Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1998-03-02
1999-09-07
Teskin, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524130, 524577, 526347, 5263472, C08K 55333
Patent
active
059488409
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a composition of matter comprising a highly syndiotactic vinyl aromatic polymer and a crystallization modifier. The invention further relates to a method of controlling the crystallization temperature of a highly syndiotactic vinyl aromatic polymer by intimately blending therein a crystallization modifier. Finally, the present invention relates to an article of manufacture, especially a film, formed from the above polymer composition.
Highly syndiotactic homopolymers and interpolymers of vinylaromatic monomers are well known in the art. Such polymers possess an extremely high crystalline melt temperature, Tm. For example highly syndiotactic polystyrene possesses a Tm of approximately 270.degree. C. Thus, such polymers are highly suited for the manufacture of articles that are exposed to high heat environments. Also, due to the crystalline nature of such polymers, they are well suited for manufacture of articles requiring improved solvent resistance. In fact, at the present time there are no known room temperature solvents for syndiotactic vinylaromatic polymers, especially syndiotactic polystyrene. This fact makes such polymers highly useful in applications requiring both solvent resistance and high temperature resistance. Examples include automotive parts that are exposed to solvents or fuels, and films for protective wrapping especially for use in corrosive environments. Disadvantageously, syndiotactic vinylaromatic polymers crystallize extremely rapidly from the melt and form relatively large crystals that render the polymer opaque or partially opaque. This is because the temperature of crystallization of such polymers is also rather high. Consequently, only slight cooling initiates rapid crystallization and disadvantageously limits the type and quantity of operations that may be performed on the polymer prior to onset of crystallization. For example, drawing and tentering operations for films of conventional syndiotactic vinylaromatic polymers must be performed at elevated temperatures in order to avoid onset of crystallization or else they must be performed too rapidly to be convenient for commercial operations. Moreover, the presence of large crystallites of such polymers limits the applications of resulting products to those articles where transparency is not required.
One attempt to modify the crystallization kinetics of vinylaromatic polymers has involved the use of interpolymers. For example, highly syndiotactic copolymers of styrene and a ring alkyl-substituted styrene, particularly p-vinyltoluene, have a significantly lower crystallization temperature (Tc) than syndiotactic polystyrene itself. Disadvantageously, such copolymers also possess a lower crystalline melt temperature, Tm, thereby limiting the ultimate use temperature of articles made from such interpolymers. Moreover, copolymerizations are inherently more complex and expensive processes that require separate monomer purification and handling equipment as well as more complex recycle and recovery procedures. These result in added costs for such interpolymers. Also, the crystal size of such interpolymers still is too large for highly transparent articles. Thus the use of copolymers to control the crystallization temperature of these polymers is not entirely successful. Finally, it would also be desirable to be able to adjust the crystallization properties of copolymer products independently of the quantity of comonomer therein in order to provide more flexibility to even copolymer products.
Accordingly, there remains a need to produce highly syndiotactic vinylaromatic polymers having altered crystallization kinetics, particularly a reduced crystallization temperature, in a cost effective manner, without detrimental reduction in the crystalline melting point, Tm, thereof.
The present invention provides a polymer composition comprising: crystallization modifier selected from the group consisting of alkaline earth metal bis(monoethyl(3,5-di-t-butyl-4-hydroxybenzyl)phosphonate) salts.
The present invention also pro
REFERENCES:
patent: 5034441 (1991-07-01), Nakano et al.
patent: 5326813 (1994-07-01), Okada et al.
patent: 5362783 (1994-11-01), Eiffler et al.
Fay Joseph J.
Maecker Norbert L.
Teskin Fred
The Dow Chemical Company
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