US3861971A

US3861971A - Method of producing a board of fibrous glass and the product thereof

Info

Publication number: US3861971A
Application number: US078532A
Authority: US
Inventors: Stuart H Stapleford; Charles E Nutter
Original assignee: Owens Corning Fiberglas Corp
Current assignee: Owens Corning
Priority date: 1969-11-06
Filing date: 1970-10-06
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21

Abstract

A thermal insulating roofing board of bonded, randomly and spacedly positioned individual, discontinuous glass fibers, with an asphaltic saturated surface layer including bundles or strands of glass fibers distributed over the upper surface of the board under a top surfacing sheet, said board being produced by forming and discharging individual, discontinuous fibers downwardly with particles of binder intermingled therewith to form a pack upon a conveyor receiving surface, compressing the pack under a roller, depositing bundles or strands of glass fibers upon the upper surface of the pack, compacting the pack in board form and curing the binder particles to dimensionally stabilize the pack in such form, applying heated asphalt to the upper surface of the stabilized compacted pack to impregnate the upper stratum thereof, including the bundles or strands of glass fibers and applying a top surfacing sheet over the applied asphalt.

Description

United States .Patent [191 Stapleford et al.

[ METHOD OF PRODUCING A BOARD OF FIBROUS GLASS AND THE PRODUCT THEREOF [75] Inventors: Stuart H. Stapleford, Atlanta, (3a.;

Charles E. Nutter, l-lebron, Ohio [73] Assignee: Owens-Corning Fiberglas Corporation, Toledo, Ohio [22] Filed: Oct. 6, 1970 [21] Appl. No.: 78,532

Related U.S. Application Data [63] Continuation-in-part of Ser. No. 874,428, Nov. 6,

1969, abandoned.

[ Jan. 21, 1975 FORElGN PATENTS OR APPLICATIONS 702,075 l/l965 Canada 161/155 Primary Examiner-George F. Lesmes Assistant Examiner-Paul J. Thibodeau Attorney, Agent, or FirmCarl G. Staelin; John W. Overman; William P. Carr [57] ABSTRACT A thermal insulating roofing board of bonded, randomly and spacedly positioned individual, discontinuous glass fibers, with an asphaltic saturated surface layer including bundles or strands of glass fibers distributed over the upper surface of the board under a top surfacing sheet, said board being produced by forming and discharging individual, discontinuous fibers downwardly with particles of binder intermingled therewith to form a pack upon a conveyor receiving surface, compressing the pack under a roller, depositing bundles or strands of glass fibers upon the upper surface of the pack, compacting the pack in board form and curing the binder particles to dimensionally stabilize the pack in such form, applying heated asphalt to the upper surface of the stabilized compacted pack to impregnate the upper stratum thereof, including the bundles or strands of glass fibers and applying a top surfacing sheet over the applied asphalt.

1 Claim, 6 Drawing Figures PATENTED JAN? I975 SHEET 2 [IF 2 k seas Wmw INVENTORS 5704/27 5MP: [Fem & BY 0/: 5 M075 M? W ATTORNEYS METHOD OF PRODUCING-A BOARD OF FIBROUS GLASS AND THE PRODUCT THEREOF This application is a continuation-in-part of application Ser. No. 874,428 filed Nov. 6, 1969, now abancloned.

BACKGROUND OF THE INVENTION This invention relates to a board composed principally of bonded fibrous glass and to such a board primarily intended for roof insulation.

The roofing boards of this invention are designed mainly for flat or low-pitched roof decks that may be surfaced with a built-up bitumen-bonded roofing. The boards are laid directly over the roof deck whether wood, steel, concrete or precast slabs.

BRIEF SUMMARY OF THE INVENTION A principal object of this invention is a method of producing ,a roofing board by which the board may'be economically and completely fabricated in a continuous production line utilizing a reduced number of components and fewer steps in the manufacturing process.

A concomitant purpose is to provide an insulating board that amplifies the overall strength of a built-up roof structure.

A further object of the invention is a method of producing a generally air permeated, thermal insulating fibrous board that has a surface stratum of extra density and strength with exceptional resistance to compressive and puncturing forces.

Another object of the invention is the processing of a roofing board with sufficient rigidity and attachment characteristics to withstand uplifting under high winds from its installed position in a roof structure A still further object of this invention is a method of applying a surface layer of strands of fibrous glass upon the board. These and other objects and advantages of the invention are attained principally through a method of constructing a fibrous board with randomly positioned, individual, non-continuous glass fibers extending in spaced and resinously bonded relation throughout the main area of the board, having bundles or strands of glass fibers upon the upper surface of the board, having the individual glass fibers and the bundles or strands of glass fibers bonded together by an asphaltic impregnation, and finally, covering the upper surface of the board with a top surfacing sheet.

BRIEF DESCRIPTION OF THE DRAWINGS The successful practice of the invention is further promoted by supplemental features set forth in the subsequent description and accompanying drawings in which:

FIG. I is a longitudinal, partly sectional, elevational view of a fiber forming and collecting apparatus including a series of rotary type fiber forming units, a fiber collecting conveyor, and compressing conveyor flights passing through a binder curing oven;

FIG. 2 is a longitudinal vertical sectional view of a modified form of apparatus including the lower portion of the last fiber forming unit with a chopped strand applicator after the crushing roll of FIG. 1;

FIG. 3 is a diagrammatic side elevational view of apparatus comprising a continuation of the production line starting with the apparatus of FIGS. 1 and 2 and including'a conveyor, an asphalt applicator and other processing devices;

FIG. 4 is a cross section of the apparatus of FIG. 3 taken on the line 4 4 thereon;

FIG. 5 is a side elevation of a longitudinal portion of the conveyor of FIG. 3 with associated devices adapted for practicing an alternate method of the invention; and

FIG. 6 is perspective view of a broken corner portion ofa roofing board produced by the modified method of the invention involving the apparatus of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring in more detail to the drawings, suitable equipment and processing procedure for fabricating the boards are presented in FIGS. 1, 2, 3, 4, and 5. At the start of the production line of FIG. I there is shown a portion of a glass furnace 10 with a forehearth 11 extending therefrom. A series of ported bushings 12 are mounted upon the lower side of the forehearth II. Streams 14 of molten glass issue downwardly from the bushings into a series of seven rotary fiber forming units of which only three, 16 and 18, the first two, and 20, the last of the series, are here illustrated.

The rotary forming units are all alike and of a conventional design including an upper housing 22 supported upon a carriage 24 movable mounted upon tracks 26. This arrangement permits each unit to be temporarily transferred from the hot area of the forehearth for inspection and maintenance requirements.

As may be seen in the sectioned portion of rotary unit 20, the stream 14 of molten glass is directed downwardly through a hollow tube or quill 28 extending from the upper end of housing 22 down to a centrifuge 30 to which it is joined. The quill and centrifuge are rotatably driven by a motor within housing 22. The molten glass is fiberized by being centrifugally forced through orifices in the peripheral surface of centrifuge 30. From chamber 32 hot combustion gases are discharged down upon the upper surface of the centrifuge 30 to maintain it at molten glass temperature.

The primary fibers issuing laterally from the orificed peripheral surface of the centrifuge 30 are blown downwardly within the cylindrical shield 34 and are further attenuated therein by a blast of combustion gases from the annular burner 36. The resulting whirling veil of fibers 38, with the combined streams of hot gases from chamber 32 and burner 36, descends through guiding spout 40. The fibers may be between twenty-five and sixty hundred thousandths of an inch in diameter but preferably have a diameter of approximately thirty-nine hundred thousandths.

A series of nozzles 42 around the lower edge of spout 40 project resinous binder particles 44 into the veil of fibers 38 prior to the entry of the fibers into the forming hood 46. In this instance a vertical partition 48 within the hood secludes the fibers from the last rotary unit 20 and fibers produced by the preceding rotary units in their descent to the foraminous conveyor 50, traveling over suction chamber 52. Similary a partition 48a sequesters the fibers delivered from the first unit 16.

Phenol formaldehyde is the preferred binding agent, but it has been well established that various other resinous materials such as epoxies, urea and malamine form aldehydes also give excellent results. The amount of the binder utilized is advisbly in the region of nine per cent by weight of the full fibrous pack but may be varied within a range roughly of five to fifteen per cent withthe cost factor tending to discourage higher quantities, and diminishing strength accompanying the use of lower amounts.

Chopped strands 57 are mixed with the fibers produced by rotary unit by the combination chopper and blower 56. This draws strands 54 from an aligned series of strand packages such as the single spool or bobbin 55 illustrated and projects the chopped strands into the upper end of the portion of the hood 46 which is confined by partition 48.

The chopped strands 57 are desirably cut to lengths between two and four inches and in the example of processing herein selected for purposes of explanation amount in weight to at least ten per cent of the weight of the non-continuous fibers from rotary forming unit 20 with which they are combined. With a conveyor speed of sixty feet per minute and a deposited fibrous pack four feet wide intended for forming a roofing board one inch in thickness, the chopped strands would be introduced at the rate of roughly two and one half pounds per minute.

The basic strands 54 may be of a size providing about 15,000 yards per pound and be composed of two hundred continuous filaments of an approximate diameter of thirty seven, hundred thousandths of an inch. Alternately, the individual strands may contain some four hundred continuous filaments with a diameter around twenty five, hundred thousandths of an inch.

Feeding of the chopped strands may be considerably advanced by bundling them into loose rovings upon the packages 55 and passing the rovings through the chopper 56. Sixty strand ends may, for example, be so gathered together in each roving and six or more of such rovings be fed in spaced relation through the chopper 56, the latter being of appropriate length, such as four feet in this instance, to discharge the chopped strands across the width of the hood 46. Through the whirling and turbulent downward movement of the veil of the fibers 38 and binder particles 44 in the accompanying combustion gases, the chopped strands 57 are thoroughly intermixed with the fibers.

Other forms of strands of filaments in side by side, parallel relation including fibrous glass yarns and cords in short or continuous lengths may be utilized in differing quantities for effective practice of the invention.

The pack 58 accumulated within hood 46 includes the fibers produced by the full series of seven rotary fiber forming units. As the fibers from rotary unit 20 are the last to be deposited upon the pack 58 there is formed a distinct upper stratum 62 constituting a defi nite proportion, in this instance one seventh, of the total thickness of the pack 58, throughout which the chopped strands are exclusively distributed.

If it is desired to have a strengthening stratum on the bottom of the pack 58, in addition to the upper stratum 62, strands are fed to the chopper 56a to project chopped strands into intermingling relation with the fibers downwardly discharged from the first fiberizing rotary unit 16. The fibers from this unit and the chopped strands added thereto are segregated during their descent and deposit upon the conveyor 50 by the partition 48a.

The pack 58 is carried by conveyor 50 under roller 64, which is preferably heated to decrease the propensity of the fibers to become attached thereto, and the pack is preliminarily reduced thereby to a compressed state 66 for introduction between upper and lower compression conveyor flights and 72 within oven 68. The thickness of the pack is permanently established by the setting of the binder within the oven. A continuous rigid panel 74 with a strand reinforced upper stratum 62, and in the thickness of one inch in this instance, is accordingly discharged from the oven.

Should a surfacing layer of bundles or strands of fibrous glass unmixed with the single fibers of the pack be desired they may be deposited after the formation of the pack and preferably after the pack has passed beneath the compression roll 64 as shown in the apparatus of FIG. 2.

In this arrangement, chopped strands 57 are discharged from the combination chopper and blower 56b down within chamber 57 upon the surface of the pack 58 in its compressed state 66 after it has passed beneath the roller 64'and before the pack is introduced between the flights 70 and 72 within oven 68. This deposit 62a of chopped strands lies rather loosely but is held in position by the portion of the binder upon the surface fibers of the pack and remains in distributed position upon the pack through the oven 68. The subsequent surface impregnation of asphalt amounting to three thirty seconds of an inch for stratum 62a of loose strands integrates the chopped strands and the cured pack.

Alternately the chopped strands may be placed upon the pack after it has passed through the oven just prior to the application of asphalt. One pound of chopped strands per one hundred square feet of surface serves very adequately.

The density of the panel 74 in its final compressed state should not be below seven and one-half pounds per cubic foot in order to maintain high compressive strength in the fibrous boards, and preferably should not exceed nine pounds for retention of the porosity required for superior thermal insulation.

In travel through the oven there is migration of binder to the bottom of the pack which, with the pressure exerted by the compression of the conveyor flights and some concurrent reorientation of the fibers, effects an extra smooth and tougher surface on the bottom of the panel 74. This assures easier and better conforming installation of the roof boards on smooth roof surfaces as particularly presented by metal roofs.

From the oven 68 of FIG. 1 the panel 74 with its upper stratum 62 reinforced with chopped strands 57 moves along the conveyor line 76 diagrammatically shown in FIG. 3. As a final step of the processing procedure followed along conveyor line 76, a vertically reciprocating chopping knife 78 severs the panel 74 crosswise into individual board units 79. The panel 74 is usually four feet in width, standard fixed dimension of the roofing boards. According to the timing of operation of the knife 78 the other planar dimension of the boards may be within a broad range but most commonly is wither two, three or four feet.

Residual heat from the binder curing temperature utilized in the oven is retained in the panel 74 as it passes beneath the asphalt coater 80 to which asphalt in a controlled volume is delivered by pump 86. The desired fluidity of the asphalt passing through the coater is maintained by an associated heater 88.

A thin continuous curtain 81 of asphalt flows downwardly from the coater acorss the upper surface and slightly over the edges of the boards 79 whereby the side edge surfaces are also coated as may be best in FIG. 4.

Due to the porosity of the panel 74 the asphalt sinks into the upper stratum 62 or 62a thereof and slightly into the surfaces of the opposite side edge portions. The penetration of the asphalt is predetermined by the amount thereof, its controlled fluidity and supplementally by the hardening of the asphalt from the chilling effect of the high water content of the parting agent 94 subsequently discharged upon the boards by a crosswise series of nozzles 92. v

Through this controlled entry, the asphalt impregnation is restricted to the full or major portion of the thickness of upper stratum 62 amounting in this example to one seventh of the full thickness of the panel 74. The high porosity and attendant thermal insulating capacity of the main portion of the panel is thus preserved.

The preferred asphalt for impregnation of the upper stratum is a steep asphalt having a softening point between 180 F. and 190 F; One having a softening point below 170 F. is not recommended while asphalts with melting points as high as 250 F. would ordinarily give very satisfactory service. In the applicator 80 the asphalt is maintained at the desired fluidity by being heated to between 340F. and 425 F. and normally between 350 F. and 375 F.

From approximately four to seven and one-half ounces of the asphalt is applied to each square foot of surface of the panel 74. The maximum is sufficient to thoroughly saturate the upper stratum 62, with some asphalt likely retained upon the surface of the units.

While a steep asphalt is preforably utilized other bituminous materials may serve adequately the term asphalt when appearing herein should be intepreted as possibly containing asphaltenes, tarry substances, petroleum residues, pitches, road oils, albino asphalt, cutbacks, solutions or dispersions and cracked, straight run or natural asphalts.

The final hardening of the asphalt and cooling of the panel is further promoted by the spraying of water from nozzle means 96 and high velocity air jets from nozzles 98, the latter mainly utilized to drive and evaporate water from the surface of the panel.

The parting agent 94 forms a porous coating primarily for the purpose of preventing sticking of adjacent boards due to the asphalt impregnant when the boards are stacked in shipping packages. The parting agent is a heavily pigmented latex composition with a polyvinyl acetate or other resinous base.

A comparatively low temperature of the parting agent dispersion and the evaporative action of the water content has a considerable cooling effect on the asphalt impregnant and is a factor in determining the depth of penetration.

Conversely, the residual heat of the panel 74 and of the asphalt promotes the practically instantaneous setting of the parting agent.

Apparatus for following another form of the method of this invention is depicted in FIG. 5. As there shown a, polyethylene film 101 is directed down upon the panel 74 by rolls 103 and 105 as a parting agent in place of the material 94 applied by nozzles 92. A film one-half a mil in thickness serves very satisfactorily.

Roll 105 chilled by water sprayed thereon by nozzles 106 and by water introduced within it cools the film 101 and therethrough reduces the temperature of the seen asphalt impregnation of the panel 74 to about F. which is well below the melting point of the film composition. Additional water and air cooling treatment such as provided by nozzles 96 and 98 is not required. The film may be softened to a slightly tacky condition by the residual heat of the asphalt and is thereby better attached to the panel. Guides 107 and rollers 108 turn the edges of the polyethylene film 101 downwardly and presses them in adhering relation against the side edges of the panel 74.

The film and roll [05 have a smoothing effect upon any concentration of asphalt left upon the surface of the panel 74. Besides serving as a more uniform parting agent than the material 94 when the resulting boards 79 are stacked for shipping or storage, the film also opposes injury of the board during handling and installation of the boards.

Because of its lower melting point of around 220F. the low density polyethylene film is liquefied and is disintegrated in any hot asphalt that may be later mopped over the boards, the temperature of which usually ranges between 375F. and 425F. A direct bond is thus secured between the mopped asphalt and the asphalt surface coating of the board.

A polyethylene film from 0.0002 to 0.001 or one mil in thickness is disintegrated under the heat of mopped asphalt. Films within this same thickness range of other compositions such as polypropylene also dissintegrate sufficiently to permit union between the asphalt topping of the board and heated asphalt applied in building a built-up roofing structure. Surfacing films or sheets of other materials are also adaptable for delivery over a chilled roll for cooling the asphalt impregnation and smoothing its surface.

The covering films or sheets for use in this invention are preferably resinous, imperforate and nonabsorbing. The conventional kraft paper covering of roofing boards may carry moisture when originally wrapped upon the board core or wick moisture from the edges of the boards after installation in a built-up roofing. In either case the moisture involved expands under solar heat and is apt to form disruptive bubbles in the roofing surface. Also, such paper coverings con tract when drying out and may warp the boards into saucer shapes. With any imperforate covering air may be trapped within the board and occasionally causes bubbles. Accordingly, a film that is dissolved or is disintegrated avoids this hazard.

A corner of the board with a polyethylene covering film produced according to this invention is depicted in FIG. 6.

Non-continuous glass fibers 38 extend throughout the board in individually spaced relation. Chopped strands 57 of fibrous glass are dispersed across the upper stratum 62. The strengthened and extra smooth bottom is indicated at 109.

Particles or small bodies 44 of binder are distributed throughout the board and secure the fibers 38 together at their crossover points and supplements the asphalt in integrating the chopped strands 57 with the main body of fibers.

The slightly higher concentration of the binder particles in the lower portion of the board, provides this section of the board with added rigidity and strength in relation to the midportion of the board. The limiting of asphalt to the upper stratum and the side surface portion leaves the balance of the board with high porosity and accompanying excellent heat insulating capacity.

Particular steps of the method deserving emphasis include depositing the glass strands upon an assembled and preliminarily compressed pack of individual fibers either before the binder thereof is cured and the pack is compressed to its final form, or just prior to the coating of the cured board with heated asphalt; covering the board with a cooled protective film while the asphaltic surface is still hot and thus reducing the temperature of the hot impregnant; smoothing the surface thereof with the application of the film under a chilled roll; and producing a board with an extra smooth and strong bottom for fitting against a smooth roof deck.

As those skilled in the arts involved may easily perceive various alterations and modifications may be made in the method of this invention without departing from the spirit thereof and the scope of the following claims.

We claim:

1. A method of producing a thermal insulating roofing board of bonded, randomly positioned and spacedly related individual, discontinuous glass fibers with strands of multiple glass filaments distributed over the top surface of the board in bonded relation with the individual glass fibers, said method comprising depositing upon a conveyor randomly positioned and spacedly related individual, discontinuous glass fibers as a pack with a heat settable resinous binder dispersed therethrough, passing the pack beneath a roller to initially compress the pack, distributing over the top surface of the pack short unshredded strands of definite and predetermined lengths and containing numerous closely grouped parallel filiments, dimensionally stabilizing the pack and providing rigidity for the resulting roofing board by heat setting the binder while compressing the pack to its final highly air permeated density, the setting of the binder cohering the adjacent glass fibers and the surface strands, as well as the glass fibers throughout the pack, placing a coating of melted asphalt upon the upper surface of the dimensionally stabilized pack to further cohere the fibers and the strands through the gravity motivated downward entry of the asphalt, limiting, through cooling means, the penetration into the pack of the melted asphalt to the glass fibers adjacent the top surface of the pack thus preserving the air permeated, thermal insulating properties of the major portion of the pack, and laying a surfacing sheet over the asphalt coated pack for attachment by the asphalt and for further cooling and hardening of the asphalt.