Purified polymeric materials and methods of purifying polymeric materials
View Patent ↗A method is disclosed to purify a polymeric material by filtering a melt comprising poly(arylene ether) and poly(alkenyl aromatic) through a melt filtration system. The method provides a filtered polymeric composition having reduced levels of particulate impurities. The filtered polymeric composition prepared is suitable for use in data storage media applications.
1. Pellets having an unvibrated bulk density which is greater than or equal to 94% of the vibrated bulk density wherein the pellets consist of a filtered polymeric composition comprising about 90 to about 10 percent by weight of poly(arylene ether) resin and about 10 to about 90 percent by weight of poly(alkenyl aromatic) resin, based on the total weight of the poly(alkenyl aromatic) and poly(arylene ether) resins and
wherein the filtered polymeric composition has, based on an average of five sample measurements, at least one of:
(a) less than 200 particulates having an average diameter of 20 micrometers per gram of the filtered polymeric material,
(b) less than 30 particulates having an average diameter of 30 micrometers per gram of the filtered polymeric material,
(c) less than 5 particulates having an average diameter of 50 micrometers per gram of the filtered polymeric material,
(d) less than 50 particulates having an average diameter within the range of 20 to 100 micrometers per fifteen grams of the filtered polymeric material, and
(e) zero particulates having an average diameter of at least 175 micrometers per gram of the filtered polymeric material.
2. The pellets of claim 1 ,
wherein the poly(arylene ether) comprises at least one of (a) poly(2,6-dimethyl-1,4-phenylene ether) and (b) poly(2,6-dimethylphenylene ether-co-2,3,6-trimethylphenylene ether), and
wherein the poly(arylene ether) has an intrinsic viscosity of about 0.10 to about 0.60 deciliters per gram as measured in chloroform at 25° C.; and
wherein the poly(alkenyl aromatic) is at least one of
(i) atactic homopolystyrene and
(ii) non-elastomeric block copolymer of styrene and one or more polyolefins.
3. The pellets of claim 1 wherein the pellet has a diameter of 3 to 4 millimeters.
4. The pellets of claim 1 wherein the ratio of shortest diameter to longest diameter is 1 to 0.8.
5. The pellets of claim 1 wherein the pellet has a weight of 0.0005 grams to 0.10 grams.
6. The pellets of claim 1 , wherein the pellets have an unvibrated bulk density which is greater than or equal to 96% of the vibrated bulk density.
7. The pellets of claim 1 , wherein the pellets have an unvibrated bulk density which is greater than or equal to 98% of the vibrated bulk density.
8. The pellets of claim 1 , wherein the pellets are substantially free of surface voids that extend greater than or equal to one third of the pellet diameter.