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
1999-09-08
2001-10-09
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...
C525S232000, C525S240000, C525S241000
Reexamination Certificate
active
06300417
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to the field of polymeric systems and more specifically to a method for improving the impact resistance and scratch resistance of polymeric systems.
BACKGROUND OF THE INVENTION
The increasing market demand for structural applications of polymeric systems has dramatically heightened the importance of impact resistant and scratch resistant polymeric systems. For example, the automotive industry utilizes polymeric systems in the fabrication of automobile bumpers and fenders, which require both high impact resistance and high scratch resistance. Improving the impact resistance of a polymeric system, however, generally reduces the scratch resistance. Moreover, improving the scratch resistance generally reduces impact resistance. Known methods have been unsuccessful in improving both the impact and scratch resistance of polymeric systems.
Known methods of improving the impact resistance and scratch resistance of polymeric systems utilize additives and fillers to improve performance. In one type of method, rubber may be added as a toughener to improve the impact resistance of a polymeric system. The addition of rubber, however, typically reduces scratch resistance. Moreover, the addition of inorganic fillers has failed to increase the scratch resistance. In another type of method, rigid polymers are blended together to improve toughness. Blending randomly chosen rigid polymers, however, usually results in blends with unpredictable properties. Moreover, known rigid-rigid polymer blends do not exhibit satisfactory toughness.
While these approaches have provided improvements over prior approaches, the challenges in the field of polymeric systems have continued to increase with demands for more effective techniques. Therefore, a need has arisen for a new method for improving the impact resistance and scratch resistance of polymeric systems.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method for improving the impact resistance and scratch resistance of polymeric systems is provided that substantially eliminates or reduces the disadvantages and problems associated with previously developed methods.
According to one embodiment of the invention, a method is disclosed. First, a starting material having a Young's modulus is provided. Second, from a plurality of possible modifiers, a modifier is identified and selected that has a Young's modulus comparable to or greater than that of the starting material and that, when blended with the starting material, creates a blend with a stable morphology. Third, the scratch resistance of the starting material is increased by blending the modifier with the starting material to form a blend.
According to another embodiment of the invention, a method for increasing the impact resistance and scratch resistance of a starting material is disclosed. First, a starting material having a Young's modulus is provided. Second, a modifier having a Young's modulus comparable to or greater than that of the starting material is provided. Third, the scratch resistance of the starting material is increased by blending the modifier with the starting material to form a blend, the modifier being operable to create a blend with a stable morphology, to remain in a dispersed phase of the blend, and to trigger crazing or shear banding in the blend. Fourth, a compatibilizer is added to the blend, wherein the compatibilizer is operable to increase the particle dispersion and interfacial adhesion of the blend.
According to yet another embodiment of the invention, a method for increasing the impact resistance and scratch resistance of a starting material is disclosed. First, a starting material comprising polypropylene is provided. Second, a modifier comprising NORYL-PX0844 is provided. Third, the scratch resistance of the starting material is increased by blending the modifier with the starting material to form a blend.
According to another embodiment of the invention, a method for maintaining the scratch resistance of a starting material while increasing the toughness of the starting material is disclosed. First, a starting material having a Young's modulus is provided. Second, a modifier having a Young's modulus comparable to or greater than that of the starting material is provided. Third, the scratch resistance of the starting material is maintained and the toughness of the starting material is increased by blending the modifier with the starting material to form a blend, the modifier being operable to create a blend with a stable morphology, to remain in a dispersed phase of the blend, and to trigger crazing or shear banding in the blend. Fourth, a compatibilizer is added to the blend, wherein the compatibilizer is operable to increase the particle dispersion and interfacial adhesion of the blend.
A technical advantage of the present invention is that the modifier improves both the impact and the scratch resistance of a polymeric system. Alternatively, the modifier maintains the scratch resistance of a polymeric system while increasing the toughness of the polymeric system. Another technical advantage of the present invention is that the compatibilizer improves the miscibility between the modifier and the polymeric system, enhancing the toughness of the system. These technical advantages dramatically increase the quality of polymeric systems as used in many structural applications, for example, the fabrication of automobile bumpers and interior instrument panels.
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.
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Sue H. J.
Wei G-X
Baker & Botts L.L.P.
Nutter Nathan M.
The Texas A&M University System
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