US2014065A - Insulating building and sound absorbing material - Google Patents

Description

106. COMPOSITIONS,

comma on PLASTIC pa r-ED V'VSTATES "Cross Reference PATENT, OFFICE,

INSULATING BUILDING AND soUND Products, 'Inc., Chicago, 111., a corporation of Illinois N Drawing. Application January .10, 1929,

'Serial No. 331,716

Claims. (01(106-48) This invention has todo with materials used for temperature insulation, as for example for lining or building the walls of heat treating furnaces, where high temperatures are used, in which 5 case the insulating material must be highly refractory, or for insulating buildings, refrigerators, "refrigerator cars and like structures, where a purposeof the insulation is either to maintain uniformity of temperature either by preventing the transfer of heat or sound through the wall in either direction. 3

This generally recognized that the efficiency-of insulating materials of the class referred to, so far asheat conductivity 'is concerned, depends to a great extent upon the number, size and disposition of the air spaces or voids present therein, although more recent investigation indicates that the physical condition =01 the insulating material termed surface effect may be of equal or greater importance as affecting the relative insulating values, since it seems to bear a direct relation to the absorption of heat or sound by a given body. For example, a number of highly polished surfaces greatly impede the flow of heat, and if such 2 surfaces differentiate with respect to their heat absorbing characteristics as far as possible from the theoretical black body", or perfect h'eat absorbent, the resistance to heat flow is further increased, j I It is also found that where the surface of a given body is formed of a large number of smallsound absorbing and reflecting surfaces at infinitely varying angles toeach other, sound waves striking the surface are broken up, and the sound absorbing quality of the body is increased.

Refractory materials having relatively high insulating qualities, for limiting the 'heat losses through the walls of heat treating'iurnaces, such as brick, blocks of various shapes, and plasticor semi-plastic masses for molding into space insulation, have heretofore been limited to such natural products as kieselguhr (iniusorial earth) or compounds obtained "by some treatmentmf-such materials, or by the mixture of refractory clays with combustible materials that are burned out during the firing operation, but such insulating materials are expensive, heavy, have only a low resistance :to the transier of heat and not well :adapted for use for low temperature work. Insulating materials for low temperature work in connection with buildingarefrigelators, &c., and for sound proofing, have been made from many natural and processed materials having widely varying characteristics, such as vegetable and mineral J ib r. Vegetable fibers, if used for such purpose,

require treatment to prevent bacterial action and ,for fireproofing, and mineral fibers have other -characteristics that seriously impair their value .andefiiciency for insulating purposes. For examplaasbestos fibers areexpensive and are relative- 5 -=l-y heavy, and so-calle'd rock wools are extremely fragile, and tend to break into fine short glassy fragments which pack intorather highdensities when placed .in walls or likesituations, and are extremely unpleasant if not dangerous to handle, .sincethe sharp glassy fibersirritate the skin .and inflame the eyes of workmen.

The packing and resulting higher density of rock wool insulation reduces its insulating value, and the difiiculties in handling, including its failure to flow freely, prevent its wide useas a wall .insulator-forexisting buildings. The heat insulatingqualities of mineral woolsare also impaired by the fact that the nature of the material permitsthe formation of minute air currents and the 20 transfer of heat by convection.

1t isan object of my present invention, to provide a new and improved insulating material hav- .ing characteristics such as to-make it suitable for a-wide variety of uses, and which will not have the objectionable qualities found in prior materials tor the purpose as above pointed out.

Another object of my invention is to provide amaterial which maybe used in the form of small separate particles in bulk, adapted to be filled into hollow walls, and which may also be readily moulded or otherwise formed into building tiles, bricks, or-other units of-definite shapes and sizes.

Another-objectof my invention is to provide a new and improved material of the above described 5 character and which will be highly suitable for *use for sound proofing purposes. Y 7 The invention also relates to the production of a new and improved material of the above described character which will be both fire proof 9 and vermin proof. 1 Other objects of-the invention will appear from the following description and the accompanying claims.

Molten silicates of calcium, aluminum, and other common elements, obtained by melting limestone, sandstone and/or aluminiferous clays and shales, 'whencooled rapidly by various methods, produce low density masses of widely varying characteristics, depending on the means and rapidly of cooling. When the cooling medium is air or steam at high pressure the resulting mass is what is commonly termed rock wool, and as above mentioned has a fibrous structure of a glassy character which is objectionable for use Examine;

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as an insulating material for the reason stated. When, however, the cooling medium is water supplied under pressure, and in such quantities that the water adhering to the slag is at least momentarily converted into steam, the resultant mass takes on a highly cellular structure similar to that of pumice stone, which is free from the objectionable characteristics of rock wool. This cellular material may well be termed rock sponge, although it lacks the characteristic capillary structure of natural sponge, and, therefore, is nonabsorbent except superficially.

If too much water is used, the cooling of the molten silicate occurs too rapidly, and the material hardens before the minute bubbles have time to form. The material breaks up into a slightly porous sand, which is known as granulated slag. This material has a considerably higher specific gravity than water, and of course will not float in water.

It may be stated that molten silicates in the form of slag from blast furnaces have been treated with copius quantities of water, so as to form granulated slag. This was done for the purpose of breaking up the slag into a form in which it might readily be conveyed away from the blast furnace, and it was of course not desirable to increase the bulk of the material by puffing it up into a spongy mass which would float in water. It is possible that such granulated slag contained small percentages of rock sponge, but this was considered objectionable, as it increased the bulk of the material to be removed.

The term rock sponge as used in this specification and the appended claims is intended to mean a highly porous material which is produced by cooling the molten slags of the character herein described with a stream of water of high pressure but small volume. The volume ,of water being reduced to such a point that substantially all of it is turned into steam as it contacts with the slag. This term is intended to include only material of such high porosity as to be at least temporarily floatable in water and .does not include what is known as granulated slag or artificial sand which have previously been produced by applying copious quantities of water to the molten slag.

Rock sponge may be produced by melting raw rock, sand and shale in suitable furnaces and causing a stream of water at considerable pressure, usually about thirty pounds per square inch or more, and at normal temperature, say sixty to seventy degrees F., to impinge on a stream of the molten material as it issues from the furnace. The exact pressures and temperatures, however, are not so important as the proper regulation of the quantity and velocity at the point where the stream of water strikes the stream of molten slag. A convenient and economical source of supply is found in connection with blast and other metallurgical furnace operations, since rock sponge may be produced in large volume at negligible expense by rapidly cooling a stream of molten slag from the furnace by impinging thereagainst a stream of water under considerable pressure. However, the quality and purity of the product are more easily controlled by using raw materials which have not been mixed with the iron and other materials found in the blast furnace. The density of the resultant product is controlled to a marked degree by suitable adjustment of the temperature and pressure of the water, or in other words, by the rate and conditions provided for cooling the slag. Ordinarily, the temperature and pressure above indicated give very satisfactory results, but they may be varied considerably without modifying the cellular character or density of the rock sponge produced to such an extent as to render it unsuitable for insulating purposes. The proper 5 temperatures, pressures and volume may readily be determined by the operator, bearing in mind the fact that the greatest amount of rock sponge will be produced with substantially that volume of water which will be at least temporarily converted into steam, and also the fact that the higher the velocity, the smaller will be the fragments into which the rock sponge will be broken. Increasing the temperature of the water and/or lowering its pressure tends to increase the percentage of rock sponge produced, and vice versa, and in like manner the size of the masses of rock sponge formed may be varied through a comparatively wide range, from small masses approximately the size of popcorn to very much larger masses. The product is of extremely low density, having a maximum number of cells that vary more or less in size throughout the mass, all the cells having Walls the surfaces of which are polished or glassy, so that the material combines the insulating properties of a multiplicity of dead air spaces or voids, and the polished surfaces, or surface effect characteristic, which differentiate it to a maximum degree from the theoretical black body which absorbs heat at the maximum rate.

In order that rock sponge may be employed for insulating purposes without materially impairing its insulating value, it is necessary that the raw material be divided, without crushing, into sizes suitable for the use to which it is to be put, since crushing to a large extent destroys its cellular structure, and, therefore, greatly reduces such insulating value. To avoid such crushing, subdivision of the rock sponge may be accomplished by slicing the raw material, passing it through cracking rolls, or forcing it through coarse but sharp edged screen apertures of suitable size to reduce the material to comparatively small particles having the desired dimensions. Any other i means suitable for reducing the material to particles of the desired size with a minimum amount of reduction of cellular structure may be employed.

The material produced as above described may be employed for a great variety of purposes, either with or without further treatment. For example, it may be used either as loose filling for hollow walls, for the manufacture of refractory materials, or for other purposes such as fireproof partitions or walls, floors, roofing materials, &c.

When the subdivided particles of rock sponge are to be made into an aggregate, it is desirable that properly selected sizes be assembled so that the voids between the larger pieces may be substantially filled by smaller pieces of similar cellular structure. To this end the subdivided stock is passed over numbered screens so that suitable portions may be available subsequently to make up any desired aggregate, whether for loose filling 5 of hollow walls, or for such other uses as it may be desired to make of it.

If the subdivided particles of rock sponge be first coated with a film of cement, or some other form of bonding agent, which is allowed to dry or set prior to the incorporation of the aggregate into insulating products, the mechanical strength of the particles is greatly increased without materially changing the weight or density of the aggregate, since owing to its non-absorbent 106. cowosmous, Cross Reference Examiner COATlNG R PLASTlC for many insulating purposes.

quality the bonding agent is not absorbed into the cellular mass of each particle, but remains as a light superficial coating. Such preliminary treatment also tends to prevent further breaking down of the size of the particles in the aggregate during further processing, thus limiting the production-of fines and consequent reduction of the insulating value of the material. Precoating of the particles also facilitates the cementation of the aggregate into a firm mass by proper admixture with aminimum additional amount of such bonding agent.

When the bonding agent employed is gypsum plaster, which, as above indicated may properly be applied to the particles before and/or after the formation of the material into an aggregate, the resulting mass is extremely light in weight,'highly resistant to the fiow of heat, and amply strong If a portion of paper pulp or other comminuted fibers be added to the binder, or incorporated in the aggregate, an insulating material is produced which has very high resistance to the fiow of heat, is entirely fireproof, has very low density, is vermin and bacteria proof, and possesses the quality of eifectuallysealing the insulating mass against the flow of air or other gases through the same, thus adding to the excellent insulating value the property of sealing against infiltration of air when the material is used for wall insulation for houses, cooled spaces and similar low temperature applications.

*When'an aggregate consisting of graduated sizes of rock sponge so apportioned as to substantially fill the voids between the larger particles with smaller like particles is poured into hollow wall spaces for insulating purposes, the mass thus formed tends to set or cake into the space available without packing or increased density toward the bottom of such wall spaces, yet flows freely during the filling operation. When the above described aggregate also contains a small percentage of paper pulp or other fibrous material, the above described setting or caking condition is accentuated, and the insulator thus formed is given the added features of lower density with complete sealing against flow of air or gases throughout the same. When gypsum plaster is added to either of the above described aggregates, and provision is made to hydrate the gypsum at the time the material is poured into insulating space, the caking or setting of the mass is complete and a permanently caked insulatoris thus formed which possesses practically every conceivable advantage in heat or cold insulation, i. e., low cost, light weight, permanent character, proof against fire, vermin, bacteria and chemical change, an ideal seal against in filtration as well as radiation, and ease of application to any hollow space either in old or new construction.

The above described insulators may be applied to space insulation by pouring from a container or may be carried into the space to be insulated by'means of a large hose, being forced through the same by means of a stream of air under suitable pressure, or by a vacuum.

When Portland cement is used as the bonding agent for aggregates of rock sponge, the blocks formed are extremely strong, light in weight, and possess about five times the resistance to heat fiow of ordinary concrete. Such blocks or masses are valuable for high temperature insulation where considerable mechanical strength is needed, and where the maximum temperature does not exceed one thousand degrees F. Such insulating masses may be molded in place as linings for furnace doors, heat protection for concrete foundations tor high temperature furnaces, and for many other applications within the natural limits of temperature and strength prescribed by the 5 nature of the bonding material.

When the bonding agent is plastic or common building brick clay, the blocks may be burned after the manner of burning brick, and after burning have properties of strength suflicient for up all building purposes, are impervious to moisture, -non-absorbent, and have approximately six times the resistance to heat flow of ordinary brick. Such blocks, brick, tile, &c., may be surface coated with suitable enamels .or glazes, and reburned, 15 thus forming finishing or outer wall brick or blocks. Building blocks thus formed have high insulating value and greatly reduce the weight imposed upon foundations, steel structures, &c. Roofing tiles may be molded from the above -dc- 28 scribed materials, and suitably coated and returned to secure desired colors and imperviousness to moisture, and a roof thus finished will reduce the heat losses by approximately one half and provide a much lighter dead load to be sup BS ported by trusses and walls.

Roofing and wall slabs may be formed by the use of gypsum bond with rock sponge aggregate. Such slabs may be re'enforced with wire mesh so as to cover large spans, as compared with '89 other roofing blocks, and provide extremely strong light roofs having low heat loss through the same. They may also be made to interlock, the surface being first rendered impervious to "moisture by suitable coatings of plastic or air 85 setting cements, or finished roofs may be coated in the usual way with felted roofing sheets, tar and gravel, 810. Wall slabs may be similarly molded to standard dimensions for use in lieu of gypsum plaster, hollow tile, or as fillers for frame 40 structures. When thus applied rock sponge aggregates provide high insulating value, low weight, low cost, exclusion of sound, and may be used as direct plaster base. The material may also be molded into surface tile for finishing walls, 45 ceilings, etc., and such tiles are not only highly efiicient for the absorption of sound and insulation of heat, but they are highly decorative. It may be added that their decorative qualities may be enhanced, without greatly affecting the sound 50 absorbing or heat insulating qualities, by coating the outer surfaces with lacquer. Due to the fact that the tile structure is only superficially absorptive, the cellular structure is unimpaired, and only a comparatively small quantity of lacquer or paint is necessary.

When the bonding agent is refractory, or so called fire cement, either air setting or set by burning, the blocks thus formed become highly refractory while retaining their natural property of high resistance to the flow of heat. Precoating of the particles of the aggregate increases the mechanical strength and the softening point under heat of the finished product. Such blocks have great mechanical strength against crushing, and will withstand temperatures up to twentyeight hundred degrees F. The application of such insulating blocks between the shells of heat treating furnaces and the firebrick lining, limits the heat losses to a negligible amount. Such blocks have very low coefiioients of conductivity, yet unlike any natural heat resisting insulator, have sufficient mechanical strength to carry all the necessary furnace loads, either between foundations and firebrick, or between buck stays and firebrick.

Such blocks when used over arches act as an excellent insulator without adding seriously to the dead load. Insulating refractory brick or blocks produced as described have substantially the same coeflicient of expansion as ordinary firebrick, and hence reduce the tendency to leave open cracks and fissures after heating and cooling.

Where, as sometimes occurs, the rock sponge contains traces of acids or alkalis which may be undesirable in the ultimate insulating material, or aggregate, if the further processing of such aggregate does not involve sufficient heat to drive off all objectionable compounds, such compounds may be neutralized by the addition of small amounts of lime or spar as may be indicated to correct the acid or alkaline condition.

So far as I am aware, the use of. the material hereinbefore described as rock sponge for insulating purposes, and its preparation for such use according to the method described, are new in the art, and the claims hereinaftermade are, therefore, intended to cover the same generically as well as specifically. It is to be understood that the term rock sponge as used in the claims is employed to designate the highly cellular material of low density derived from molten slag, or equivalent material, such as molten silicates of calcium, aluminum and other common elements obtained by melting limestone, sandstone, and/or aluminiferous clays and shales, by cooling the molten mass rapidly by means of a stream of water under pressure impinged thereon.

The term rock sponge is not intended to include the material known as granulated slag or artificial sand which are somewhat cellular in structure, but which have a comparatively high density, and are not floatable in water.

It should be understood that I do not wish to be limited to the use of a material entirely free from non-fioatable ingredients, as the addition of any percentage of rock sponge to an aggregate of granulated slag produces an improvement corresponding to the percentage of rock sponge added, and is within the purview oi my invention.

I claim:

1. An insulating material consisting of small cellular masses of rock sponge mixed with plastic material to form blocks and burned.

2. An insulating material consisting of small cellular masses of rock sponge mixed with plastic material to form blocks and burned, the burned blocks being coated and reburned to form an impervious finish.

3. A material consisting of small cellular masses of rock sponge mixed with plastic material and formed into blocks, the blocks being first treated to harden the plastic, and then coated and burned to form an impervious finish.

4. An insulating material consisting of small cellular masses of rock sponge bonded together to form an aggregate mass, reenforced with wire mesh and having a. coating impervious to moisture.

5. A material consisting of small cellular masses of rock sponge bonded together to form an aggregate, having reinforcing material embedded in the aggregate, and having a coating impervious to moisture.

WILLIAM T. DEAN.