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
1999-01-15
2001-05-08
Seidleck, James J. (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...
C525S240000, C525S207000, C525S301000, C525S064000, C525S069000, C525S309000
Reexamination Certificate
active
06228948
ABSTRACT:
FIELD OF INVENTION
This invention relates to producing a polymeric composition to function as “adhesion promoters” for a number of applications. For example, the product of this invention can be dispersed in water and applied as an aqueous coating onto glass fiber. Other uses include improve dyeability and paintability of thermoplastic olefins (TPO). The product is also very effective as the fucntionalized source in formulations used for bonding dissimilar material to polypropylene substrates.
BACKGROUND OF THE INVENTION
There are numerous patents on grafting maleic anhydride and other monomers to polyolefins. For example U.S. Pat. No. 4,612,155 of R. A. Zelonka and C. S. Wong teaches the grafting of unsaturated monomers onto the polyolefins in an extruder.
U.S. Pat. No. 3,862,265 and its division No. 4,001,172, both issued to Steinkamp et al, disclose an extrusion reaction of polyolefins to a high level of grafting having melt flow rates (MFR) when measured at 230° C. that are claimed to be up to 1000 dg/min but for polypropylene (PP) only up to 71 dg/min. The percent of maleic anhydride grafted to PP is shown to be only up to 0.53% by weight. These patents show that the use of a special reaction zone within an extruder can be chosen to effect intensive mixing of added reactants to a polymer or distribution of the added reactants to a polymer. The process allows not only the polymer to be modified in terms of its rheology but it may also be simultaneously modified by chemical means.
British Patent No. 679,562 shows graft polymerization of polymers when subjected to suitable mechanical mixing through filters or capillary tubes at high linear velocities.
U.S. Pat. Nos. 3,177,270 and 3,177,269 each discloses the formation of a graft copolymer by adding a monomer and an initiator. The products are “malaxed” to such a low degree that no degradation takes place.
U.S. Pat. No. 3,013,003 shows that degradation in an extruder can be controlled by utilizing a stabilizer.
The patents noted above do not disclose the art of producing a material having a melt flow rate (MFR) above 500 dg/min in an extruder or a material that is pelletizable, or a highly-grafted material. Some of the previous patents state total amounts, not actual grafted amounts of monomer in a polyolefin product.
SUMMARY OF THE INVENTION
The present invention provides in one aspect, a polymer composition comprising a grafted polypropylene polymer having a melt flow rate (MFR) of at least 500 dg/min as measured by ASTM standard E-1238 (190° C., 2160 g) and a grafted monomer content of at least 1 weight percent of functionalized polypropylene.
In another aspect the invention provides a polymer composition comprising a polypropylene polymer with up to 10 weight % ethylene, having grafted to it at least about 1.0 weight percent maleic anhydride measured by FTIR spectroscopy and a melt flow rate of at least about 500 dg/min when measured at 190° C. with a load of 2160 g. The polymer may be a homopolymer or a copolymer of polypropylene.
In yet another aspect the invention provides a method for making a polymer composition comprising a grafted polypropylene polymer having a melt flow rate (MFR) of at least 500 dg/min as measured by ASTM standard E-1238 (190° C., 2160 g) and a grafted monomer content of at least 1 weight percent of functionalized polypropylene, which comprises placing in a twin screw extruder, the propylene polymer, maleic anhydride, and peroxide initiator, mixing them in the extruder, while venting volatiles, and extruding the polymer through a die as strands and chopping the strands into pellets.
REFERENCES:
patent: 3013003 (1961-12-01), Maragliano et al.
patent: 3177269 (1965-04-01), Nowak et al.
patent: 3177270 (1965-04-01), Jones et al.
patent: 3862265 (1975-01-01), Steinkamp et al.
patent: 3987122 (1976-10-01), Bartz et al.
patent: 4001172 (1977-01-01), Steinkamp et al.
patent: 4612155 (1986-09-01), Wong et al.
patent: 5955547 (1999-09-01), Roberts et al.
patent: 679562 (1952-09-01), None
Flaris Vicki
Mitchell David John
Asinovsky Olga
E. I. Du Pont de Nemours and Company
Seidleck James J.
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