Stock material or miscellaneous articles – Composite – Of bituminous or tarry residue
Reexamination Certificate
2002-04-03
2004-03-23
Szekely, Peter (Department: 1714)
Stock material or miscellaneous articles
Composite
Of bituminous or tarry residue
C428S147000, C428S3550BL
Reexamination Certificate
active
06709760
ABSTRACT:
BACKGROUND OF INVENTION
It is known to use adhesives to provide a bond between shingles on a roof. Some shingle adhesives are made with blends of asphalt and polymer. During a typical shingle manufacturing process, a pattern of adhesive is applied to the headlap portion of the shingles, so that the tab portion of the subsequently laid course of shingles on the roof will adhere to the headlap portion of the lower course. The adhesive bond helps to prevent wind uplift of the shingles on the roof. It is also known to use adhesives to provide a bond between overlay and underlay portions of a laminated shingle.
U.S. Pat. No. 5,278,207 to Kluttz discloses a composition which may be used as an adhesive on a roofing material. The composition includes asphalt, a polyfunctional amine having at least two amino groups, a polymer such as SBS elastomer, and a crosslinker such as sulfur. The polyfunctional amine is said to be critical to prevent separation of the polymer from the asphalt. There is no suggestion to use a phenolic resin or a phenol-aldehyde resin as a crosslinker in a shingle adhesive.
U.S. Pat. No. 5,256,710 to Krivohlavek discloses a composition including an asphalt, a polymer, and a crosslinker which is either a phenolic resin or a phenol-aldehyde resin. There is no suggestion to use the composition as a shingle adhesive or other type of adhesive.
U.S. Pat. No. 5,270,361 to Duong et al. discloses a composition made from asphalt, natural or synthetic rubber, and selenium as a crosslinker. The patent states that the composition can be used for paving or shingles, but there is no suggestion to use the composition as a shingle adhesive or other type of adhesive.
It would be desirable to provide an improved shingle adhesive having consistency of performance, heat stability, ability to be handled in bulk, flexibility in the choice of asphalt used, and resistance to flattening under the pressure exerted by stacked shingles.
SUMMARY OF INVENTION
The above objects as well as others not specifically enumerated are achieved by an improved adhesive for a roof covering in accordance with the present invention. The adhesive comprises asphalt, polymer and crosslinker. In a first embodiment of the invention, the crosslinker is a phenolic resin or a phenol-aldehyde resin.
In a second embodiment, the adhesive comprises asphalt, polymer and crosslinker, and it excludes polyfunctional amine having at least two amino groups.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.
DETAILED DESCRIPTION
The present invention uses crosslinking technology to create a modified asphalt adhesive having desirable properties for use on roof coverings such as shingles. In particular, the adhesive has excellent compatibility between the asphalt and the polymer, and excellent thermal stability at elevated temperatures. These attributes improve the consistency of performance of the adhesive, allow for bulk transport of the adhesive, and increase the number of asphalts that are usable in the adhesive. The adhesive also has the ability to maintain its shape under the high pressure exerted by stacked shingles. The adhesive retains good bond strength at low temperatures, so that it meets the needs of shingles in cold climates.
The adhesive includes an asphalt, a polymer and a crosslinker. It has been found that an adhesive having the desired properties can be achieved by the choice of a suitable crosslinker and polymer. This contrasts with the above-mentioned Kluttz patent, which states that a particular polyfunctional amine is critical to prevent separation of the polymer from the asphalt. The adhesive of the present invention has excellent compatibility so that it is highly resistant to separation even without the addition of a polyfunctional amine.
The asphalt for use in the adhesive can be either a naturally occurring asphalt or a manufactured asphalt, such as an asphalt produced by refining petroleum or by other known means. Mixtures of different asphalts can also be used. Advantageously, the improved compatibility between the asphalt and the polymer allows increased flexibility in the type of asphalt used in the adhesive. Preferably, the asphalt is a paving grade asphalt or a roofing flux, or a blend of one of these with a solvent extracted asphalt such as a propane deasphalted asphalt (“PDA”). In a particular embodiment, the asphalt is a blend of paving grade asphalt and PDA.
The polymer for use in the adhesive can be any polymer suitable for combining with the asphalt and crosslinker to provide an adhesive having the desired properties. Mixtures of different polymers can also be used. Preferably, the polymer has double bonds which provide bonding sites for the crosslinker. Also preferably, the polymer is a thermoplastic elastomer such as a block copolymer, usually triblock (A—B—A), and either linear or radial in structure. Either block, A or B, may comprise more than one monomer. Preferred are those triblock copolymers having styrene or polystyrene as the “A” block or end block units. Suitable elastomers include thermoplastic rubbers of styrene-butadiene-styrene (S—B—S) and styrene-isoprene-styrene (S—I—S) block copolymers. Suitable elastomers are commercially available from Kraton Polymers (Houston, Tex.) as KRATON™ thermoplastic rubbers, KRATON D grade. Most preferred is KRATON D-4158 (S—B—S) thermoplastic rubber, a radial block copolymer which contains paraffinic oil as an extender.
The crosslinker for use in the adhesive can be any crosslinker suitable for combining with the asphalt and polymer to provide an adhesive having the desired properties. Mixtures of different crosslinkers can also be used. Some examples of suitable crosslinkers include sulfur crosslinkers and silane coupling agents such as those available from Harwick Chemical Corp., Akron, Ohio under the trade names Harwick DSC-45 (tetrasulfide organo-functional group), DSC-25 (mercapto) and DSC-30 (polysulfide). A highly preferred crosslinker for use in the adhesive is a phenolic resin or a phenol-aldehyde resin, such as disclosed in U.S. Pat. No. 5,256,710 to Krivohlavek, issued Oct. 26, 1993 (incorporated by reference herein). A crosslinker as described in the Krivohlavek patent is commercially available as BUTAPHALT™ from TexPar Energy, Sandy, Utah. BUTAPHALT was registered in 1997 to Asphalt Technology and Consulting, Inc., Oklahoma (Registration No. 2040669).
The adhesive can optionally include other ingredients commonly used in shingle adhesives, in concentrations taught in the art, such as fillers, stabilizers, antioxidants, pigments, and solvents.
The composition of the adhesive will often vary depending on the use of the adhesive. When the adhesive is used as a sealant for three-tab shingles, preferably the adhesive comprises, by weight, about 85% to about 95% asphalt, about 5% to about 15% polymer and about 0.05% to about 2% crosslinker. Typically, the adhesive comprises about 88% to about 94% asphalt, about 6% to about 12% polymer and about 0.05% to about 1% crosslinker. In a particular embodiment, the adhesive comprises less than 9% polymer and greater than 0.1% crosslinker. When the adhesive is used as a laminating adhesive to make laminated shingles, preferably the adhesive comprises, by weight, about 90% to about 97% asphalt, about 3% to about 10% polymer and about 0.05% to about 1% crosslinker.
An example of a preferred adhesive for use as a sealant for three-tab shingles has the following composition:92% Asphalt (blend of paving asphalt and PDA) 8% KRATON, 41580.2% BUTAPHALT. Conventional mixing or blending techniques can be used to make the adhesive. Typically, the ingredients are mixed for at least about four hours. Generally, throughout the mixing, the temperature is desirably maintained from about 260° F. to about 360° F. The adhesive is either shipped and used in bulk without cooling, or cooled in packages and then melted for application to shingles or other
Jones David R.
Keating Jay W.
Trumbore David C.
Dottavio James J.
Eckert Inger H.
Owens Corning Fiberglas Technology Inc.
Szekely Peter
LandOfFree
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