C9 resins contain many double bonds which are relatively unstable. An effective way to stabilize these resins is to hydrogenate them. C9 resins have aromatic ring structures with an overall aromaticity around 40%, measured by proton NMR. Resins are hydrogenated in solution with very specific operating parameters: temperature, pressure, hydrogen concentration, and catalyst level. Changing any one of these operating parameters will bring a change in the degree of hydrogenation of the final resin. During hydrogenation, the aromatic ring structures gradually lose their aromatic nature and become cyclo-aliphatic as seen in Figure 1.
The first hydrogenated C9 hydrocarbon resins were fully saturated producing aliphatic resins with excellent initial color and stability. These resins are ideal for tackifying SIS and SEBS block copolymers. To produce light colored and stable resins with the correct compatibility to tackify SBS block copolymers and to adjust properties in high styrene SIS block copolymers, partially hydrogenated C9 aromatic resins were introduced. This produces a resin with solubility parameters (cloud points) in the same range of C5/C9 mixed aliphatic/aromatic resins but with significantly improved stability and much lower color.
Figure 1: Varying the Degree of Hydrogenation
When the process is allowed to go to completion, the result is a fully hydrogenated hydrocarbon resin with full aliphatic character. The process can also be adjusted so that partially hydrogenated resins are the end result. Partial hydrogenation results in resins for wide use in adhesive formulations and is achieved through sequential, but not total hydrogenation of the rings. This means that partially hydrogenated resins still have some aromatic rings. The ability to be hydrogenated to varying degrees, resulting in various aliphatic/aromatic balances, gives these resins their unique properties. In theory, any degree of hydrogenation can be manufactured. Eastman resins carry a range of hydrogenation levels, varying from 50% to 100%.
Eastman supplies two main brands of hydrogenated C9 hydrocarbon tackifiers, the Regalite brand of selectively hydrogenated resins and the Regalrez brand of fully hydrogenated pure monomer C9 resins. Regalite hydrogenated hydrocarbon resins are available in a variety of softening points, levels of hydrogenation, and additive packages. The grade nomenclature of the Regalite series is a letter (C, R or S) and a four digit code that conveys important information about the product properties. There are three sub-series of the Regalite product line. The Regalite R series is stabilized with an antioxidant package and the Regalite S-series carries no antioxidant. Regalite C series resins are produced in China. The first digit of the code gives the approximate level of hydrogenation: 5 for 50%, 7 for 70%, 9 for 90% and 1 for 100%. The last three digits of the code give the ring and ball softening point of the resin in degrees centigrade.
Table 1: Property Ranges of Regalite C9, Aromatic Hydrocarbon Resins
| Properties |
Range |
| Ring and ball softening point, °C |
10–125 |
| Gardner color (50% in toluene) |
<1 |
| Glass transition temperature, °C |
<0–60 |
| MMAP cloud point, °C |
59–86 |
| DACP cloud point, °C |
8–56 |
The Regalite hydrogenated hydrocarbon resins produced by Eastman Chemical Company are:
Regalite S-Series (No antioxidant added)
Regalite R-Series (With added antioxidant)
Regalite C-Series (Available in Asia-Pacific region only)
Regalite R and S-series hydrogenated hydrocarbon resins are manufactured at the Eastman Chemical Company plant in Middleburg, The Netherlands. To check on availability of any of these products in other regions, please contact a local Eastman sales representative or distributor or inquire via adhesives@eastman.com.
Regalrez hydrogenated pure monomer resins represent the ultimate in low color and high stability. Since they are made from only purified aromatic monomer feedstocks, they are already low in color before the hydrogenation process. Regalrez products are selectively hydrogenated to between 30% and 100%, producing a range of resins with a broad range of properties and compatibilities. Products with high aromaticity as indicated by low MMAP and DACP cloud points have compatibility typical of C9 aromatic hydrocarbon resins. The highly hydrogenated products characterized by high cloud points are most compatible with aliphatic polymers such as SIS, SEBS, polyethylene, and amorphous polyolefins.
Table 2: Property Ranges of Regalrez C9, Aromatic Hydrocarbon Resins
| Properties |
Range |
| Ring and ball softening point, °C |
19–130 |
| Gardner color (50% in toluene) |
<6 |
| Glass transition temperature, °C |
-22–84 |
| MMAP cloud point, °C |
24–109 |
| DACP cloud point, °C |
-15–79 |
Regalrez hydrogenated pure monomer C9, aromatic hydrocarbon resins produced by Eastman Chemical Company are:
Eastman Chemical Company produces Regalrez products in North America and Europe. They are distributed globally. To check on availability of any of these products, please contact a local Eastman sales representative or distributor or inquire via adhesives@eastman.com.