Active Polymer Modification of Bitumen for Use in Roofing Materials

Abstract

A modified bitumen consisting of a polyurethane wherein the polyisocyanate or polyisocyanate-dominated polyurethane prepolymer (or prepolymers) is first reacted with the bitumen to take advantage of the bitumen's hydroxyl and amine functionality and form an isocyanate-bitumen adduct to form a weatherproofing product.

Claims

1-20. (canceled)

21. A method for forming an actively modified polymer-modified bitumen material, said method comprises: providing 25-75 wt. % of a first component comprising bitumen, coal tar, or combinations thereof; providing 1-49% wt. % of a second component comprising polyisocyanate compound and polyol; and, adding said second component to said first component to form a mixture and to allow said second component to react with hydroxyl functional groups of said first component to form said bitumen material, a content of said polyol in said mixture creating a NCO/OH equivalent ratio of at least 2:1 in said mixture.

22. The method as defined in claim 21, said method further includes the step of adding additional polyol to said after mixture to ensure that essentially no further isocyanates are being reacted in said mixture.

23. The method as defined in claim 21, wherein said NCO/OH equivalent ratio is 2:1 to 15:1.

24. The method as defined in claim 21, wherein said NCO/OH equivalent ratio is 2:1 to 7:1.

25. The method as defined in claim 21, wherein said NCO/OH equivalent ratio is 3:1 to 6:1.

26. The method as defined in claim 21, wherein said NCO/OH equivalent ratio is 4.5 to 5:1.

27. The method as defined in claim 21, wherein said polyol includes a molecular weight compound of 1000-5000 molecular weight.

28. The method as defined in claim 21, wherein said polyol includes a molecular weight compound of 1000-3000 molecular weight.

29. The method as defined in claim 21, wherein said method further includes the step of adding a filler to said first and second component, said filler constituting 1-66 wt. % of said bitumen material.

30. The method as defined in claim 29, wherein said filler includes one or more compounds selected from the group consisting of calcium carbonate, talc, ammonium polyphosphate, alumina trihydrate, and Mg(OH).sub.2.

31. The method as defined in claim 30, wherein said filler includes calcium carbonate, ammonium polyphosphate, and alumina trihydrate, a content of said calcium carbonate is 5-40 wt. %, a content of said ammonium polyphosphate is 0.1-5 wt. %, a content of said alumina trihydrate is 0.5-20 wt. %.

32. The method as defined in claim 21, wherein a weight percent of said first component is greater than a weight percent of said second component.

33. The method as defined in claim 21, wherein said first component is in a molten state prior to said addition of said second component.

34. The method as defined in claim 21, wherein a weight ratio of said second component to said first component is 0.05-0.7:1.

35. The method as defined in claim 21, wherein said method further includes the step of adding a catalyst to said first and second component.

36. The method as defined in claim 21, wherein said bitumen material comprises 30-70 wt. % of said first component and 4-20 wt. % of said second component.

37. The method as defined in claim 21, wherein said bitumen material comprises 40-60 wt. % of said first component and 4-20 wt. % of said second component.

38. The method as defined in claim 21, wherein said polyol includes at least one compound selected from the group consisting of propylene glycol, polycarbonate diol, polybutadiene glycols, and polybutadiene polyols.

39. The method as defined in claim 21, wherein said polyol includes at least two compounds selected from the group consisting of propylene glycol, polycarbonate diol, polybutadiene glycols, and polybutadiene polyols.

40. The method as defined in claim 21, wherein said polyol includes at least three compounds selected from the group consisting of propylene glycol, polycarbonate diol, polybutadiene glycols, and polybutadiene polyols.

41. The method as defined in claim 21, wherein said polyol includes propylene glycol and polycarbonate diol.

42. The formulation as defined in claim 21, wherein said polyol includes at least three compounds selected from the group consisting of dipropylene glycol, propylene glycol, polycarbonate diol, polybutadiene glycol, and polybutadiene polyol.

43. The formulation as defined in claim 21, wherein said polyol includes at least two compounds selected from the group consisting of hydroxy-terminated polybutadiene, linear hydroxy-terminated polybutadiene, and polycarbonate diol.

44. The formulation as defined in claim 21, wherein said polyol includes hydroxy-terminated polybutadiene, linear hydroxy-terminated polybutadiene, and polycarbonate diol.

45. The method as defined in claim 21, wherein said second component includes rubber, said rubber including one or more compounds selected from the group consisting of SBS, SEBS, SIS, and nitrile rubber, a weight ratio of said rubber to said polyurethane is 1:0.2 to 1:15.

46. The method as defined in claim 21, wherein said wherein said first component includes a blend of said coal tar and said bitumen, a weight ratio of said coal tar and said bitumen 1:0.1 to 1:10.

47. The method as defined in claim 21, wherein said method further includes the step of adding one or more additives to said first and second component, said additive selected from the group consisting of processing oil, chain extender, modifier, antioxidant, and catalyst, said additive constituting 10-66 wt. % of said bitumen material.

48. The method as defined in claim 21, wherein said polyol includes both diols and triols, a weight ratio of said diols to said triols is about 1:1 to 5:1.

49. The method as defined in claim 21, wherein a weight ratio of said second component to said first component is 0.1:1 to 0.5:1.

50. The method as defined in claim 21, wherein said second component includes at least one chain extender.

51. The method as defined in claim 45, wherein said chain extender includes one or more compounds selected from the group consisting of propylene glycol, ethylene glycol, 1,3-butanediol, and dipropylene glycol.

52. The method as defined in claim 21, wherein said bitumen material comprises by weight percent: TABLE-US-00009 Bitumen and/or coal tar 30-70% Polyurethane 4-20% Filler 10-66%.

53. The method as defined in claim 21, wherein said bitumen material comprises by weight percent: TABLE-US-00010 Bitumen and/or coal tar 50-55% Polyurethane 8-20% Filler 30-41%.

54. The method as defined in claim 21, wherein said bitumen material comprises by weight percent: TABLE-US-00011 Bitumen and/or coal tar 50-55% Polyurethane 8-20% Filler 30-41%. Process oil 1-5%.

55. The method as defined in claim 21, wherein said bitumen material comprises by weight percent: TABLE-US-00012 Bitumen and/or coal tar 50-55% Polyurethane 8-20% Filler 30-41%. Process oil 1-3%.

56. The method as defined in claim 21, wherein said bitumen material comprises by weight percent: TABLE-US-00013 Bitumen and/or coal tar 25-75% Polyurethane 2-49% Filler .sup.1-66%. Process Oil .sup.1-20%. Rubber 1-30% Modifier 0.01-5% Antioxidant 0.01-5% Catalyst 0.01-1%.

57. The method as defined in claim 21, wherein said bitumen material comprises by weight percent: TABLE-US-00014 Bitumen 50-55 Calcium Carbonate 5-40 Aluminum Trihydrate 0.5-20 Ammonium Polyphosphate 0.1-5.sup. Polyurethane .sup.8-20.

58. A method for forming a roof membrane on a roof, said method comprises: a. providing an actively modified polymer-modified bitumen material, said bitumen material comprising 25-75 wt. % of a first component comprising bitumen, coal tar, or combinations thereof; 1-49% wt. % of a second component comprising polyisocyanate compound and polyol; and wherein a content of said polyol in said bitumen material creates a NCO/OH equivalent ratio of at least 2:1; and, b. applying said bitumen material to said roof to form a weather-resistant and waterproof membrane on said roof.

Description

EXAMPLE 1BASED ON FORMULA 1

[0046]

TABLE-US-00003 Component Component Weight Percent PG 64-22 Bitumen 50-55% (or other bitumen) Rubinate 9433 4,4-MDI 8-20% R45HTLO Hydroxy-terminated polybutadiene Krasol LBH 2000 Linear Hydroxy-terminated polybutadiene Poly CD220 2000 MW Polycarbonate diol CaCO.sub.3, Aluminum Filler, Flame retardant 30-41% trihydrate (ATH),

TABLE-US-00004 Component Component Weight Percent Potassium polyphosphate

EXAMPLE 2BASED ON FORMULA 1

[0047]

TABLE-US-00005 Component Component Weight Percent PG 64-22 Bitumen 50-55% (or other bitumen) Hyperlast LP 5610 Linear butadiene/MDI based 8-20% diisocyanate terminated prepolymer R45HTLO Hydroxy-terminated polybutadiene Poly CD220 2000 MW Polycarbonate diol CaCO.sub.3, Aluminum Filler, Flame retardant 30-41% trihydrate (ATH), Potassium polyphosphate

[0048] One non-limiting method for creating the composition of Formula 1 and Example 1 is to add the monomeric, polymeric, or prepolymeric diisocyanate to the molten bitumen or a blend of bitumen and fillers at a process temperature of about 160-179.4 C. (320-355 F.) for about 10-60 minutes (e.g., 25-35 min., etc.). Then, after determination of residual % NCO using potentiometric titration or other method familiar to those skilled in the art, enough polyol is added to react with the remaining isocyanate pendant groups. The blend of polyols will help determine the physical properties of the final product, so choice of blend is important. Another non-limiting method for creating the composition of Formula 1 and Example 1 is to first extend the prepolymeric diisocyanate further using processes familiar to those in the art with additional polyol or polyol blends such that the extended prepolymer increases in molecular weight, but still maintains some NCO functionality, but said NCO functionality is lower than the initial prepolymer's NCO content. Said extended NCO-dominated prepolymer is then added to molten bitumen or a blend of molten bitumen and fillers at 160-179.4 C. (320-355 F.). After allowing the reaction of the NCO-terminated prepolymer and hydroxyl pendant groups of the asphaltine molecules within the bitumen, titration can be used to determine if any residual NCO exists, which in turn can be used to calculate the equivalents of an optional amount of chain extender or other polyol and/or amine structure to increase viscosity, but is not necessary.

Formula 2: Active Modification of SBS-Modified Asphalt

[0049]

TABLE-US-00006 Component Weight Percent Bitumen 50-55% Rubber (SBS, SEBS, SIS, 4-20% Loading and blends thereof) Total at Various Diisocyanate (monomeric, Ratios polymeric, or prepolymeric) Polyol (diol, triol, diol/triol blend) Filler 10-66% Process Oil 1-5%

EXAMPLE 3BASED IN FORMULA 2

[0050]

TABLE-US-00007 Component Component Weight Percent PG 64-22 Bitumen 50-55% SBS, SIS, SEBS (or Rubber In various weight blends thereof) ratios such Polymeric MDI NCO-terminated that the overall polymeric diisocayante weight % is PPG 2000 2000 MW polyol less than or Voranol 220-530 500 MW diol equal to 20% CaCO.sub.3, Filler, flame retardant 30-41% Aluminum trihydrate, Ammonium polyphosphate Naphthenic process oil Process oil 1-3%

[0051] One non-limiting method for creating the composition of Formula 2 and Example 3 is to first blend the SBS, SIS, and/or SEBS or blend thereof into molten asphalt, followed by the fillers. Once the rubber/asphalt blend is fully associated, the polymeric diisocyanate follows, but the prepolymer can be extended ahead of time with a polyol blend, but is not necessary. Reaction temperature should remain between 160-179.4 C. (320-355 F.); higher temperature increases the risk of gelation.

[0052] Table 1 shows physical properties observed in modified bitumen roofing membranes made with the aforementioned formulations compared to a control produced using conventional processes.

TABLE-US-00008 TABLE 1 Physical Properties Observed With Invention vs. Control Component Control Example 1 Example 2 Example 3 Softening Point 272 F. 400 F. 400 F. 290 F. (ASTM D3461, F.) Penetration 20 dmm 21 dmm 31 dmm 22 dmm (ASTM D5, Units) Compound Stability Pass 225 F. Pass 225 F. Pass 225 F. Pass 220 F. (ASTM D5147) Granule Loss 4% 0.7% 0.9% 2% (%, Dry, ASTM D4977) Aged Appearance 4000 Some cracking, No cracking, No cracking, No cracking, hours in Q-Sun Weathering shrinkage, sagging. shrinkage, sagging, shrinkage, sagging, shrinkage, sagging, Some blisters blisters blisters blisters Low Temperature Flexibility Pass 50 F. Pass 10 F. Pass 20 F. Pass 30 F. Granule Loss after 4000 6% 1% 1% DNT h Exposed in Georgia (%, Dry, ASTM D4977) Granule Loss after 4000 7% 1% 1% DNT h Exposed in California (%, Dry, ASTM D4977)

[0053] Table 1 shows that for the membrane made using Example 1, wherein only polyurethane comprised the total polymer content, the softening point increased to 400 F., which translates to improved high temperature sag resistance. In fact, even when exposed to 300 F., the membrane made with Example 1 did not show any signs of sag or mineral loss, while the control softened to the point where flow occurred. However, the membrane retained its flexibility at low temperature. The mineral roofing membrane created with Example 3 had properties closer to that of the Control. This is to be expected as the asphalt will take on properties of both polymers.

[0054] ASTM D412 Stress-Strain Testing of QUV-Aged Films

[0055] To demonstrate the resistance to aging of the invention made by the Examples (specifically Example 1), films of just the modified bitumen were placed into a QUV chamber for 3000+ hours and tested at 500 hour intervals to determine peak stress values. At these intervals, 1 wide strips were cut and pulled on a tensile tester until failure. Graph 1 shows the results.

[0056] The data in Graph 1 shows that prior to 2000 hours there is a steady increase in strength which occurs as a result of UV-induced crosslinking reactions that can occur in both traditional rubber and urethanes. Significantly, beyond 2000 hours there is a 13% decrease in strength in the urethane compared to a nearly 40% decrease in strength with the conventional modified bitumen as the films are continually exposed in the intense UV-rich environment. This trend continues with little change to 3000 hours.

[0057] ASTM 4977 Scrub TestingMineral Loss

[0058] The mineral retention properties of the membrane made by the Examples (specifically Example 1), show significant improvement over the conventionally produced roofing membrane. When the substrates were aged over 4000 hours in California and Georgia, mineral retention in Example 1 was 6-7 times better than the conventional roofing membrane. To further test the invention's mineral retention, specimens of mineral roofing membranes made with Example 1 were soaked for 72 hours in water, and then a granule loss test was performed on the wet aged samples alongside a control similarly conditioned. The results are shown in Graph 2.

[0059] Wet scrub testing was not performed on Example 2. The data in Graph 2 clearly shows that Example 1 has an eight-fold improvement in mineral retention vs. the conventional mineral cap sheet. When tested dry, Examples 1 and 2 still show a three-fold improvement in mineral loss.

[0060] ASTM D4798 Cycle A-1 Weathering

[0061] As a demonstration of the improved weatherability of the invention, environmental aging was performed in a Q-Sun Model XE-3-HS (Q-Lab). Exposures of the non-limiting examples of the invention verses a similarly prepared convention mineral cap sheet show that, after more than 4000 hours subjected to ASTM D4798 Cycle A-1, wherein the prepared panels were subjected to a continuous hourly cycle consisting of a 51-minute light only exposure of noon day sun at 60 C. at equilibrium, followed immediately by a 9-minute period of light/water spray, Examples 1 and 2 show no signs of blistering or surface defects, while the conventional mineral cap sheet had begun to show signs of small blisters on the surface.

[0062] 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.