US2357042A - Method of manufacturing felted mineral wool products - Google Patents

Description

Aug, 29, 1944, H. 1'. cos s ETAL METHOD OF MANUFACTURING FELTED MINERAL WOOL PRODUCTS Filed April 24, 1941 INVENTOR Patented Aug. I 29, 1944 METHOD OF MANUFACTURING FELTED MINERAL WOOL PRODUCTS Harold'T. Coss, Somerville, Louis A. Hawthorne, Hillside, and Joseph H. Zettel, Somerville, N. J.,

.assignors to Johns-Manville Corporation, New

York, N. Y., a'corporation of New York Application April 24, 1941, SeriaINOL 390,128

11 Claims. (Cl. 154.28)

The present invention is directed to a dry procass for the manufacture of mineral wool thermal insulating p iQducts of relatively high density and having the desirable properties of insulating material sold und'er the registered trade-mark Rock Cork. It will be understood that the term mineral wool is employed herein in a generic sense to denotefibres formed from rock, slag, glass, and other conventional raw materials andfmixt'ures thereof.

In the manufacture of Rock Cori; in accordance with the procedureheretofore commercially followed, a suitable rawfmineral wool forming material is'm elted and shredded by means of a high pressure steam jet into a multiplicity'of fibres, which are collected in a blow chamber. The fibres are mixed with a water suspension of a binder,-

comprising, for example, asphalt intermixed with paper or woody p lp in such a manner that the asphalt adheres to the pulp particles-in the suspension. The mixture is then dischargedinto a suitable form, the water drained off, and the formation and which exhibits improved insulating and structural characteristics.

A further object of the invention in one form thereof is the provision'of a product of the type referred to above, and method of making the same, including an integrated surface coating.

Our invention will be more fully understood and Y further objects and advantages thereof will become apparent whenreference is made to the more detailed description thereof which is to follow and to the accompanying drawing, in which: Fig; 1 is a diagrammatic elevational view of a portion of an apparatus employed in the method ofthe instant invention;

Fig. 1a is a continuation of the apparatus dis- I closed in Fig. 1; and

Fig. 2 is a'diagrammatic sectional view taken through an insulating product made in accordance with the invention.

Referring now to the drawings, and-particu larly to Figs. 1 and hi, there is diagrammatically material is, thenpressed into the desired shape a and dried; Y

The aboveknown method, though producing 'a serviceable .and meritorious product, has presented certain disadvantages, particularly in that it is relatively slow and expensive, due to the multiplicity of .operations involved.- Also, certain ofthese operationsv produce a mashing or breaking of the'fibres, increasing the density and weight of the product to an undesirable extent, and decreasing its insulating emciency. Furthermore,

the heterogeneous arrangement of the fibres reduces'the insulating properties of the product,

the necessity of the molding step results in a surface crust which must be removed with result-'- organic material in the binder reduces the resis'tance of the product to combustion.

The instant invention has, as an object, the

provisionof -a method for the manufacture of a product having the desirable characteristics of the present Rock Cork but which overcomes the above-noted disadvantages and in which the operation is continuous from the formationof the fibres to thefinal packing of the product.

More particularly, an object of the instant invention is the provision of a method in which a continuous felt of'mineral wool fibres containing binders disseminated substantially uniformly therethrough is subjected to treatments to form a substantially homogeneous compressed block of a certain thickness, which is resistant to deshown an apparatus suitable for carrying out the method of the invention. Conventional portions of the apparatus are not shown in detail as they may take different forms. The apparatus generally comprises a melting furnace III, which may bea cupola, tank furnace, or the like, of any conventional design. Molten slag, rock, or mixtures thereof, or other conventional raw materials melted in furnace l0, issues therefrom in the form of a stream through orifice I2 and falls into the path of a steam jet I4, which shreds it .ant loss of materiaL- and the large amount of intoa great multiplicity of extremely fine fibres which are carried by the force of the steam Jet and in gaseous suspension into blow chamber I.

A binder is forced into the suspension of the fibres by suitable means, which preferably comprises an atomizing binder jet, as diagrammatically illustrated at l8. The binder is added in proportions of, say, between 10 and 30% of the weight of the fibres, preferably between 18 and 24%. The mineral wool fibres and the minute binder particles, in gaseous suspension in the blow chamber, settle in intermingledrelationship on the floor thereof.

' Binders suitable for use in the instant invention may comprise a multiplicity of different specific formulae, all of which, however, must meet certain requirements. Thus, the binder must be sufiiciently fluid to permit atomization and distribution of the same on the fibres; its viscosity must not increase excessively when the binder is stored at a high temperature for a reasonable period, say, from 8 to 12 hours; when applied to the fibres and solidified it must'be hard and preferably tough, although some degree of brittleness is permissible; and it must not be sufliciently combustible to readily'ignite in the collecting chamber. It may be stated that preferably the ing units or introducing heated air into the blow chamber.

In accordance with our present invention, the warmblanket ispassed .a's' by'a' transfer conveyor 38 from the oven 34'ordirectly from the blow chamber, if the binder is plasticized therein, to a combined surface heating, compressing.

"reference character 40.

tailings, (2) comprising gilsonite fluidified with a pressure still residue asphalt, and (3) compris-, ing a thermoplastic resin. The binders preferably include a suitable proportion of afireproofing ingredient, such as a chlorinated aromatic or cyclic hydrocarbon with a minimum chlorine content of 45%. For the sake of brevity, this material and equivalents are hereinafter referred to as chlorinated compounds.

The blow chamber I6, which receives the suspension of fibres and binder, has a bottom wall or floor comprising a continuously moving endless belt or conveyor 20 traveling in the direction indicated by the arrow. As previously mentioned, the fibres settle in felted relationship on the conveyor with the binder particles disseminated substantially uniformly throughout the felt.

The felted mass of fibres is carried from the blow chamber by conveyor 20 and preferably compacted to some extent by press roll 24 located at the exit end of the blow chamber to form a relatively thick blanket 23. Preferably, the rate of movement of conveyor 20 is correlated to the rate of deposition of. the fibres to insure uniformity in density of the product as by means of a weighing scale 29 over which the felt passes. The weighing scale is operatively' connected to the drive of conveyor 20 by any suitable means (not shown) whereby increase in the weight of the blanket increases the speed of movement of the accomplished by a warming oven 34, including foraminous conveyor belts 28 which carry the felt through the oven, the belts being driven by suitthe conveyor 20. The upper conveyor belt 'is suitably made vertically adjustable by any concally illustrated at 32, and in the operation of the device the belts are so spaced that the blanket is only slightly compressed as it passes therebetween. Air at a temperature, say, between 200-300 F., depending upon the melting point of the particular binder employed, is circulated from any suitable air heating means, such as furnace 35, through ducts 36 opening into the oven below the upper reach of the. lower conveyor 28, the heated air being forced through the conveyors and the blanket held therebetween.

The conveyors prevent any objectionable displacement of the fibres by the action of the moving] air.

Alternatively, the plasticizing of the binder may take place in the blow chamber l6. Depending upon the particular type of blow chamber employed, the residualheat in the fibres may be sufficient for this purpose, or if this is not the case, the tempsratm-e of the blanket may be raised to that 1". ecegscry as by providing heat- I ventional mechanism, such as that diagrammati- Y and cooling device, indicated generally by the In its preferred form, this device comprises endless belts 42 mounted for travel in the directions indicated by the arrows around-drums 44 and 46. As indicated inthe drawings, the belts 40 are made up of a plurality of relatively rigid, hingedly connectedfiat plates or flights 48 reinforced against yielding during the compressing operation as by flanges 50. The flights are perforated to permit the passage of cooling air therethrough. It has been found that the provision of A," holes on /2" centers is desirable. However, some considerable variation in open area of the flights may be employed, as will be understood. The edges of the adjacent reaches of the belts are supported on suitable tracks provided by beams or other supporting means 52 to maintain them in parallel relationship throughout their length. The upper belt is arranged for adjustment relative to the lower belt by any conventional rais ing and lowering device, such as indicated at 54.

The flat plates or flights making up belts 42 are heated as they pass around drums 44 by suitable means, such as gas jets, or the like, 50. The

heating means is adjusted to'raise the temperclosing the greater proportion of the lengths o1v the belts. Cooling air is drawn through the perforated flights and the blanket held therebetween by means of blower 62,. and ducts 84 'and 66 connecting chamber 60 with the blower and a source of cool air, respectively. The air may simply and preferably be drawn from the room, but, if desired, pre-cooled "air may be supplied, particularlyin hot summer weather. In lieu of air cooling, water cooling or other cooling methods may be employed if desired, air cooling, however, being preferred. I

Inthe operation of the method described above for the production of materials, say, of 2-inci: finished thickness, a felted blanket, which may he, say, 12 inches in thickness as it leaves the blow chamber and contain a binder of any of the types previously referred to in 'a proportion between 10 and 30% of the weight the fibres, is warmed to a temperature, say, of 220250 F. in warming oven 34 or in the blow chamber 10 to soften or plasticiz'e the binder. The blanket is carried by transfer conveyor 38 from the warming oven to belts 42, the adjacent flights of which are adjusted a distance apart substantially equal to the desired final thickness of the felted product. The blanket is compressed to this thickness by the belts as it enters therebetween, and, at the same time, its surfaces are brought to a relatively high temperature and the binder at and adjacent the surfaces into a fluid state by the heated plates or flights 48 during the interval between the first contact of the belts with the blanket and entry into cooling chamber 00. As the blanket passes through chamber 60, cooling air is circulated therethrough by means of fan 62 and its associated duct structure. The

ber 60 are proportioned to remove a predominant proportion of the heat in the blanket to solidify the binder in and at the surfaces thereof whereby the blanket retains its compressed state and a relatively smooth finish as it passes from between belts 42. At the completion of this stage of the operations, the blanket may be passed directly to any suitable slitting and cutting devices to divide the same into units of the desired dimensions for commercial use.

In some instances it is desirable to provide the blanket with a stronger and more dense surface structure to improve the handling properties and reduce the moisture absorptiveness of the finished product. For this purpose a unit is located to receive the blanket. The unit includes means 10,

selves to one skilledin the art, all falling within the scope of the invention as defined by the sub- I joined claims.

such as pipes, connected with any suitable source of a fireproofing ingredient, such as a chlorinated compound of the type previously referred to.

The pipes are connected to sprayheads or other suitable applicator means 12 whereby the liquid, powdered or molten coating material is applied to the surfaces of the blanket, which then passes between a surface heating means 14 preferably comprising rollers l6, the surfaces of which are subjected to the action of gas jets, or the like, 18. The surface heating means raises the. sur face temperature of the. blanket to substantially above the melting point of the applied coating material, as well as that of the originally included binder. The applied coating, in fluid condition due to the heating step, flows over the surfaces to form a thin coating of liquid, which penetrates somewhat into the blanket and fuses with the binder whereby, upon cooling, the coatings are substantially integrally united to the I blanket.

I blanket passes from the surface heating means directly between belts 80 where it is cooled sufficiently to solidify the fluid coating layer. The blanket is then divided into blocks of the desired dimensions as previously described. I

In the products made as described above and either with or without the final coating, the fibres lie in planes substantially parallel to the major surfaces, due tothe manner of felting, and this parallelism is accentuated by the compressing step; The products not only exhibit increased insulating efiiciency as compared to those in which the fibres are in a heterogeneous arrangement, but also the modulus of rupture is much higher. Particularly where the final coating step is mployed, the product has improved handling properties, its tendency to absorb moisture is reduced, and its surfaces are resistant todeformation. Notwithstanding the relatively large amount of binder originally employed and that added in the final coating step, the product is relatively resistant to combustion due to the inclusion of the fireproofing ingredient.

Having thus describedour invention in rather full detail, it will be understood that these details need not be strictly adhered to, butthat various changes and modifications will suggest them- What we claim is:

1. In the method comprising forming a felt from mineral wool fibres and a thermoplastic binder, the steps comprising heating the felt to soften the binder, surface heating the felt, compressing the felt to a uniform predetermined thickness, and cooling the felt while the same is maintained under said compression, applying a coating material to the surfaces of the felt, heating said surfaces above the melting temperature of said coating, and chilling th surfaces of the felt to set the coating material thereon.

2. The method comprising forming a felt from an air suspension of mineral wool fibres and a thermoplastic binder with the binder disseminated throughout the felt and in a proportion of the order of 10 to 30% by weight of the fibres, plasticizing the binder in the felt, compressing and simultaneously cooling the felt to set the binder, applying a thermoplastic coating material to the surfaces of the felt, surface heating the felt above the melting point of said coating material, and chilling the felt surfaces to set said coating material.

3. The method comprising forming a felt from an air suspension of mineral wool fibres and a thermoplastic binder with the binder disseminated throughout the felt and in a proportion of the order of 10 to 30% by weight of the fibres, plasticizing the binder in the felt, surface heating th felt, compressing the felt to substantially its final thickness and cooling the same while the felt is under said compression, applying a thermoplastic coating material to the felt surfaces, raising the felt surfaces to a temperature above the melt point of said coating material and binder, and chilling the felt surfaces to set said coating material and binder adjacent said surfaces.

4. In the method comprising forming a felt from mineral wool fibres and a thermoplastic binder, the improvement comprising heating the felt to soften the binder, compressing the felt to substantially its finished thickness and simultaneously cooling the felt, applying a powdered thermoplastic coating material to the surfaces of the felt, heating the felt surfaces to a temperature above the melting point of said coating material, and subjecting the felt surfaces to a cooling action to set said coating material.

5. The method comprising forming a felt from. an air suspension of mineral wool fibres and a thermoplastic binder present in a proportion of the order of 10 to 30% by weight of the fibres,

warming the felt by the circulation of heated air therethrough while maintaining the felt against disarrangement of the fibres therein, applying surface heat to the felt, compressing the felt to a uniform predetermined thickness, and cooling the felt while undercompression by the circulation of air therethrough, applying a thermoplastic coating material to the surface of the felt, surface heating the felt to a temperature above the melt point of the coating material, and chilling the felt surfaces to set the coating material.

6. A continuous method of manufacture of felted mineral wool products comprising forming an air suspension of newly formed mineral wool fibres and a binder present in a proportion of the order of 10 to 30% by weight of the fibres, warming the felt to a temperature of from 200- 350 F. to plasticize the binder, heating the surfaces of the felt to a temperature of from. 300- 500 F., compressing the felt to substantially its finished thickness, and cooling the felt to a temperature below the melting point of the binder while maintained under said compression, applying a thermoplastic coating material to the surface of the felt, surface heating the felt to a perature of from 300-500 F., compressing the felt to substantially its finished thickness, and cooling the felt by the circulation of air therethrough while maintaining the felt under compression,

applying a thermoplastic coating material to the surface of the felt, surface heating the felt to a temperature above the melt point of the coating material, and chilling the felt surfaces to set the coating material.

8. In the method comprising forming a felt of mineral wool fibres with a binder disseminated throughout the felt, the improvement comprising heating the felt to soften the binder, and while said binder is in its softened state simultaneously surface heating the felt and compressing it to substantially its finished thickness, maintaining the felt at such thickness and cooling the same to set the binder.

9. In the method comprising forming a felt of mineral wool fibres with a thermoplastic binder disseminated throughout the felt, the improvement comprising employing the binder in aprolie portion of the order of 10 to 30% by weight of the fibres, heating the felt to soften the binder, and while said binder is in its softened state simultaneously surface heating the felt and compressing it to substantially its finished thickness, maintaining the felt at such thickness and cooling the same to set the binder.

10. In the method for the manufacture of felted mineral wool products comprising forming an air suspension of newly formed mineral wool fibres and a thermoplastic binder, the improvement comprising employing the binder in a proportion of the order of 10 to 30% by weight of the fibres, felting the fibres in a blow chamber with the binder substantially uniformly disseminated throughout the felt, heating the felt in the blow chamber to soften the. binder, and while said binder is in its softened state simultaneously surface heating the felt and compressing it to substantially its finished thickness, maintaining the felt at such thickness and cooling the same to set the binder.

11. In the method comprising forming a felt of mineral wool fibres with a thermoplastic binder present in a proportion of the order of 10 to 30% by weight of the fibres and disseminated throughout the felt, the improvement comprising warming the felt by the circulation of heated air therethrough with the air at a temperature of from 200-350 F. to plasticize the binder while maintaining the felt against substantial disarrangement of the fibres therein, and while said binder is in its plasticized state simultaneously surface heating the felt to a temperature of from 300- 500 F. and compressing the felt to substantially its finished thickness, and cooling the felt by the circulation of air therethrough while maintaining the felt under compression.

HAROLD T. COSS. LOUIS A. HAWTHORNE. JOSEPH H. ZET'I'EL.

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