2/5.23 standard
liter minute air) at a rate to maintain conductivity of
approximately 90 percent ionic saturation, while maintaining mass
balance of approximately 4 percent to 5 percent total solids.
[0047] This reaction was continued until product physical
properties remained essentially unchanged. Addition of material
from the storage vessel was stopped while CO.sub.2 addition was
continued and the material in the 4-liter agitated reaction vessel
was brought to a pH of 7.0 at which time CO.sub.2 addition was
stopped producing a 2.2:1 CaCO.sub.3/fiber composite with the
CaCO.sub.3 having a well defined scalenohedral morphology.
Example 5
[0048] Scalenohedral CFSTR/Surfactant
[0049] Reacted 15 liters of water with 3 kilograms CaO at 48
degrees Celsius to produce a Ca(OH).sub.2 slake, added an
additional 6 liters of water producing a 20 percent by weight
Ca(OH).sub.2 slake. The 20 percent Ca(OH).sub.2 slake was screened
at -325 mesh and transferred to a 30-liter reaction vessel (615
revolutions per minute). Added 0.015 percent citric acid, by weight
of total theoretical CaCO3 to be produced, to the 30-liter reaction
vessel and the temperature of the contents brought to 35 degrees
Celsius. Began addition of 20 percent CO.sub.2 gas in air (14.08
standard liter minute CO.sub.2/56.30 standard liter minute air) to
the 30-liter reaction vessel producing a 5:1
Ca(OH).sub.2/CaCO.sub.3 slurry. At this point, CO.sub.2 gassing was
stopped and the Ca(OH).sub.2/CaCO.sub.3 slurry was transferred to a
20-liter agitated storage vessel.
[0050] In a 4-liter agitated storage vessel, combined 0.25 liters
of the Ca(OH).sub.2/CaCO.sub.3 slurry with 0.66 liters of 3.8
percent by weight fibers and with 1.09 liters of water making 2
liters of Ca(OH).sub.2/CaCO.sub.3/fiber material.
[0051] Transferred 2 liters of the Ca(OH).sub.2/CaCO.sub.3/fiber
material to a 4-liter stainless steel, double jacketed, agitated
(1250 revolutions per minute) reaction vessel and the temperature
was brought to 58 degrees Celsius. Reacted the
Ca(OH).sub.2/CaCO.sub.3/fiber material with 20 percent CO.sub.2 in
air (1.30 standard liter minute CO.sub.2/5.23 standard liter minute
air) to a pH of 7.0.
[0052] At this point, prepared 16-liters of 1.5 percent by weight
fibers (6.32 liters of fibers at 3.8 percent consistency and 9.68
liters of water) and a separate 10-liter vessel of water. Added
0.04 percent surfactant based on the volume of fibers at 1.5
percent consistency. The surfactant is Tergitol.TM. MIN-FOAM
2.times. which is available commercially from Union Carbide, 39 Old
Ridgebury Road, Danbury, Conn. 06817.
[0053] Once a pH of 7.0 was achieved in the 4-liter reaction
vessel, began addition of the remaining 5:1 Ca(OH).sub.2/CaCO.sub.3
slurry from the 20-liter agitated storage vessel, with a flow of
the 1.5 percent fiber mixture at 176.48 ml per minute and with
32.00 ml per minute water from the 10-liter vessel to the 4-liter
reaction vessel while maintaining the flow of CO.sub.2 gas (1.30
standard liter minute CO.sub.2/5.23 standard liter minute air) at a
rate to maintain conductivity of approximately 90 percent ionic
saturation, while maintaining mass balance of approximately 4
percent to 5 percent total solids. Continued addition of the
material from the agitated storage vessel to the reaction vessel
until product physical properties remained essentially unchanged.
At which point, addition of material from the storage vessel was
stopped while CO.sub.2 addition was continued to a pH of 7.0 at
which time CO.sub.2 addition was stopped. This produced a 2.33:1
CaCO.sub.3/fiber composite with the calcium carbonate having a well
defined scalenohedral morphology.
Example 6
[0054] Scalenohedral CFSTR/Polyacrylamide
[0055] Reacted 15 liters of water with 3 kilograms CaO at 48
degrees Celsius producing a Ca(OH).sub.2 slake, added an additional
6 liters of water producing a 20 percent by weight Ca(OH).sub.2
slake. The 20 percent Ca(OH).sub.2 slake was then screened at -325
mesh producing a screened slake that was transferred to a 30-liter
agitated (615 rpm) reaction vessel. Added 0.1 percent citric acid,
by weight of total theoretical CaCO.sub.3 to be produced, to the
30-liter reaction vessel and the temperature of the contents
brought to 50 degrees Celsius. Began addition of 20 percent
CO.sub.2 gas in air (15.01 standard liter minute CO.sub.2/60.06
standard liter minute air) to the 30-liter reaction vessel
producing a 5:1 Ca(OH).sub.2/CaCO.sub.3 slurry. CO.sub.2 gassing
was stopped and the slurry was transferred to a 20-liter agitated
storage vessel. To a 4-liter agitated vessel added 0.31 liters of
the Ca(OH).sub.2/CaCO.sub.3 slurry, 0.60 liters of fibers at 3.8
percent consistency and 1.09 liters of water to produce a
Ca(OH).sub.2/CaCO.sub.3- /fiber material. 2 liters of the
Ca(OH).sub.2/CaCO.sub.3/fiber material was transferred to a 4-liter
agitated (1250 revolutions per minute) reaction vessel and the
temperature was brought to 51 degrees Celsius. Began addition of 20
percent CO.sub.2 in air (1.34 standard liter minute CO.sub.2/5.34
standard liter minute air) until a pH of 7.0 was reached producing
a CaCO.sub.3/fiber composite.
[0056] At this point, prepared 16-liters of 1.5 percent by weight
fibers (6.32 liters of fibers at 3.8 percent consistency and 9.68
liters of water) and a separate 10-liter vessel of water. Added
0.05 percent cationic polyacrylamide (Percol 292) based on the
volume of fibers at 1.5 per cent consistency. Percol 292 is
commercially available from Allied Colloids, 2301 Wilroy Road,
Suffolk, Va. 23434.
[0057] Once a pH of 7.0 was achieved in the 4-liter reaction
vessel, began addition of the remaining 5:1 Ca(OH).sub.2/CaCO.sub.3
slurry from the 20-liter agitated storage vessel, with a flow of
the 1.5 percent fiber mixture at 90 ml per minute, along with 48.5
ml per minute of additional water to the 4-liter agitated, double
jacketed reaction vessel while maintaining the flow of CO.sub.2 gas
(1.30 standard liter minute CO.sub.2/5.23 standard liter minute
air) at a rate to maintain conductivity level of approximately 90
percent ionic saturation, and maintain mass balance of the reaction
to maintain product concentration at approximately 4 percent to 5
percent solids. Continued addition of the material from the
agitated storage vessel to the reaction vessel until product
physical properties remained essentially unchanged. Addition of
material from the 20-liter storage vessel was stopped while
CO.sub.2 addition was continued until a pH of 7.0 was reached at
which time CO.sub.2 addition was stopped producing a 3.34:1
CaCO.sub.3/fiber composite with the PCC having a well defined
scalenohedral morphology.
[0058] The control fiber of the present invention was refined at
the Empire State Paper Research Institute (ESPRI) using an
Escher-Wyss (conical) refiner to an 80.degree. SR (freeness).
Measured by a fiber quality analyzer (using arithmatic means) the
control fiber measured 200-400 microns
[0059] How Control Filler-Fiber was Made
[0060] Produce a 15% solids slake and mix with fibers (.about.1.5%
consistency) React in the presence of CO.sub.2 to endpoint of pH of
7.0 producing a filler-fiber composite with a surface area of 6-11
m2/g (.about.60 to 80% PCC but can have more or less in
composite)
1TABLE 1 Breaking Length Physical Properties in Meters Filler
Loading Scalenohedral Aragonitic Rhombohedral Control Levels
Filler-fiber Filler-fiber Filler-fiber Filler-fiber 20 4,021 4,599
4,312 4,245 25 3,799 4,358 3,813 3,715 30 3,280 3,674 3,871
2,998
[0061]
2TABLE 2 Tensile Strength Physical Properties in kN/m Filler
Loading Scalenohedral Aragonitic Rhombohedral Control Levels
Filler-fiber Filler-fiber Filler-fiber Filler-fiber 20 3.062 3.555
3.397 3.382 25 3.124 3.324 2.999 3.021 30 2.658 2.785 3.005
2.448
[0062]
3TABLE 3 Internal Bond Strength Physical Properties in ft-lb Filler
Loading Scalenohedral Aragonitic Rhombohedral Control Levels
Filler-fiber Filler-fiber Filler-fiber Filler-fiber 20 237.70
264.07 283.13 255.67 25 263.20 285.95 251.65 256.95 30 242.63
248.60 273.65 249.53
[0063] The morphology controlled filler-fiber composite showed
equivalent or greater physical properties (i.e. tensil strength,
breaking length, and internal bond strength) as compared with the
control filler-fiber.
4TABLE 4 ISO Opacity Optical Properties Filler Loading
Scalenohedral Aragonitic Rhombohedral Control Levels Filler-fiber
Filler-fiber Filler-fiber Filler-fiber 20 89.20 88.20 87.38 88.18
25 89.93 89.15 88.78 89.55 30 90.95 90.40 89.68 90.83
[0064]
5TABLE 5 Pigment Scatter Optical Properties Filler Loading
Scalenohedral Aragonitic Rhombohedral Control Levels Filler-fiber
Filler-fiber Filler-fiber Filler-fiber 20 60.15 55.47 55.08 58.55
25 64.90 62.40 61.10 65.40 30 70.55 69.55 65.80 73.13
[0065] The morphology controlled filler-fiber composite showed
equivalent optical properties (i.e. ISO Opacity and Pigment
Scatter) as compared with the control filler-fiber.
* * * * *