U.S. patent number 10,385,246 [Application Number 15/378,777] was granted by the patent office on 2019-08-20 for dust control formulations.
This patent grant is currently assigned to Henry Company, LLC. The grantee listed for this patent is Henry Company, LLC. Invention is credited to Amba Ayambem.
United States Patent |
10,385,246 |
Ayambem |
August 20, 2019 |
Dust control formulations
Abstract
This disclosure describes formulations and methods for dust
control, for example, coal topping, a term which refers to the
application of liquid products to the top of coal loads, such as
those in open topped coal hopper railcars as commonly used today to
transport coal. Disclosed herein are wax-based emulsion
formulations that accomplish dust control during industrial
operations in which dust handling is required.
Inventors: |
Ayambem; Amba (Kimberton,
PA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Henry Company, LLC |
El Segundo |
CA |
US |
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Assignee: |
Henry Company, LLC (El Segundo,
CA)
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Family
ID: |
59021040 |
Appl.
No.: |
15/378,777 |
Filed: |
December 14, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170166792 A1 |
Jun 15, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62266778 |
Dec 14, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B
20/1033 (20130101); C04B 40/0039 (20130101); C04B
24/08 (20130101); C09K 3/22 (20130101); C10L
5/24 (20130101); E21F 5/06 (20130101); C04B
40/0039 (20130101); C04B 24/005 (20130101); C04B
24/08 (20130101); C04B 24/36 (20130101); C04B
24/42 (20130101); C04B 2103/0079 (20130101); C04B
2103/40 (20130101); C04B 2103/408 (20130101); C04B
2103/67 (20130101); C04B 20/1033 (20130101); C04B
24/005 (20130101); C04B 24/08 (20130101); C04B
24/36 (20130101); C04B 24/42 (20130101); C04B
2103/0079 (20130101); C04B 2103/40 (20130101); C04B
2103/408 (20130101); C04B 2103/67 (20130101); C10L
2290/18 (20130101); C10L 2250/04 (20130101); C04B
2103/0075 (20130101); C10L 2230/14 (20130101) |
Current International
Class: |
C09K
3/22 (20060101); C10L 5/24 (20060101); C04B
40/00 (20060101); E21F 5/06 (20060101); C04B
20/10 (20060101); C04B 24/08 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McAvoy; Ellen M
Assistant Examiner: Graham; Chantel L
Attorney, Agent or Firm: BakerHostetler
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Patent
Application No. 62/266,778, filed on Dec. 14, 2015, which is
incorporated by reference herein in its entirety. This application
is also related to U.S. patent application Ser. Nos. 15/197,047 and
15/274,258, filed on Jun. 29, 2016 and Sep. 23, 2016, respectively.
Claims
What is claimed:
1. A method for controlling dust on a surface of a bulk material,
comprising: (I) preparing a dust control formulation (DCF)
comprising a dust reduction additive (DRA) emulsion comprising
colloidally-protected wax-based (CPWB) microstructures; and (II)
applying said dust control formulation to said surface of said bulk
material in an amount effective for dust control, wherein said CPWB
microstructure comprises: (A) a wax core, wherein said wax core
comprises a paraffin component and a non-paraffin component,
wherein said paraffin component comprises at least one linear
alkane wax defined by the general formula CnH2n+2, where n ranges
from 13-80, wherein said non-paraffin component comprises at least
one wax selected from the group consisting of animal-based wax,
plant-based wax, mineral wax, synthetic wax, a wax containing
organic acids and/or esters, anhydrides, an emulsifier containing a
mixture of organic acids and/or esters, and combinations thereof;
and (B) a polymeric shell, wherein said polymeric shell comprises
at least one polymer selected from poly-vinyl alcohol, polyvinyl
alcohol copolymers, polyvinyl alcohol terpolymers, polyvinyl
acetate, polyvinyl acetate copolymers, polyvinyl acetate
terpolymers, cellulose ethers, polyethylene oxide,
polyethyleneimines, polyvinylpyrrolidone, polyvinylpyrrolidone
copolymers, polyethylene glycol, polyacrylamides and poly
(N-isopropylamides), pullulan, sodium alginate, gelatin, starches,
and combinations thereof.
2. The method as recited in claim 1, wherein said polymeric shell
comprises polyvinyl alcohol.
3. The method as recited in claim 1, wherein said DCF further
comprises a binder; a preservative; a rheology modifier; and/or a
surfactant.
4. The method as recited in claim 1, wherein said binder is
selected from polyvinyl acetate, polyvinyl alcohol, ethylene vinyl
acetate co-polymer, vinylacrylic copolymer, styrenebutadiene,
polyacrylamide, acrylic polymers, latex, natural starch, synthetic
starch, casein, and combinations thereof.
5. The method as recited in claim 1, wherein said dust-reduction
additive emulsion further comprises a second water; a base; and a
dispersant.
6. The method as recited in claim 4, wherein said dispersant is
selected from a dispersant having sulfur; a dispersant having a
sulfur-containing group in the compound; sulfonic acid
(R--S(.dbd.O).sub.2--OH); sulfonic acid salts, wherein the R groups
is functionalized with hydroxyl, or carboxyl; lignosulfonate;
lignosulfonic acid; naphthalene sulfonic acid; sulfonate salt of
lignosulfonic acid; sulfonate salt of naphthalene sulfonic acid,
derivatized lignosulfonic acid, derivatized naphthalene sulfonic
acid, functionalized lignosulfonic acid; functionalized naphthalene
sulfonic acid; magnesium sulfate; polycarboxylate; ammonium hepta
molybdate; combination of ammonium hepta molybdate and starch,
alkyl quaternary ammonium; montmorillonite clay; non-ionic
surfactants; ionic surfactants; zwitterionic surfactants; and
mixtures thereof.
7. The method as recited in claim 4, wherein said base is selected
from monoethanol amine; diethanol amine; triethanol amine;
imidazole; potassium siliconate; and combinations thereof.
8. The method as recited in claim 1, wherein the weight of said
dust reduction additive emulsion is in the range of from about
0.01% to about 20% by weight of said dust control formulation.
9. The method as recited in claim 1, wherein the weight of said
dust reduction additive emulsion is in the range of from about 0.1%
to about 10% by weight of said dust control formulation.
10. The method as recited in claim 1, wherein said dust control
formulation further comprises at least one component from a
silicone, a siliconate, a fluorinated compound, a stearate, or a
combination thereof.
11. The method as recited in claim 10, wherein the silicones,
siliconates, fluorinated compounds, or stearates are selected from
the group consisting of metal siliconate salts, potassium
siliconate, poly hydrogen methyl siloxane, polydimethyl siloxane,
stearate-based salts, and combinations thereof.
12. The method as recited in claim 1, wherein said dust control
formulation is applied to the surface of said bulk material at the
rate of from about 0.001 to about 5.0 gallon per square yard for
controlling dust.
13. The method as recited in claim 1, wherein said bulk material is
coal, limestone, fly ash, cement, carbon black, coke, or mineral
material.
14. The method as recited in claim 1, wherein said bulk material is
coal, and said dust control formulation is applied the top of said
coal load in an open-topped, coal-hopper railcar, used for
transporting coal.
15. The method as recited in claim 1, wherein said dust control
formulation is applied by sprinkling, and/or a spray nozzle.
16. The method as recited in claim 1, wherein said dust control
formulation further comprises a first water.
Description
TECHNICAL FIELD
The present invention relates to dust control compositions. More
specifically, the invention is directed to dust-inhibiting
concentrates and other solutions containing wax emulsions. This
disclosure describes formulations and methods for dust control, for
example, coal topping, a term which refers to the application of
liquid products to the top of coal loads, such as those in open
topped coal hopper railcars as commonly used today to transport
coal. Disclosed herein are wax-based emulsion formulations that
accomplish dust control during industrial operations in which dust
handling is required.
BACKGROUND
Many industrial operations create fugitive dust. Because it can be
airborne, fugitive dust is an environmental and health hazard and
in some cases, even a fire hazard. Airborne dust can also mean loss
of usable material. Also, the airborne particles are highly
pervasive and can enter the nose, lungs, eyes and even the pores of
the skin. Industrial operations requiring dust prevention include
dumping of material, transportation, transfer point operation,
stockpiling, storage, re-claiming, conveyoring, shearing,
continuous mining, crushing, screening and sifting, drying,
packaging and filling.
All types of dust including soil particles, industrial products,
by-products and waste, coal dust, road dust and many others present
hazards. Some examples of particulate materials that produce dust
include for example, ground limestone (10 to 1000 .mu.m); fly ash
(10 to 200 .mu.m); coal dust (1 to 100 .mu.m); cement dust (3 to
100 .mu.m); carbon black (0.01 to 0.3 .mu.m); and pulverized coal
(3 to 500 .mu.m).
For example, the high speed transportation of coal by rail may
cause loss of fine coal particles. In fact, coal trains are known
as "black snakes." The name aptly describes the miles of uncovered
rail cars bearing the black cargo as they slither along the tracks.
During the journey from coal mines to their final destinations,
coal trains shed plumes of coal dust from the tops of the train
cars. As the dust spews from the rail cars, it fills the
surrounding air. with harmful substances like mercury, lead,
cadmium, arsenic, manganese, beryllium, and chromium. When the dust
settles, these substances are deposited in soil and water, harming
plant, animal, and marine life.
Both train vibration and airspeed (from wind or due to the speed of
train) can lift particles from exposed coal making them airborne
and depositing them along the right-of-way and transporting them by
wind considerable distances. In addition to environmental hazards,
health hazards and product loss, coal dust lost during
transportation can also damage transportation infrastructure.
Environmental consequences from coal dust are also rooted in
railroad safety concerns. Coal dust accumulation in the ballast can
destabilize the tracks and contribute to derailments. Derailments
impact the environment because the overturned train can spill
locomotive fuel and dump thou-sands of pounds of coal and coal
dust, resulting in soil and water contamination.
Fugitive dust problem avails itself to two solutions: (1) lowered
dust creation; and (2) dust control through prevention,
suppression, capture, or removal.
This invention relates to the second solution, that is, dust
control. Dust control can be approached in four ways: (1) using wet
systems that use water sprays to prevent dust or capture airborne
dust; (2) using enclosures to contain dust; (3) using ventilation
systems/exhaust systems to remove dust; (4) using a combination of
these techniques. More specifically, this invention relates to a
novel wax-based emulsion formulations in wet spray systems that can
assist in dust control.
Halide brines, comprising one or more dissolved or suspended salts
in water, usually halide salts, especially chloride salts,
particularly calcium chloride, magnesium chloride and other alkali
metal and alkaline earth metal salts, are used extensively for
inhibiting dust on a variety of surfaces including such uses as
dust control of roadways, paved areas, bridges and the like as well
as for inhibiting dust on surfaces of bulk materials, such as coal,
coke, limestone and minerals. They are also used for dust control,
especially during dry weather during the handling and
transportation of dust-producing bulk materials, such as coal, coke
and limestone.
Aqueous solutions of these halides are known to corrode metals and
cause scaling or surface damage to concrete. For example, heavy use
of road deicers can result in serious damage to steel, particularly
autos and other vehicles, as well as rapid deterioration of steel
reinforcing rods in poured concrete roadways and bridges. The
halides used for dust control of bulk materials such as coal or
other minerals often cause corrosive deterioration of the
materials-handling equipment, rail cars and other container
carriers.
In accordance with the present invention, it has been found that a
formulation comprising wax emulsions resists absorption into pores
of coal and other mineral surfaces, including soil, so that after
drying into a continuous or discontinuous film, the wax emulsion
will provide later dust control, as well as exhibiting dust control
and anti-corrosion properties upon later wetting with water.
The composition of the present invention addresses the above
discussed problems of dust generation. The emulsion of the present
invention comprising colloidally-protected, wax-based
micro-structure can be added to a water based spray system that can
then be used for spraying on to the particulate material, for
example, coal, to control the dust.
SUMMARY
This invention relates to a method for controlling dust on a
surface of a bulk material, comprising:
(I) preparing a dust control formulation (DCF) comprising a dust
reduction additive (DRA) emulsion comprising colloidally-protected
wax-based (CPWB) microstructures; and
(II) applying said dust control formulation to said surface of said
bulk material in an amount effective for dust control.
This invention also relates to the above method, wherein said dust
control formulation is applied by sprinkling, and/or a spray
nozzle.
This invention further relates to the above methods, wherein said
dust control formulation further comprises a first water.
This invention also relates to the above methods, wherein said CPWB
microstructure comprises:
(A) a wax core,
wherein said wax core comprises a paraffin component and a
non-paraffin component,
wherein said paraffin component comprises at least one linear
alkane wax defined by the general formula CnH2n+2, where n ranges
from 13-80,
wherein said non-paraffin component comprises at least one wax
selected from the group consisting of animal-based wax, plant-based
wax, mineral wax, synthetic wax, a wax containing organic acids
and/or esters, anhydrides, an emulsifier containing a mixture of
organic acids and/or esters, and combinations thereof; and
(B) a polymeric shell,
wherein said polymeric shell comprises at least one polymer
selected from polyvinyl alcohol, polyvinyl alcohol copolymers,
polyvinyl alcohol terpolymers, polyvinyl acetate, polyvinyl acetate
copolymers, polyvinyl acetate terpolymers, cellulose ethers,
polyethylene oxide, polyethyleneimines, polyvinylpyrrolidone,
polyvinylpyrrolidone copolymers, polyethylene glycol,
polyacrylamides and poly (N-isopropylamides), pullulan, sodium
alginate, gelatin, starches, and combinations thereof.
In one embodiment, this invention further relates to above methods,
wherein said polymeric shell comprises polyvinyl alcohol.
In yet another embodiment, this invention further relates to above
methods, wherein said DCF further comprises a binder; a
preservative; a rheology modifier; and/or a surfactant.
In one embodiment, this invention further relates to above methods,
wherein:
said binder is selected from polyvinyl acetate, polyvinyl alcohol,
ethylene vinyl acetate co-polymer, vinylacrylic copolymer,
styrenebutadiene, polyacrylamide, acrylic polymers, latex, natural
starch, synthetic starch, casein, and combinations thereof.
In another embodiment, this invention further relates to above
methods, wherein said dust-reduction additive emulsion further
comprises a second water; a base; and a dispersant.
In one embodiment, this invention further relates to above methods,
wherein said dispersant is selected from a dispersant having
sulfur; a dispersant having a sulfur-containing group in the
compound; sulfonic acid (R--S(.dbd.O)2-OH); sulfonic acid salts,
wherein the R groups is functionalized with hydroxyl, or carboxyl;
lignosulfonate; lignosulfonic acid; naphthalene sulfonic acid;
sulfonate salt of lignosulfonic acid; sulfonate salt of naphthalene
sulfonic acid; derivatized ligno-sulfonic acid; derivatized
naphthalene sulfonic acid; functionalized lignosulfonic acid;
functionalized naphthalene sulfonic acid; magnesium sulfate;
polycarboxylate; ammonium hepta molybdate; combination of ammonium
hepta molybdate and starch; alkyl quaternary ammonium;
montmorillonite clay; non-ionic surfactants; ionic surfactants;
zwitterionic surfactants; and mixtures thereof.
In another embodiment, this invention further relates to above
methods, wherein said base is selected from monoethanol amine;
diethanol amine; triethanol amine; imidazole; potassium siliconate;
and combinations thereof.
Furthermore, this invention further relates to above methods,
wherein the weight of said dust reduction additive emulsion is in
the range of from about 0.01% to about 20% by weight of said dust
control formulation.
In one embodiment, this invention further relates to above methods,
wherein the weight of said dust reduction additive emulsion is in
the range of from about 0.1% to about 10% by weight of said dust
control formulation.
In one embodiment, this invention further relates to above methods,
wherein said dust control formulation further comprises at least
one component from a silicone, a siliconate, a fluorinated
compound, a stearate, or a combination thereof.
In another embodiment, this invention relates to the above methods,
wherein the silicones, siliconates, fluorinated compounds, or
stearates are selected from the group consisting of metal
siliconate salts, potassium siliconate, poly hydrogen methyl
siloxane, polydimethyl siloxane, stearate-based salts, and
combinations thereof.
In yet another embodiment, this invention further relates to above
methods, wherein said dust control formulation is applied to the
surface of said bulk material at the rate of from about 0.001 to
about 5.0 gallon per square yard for controlling dust.
In one embodiment, this invention further relates to above methods,
wherein said bulk material is coal, limestone, fly ash, cement,
carbon black, coke, or mineral material.
In another embodiment, this invention further relates to above
methods, wherein said bulk material is coal, and said dust control
formulation is applied the top of said coal load in an open-topped,
coal-hopper railcar, used for transporting coal.
This invention also relates to a concentrated dust control
formulation, suitable for dust control upon dilution with water
consisting essentially of water and about 5-80% weight of dust
control additive emulsion comprising colloidally-protected
wax-based (CPWB) microstructures.
BRIEF DESCRIPTION OF THE DRAWINGS
The disclosed aspects will hereinafter be described in conjunction
with the appended Drawings, provided to illustrate and not to limit
the disclosed aspects, wherein like designations denote the
elements.
FIG. 1 illustrates an example process of one embodiment of the
disclosure.
FIG. 2 describes the particle model of a unitary wax particle that
has been stabilized in the colloidal dispersion.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
The terms "approximately", "about", and "substantially" as used
herein represent an amount close to the stated amount that still
performs a desired function or achieves a desired result. For
example, the terms "approximately", "about", and "substantially"
may refer to an amount that is within less than 10% of, within less
than 5% of, within less than 1% of, within less than 0.1% of, and
within less than 0.01% of the stated amount.
The surprising discovery in the method of this invention is the
effect of improved and long-lasting dust control and
corrosion-inhibiting properties resulting from the presence of CPWB
wax emulsion applied to various surfaces. Any surface exposed to
dust-producing conditions can benefit from the method described
herein.
Typical surfaces that require treatment for exposure to
dust-yielding conditions are mineral, e.g., coal mines, coal, coke
or limestone being transported by rail car, roadways, pavements,
paved and unpaved open areas such as stock yards, bridges and the
like. Coal, coke, limestone and other minerals may also produce
dust that must be contained so as to limit pollution of the
environment.
In accordance with a preferred embodiment of the methods described
herein, the solution of CPWB wax emulsion in water is used to bind
dust particles to larger particles, particularly on mineral, e.g.,
coal, mine floors and on coal during transport via uncovered rail
cars. On mineral mine floors and as a surface covering for coal and
other dust-producing minerals being transported in uncovered rail
cars, the CPWB wax emulsion preferably has a concentration of about
0.1 wt. % to about 2 wt. % to bind smaller mineral particles to
larger mineral particles. The CPWB wax emulsion coating resists
absorption of the solution into the pores of the larger mineral
particles and the CPWB wax emulsion absorbs water from the
atmosphere and resists water evaporation to maintain the binding
capability of the CPWB for continued binding of smaller mineral
particles to larger mineral particles, even during movement and
settling during transport.
If repeated applications of the CPWB wax emulsion solution are
needed, such as on a roadway surface during construction, the CPWB
wax emulsion concentration increases with each application to
maintain the soil surface damp for an unexpectedly long period of
time, e.g., about four times or more as long as using water only.
The CPWB wax emulsion compositions described herein can be applied
as CPWB wax emulsion in water. Alternatively, the composition can
be provided as a slurry containing wax emulsion.
In the method of dust control, the DCF is applied to a surface of
the material requiring dust control. One preferred rate of
application is from about 0.001 to 5.0 gallons of admixture per
square yard of surface treated. Rates vary according to the surface
receiving the application. With unpaved roads, for example, the
rate of application can be adjusted within a preferred range of 0.1
to 1.5 gallon of blend to one square yard of road. Treatment rates
of application for other surfaces are known in the art.
The admixture can be applied to the surfaces of roads, bridges or
bulk substances carried in open containers by any of several
methods known in the art. One preferred method is sprinkling of the
admixture solution over the surface requiring freeze conditioning
or dust control. Another preferred method is spraying the admixture
by nozzles, preferably pressurized nozzles, so that the mechanical
action of the spray provides complete coverage of the admixture
into unpaved road surfaces, coal, coke, limestone, and the like.
Other known methods can be used to apply the admixture.
General Embodiments
There are several constraints that apply to a dust control
formulation such as a coal topper formulations. A tensile strength
high enough to resist cracking when subjected to shocks and wind
during transport is preferred. For the same reason, greater
flexibility is also preferred. Due to the cost of water, a low
water requirement is preferred. A relatively higher depth of
penetration, which is directly related to the viscosity of the coal
topper formulation, is preferred to bind as much coal mass at the
surface as possible. Viscosity is related to the ability of the
polymer fluid to penetrate the surface of the subject media. In
particular coal particulates, which have different wetting
properties than normal soil or rock particulate, will reject fluid
with excessive viscosity while accepting lower viscosity fluid. It
is speculated that a hydrophobic mechanism may play a part,
possible a result of the hydrocarbon interaction with the coal
topper. In addition, the coal topper formulation must not inhibit
the ability to unload or burn the coal. A coal topper should not
excessively corrode the transport equipment such as the railcars or
loading/unloading equipment.
The dust control formulations of the present invention serve all of
the above advantages. Embodiments of the present disclosure provide
a dust control additive ("DCA") comprising colloidally-protected,
wax-based ("CPWB") microstructures in an emulsion form. In another
embodiment, the present invention relates to the process of
preparing such dust control additive emulsions. Dust control
additive refers to any ingredient capable of preventing,
minimizing, suppressing, reducing, or inhibiting the formation of
particles capable of becoming airborne. The expressions "airborne
particles" or "airborne dust particles" refer to fine particles
generated during the many industrial and/or other process
operations such as dumping of material, transportation, transfer
point operation, stockpiling, storage, reclaiming, conveyoring,
shearing, continuous mining, crushing, screening and sifting,
drying, packaging, filling, sanding and abrading While the
disclosure infra describes the DCA of the present invention in the
context of coal topping, the DCA emulsion can also be used with
other particulate materials where airborne particles are
generated.
The present invention also relates to dust control formulations
comprising the dust control additive and methods for preparing such
dust control formulations. By "dust control formulation" (DCF) is
meant a formulation such as a spray comprising DCA emulsion which
helps in control of airborne particles. According to the present
invention, there are provided dust control formulations suitable
for spraying and applying to particulate materials requiring dust
control. The compositions of the present invention include a dust
control additive combined with other ingredients to form an aqueous
system, or a non-aqueous system including fillers, binders, and/or
thickeners to form a DCF.
In addition to providing a dust control property, the DCF of the
present invention may also be hydrophobic, and thus,
water-resistant. Further, the embodiments of the present invention
also provide adhesive properties to particulate material to which
it is added.
The DCF may be used to create a low-dust, water resistant barrier
over the materials on which it is sprayed thereby reducing the dust
generated during process and preventing moisture from passing
through the material. In one embodiment, the DCF comprises the dust
control additive that comprises an activated montan and polyvinyl
alcohol-stabilized wax emulsion described further below. By doing
so, the resulting dried DCF coated surface can exhibit a low-dust
environment and high contact angle, which can lead to exceptional
water repellency. Further, the disclosed DCF formed from a wax
emulsion can assist with adhesion.
The DCF can be used on various materials such as ground limestone
(10 to 1000 .mu.m); fly ash (10 to 200 .mu.m); coal dust (1 to 100
.mu.m); cement dust (3 to 100 .mu.m); carbon black (0.01 to 0.3
.mu.m); and pulverized coal (3 to 500 .mu.m).
In accordance with a characterizing feature of the present
invention, the DCF comprises the DCA emulsion which minimizes the
quantity of airborne particles generated, for example, during
operation of industrial processes. The DCA generally comprises less
than 20% of the DCF wet weight. More preferably, the dust control
additive comprises between about 0.1% and about 10% of the dust
control formulation by wet weight percent and, most preferably,
between about 1.5% and about 6%. In one embodiment, the DCA is
selected from any one of the following weight percentages:
0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, and 20.
The weight percentage of DCA emulsion in the DCF can be any number
within the range defined by any two numbers above, including the
endpoints.
In one embodiment, the DCA emulsion is in the range of from about
0.01 to 1% by weight of the DCF. Stated another way, the DCA
emulsion is selected from any one of the following percentages:
0.01, 0.02, 0.03, . . . 0.09, 0.1, 0.11, 0.12, . . . , 0.97, 0.98,
0.99, 1.00. The weight percentage of DCA emulsion in the DCF can be
any number within the range defined by any two numbers above,
including the endpoints. The dust control additive of the present
invention is described in detail infra.
Many ingredients have been found to effectively reduce the quantity
of airborne particles generated, including oils such as animal,
vegetable, and mineral oils (saturated and unsaturated), and oils
derived from petroleum, pitch, natural and synthetic waxes,
paraffins, solvents which evaporate slower than water, terpenes,
glycols, surfactants, and mixtures thereof. However, the CPWB
microstructure based DCA emulsion of the present invention unlocks
the synergistic effect of the three desired properties in the DCF,
namely, dust control property, water resistance, and adhesion. Dust
control additive may cause the dust particles to agglomerate or
stick together, thereby forming large heavy particles which tend
not to become or remain airborne.
Dust Control Additive
Definitions
For the purposes of this invention, a "colloidal dispersion" is a
dispersion of a discontinuous phase in a continuous phase,
comprising colloidally-protected wax-based microstructures.
By "wax" is meant any naturally occurring or synthetically
occurring wax. It also includes blends or mixtures of one or more
naturally occurring and/or synthetically occurring waxes. Those of
animal origin typically consist of wax esters derived from a
variety of carboxylic acids and fatty alcohols. The composition
depends not only on species, but also on geographic location of the
organism. Because they are mixtures, naturally produced waxes are
softer and melt at lower temperatures than the pure components.
Waxes are further discussed infra.
By "emulsion" or "wax-based emulsion" is meant an aqueous
colloidally occurring dispersion or mixture in a liquid or
paste-like form comprising wax materials, which has both the
discontinuous and the continuous phases, preferably as liquid. For
example, an aqueous wax system can either be a general colloid, or
it can be an emulsion (which is a type of colloid), depending on
the melt temperature of the emulsified wax versus the use
temperature. In the disclosure below, the term "emulsion" is used.
It should be noted, however, that a colloidal dispersion is also
within the scope of the present invention.
By "colloidally-protected wax-based microstructure" (CPWB
microstructure) is meant a colloidal dispersion or emulsion,
wherein the microstructure is colloidally protected with a wax or a
lower fraction hydrocarbon core. The microstructure can exist in a
dispersion or emulsion form.
Colloidally-Protected Wax-Based Microstructures
This invention relates to DCA materials that comprise CPWB
microstructures, preferably in an emulsion form. They have been
alternatively called "CPWB microstructure based DCA emulsion," or
"DCA emulsion," or "DCA emulsion comprising CPWB microstructure."
CPWB microstructures have a wax core and film or casing of
polymeric moieties which are adhered to the core via secondary
forces such as Van Der Waals forces as opposed to a mechanical
shell over a core in a classical core-shell structure. CPWB
microstructures are described in detail below. In the aqueous
emulsion of the DCA comprising the CPWB microstructures, the core
may be fully or partially encapsulated, in that the colloidal shell
is not a physical shell like that of a typical core-shell
structure. The DCA emulsion comprising CPWB microstructure provides
low-dust property, adhesion property and water resistance property
to the material to which it is added.
CPWB Microstructure Shell
The polymers selected for the shell of the CPWB microstructures for
low-dust joint compound applications are one or more of the
following:
Polyvinyl alcohol and copolymers, cellulose ethers, polyethylene
oxide, polyethyleneimines, polyvinylpyrrolidone, and copolymers,
polyethylene glycol, polyacrylamides and poly (N-isopropylamides,
pullulan, sodium alginate, gelatin, and starches. Polyvinyl alcohol
and copolymers are preferred.
CPWB Microstructure Core
The core of the colloidally-protected wax-based microstructures can
be a paraffin wax that is a linear alkane with a general formula of
C.sub.nH.sub.2n+2, wherein n varies from 13 to 80. The paraffin wax
defined by n=13 is called tridecane and the one with n=80 is
octacontane. The melting point of C.sub.13 wax is -5.4.degree. C.
Similarly, the melting point of the C.sub.60 wax is 100.degree. C.
Similarly, the melting point of higher waxes (between C.sub.60 and
C.sub.80) is higher than 100.degree. C. but lower than the melting
point of the colloidally-protective polymeric shell.
Some embodiments of the present invention envision wax that
comprises branched structures as well as a blend or mixture of
linear and branched structures of the wax. This invention also
embodies mixtures or blends of waxes with two or more carbon
numbers that may either be linear, branched, or blends of linear
and branched structures. For example, a wax could be a mixture of
C.sub.15 linear and C.sub.20 linear hydrocarbon alkane wax. In
another example, the wax could be a mixture of C.sub.16 linear and
C.sub.16 branched hydrocarbon alkane wax. In yet another example,
the wax could be a mixture of C.sub.15 linear, C.sub.16 linear, and
C.sub.20 branched. In yet another example, the wax could be a
mixture of C.sub.18 linear, C.sub.18 branched.
Waxes usable as core in the CPWB microstructure-based DCA emulsion
of the present invention are described.
Waxes
For the purposes of the present invention, waxes include naturally
occurring waxes and synthetic waxes. Naturally occurring waxes
include plant based waxes, animal waxes, and mineral waxes.
Synthetic waxes are made by physical or chemical processes.
Examples of plant based waxes include mixtures of unesterified
hydrocarbons, which may predominate over esters. The epicuticular
waxes of plants are mixtures of substituted long-chain aliphatic
hydrocarbons, containing alkanes, alkyl esters, sterol esters,
fatty acids, primary and secondary alcohols, diols, ketones,
aldehydes, aliphatic aldehydes, primary and secondary alcohols,
.beta.-diketones, triacylglycerols, and many more. The nature of
the other lipid constituents can vary greatly with the source of
the waxy material, but they include hydrocarbons. Specific examples
of plant wax include Carnauba wax, which is a hard wax obtained
from the Brazilian palm Copemicia prunifera, which contains the
ester myricyl cerotate. Other plant based waxes include candelilla
wax, ouricury wax, jojoba plant wax, bayberry wax, Japan wax,
sunflower wax, tall oil, tallow wax, rice wax, and tallows.
Animal wax includes beeswax as well as waxes secreted by other
insects. A major component of the beeswax used in constructing
honeycombs is the ester myricyl palmitate which is an ester of
triacontanol and palmitic acid. Spermaceti occurs in large amounts
in the head oil of the sperm whale. One of its main constituents is
cetyl palmitate, another ester of a fatty acid and a fatty alcohol.
Lanolin is a wax obtained from wool, consisting of esters of
sterols. Other animal wax examples include lanocerin, shellac, and
ozokerite.
Examples of mineral waxes include montan wax, paraffin wax,
microcrystalline wax and intermediate wax. Although many natural
waxes contain esters, paraffin waxes are hydrocarbons, mixtures of
alkanes usually in a homologous series of chain lengths. Paraffin
waxes are mixtures of saturated n- and iso-alkanes, naphthenes, and
alkyl- and naphthene-substituted aromatic compounds. The degree of
branching has an important influence on the properties. Montan wax
is a fossilized wax extracted from coal and lignite. It is very
hard, reflecting the high concentration of saturated fatty
acids/esters and alcohols. Montan wax includes chemical components
formed of long chain alkyl acids and alkyl esters having chain
lengths of about 24 to 30 carbons. In addition, natural montan
includes resin acids, polyterpenes and some alcohol, ketone and
other hydrocarbons such that it is not a "pure" wax. The
saponification number of montan, which is a saponifiable wax, is
about 92 and its melting point is about 80.degree. C.
Other waxes include petroleum waxes derived from crude oil after
processing, which include macrocrystalline wax, microcrystalline
wax, petrolatum and paraffin wax. Paraffin wax is formed
principally of straight-chain alkanes having average chain lengths
of 20-30 carbon atoms.
Waxes comprising esters and/or acids may act as emulsifiers to the
paraffins.
Synthetic waxes include waxes based on polypropylene, polyethylene,
and polytetrafluoroethylene. Other synthetic waxes are based on
fatty acid amines, Fischer Tropsch, and polyamides, polyethylene
and related derivatives. Some waxes are obtained by cracking
polyethylene at 400.degree. C. The products have the formula
(CH.sub.2).sub.nH.sub.2, where n ranges between about 50 and
100.
Also outside of the building products context, in addition to waxes
that occur in natural form, there are various known synthetic waxes
which include synthetic polyethylene wax of low molecular weight,
i.e., molecular weights of less than about 10,000, and
polyethylenes that have wax-like properties. Such waxes can be
formed by direct polymerization of ethylene under conditions
suitable to control molecular weight. Polyethylenes with molecular
weights in about the 2,000-4,000 range are waxes, and when in the
range of about 4,000-12,000 become wax resins.
Fischer-Tropsch waxes are polymethylene waxes produced by a
particular polymerization synthesis, specifically, a
Fischer-Tropsch synthesis (polymerization of carbon monoxide under
high pressure, high temperature and special catalysts to produce
hydrocarbon, followed by distillation to separate the products into
liquid fuels and waxes). Such waxes (hydrocarbon waxes of
microcrystalline, polyethylene and polymethylene types) can be
chemically modified by, e.g., air oxidation (to give an acid number
of 30 or less and a saponification number no lower than 25) or
modified with maleic anhydride or carboxylic acid. Such modified
waxes are more easily emulsified in water and can be saponified or
esterified. Other known synthetic waxes are polymerized
alpha-olefins. These are waxes formed of higher alpha-olefins of 20
or more carbon atoms that have wax like properties. The materials
are very branched with broad molecular weight distributions and
melting points ranging about 54.degree. C. to 75.degree. C. with
molecular weights of about 2,600 to 2,800. Thus, waxes differ
depending on the nature of the base material as well as the
polymerization or synthesis process, and resulting chemical
structure, including the use and type of any chemical
modification.
Various types of alpha-olefin and other olefinic synthetic waxes
are known within the broad category of waxes, as are chemically
modified waxes, and have been used in a variety of applications,
outside the water-resistant wallboard area. They are of a wide
variety and vary in content and chemical structure. As noted above,
water-resistant wallboard products generally use paraffin, paraffin
and montan, or other paraffinic or synthetic waxes as described
above in the mentioned exemplary patent references. In one
embodiment of the invention, the wax used for the preparation of
the dispersion or emulsion is used in a micronized, pulverized
form. U.S. Pat. Nos. 8,669,401 and 4,846,887 show exemplary
micronization processes. Both these patents are incorporated by
reference herein as if fully set forth.
In one embodiment, the emulsifiers for this invention include
montan wax, esters/acids, styrene-maleic anhydride, polyolefin
maleic anhydride, or other anhydrides, carnauba wax, rice wax,
sunflower wax.
Theory for Colloidally-Protected Wax-Based Microstructures
Generally speaking, two scientific theories have been proposed to
explain the stability of CPWB microstructures that comprise the DCA
emulsion materials of the present invention, namely, steric
hindrance and electrostatic repulsion. Applicants do not wish to be
bound by these theories, however. Applicants believe their
invention relates to wax-based dispersions that may or may not
relate to the two theories. It is possible that one or both
theories or neither of the two may explain the CPWB microstructures
of the present invention.
As described in FIG. 1, in the first step, a colloidally-protected
wax based microstructures in an emulsion are prepared. The emulsion
is prepared according to the specification for their use in variety
of applications. For a general understanding of the method of
making the exemplary wax emulsion, reference is made to the flow
diagram in FIG. 1. As shown in 101, first the wax components may be
mixed in an appropriate mixer device. Then, as shown in 102, the
wax component mixture may be pumped to a colloid mill or
homogenizer. As demonstrated in 103, in a separate step, water, and
any emulsifiers, stabilizers, or additives (e.g., ethylene-vinyl
alcohol-vinyl acetate terpolymer) are mixed. Then the aqueous
solution is pumped into a colloid mill or homogenizer in 104. Steps
101 and 103 may be performed simultaneously, or they may be
performed at different times. Steps 102 and 104 may be performed at
the same time, so as to ensure proper formation of droplets in the
emulsion. In some embodiments, steps 101 and 102 may be performed
before step 103 is started. Finally, as shown in 105, the two
mixtures from 102 and 104 are milled or homogenized to form an
aqueous wax-based emulsion.
FIG. 2 describes the particle model of a unitary wax particle that
has been stabilized in the colloidal dispersion. Applicants do not
wish to be bound by the theory of the unitary wax particle
stabilized in the dispersion. According to this model, the
hydrophobic hydrocarbon "tail" of the montan is embedded in the
paraffin particle. The "head" of montan, which is hydrophilic is
then tethered to polyvinyl alcohol. The first mechanism by which
many of the wax emulsions (colloidal dispersions) are stabilized is
the steric hindrance mechanism. According to this mechanism, high
molecular weight polymers (e.g. PVOH) are tethered to the outer
surface of a wax particle and surround it. Due to steric hindrance,
the PVOH molecules surrounding each wax particle then prevent
adjacent wax particles from coalescing.
Alternatively, electrostatic repulsion helps with the stabilization
of the colloidal dispersions. In this mechanism, the wax particle,
which contains acid or ester groups (either inherently or mixed
in), is first saponified with a base, converting the acid or ester
groups to negatively charged carboxylate moieties. Because of their
polar nature, these negatively charged carboxylate moieties exist
at the water/wax interface, giving the wax particle a net negative
charge. These negative charges on adjacent wax particles then
constitute a repulsive force between particles that effectively
stabilizes the dispersion (emulsion).
Thus, according to one model, as shown in FIG. 2, a wax particle is
enclosed in a "web" of PVOH polymeric chains. This is not akin to a
shell of a typical core-shell particle, but the PVOH loosely
protects (colloidally protects) the wax particle. One could
envision the wax particle as a solid ball or a nucleus surrounded
by polymeric chains like strings.
Thus, according to one model, as shown in FIG. 2, a wax particle is
enclosed in a "web" of PVOH polymeric chains. This is not akin to a
shell of a typical core-shell particle, but the PVOH loosely
protects (colloidally protects) the wax particle. One could
envision the wax particle as a solid ball or a nucleus surrounded
by polymeric chains like strings.
In another embodiment, and as shown in FIGS. 3 and 4, the polymer,
for example PVOH, forms a shell like physical film or casing such
as a film (PVOH is an excellent film former), the casing herein is
based on secondary forces of attraction, e.g., Van der Waals
forces. Hydrogen bonding may also be one of the forces for the
encapsulation of the PVOH of the wax particles. Applicants do not
wish to be bound by this theory. However, the model does explain
the wax particle with the PVOH casing over it. In the above
examples, PVOH is used as an exemplary polymeric system. However,
other polymeric systems used herein, or their combinations can also
be used to prepare the colloidally-protected wax-based
microstructures.
Dust Control Additive Emulsion
Exemplary emulsion comprising CPWB microstructure for use in, for
example, as a dust reduction additive (and for water-resistance) in
a joint compound are now described in greater detail, as
follows.
In one embodiment, the wax emulsion may comprise water, a base, one
or more waxes optionally selected from the group consisting of
slack wax, montan wax, and paraffin wax, and a polymeric
stabilizer, such as ethylene-vinyl alcohol-vinyl acetate terpolymer
or polyvinyl alcohol. Further, carnauba wax, sunflower wax, tall
oil, tallow wax, rice wax, and any other natural or synthetic wax
or emulsifier containing organic acids and/or esters can be used to
form the wax emulsion.
Water may be provided to the emulsion, for example in amounts of
about 30% to about 60% by weight of the emulsion. The solids
content of the wax emulsion is preferably about 40% to about 70% by
weight of the emulsion. Other amounts may be used.
In some embodiments, a dispersant and/or a surfactant may be
employed in the wax emulsions. Optional dispersants, include, but
are not limited to those having a sulfur or a sulfur-containing
group(s) in the compound such as sulfonic acids
(R--S(.dbd.O).sub.2--OH) and their salts, wherein the R groups may
be otherwise functionalized with hydroxyl, carboxyl or other useful
bonding groups. In some embodiments, higher molecular weight
sulfonic acid compounds such as lignosulfonate, lignosulfonic acid,
naphthalene sulfonic acid, the sulfonate salts of these acids, and
derivatized or functionalized versions of these materials are used
in addition or instead. An example lignosulfonic acid salt is
Polyfon.RTM. H available from MeadWestvaco Corporation, Charleston,
S.C. Other dispersants may be used, such as magnesium sulfate,
polycarboxylate technology, ammonium hepta molybdate/starch
combinations, non-ionic surfactants, ionic surfactants,
zwitterionic surfactants and mixtures thereof, alkyl quaternary
ammonium montmorillonite clay, etc. Similar materials may also be
used, where such materials may be compatible with and perform well
with the formulation components.
In one embodiment, a dispersant and/or surfactant may comprise
about 0.01% to about 5.0% by weight of the wax emulsion formulation
composition, preferably about 0.1% to about 2.0% by weight of the
wax emulsion formulation composition. Other concentrations may be
used.
The wax component of the emulsion may include at least one wax
which may be slack wax, or a combination of montan wax and slack
wax. The total wax content may be about 30% to about 60%, more
preferably about 30% to about 40% by weight of the emulsion. Slack
wax may be any suitable slack wax known or to be developed which
incorporates a material that is a higher petroleum refining
fraction of generally up to about 20% by weight oil. In addition
to, or as an alternative to slack wax, paraffin waxes of a more
refined fraction are also useful within the scope of the
invention.
Suitable paraffin waxes may be any suitable paraffin wax, and
preferably paraffins of melting points of from about 40.degree. C.
to about 110.degree. C., although lower or higher melting points
may be used if drying conditions are altered accordingly using any
techniques known or yet to be developed in the composite board
manufacturing arts or otherwise. Thus, petroleum fraction waxes,
either paraffin or microcrystalline, and which may be either in the
form of varying levels of refined paraffins, or less refined slack
wax may be used. Optionally, synthetic waxes such as ethylenic
polymers or hydrocarbon types derived via Fischer-Tropsch synthesis
may be included in addition or instead, however paraffins or slack
waxes are preferred in certain embodiments. The wax emulsion used
in the joint compound can be formed from slack wax, montan wax,
paraffin wax, carnauba wax, tall oil, sunflower wax, rice wax, and
any other natural or synthetic wax containing organic acids and/or
esters, or combinations thereof. For example, synthetic wax used in
the joint compound may comprise ethylenic polymers or hydrocarbon
types, optionally derived via Fischer-Tropsch synthesis, or
combinations thereof. Optionally, the synthetic waxes can be added
in concentrations ranging from about 0.1% to about 8% of the dry
weight of the joint compound or from about 0.5% to about 4.0% of
the dry weight of the joint compound. In some embodiments, the wax
emulsion is stabilized by polyvinyl alcohol.
Montan wax, which is also known in the art as lignite wax, is a
hard, naturally occurring wax that is typically dark to amber in
color (although lighter, more refined montan waxes are also
commercially available). Montan is insoluble in water, but is
soluble in solvents such as carbon tetrachloride, benzene and
chloroform. In addition to naturally derived montan wax, alkyl
acids and/or alkyl esters which are derived from high molecular
weight fatty acids of synthetic or natural sources with chain
lengths preferably of over 18 carbons, more preferably from 26 to
46 carbons that function in a manner similar to naturally derived
montan wax are also within the scope of the invention and are
included within the scope of "montan wax" as that term is used
herein unless the context indicates otherwise (e.g., "naturally
occurring montan wax"). Such alkyl acids are generally described as
being of formula R--COOH, where R is an alkyl non-polar group which
is lipophilic and can be from 18 to more than 200 carbons. An
example of such a material is octacosanoic acid and its
corresponding ester which is, for example, a di-ester of that acid
with ethylene glycol. The COOH group forms hydrophilic polar salts
in the presence of alkali metals such as sodium or potassium in the
emulsion. While the alkyl portion of the molecule gets embedded
within the paraffin, the acid portion is at the paraffin/aqueous
medium interface, providing stability to the emulsion.
In some embodiments, the at least one wax component of the emulsion
includes primarily and, preferably completely a slack wax
component. In some embodiments, the at least one wax component is
made up of a combination of paraffin wax and montan wax or of slack
wax and montan wax. Although it should be understood that varying
combinations of such waxes can be used. When using montan wax in
combination with one or more of the other suitable wax components,
it is preferred that montan be present in an amount of about 0.1%
to about 10%, more preferably about 1% to about 4% by weight of the
wax emulsion with the remaining wax or waxes present in amounts of
from about 30% to about 50%, more preferably about 30% to about 35%
by weight of the wax emulsion.
In some embodiments, the wax emulsion includes polyvinyl alcohol
(PVOH) of any suitable grade which is at least partially
hydrolyzed. The preferred polyvinyl alcohol is at least 50%, and
more preferably at least 90%, and most preferably about 97-100%
hydrolyzed polyvinyl acetate. The PVA can be hydrolyzed to the
extent defined by the percentage numbers below:
50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100.
The PVA can also be hydrolyzed up to the extent of a number that
resides in the range defined by any two numbers above, including
the endpoints.
Suitably, the polyvinyl alcohol is soluble in water at elevated
temperatures of about 60.degree. C. to about 95.degree. C., but
insoluble in cold water. The hydrolyzed polyvinyl alcohol is
preferably included in the emulsion in an amount of up to about 5%
by weight, preferably 0.1% to about 5% by weight of the emulsion,
and most preferably about 2% to about 3% by weight of the wax
emulsion.
In some embodiments, the stabilizer comprises a polymer that is
capable of hydrogen bonding to the carboxylate or similar moieties
at the water/paraffin interface. Polymers that fit the
hydrogen-bonding requirement would have such groups as hydroxyl,
amine, and/or thiol, amongst others, along the polymer chain.
Reducing the polymer's affinity for water (and thus, its water
solubility) could be achieved by inserting hydrophobic groups such
as alkyl, alkoxy silanes, or alkyl halide groups into the polymer
chain. The result may be a polymer such as ethylene-vinyl
acetate-vinyl alcohol terpolymer (where the vinyl acetate has been
substantially hydrolyzed). The vinyl acetate content may be between
0% to 15%. In some embodiments, the vinyl acetate content is
between 0% and 3% of the terpolymer chain. The ethylene-vinyl
alcohol-vinyl acetate terpolymer may be included in the emulsion in
an amount of up to about 10.0% by weight, preferably 0.1% to about
5.0% by weight of the emulsion. In some embodiments, ethylene-vinyl
alcohol-vinyl acetate terpolymer may be included in the emulsion in
an amount of about 2% to about 3% by weight of the wax emulsion. An
example ethylene-vinyl alcohol-vinyl acetate terpolymer that is
available is the Exceval AQ4104.TM., available from Kuraray
Chemical Company.
The dust reduction additive wax emulsion may include a stabilizer
material (e.g., PVOH, ethylene-vinyl alcohol-vinyl acetate
terpolymer as described above). The stabilizer may be soluble in
water at elevated temperatures similar to those disclosed with
reference to PVOH (e.g., about 60.degree. C. up to about 95.degree.
C.), but insoluble in cold water. The active species in the wax
component (e.g., montan wax) may be the carboxylic acids and
esters, which may comprise as much as 90% of the wax. These
chemical groups may be converted into carboxylate moieties upon
hydrolysis in a high pH environment (e.g., in an environment
including aqueous KOH). The carboxylate moieties may act as a
hydrophilic portion or "head" of the molecule. The hydrophilic
portions can directly interface with the surrounding aqueous
environment, while the rest of the molecule, which may be a
lipophilic portion or "tail", may be embedded in the hydrocarbon
wax.
A stabilizer capable of hydrogen bonding to carboxylate moieties
(e.g., PVOH or ethylene-vinyl alcohol-vinyl acetate terpolymer as
described above) may be used in the wax emulsion. The polar nature
of the carboxylate moiety may offer an optimal anchoring point for
a stabilizer chain through hydrogen bonding. When stabilizer chains
are firmly anchored to the carboxylate moieties as described above,
the stabilizer may provide emulsion stabilization through steric
hindrance. In embodiments where the wax emulsion is subsequently
dispersed in a wallboard (e.g., gypsum board) system, all the water
may be evaporated away during wallboard manufacture. The stabilizer
may then function as a gate-keeper for repelling moisture.
Decreasing the solubility of the stabilizer in water may improve
the moisture resistance of the wax emulsion and the wallboard. For
example, fully hydrolyzed PVOH may only dissolve in heated, and not
cool, water. For another example, ethylene-vinyl alcohol-vinyl
acetate terpolymer may be even less water soluble than PVOH. The
ethylene repeating units may reduce the overall water solubility.
Other stabilizer materials are also possible. For example, polymers
with hydrogen bonding capability such as those containing specific
functional groups, such as alcohols, amines, and thiols, may also
be used. For another example, vinyl alcohol-vinyl acetate-silyl
ether terpolymer can be used. An example vinyl alcohol-vinyl
acetate-silyl ether terpolymer is Exceval R-2015, available from
Kuraray Chemical Company. In some embodiments, combinations of
stabilizers are used.
In some embodiments, the wax emulsion comprises a base. For
example, the wax emulsion may comprise an alkali metal hydroxide,
such as potassium hydroxide or other suitable metallic hydroxide,
such as aluminum, barium, calcium, lithium, magnesium, sodium
and/or zinc hydroxide. These materials may serve as saponifying
agents. Non-metallic bases such as derivatives of ammonia as well
as amines (e.g., diethanolamine or triethanolamine) can also be
used. Combinations of the above-mentioned materials are also
possible. If included in the wax emulsion, potassium hydroxide is
preferably present in an amount of 0% to 1%, more preferably about
0.1% to about 0.5% by weight of the wax emulsion.
In some embodiments, an exemplary wax emulsion comprises: about 30%
to about 60% by weight of water; about 0.1% to about 5% by weight
of a lignosulfonic acid or a salt thereof; about 0% to about 1% by
weight of potassium hydroxide; about 30% to about 50% by weight of
wax selected from the group consisting of paraffin wax, slack wax
and combinations thereof; and about 0.1% to about 10% montan wax,
and about 0.1 to 5% by weight of ethylene-vinyl alcohol-vinyl
acetate terpolymer.
The wax emulsion may further include other additives, including
without limitation additional emulsifiers and stabilizers typically
used in wax emulsions, flame retardants, lignocellulosic preserving
agents, fungicides, insecticides, biocides, waxes, sizing agents,
fillers, binders, additional adhesives and/or catalysts. Such
additives are preferably present in minor amounts and are provided
in amounts which will not materially affect the resulting composite
board properties. Preferably no more than 30% by weight, more
preferably no more than 10%, and most preferably no more than 5% by
weight of such additives are present in the wax emulsion.
Shown in the below tables are exemplary embodiments of a wax
emulsion, although other quantities in weight percent may be
used.
TABLE-US-00001 TABLE 1 First Exemplary Embodiment of Dust Reduction
Additive Emulsion Raw Material Quantity in Weight Percent Water 58
Polyvinyl Alcohol 2.70 Dispersant (Optional) 1.50 Paraffin Wax
34.30 Montan Wax 3.50 Biocide 0.02
TABLE-US-00002 TABLE 2 Second Exemplary embodiment of Dust
Reduction Additive Emulsion Raw Material Quantity in Weight Percent
Water 58.80 Polyvinyl Alcohol 2.80 Diethanol Amine 0.04 Paraffin
Wax 34.80 Montan Wax 3.50 Biocide 0.10
The wax emulsion may be prepared using any acceptable techniques
known in the art or to be developed for formulating wax emulsions,
for example, the wax(es) are preferably heated to a molten state
and blended together (if blending is required). A hot aqueous
solution is prepared which includes any additives such as
emulsifiers, stabilizers, etc., ethylene-vinyl alcohol-vinyl
acetate terpolymer (if present), potassium hydroxide (if present)
and lignosulfonic acid or any salt thereof. The wax is then metered
together with the aqueous solution in appropriate proportions
through a colloid mill or similar apparatus to form a wax emulsion,
which may then be cooled to ambient conditions if desired.
In some embodiments, the wax emulsion may be incorporated with or
coated on various surfaces and substrates. For example, the wax
emulsion may be mixed with gypsum to form a gypsum wallboard having
improved moisture resistance properties.
Some or all steps of the above method may be performed in open
vessels. However, the homogenizer may use pressure in its
application.
Advantageously in some embodiments, the emulsion, once formed, is
cooled quickly. By cooling the emulsion quickly, agglomeration and
coalescence of the wax particles may be avoided.
In some embodiments the wax mixture and the aqueous solution are
combined in a pre-mix tank before they are pumped into the colloid
mill or homogenizer. In other embodiments, the wax mixture and the
aqueous solution may be combined for the first time in the colloid
mill or homogenizer. When the wax mixture and the aqueous solution
are combined in the colloid mill or homogenizer without first being
combined in a pre-mix tank, the two mixtures may advantageously be
combined under equivalent or nearly equivalent pressure or flow
rate to ensure sufficient mixing.
In some embodiments, once melted, the wax emulsion is quickly
combined with the aqueous solution. While not wishing to be bound
by any theory, this expedited combination may beneficially prevent
oxidation of the wax mixture.
Dust Control Formulation
Embodiments of the disclosed CPWB microstructure based dust control
additive emulsion can be used to form a dust control formulation
(DCF). The DCF can be used to top coal carrying railcars. It can
also be used in various industrial operations to control the dust
formation, for example, in all coal processes such as size
reduction.
In one embodiment, an appropriately prepared formulation is sprayed
over the coal, which penetrates the materials and binds the
particles that could otherwise be airborne. The DCF can also be
specially formulated to serve as a cover coat on in storage
facilities such as silos and bins and other containers. The DCF can
be particularly useful in locations where there is high
humidity.
The DCF comprises a filler material. Any conventional filler
material can be used in the present invention. Suitable fillers
include calcium carbonate (CaCO.sub.3) and calcium sulfate
dihydrate (CaSO.sub.4 2H.sub.2O commonly referred to as gypsum) for
ready mixed type DCFs, and calcium sulfate hemihydrates
(CaSO.sub.4-1/2 H.sub.2O) for setting type DCFs. The DCF can also
include one or more secondary fillers such as glass micro bubbles,
mica, perlite, talc, limestone, pyrophyllite, silica, and
diatomaceous earth. The filler generally comprises from about 1% to
about 95% of the weight of the DCF based on the total wet weight of
the formulation (i.e. including water). Another ingredient usually
present in DCF is a binder or resin. Suitable binders include
polyvinyl acetate, polyvinyl alcohol, ethylene vinyl acetate
co-polymer, vinylacrylic co-polymer, styrenebutadiene,
polyacrylamide, other acrylic polymers, other latex emulsions,
natural and synthetic starch, and casein. These binders can be used
alone or in combination with one another. The amount of binder can
range from about 1% to about 45% of the DCF total wet weight. More
preferably, the binder comprises from about 1% to about 20% of the
total wet weight, and most preferably, from about 4% to about
14%.
A surfactant can also be included in the DCF formulation. The
surfactant generally comprises less than about 3.5% of the DCF
total wet weight, and preferably less than about 0.25%.
Many DCF formulations also contain a cellulosic thickener, usually
a cellulosic ether. Suitable thickeners include methyl cellulose,
hydroxypropyl cellulose, hydroxypropyl methyl cellulose,
hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl
hydroxypropyl cellulose, ethylhydroxyethyl cellulose, and sodium
carboxymethyl cellulose (CMC). These thickeners can be used alone
or in combination with one another. The amount of cellulosic
thickener can range from about 0.1% to about 2% by weight of the
DCF. A preferred thickener is hydroxypropyl methyl cellulose
available from Dow Chemical Company under the trade designation
Methocel.
Another ingredient that can be included in the DCF of the invention
is a non-leveling agent. Suitable non-leveling agents include clays
such as attapulgus clay, bentonite, illite, kaolin and sepiolite,
and clays mixed with starches. Thickeners, such as those described
above, can also function as non-leveling agents.
Additional ingredients which can be utilized in the DCF are
preservatives, fungicides, anti-freeze wetting agents, defoamers,
flocculants, such as polyacrylamide resin, and plasticizers, such
as dipropylene glycol dibenzoate.
The wax emulsion used in the DCF can be formed from slack wax,
montan wax, paraffin wax, carnauba wax, tall oil, sunflower wax,
rice wax, and any other natural or synthetic wax containing organic
acids and/or esters, or combinations thereof. For example,
synthetic wax used in the DCF may comprise ethylenic polymers or
hydrocarbon types, optionally derived via Fischer-Tropsch
synthesis, or combinations thereof. By way of further example,
synthetic wax used in the DCF may comprise polyethylene glycol,
methoxypolyethylene glycol, or combinations thereof. Optionally,
the synthetic waxes can be added in concentrations ranging from
about 0.1% to about 8% of the dry weight of the DCF or from about
0.5% to about 4.0% of the dry weight of the DCF. In some
embodiments, the wax emulsion is stabilized by polyvinyl
alcohol.
In some embodiments, perlite can be used in a DCF to, for example,
control the density, shrinkage, and crack resistance of the DCF. In
some embodiments, perlite need not be used (e.g., where weight is
not as much of a factor).
In some embodiments, clay can be used in a DCF as, for example, a
non-leveling agent and/or a thickening agent that can control the
viscosity or rheology of the final product. Clay can also help
enhance or create the water-holding properties of the DCF.
In some embodiments, thickeners can be used to control the
viscosity, affect the rheology, and affect the water holding
characteristics of a DCF. For example, cellulose ether can be used
as a thickener.
In some embodiments, binders can be used in a DCF to, for example,
improve bonding to the substrate such as coal.
In some embodiments, a glycol can be used in a DCF to provide
functional such as wet edge, open time, controlling drying time,
and freeze/thaw stability.
In some embodiments, other rheology modifiers can also be used in
conjunction with, or instead of, some of the above described
compositions.
In some embodiments, fillers can be used in the DCF although a
lower viscosity closer to that of water (for spraying purposes) is
preferred. For example, calcium carbonate, calcium sulfate
hemihydrates, or calcium sulfate dehydrated can all be used as
fillers, though other materials can be used as well. Further,
thickeners, preservatives, binders, and other additives can be
incorporated into the DCF.
Other additives can also be added to the described DCF in addition
to the wax emulsion. In some embodiments, metal siliconate salts
such as, for example, potassium siliconate, as well as silicone
based compounds such as, for example, poly hydrogen methyl siloxane
and polydimethyl siloxane, could provide advantageous water
resistance to a DCF. In some embodiments, fluorinated compounds and
stearate-based salts could also be used to provide advantageous
water resistance.
Wax emulsions can be particularly advantageous for use in a DCF as
compared to, for example, non-emulsified and/or non-stabilized
waxes such as melted PEG M750. These non-emulsified waxes can
impart severe deleterious effects on the adhesion properties of a
DCF. Therefore, if the non-emulsified wax is to be used at all, it
must be added in very low levels. On the other hand, wax emulsions,
such as those described herein, can advantageously increase the
adhesion properties of a DCF, at least due to the adhesive effects
of the stabilizer, and thus can be added at higher dosage levels.
The wax emulsions can then be useful as they can provide both dust
control properties as well as water repellency to the DCF and the
substrate on which it is sprayed. The wax emulsion can soften or
melt when friction is applied, such as during transportation and
handling. Accordingly, dust can be agglomerated by the softened wax
emulsion, where it can be securely held.
Embodiments of the DCF can be applied in thin layers to a surface.
The DCF can be applied by, for example, using a spraying device.
However, the application and thickness of the layers of DCF is not
limiting. Further, multiple layers may be applied in order to
obtain an appropriate dust control. The number or layers applied is
not limiting. In some embodiments, each layer can be allowed to dry
prior to application of the next layer. In some embodiments, a
second layer can be applied when the first layer is only partially
dried.
In some embodiments, the DCF can be aqueous. In addition to a latex
binder, other water soluble binders, such as polyvinyl alcohol, can
be used as well. Other materials, such as talc, binders, fillers,
thickening agents, preservatives, limestone, perlite, urea,
defoaming agents, gypsum latex, glycol, and humectants can be
incorporated into the DCF as well or can substitute for certain
ingredients (e.g., talc can be used in place of, or in addition to
mica; gypsum can be used in place of, or in addition to calcium
carbonate, etc.). In some embodiments, the calcium carbonate can be
replaced either wholly or partially with a surface micro-roughened
filler that can further enhance the DCF's hydrophobicity. In some
embodiments, Calcimatt.TM., manufactured by Omya AG, can be used.
In some embodiments, cristobalite (silicon dioxide) such as
Sibelite.RTM. M3000, manufactured by Quarzwekre, can be used. These
fillers can be used alone or in combination.
In some embodiments, the DCF is aqueous and can be applied to the
substrate and can be allowed to dry. Once the water evaporates from
the mixture, a dry, relatively hard cementitious material can
remain. An example formula range of an embodiment of a
water-resistant DCF using the above disclosed wax is shown in the
below Table 3:
TABLE-US-00003 TABLE 3 Exemplary Composition of a DCF Component
Percent Range Water 20-55% Preservatives 0.02-1.0% Calcium
Carbonate 10-50% Mica 0.5-10% Attapulgite Clay 0.2-10% Talc 0.0-10%
Perlite 0.0-40% Polyethylene Oxide 0.0-10% Polyether Siloxane
0.0-10% Wax Emulsion 0.1-20% Latex Binder 0.5-10% Cellulose Ether
Thickener 0.1-8.0%
Further, an example of a specific formulation for a
low-dust/water-resistant DCF can is shown in the below Table 4,
although other weight percentages may be used:
TABLE-US-00004 TABLE 4 Example Composition of a Low-Dust Joint
Compound Compound Wt. % Preservative 0.01 Wetting Agent 0.05 Latex
Binder 5.89 Water 34.60 Wax Emulsion 7.36 Cellulose Ether 0.55
Attapulgite Clay 1.84 Mica 7.36 Calcium Carbonate 33.86 Expanded
Perlite 8.47
Another embodiment of a low-dust/water-resistant ready-mix DCF
formula is shown in the below Table 5. In this embodiment, an
optional potassium siliconate additive is incorporated.
TABLE-US-00005 TABLE 5 Embodiment of DCF Composition Raw Material
Wt. % Preservative 0.20% Latex (CPS 716) 6.50% Water 36.70% Wax
Emulsion 3.80% Potassium Siliconate 0.20% (Silres BS 16) Cellulose
Ether 0.60% Clay (Attagel 30) 1.90% Mica 6.10% Limestone (MW 100)
35.20% SilCel 43-34 8.80%
The DCA emulsion formulation is comprised of a paraffin, an
emulsifier, usually a carboxylic acid or ester that can be
saponified via a reaction with a base, and a stabilizer polyvinyl
alcohol. Suitable emulsifiers were montan wax, rice wax, carnauba
wax, and any such wax that is composed of a mixture of acids and
esters. Standalone acids from C5 to C100, such as stearic acid, can
also be used in place of the aforementioned natural waxes.
Likewise, standalone esters of similar carbon atom chain length can
also be used.
Suitable bases include any compound that is capable of saponifying
the ester carboxylate group, or deprotonating the carboxylic acid
proton. Suitable bases are inorganic basis such as potassium
hydroxide and ammonium hydroxide. Likewise, suitable organic basis
are monoethanol amine, diethanol amine, ad triethanol amine.
When the inventive CPWB microstructure based emulsion is used as a
dust control additive to the DCF, the DCF improves its dust
reduction capability, over and above the simultaneous improvement
in water resistance and adhesion. The DCF's ability to reduce dust
is measured as peak airborne dust production in mg/m3 units, and
for the inventive DCF of the present invention comprising the CPWB
microstructure emulsion, the PAD number is reduced by the following
percentage numbers, depending upon the content of the CPWB
microstructure-based dust control additive emulsion in the DCF10,
15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 75, 80, 85%, 90% and 95%,
and 98%. In some embodiments of the present invention the PAD
number is reduced by a percentage residing in between a range
defined by any two numbers above, including the endpoints of such
range.
The wax emulsion was made by heating the emulsifier and the
paraffin in a vessel such that both become molten. In a separate
vessel, a measured quantity of polyvinyl alcohol was mixed with
water at room temperature after which the mixture was heated to
about 180 F. The molten paraffin/montan mixture was then combined
with the hot water/polyvinyl alcohol mixture which, upon passing
through a charlotte mill, emerged as a stable wax emulsion where
the polyvinyl alcohol was tethered to the paraffin surface, largely
encapsulating the paraffin. A representative formula of the wax
emulsion is shown in Table 6.
TABLE-US-00006 TABLE 6 Representative Formula of CPWB
Microstructure Based Inventive Wax Emulsion Ingredient Content %
Water 60.3 Polyvinyl alcohol 3 Paraffin wax 33.5 Montan wax 3
Monoethanol amine 0.2 Total Wt. 100 % Polyvinyl alcohol 3.0% %
Paraffin 33.5%
DCF with Inventive CPWB Microstructure-Based DCA Emulsion
TABLE-US-00007 TABLE 7 DCF Formulations Experiment No. Control 1 2
3 4 0% CPWB 2% CPWB 3.1% CPWB 4.7% CPWB 6.2% CPWB Ingredient
microstructure microstructure microstructure microstructure mic-
rostructure DCA emulsion DCA emulsion DCA emulsion DCA emulsion DCA
emulsion Preservatives 0.2 0.2 0.2 0.2 0.2 Polyether 0.1 0.1 0.1
0.1 0.1 siloxane copolymer Latex CPS 7.5 5.2 5.1 4.3 3.5 716 Water
37.9 38.1 37.6 37.3 37.0 Wax 0.0 2.0 3.1 4.7 6.2 emulsion Cellulose
0.6 0.6 0.6 0.6 0.6 ether Attagel 30 2.0 2.0 2.0 1.9 1.9 clay Mica
4K 6.3 6.3 6.3 6.2 6.2 Microwhite 36.3 36.5 36.1 35.8 35.5 100
calcium carbonate Perlite, 9.1 9.1 9.0 8.9 8.9 SilCel 43-34
Five wax emulsions including one Control emulsion were prepared.
The Control emulsion had 0% inventive emulsion comprising CPWB
microstructures. Experiment 1 had 2%; Experiment 2 had 3.1%;
Experiment 3 had 4.7%; and Experiment 4 had 6.2% wax emulsion
included in the DCF.
The CPWB microstructure based DCA emulsion that was created in the
manner described in this work is comprised of a paraffin particle
that is surrounded by polyvinyl alcohol polymer chains that are
chemically bound (via hydrogen bonding) to the surface of the
paraffin. The paraffin is therefore largely encapsulated by
polyvinyl alcohol. Stated differently, there is no substantially
exposed paraffin surface in this wax emulsion. The net effect of
this is that, when added as a component of a DCF formulation, this
wax emulsion augments the low-dust character, water-resistance, as
well as adhesion and therefore necessitates the reduction in the
formulation's overall binder content. On the other hand a wax
emulsion that had been prepared using similar components, but which
did not include any polyvinyl alcohol as an emulsion stabilizer
during the emulsion preparation stage would have had its paraffin
particles exposed. When added as a component of a DCF, this exposed
paraffin surface had a deleterious consequence on DCF adhesion,
even if polyvinyl alcohol was post-added as part of the DCF
formulation. As an example, a wax emulsion was made with no
polyvinyl alcohol as shown in Table 8.
TABLE-US-00008 TABLE 8 Wax Emulsion with No Polyvinyl Alcohol
Encapsulant Ingredient Qty. Water 61.9 Polyvinyl Alcohol 0.0
Paraffin Wax 34.5 Montan Wax 3.1 Potassium Hydroxide 0.5 (45%
solution) Total Weight 100 % Paraffin 34.5%
Adhesive properties of a DCF containing the no-PVOH paraffin wax
emulsion in Table 9 was compared against the adhesive properties of
a DCF containing a PVOH-encapsulated paraffin wax emulsion. The
total amounts of polyvinyl alcohol in each case was made equivalent
by post adding an equivalent quantity of polyvinyl alcohol to the
DCF formula into which the no-PVOH paraffin wax emulsion was to be
used. The DCF formulations evaluated are shown in Table 9.
TABLE-US-00009 TABLE 9 Adhesive Properties of Control and Inventive
DCF Ingredients 1 2 Preservatives 0.2 0.2 Latex CPS 104 4.4 4.4
Water 38.3 38.3 PVOH Encapsulated Wax Emulsion (33.5% 2.4 0.0
Paraffin) Wax Emulsion, No PVOH (34.5% Paraffin) 0.0 2.3 Cellulose
Ether 0.6 0.6 Polyvinyl Alcohol 0.0 0.07 Attagel 30 2 2 Mica 4K 6.4
6.4 Microwhite 100 Calcium Carbonate 36.5 36.5 Perlite, SilCel
43-34 9.2 9.2 Total Weight 100 100 Effective Paraffin Solids
Content (g) 0.80 0.79 Effective Polyvinyl Alcohol Content (g) 0.07
0.07 Tape Bond Adhesion % 100.0% 30.0%
In some embodiments, the DCF can provide water repellency. One
indication of water repellency is the contact angle of a water
droplet on the surface of the dried DCF. A water droplet surface
that has a contact angle of less than 90 degrees would generally be
considered hydrophilic (the smaller the contact angle the greater
the hydrophilicity). Conversely, surfaces that cause a water
droplet to have a contact angle greater than 90 degrees are
generally considered hydrophobic. Commercially available ready mix
DCF have contact angles of about zero degrees, meaning that a drop
of water placed on such a surface will rapidly spread and wet out
on the surface. Embodiments of the disclosed DCF can have a contact
angle greater than about 60, 70, 80, 90, 100, 110, 120, or 130. In
some embodiments, the DCF can have a contact angle between about 60
and 130, about 115 and 130, or about 118-120. Embodiments of the
disclosed DCF, containing a wax emulsion, can have an average
contact angle of about 98 degrees (based on an average of six
measurements), or greater than about 98 degrees, indicating a
hydrophobic surface.
In some embodiments, the contact angle can be between about 60 to
about 110 degrees, or about 60, about 70, about 80, about 90, about
100, or about 110 degrees.
In some embodiments, the contact angel can be any number selected
from the following numbers in degrees:
60, 61, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77,
78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94,
95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108,
109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,
122, 123, 124, 125, 126, 127, 128, 129, and 130.
Low-Dust Products
Embodiments of the disclosed wax emulsion can be used to form many
different dust control/water-resistant products. For example,
embodiments of the wax emulsion can be incorporated into building
materials such as asphalt (e.g., comprising a viscous liquid or
semi-solid form of petroleum), concrete (e.g., comprising aggregate
or filler, cement, water, various chemical and/or mineral
admixtures, etc.), stucco, cement (e.g., formed from or comprising
calcium carbonate, clay, gypsum, fly ash, ground granulated blast
furnace slag, lime and/or other alkalis, air entrainers, retarders,
and/or coloring agents) or other binders. In some embodiments, the
wax emulsion can be incorporated into concrete cover coat
formulations, such as those used for filling, smoothing, and/or
finishing interior concrete surfaces, drywall tape, bead embedment,
skim-coating, and texturing drywall. Further, embodiments of the
wax emulsion can be incorporated into concrete and/or cement
mixtures as a dust reducing additive. Therefore, embodiments of the
wax emulsion can be incorporated into pourable concrete and/or
cement that can be used, for example, for foundations in home
constructions. Additionally, embodiments of the wax emulsion can be
used in cinder blocks as well as other similar concrete or cement
based products. In some embodiments, a low-dust/water-resistant
building material can be formed with cement, wax emulsion, and
silicone, or siloxane, or siliconate, or fluorinated compound, or
stearate, or combinations thereof.
From the foregoing description, it will be appreciated that
inventive devices and approaches for low-dust/water resistant
products and wax emulsions have been disclosed. While several
components, techniques and aspects have been described with a
certain degree of particularity, it is manifest that many changes
can be made in the specific designs, constructions and methodology
herein above described without departing from the spirit and scope
of this disclosure.
Certain features that are described in this disclosure in the
context of separate implementations can also be implemented in
combination as well as in a single implementation. Conversely,
various features that are described in the context of a single
implementation can also be implemented in multiple implementations
separately or in any suitable subcombination. Moreover, although
features may be described above as acting in certain combinations,
one or more features from a claimed combination can, in some cases,
be excised from the combination, and the combination may be claimed
as any subcombination or variation of any subcombination.
Moreover, while methods may be depicted in the Drawings or
described in the specification in a particular order, such methods
need not be performed in the particular order shown or in
sequential order, and that all methods need not be performed, to
achieve desirable results. Other methods that are not depicted or
described can be incorporated in the example methods and processes.
For example, one or more additional methods can be performed
before, after, simultaneously, or between any of the described
methods. Further, the methods may be rearranged or reordered in
other implementations. Also, the separation of various system
components in the implementations described above should not be
understood as requiring such separation in all implementations, and
it should be understood that the described components and systems
can generally be integrated together in a single product or
packaged into multiple products. Additionally, other
implementations are within the scope of this disclosure.
Conditional language, such as "can," "could," "might," or "may,"
unless specifically stated otherwise, or otherwise understood
within the context as used, is generally intended to convey that
certain embodiments include or do not include certain features,
elements, and/or steps. Thus, such conditional language is not
generally intended to imply that features, elements, and/or steps
are in any way required for one or more embodiments.
Conjunctive language such as the phrase "at least one of X, Y, and
Z," unless specifically stated otherwise, is otherwise understood
with the context as used in general to convey that an item, term,
etc. may be either X, Y, or Z. Thus, such conjunctive language is
not generally intended to imply that certain embodiments require
the presence of at least one of X, at least one of Y, and at least
one of Z.
Language of degree used herein, such as the terms "approximately,"
"about," "generally," and "substantially" as used herein represent
a value, amount, or characteristic close to the stated value,
amount, or characteristic that still performs a desired function or
achieves a desired result. For example, the terms "approximately",
"about", "generally," and "substantially" may refer to an amount
that is within less than or equal to 10% of, within less than or
equal to 5% of, within less than or equal to 1% of, within less
than or equal to 0.1% of, and within less than or equal to 0.01% of
the stated amount.
Some embodiments have been described in connection with the
accompanying Drawings. The figures are drawn to scale, but such
scale should not be limiting, since dimensions and proportions
other than what are shown are contemplated and are within the scope
of the disclosed inventions. Distances, angles, etc. are merely
illustrative and do not necessarily bear an exact relationship to
actual dimensions and layout of the devices illustrated. Components
can be added, removed, and/or rearranged. Further, the disclosure
herein of any particular feature, aspect, method, property,
characteristic, quality, attribute, element, or the like in
connection with various embodiments can be used in all other
embodiments set forth herein. Additionally, it will be recognized
that any methods described herein may be practiced using any device
suitable for performing the recited steps.
While a number of embodiments and variations thereof have been
described in detail, other modifications and methods of using and
medical applications for the same will be apparent to those of
skill in the art. Accordingly, it should be understood that various
applications, modifications, materials, and substitutions can be
made of equivalents without departing from the unique and inventive
disclosure herein or the scope of the claims.
* * * * *