US3381069A - Method for producing a fibrous mat - Google Patents

Description

April 30, 1968 A. SIMISON METHOD FOR PRODUCING A FIBROUS MAT 2 Sheets-Sheet 1 Filed July 15, 1965 W T3 M 5 4 m 4 ,47 TOP/v.06

April 1968 A. L. SIMISON 3,381,069

METHOD FOR PRODUCING A FIBROUS MAT Filed July 15, 1965 2 Sheets-Sheet 2 Li 2/1? M22 1) 13% E2 INVENTOR film/v A. 5/M/50/v United States Patent 3,381,069 METHOD FOR PRODUCING A FTBROUS MAT Alien L. Simison, Newark, Ohio, assignor to Owens-Corning Fiher ias Corporation, a corporation of Delaware Filed duly 15, 1965, Ser. No. 472,100 7 Claims. (Cl. 264-91) ABSTRACT OF THE DISCLOSURE A method for making a fibrous mat from Waste gatherings of fibers which are horizontally discharged from a toothed cylinder and joined with a merging air stream mixing with the fibers to carry them through a horizontal guiding spout. A binder suspension is sprayed from above and below on the emerging stream of air and fibers which pass to a foraminous receiving surface having suction means therein to draw the fibers and binder into a composite mat.

This invention relates to a method for producing a fibrous mat. Vfhile the invention is particularly concerned with the production of relatively thick bonded mats of fibrous glass, it is also applicable to forming thin felted structures and mats composed of other fibers both natural and synthetic, or a combination of various fibers.

An outstanding characteristic which this invention contributes to the products thereof is thorough and uniform integration, derived from the fine and eifective distribution of the binder particles through the body of fibers. This feature is of high value in many forms of blankets and boards for heat and sound insulation, cushioning, padding and fil ering. The range of specific uses for the products include roofing insulation; duct lining; insulating automobiles, trucks, trailers, and railroad cars; mattresses; and blanketing of concrete during curing.

The practice of the invention has been found highly useful in producing bonded mats from a blend of reprocessed fibrous glass including strands originally intended for textile processing and trimmings and rejected material from various fibrous glass mat forming operations.

In order to present the invention in a more concise and more easily understood manner this disclosure will be directed principally to the practice of the invention in connection with the employment of fibrous glass stock.

The main object of this invention is to provide a method for producing an improved bonded fibrous mat.

A further object is a method for refiberizing fibrous bodies and forming a mat therefrom, and economically and etliciently dispersing binder particles among the fibers of the mat.

More particularly an object of the invention is to produce an airborne stream of fibers from fibrous material and to introduce into the stream of fibers finely atomized airborne binder particles in a liquid carrier.

Another object of the invention is to form a wide, smooth surfaced, fibrous mat of uniform thickness and density.

A still further object is to efiectively and uniformly combine a mixture of different fibrous components in a fibrous mat after first fiberizing such components.

These and other objects of the invention have been attained in one mode of practicing the invention by mixing and fiberizing reject fibrous glass strands and trimmings and other waste or excess portions of fibrous glass mats, by creating a generally horizontally directed airborne stream of such regenerated fibers, dispersing binder particles through the stream by projecting such particles in a liquid carrier against the upper and lower sides of the ice stream, collecting the fibers and binder particles in intermingled relation on a foraminous conveyor in mat form, compressing the mat, and setting the binder to integrate the mat.

In the processing of such scrap material in practicing my invention the fibrous glass strands are removed from the cylindrical holders on which they are originally packaged for textile use by splitting the body of strands with a knife. The bulk strands are then fed through a chopper and cut to an average length of one and one half inches. If the water size ordinarily applied to textile strands has not dried, heat is then applied to the chopped strands. The chopped strands are subsequently delivered at a weight controlled rate to a raw material conveyor by a picker feeder.

A similar picker feeder adds a weight controlled proportion of the admix of waste fibrous glass mat material to the cut strands on the conveyor. The mat material may in one instance constitute thirty percent of the full batch.

The combined components are mixed and further shredded by being passed through a picker from which the batch is delivered through an air duct to the feeder of a garnett machine. The toothed cylinders and worker rolls of this machine separate, straighten and arrange the fibers uniformly in a loose progressing web. This web is disintegrated in being discharged through a guiding spout from the garnett machine in an air stream and the fibers are airborne as a spreading cloud.

As this stream of fibers is directed horizontally into the mat forming hood over a foraminous fiber receiving conveyor, series of atomizing nozzles above and below the stream project airborne liquid binder particles thereinto.

The fibers with the binder particles intermixed therewith fall within the chamber through gravitation and as influenced by a downward air draft drawn down through the foraminous conveyor, and settle on the conveyor which is traveling in line with the discharge path of the fibers.

The fibers with the binder particles precipitated thereon accumulate in a low density pack in a thickness depending upon various factors including the speed of the conveyor and which is generally established in a range between six and eight inches.

The pack is carried into a curing oven between conveyor flights which compress the pack to the thickness desired in the final mat product which is usually between one and three inches. With the pack so compressed the binder is cured to permanently establish the flexibility, thickness and density of the product.

On leaving the oven the mat is cut lenghtwise into desired widths and the edges trimmed. The action of a cross chopping knife determines the length of the iridividual mats which are then rolled up on a mandrel for storage, further processing or shipment.

The method of this invention while generally following the outlined procedure involve considerable variations therefrom and is mainly concerned with improved methods and apparatus associated with the entry and reception of the fibers and binder particles in the forming chamber. Accordingly, the following description and the accompanying drawings are directed largely to this stage in the formation of such bonded mats.

In FIGURE 1 of the drawings the outlet end of a garnett machine and the entering end of an associated forming hood are shown in side elevation;

FiGURE 2 is a plan view of the apparatus of FIG- URE 1;

FIGURE 3 is an enlarged side elevation largely in section of the fiber discharging portion of the garnett machine of FIGURES 1 and 2, as viewed from the opposite side thereof;

FIGURE 4 is a side elevation on a reduced scale of the outlet end of the garnett. machine and the main section of the forming hood; and

FIGURE 5 is a planview of the apparatus of FIG- URE 4.

Referring to the drawings in more detail, the outlet end of the garnett machine 11 is suported upon a base 10. A low speed doffer cylinder 12 removes the web of worked fibers from the first main cylinder (not illustrated) of the garnett machine. For producing a fibrous mat with an effective width of eight feet the garnettmachine here utilized forms a web six feet in width.

The small stripper roll 16 cooperates in the transfer of the web from the doifer cylinder 12 to the final high speed main cylinder 14, while a relatively slow worker roll 17 combs the fibers of the web before the web is propelled from the cylinder 14 into the path of the air air spouts 18. In this particular embodiment the cylinder '14 is thirty inches in diameter and is driven at an r.p.m.

of 1100. The web is accordingly carried by this cylinder at a linear speed of about 8600 feet per minute.

There are one hundred teeth per square inch of surface area of the cylinder 14. Each tooth would carry a single fiber under optimum conditions. A very satisfactory separation or spread of the fibers over the teeth is secured and the thin resulting web with air propelled by the teeth is discharged at high velocity into the slower air blast from spouts 18.

As may be better noted in FIGURE 3 there is an open area 23 above a top portion of the cylinder 14 into which the web of fibers is thrust. The web in disintegrated form then travels through the guiding spout 20. The top wall 21 of the spout may be positioned to establish the desired height of the air channel therethrough.

For the purpose of eliminating hang-up of fibers at the beginning edge of the lower wall of the guiding spout 20 a small two inch roller 24 is mounted adjacent thereto. This may be forcibly rotated as indicated by the arrow thereon at a speed for instance of 100 r.p.m. However, freely mounted it has been found to rotate under the action of the air stream thereover and to thus satisfactorily fulfill its function.

The guiding spout 20 is preferably composed of Lu-. cite, an acrylic plastic produced by the E. I. du Pont Company or of other electrical insulating material. Because of electrical charges apparently accumulated 0n the glass fibers during their travel through the garnett machine the fibers have been found to collect on metal walls of such a spout. The insulating character of Lucite overcomes this attraction and surfaces thereof remain clean of fibers. The guiding spout 20 in the present embodiment is dimensioned to provide an air passage therethrough approximately two inches high, six feet wide and two feet long. The air in an estimated volume of forty five hundred cubic feet per minute flows through spout 20 at a velocity of forty five hundred feet per minute.

From the comparatively restricted passage through the guiding spout 20 the air borne stream of fibers is directed into the expanding spout 27 which is also composed of Lucite for reduction of electrostatic attraction. A con siderable volume of additional air is drawn therein from the spacing between the spouts. Upper and lower louvers 29 and 30 at the outlet of the spout 27 are set to constrict and direct the air borne stream of fibers in a path found most effective in propelling the fibers into the forming hood 34. The passage through the expanding spout 27 is six inches high, six and one half feet wide, and four feet long. The larger cross sectional area of spout 27 permits the volume of air to be greatly expanded by induction with some decrease in the velocity of the air stream as projected from spout 20.

- As the cloud of fibers 32 travels into the forming hood 34 particles of binder 33 are directed thereinto from air atomizing nozzles 40 set in aligned series of sixteen 4 nozzles both above and below the path of the fibers and spaced from twelve to fifteen inches therefrom. Air is delivered to the nozzles through lines 41 while the binder solution reaches the nozzles through lines 42 from metering pumps 44. Valves 45 in the'binder lines provide shutoff means in case all of the nozzles are not required.

Through the number and close array of the atomizing nozzles which may be spaced little more than four inches apart the binder through each nozzle is reduced to an amount that may be thoroughly and finely atomized. With the metered control this provides very uniform and effective dispersion of the binder particles among the fibers. The small size of the particles in combination with the volume of air into which they are projected efiects rapid evaporation of the liquid vehicleor carrier of the basic binder material. So little moisture (in case the vehicle is water) is retained on the deposited particles that no heat for drying is required prior to the final setting of the binder. v

The fine atomization of the bindersolution results in the binder particles averaging only ten microns in diameter with very few reaching a diameter of one hundred microns.

A preferred binder composition is a ten percent phenol formaldehyde water solution with the resin in A state of polymerization. This may be introduced by the atomizing nozzles at a rate supplying a residual binder component of fifteen percent of the total weight of the final mat product. Under a comparatively high production schedule approximately six ounces of the water suspension of binder per minute is then atomized by each nozzle. However, more or less binder may be utilized according to the degree of stiifness and integrity desired in the final product. Many other binder materials of natural or synthetic origin may of course be utilized in place of the specific presently preferred resin.

The fine binder particles enter and spread through the flowing stream of air and fibers. The high volume of air including that'directly from spout 27 and that induced into immediate joinder therewith adjacent the outlet of spout 27 probably exceeds twenty thousand cubic feet of air per minute. Dispersed evenly through this mass of air, constituting approximately only one part by volume to three hundred thousand parts of air are the glass fibers, mostly as individual fibers in spaced relation, but also in small clumps rarely containing as many .as fifty fibers. The dispersion however, of the fibers and tiny binder droplets in the air is so thorough that each cubic inch of air will usually contain about twenty five or more fibers and roughly two hundred droplets of binder. Eventual contact and adhesive of binder particles to substantially all of the fibers is thus assured. No appreciable number of clumps of the fibers are of such a size to prevent an effective deposit of binder therethrough even though the power of moist-binder particles to penetrate into fiber clumps is very limited.

The fibers 32 with the intermingled particles of binder are drawn down upon the nine foot wide conveyor 36 by gravity and the downward flow of air through the conveyor into the suction chamber 38. Groups'of lateral air ducts 39, 49, 51 and 53 provide paths for air drawn from the chamber 38 by suitable air blowers into the common air plenum 54. Through adjustment of dampers 37 "in the air ducts the air suction may be varied along the chamber 38.

Air flow into the forming hood 34 is derived fromt'he air from spouts 18 greatly augmented by air projected from'the peripheral surface of cylinder 14, extra air induced into the second guiding spout 27, to a minor extent from the atomizing air from nozzles 40, andmajorly from air entering the open'face of the forming hood. Additional air moves into the forming'hood through openings 58 in the ceiling panel 59 of the forming hood and through openings 55 above side panels 56 of the hood.

Further sections of the forming hood are closed by top panels 60 and side panels 62.

The velocity of the air borne stream of fibers 32 from the outlet of spout 27, estimated to approach 4000 feet per minute in a possible volume of 15000 cubic feet, induces a fiow of a large volume of surrounding air into the open face of the forming hood which is spaced above two feet from the spout outlet. This added air while slowing and somewhat expanding the fiber movement helps bring the fibers and binder particles down upon the conveyor as such added air moves downwardly in response to the air suction. This suction of air into the chamber 38 below the conveyor is at such negative pressure and in suficient volume to rapidly draw the main mass of fibers down upon the first portion of the conveyor surface.

The closed sides of the hood along the borders of the fiber stream as well as the suction at the edges of the conveyor spreads the deposit of fibers and binder particles across the conveyor. The air passes down through the screen conveyor which in effect thus filters the fibers from the air. The fibers in turn serve as a filtering body for the binder particles intermingled therewith.

Eddies of air in the upper region of the hood are curtailed by air movement through top openings 57 and 58 and side openings 55. In this embodiment the thirty foot long forming hood 34 extends four feet above the surface of the conveyor 36 and is approximately as wide as the nine foot width of the conveyor. The openings 57 and 58 in the fore part of the top of the forming hood are five feet long and three feet wide while the openings 55 above the side panels 56 are ten feet long and one foot Wide. The top and sides of the hood are otherwise closed up to the discharge end of the hood.

From the forming hood 34 the mat of fibers and binder particles is transported through a curing oven of conventional design. The mat is there compressed to the desired thickness (unlikely to exceed three inches) and density (as high as ten pounds per cubic foot but usually below three pounds) between opposed flights of upper and lower conveyors while air heated to 350 F. is driven through the foraminous conveyor flights and the compressed mat to cure the binder particles and thus integrate and set the mat in the selected thickness and density.

After being thus cured the mat moves through edge trimmers, longitudinal slitters, and cross cutting devices to form units of desired widths and lengths. In the present example a mat eight feet wide remains after the edge trimming operation and is slit in half to form four foot rolls wound on stocking mandrels. The edge trimmings are salvaged and added to the raw material to be subsequently processed.

Because of the fine atomization of the binder and thorough and uniform dispersion of the particles through the fibrous stock, the final products have unusual integrity and homogeneous characteristics. While different proportions of the binder may be utilized depending upon the degree of strength and rigidity required, because of its original liquid nature and its even distribution a minimum amount is effective and is highly economical. This superior performance is especially valuable where a mixture of fibers of dilferent lengths and sizes is involved as in the processing with which this invention is particularly concerned.

The principal features which contribute to the success of this invention include the spout means for directing and expanding the high velocity air borne stream of fibers, the discharge of the fibers through an open area before they enter the forming hood, the projection of atomized liquid binder upon opposite sides of the planar stream of fibers in the open area, the metered supply of the binder to a high number of closely arranged nozzles, and the controlled air flow into the open face of the hood and through openings in the sides and top thereof down through the foraminous conveyor.

Having thus described my invention in detail with respect to one mode of practice thereof, it will be understood that obvious substitutions and variations in the materials and structures set forth may be made without departing from the spirit of the invention and the scope of the following claims.

I claim:

1. A method for producing a bonded fibrous mat which comprises separating and combing gatherings of fibers in a garnett-type machine, discharging the fibers horizontally and tangentially from the upper surface of a toothed cylinder of the machine, directing a stream of substantially unheated air over the upper surface of the cylinder into traveling association with the fibers, directing the combined stream of air and fibers through a fiat horizontal guiding spout, projecting binder particles in a liquid carrier into the upper and lower sides of the horizontal stream of air and fibers issuing from the spout, and drawing the fibers and binder particles by suction downwardly for deposit upon a receiving surface.

2. A method according to claim 1 in wr ich the binder particles are projected from upper and lower series of closely arrayed nozzles spaced on the average no more than five inches apart.

3. A method according to claim 1 in which a major proportion of the liquid carrier for the binder particles is evaporated before the binder particles reach the receiving surface by being finely atomized by the projection means as particles averaging no more than one hundred microns in size and by being exposed to a large flow of ambient air.

4. A method according to claim 1 in which an open faced hood is positioned in generally enclosing relation over the receiving surface, and the stream of air and fibers is directed through an open area before entering the hood and being deposited upon the receiving surface, whereby additional air is induced by the stream to flow along with it into the hood, and the binder particles are directed into the stream of air and fibers immediately before the stream enters the hood.

5. A method for producing a fibrous mat from gatherings of fibers which comprises combing and separating the fibers of such gatherings, propelling the fibers in a high velocity stream horizontally and tangentially from the upper surface of a toothed cylinder, directing a blast of substantially unheated air at a velocity lower than the velocity of said fiber stream over the upper surface of the cylinder into merging relation with the stream of fibers, directing fine particles of a liquid binder into the combined stream of air and fibers and drawing the combined stream of air, fibers and binder particles down upon a foraminous receiving surface.

6. A method according to claim 5 in which ti e combined stream of air and fibers is confined prior to the directing thereinto of the binder particles and while confined said combined stream is augmented with additional air.

7. A method according to claim 6 in which the final proportion by volume of the fibers to the air component of the combined stream is roughly one to three hundred thousand and the binder component amounts roughly to only one quarter of the fiber component.

References Cited UNITED STATES PATENTS 3,081,207 3/1963 Fox 264121 FOREIGN PATENTS 517,591 10/1955 Canada. 633,360 12/1961 Canada. 634,668 1/1962 Canada.

ROBERT F. WHITE, Primary Examiner.

I. R. HALL, Assistant Examiner.

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