Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-12-14
2001-05-15
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S199000, C525S200000, C525S232000, C525S233000
Reexamination Certificate
active
06232403
ABSTRACT:
BACKGROUND INFORMATION
1. Field of the Invention
The invention relates to the production of an elastomer material which is supposed to demonstrate a high level of thermal and chemical resistance, particularly as a seal material for use in oil-lubricated engines.
2. Description of Related Art
In modern engines, more and more oil types with aggressive additive packages (basic additives, particularly amine components) are being used in order to accomplish various tasks. This is particularly true for transmission oil. These additives frequently result in a change in the elastic properties of seal materials, which result in failure of the elastomer material after a short period of use. This also holds true for fluorocaoutchoucs which are available on the market. In order to achieve better oil resistance, various new elastomer materials were developed. For example, fluorocaoutchouc polymers (FCMs) were introduced, which demonstrate improved resistance to bases, among other things. However, these new fluorocaoutchoucs can only be used for special applications, because of their price. Another approach is based on the idea of using FCMs not as a homopolymer, but rather as an elastomer blend. This involves either a blend of acrylate polymer/FCM, or a blend of ethylene acrylate caoutchouc/FCM. However, the results achieved with them were not satisfactory, particularly not with regard to additives that are strong bases, such as amine additives, which are present in the oil.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an elastomer material that demonstrates a high level of thermal and chemical resistance, and which is particularly useful as a seal material for oil-lubricated engines.
This object and other objects of the invention are accomplished, according to the invention, in that an elastomer material is formed from an elastomer blend of a fluorocaoutchouc (FCM) and of at least a second elastomer of the type of a caoutchouc, where the proportion of the fluorocaoutchouc is not allowed to exceed 5 to 30 phr.
DETAILED DESCRIPTION OF THE INVENTION
In experiments, it was surprisingly shown that even the low proportion of fluorocaoutchouc in the elastomer blend is sufficient to transfer the extremely low relaxation of FCM into the elastomer blend, something that is absolutely necessary for seal materials. This synergistic effect has the result that it becomes possible to combine a high level of resistance of the material to bases, particularly amines, with continued good temperature and oil resistance, particularly the low level of relaxation of FCM, by using only very small amounts of FCM in an elastomer compound. This finding is contrary to those of previous studies. Previous deliberations proceeded from the assumption that an elastomer compound based on pure fluorocaoutchouc or a high proportion of fluorocaoutchouc has the highest level of resistance from a thermal and chemical aspect. However, it was shown that proceeding from a proportion of 100% FCM, the oil resistance does not significantly change as the proportion of FCM is reduced, and actually increases sharply at an FCM proportion of about 30%, and then drops again after reaching a peak. This behavior was tested at use temperatures above 150° C.
In addition to the fluorocaoutchouc component, those elastomers which demonstrate a high polarity and can be crosslinked with peroxide are particularly suitable for production of the elastomer blends. The selection of the second or third elastomer which is blended with the fluorocaoutchouc is made in accordance with these criteria, along with sufficient temperature and media resistance.
It was determined in experiments that a copolymer of ethylene vinyl acetate caoutchouc, tetrafluoroethylene propylene caoutchouc, acrylate caoutchouc or a hydrogenated nitrile caoutchouc yields particularly good results as the second and third elastomer.
In the production of an elastomer blend of only two components, the proportion of the second elastomer is between 70 and 95 phr. However, with an increasing proportion of the second elastomer, the elastomer material became less suitable during processing. It was shown that the use of a third elastomer has a particularly advantageous effect on the processing of the FCM blends.
REFERENCES:
patent: 4987826 (1991-01-01), Deppert et al.
patent: 6079715 (2000-06-01), Johnen et al.
Blumler Norbert
Lux Klaus
Osen Ernst
Peterseim Volker
Firma Carl Freudenberg
Kenyon & Kenyon
Nutter Nathan M.
LandOfFree
Elastomer material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Elastomer material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Elastomer material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2559567