Industrial asphalt composition

Abstract

This invention is based upon the discovery that a small amount of lime can be incorporated into industrial asphalt to greatly improve its resistance to oxidative hardening cracking and low temperature thermal cracking. The incorporation of a small amount of lime into industrial asphalt accordingly results in products made therewith offering improved service life. For instance, roofing shingles made with such asphalt that contains a small amount of lime will be more resistant to cracking and failure in both hot and cold weather climates. The subject invention more specifically discloses an asphalt roofing shingle having an upper surface and an underside, said asphalt roofing shingle being comprised of a fiber mat which is coated with an asphalt composition, wherein the upper surface of the asphalt roofing shingle includes a layer of roofing granules, wherein the asphalt composition has a softening point which is within the range of 185° F. (85° C.) to 250° F. (121° C.) and a penetration value of at least 15 dmm, and wherein the asphalt composition contains from 0.1 weight percent to 5 weight percent lime. The subject invention further discloses a method for preparing an industrial asphalt comprising (1) heating a base asphalt to a temperature which is within the range of about 100° F. (38° C.) to 400° F. (204° C.) to produce a hot base asphalt, and (2) mixing from 0.1 weight percent to 5 weight percent lime throughout the hot base asphalt while the mixture of hot base asphalt and lime is maintained at a temperature which is within the range of 100° F. (38° C.) to 400° F. (204° C.) to produce the industrial asphalt.

1 . A method for preparing an industrial asphalt comprising (1) heating a base asphalt to a temperature which is within the range of about 100° F. to 400° F. to produce a hot base asphalt, and (2) mixing from 0.1 weight percent to 5 weight percent lime throughout the hot base asphalt while the mixture of hot base asphalt and lime is maintained at a temperature which is within the range of 100° F. to 400° F. to produce the industrial asphalt.  
     
     
         2 . A method as specified in  claim 1  wherein the lime is in the form of solid particles or a solid powder.  
     
     
         3 . A method as specified in  claim 1  wherein the lime is added to the asphalt as an aqueous slurry.  
     
     
         4 . A method as specified in  claim 1  wherein the mixing in step ( 2 ) is fulfilled by mechanical agitation.  
     
     
         5 . A method as specified in  claim 1  wherein the mixing in step ( 2 ) is fulfilled by bubbling an inert gas through the hot lime modified base asphalt.  
     
     
         6 . A method as specified in  claim 1  wherein the lime is mixed into the asphalt in step ( 2 ) for a period of time which is within the range of about 10 minutes to about 4 hours.  
     
     
         7 . A method as specified in  claim 1  wherein the amount of lime added to the hot base asphalt in step ( 2 ) is within the range of 0.5 weight percent to 2 weight percent.  
     
     
         8 . A method for preparing an industrial asphalt comprising (1) heating a base asphalt to a temperature which is within the range of about 100° F. to 400° F. to produce a hot base asphalt, (2) adding from about 0.1 weight percent to about 5 weight percent of a lime compound to the hot base asphalt, (3) mixing the lime compound throughout the hot base asphalt to prepare a lime compound containing base asphalt, (4) heating the lime compound containing base asphalt to a temperature which is within the range of about 400° F. to about 550° F. to produce a hot lime compound containing base asphalt, (5) sparging an oxygen containing gas through the hot lime compound containing base asphalt for a period of time which is sufficient to produce the industrial asphalt.  
     
     
         9 . An industrial asphalt composition comprising asphalt and from 0.1 weight percent to 5 weight percent lime.  
     
     
         10 . An industrial asphalt composition as specified in  claim 9  wherein the lime is present in the asphalt composition at a level which is within the range of 0.5 weight percent to about 2 weight percent.  
     
     
         11 . An industrial asphalt composition as specified in  claim 9  wherein the asphalt has a softening point which is within the range of 185° F. to 250° F., and wherein the asphalt has a penetration value of at least 15 dmm.  
     
     
         12 . An industrial asphalt composition as specified in  claim 9  wherein the industrial asphalt has a softening point which is within the range of 185° F. to 235° F. and wherein the industrial asphalt has a penetration value which is within the range of 15 dmm to 35 dmm.  
     
     
         13 . An industrial asphalt composition as specified in  claim 9  wherein the industrial asphalt has a softening point which is within the range of 190° F. to 220° F. and wherein the industrial asphalt has a penetration value which is within the range of 15 dmm to 25 dmm.  
     
     
         14 . An industrial asphalt as specified in  claim 9  wherein the industrial asphalt is a Type I asphalt which has a softening point of from 135° F. to 151° F. and a penetration of from 18 dmm to 60 dmm at 77° F.  
     
     
         15 . An industrial asphalt as specified in  claim 9  wherein the industrial asphalt is a Type II asphalt which has a softening point of from 158° F. to 176° F. and a penetration of from 18 dmm to 40 dmm at 77° F.  
     
     
         16 . An industrial asphalt as specified in  claim 9  wherein the industrial asphalt is a Type III asphalt which has a softening point of from 185° F. to 205° F. and a penetration of from 15 dmm to 35 dmm at 77° F.  
     
     
         17 . An industrial asphalt as specified in  claim 9  wherein the industrial asphalt is a Type IV asphalt which has a softening point of from 210° F. to 225° F. and a penetration of from 12 dmm to 25 dmm at 77° F.  
     
     
         18 . An industrial asphalt composition as specified in  claim 9  wherein the lime is hydrated lime.  
     
     
         19 . An industrial asphalt as specified in  claim 9  wherein the lime compound is dolomitic normal hydrate.  
     
     
         20 . An industrial asphalt as specified in  claim 9  wherein the lime is a dolomitic pressure hydrate.  
     
     
         21 . An industrial asphalt as specified in  claim 9  wherein the lime is quicklime.  
     
     
         22 . An industrial asphalt as specified in  claim 9  wherein the lime compound is a dolomitic quicklime.  
     
     
         23 . An asphalt roofing shingle having an upper surface and an underside, said asphalt roofing shingle being comprised of a fiber mat which is coated with an asphalt composition, wherein the upper surface of the asphalt roofing shingle includes a layer of roofing granules, wherein the asphalt composition has a softening point which is within the range of 185° F. to 250° F. and a penetration value of at least 15 dmm, and wherein the asphalt composition contains from 0.1 weight percent to 5 weight percent lime.  
     
     
         24 . An asphalt roofing shingle as specified in  claim 23  wherein the industrial asphalt has a softening point which is within the range of 185° F. to 235° F., and wherein the industrial asphalt has a penetration value which is within the range of 15 dmm to 35 dmm.  
     
     
         25 . An asphalt roofing shingle as specified in  claim 23  wherein the industrial asphalt has a softening point which is within the range of 190° F. to 220° F., and wherein the industrial asphalt has a penetration value which is within the range of 15 dmm to 25 dmm.  
     
     
         26 . An asphalt roofing shingle as specified in  claim 23  wherein the lime is present in the asphalt composition at a level which is within the range of 0.5 weight percent to about 2 weight percent.  
     
     
         27 . An asphalt roofing shingle as specified in  claim 23  wherein the lime is hydrated lime.  
     
     
         28 . An asphalt roofing shingle as specified in  claim 23  wherein the fiber mat is comprised of glass fibers.  
     
     
         29 . An asphalt roofing shingle as specified in  claim 23  wherein the fiber mat is comprised of at least one polymeric fiber selected from the group consisting of polyethylene fibers, polypropylene fibers, polyester fibers, nylon fibers, and acrylic fibers.  
     
     
         30 . An asphalt roofing shingle as specified in  claim 23  wherein the lime is dolomitic normal hydrate.  
     
     
         31 . An asphalt roofing shingle as specified in  claim 23  wherein the lime is dolomitic pressure hydrate.  
     
     
         32 . An asphalt roofing shingle as specified in  claim 23  wherein the lime is quicklime.  
     
     
         33 . An asphalt roofing shingle as specified in  claim 23  wherein the lime is dolomitic quicklime.  
     
     
         34 . An asphalt roll roofing membrane that is comprised of a reinforcing mat having an upper side and a lower side wherein said reinforcing mat is coated on its upper surface and its lower surface with an asphalt composition that is comprised of asphalt and from 0.1 weight percent to 5 weight percent lime.  
     
     
         35 . A roofing underlayment which is comprised of an asphalt saturated felt wherein the asphalt contains from 0.1 weight percent to 5 weight percent lime.  
     
     
         36 . A built-up roofing which is comprised of multiple layers of roofing paper or felt that are adhered together with asphalt and which is covered on its upper surface with mineral roofing granules or gravel wherein the asphalt contains from 0.1 to 5 weight percent lime.  
     
     
         37 . An adhesive composition which is comprised of asphalt and of a polymer modifier wherein the asphalt contains from 0.1 to 5 weight percent lime.