Note: Descriptions are shown in the official language in which they were submitted.
104~5sg
~ACXGROVND OF THE INVENTION
1. Field of the Invention
This invention relates to mineral wool fiber insula-
tion compositions and more particularly to compo~ition~ of that
type of superior physical properties compri~ing a major portion
of mineral wool fibers and a minor portion of a colloidal min-
eral clay or mixture of ~uch clays.
2. Descri~tion of the Prior Art
Insulation products comprising compo~ite mas~es
in¢luding mineral wool fibers, clays and conventional binding
system~ such as organic starches and the like are well known
in the art. Such insulation products have in the past been ~ -
cast as a wet mass in a mold and thereafter baked to form a
dry insulation product. In United States Patent 3,968,004, -
issued on July 6, 1976, entitled "A Process Por Making A
Shaped Fibrous Article By A Vacuum Porming Process And The ~ v
Shaped Plbrous Article Made Thereby~, there is provided a
method of forming an insulation product in which an aqueous
; slurry 1B provided which includes mineral wool fibers,clays,
binding agent ~starch) and flocculating components ~uch a~ alum- -
inum oxide (alumina) and an organic flocculating agent such
as a cationic aqueous alkyl-resin composition. A slurry
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of the foregoing components is prepared having a solids
content of about 2-6 percent by weight, preferably about
3.7 percent by weight in a forming tank. A mandrel having
a preselected outer surface configuration is introduced into
contact with the slurry in the forming tank. The mandrel
has a foraminous character and is sub~ected to a vacuum
whereby solids in the forming tank slurry are drawn into
contact with the mandrel surface to thereby deposit the
mineral wool insulation composition thereupon. The mandrel
is maintained in contact with the slurry until a sufficient
desired thickness of insulation composition is deposited
upon the mandrel. Thereafter, the insulation compositi~n
bearing mandrel is withdrawn from contact with the slurry
in the forming tank, trimmed to a desired uniform exterior
shape, optionally coated with selected materials, and finally
bake-dried at an elevated temperature to provide a dried
mineral wool insulation composition having a moisture content
of less than about 1 peroent.
The foregoing process provides a superior mineral
wool insulation product having good physical characteristics
; and exoellent i~sulating properties. However, those composi-
; tions do suffer from certain disadvantages. For example, when
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~ubjected to an elevated temperature, an exotherm occure
which is believed to be due to combustion of the starch
binders employed in the process. The u~e of starch as a
binder is, however, very desirable due to its excellent
binding characteris~ics in such compositions. On the other
hand, there is a need to provide a means for reducing the
exotherm associated with the foregoing starch containing
insulation compositions. -
Accordingly, it is an object of this invention to
provide a mineral wool insulation product having a reduced -~
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exotherm when compared to other products having starch binders
incorporated therein. It is a further object of the invention
to provide a mineral wool product which is readily formable by
deposition on a foraminous member from an aqueous slurry
including the product constituents. An additional object of
this invention is to provide a mineral fiber insulation product
fonmed as described in the absence of appreciable portions of
conventional flocculants. Theee and other objects and ;~
advantages of this invention will become apparent as the
following more detailed description thereof proceed~.
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SUMMARY OF THE INVENTION
This invention provide~ improved mineral wool
insulation compositions which may be formed by deposition
from an aqueous slurry including the constituents of the
composition upon a foraminous mandrel immersed in that slur-
ry. Compo6itions of the invention comprise a major portion
of a mineral wool fiber, a minor portion of a colloidal clay
-, or mixtures of selected colloidal clays, binder and about
0.5 to 4 percent by weight zinc borate. Preferably, the
mineral wool fiber comprise3 greater than about 60 percent,
;~ and most preferably greater than about 70 percent by weight
of compositions according to the invention.
Conventional starch binders may be employed in
compositions according to the invention and are present in
amounts from about 1-4 percent by weight and preferably less
than ~bout 3 percent by weight of insulation compositions of
the invention. Colloidal alumina may also be present in an
amount up to 1 percent by weight of the composition and an
organic flocculant may be pre~ent in an amount up to 0.06
percent by weight based on the clay in the composition.
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The colloddal clays or mixtures of colloidal clays
are pre~ent in amounts of about 10-25 perceh~ by weight of
solids content of preferred insulation compositions according --
to the invention. In a most preferred instance, the colloidal
c}ays useful in compositions off the invention comprise an
admixture of bentoniteaodikholinite clays in preselected
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respective p~portions.
Additional details of the invention will become - -
apparent as the following detailed description thereof proceeds.
; 10 D1TAILED DESCRIPTION
hi Composit~ons according to the invention include
mineral wool fibers as a major portion thereof, preferably in
excess of about 60 percent by weight thereof. The mineral
wool fiber compositions useful in the invention may comprise
the various cnmmercially available mineral wool compositions
such a8 those known as Texas RocX Wool (prepared from blast
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furnace slag and silica rock), Bethlehem Steel loose or
baled, and the like. All mineral wools are essentially
fibrous materials comprising mixtures of various mineral
oxides. A typical approximate oxide analysis of a commercial
mineral wool comprises: 40% SiO2; 20% CaO; Fe2O3 and 7% A12O3
with remaining minor amDunts of oxides of magnesium, copper,
zinc, etc. As heretofore stated, the commercially available
mineral wools are generally satisfactory in compositions
according to the invention.
The mineral wool insulation composit~ons according
to the invention additionally include a minor portion of a
colloidal clay or selected admixtures of colloidal clays.
By colloidal clays iB intended those clays, usually mined
clays, which comprise naturally occurring admixtures of
kaolinite, montmorillonite and bentonite. All may be classed
as hydrous silicates and are sold in various commercial grades
and particle size ranges under varying trade designations, as
is well known by those in the industry. The colloidal clays
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~041559
or admixture of selected colloidal clays preferably compri~es
about 10% to 25~ by weight of insulation compositions accord- - -
ing to the invention. ID a most preferred instance, the
colloidal clays comprise an admixture of bentonite and kaolinite
clay~, e~pecially where said bentonite clay is present in an
amount of from about 2% to 10~ by weight and said kaolinite
clay is present in an amount of from about 7% to 15% by weight
of said insulation compositions. In copending application
Serial No. 226,391 entitled "Mineral Wool Insulation Product"
filed in lieu thereof on May 6, 1975, mineral wool insulation
compositions are provided which include the bentonite/kaolinite
clay mixtures in mineral wool insulation compositions which
demon~trate excellent physical properties and are superior ;-
from the standpoint of free (uncombined) silica in the dried
product. A most preferred composition comprises about 3.5%
bentonite clay and 11.3% by weight kaolinite clay in the dried
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~ mineral wool insulation product.
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Mineral wool insulation compositions of the invention - -
addltionally include zinc borate in an amount from about 0.5% to
4% by weight of said composition. Usually an amount of 1% to 2%
1~ ntl~factory. Tbe u~e of zirc borate reduco- the exotherz
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associated with organic starch binders in formed mineral wool
insulation products according to the invention. Accordingly,
insulation compositions of the invention exhibit a substan-
tially reduced exotherm when exposed to elevated temperatures.
In addition, it has been found that, surprisingly, use of zinc
borate in aqueous ~lurries including the composition consti-
tuents, eliminates or reduces the need for inorganic and
organic flocculants in those slurries for forming most preferred
compositions according to the invention. In such slurries total
solids usually comprise about 2% to 6% by weight, typically 3.7%
by weight, as heretofore described with reference to copending
application Serial No. 226,391 filed on May 6, 1975 and entitled
~Mineral Wool Insulation Product". With the use of zinc borate
according to the invention it has been found that colloidal
alumina may be reduced or eliminated from a slurry batch with-
out significantly effecting the strength of dried mineral wool
in~ulation product. It has further been found that the amount
- of organic flocculant may be reduced by a factor of one-half
or more without significantly effecting the strength of dried
product.
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The invention will be further understood by
reference to the following specific examples of certain
illustrative and preferred embodiments thereof. In the
Examples, all percentages are by weight unless otherwise
indicated.
EXAMPLE I
An aqueous slurry was formed which included the
following confitituents:
Material Percent
Xentucky Tenn M & D Clay 20.3
- "M & D Clay iB a naturally
occurring mixture of
A detailed description of
M & D Clay iB found in
U. S. Patent 3,470,062. ~
Starch 2.0 -
Colloidal Alumina 0,8
Zinc ~orate 1.0
Texas Rockwool ~Mineral Wool) 76.0
100.1
In addition to the foregoing, 0.025 percent (based
on clay) of an organic flocculant sold commercially by Hercules
Co. under the trademark Reten. That amount constituted less
"
than one-half the amount normally employed without zinc borate.
Nevertheless, good products were obtained without excessive
foaming processing problems. ~
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From the foregoing batch, several mineral wool
insulation compositions were formed in the manner ~et forth
hereinabove with respect to United States Patent 3,968,004,
wherein slurry or batch constituents are deposited in a
foraminous mandrel in contact with the slurry. The following
Table 1 illustrates various physical properties of the dried
mineral wool insulation products thus formed.
Table 1 (Example 1)
Maximum Exotherm
Test No.DensitY, pcf Temperature F.
811 12.9 660
817 13.2 670
818 13.4 710
819 13.2 710
In determining the "Maximum Exotherm TemperatureU of
~able 1, a slab of dried product wa~ laid upon a hot plate
surface having an external face temperature of 800F. A thermo-
couple was placed in the dried sample one-inch thickne~s away
from the hot-plate ~urface. Temperatures were recorded with
time pa~sing to determine the maximum temperature occurring in
the dried sample. It wa~ known that dried samples without zinc
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1041559
borate, but otherwise identical to those compositions of
Example 1, exhibit an exotherm in excess of 1,000F. and
sometimes in excess of 1,100F. The samples of Example 1
exhibit maximum exotherms of 660F. - 710F. and the ability - -
of zinc borate to reduc~ the undesired insulation composition
exotherm was clearly demonstrated.
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Example 2 -
Mineral wool insulhting compositions containing
zinc borate were formed in the manner of Example 1 wherein
the only substantial variable was colloidal alumina. In one
instance colloidal alumina was eliminated from the composition
and in the other it was present. The tests were made to
demonstrate the unexpected ability of zinc borate to function
as mineral fiber/clay binder and flocculant~ The product
r composition employed and test data from the experiment are
shown in Table II, hereafter.
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1041559
The foregoing example clearly indicates that zinc
borate does indeed perform well in replacing colloidal alumina ~ ~
as a flocculant in binding clay and fibers. The physical ~ -
strengths, both flex and compressive, are plainly comparable.
Thus zinc borate was demonstrated to have an unexpected duality
function, i.e. to reduce an unwanted exotherm and to aid in
binding clay and fibers to provide a dried product having good
physical characteristics.
It may also be noted here that Example 2 is illu- -
strative of the use of kaolinite/bentonite clay mixtures in
accordance with a preferred instance of mineral wool insula-
tion compo~itions useful in the invention.
~- In Table III hereafter there are listed several
representative mineral wool insulation compositions prepared '~7',' ''
as hereinabove described. The Table additionally lists
- several phy~ical characteristics of each of the compositions,
and also includes an indication of the "Free Silica" in a
dried product. Free silica indicates a quantity of uncombined
crystalline silica in the composition. When dried insulation
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or saw the product to custom fit an article being in~ulated. ~
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1041559
- Where that is the case t~e"freensilica i8 released into the
- atmosphere thereby creating a health-hazard ~silicosis-inducing)
to those in the~lrea.
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Test &
No. Fibers Type Clay
Georgia Kaolin Co. % Type
859 75.2 #6 Tile Clay Clay Bentonite
Georgia Kaolin Co. IMC
864 75.8 #6 Tile Clay 18.0 SDG-220
Huber Co. IMC
863 75.2 D-6 Kaolin 17.2 SDG-220
Georgia Kaolin Co. IMC
886 73.7 #6 Tile Clay 17.0 SDG-220
Georgia Kaolin Co. IMC
885 73.7 - #6 Tile Clay 17.5 SDG-220
Georgia Kaolin Co. IMC
846 75.2 #6 Tile Clay 16.5 SDG-220
Huber Co. INC
856 75.2 K-6 Daolin 12.5 BH-200
Georgia Kaolin Co. IMC
852 75.2 #6 Tile Clay 11.3 BH-200
Georgia Kaolin Co. IMC -
853 75.2 #6 Tile Clay 11.3 BH-200
Georgia Kaolin Co.
% Flocculant = % of clay in batch 11.3 K-4
; 2 % Free silica in total batch
3 IMC is the International Nineral Company
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1041559
According to the provisions of the patent statutes,
I have explained the principle, preferred construction and mode
of operation of my invention and have illustrated and described
what I now consider to Depresent its best embodiment~.
: However, it should be understood th~t, within the scope of
the appended claims, the invention may be practiced otherwise
than as specifically illustrated and described.
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