U.S. patent application number 10/831526 was filed with the patent office on 2005-05-19 for paper and paper coating products produced using multi-phase calcium silicate hydrates.
Invention is credited to Mathur, Vijay K..
Application Number | 20050103459 10/831526 |
Document ID | / |
Family ID | 32109701 |
Filed Date | 2005-05-19 |
United States Patent
Application |
20050103459 |
Kind Code |
A1 |
Mathur, Vijay K. |
May 19, 2005 |
Paper and paper coating products produced using multi-phase calcium
silicate hydrates
Abstract
A paper composition including multiphasic calcium silicate
hydrate fillers. Multi-phase calcium silicate hydrates, having
unique physical and chemical properties, are prepared by
hydrothermal reaction of specified ratios of CaO and SiO2, normally
starting from slurries of slaked lime and from fluxed calcined
diatomaceous earth, each of which is at about the atmospheric
boiling point before being mixed and charged to a reactor, and
pressurized. The hydrothermal reaction is carried out while
maintaining the initial dilution for a preselected reaction time at
a preselected reaction temperature. The calcium silicate hydrates
have high water absorption and light scattering power, and have
optical and physical properties making them highly desirable as a
filler in papermaking.
Inventors: |
Mathur, Vijay K.; (Federal
Way, WA) |
Correspondence
Address: |
R REAMS GOODLOE, JR. & R. REAMS GOODLOE, P.S.
24722 104TH. AVENUE S.E.
SUITE 102
KENT
WA
98030-5322
US
|
Family ID: |
32109701 |
Appl. No.: |
10/831526 |
Filed: |
April 23, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10831526 |
Apr 23, 2004 |
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09649413 |
Aug 26, 2000 |
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6726807 |
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60150862 |
Aug 26, 1999 |
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Current U.S.
Class: |
162/181.6 ;
106/217.3; 106/286.6; 106/470 |
Current CPC
Class: |
D21H 21/285 20130101;
D21H 19/40 20130101; D21H 17/68 20130101; D21H 19/54 20130101 |
Class at
Publication: |
162/181.6 ;
106/217.3; 106/470; 106/286.6 |
International
Class: |
D21H 011/00 |
Claims
1. A paper composition, said composition comprising: an effective
amount of a filler, said filler comprising a multiple phase calcium
silicate hydrate comprising foshagite and xonotlite, and having
peaks in the XRD patterns from the foshagite and xenotlite
components in the complex having the characteristic XDR shown in
FIG. 1.
2. A paper composition according to claim 1, wherein said multiple
phase calcium silicate hydrate has a water absorption range of at
least about 500 percent.
3. A paper composition according to claim 1, wherein said multiple
phase calcium silicate hydrate has a water adsorption range of up
to approximately 1000 percent.
4. A highly absorbent coating formulation mixture for coating on a
printing paper substrate, said coating formulation mixture
comprising: an effective amount of a multiphasic calcium silicate
hydrate, said multiphasic calcium silicate hydrate comprising
foshagite and xonotlite having peaks in the XRD patterns from
foshagite and xenotlite components with the characteristic XDR
shown in FIG. 1. an aqueous starch solution; a dispersant; and a
binder.
5. A slurry of multiphasic calcium silicate hydrate, said slurry
comprising: fibrous primary crystals interlocked in secondary
particles of calcium silicate, said primary crystals and said
secondary particles having peaks in XRD patterns from the foshagite
and xenotlite components having the characteristic XDR shown in
FIG. 1; and wherein said interlocked fibrous primary crystals and
secondary particles are dispersed in water.
6. A slurry of multiphasic calcium silicate crystals as defined in
claim 5 in which contains the water is present in an amount of 80
percent or more by weight in said slurry.
7. A slurry of multiphasic calcium silicate crystals as defined in
claim 6 wherein at least about 95% of the secondary particles are
less than 40 microns in outside diameter.
8. A slurry of multiphasic calcium silicate crystals as defined in
claim 7 wherein at least about 80% of the secondary particles are
10 to 40 microns in outside diameter.
Description
RELATED PATENT APPLICATIONS
[0001] This application is a Divisional of co-pending allowed U.S.
application Ser. No. 09/649,413 filed Aug. 26, 2000, assigned U.S.
Pat. No. 6,726,807,to be issued on Apr. 27, 2004, which claimed
priority under 35 USC .sctn. 119 (e) from U.S. Provisional
Application Ser. No. 60/150,862 filed on Aug. 26, 1999, the
disclosures of each of which are incorporated herein by their
entirety by this reference.
COPYRIGHT RIGHTS IN THE DRAWING
[0002] A portion of the disclosure of this patent document contains
material that is subject to copyright protection. The applicant has
no objection to the facsimile reproduction by anyone of the patent
document or the patent disclosure, as it appears in the Patent and
Trademark Office patent file or records, but otherwise reserves all
copyright rights whatsoever.
TECHNICAL FIELD
[0003] This invention relates to novel paper products, paper
coatings, and pigment products, made using calcium silicate hydrate
("CSH") crystalline structures.
BACKGROUND
[0004] The paper industry currently utilizes many different types
of fillers as a substitute for pulp fiber, as well as to provide
desired functional and end-use properties to various paper and
paper products. For example, clay has long been used as a filler or
fiber substitute. Importantly, the use of clay also provides an
improvement in print quality. However, one disadvantage of clay is
that it is relatively low in brightness. And, the use of clay in
papermaking leads to a decrease in tensile strength of the paper
sheet, and to reductions in paper sheet caliper and stiffness.
[0005] Calcined clay was introduced to the paper industry in an
effort to improve brightness and opacity in paper. However, one
significant economic limitation of calcined clay is that it is
relatively expensive. Also, physically, calcined claim is highly
abrasive.
[0006] Titanium dioxide, TiO.sub.2, is another example of a filler
commonly used in papermaking. Most commonly, titanium dioxide is
used to improve opacity of the paper sheet, and, in some cases, it
is used to improve sheet brightness as well. Use of titanium
dioxide is limited, though, because it is extremely expensive.
Unfortunately, it is also the most abrasive pigment on the market
today. This is important because highly abrasive pigments are
detrimental in the paper industry since they wear down critical
paper machine components, such as forming wires, printing press
plates, and the like, ultimately leading to high life cycle costs
due to the constant repair and maintenance costs.
[0007] When calcined clay was first introduced, it was touted as a
titanium dioxide extender. Although it did succeed in extending
TiO.sub.2, it is nonetheless abrasive, and it is more expensive
than either standard clay or market pulp fiber.
[0008] More recently, and particularly since the mid 1980's, ground
calcium carbonate (GCC) has been used as a low cost alkaline
filler. Although GCC improved sheet brightness, one downside to GCC
was that it too is abrasive. Moreover, use of GCC reduces tensile
strength, caliper and stiffness of paper sheets. Consequently, a
paper sheet containing GCC tends to be rather limp.
[0009] Finally, one of the most commonly used alkaline paper
fillers is precipitated calcium carbonate(PCC). PCC is presently
one of the best compromise solutions for providing a high
brightness filler at an economically feasible price. However, a
significant downside to the use of PCC in paper sheets is that PCC
provides a lower light scattering power than either TiO.sub.2 or
calcined clay. Also, it often reduces sheet strength and
stiffness.
[0010] Thus, the paper industry still has an unmet need, and
continues to look for, a multi-functional pigment that can
simultaneously provide two or more of the following attributes:
[0011] a) cost that are less than TiO.sub.2;
[0012] b) better optical properties than calcined clay;
[0013] c) better optical properties than GCC;
[0014] d) better optical properties than PCC;
[0015] e) minimal tensile strength loss associated with increased
filler usage;
[0016] f) at least some improved strength characteristics, such as
sheet stiffness.
[0017] In addition to the just stated criteria, if a paper filler
could also simultaneously improve sheet porosity (i.e., provide a
more closed sheet) yet provide higher sheet caliper, it would be a
very highly desired filler material. To date, no single paper
filler with such attributes has been brought to the market.
Consequently, the development and commercial availability of such a
filler would be extremely desirable.
[0018] Finally, the current industry demand for printing papers,
especially the rapidly increasing demand for ink jet paper,
requires a high performance paper. The performance of such paper
would be enhanced by the availability of a pigment that would
provide excellent water and oil absorption capacities, so that the
paper could quickly capture and prevent ink from spreading or
bleeding, as well as aid in surface drying of the ink.
[0019] Some of the key requirements for an ideal papermaking
pigment can be summarized as set forth in Tables 1, 2 and 3
below:
1TABLE 1 Idealized Paper Filler Attributes Sheet Opacity Filler
Sheet Brightness Attribute Scattering Scattering Coefficient Power
Industry HIGHER HIGHER HIGHER EQUAL OR Requirement than pulp than
pulp than pulp HIGHER or or or than pulp carbonate carbonate
carbonate or fillers fillers fillers carbonate fillers
[0020]
2TABLE 2 Key strength parameters for an "Ideal" pigment. Sheet
Caliper Bulk Porosity Sheet Stiffness Tensile Attribute Smoothness
Industry HIGHER HIGHER HIGHER HIGHER HIGHER HIGHER Requirement than
than than than pulp than pulp than pulp pulp pulp pulp sheet sheet
sheet sheet sheet sheet alone or alone or alone or alone alone
alone with with with or with or with or with CaCO.sub.3 CaCO.sub.3
CaCO.sub.3 CaCO.sub.3 CaCO.sub.3 CaCO.sub.3 fillers fillers fillers
fillers fillers fillers
[0021]
3TABLE 3 Key printing requirements for an "Ideal" pigment. Sheet
Attribute Ink Penetration Show Through Print Through Industry LOWER
than LOWER than LOWER than Requirement pulp sheet alone pulp sheet
alone pulp sheet alone or with CaCO.sub.3 or with CaCO.sub.3 or
with CaCO.sub.3 filler filler filler
[0022] Currently, the papermaking industry uses various
combinations of available fillers in order to optimize the
properties as may be desired in a particular papermaking
application. However, because currently available fillers reduce
sheet strength to at least some extent, the industry relies on
strength additives, such as starch and/or polymers, to maintain the
desired paper strength properties when fillers are utilized.
Unfortunately, because different pigments have different particle
charge characteristics, additions of multiple pigments and
additives in the paper making system often create an extremely
complicated chemical system which may be somewhat sensitive and
difficult to control.
[0023] In summary, there remains a significant and as yet unmet
need for a high quality, cost effective filler which can be used to
simultaneously achieve desired optical properties and sheet
strength in paper products. Further, there remains a continuing,
unmet need for a method to reliably produce such a pigment which
has desirable optical properties and which provides significant
cost benefits when compared to the use of titanium dioxide or other
pigments currently utilized in the production of paper.
OBJECTS, ADVANTAGES AND NOVEL FEATURES
[0024] Accordingly, an important objective of my invention is to
provide a process for the manufacture of unique calcium silicate
hydrate ("CSH") products, which provide crystalline structures with
desired brightness, opacity, and other optical properties.
[0025] Another important and related objective is to provide an
economical substitute for current paper fillers such as titanium
dioxide.
[0026] A related and important objective is to provide a method for
the production of novel paper products using my unique calcium
silicate hydrate product.
[0027] An important objective is to provide a new calcium silicate
hydrate product with low bulk density, good chemical stability
(particularly in aqueous solutions), and a high adsorptive
capability, among other properties.
[0028] These and other advantages, and novel features of my
multi-phase calcium silicate hydrates, the method for their
preparation, and the improved pigments and paper products produced
therewith will become evident and more fully appreciated from full
evaluation and consideration of the following detailed description,
as well as the accompanying tables and drawing figures.
SUMMARY
[0029] I have now discovered the process conditions required to
reliably produce unique calcium silicate hydrate products with
particularly advantageous properties for use as a filler in
papermaking. The products are produced by reacting, under
hydrothermal conditions, a slurry of burned lime (quick lime) and a
slurry of fluxed calcined diatomaceous earth (or other appropriate
starting siliceous material). Preferably, a fine slurry of each of
the lime and the fluxed silica are utilized.
[0030] For one of my CSH products, the lime slurry is prepared by
providing about 1.54 pounds of suspended solids per gallon of lime
slurry. The silica slurry is prepared by providing about 1.55
pounds of suspended solids per gallon of water. The slaking of the
lime slurry raises the temperature of the slurry to near the
boiling point; this is accomplished before adding the same to the
fluxed silica. The slurry of fluxed calcined diatomaceous earth is
heated to near the boiling point, also, before it is mixed with the
lime slurry. When both slurries are near atmospheric boiling point
conditions, then they are mixed together and stirred, while being
retained under pressure in an autoclave or similar reactor.
Temperature of the reaction slurry is raised to between about
245.degree. C. and 260.degree. C., and the reaction is continued
for about two hours, more or less. The CaO/SiO2 ratio is
maintained, in the feed materials, of about 1.35 (.+-. about 0.10)
moles CaO to 1 mole of SiO2. After the reaction is completed, the
product is cooled before the pressure is released and the product
crystals are harvested.
[0031] Generally, the product of the above described reaction is a
multi-phase mixture (i.e., two different forms or phases are
present in the product), predominantly of foshagite, with some
xonotlite. Importantly, small, haystack like particles containing
complex multi-phase crystalline optical fibers are produced that
can be advantageously employed in papermaking for coating and for
wet end fillers. However, the hydrothermally produced multi-phase
crystalline optical fibers are vastly improved over previously
produced hydrothermal calcium silicate hydrates of which I am
aware, at least with respect to their physical properties, their
optical properties, and their utility as a filler in papermaking.
Moreover, my unique CSH products are suitable for multiple end
uses, such as filler for value added papers, for commodity papers,
for newsprint, paper coating applications, as well as for paints,
rubber compositions, and other structural materials.
[0032] It is important to appreciate that my hydrothermal process
for the manufacture of my unique multiple phase calcium silicate
hydrates ("CSH's"), including my novel multi-phase mixture of
foshagite and xonotlite, (CaO.sub.4(SiO.sub.3) (OH).sub.2 and
C.sub.6Si.sub.6O.sub.17(O- H).sub.2, respectively) results in a
unique mixture of calcium silicate hydrates which have a unique and
distinct X-ray diffraction pattern.
[0033] Further, the variables that affect the chemical composition
of my CSH products, and the primary and secondary structure of the
CSH particles and their characteristic properties, can be affected,
among other things, by (a) the CaO/SiO.sub.2 mole ratio, by (b)
concentration of the CaO and of the SiO.sub.2 in the reaction
slurry, (c) the reaction temperature, and (d) the reaction time. By
manipulating the just mentioned variables, I have been able to
develop two novel pigment products. Those two products can be
generally described as follows:
[0034] (1) A multi-phase calcium silicate hydrate having a primary
phase of foshagite, and a secondary phase of xonotlite. I refer to
this product as "TiSil" brand calcium silicate hydrate; and
[0035] (2) A multi-phase calcium silicate hydrate complex having a
primary phase fraction of riversideite with a minor phase fraction
of xonotlite. I refer to this product as "StiSil" brand calcium
silicate hydrate.
[0036] The first product is formed with a high CaO to SiO.sub.2
mole ratio (about a 1 to 1, to about a 1.7 to 1 ratio of CaO to
SiO2), at a high temperature (.about.200.degree. C.-300.degree.
C.), with a low final slurry concentration (.about.0.4-0.6 lb of
solids per gallon of slurry), and with a reaction time of
approximately 2 hours. It has a characteristic X-ray diffraction
pattern as shown in FIG. 1. The scanning electron micrographs
("SEMs") of this product are shown in FIGS. 2 and 3. As is evident
from the SEMs, this product consists of primary, fibrous particles
joined together, and thus, produces a secondary, three dimensional,
"hay-stack" structure. The physio-chemical characteristics of this
product are unique. For example, extremely high water absorption is
provided. This pigment also provides unique paper properties when
utilized in papermaking. For example, this pigment, when used as a
filler, can improve the optical properties along with sheet
strength, sheet bulk, sheet smoothness, and sheet porosity,
simultaneously.
[0037] The second product is formed by reacting lime and silica
with a low mole-ratio (about a 0.85 to 1 ratio of CaO to SiO2), a
low reaction temperature (.about.180.degree. C. to 190.degree. C.),
at a high final slurry concentration (.about.0.7-1.0 pounds of
solids per gallon of slurry), and with a reaction time of
approximately 2 hours. This calcium silicate is quite different
from the first product just mentioned above and its unique X-ray
diffraction pattern is given in FIG. 4. The scanning electron
micrographs (SEMs) for this product are given in FIGS. 5 and 6. As
the SEMs indicate, this product consists of some fibrous growths
that in turn grow randomly and almost continuously to provide an
irregular globular structure. This product is uniquely formulated
to provide ultra high sheet stiffness when it is used as a filler
in paper.
[0038] In summary, the unique features of these hydrothermally
produced calcium silicate hydrate products include:
[0039] a unique crystallo-chemical composition
[0040] a multi-phase crystal system
[0041] a primary and secondary fibrous particle structure
[0042] a high water absorptivity (in the .about.300%-1000%
range).
[0043] The result of the unique properties and physical structure
enable these unique CSH products to provide a combination of
beneficial properties to paper products in a manner heretofore
unknown by paper fillers. For example, the use of these products in
paper can increase sheet bulk and Gurley porosity, simultaneously.
In addition, these products are made up of large particles, but the
products can still scatter light better than PCC, GCC, clay, or
even calcined clay.
BRIEF DESCRIPTION OF THE DRAWING
[0044] The patent or application file contains at least one black
and white photograph as a drawing. Copies of this patent or patent
application publication with black and white drawing(s) will be
provided by the U.S. Patent and Trademark Office upon request and
payment of the necessary fee.
[0045] In order to enable the reader to attain a more complete
appreciation of the invention, and of the novel features and the
advantages thereof, attention is directed to the following detailed
description when considered in connection with the accompanying
drawing, wherein:
[0046] FIG. 1 illustrates the characteristic X-ray diffraction
pattern of one embodiment of the present invention, where foshagite
and xonotlite are present.
[0047] FIG. 2 is a scanning electron micrograph ("SEM") (at
10,000.times.magnification) of the product described by the X-ray
diffraction pattern just set forth in FIG. 1, showing in detail the
primary, fibrous particles which are joined together.
[0048] FIG. 3 is a scanning electron micrograph ("SEM") (at
2000.times.magnification) of the product described by the X-ray
diffraction pattern just set forth in FIG. 1 and also just
illustrated in FIG. 2, now showing how the primary, fibrous
particles are joined together, producing a secondary, three
dimensional, "hay-stack" structure.
[0049] FIG. 4 illustrates the characteristic X-ray diffraction
pattern of another embodiment of the present invention, where
riversideite and xonotlite are present.
[0050] FIG. 5 is a scanning electron micrograph ("SEM") (at
10,000.times.magnification) of the product described by the X-ray
diffraction pattern just set forth in FIG. 4, showing in detail the
globular particles which are provided.
[0051] FIG. 6 is a scanning electron micrograph ("SEM") (at
2000.times.magnification) of the product described by the X-ray
diffraction pattern just set forth in FIG. 4 and also just
illustrated in FIG. 5, now showing details of several
particles.
[0052] FIG. 7 illustrates the solubility of lime in water as a
function of temperature.
[0053] FIG. 8 illustrates the solubility of various forms of silica
in water as a function of temperature.
[0054] FIG. 9 illustrates one heating and cooling cycle which has
been found to be advantageous for reaction conditions suitable for
formation of the "TISIL.TM." brand product described in FIGS. 1, 2,
and 3 above.
[0055] FIG. 10 is a comparison of sheet brightness as a function of
percent filler, when using as filler either a commercial
precipitated calcium carbonate (PCC) or the novel calcium silicate
hydrate ("TISIL.TM." brand) product described herein.
[0056] FIG. 11 is a comparison of sheet opacity results as a
function of percent filler when using as filler either a commercial
precipitated calcium carbonate (PCC) or the novel calcium silicate
hydrate ("TISIL.TM." brand) product described herein.
[0057] FIG. 12 is a comparison of sheet scattering coefficient
results as a function of percent filler when using as filler either
a commercial precipitated calcium carbonate (PCC) or the novel
calcium silicate hydrate ("TISIL.TM." brand) product described
herein.
[0058] FIG. 13 is a comparison of filler scattering coefficient
results as a function of percent filler between commercial
precipitated calcium carbonate (PCC) and the novel calcium silicate
hydrate ("TISIL.TM." brand) product described herein.
[0059] FIG. 14 provides a comparison of paper sheet stiffness as a
function of percent filler, between a commercial precipitated
calcium carbonate (PCC) and the novel calcium silicate hydrate
("TISIL.TM. " brand) product described herein.
[0060] FIG. 15 provides a comparison of paper sheet bulk as a
function of percent filler, between a commercial precipitated
calcium carbonate (PCC) and the novel calcium silicate hydrate
("TISIL.TM." brand) product described herein.
[0061] FIG. 16 provides a comparison of paper sheet porosity as a
function of percent filler, between a commercial precipitated
calcium carbonate (PCC) and the novel calcium silicate hydrate
("TISIL.TM." brand) product described herein.
[0062] FIG. 17 provides a comparison of paper sheet tensile index
as a function of percent filler, between a commercial precipitated
calcium carbonate (PCC) and the novel calcium silicate hydrate
("TISIL.TM." brand) product described herein.
[0063] FIG. 18 provides a comparison of paper sheet brightness as a
function of percent filler, between (a) the combination of a
commercial precipitated calcium carbonate (PCC) and titanium
dioxide, and (b) the novel calcium silicate hydrate ("TISIL.TM."
brand) product described herein.
[0064] FIG. 19 provides a comparison of paper sheet opacity as a
function of percent filler, between (a) the combination of a
commercial precipitated calcium carbonate (PCC) and titanium
dioxide, and (b) the novel calcium silicate hydrate ("TISIL.TM."
brand) product described herein.
[0065] FIG. 20 provides a comparison of paper sheet scattering
coefficient as a function of percent filler, between (a) the
combination of a commercial precipitated calcium carbonate (PCC)
and titanium dioxide, and (b) the novel calcium silicate hydrate
("TISIL.TM." brand) product described herein.
[0066] FIG. 21 provides a comparison of filler scattering
coefficient, between (a) the combination of a commercial
precipitated calcium carbonate (PCC) and titanium dioxide, and (b)
the novel calcium silicate hydrate ("TISIL.TM." brand) product
described herein.
[0067] FIG. 22 provides a comparison of paper sheet stiffness as a
function of percent filler, between (a) the combination of a
commercial precipitated calcium carbonate (PCC) and titanium
dioxide, and (b) the novel calcium silicate hydrate ("TISIL.TM."
brand) product described herein.
[0068] FIG. 23 provides a comparison of paper sheet bulk as a
function of percent filler, between (a) the combination of a
commercial precipitated calcium carbonate (PCC) and titanium
dioxide, and (b) the novel calcium silicate hydrate ("TISIL.TM."
brand) product described herein.
[0069] FIG. 24 provides a comparison of paper sheet porosity as a
function of percent filler, between (a) the combination of a
commercial precipitated calcium carbonate (PCC) and titanium
dioxide, and (b) the novel calcium silicate hydrate ("TISIL.TM."
brand) product described herein.
[0070] FIG. 25 provides a comparison of paper sheet tensile index
as a function of percent filler, between (a) the combination of a
commercial precipitated calcium carbonate (PCC) and titanium
dioxide, and (b) the novel calcium silicate hydrate ("TISIL.TM."
brand) product described herein.
[0071] FIG. 26 provides a comparison of paper sheet opacity as a
function of ash level, between (a) a commercial calcium silicate
("BULKITE.TM." brand) and (b) the novel calcium silicate hydrate
("TISIL.TM." brand) product described herein.
[0072] FIG. 27 provides a comparison of paper sheet scattering
coefficient as a function of ash level, between (a) a commercial
calcium silicate ("BULKITE.TM." brand) and (b) the novel calcium
silicate hydrate ("TISIL.TM." brand) product described herein.
[0073] FIG. 28 provides a comparison of filler scattering
coefficient as a function of ash level between (a) a commercial
calcium silicate ("BULKITE.TM." brand) and (b) the novel calcium
silicate hydrate ("TISIL.TM." brand) product described herein.
[0074] FIG. 29 a comparison of paper sheet brightness as a function
of ash level, between (a) a commercial calcium silicate
("BULKITE.TM." brand) and (b) the novel calcium silicate hydrate
("TISIL.TM." brand) product described herein.
[0075] FIG. 30 provides a comparison of paper sheet porosity as a
function of ash level, between (a) a commercial calcium silicate
("BULKITE.TM." brand) and (b) the novel calcium silicate hydrate
("TISIL.TM." brand) product described herein.
[0076] FIG. 31 provides a comparison of the normalized paper sheet
opacity (interpolated to six (6) percent ash), when using various
fillers, namely (a) a commercial calcium silicate ("HUBERSIL.RTM."
brand), or (b) a commercial calcium carbonate ("HUBER.RTM.
Carbonate" brand), or (c) the novel calcium silicate hydrate
("TISIL.TM." brand) product described herein.
[0077] FIG. 32 provides a comparison of the sheet ink penetration
results on newsprint sheets containing various fillers,
interpolated to six (6) percent ash, showing the ink penetration
when the newsprint was manufactured using (a) a commercial calcium
silicate ("HUBERSIL.RTM." brand), (b) a commercial calcium
carbonate ("HUBER.RTM. Carbonate" brand) , or (c) the novel calcium
silicate hydrate ("TISIL.TM." brand) product described herein.
[0078] FIG. 33 provides a comparison of the paper sheet show
through results on newsprint sheets containing various fillers,
interpolated to six (6) percent ash, showing the sheet show through
results when the newsprint was manufactured using (a) a commercial
calcium silicate ("HUBERSIL.RTM." brand) , (b) a commercial calcium
carbonate ("HUBER.RTM. Carbonate"), or (c) the novel calcium
silicate hydrate ("TISIL.TM." brand) product described herein.
[0079] FIG. 34 provides a comparison of the paper sheet print
through results on newsprint sheets containing various fillers,
interpolated to six (6) percent ash, showing the sheet print
through results when the newsprint was manufactured using (a) a
commercial calcium silicate ("HUBERSIL.RTM." brand), (b) a
commercial calcium carbonate ("HUBER.RTM. Carbonate" brand), or (c)
the novel calcium silicate hydrate ("TISIL.TM." brand) product
described herein.
[0080] FIG. 35 provides a comparison of the Gurley sheet porosity
results on newsprint sheets containing various fillers,
interpolated to six (6) percent ash, showing the sheet porosity
when the newsprint was manufactured using (a) a commercial calcium
silicate ("HUBERSIL.RTM." brand), (b) a commercial calcium
carbonate ("HUBER.RTM. Carbonate" brand), or (c) the novel calcium
silicate hydrate ("TISIL.TM." brand) product described herein.
[0081] FIG. 36 provides a comparison of the sheet tensile index
results on newsprint sheets containing various fillers,
interpolated to six (6) percent ash, showing the sheet tensile
index results when the newsprint was manufactured using (a) a
commercial calcium silicate ("HUBERSIL.RTM." brand), (b) a
commercial calcium carbonate ("HUBER.RTM. Carbonate" brand), or (c)
the novel calcium silicate hydrate ("TISIL.TM." brand) product
described herein.
[0082] FIG. 37 provides a comparison of the Gurley sheet stiffness
results on newsprint sheets containing various fillers,
interpolated to six (6) percent ash, showing the sheet stiffness
when the newsprint was manufactured using (a) a commercial calcium
silicate ("HUBERSIL.RTM." brand) , (b) a commercial calcium
carbonate ("HUBER.RTM. Carbonate" brand), or (c) the novel calcium
silicate hydrate ("TISIL.TM." brand) product described herein.
[0083] FIG. 38 provides a comparison of the sheet static
coefficient of friction results on newsprint sheets containing
various fillers, interpolated to six (6) percent ash, showing the
sheet static coefficient of friction when the newsprint was
manufactured using (a) a commercial calcium silicate
("HUBERSIL.RTM." brand), (b) a commercial calcium carbonate
("HUBER.RTM. Carbonate" brand), or (c) the novel calcium silicate
hydrate ("TISIL.TM." brand) product described herein.
[0084] FIG. 39 provides a comparison of the Sheffield sheet
smoothness results on newsprint sheets containing various fillers,
interpolated to six (6) percent ash, showing the sheet Sheffield
sheet smoothness when the newsprint was manufactured using (a) a
commercial calcium silicate ("HUBERSIL.RTM." brand), (b) a
commercial calcium carbonate ("HUBER.RTM. Carbonate" brand), or (c)
the novel calcium silicate hydrate ("TISI.TM." brand) product
described herein.
[0085] The foregoing figures, being merely exemplary, contain
various aspects, properties, and elements that may be present or
omitted from actual product implementations depending upon the
circumstances. An attempt has been made to provide the figures in a
way that illustrates at least those aspects and properties that are
significant for an understanding of the various embodiments and
aspects of the invention. However, variations in the illustrated
aspects, elements, and properties, especially as applied for
maximizing different variations of the functional properties
illustrated, may be utilized in various embodiments in order to
provide an advantageous calcium silicate hydrate filler for various
uses in the manufacture of paper.
DETAILED DESCRIPTION
[0086] In order to prepare my unique calcium silicate hydrates
("CSH") products, it is first necessary to prepare a source of
calcium. This is normally accomplished by the formation of a slurry
of calcious material, most commonly lime. However, there are
several different sources of calcium, which may be used. Some
examples are CaCO.sub.3, CaCl.sub.2, and hydrated lime. I have
found it advantageous to employ pebble lime, if less than 1/2 inch
dimension. First, the CaO was slaked in water. The amount and the
rate of addition of lime were set and maintained in order to obtain
a desired concentration of lime slurry. Because the slaking of lime
is an exothermic process, it was necessary to control both the rate
of addition of lime and the quantity of water used. When slaking,
the best temperature was determined to be near boiling, i.e., close
to 100.degree. C. (212.degree. F.) in order to form lime particles
as fine as possible. Once the slaking was complete, the lime slurry
was then screened through a 200 mesh screen to remove any grit and
oversized particles. The screened and slaked lime slurry was tested
for available lime (as CaO) and then transferred to an
autoclave.
[0087] The chemistry of the slaking process can be given as
follows:
CaO+H.sub.2O.fwdarw.Ca(OH).sub.2 (1)
[0088] (solid) (aqueous)
Ca(OH).fwdarw.Ca.sup.+++2OH.sup.- (2)
[0089] (aqueous)
[0090] The solubility of calcium hydroxide slurry is inversely
proportional to the temperature, as indicated in FIG. 7.
[0091] Next, it is necessary to prepare a slurry of siliceous
material (i.e., a SiO2 slurry). Various siliceous materials such as
quartz, water glass, clay, pure silica, natural silica (sand),
diatomaceous earth, fluxed calcined diatomaceous earth, or any
combination thereof may be utilized as a source of siliceous
material. I prefer to utilize an ultra fine grade of fluxed,
calcined diatomaceous earth. This raw material was prepared into a
slurry of .about.1.55 lbs of solids per gallon water. The slurry
was then preheated to near boiling, i.e., near 100.degree. C.
[0092] Importantly, the solubility of silica (unlike that of
Ca(OH).sub.2), is directly proportional to temperature, as seen in
FIG. 8. For example, quartz (line A in FIG. 8) is only slightly
soluble up to 100.degree. C. From 100.degree. C. to 130.degree. C.,
it starts solubilizing and around 270.degree. C., it reaches its
maximum solubility of about 0.07%.
[0093] The dissolution of silica can be represented as follows:
(SiO.sub.2).sub.n+2n(H.sub.2O).fwdarw.nSi(OH).sub.4 (3)
[0094] The solubility of silica can be increased by raising the pH,
and/or by using various additives (i.e. sodium hydroxide). In
addition the rate of silica solubility is also a function of
particle size, thus to enhance solubilization of the silica, I
prefer to utilize ultra fine fluxed calcined diatomaceous
earth.
[0095] Next, the siliceous slurry was mixed with the lime slurry in
an autoclave, to achieve a hydrothermal reaction of the two
slurries. Important, the amount of CaO in the lime slurry and the
amount of SiO.sub.2 in the fluxed calcined diatomaceous earth
slurry were pre-selected to provide a predetermined CaO/SiO.sub.2
mole ratio. Also, the concentration of the two slurries (CaO and
SiO.sub.2) was selected so that the final concentration of the
reaction mixture in the autoclave falls between about 0.2 pounds of
solid per gallon of slurry to about 1.0 pounds of solid per gallon
of slurry.
[0096] The hydrothermal reaction itself was carried out in a
pressurized vessel, with three major steps:
[0097] (1) Heating the slurry to the desired temperature (e.g.
180.degree. C. to 300.degree. C.)
[0098] (2) Reacting at temperature for a specified time (e.g. 60
minutes to 240 minutes).
[0099] (3) Stopping the reaction and cooling down
[0100] In my laboratory, the reaction autoclave was cooled by
passing quenching water through an internal cooling coil, or by
utilizing an external jacketed cooling system. I prefer to utilize
a cool down process of from approximately 25 to 30 minutes to drop
the temperature from about 230.degree. C. to about 80.degree. C.,
as indicated in FIG. 9.
[0101] The process steps just mentioned are very important. This is
because I have utilized the inverse solubilities of lime and silica
with respect to temperature and time in an effort to produce the
desired reaction composition, to arrive at the desired multi-phase
calcium silicate hydrate product.
[0102] Without limiting my invention to any particular theory, I
can postulate the following reaction during the hydro-thermal
reaction between calcious material and siliceous material. First,
during the heating process, very few free Ca.sup.++ ions are
available. After 100.degree. C., the silica starts going into a gel
stage. Beyond 130.degree. C., the silica ions become available for
reacting. As the temperature nears 180.degree. C., the calcium ion
Ca.sup.++ reacts with the Si.sup.+ ion to form a metal silicate.
The reaction can be written as follows:
x[Ca.sup.+++2OH.sup.-]+y[Si(OH).sub.4].fwdarw.CaO.sub.x(SiO.sub.2).sub.y+(-
x+y)H.sub.2O (4)
[0103] Where:
[0104] x=1 to 6
[0105] y=1 to 6
[0106] The solid Ca(OH).sub.2 particles react with SiO.sub.2 in the
gel phase to give a calcium silicate hydroxide whose
crystallo-chemical structure can be written as
Ca.sub.6Si.sub.6O.sub.17(OH).sub.2 (Xonotlite). As the temperature
is further raised from 180.degree. C. to 250.degree. C., calcium
silicate hydride condenses with the remaining Ca(OH).sub.2
particles to give yet another calcium silicate hydroxide, this time
with a distinct X-ray diffraction pattern and a crystallo-chemical
formula of CaO.sub.4(SiO.sub.3).sub.3(OH).sub.2 (Foshagite)
[0107] Further, I have developed my hydrothermal reaction process
so that more than one unique calcium silicate hydrate can be
produced. In this respect, it is important to note that the
following variables are critical in producing a desired end
product:
[0108] 1) Slaking Temperature
[0109] 2) CaO/SiO.sub.2 mole ratio
[0110] 3) Slurry Concentration
[0111] 4) Reaction Temperature
[0112] 5) Reaction Time at Temperature
[0113] By changing these variables, a product having several
different phases of calcium silicate hydroxide can be produced.
Some of these phases may include:
4 Morphol- X-ray Diffraction peaks Formula ogy Major Minor
Ca.sub.4(SiO.sub.3).sub.3(OH).sub.2 Foshagite d = 2.93 .ANG., d =
2.16 .ANG., d = 4.96 .ANG. Ca.sub.6Si.sub.6O.sub.17 Xonotlite d =
3.02 .ANG., d = 2.04 .ANG., d = 8.50 .ANG.
Ca.sub.5Si.sub.6O.sub.17(OH).sub.2 River- d = 3.055 .ANG., d = 3.58
.ANG., d = 2.80 .ANG. sideite
[0114] Although not normally important, one should note that my
final product CSH composition may also contain minor amounts of
calcite-aragonite, produced as a result of side reactions.
[0115] The first and most important product of my process is a
multi-phase CSH composition having various amounts of phases of
matter represented by CaO.sub.4 (SiO.sub.3).sub.3 (OH).sub.2
(Foshagite) and Ca.sub.6Si.sub.6O.sub.17(OH).sub.2 (Xonotlite). A
unique X-ray diffraction pattern for this product is provided in
FIG. 1. In that XRD, the crystallochemical formula of the mixture,
and the characteristic d spacings, are given below:
Foshagite, CaO.sub.4 (SiO.sub.3).sub.3 (OH).sub.2 d=2.97 .ANG.,
d=2.31 .ANG., d=5.05 .ANG. (Phase I)
Xonotlite, Ca.sub.6Si.sub.6O.sub.17(OH).sub.2 d=3.107 .ANG., d=1.75
.ANG., d=3.66 .ANG. (Phase II)
[0116] The Scanning Electron Micrographs ("SEMs") representing this
first product are provided in FIGS. 2 and 3. As shown in FIGS. 2
and 3, it is important to note that the product consists of primary
particles and secondary particles. The primary particles have a
diameter between 0.1 and 0.2 microns and a length between 1.0 and
4.0 microns. FIG. 3 also indicates that the primary particle has
two phases. The rod or ribbon like structure is characteristic of
xonotlite (Ca.sub.6Si.sub.6O.sub.17(O- H.sub.2)) while the
predominant structures are thin and fibrous, characteristic of
foshagite (Ca.sub.4(SiO.sub.3).sub.3(OH) .sub.2). The diameter of
the foshagite crystals ranges from 0.1 to 0.3 microns and the
length is ranges from 2.0 to 5.0 microns.
[0117] The SEM of FIG. 3 reveals a secondary, three dimensional
structure. This three dimensional structure is believed to be
formed by the interlocking of the fibrous material and the
continuous growth of the "gel" like material at the intersection of
the individual particles. This may also be the reason that the
secondary structure is fairly stable. Importantly, the secondary
structure can generally withstand the shear forces encountered
during the discharge of material from pressure vessels after the
reaction has completed, as well as shear forces encountered during
papermaking. This is seen, for example, in that the secondary
structure maintains its "bulk density" during some of the end use
processes such as calendering during paper making. The particle
size of secondary structure, as measured by particle size measuring
devices like the Malvern Mastersizer, is in the range of 10-40
microns.
[0118] The calcium silicate hydroxide mixture of my invention also
has very high brightness characteristics. A comparison with other
pigments is given below:
[0119] Various pigments and their typical published brightness
values are as follows:
5 Pigment GE (TAPPI) Brightness (%) Calcium Silicate Hydrate 95-97
(TiSil Brand CSH) Calcined (High Brightness) 89-91 Clay Filler Clay
85-88 Synthetic Silica 97-100 Calcium Carbonate 95 .+-. 1
[0120] One of the most significant characteristics of the
composition of matter produced by my process is the ability of
these multiple phase calcium silicates to absorb large amounts of
water. These calcium silicates can adsorb anywhere from 350% to
1000% of their weight. This high water absorption capacity makes my
pigment extremely well suited for preventing ink strike through in
writing and printing papers, newsprint and more.
EXAMPLE 1
Manufacture of Multiple Phase Silicate Hydrates (5XPC 12)
[0121] Initially, 135.09 grams of 1/2" rotary pebble lime
(Mississippi Lime Co.) was accurately weighed and slaked in 410
milliliters of de-ionized water. The slaking reaction is exothermic
and caused the slurry temperature to rise to near boiling. When the
slurry temperature was very near boiling and before much of the
water had evaporated, an additional 1190 milliliters of water was
added to both dilute and cool the slurry. The slurry was then
agitated for 30 minutes to insure slaking completion before being
screened through a 140 mesh screen. The slurry was then transferred
to 5 liter autoclave and tested for lime availability in accordance
with ASTM method C25. The autoclave is fitted with an outside
heating element contained in an insulated jacket housing. The
autoclave is also fitted with a variable speed magnetic drive for
stirring the slurry during reaction. Approximately 109.6 grams of
ultra fine fluxed calcined diatomaceous earth was weighed and added
to 750 ml of hot water (concentration of .about.1.22 lb/gallon).
The silica slurry was heated for approximately 10 minutes, to near
boiling, then added to the screened and tested lime slurry. The
exact amount of silica slurry added to lime slurry was determined
by the lime availability such that a mol ratio of 1.35 mol
CaO/SiO.sub.2 would be maintained. The total slurry volume was also
adjusted to a final concentration of 0.425 lb/gallon. The high
pressure vessel was then closed, sealed, and connected to an
automated heating/cooling control system (RX 330). The contents of
the autoclave were under constant agitation via the magnetic drive
motor mentioned above.
[0122] The high pressure reactor was heated by an externally
jacketed heating element. The autoclave was continuously agitated
at a constant speed of 338 rpm. The reactor was heated for
approximately 100 minutes in order to reach the target temperature
of 245.degree. C. (473.degree. F.). The temperature was maintained
at 245.degree. C. for 2 hours, after heating to the target
temperature was accomplished, with the use of the heating/cooling
controller. At the end of the reaction, the "quenching" water was
flushed through the cooling coil built inside the autoclave. This
cooling process was maintained until the inside vessel temperature
reached approximately 80.degree. C. (approximately 30 minutes). At
which point, the vessel was opened and the reaction products were
transferred to a holding vessel for storage. A portion of the
resultant slurry was dried in a 105.degree. C. oven for 12 hours.
During the drying process, the slurry formed hard lumps, which had
to be broken up through the use of a mortar and pestle. The now
powdered, dry product was brushed through a 140 mesh screen to
insure product uniformity when testing. The pigment in this example
was designated 5XPC 12. The test carried out on the dry powder were
as follows:
[0123] 1) X-ray diffraction analysis
[0124] 2) Scanning Electron Micrograph (S.E.M.)
[0125] 3) Brightness
[0126] 4) Percent Water Absorption
[0127] 5) Air Permeability (Blaine Method)
[0128] 6) pH
[0129] For the air permeability test, two numbers are reported. The
first is the weight in grams of powder required to fill the capsule
and is an indication of the "bulk density" of the powder. The
second is the time in seconds for a controlled volume of air to
pass through the compressed powder inside the capsule and is an
approximate measure of the "structure" of the particle.
[0130] The process conditions are given in Table 1a and the pigment
properties are given in Table 1b.
6TABLE 1a Process conditions of 5XPC 12 Concen- Average Reaction
Mol Ratio tration Temperature Pressure Time Batch # (CaO/SiO.sub.2)
(lb/gallon) (.degree. C.) (psi) (hours) 5XPC 12 1.35 0.425 245 456
2.0
[0131]
7TABLE 1b Pigment Properties of 5XPC 12 Air Air Water Permeability
Permeability GE Brightness Absorption Blaine Wt. Blaine time Batch
# (% reflectance) (%) (g) (sec.) 5XPC 12 96.4 880 0.35 81.8
[0132] The x-ray diffraction pattern of this novel, multiphase
calcium silicate hydrate is given in FIG. 1. This product
(identified as 5XPC 12) gave a unique x-ray pattern. The pattern
indicated that the powder had one major phase and one minor phase.
The summary of the characteristic "peaks" is shown in Table 1c.
[0133] The major peaks for phase I were found to indicate the
presence of calcium silicate
hydroxide--Foshagite--(Ca.sub.4(SiO.sub.3).sub.3(OH).sub- .2) with
major peaks at d(.ANG.)=2.97, d(.ANG.)=2.31 and a minor peak at
d(.ANG.)=5.05. For phase II, the x-ray diffraction pattern
indicated the presence of calcium silicate
hydrate--Xonotlite--(Ca.sub.6Si.sub.6O.sub.1- 7(OH).sub.2) with
major peaks at d(.ANG.)=3.107, d(.ANG.)=1.75 and a minor peak at
d(.ANG.)=3.66. Thus I obtained a novel combination of Foshagite and
Xonotlite from a single reaction.
8TABLE 1c X-ray diffraction peak summary for 5XPC 12
Crystallochemical d-spacing d-spacing d-spacing Common Name Formula
(Major) (median) (Minor) Foshagite
CaO.sub.4(SiO.sub.3).sub.3(OH).sub.2 d = d = d = (Phase I) (Major)
2.97 .ANG. 2.31 .ANG. 5.05 .ANG. Xonotlite Ca.sub.6Si.sub.6O.sub.1-
7(OH).sub.2 d = d = D = (Phase II) (Minor) 3.107 .ANG. 1.75 .ANG.
3.66 .ANG.
[0134] The S.E.M. pictures at 10,000 times and 2000 times
magnification are given in FIGS. 2 and 3, respectively. The high
magnification S.E.M. clearly shows the fibrous structure of
Foshagite and a small fraction of "rod" or "ribbon" like, tubular
structures of Xonotlite. The diameter of the Foshagite "fibers"
ranges from 0.1 to 0.2 microns while the length ranges from 1 to 5
microns. The Xonotlite particles had diameters in the range of 0.1
to 0.3 microns and a length in the range of 1 to 3 microns.
[0135] The low magnification S.E.M. depicts the three dimensional
structure of the secondary particles of calcium silicate hydrates.
The structure appears to have been formed by an interlocking of the
primary "fibrous" crystals and some inter-fiber bonding due to
hydrogel of silica formed during the initial stages of
hydro-thermal reaction. Because of these two main reasons, the
secondary particles are fairly stable and do not significantly lose
their 3-d structure when subjected to process shear. In addition,
these particles also seem to withstand the pressure encountered
during the calendering or finishing operations integral to
papermaking. The median size of the secondary particles as seen,
ranges from 10 to about 40 microns.
[0136] In order to evaluate this pigment in paper, handsheets were
prepared for evaluation. Handsheets were prepared using the 5XPC 12
product sample in order to evaluate the papermaking characteristics
of the pigment. The procedure included preparation of a standard
pulp slurry made up of 75% hardwood and 25% softwood. Both pulp
sources were beaten separately, in a Valley Beater, to a specific
Canadian Standard Freeness of 450.+-.10 in accordance with TAPPI
test methods T-200 and T-227. Handsheets were formed from the
prepared stock, on a 6" British handsheet mold, in accordance with
TAPPI test method T-205. The exceptions to the standard method were
as follows. Since the goal of producing these handsheets was to
test filler performance, some filler was incorporated into the
handsheets at various replacement levels (usually 15%, 20%, and
25%). In order to achieve comparability between different levels, a
constant basis weight was achieved via a reduction in fiber
content. Thus, a 25% filled sheet would contain only 75% of the
fiber that the unfilled sheet had. The next variation on the
standard test method was the addition of retention aid. A retention
aid (Percol 175) was added to hold the filler in the sheet until
the sheet had dried completely. All other handsheet formation
components were kept consistent with TAPPI test method T-205.
[0137] The handsheets were tested in accordance with TAPPI test
method T-220, with one exception. Instead of using a 15 mm sample
for testing tensile, a 25.4 mm sample was used and the tensile
index calculations were altered accordingly. The handsheets were
ashed in accordance with TAPPI test method T-211.
[0138] Paper handsheets were tested for the following
properties:
[0139] 1. Opacity
[0140] 2. Sheet Scattering Coefficient
[0141] 3. Filler Scattering Coefficient
[0142] 4. Brightness
[0143] 5. Sheet Bulk (Basis Weight/Caliper ratio)
[0144] 6. Sheet Stiffness
[0145] 7. Sheet Porosity
[0146] 8. Sheet Smoothness
[0147] 9. Sheet Tensile Index
[0148] A standard alkaline filler, precipitated calcium carbonate
(SMI Albacar HO), was used as a reference material to gauge product
performance. The results of the handsheet evaluation are given in
Tables 1d and 1e.
9TABLE 1d Optical property performance of handsheets containing 20%
(interpolated) 5XPC 12 and pulp only. Sheet Filler Scattering
Scattering Brightness Coefficient Coefficient Pigment (ISO) Opacity
(ISO) (cm.sup.2/g) (cm.sup.2/g) 5XPC 12 90.56 90.88 835.21 3077.24
Pulp Only 85.73 73.19 274.8 NM Improvement +5.6% +24.2% +203.9% --
over pulp
[0149]
10TABLE 1e Strength property performance of handsheets containing
20% (interpolated) 5XPC 12 and pulp only. Stiffness Porosity
(Gurley (sec/100 cc Pigment Units) Bulk (cm.sup.3/g) air) 5XPC 12
150.74 1.73 64.91 Pulp Only 137.15 1.40 51.94 Improvement +9.9%
+23.3% +25.0% over pulp
[0150]
11TABLE 1f Optical property performance of handsheets containing
20% (interpolated) 5XPC 12 and 20% (interpolated) PCC. Sheet Filler
Scattering Scattering Brightness Opacity Coefficient Coefficient
Pigment (ISO) (ISO) (cm.sup.2/g) (cm.sup.2/g) 5XPC 12 90.56 90.88
835.12 3077.24 PCC 90.44 88.69 709.84 2474.48 Improvement Even
+2.47% +17.66% +24.36% over PCC
[0151]
12TABLE 1g Strength property performance of handsheets containing
20% (interpolated) of 5XPC 12 and 20% (interpolated) PCC. Porosity
Stiffness Tensile Bulk (sec/100 cc (Gurley Index Pigment
(cm.sup.3/g) air) Units) (Nm/g) 5XPC 12 1.73 64.91 150.74 31.17 PCC
1.55 22.24 107.54 27.95 Improvement +11.56% +191.9% +40.17% +11.53%
over PCC
EXAMPLE 2
(5XPC--27 pigment sample)
[0152] This novel, multiphase calcium silicate hydrate was formed
by hydro-thermal reaction of lime and silica. The CaO/SiO.sub.2 mol
ratio used for this new product was 0.85, the final slurry
concentration was .about.0.8 lb/gallon, the reaction temperature
was 190.degree. C., and the reaction time was 2.5 hours. A summary
of these conditions is given in Table 2a.
[0153] A totally new product was formed using a new set of reaction
conditions. First, the CaO/SiO.sub.2 mol ratio was adjusted to
0.85, the reaction temperature was set to 190.degree. C., the
slurry concentration was increased to 0.75 lbs/gallon, and the
reaction time was increased to 2.5 hours. The product of this
example was designated 5XPC 27.
[0154] A summary of the reaction conditions is given in Table
2a:
13TABLE 2a Process conditions of 5XPC 27 Concen- Average Reaction
Mol Ratio tration Temperature Pressure Time Batch # (CaO/SiO.sub.2)
(lb/gallon) (.degree. C.) (psi) (hours) 5XPC 27 0.85 0.75 190 163.5
2.5
[0155] The resulting calcium silicate hydrate was tested for
pigment brightness, water absorption, Blaine air permeability and
density, and pH. Both X-ray diffraction and Scanning Electron
Micrograph analyses were also performed on this product. The
pigment properties are given in Table 2b. The pigment was evaluated
for its performance in paper by incorporating it into handsheets as
in example 1. The results of the handsheet work are given in Tables
2d and 2e. The X-ray diffraction pattern is given in FIG. 4. The
S.E.M. pictures at 10,000 and 2000 times magnification are given in
FIGS. 5 and 6, respectively.
[0156] The calcium silicate hydride formed under these conditions
had substantially lower brightness and water absorption
characteristics than TiSil Brand CSH set forth in Example 1.
However, it gave much higher sheet bulk and sheet permeability
characteristics. The pigment properties of my novel 5XPC 27 pigment
are given in Table 2b. It appears that this product provided a much
higher sheet bulk. Also, the sheet permeability of this new product
was higher than the Foshagite-Xonotlite complex as described in
Example 1.
14TABLE 2b Pigment Properties of 5XPC 27 Air Air Water Permeability
Permeability G.E. Brightness Absorption Blaine Wt. Blaine time
Batch # (% reflectance) (%) (g) (sec.) 5XPC 27 91.2 360 0.5
17.0
[0157] As the mole ratio of CaO/SiO.sub.2 was reduced to
.about.0.85 and the reaction temperature was lowered to 190.degree.
C., I discovered another unique and useful multiple phase calcium
silicate hydrate material with a distinct and unique X-ray
diffraction pattern. The X-ray diffraction analysis revealed this
product to be a mixture of Riversideite
[Ca.sub.5Si.sub.6O.sub.16(OH).sub.2] and Xonotlite
[Ca.sub.6Si.sub.6O.sub.17(OH).sub.2]. The X-ray diffraction pattern
is given in FIG. 4. The pattern indicated that the powder had one
major phase and one minor phase. The peak summary is shown in Table
2c.
15TABLE 2c X-ray diffraction peak summary for 5XPC 27 Common
Crystallochemical d-spacing d-spacing d-spacing Name Formula
(Major) (Median) (Minor) Riversideite
Ca.sub.5Si.sub.6O.sub.16(OH).sub.2 d = d = 3.58 .ANG. d = 2.80
.ANG. (Phase I) (Major) 3.055 .ANG. xonotlite
Ca.sub.6Si.sub.6O.sub.17- (OH).sub.2 d = d = 4.09 .ANG. d = 2.50
.ANG. (Phase II) (Minor) 3.056 .ANG.
[0158] The major peaks for phase I were found to indicate the
presence of calcium silicate
hydrate--Riversideite--(Ca.sub.5Si.sub.6O.sub.16(OH).sub- .2) with
major peaks at d(.ANG.)=3.055, d(.ANG.)=3.58 and a minor peak at
d(.ANG.)=2.80. For phase II, the pattern indicated the presence of
calcium silicate
hydroxide--Xonotlite--(Ca.sub.6Si.sub.6O.sub.17(OH).sub.- 2) with
major peaks at d(.ANG.)=3.056, d(.ANG.)=4.09 and a minor peak at
d(.ANG.)=2.50. The pigment also contained trace amounts of calcite
(CaCO.sub.3). The other portion of the slurry was tested for the
pigment performance as a filler in paper. The paper was formed into
handsheets and tested using the procedures described in example
1.
[0159] The S.E.M. pictures at 10,000 times and 2000 times are given
in FIGS. 5 and 6. As can be seen in the 10,000.times.magnification
photograph, the product is unlike the previous example. The calcium
silicate hydrate mixture has fibrous and non-fibrous composition
joined possibly by an amorphous portion of silica hydrogel formed
during the initial phase of hydro-thermal reaction.
[0160] The 2000.times.magnification indicates the formation of an
irregular globular particle formed by the fibrous inter-growth of a
series of primary fibrous crystals. The particle size is in the
range of 10-30 microns and the crystals seem to have grown
randomly.
[0161] This multi-phase (primarily Riversideite and Xonotlite)
calcium silicate hydrate gave lower brightness value than that of
Example 1. More significantly, this material gave a much lower
water absorption (around 360% -400%) as well.
[0162] To evaluate performance in paper, handsheets were formed
using this pigment and then tested as in Example 1. The paper
performance results are shown in Tables 2d-g.
[0163] This product, compared to pulp only, gave substantially
higher stiffness and sheet bulk. Unlike the pigment provided in
Example 1, (where Foshagite was the primary component), this second
pigment (where Riversideite and Xonotlite are present) combination
produced a much more open sheet, as shown by the low Gurley
porosity numbers. The optical properties, like brightness, opacity
and scattering coefficient of the sheet decreased.
[0164] Comparing the performance of this second pigment (with
predominantly Riversideite and Xonotlite present) with an alkaline
filler, such as precipitated calcium carbonate, the sheet stiffness
and bulk improved dramatically. The optical properties (sheet
opacity, sheet brightness, etc.) of the handsheets decreased,
however. The decreased optical properties of this new multiphase
product were clearly due to the large particle size and irregular
globular structure as seen in the S.E.M. pictures.
16TABLE 2d Optical property performance of handsheets containing
20% (interpolated) 5XPC 27 and pulp only. Sheet Filler Scattering
Scattering Brightness Opacity Coefficient Coefficient Pigment (ISO)
(ISO) (cm.sup.2/g) (cm.sup.2/g) 5XPC 27 87.86 83.35 449.12 1092.42
Pulp Only 85.19 74.97 292.1 N/A Improvement +3.1% +11.2% +53.8% --
over pulp
[0165]
17TABLE 2e Strength property performance of handsheets containing
20% (interpolated) 5XPC 27 and pulp only. Stiffness Porosity
(Gurley (sec/100 cc Pigment Units) Bulk (cm.sup.3/g) air) 5XPC 27
225.87 2.46 3.92 Pulp Only 136.68 1.47 33.5 Improvement +65.2%
+68.0% -88.3% over pulp
[0166]
18TABLE 2f Optical property performance of handsheets containing
20% (interpolated) 5XPC 27 and 20% (interpolated) PCC. Sheet Filler
Scattering Scattering Brightness Opacity Coefficient Coefficient
Pigment (ISO) (ISO) (cm.sup.2/g) (cm.sup.2/g) 5XPC 27 87.86 83.35
449.12 1092.42 PCC 90.21 89.39 738.55 2546.03 Improvement -2.6%
-6.76% -39.19% -57.09% over PCC
[0167]
19TABLE 2g Strength property performance of handsheets containing
20% (interpolated) of 5XPC 27 and 20% (interpolated) PCC. Stiffness
Porosity Tensile (Gurley Bulk (sec/100 cc Index Pigment Units)
(cm.sup.3/g) air) (Nm/g) 5XPC 27 225.87 2.46 3.92 29.67 PCC 102.11
1.65 13.23 24.77 Improvement +121.19% +49.22% -70.39% +19.79% over
PCC
[0168] Thus, this multiphase combination of calcium silicate
hydrate was most useful in improving sheet stiffness and sheet
bulk. It was also excellent for "opening up" the sheet (lowering
the Gurley porosity) for more "breathing." Due to its excellent
stiffness, I refer to this product as "StiSil Brand CSH."
EXAMPLE 3
Varying Reaction Temperature (XPC 119)
[0169] Initially, 39.9 grams of pebble lime was weighed accurately
and added slowly to 1.2 L of water in a beaker with constant
agitation. The amount of lime, water, and the rate of lime addition
were controlled in an effort to keep the slurry from boiling due to
the exothermic nature of the lime slaking reaction. The slaked lime
of Ca(OH).sub.2 was screened in a 200 mesh screen. The residual
material was then discarded. The filtered Ca(OH).sub.2 slurry was
tested by acidic titration to calculate the exact amount of
available lime. The slaked lime was then transferred into a 2 liter
autoclave. Then, 31.06 grams of ultrafine, calcined diatomaceous
earth was added to 200 ml of water in order to produce a slurry of
0.1553 g/L concentration. This slurry was also preheated with
constant stirring and brought to near boiling (near 100.degree.
C.). Next, the silica was added to the autoclave containing the hot
slaked lime slurry. The total solids concentration of the
CaO+SiO.sub.2 slurry inside the autoclave, at this point was
.about.0.5 lbs/gallon. The mol ratio of lime to silica was 1.67
CaO/SiO.sub.2. The high-pressure reactor was sealed and then heated
by an externally, jacketed, electrical heating element.
[0170] The autoclave was simultaneously agitated at a constant
speed magnetic drive motor at 600 RPM. The autoclave was heated
until a preset temperature of 220.degree. C. was reached. At that
point the reaction conditions were held constant by a system
controller, RX-32. The CaO+SiO.sub.2 slurry was reacted at a
temperature of 220.degree. C. for 120 minutes. At the end of this
time, the "quenching" water was passed through a cooling system
built into the inside of the autoclave. Inside the pressure vessel,
steam condensed and the temperature fell rapidly. The cooling water
continued until the vessel reached approximately 80.degree. C.
[0171] The silicate slurry was transferred into a holding beaker.
The following describes the overall heating/cooling cycle (see FIG.
5):
[0172] Time to temperature.about.100 minutes
[0173] Time at temperature.about.120 minutes
[0174] Time for cooling.about.25 minutes
[0175] A portion of the slurry was tested for the following
properties:
[0176] 1) X-Ray Diffraction Analysis
[0177] 2) Scanning Electron Microscope (S.E.M)
[0178] 3) Brightness
[0179] 4) Water Absorption
[0180] 5) Blaine Air Permeability (ASTM/ASTM C204-78a)
[0181] Sample Weight (g)--Indication of Bulk Density
[0182] Time (in sec) for a fixed volume of air to pass through the
volume of sample--Indication of particle packing or structure
[0183] The reaction conditions and pigment properties are given in
Tables 3a and 3b respectively.
EXAMPLE 4
Varying Reaction Temperature (XPC 107)
[0184] In this example, all the reaction conditions and parameters
were identical to example 3 above, except for the reaction
temperature was raised from 220.degree. C. to 233.degree. C. The
resultant calcium silicate hydrate complex was then tested as per
the above-described test program and the resultant reaction
conditions and pigment properties are given in Tables 3a and 3b
respectively.
EXAMPLE 5
Varying Reaction Temperature (XPC 124)
[0185] In this example, all of the reaction conditions and
parameters were kept constant, as in example 3, except for reaction
temperature. The reaction temperature was raised from 233.degree.
C. to 243.degree. C. The calcium silicate hydrate complex formed
was tested as in the above examples. The reaction conditions and
pigment properties are given in Tables 3a and 3b respectively.
20TABLE 3a Reaction conditions for Examples 3, 4, and 5. Mole Temp
Reaction Ratio Conc. (degrees Time Example # Batch ID
(CaO/SiO.sub.2) (lbs/gal) C.) (hours) Example 3 XPC 119 1.67 0.7
220.0 2 Example 4 XPC 107 1.67 0.7 233.0 2 Example 5 XPC 124 1.67
0.7 243.0 2
[0186]
21TABLE 3b Pigment properties for Examples 3, 4, and 5. Water
Blaine Blaine Absorption Brightness Wt. Time Example # (%) (ISO)
(grams) (sec.) PH Example 3 440 94.2 0.5 94 11.6 Example 4 440 96.2
0.45 118.5 10.7 Example 5 580 94.9 0.35 94.9 11.5
[0187] Note that the mid range reaction temperature of 233.degree.
C. produced the highest brightness material.
EXAMPLE 6
Varying the CaO/SiO.sub.2 mol Ratio (XPC 130)
[0188] In this example, all the reaction parameters were kept
constant, as in example 4, except for the CaO/SiO.sub.2 mol ratio.
The CaO/SiO.sub.2 mol ratio was changed to 1.4.
[0189] Then, 69.0 g of SiO.sub.2 and 78.0 g of CaO were mixed to
give a CaO/SiO.sub.2 mol ratio of 1.4. The two slurries, CaO and
SiO.sub.2 were mixed in the autoclave. The concentration in the
autoclave was adjusted by adding water to 0.7 lb/gal. The reaction
was carried out for two hours and the autoclave was cooled and the
product was handled as in example 1. The reaction temperature was
kept constant at 233.degree. C. The reaction mixture was agitated
at a constant speed via a magnetic drive motor attached to the
autoclave. The motor was rotated at 600 RPM. The final product was
tested for key parameters and the reaction conditions and key
pigment properties are shown in Tables 4a and 4b respectively.
EXAMPLE 7
Varying the CaO/SiO.sub.2 mol Ratio (XPC 132)
[0190] In this example, all the reaction parameters were kept
constant as in example 4, except the CaO/SiO.sub.2 mol ratio was
raised to 1.6. The hydrothermal reaction was carried out using the
same cycle of heating and cooling as in the previous examples and
the final product was again tested for key pigment properties. The
reaction conditions and key pigment properties are shown in Tables
4a and 4b respectively.
EXAMPLE 8
Varying CaO/SiO.sub.2 mol Ratio (XPC 134)
[0191] Here again, the reaction parameters were all held constant,
as in example 4, except for the CaO/SiO.sub.2 mol ratio, which was
raised to 1.8. The hydrothermal reaction was carried out using the
same cycle of heating and cooling as in the previous examples and
the final product was again tested for key pigment properties. The
reaction conditions and key pigment properties are shown in Tables
4a and 4b respectively.
22TABLE 4a Reaction conditions for Examples 6, 7, and 8. Mole Temp.
Reaction Ratio Conc. (degrees Time Example # Batch #
(CaO/SiO.sub.2) (lbs/gal) C.) (hours) Example 6 XPC 130 1.4 0.7
233.0 2 Example 7 XPC 132 1.6 0.7 233.0 2 Example 8 XPC 134 1.8 0.7
233.0 2
[0192]
23TABLE 4b Pigment properties for Examples 6, 7, 8. Water Blaine
Blaine Absorption Brightness Wt. Time Example # (%) (ISO) (grams)
(sec.) pH Example 6 380 94.7 0.45 112 10.9 Example 7 420 94.1 0.45
51.9 11.4 Example 8 400 94.7 0.5 57.8 11.7
[0193] Note that a CaO/SiO.sub.2 mole ratio of 1.6 produced a
calcium silicate hydrate with the highest water absorption
capability.
EXAMPLE 9
Varying Reaction Time (XPC 172)
[0194] In this example, all the process conditions were kept
constant, as in example 7, except for the reaction time, which was
lowered to 1 hour. The calcium silicate hydrate complex was tested
as in the previous examples and the reaction conditions and key
pigment properties are shown in Tables 5a and 5b respectively.
EXAMPLE 10
Varying Reaction Time (XPC 173)
[0195] In this example, all the process conditions were kept
constant, as in example 9, except for the reaction time, which was
raised to 2 hours. The calcium silicate hydrate complex was tested
as in the previous examples and the reaction conditions and key
pigment properties are shown in Tables 5a and 5b respectively.
EXAMPLE 11
Varying Reaction Time (XPC174)
[0196] In this example, all the process conditions were kept
constant, as in example 9, except for the reaction time, which was
raised to 3 hours. The calcium silicate hydrate complex was tested
as in the previous examples and the reaction conditions and key
pigment properties are shown in Tables 5a and 5b respectively.
24TABLE 5a Reaction conditions for Examples 9, 10, and 11. Mole
Temp. Reaction Ratio Conc. (degrees Time Example # Batch #
(CaO/SiO.sub.2) (lbs/gal) C.) (hours) Example 9 XPC 172 1.67 0.7
233.0 1 Example 10 XPC 173 1.67 0.7 233.0 2 Example 11 XPC 174 1.67
0.7 233.0 3
[0197]
25TABLE 5b Pigment properties for Examples 9, 10 and 11. Water
Blaine Blaine Absorption Brightness Wt. Time Example # (%) (ISO)
(grams) (sec.) PH Example 9 480 92.9 0.5 74 11.1 Example 10 520
96.1 0.45 108.5 11.0 Example 11 600 93.3 0.4 135.0 11.2
[0198] Note that a reaction time of 2 hours produced the highest
brightness product. The longer reaction time of 3 hours produced
the greatest water absorption values, but at a lower
brightness.
EXAMPLE 12
Varying CaO-SiO.sub.2 Slurry Concentration (XPC 136)
[0199] In this example, all the reaction conditions were kept
constant, as in Example 7, except for the CaO/SiO.sub.2 slurry
concentration, which was lowered to 0.4 lb/gallon. To start, 49.6 g
of lime was slaked, screened, and titrated for available CaO. Then,
34.2 g of ultra-fine fluxed calcined diatomaceous earth was
slurried. The fluxed calcined diatomaceous earth slurry was added
to the lime slurry to give the mixture an initial CaO/SiO.sub.2 mol
ratio of 1.6. The reactants were then placed in a 2.0 liter
autoclave and water was added to bring the final concentration of
CaO+SiO.sub.2 slurry up to 0.4 lb/gallon. The reaction temperature
was set at 233.degree. C. The autoclave was set and controlled
using a temperature controller for both heating and cooling cycles
as shown in FIG. 9. The silica-lime slurry was reacted at
233.degree. C. for two hours. At the end of the reaction, the
resulting calcium silicate hydrate was cooled by circulating water
through the jacketed autoclave. The resulting mass was transferred
to a holding beaker. The product was tested for the same key
parameters and with the same methods as described in example 3. The
reaction conditions and key pigment properties are shown in Tables
6a and 6b, respectively.
[0200] EXAMPLE 13
Varying CaO--SiO.sub.2 Slurry Concentration (XPC 138)
[0201] In this reaction, all the reaction parameters were kept
constant, as in example 12, except for the CaO+SiO.sub.2 slurry
concentration, which was raised to 0.6 lb/gallon. The product was
tested as in Example 3 and the reaction conditions and key pigment
properties are shown in Tables 6a and 6b, respectively.
EXAMPLE 14
Varying CaO--SiO.sub.2 Slurry Concentration (XPC 140)
[0202] In this reaction, all the reaction parameters were kept
constant, as in example 12, except for the CaO+SiO.sub.2 slurry
concentration, which was raised to 0.8 lb/gallon. The product was
tested as in example 3 and the reaction conditions and key pigment
properties are shown in Tables 6a and 6b, respectively.
EXAMPLE 15
Varying CaO--SiO.sub.2 Slurry Concentration (XPC 141)
[0203] In this reaction, all the reaction parameters were kept
constant, as in example 12, except for the CaO/SiO.sub.2 slurry
concentration, which was raised to 0.9 lb/gallon. The product was
tested as in example 3 and the reaction conditions and key pigment
properties are shown in Tables 6a and 6b, respectively.
26TABLE 6a Reaction conditions for Examples 12, 13, 14, 15. Mole
Temp. Reaction Ratio Conc. (degrees Time Example # Batch #
(CaO/SiO.sub.2) (lbs/gal) C.) (hours) Example 12 XPC 136 1.6 0.4
233 2 Example 13 XPC 138 1.6 0.6 233 2 Example 14 XPC 140 1.6 0.8
233 2 Example 15 XPC 141 1.6 0.9 233 2
[0204]
27TABLE 6b Pigment properties for Examples 12, 13, 14, 15. Water
Blaine Absorption Brightness Wt. Blaine Time Example # (%) (ISO)
(grams) (sec.) pH Example 480 93.9 0.45 93.7 11.4 12 Example 460
94.6 0.50 173.0 10.4 13 Example 560 96.7 0.35 75.1 10.7 14 Example
420 94.2 0.45 45.7 11.6 15
[0205] Note that the slurry concentration of 0.8 lb/gallon produced
the highest brightness and the lowest bulk density.
EXAMPLE 16
(5XPC 52)
[0206] In this example, the same procedures described in example 1
were used, except that the siliceous raw material was changed.
Instead of using diatomaceous earth, a source of 100% pure silica
was used (trade name: Min-U-Sil). The reaction was carried out at a
very low CaO--SiO.sub.2 slurry concentration of 0.2 lb/gallon. The
resultant calcium silicate hydrate complex was tested for the same
key pigment properties as in example 1 above. The reaction
conditions and key pigment properties are given in Tables 7a and
7b, respectively.
EXAMPLE 17
(5XPC 55)
[0207] In this example, the same procedures described in example 16
were used (including using the pure silica for a siliceous source).
The only difference here was that the CaO--SiO.sub.2 slurry
concentration was raised to 0.4 lb/gallon, and the temperature was
kept at 232.degree. C. The calcium silicate hydrate complex formed
from this reaction was tested as in example 16 above. The reaction
conditions and key pigment properties are given in Tables 7a and
7b.
28TABLE 7a Reaction conditions for Examples 16 and 17. Average
Reaction Mol Ratio Conc. Temp. Pressure Time Batch #
(CaO/SiO.sub.2) (lb/gallon) (.degree. C.) (psi) (hours) 5XPC 52
1.31 0.25 245 490 2 5XPC 55 1.31 0.4 232 387 2
[0208]
29TABLE 7b Pigment Properties Examples 16 and 17 Air Perm. Water
Air Perm. Blaine G.E. Brightness Absorption Blaine time Batch # (%
reflectance) (%) Wt. (g) (sec.) 5XPC 52 96.2 920 5XPC 55 95.1
840
EXAMPLE 18
Sodium Silicate (5XPC 57)
[0209] In this example, all the reaction procedures were kept
constant as in example 1. The only difference was the addition of a
different siliceous raw material source. Here, 20 parts of the
fluxed calcined diatomaceous earth were replaced by liquid sodium
silica Na.sub.2O--SiO.sub.2 ratio of 1:3 (P.Q. "N" product). The
overall CaO/SiO.sub.2 mol ratio was kept at 1.31, the concentration
of the CaO--SiO.sub.2 slurry was kept at 0.5 lb/gallon, and all the
other reaction conditions were kept the same as well. This product
was also tested according to the procedures in example 1. The
reaction conditions and key pigment properties are given in Tables
8a and 8b, respectively.
30TABLE 8a Reaction conditions for Examples 18. Tempera- Average
Reaction Mol Ratio Concentration ture Pressure Time Batch #
(CaO/SiO.sub.2) (lb/gallon) (.degree. C.) (psi) (hours) 5XPC 1.31
0.5 245 375 2 57
[0210]
31TABLE 8b Pigment Properties Examples 18. Air Air Water
Permeability Permeability GE Brightness Absorption Blaine Wt.
Blaine time Batch # (% reflectance) (%) (g) (sec.) 5XPC 57 97.0 680
0.35 57.5
[0211] Note that the most significant difference between this
product and the previous example is the high brightness values
produced.
EXAMPLE 19
(TiSil Brand CSH vs. PCC)
[0212] Application of multi phase calcium silicate hydrate complex
comprising predominantly Foshagite, Ca.sub.4 (SiO.sub.3).sub.3
(OH).sub.2 and some Xonotlite, Ca.sub.6Si.sub.6O.sub.17(OH).sub.2
in paper according to the following process conditions. My novel
calcium silicate hydrate complex, referred to as TiSil Brand CSH,
was applied in paper handsheets. It was compared to commercial PCC
(SMI's Albacar(HO)) and a mixture of PCC and approximately 60 lbs.
per ton TiO.sub.2. The results of the testing are given in Table 9a
and 9b. The graphs showing the performance of TiSil compared to PCC
are given in FIGS. 6 through 13. Improvement by TiSil over PCC is
given in Tables 9c. TiSil Brand CSH gave the following improvement
at 20% ash and equal brightness:
32TABLE 9a Optical property performance of handsheets containing
20% (interpolated) TiSil and 20% (interpolated) PCC. Sheet Filler
Scattering Scattering Brightness Opacity Coefficient Coefficient
Pigment (ISO) (ISO) (cm.sup.2/g) (cm.sup.2/g) TiSil 87.2 92.3 858.0
3065.1 PCC 90.0 89.0 716.8 2507.0
[0213]
33TABLE 9b Strength property performance of handsheets containing
20% (interpolated) of TiSil and 20% (interpolated) PCC. Stiffness
Porosity (Gurley (sec/100 cc Tensile Pigment Units) Bulk
(cm.sup.3/g) air) Index (Nm/g) TiSil 135.3 1.78 47.5 30.0 PCC 113.4
1.58 26.0 29.0
[0214]
34TABLE 9c Handsheet results for TiSil vs. PCC Opacity +2.13%
Scattering Power of sheet +16.2% Filler Scattering Coefficient +24%
Bulk +9% Porosity +220% Stiffness +38.0% Tensile Strength Index
+22.0%
[0215] The TiSil brand CSH pigment seemed to improve a combination
of properties, which were heretofore unattainable. For example, if
sheet bulk was improved, sheet porosity would usually drop. In
addition, if sheet bulk was obtained by having a larger particle
size, optical properties would be significantly reduced. With my
novel pigment, it is the unique composition and structure of the
pigment that allows improvement in key paper properties like higher
bulk and lower porosity.
EXAMPLE 20
(TiSil Brand CSH vs. PCC with 60 lb/ton TiO.sub.2)
[0216] In this example, the calcium silicate hydrate from example 1
(5XPC12) was compared with a mixture of SMI's Albacar(HO)
containing 60 lb/ton TiO.sub.2. The results of the paper testing
are placed in Tables 10a and 10b. The graphical representations of
the data are given in FIGS. 18 through 25. The improvement TiSil
gave over the PCC+TiO.sub.2 mixture (@ 20% ash level and equal
brightness) is given in Table 10c.
35TABLE 10a Optical property performance of handsheets containing
20% (interpolated) TiSil and 20% (interpolated) PCC + TiO.sub.2
combination. Sheet Filler Scattering Scattering Brightness Opacity
Coefficient Coefficient Pigment (ISO) (ISO) (cm.sup.2/g)
(cm.sup.2/g) TiSil 87.2 92.3 858.0 3065.1 PCC with 90.0 89.0 716.8
2507.0 TiO.sub.2
[0217]
36TABLE 10b Strength property performance of handsheets containing
20% (interpolated) of TiSil and 20% (interpolated) PCC + TiO.sub.2
combination. Stiffness Porosity Tensile (Gurley Bulk (sec/100 cc
Index Pigment Units) (cm.sup.3/g) air) (Nm/g) TiSil 135.3 1.78 47.5
30.0 PCC with 113.4 1.58 26.0 29.0 TiO.sub.2
[0218]
37TABLE 10c Handsheet results - TiSil vs. PCC + TiO.sub.2
combination Opacity by 0.5% Scattering Power of sheet by 3.0%
Filler Scattering Coefficient by 4.0% Bulk by 8.2% Porosity by
40.0% Stiffness by 26.0% Tensile by 221.0%
[0219] Here, TiSil Brand CSH has demonstrated exceptional
scattering power for light, an unusual ability to close up the
sheet (higher Gurley porosity) and a significant improvement in
sheet bulk, stiffness, and tensile index.
EXAMPLE 21
(TiSil Brand CSH vs. Bulkite--XPC65)
[0220] In this example, the pigment of my invention, namely a
calcium silicate hydrate complex (Foshagite-Xonotlite complex) was
manufactured under the conditions given in Table 11a. The pigment
was tested for brightness, water absorption, Blaine, and pH. The
results are given in Table 11b. This product was compared as a
paper-making pigment with commercially available calcium silicate,
(Trade name Bulkite). The graphical representation of the results
are given in FIGS. 26-30. The comparison of the two pigments,
XPC-65 and Bulkite at 20% ash is given in Table 11c. The
improvement over Bulkite at 20% ash (interpolated) is given in
Table lid.
38TABLE 11a Reaction conditions for Example 21. Tem- Reaction Mol
Ratio Concentration perature Time Example # Batch # (CaO/SiO.sub.2)
(lb/gallon) (.degree. C.) (hours) Example XPC 65 1.67 0.71 232 2
21
[0221]
39TABLE 11b Pigment properties for Example 21. Water Absorption
Brightness Blaine Wt. Blaine Time Example # (%) (ISO) (grams)
(sec.) PH Example 21 420 93.7 0.45 46.2 10.7
[0222]
40TABLE 11c Optical property performance of handsheets containing
20% (interpolated) XPC 65 and Bulkite. Sheet Filler Scattering
Scat. Porosity Opacity Coefficient Coeff. Brightness (sec/100 cc
Pigment (ISO) (cm.sup.2/g) (cm.sup.2/g) (ISO) air) XPC - 65 90.9
845.4 3109.6 90.0 42.4 Bulkite 84.2 460.9 1273.4 86.4 4.9
[0223]
41TABLE 11d Summary of TiSil Improvement over Bulkite Opacity by
7.2% Scattering Power of sheet by 83.0% Filler Scattering
Coefficient by 144.0% Brightness by 4.13% Porosity by 770.0%
[0224] Once again, this product shows substantially significant
improvement over industry standard pigments.
EXAMPLE 22
(XPC 117) Application in Newsprint
[0225] In this example, the multi-phase CSH Foshagite--Xonotlite
was made by the same procedure as in Example 1, using the process
conditions in Table 12a below.
42TABLE 12a Reaction conditions for Example 22. Tempera- Reaction
Example Batch Mol Ratio Concentration ture Time # # (CaO/SiO.sub.2)
(lb/gallon) (.degree. C.) (hours) Example XPC 1.67 0.67 224 2 22
117
[0226] The product was tested for brightness, water absorption,
Blaine and pH. The results are given in Table 12b.
43TABLE 12b Pigment properties for Example 22. Water Absorption
Brightness Blaine Wt. Blaine Time Example # (%) (ISO) (grams)
(sec.) pH Example 22 470 95.3 0.45 184.7 10.6
[0227] The calcium silicate hydrate complex of this invention was
added to newsprint furnish (20% kraft, 80% TMP). To compare the
performance of the product of my invention, handsheets were made
using commercially available calcium silicate (Hubersil, JM Huber
Co.) and a precipitated calcium carbonate (also by JM Huber Co).
The newsprint sheets containing these pigments were tested for the
following:
[0228] Sheet bulk, stiffness, porosity, smoothness, brightness,
opacity and several print quality parameters like ink strike
through, show through and overall print through. Sheets were also
tested for the static coefficient of friction.
[0229] The actual values, interpolated to 6% ash, are given in
Tables 12c and 12d. A comparison of the product of my invention and
Huber's PCC and HuberSil gave the differences shown in Tables 12e
and 12f. The corresponding bar graphs at 6.0% interpolated ash are
given in FIGS. 31 through 39.
44TABLE 12c Optical property performance of handsheets containing
6% (interpolated) TiSil, HuberSil, and Huber Carbonate. Normalized
Opacity Ink Show Print Pigment (ISO) Penetration Through Through
TiSil 86.29 1.46 4.67 6.13 HuberSil 85.33 1.60 5.14 6.74 Huber
86.75 2.46 4.79 7.24 Carbonate
[0230]
45TABLE 12d Strength property performance of handsheets containing
6% (interpolated) TiSil, HuberSil, and Huber Carbonate. Static
Sheet Porosity Tensile Stiffness Coeff. Smoothness (sec/100 cc
Index (Gurley of (Sheffield Pigment air) (Nm/g) Units) Friction
Units) TiSil 15.40 25.57 22.08 0.90 159.76 HuberSil 11.93 21.95
24.31 0.90 176.02 Huber 11.36 25.32 18.06 0.86 164.06 Carbonate
[0231]
46TABLE 12e Summary of Improvement over Huber Carbonate Opacity
-0.53% Ink Penetration 40% less (better) Show through 2.0% less
(better) Overall print through 15.0% less (better) Porosity +35.0%
(better) Tensile even Stiffness +22% (better) Static coefficient of
friction +5.0% (better)
[0232] A comparison of my new multi-phase CSH products with Huber's
calcium silicate gave the following:
47TABLE 12f Summary of Improvement over HuberSil Opacity +1.1
points Ink Penetration 9.0% less (better) Show through 9.0% less
(better) Overall print through 9.0% less (better) Porosity +29.0%
(better) Tensile +16.0% (better) Shefield smoothness 10.0% less
(better)
[0233] Once again, my multi-phase CSH product gives better paper
and printing properties than currently available commercial calcium
carbonate and commercial calcium silicate fillers.
[0234] During testing of my novel multi-phase calcium silicate
hydrate products, conventional industry quality control standards
were observed. Brightness was tested by using a GE/TAPPI Brightness
Meter, Model S-4. Where applicable, the pH was tested with a pH
meter utilizing TAPPI method T-667. Pulp beating was performed
using a Valley Beater according to TAPPI Method T-200. Handsheets
were produced using a British Handsheet Mold according to TAPPI
Method T-205. Handsheet testing was for tensile strength used a one
inch strip and otherwise was conducted according to TAPPI method
T-220. Where applicable, freeness was tested utilizing a Canadian
Standard Freeness tester according to TAPPI standard T-227. Ashing
tests were conducted at 500.degree. C. according to TAPPI Method
T-211. Air permeability testing was conducted by Blaine, ASTM
Method C204. Available lime was measured according to ASTM Method
C25. For fine paper testing, a standard pulp slurry was made up of
75% hardwood and 25% softwood. Both pulp sources were beaten
separately, in a Valley Beater, to a specific Canadian Standard
Freeness of 450.+-.10 in accordance with TAPPI test methods T-200
and T-227. For newsprint testing, a standard newsprint pulp slurry
was made up of 20% softwood kraft fibers, and 80% thermo-mechanical
pulp. Both pulp sources were received with Canadian Standard
Freeness values of 180 csf .+-.25. This freeness value was deemed
sufficient and no further beating was performed on the pulp. For
the disintegration of the was performed on the pulp. For the
disintegration of the stock pulp solutions, hot water was added to
help relax the pulp fibers and prevent fiber clumps in the final
sheet. Handsheets were formed from the above prepared stock, on a
6" British handsheet mold, in accordance with TAPPI test method
T-205. However, since the goal of producing these handsheets was to
test filler performance, some filler was incorporated into the
handsheets at various replacement levels (usually 15%, 20%, and
25%). In order to achieve comparability between different
replacement levels, a constant basis weight was achieved via a
reduction in fiber content. Thus, a 25% filled sheet contained only
75% of the fiber that the unfilled sheet has. Also, a retention aid
was utilized to hold the filler in the sheet until the sheet had
dried completely. All other handsheet formation components were
kept consistent with TAPPI test method T-205. Handsheets utilizing
titanium dioxide in fine paper were similarly formed, except that
they required double the amount of retention aid as required by the
other fillers. In addition, when TiO.sub.2 was added in conjunction
with another filler, it was necessary to first add TiO.sub.2, then
add one dose of retention aid, and then add the filler and a second
dose of retention aid. Handsheets formed for newsprint testing were
prepared in a similar method to the fine paper handsheets. However,
different filler loading levels were utilized, and the newsprint
sheets were usually loaded at 3%, 6%, and 9% filler. The handsheets
were tested in accordance with TAPPI test method T-220, except that
a 25.4 mm sample was used and the tensile index calculations were
recalculated accordingly. Handsheets were ashed in accordance with
TAPPI test method T-211.
[0235] In summary, the unique crystalline microfibres produced as a
product of the reactions described herein exist, in one unique
product, as bundles sized from about 10 to about 40 microns,
typically occurring as haystacks or balls. Preferably, individual
fibers are about 0.2 microns in the largest cross-sectional
dimension, with lengths of up to 4 or 5 microns, so as to have a
relatively large L/D ratio.
[0236] Importantly, the crystalline microfibers as just described
have advantageous properties when utilized as a paper filler,
particularly in uncoated groundwood, and in coated groundwood, in
uncoated fine paper, and in coated fine paper. The aforementioned
adsorptive properties help to adsorb printing ink in the papers.
Also, it helps the paper sheet itself to absorb fines, so that it
improves overall sheet retention during the papermaking process.
Overall, final paper products exhibit improved porosity, improved
smoothness, improved bulk, and improved stiffness. Also, brightness
and opacity are maintained or improved. Moreover, the printability
of the final product is significantly improved, due to the improved
ink adsorption.
[0237] It is to be appreciated that my unique, light, fluffy
adsorptive calcium silicate hydrate products, and the method of
producing the same, and the paper products produced using such
products, each represent an appreciable improvement in the paper
production arts. Although only a few exemplary embodiments of this
invention have been described in detail, those skilled in the art
may find that the processes described herein, and the products
produced thereby, may be modified from those embodiments provided
herein, without materially departing from the novel teachings and
advantages provided.
[0238] It will thus bee seen that the objects set forth above,
including those made apparent from the preceding description, are
efficiently attained. Since certain changes may be made in carrying
out production of the CSH products, and the unique paper products
produce therewith, it is to be understood that my invention may be
embodied in other specific forms without departing from the spirit
or essential characteristics thereof. Many other embodiments are
also feasible to attain advantageous results utilizing the
principles disclosed herein. Therefor, it will be understood that
the foregoing description of representative embodiments of the
invention have been presented only for purposes of illustration and
for providing an understanding of the invention, and are not
intended to be exhaustive or restrictive, or to limit the invention
to the precise embodiments disclosed. The intention is to cover all
modifications, equivalents, and alternatives falling with the scope
and spirit of the invention, as expressed herein above and in the
appended claims. As such, the claims are intended to cover the
products, processes, methods, and equivalent processes and methods.
The scope of the invention, as described herein, is thus intended
to included variations from the embodiments provided which are
nevertheless described by the broad meaning and range properly
afforded to the language herein, and as explained by and in light
of the terms included herein, or by the legal equivalents
thereof.
* * * * *