US3850601A

US3850601A - Method of producing a board of fibrous glass

Info

Publication number: US3850601A
Application number: US00371013A
Authority: US
Inventors: S Stapleford; C Nutter
Original assignee: Owens Corning Fiberglas Corp
Current assignee: Owens Corning
Priority date: 1969-11-06
Filing date: 1973-06-18
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

Producing an asphaltic surfaced thermal insulating roofing board of bonded, randomly positioned and spacedly related individual, discontinuous glass fibers with short bundles or strands of glass fibers distributed in intermixed and bonded relation with the individual glass fibers throughout a comparatively narrow surface stratum of the board by forming and discharging individual, discontinuous fibers downwardly with particles of binder intermingled therewith upon a conveyor receiving surface, depositing bundles or strands of glass fibers with or upon the upper surface layer of the individual glass fibers of the deposited 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 and side edges of the compacted pack to impregnate the upper stratum thereof, applying a parting agent over the applied asphalt, and cooling the upper surface of the pack with water to set the asphalt.

Description

United States Patent [191 Stapleiord et a1.

[451 Nov. 26, 1974 METHOD OF PRODUCING A BOARD OF FIBROUS GLASS [75] Inventors: Stuart 11. Stapleford, Atlanta, Ga.;

Charles E. Nutter, l-lebron, Ohio [73] Assignee: Owens-Corning Fiberglas Corporation, Toledo, Ohio [22] Filed: June 18, 1973 [2]] Appl. No.: 371,013

Related U.S. Application Data [63] Continuationof Ser. No.'874,428, Nov. 6, 1969,

@, time Primary ExaminerRobert L. Lindsay, Jr. Attorney, Agent, or FirmCarl G. Staelin; John W. Overman; William P. Carr [5 7] ABSTRACT Producing an asphaltic surfaced thermal insulating roofing board of bonded, randomly positioned and spacedly related individual, discontinuous glass fibers with short bundles or strands of glass fibers distributed in intermixed and bonded relation with the individual glass fibers throughout a comparatively narrow surface stratum of the board by forming and discharging individual, discontinuous fibers downwardly with particles of binder intermingled therewith upon a conveyor receiving surface, depositing bundles or strands of glass fibers with or upon the upper surface layer of the individual glass fibers of the deposited 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 and side edges of the compacted pack to impregnate the upper stratum thereof, applying a parting agent over the applied asphalt, and cooling the upper surface of the pack with water to set the asphalt.

1 Claim, 8 Drawing Figures METHOD OF PRODUCING A BOARD OF FIBROUS GLASS This is a continuation of application Ser. No. 874,428, filed Nov. 6, 1969, and now abandoned.

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 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 combining strands of fibrous glass with individual glass fibers in a stratum of a fibrous 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 in resinously bonded relation throughout the full area of the board including a definite planar stratum thereof, having bundles or strands of glass fibers in the planar stratum resinously bonded to the non-continuous fibers, and having the stratum saturated and further bonded by an asphaltic or other resinous impregnation.

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 ofa 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 the invention including the lower portion of the last rotary type fiber forming unit of the series shown in 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. I and 2 and ineluding 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 44 thereon;

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

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

FIGS. 7 and 8 are similar views of two other fibrous boards produced by the methods of the invention.

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. 1 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 11. 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 movably 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 molen glass is fiberized by being centrifugally forced through orifices in the peripheral surface of centrifuge 30. From chamber 34 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 stream 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 the 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 formaldehydes 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 of 5 to per cent with the 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 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 thehood 46 which is confined by partition 48.

The chopped strands 57 are desirably cut to lengths between 2 and 4 inches and in the example of processing herein selected for purposes of explanation amount in weight to at least 10 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 60 feet per minute and a deposited fibrous pack 4 feet wide intended for forming a roofing board one inch in thickness, the chopped strands would be introduced at the rate of roughly 2 and /2 pounds per minute.

The basic strands 54 may be ofa size providing about 15.000yards per pound and be composed of 200 continuous filaments of an approximate diameter of thirty seven, hundred thousandths of an inch. Alternately, the individual strands may contain some 400 continuous filaments with a diameter around twenty five, hundred thousandths of an inch.

Feeding of the chopped strandsmay be considerably advanced by bundling them into loose rovings upon the packages 55 and passing the rovings through the chopper 56. 6O 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 thefibers.

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 adefinite 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.

In case a more concentrated and thinner upper stratum including chopped strands 57 is preferred, the latter may be added with the modified structure illustrated in FIG. 2. In this arrangement a separate downward channel adjacent theoutlet of the hood 46 is provided by supplemental wall 59. Chopped strands are directed into this channel by chopper and air gun 56b.

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 70 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 1 inch in this instance, is accordingly discharged from the oven.

The density of the panel 74 in its final compressed state should not be below 7 and /2 pounds per cubic foot in order to maintain high compressive strength in the fibrous boards, and preferably should not exceed 9 pounds for retention of the porosity required for superior thermal insulation.

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 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 2, 3 or 4 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 across the upper surface and slightly over the edges of the boards 79 whereby the side edge surfaces are also coated as may be best seen in FIG. 4. 7

Due to the porosity of the panel 74 the asphalt-sinks into the upper stratum 62 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.

Through this controlled entry, the asphalt impregnation is restricted to the full or major portion ofthe 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 and F. One having a softening point below 170F is not recommended while asphalts with melting points as high as 250F would ordinarily give very satisfactory service. In the applicator 80 the asphalt is maintained at the desired fluidity by being heated to between 340 and 410F and normally between 350 and 375F.

From approximately 4 to 7 and /2 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 in any case retained upon the surface of the units. The rather rough surface of the basic fibrous glass panel derived from conveyor flight impression and the fibrous stock cooperates with the surface asphalt for attaching engagement with roofing materials which may later by superimposed upon the boards.

While a steep asphalt is preferably utilized other bituminous materials may serve adequately and the term asphalt when appearing herein should be interpreted as possibly containing asphaltenes, tarry substances, petroleum residues, pitches, road oils, albino asphalt, cut-backs, 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. It may be formulated according to Example 3 ofU.S. Pat. No. 3,239.475 modified by an increase of at least 50 and preferably about 100 per cent additional water and a reduction of lOper cent in the pigment content. The latex parting agent is applied in sufficient quantity to the surface of the panel 74 to leave after evaporation of the water vehicle about 3 and V2 grams of solids per square foot.

A comparatively low temperature of the parting agent dispersion and the evaporation 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 an alternate 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 satisfactory.

Roll 105 is chilled by water sprayed thereon by nozzles 106. This cools the film 101 and therethrough reduces the temperature of the asphalt impregnation of the panel 74. Additional water and air cooling treatment such as provided by nozzles 96 and '98 is not required. The film is softened to a tacky condition by the residual heat of the asphalt and is thereby being 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 105 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 facilitates handling and installation of theboards.

Because of its lower melting point the polyethylene film is liquefied and fuses with any hot asphalt that may be later mopped over the boards.

A corner ofa board produced by this invention is depicted in each of FIGS. 6, 7, and 8. It is the same basic board in all views with an upper stratum 62, but respectively shown are the board with a protective covering of polyethylene and a lower stratum 109 as well as an upper stratum 62 (FIG. 6), prior to an impregnation of asphalt (FIG. 7), and after such impregnation (FIG. 8).

Non-continuous glass fibers 38 extend throughout the boards in individually spaced relation. Chopped strands S7 of fibrous glass are dispersed throughout the upper stratum 62 (and lower stratum 109) which is comparably narrow in thickness with the chopped strands 57 uniformly intermingled with the fibers 38.

Particles or small bodies 44 of binder are distributed throughout the board and secure the fibers 38 together at their crossover points and to the chopped strands 57.

There is a slightly higher concentration of the binder particles in the lower portion of the board. This provides this section of the board with added rigidity and strength in relation to the midportion of the board, but still far below the upper stratum in these properties due to the presence there of the reinforcement of the chopped strands.

The upper stratum 62 is solidified and further strengthened by the impregnation thereof by steep asphalt 110 as shown in FlG. 8. An impregnating coating of asphalt is also shown on one edge surface of the board with only slight penetration. The limiting of asphalt to the upper stratum (and possibly also to the lower stratum should it be desired to invert the boards and apply asphalt to a strand reinforced lower stratum) and the side surface portion leaves the balance of the board with high porosity and accompanying excellent heat insulating capacity.

.This invention presents a method of producing a thermal insulating board primarily adapted for use in roofing. The method provides a densified stratum preferably adjoining the upper surface but positionable alternately or additionally intermediately or in the lower portion of the board. The stratum includes integrated fibrous glass elements such as chopped or continuous strands and may include in the upper and lower stratum a resinous impregnation, preferably of asphalt.

Particular steps of the method deserving emphasis include adding the glass strands to a whirling body of individual fibers, said body being a definite temporarily segregated portion of primary fibers being accumulated in a fibrous pack, alternately adding strands to an assembled pack of individual fibers before the binder thereof is cured and before the pack is compressed to its final form, introducing an impregnating and sealing resinous material into stratums of fibrous boards, covering the surface of the compressed pack with a parting agent while the surface is still heated from the application of a hotimpregnant, utilizing a thermoplastic reslnous film for said parting agent, and reducing the temperature of the hot impregnant with the application of the parting agent.

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 short bundles or strands of multiple glass filaments distributed in intermixed and bonded relation with the individual glass fibers throughout a narrow stratum of the board, said method comprising drawing individual fibers from molten glass and directing them downwardly in spaced and randomly positioned relation toward a transversely traveling receiving surface, dividing the descending fibers into separate groups, said groups positioned successively in the direction of travel of the receiving surface, combining a dispersed settable binder with the fibers of each group, combining and intermingling short bundles or strands of definite predetermined lengths and containing hundreds of glass filaments with the individual fibers and dispersed binder of the group of fibers leading the succession of groups in the direction of travel of the receiving surface, while leaving other groups free of such strands, whirling the fibers of the leading group around a vertical axis to mix together the fibers, the strands, and binder thereof, maintaining the groups of fibers separated throughout their full downward travel, collecting the fibers, the dispersed binder of all groups and the fibrous glass strands of the leading group as a pack upon the receiving surface, compressing the pack and setting the dispersed binder to dimensionally stabilize the pack in board form by cohering the fibers throughout the pack and cohering the fibers and the strands in the surface stratum thereof constituting the fibers and strands of the leading group deposited last upon the pack in the movement of the receiving surface.

Claims

1. A method of producing a thermal insulating roofing board of bonded, randomly positioned and spacedly related individual, discontinuous glass fibers with short bundles or strands of multiple glass filaments distributed in intermixed and bonded relation with the individual glass fibers throughout a narrow surface of the board, said method comprising drawing individual fibers from molten glass and directing them downwardly in spaced and randomly positioned relation toward a transversely traveling receiving surface, dividing the descending fibers into separate groups, said groups positioned successively in the direction of travel of the receiving surface, combining a dispersed settable binder with the fibers of each group, combining and intermingling short bundles or strands of definite predetermined lengths and containing hundreds of glass filaments with the individual fibers and dispersed binder of the group of fibers leading the succession of groups in the direction of travel of the receiving surface, while leaving other groups free of such strands, whirling the fibers of the leading group around a vertical axis to mix together the fibers, the strands, and binder thereof, maintaining the groups of fibers separated throughout their full downward travel, collecting the fibers, the dispersed binder of all groups and the fibrous glass strands of the leading group as a pack upon the receiving surface, compressing the pack and setting the dispersed binder to dimensionally stabilize the pack in board form by cohering the fibers throughout the pack and cohering the fibers and the strands in the surface stratum thereof constituting the fibers and strands of the leading group deposited last upon the pack in the movement of the receiving surface.