The invention relates to novel bitumen compositions and methods of making the same. It has surprisingly been found that the addition of polyolefin to bitumen feedstock has an effect that is similar to the effect of oxidizing the bitumen feedstock by blowing an oxygen-containing gas through it. This effect can be achieved, in principle, even without the addition of other additives (e.g., styrene/butadiene/styrene triblock copolymer (SBS)). This means that a bitumen’s penetration (also referred to as hardness), softening point and viscosity can be optimized and adjusted to industry standards by adding polyolefin to it. Thus, the present invention allows the optimization of bitumen 115/15 without the shortcomings of oxidizing the bitumen by blowing, which is what is typically done in the art.
The invention provides a non-blown roofing grade bitumen composition comprising: a) bitumen feedstock; b) polyolefin having a molecular weight of from about 800 to about 50,000 g/mol; and c) optionally one or more additives, wherein the softening point of the composition is above 70° C. as determined according to method ASTM D36 and the penetration of the composition is at least about 12 dmm at 25° C. as determined according to method ASTM D5.
Bitumen, also known as asphalt, is the sticky, black and highly viscous liquid or semi-solid present in most crude petroleums and in some other natural deposits. The terms asphalt and bitumen are often used interchangeably to mean both natural and manufactured forms of the substance, both of which are within the scope of the present invention. The production of industry-grade bitumen is generally known in the art and therefore not described herein in any detail.
In the present invention, the bitumen feedstock may be made from any suitable type of bitumen. This includes paving-grade bitumens or a mixture of different paving-grade bitumens. Paving-grade bitumens are typically harder (i.e., have lower penetration) and have a higher softening point and viscosity than those bitumens typically used as feedstock for the oxygen blowing process (e.g., roofing flux feedstock). Paving grade bitumens may be mixed with hard bitumens, pitch, low PEN bitumen and roofing fluxes.
Non-exclusive examples of paving-grade bitumens within the scope of the present invention include paving-grade bitumens having any one of the following performance grades: PG 46-34, PG 52-34, PG 52-28, PG 64-22, PG 64-16, PG 64-10, PG 67-22, PG 70-28, PG 70-22, PG 70-16, PG 70-10, PG 76-28, PG 76-22, PG 76-16 and PG 76-10. Additionally, non-exclusive examples of paving-grade bitumens within the scope of the present invention include paving-grade bitumens having any one of the following penetration grades: 50/70, 60/90, 80/100, 80/120, and 120/150.
In the present invention, the bitumen feedstock may also be made from any suitable type of roofing-grade bitumen, such as, but not limited to, roofing-grade bitumen having any one of the following hardness grades: 100/150 dmm pen, 150/200 dmm pen, 200/300 dmm pen, and 300+ dmm pen.
All of the bitumens disclosed herein, as well as their manufacture, commercial availability and use, are generally known in the art and thus not described herein in detail.