Patent Application
20080085954
Referring now to disclosure set forth below which describes preferred embodiments of the invention only and is not for the purpose of limiting the same, there is proved a bitumen base adhesive that releases little, if any, volatiles during the application and curing of the adhesive. The bitumen base adhesive includes asphalt and/or coal tar and 2) silylated polymer and/or silyl-terminated polymer. Non-limiting examples of the bitumen base adhesive are set forth below:
As set forth in Example E, the asphalt was formed by a blend of PDA hard base and Roofing Flux. In the examples set forth above, MS Polymer S203H and MS Polymer S303H are polymers that include silyl-terminated polyether. These two products are available from Kaneka Corporation. As can be appreciated, other or additional silyl-terminated polymers can be used (e.g., MAX923, MAX951, SAX350, SAT030, SAT010, SAX400, etc.). Diethylhexyl phthalate is a plasticizer. As can be appreciated, other or additional plasticizers can be used (dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, etc.). A-1120 is an aminosilane offered by GE Chemical. The aminosilane is used as an adhesion promoter. As can be appreciated, other or additional aminosilanes can be used (e.g., A-2120, etc.). Lowinox 22M46 is a non-discoloring, non-staining sterically hindered bis-phenol that is offered by Great Lakes Polymer Additives. Lowinox 22M46 is used as an antioxidant. As can be appreciated, other or additional antioxidants can be used. Dibutyltin Acetylacetonate is used as an organotin catalyst. This compound is available from Harwick Standard Distribution. As can be appreciated, other or additional catalysts can be used (e.g., UL-2 by GE, UL-4 by GE, SUL-4 by GE, SUL-11A by GE, UL-22 by GE, UL-24 by GE, UL-28 by GE, UL-29 by GE, UL-32 by GE, UL-38 by GE, etc.). A-171 is a vinyl silane offered by GE Chemical. A-171 is used as a dehydration agent. As can be appreciated, other or additional dehydration agents can be used (e.g., A-151, A-2171, etc.). Calcium Carbonate is used as a filler and reinforcing pigment. As can be appreciated, other or additional fillers and/or pigments can be used (e.g., carbon black, silica, calcium phosphate, dolomite, titanium dioxide, etc.) Crayvallac Super is a polyamide offered by Cray Valley. Crayvallac Super is used as a thixotropic agent. As can be appreciated, other or additional thixotropic agents can be used (e.g., Crayvallac Ultra, Crayvallac Extra, etc.).
In addition to the components identified in the non-limiting examples, additional components can be included in the bitumen based adhesive. Such additional components include, but are not limited to, compatibilizer, tackifier, stabilizer, antioxidant, ultraviolet absorber, metal deactivator, light stabilizer, amine type radical chain inhibitor, phosphorus-containing peroxide decomposer, lubricant, foaming agent, anti-foaming agent flame retardant and/or antistatic agent.
The bitumen based adhesive is prepared by first heating the bitumen material and then mixing the silylated polymer and/or silyl-terminated polymer in the bitumen. When a plasticizer is included in the bitumen based adhesive, the plasticizer is typically mixed with the bitumen prior to the addition of the silylated polymer and/or silyl-terminated polymer. The manufacture of a bitumen based adhesive in accordance with Example E is set forth as follows. An asphalt having a softening point of about 140-160° F., and typically about 145-155° F. is prepared. The asphalt can be prepared by mixing together hard asphalt and roofing flux in a weight percent ratio of about 2-5:1, and typically about 2.5-3.5:1. Generally the asphalt is stirred and/or mixed for about 5-75 minutes at a temperature of about 170-190° F. After the hard asphalt and roofing flux are blended together to form an asphalt having the desired softening point or a single type of asphalt having the desired softening point has been stirred and melted, the asphalt is mixed with about an equal amount of diethylhexyl phthalate plasticizer. Typically the weight percent ratio plasticizer to asphalt in the mixture is about 0.8-1.2:1, and more typically about 0.95-1.05:1. The mixture is mixed together under sufficient heat to as to maintain the mixture above the softening point of the mixture. Generally the mixture is mixed at a temperature of about 170-190° F. for about 5-100 minutes. The mixture can be mixed under a vacuum; however, this is not required. Once the plasticizer and asphalt have been properly mixed to form an asphalt based mixture, the dried calcium carbonate and any remaining plasticizer is added to the asphalt based mixture. The calcium carbonate should be sufficiently dried to eliminate most of the moisture. This mixture is then heated to about 165-180° F. and stirred under a vacuum for about 20-200 minutes. The stirring of the mixture under a vacuum facilitates in eliminating water from the mixture. Once the mixing of these components is completed, the mixture is cooled to about 130-160° F. and the antioxidant and the thixotropic agent are then added to the mixture. The mixture is again mixed under a vacuum for about 30 minutes to facilitate in the removal of water from the mixture. Once the mixture has been properly mixed, the silyl-terminated polyether polymer is added to the mixture and then mixed under a vacuum at about 110-130° F. After this mixing step has been completed, the dehydration agent and adhesion promoter are added to the mixture and mixed for about 2-100 minutes under a vacuum. The catalyst is then added to the mixture and mixed for about 2-30 minutes under a vacuum. The formed bitumen base adhesive is then sealed in a container in a nitrogen environment so as to inhibit or prevent the introduction of moisture into the container prior to sealing the container.
The bitumen based adhesive of the present invention is a low volatile formulation that releases little, if any, volatiles during the curing of the adhesive. As such, the bitumen based adhesive is more environmentally friendly. The bitumen based adhesive is particularly formulated for use on roofing systems; however, the bitumen based adhesive can be on other building structures and/or used in other applications that require adhesives.
In one non-limiting application, the bitumen based adhesive is used on a low slope roof structure. The top of the roofing structure can include a metal surface, preexisting roof membrane, vinyl surface, one or more layers of insulation, etc. Typically the top of the roofing structure is generally flat prior to the application of the bitumen base adhesive; however, this is not required. The top of the roof structure can be cleaned of debris, loose materials, etc. to facilitate in the adhesion provided by the bitumen based adhesive.
Once the top of the roof surface has been prepared, the bitumen based adhesive is then applied to the roof surface. The bitumen based adhesive can have a viscosity that enables the adhesive to be sprayed of mopped over the desired top surface of the roof surface. Alternatively, the bitumen based adhesive can be applied in discrete areas on the roof surface (e.g., applied in spaced beads or strips on the roof surface, etc.).
After the bitumen based adhesive is applied to the roof surface, a single or multiple ply roof membrane (e.g., SBS base sheet, SBS cap sheet, ethylene propylene dimer (EPDM) sheet, polyvinyl chloride (PVC) sheet, polyisobutylene (PIB) sheet, thermoplastic polyolefin (TPO) sheet, etc.), an insulation layer or the like can then be applied to the roof surface. The roof membrane can include a fleece material to facilitate in the bonding of the roof membrane to the bitumen based adhesive; however, this is not required. After the roof membrane or insulation layer is applied to the bitumen based adhesive, the adhesive is allowed to cure at ambient temperatures. The natural moisture in the air combination with the catalyst in the adhesive will promote the substantially complete curing of the adhesive in less than about 3 days, and typically about 0.5-48 hours; however, longer or shorter curing times can occur in certain environments and/or applications of the adhesive.
The bitumen based adhesive of the present invention generates little, if any, toxic vapors during the application or curing of the adhesive. The bitumen based adhesive does not require the immediate application of a roof membrane or insulation layer after the application of the adhesive to a roof surface as compared to existing polyurethane type adhesives. The bitumen based adhesive can be used in normal environments, in relatively low temperature environments (e.g., 35-45° F.), or in relatively high temperature environments (e.g., above 100° F.). The viscosity of the bitumen based adhesive can be adjusted depending a particular application. Typically the viscosity of the bitumen based adhesive is about 20,000-500,000 centipoise (Brookfield RVT, #4 Spindle, 2.5 rpm).
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the constructions set forth without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. The invention has been described with reference to preferred and alternate embodiments. Modifications and alterations will become apparent to those skilled in the art upon reading and understanding the detailed discussion of the invention provided herein. This invention is intended to include all such modifications and alterations insofar as they come within the scope of the present invention. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween.
