CA1041559A - Mineral wool fiber insulation products - Google Patents

Abstract

TITLE
MINERAL WOOL FIBER INSULATION PRODUCTS

ABSTRACT OF THE DISCLOSURE
Mineral wool fiber insulating compositions are provided which may be formed by deposition of a slurry of the composition upon a foraminous mandrel immersed in that slurry. Compositions of the invention are characterized by high-strength and superior processing characteristics and comprise a major portion of mineral wool fibers, a minor portion of colloidal clay, binders and about one percent by weight zinc borate. Zinc borate reduces considerable exotherms associated with conventional organic starch binding agents and also effectively flocculates slurries from which compositions of the invention are deposited.

Description

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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~041559 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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lO~lS59 ~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 -~
., 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 .. . . - .. v ~ .
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 .. '' ' _7 _ .... . . , . .~ ~

-~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 I '' ~ 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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: 10415S9 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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' .~ 1041559 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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~041SS9 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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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.
~ ~, 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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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 - 20 products are employed on a job site, it is common to grind or saw the product to custom fit an article being in~ulated. ~
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, - 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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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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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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Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A mineral wool insulating composition comprising a major portion of mineral wool fibers, a minor portion of a clay selected from a colloidal clay and mixtures of preselected colloidal clays, a starch binder in an amount of between about 1% and 4% by weight of said insulating composition, and zinc borate in an amount of between about 0.5% and 4% by weight of said insulating composition, said insulating composition having a maximum exotherm of between about 660°F to 710°F.

2. The mineral wool insulating composition as set forth in claim 1 wherein said major portion comprises an amount in excess of about 60% by weight of said insulating composi-tion and said minor portion comprises from about 10% to 25%
by weight of said insulating composition.

3. A mineral wool insulating composition as set forth in claim 1 wherein said starch binder is present in an amount of about 3% by weight of said insulating composition, said insulating composition having a density of between about 11 and 14 pounds per cubic foot.

4. The mineral wool insulating composition as set forth in claim 1 wherein said zinc borate comprises about 1%
by weight of said insulating composition.

5. The mineral wool insulating composition as set forth in claim 1 wherein said clay comprises mixtures of collidal clays and said preselected colloidal clays comprise bentonite clay and kaolinite clay.

6. The composition as set forth in claim 5 wherein said bentonite clay comprises about 2% to 10% by weight of said insulating composition and wherein said kaolinite clay comprises about 7% to 15% by weight of said composition.

7. The composition as set forth in claim 6 wherein said bentonite clay comprises about 3.5% by weight of said insulating composition and wherein said kaolinite clay comprises about 11.3% by weight of said composition.

8. The mineral wool composition as set forth in claim 1 wherein said insulating composition is formed by deposition of the components of said composition from an aqueous slurry containing about 2% to 6% by weight solids wherein said solids constitute said components upon a foraminous mandrel in contact with said slurry, said mandrel having a preselected outer surface configuration and wherein said foraminous mandrel is subjected to a vacuum whereby said solids in said slurry are drawn into contact with said mandrel surface to thereby deposit said insulating composition thereon.

9. The composition as set forth in claim 8 wherein said components further include about 0 to 1% colloidal alumina by weight of said composition and 0 to 0.06% by weight based on said clay of an organic flocculant.