CA2216026A1 - Roofing members having improved dimensional stability and related methods - Google Patents

Abstract

A method of reroofing a roof comprises applying laminated recovery boards of the present invention to a roof deck; and, applying a weather protective layer over the recovery boards. The laminated recovery boards comprise foam core (11) selected from the group consisting of polyisocyanurate and polyurethane materials and mixtures thereof; and first and second facers (12, 13), between which the foam core is sandwiched, the facers comprising a polymer sheet containing a reinforcing material selected from the group consisting of glass strands, glass fibers, and mixtures thereof, wherein the polymer sheet is selected from the group consisting of polypropylene and polymer latexes; and, applying a weather protective layer over the laminated recovery boards.

Description

CA 022l6026 l997-09-22 9505031(P.139) ROOFING MEMBERS HAVING IMPROVED DIMENSIONAL STAPILITY
AND RELATED METHODS

TECHNICAL FIELD
This invention relates to a laminated board suitable for use as a recovery board within a roof system. Particularly, the present invention relatesto a laminated board having improved dimensional stability, especially when exposed to extreme environmental conditions including high heat, humidity and moisture.
KACKGROUND OF THE INVENTION
Roof construction in a low-pitched roof generally consists of a roof deck, an insulation barrier above the deck, a weather resistant layer applied tothe insulation layer, and optionally a layer of heat resistant material. The roof 15 deck generally includes materials such as wood, gypsum, concrete, steel, and the like. Above the roof deck, insulation boards are typically applied to provide thermal insulation and a uniform surface to which the weather protective layer is applied. The most common recovery boards are made of woodfiber or extruded polystyrene. Recovery boards can also be made with a variety of core 20 materials that are typically coated with a protective facer that can be either rigid or flexible and is optionally fire or flame-retardant. In a reroofing operation, the roof deck can refer to the existing roof, including the existing insulation and weather resistant layer.
Recovery boards, as they are referred to in reroofing, have been 25 employed where the existing roof is leaking. These boards are generally applied to an existing roof deck assembly to provide a uniform surface when recovering an existing roof. The most common recovery boards are made of woodfiber or extruded polystyrene. The woodfiber is typically coated with a thin layer of asphaltic material on one side, and those recovery boards that are made of 30 polystyrene typically do not contain a facer.
To seal the roof from the elements, recovery boards are typically covered with various materials including molten asphalt, modified bitumen membrane, rubberized asphalt, or an elastomeric composition such as EPDM

CA 022l6026 l997-09-22 9505031(P.139) 2 (ethylenepropylene diene monomer). Not all sealing materials, however, are compatible with each type of recovery board. For example, molten asphalt can not be used with extruded polystyrene. Correct combinations of sealing material and recovery board are known to those skilled in the art. The heat resistant layer of material, which is generally applied directly to the weather resistant layer, can include gravel, river stone, foam or a layer of mastic followed by granules.
Application of the weather protective layer can be accomplished by a number of means, usually dictated by the type of material employed. For example, sheets of a protective membrane can be rolled out over the roof and 10 bonded together by torching or the use of an adhesive.
Although inexpensive and generally in wide use, woodfiber and polystyrene-containing insulation or recovery boards are often ineffective in hot, humid and wet environments. Particularly, woodfiber boards will disintegrate in a wet, humid environment, which is common in a reroof operation. Polystyrene 15 will expand, bow, or distort in similar environments, especially when exposed to the exl~eme heat experienced upon roofs in warmer climates.
The patent literature does include panels and boards used for roofing operations. Built-up roof constructions and the components thereof, for example,are well-known in the art as generally explained in Blanpied, U.S. Pat. No.
20 5,001,005, Dybsky et al., U.S. Pat. No. 4,944,818, and Rosato et al., U.S. Pat.
No. 4,388,366. With regard to insulation boards, Blanpied teaches a rigid foam board comprising a thermosetting plastic foam sandwiched between two facers;
the facer comprising glass fibers, non-glass filler, and non-asphaltic binder.
Likewise, Dybsky et al. teaches a composite roofing substrate panel comprising 25 a core of combustible material such as fibers or foams and a facer of noncombustible material such as glass fibers coated with a bituminous material.
Rosato et al. teaches a laminate insulation board comprising a plastic foam coreand at least one facer sheet forming both a protective layer and a venting meansfor fluids; the facer sheet comprising fine glass fibers bonded together with 30 polyvinyl acetate.
Thus, a need still exists for a recovery board which can be exposed to moisture during installation and remain dimensionally stable while wet and during the eventual evaporation of the moisture. Use of a composite which CA 022l6026 l997-09-22 9505031(P.139) 3 contains isocyanurate and/or urethane foam between facers that comprise a polymer, such as polypropylene, polymer latexes and the like, reinforced with glass strands or glass fibers and optionally a filler material, such as calcium carbonate, clay, mica and the like, makes the composite of the present inventiondimensionally stable and relatively insensitive to moisture in reroofing.

SUMMARY OF INVENTION
It is therefore, an object of the present invention to provide a relatively inexpensive laminated board, particularly for use in reroofing, that is 10 dimensionally stable in hot, humid and wet conditions.
It is another object of the present invention to provide a laminated board having a facing that can withstand adhesive application of the weather protective layer onto the roof.
It is another object of the present invention to provide a laminated 15 board having sufficient integrity to patch or cover the roof;
It is another object of the present invention to provide a laminated board providing a good base for subsequent application of the final layer or roof covering and, which is compatible with the latter and the respective means of application.
It is yet another object of the present invention to provide a method for reroofing utilizing laminated board.
It is still another object to provide a method for manufacturing laminated boards of the present invention.
At least one or more of the foregoing objects of the present invention 25 together with the advantages thereof over the existing asphalt materials, which shall become apparent from the specification that follows, are accomplished by the invention as hereinafter described and claimed.
In general the present invention provides a method of reroofing a roof comprising applying laminated recovery boards to a roof deck, the recovery 30 boards comprising a foam core selected from the group consisting of polyisocyanurate and polyurethane materials and mixtures thereof; and first and second facers, between which the foam core is sandwiched, the facers comprising a polymer sheet containing a reinforcing material selected from the CA 022l6026 l997-09-22 9505031(P.139) 4 group consisting of glass strands, glass fibers, and mixtures thereof, wherein the polymer sheet is selected from the group consisting of polypropylene and polymer latexes; and, applying a weather protective layer over the laminated recovery boards.

BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a roofing member in accordance with the present invention; and Fig. 2 is a schematic view of apparatus employed to manufacture 10 roofing members of the present invention.

. ~c.~ E, EMBODIMENT FOR CARRYING OUT THE INVENTION
The present invention is directed toward a laminated board or roofing member that is used to reroof an existing roof. The roofing member is applied 15 to a roof deck which is substantially flat or low-pitched, and which can be newly constructed, or which is exposed by the removal of old roofing or, which is an existing roof system in suitable condition for recovering. Inasmuch as roof decks are known and do not constitute part of the present invention, other than as a substrate or base upon which the roofing members are laid, further detail is not20 necessary. Although the roofing members can be utilized as part of new roof installations, the boards are specifically designed for reroof operations.
One common problem in most if not all reroof installations is a wet and often somewhat deteriorated roof or substrate. Typically, when a leak is noticed, and certainly when it is deemed necessary to repair, use of the laminate 25 board of the present invention provides an inexpensive and facile means of reroofing either the affected area or more commonly, the entire roof. Thus, the roofing member must have sufficient integrity to patch or cover the roof; it must provide a good base for subsequent application of the final layer or covering, such as an EPDM roofing membrane; and, it must be compatible with the latter 30 and the respective means of application.
In other words, a board placed over the old roof to act as a substrate for the new waterproof membrane will typically become wet. Existing boards made from wood fiber, extruded polystyrene will distort and/or deteriorate, CA 022l6026 l997-09-22 9505031(P.139) 5 necessitating further reroofing efforts. Existing boards manufactured from isocyanurate foams would fare better, except the existing state of the art has been to utilize facers that also absorb water, causing untimely failure of the board in certain situations where moisture is encountered. Existing facers contain organic felt materials, which provide a wicking action through the facer.
While such problems can be minimized by drying the roof before repair, or by waiting for it to dry, this is not often practical.
Other facer materials have employed glass and fiberglass reinforcement with urea/formaldehyde resin as a binder; however, these "all glass" facers as 10 they are sometimes referred, are notorious for a condition known as "strike through" during the manufacturing process. When this occurs, the foam can more readily penetrate through the facer and reach the lamination equipment, causing it to freeze up as well as creating other manufacturing problems. This weakness has been somewhat attributed to the industries' usage of polymers as 15 bonding agents that are porous to permit venting of gases and vapors. Polyvinyl acetate, for example, is often utilized as the bonding agent to provide such porosity in facers reinforced with glass.
The laminated board according to the present invention is best described with reference to Fig. 1. Such a board is indicated generally by the 20 numeral 10 and comprises a foam core 11 sandwiched between a lower facer 12 and an upper facer 13. The boards 10 are generally from about 0.50 to about 4 inches thick, more preferably from about 0.5 to about 1.5 inch thick, and mostpreferably from about 0.5 to about 1 inch thick; and can be fabricated in various dimensions depending on the intended application. Boards fabricated into sheets 25 4 feet wide and 8 feet long are best suited for compatibility in the building trade.
The foam core 11 can be polyisocyanurate, urethane, or mixtures thereof. The foam core is generally of standard production and generally includes those having an index of about 250. Particularly, when polyisocyanuratefoam is employed, those having an index above 200 are preferred; and when urethane is employed, an index above 120 is preferred. Further, mixed foams can be employed, such as a mixture of polyisocyanurate and urethane.
The lower facer 12 and upper facer 13 are generally of the same or similar compositions, but embodiments within this invention can include an upper CA 022l6026 l997-09-22 9505031(P.139) 6 and lower facer comprising different compositions suited for a particular use.
The upper and lower facers of the present invention comprise reinforced polymer material, thus forming a polymer sheet. Particularly, the polymer material can include polypropylene, polymer latexes, or mixtures thereof. Examples of the 5 latter include styrene-butadiene rubber (SBR), polyvinyl chloride, polyvinyl alcohol and mixtures thereof. Thicknesses of the facers typically range between about 0.01 and 0.15 inch.
The polymer material also includes reinforcing materials such as glass strands, glass fibers, or mixtures thereof. Amounts of such reinforcing materials range from about 100 to about 10,000 parts by weight, based upon 100 parts by weight of the polymer selected to form the facer. Furthermore, the reinforced polymer material can optionally include fillers such as clay, mica, talc, limestone (calcium carbonate), gypsum (calcium sulfate), aluminum trihydrate, antimony oxide, cellulose fibers, plastic polymer fibers, and mixtures thereof. Amounts of such fillers range from about 0 to about 5,000 parts by weight, based upon 100 parts by weight of the polymer selected to form the facer.
The facers of the present invention have been found to impart weatherability and durability to laminated boards used as roofing substrates within a roof system. Particularly, the facers of the present invention have been 20 found to provide dimensional stability to the boards, inhibiting the boards from distorting under high heat and moisture. In addition to dimensional stability, the facers protect the foam from moisture, as well as from penetration. Because of these advantages, the facers of the present invention have been found to be particularly useful with recovery boards because the environment commonly 25 encountered in a reroof operation is hot, humid and often wet. Moreover, the optional fillers add strength to the facer and provide the facer with a rugged appearance.
The laminated boards 10 are typically applied to the roof deck in staggered parallel adjacent courses that abut one another. The boards are 30 generally fastened to the deck via nails or an adhesive, although other means of securing insulation board to roof deck are common in the art. Once the laminated or recovery board of the present invention has been applied to a roof deck, the roof is completed by covering the substrate with a weather protective CA 022l6026 l997-09-22 9505031(P.139) 7 layer. The protective layer can include any system where the temperature of application will not melt the polymer or latex. Accordingly, means of attaching the roof covering to the recover board should not exceed 100~C, which essentially rules out molten asphalt. Useful systems typically include various 5 types of modified bitumen or EPDM roofing membranes, or any other appropriate protective layers known in the art. In ballasted roofs, this protective layer is then covered with gravel, river stone or mixtures thereof; wherein the weight of the river stone serves a second function which is to secure the protective layer andunderlying materials, such as the recovery boards, to the roof deck.
While the boards may be manufactured in a batch process, a continuous, on-line process is preferred as such a process is both efficient andeconomical. With reference to Fig. 2, a continuous process is schematically depicted in conjunction with apparatus 20. The apparatus provides lower and upper spools, 21 and 22 respectively, for lower and upper facers 12 and 13, which are positioned for feeding into a laminator assembly, generally 24, which comprises lower and upper continuous belts or treads, 25 and 26, reeved around a series of rolls 28, several of which are driven. The lower or bottom facer 12,is first fed into the laminator 24, resting on belt 26. Immediately above the facer 12, as it enters the laminator 24, is a foam mixhead 30. The mixhead 30 is fed from reservoirs 31 and 32, or whatever number are required by the polymer foam composition selected. Typically, there are two mixheads per laminator.
Where the desired foam is a polyurethane, for instance, reservoir 31 can providethe isocyanate components and reservoir 32 the polyol components. The resin materials from these reservoirs are fed through metering pumps 33 and 34 and through appropriate conduits 35 into the mixhead 30, where upon contact, reaction commences to form the polymer foam.
The mixhead 30 then supplies an appropriate mixture 36 of resins from the reservoirs 31 and 32, as well as an appropriately metered amount, onto the surface of the moving facer 12. Subsequently, and slightly downstream of the mixhead 30, the upper facer 13 is fed into the laminator 24, passing around a feed roller 38, which positions the facer 13 against the upper belt 26. As the facers and deposited foamable composition are conveyed, the latter rises, as depicted at 40, until the upper facer 13 is in complete contact with the upper CA 022l6026 l997-09-22 9505031(P.139) 8 belt 26. It is to be appreciated that the belts 25 and 26 are adjustable to accommodate the desired thicknesses of board 10.
After the foaming has completed, the intermediate product, indicated by the numeral 42, is heated to effect curing of the polymer. This is accomplished by appropriately located heaters, generally 44, or by passage through an oven (not shown). After heating for the appropriate time (residence) and temperature, the product emerges from the laminator and is cut to length to produce the boards 10. Such cutting is within the skill of the art, including flying cut-off saws and the like, which provide desired dimensions without interruption10 of the apparatus 20. While lengths can be varied at will on such apparatus, the widths of the boards 10 can subsequently be trimmed to size in a separate operation, as necessary. It is also possible to provide sidewalls (not shown) inconjunction with the laminator 24, to define the desired widths as the polymer is foaming within the laminator.
EXAMPLES
In order to demonstrate the practice of the present invention, four (4) types of construction board were selected. One board included woodfiber such as that sold by Georgia Pacific under the tradename Sturdy Top, having a 45 mil 20 EPDM facer on one side. A second board included extruded polystyrene such as that sold by Dow Chemical Company under the tradename Recover Mate. The third board, fabricated according to the present invention, included a polyisocyanurate foam core having identical upper and lower facers comprising polypropylene reinforced with fiberglass, the fiberglass comprising about 85 25 percent by weight of the facer. The fourth board is that sold by Atlas Roofing Corp., and is believed to be that described in U.S. Patent No. 5,001,005, and includes a polyisocyanurate foam core having upper and lower facers comprising polymer latex reinforced with fiberglass and non-glass fillers. Each board was 0.5 inch in thickness.
Each type of board was then subject to various testing. The first test was a water absorption test similar to that described in ASTM C-209. Consistent with this test, each board was exposed to water for 120 hours and the percent weight gain was determined and reported as described in Table 1.

CA 022l6026 l997-09-22 9505031(P.139) 9 TABLE I
PERCENT WEIGHT GAIN
Ex. No BOARD WEIGHT GAIN %
Woodfiber (EPDM Facer) 116 2 Polystyrene (No Facer)0 (approx.) 3 .olyi o~yanurate 33 (rei~ rce.l polypropylene) 4 .olyi _~ranurate 30 (reil~, rc~l polymer latex) Each of the above described boards was also tested for flexural strength as per ASTM C-203, Method 1, Procedure A. Measurements based on machine direction (MD) and cross machine direction (CMD) were taken when each board was dry and after 24 hours of water exposure per the above test in 15 accordance with ASTM C-209. The results from the test are represented in Table Il. Values are in terms of pounds per square inch.

TABLE ll FLEXURAL STRENGTH
Ex. No. FLEXURAL STRENGTH DRY DRY WET WET
MD CMD MD CMD
Woodfiber (EPDM FACER) 28.6 25.6 14.7 13.2 2 Polystyrene (No facer) 17.7 11.0 13.4 9.1 3 Folyi ~cyanurate 21.0 15.2 15.1 15.1 (rein~, rc~.l polypropylene) 4 Polyisocyanurate 24.0 19.3 20.6 15.6 (reinfar~.l paly., - latex) Boards, as described above were also subjected to wind uplift testing.

The wind uplift tests were performed employing a standard 5' x 9' wind uplift table. The four bards subjected to testing included a wood fiber board of 0.5 CA 022l6026 l997-09-22 9505031(P.139) 10 inch thickness having a 45 mil EPDM protective coating, an extruded polystyrene board of 0.5 inch thickness, a polypropylene board of 0.5 inch thickness having a glass fiber reinforced facer, and a polymer latex board of 0.5 inch thickness.Each board was mechanically fastened to the wind uplift table employing one 5 fastener and a 2' x 2' fastening plate having a diamond-in-square fastening pattern.
Finally, boards as described above were tested at an outdoor test site in Miami, Florida, for at least four months, between mid-February and mid-July.
The boards were placed upon a woodfiber/steel roof deck, and mechanically 10 attached in a staggered parallel pattern so that the adjacent edges would abut one another. A protective layer of EPDM was placed upon the boards. Water was liberally applied to the roof deck and the recovery boards prior to applyingthe EPDM layer to simulate a wet roof recovery situation.
The Miami conditions during this period were consistent with 15 conditions normally experienced during that time of the year, which is generally very hot, humid and wet. Pictures of the boards were taken before and after the testing period and the observations recorded. The observations of the tests are presented in TABLE IV. In general, the woodfiber became wet, soft and mushy with loss of strength in all directions; heavy build-up of mildews and molds was20 also observed. The extruded polystyrene did not become wet but experienced expansion that led to buckling of the board, which typically leads to ponding above the EPDM layer. In previous experiments, polystyrene boards experienced early (within several hours of application) post expansion or excessive shrinkage, which was typically greater than 1/4 of an inch in either direction. Any of these 25 conditions can compromise the integrity of the protective EPDM layer, resulting in a leaky roof. The two polyisocyanurate boards absorbed minimal amounts of water and showed no evidence of expansion or shrinkage.

CA 022l6026 l997-09-22 9505031(P.139) 1 1 TABLE IV

Recover Board Type Observations After Four Months Exposure Woodfiber (1/2") ~ wet ~ soft ~ mushy (easily penetrated) ~ Ioss of flexural, tensile and compressive strength ~ presence of black and white mildew and various molds Extruded Polystyrene (%") ~ Buckling between fastened areas as a (more than one experiment) result of expansion ~ Shrinkage (greater than 1/4", more at times) ~ Early post expansion ~ no evidence of water absorption Polyisocyanurate with ~ Slight absorption of water polypropylene/fiberglass facer ~ no evidence of expansion or shrinkage Polyisocyanurate with latex ~ Slight absorption of water polymer/fiberglass filler facer ~ no evidence of expansion or shrinkage Thus it should be evident that the method of the present invention is highly effective for reroofing. The method for reroofing can be practiced with 15 the variety of boards 10 that fall within the scope of the present invention.Based upon the foregoing disclosure, it should now be apparent that the use of the laminated boards described herein will carry out the objects set forth hereinabove. It is, therefore, to be understood that any variations evident fall within the scope of the claimed invention and thus, the selection of specific 20 component elements can be determined without departing from the spirit of theinvention herein disclosed and described. In particular, boards according to thepresent invention are not necessarily limited to those having a isocyanurate or polyurethane foam core. Moreover, as noted hereinabove, the composition of the polymer facer can be varied, particularly with the use of the optional fillers.
25 Thus, the scope of the invention shall include all modifications and variations that may fall within the scope of the attached claims.

Claims (10)

1. A method of reroofing a roof comprising:
applying laminated recovery boards to a roof deck, the recovery boards comprising a foam core selected from the group consisting of polyisocyanurate polyurethane and mixtures thereof; and first and second facers, between which the foam core is sandwiched, said facers comprising a polymer sheet containing reinforcing material selected from the group consisting of glass strands, glass fibers, and mixtures thereof, wherein said polymer sheet is selected from the group consisting of polypropylene and polymer latexes; and applying a weather protective layer over said recovery boards.

2. A method of reroofing a roof, as set forth in claim 1, wherein said facers are essentially devoid of any organic felt materials.

3. A method of reroofing a roof, as set forth in claim 1, wherein said facer further comprises a filler selected from the group consisting of clay, mica, talc, limestone, gypsum, aluminum trihydrate, antimony oxide, cellulose fibers, plastic polymer fibers, and mixtures thereof.

4. A method of reroofing a roof, as set forth in claim 3, wherein the filler comprises from about 0 to about 5,000 parts by weight per 100 parts by weight of said polymer sheet.

5. A method of reroofing a roof, as set forth in claim 1, wherein the foam core has an index of about 250.

6. A method of reroofing a roof, as set forth in claim 1, wherein the polymerlatexes are selected from the group consisting of styrene-butadiene rubber, polyvinyl chloride, polyvinyl alcohol and mixtures thereof.

7. A method of reroofing a roof, as set forth in claim 1, wherein said first and second facers have a thickness in the range between about 0.01 inch and about 0.15 inch.

8. A method of reroofing a roof, as set forth in claim 1, wherein said step of applying laminated recovery boards to a roof deck comprises placing the laminated recovery boards in staggered parallel adjacent courses that abut one another.

9. A method of reroofing a roof, as set forth in claim 1, wherein the weatherprotective layer is selected from the group consisting of modified bitumen, and EPDM roofing membranes.

10. A method of reroofing a roof, as set forth in claim 1, further comprising the step of applying another layer onto the weather protective layer selected from the group consisting of gravel, riverstone, and mixtures thereof.