Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-12-13
2004-05-11
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S506000, C525S089000, C525S093000, C525S094000, C525S095000
Reexamination Certificate
active
06734247
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a polymer alloy comprising a brittle polymer and either a ductile polymer, a rubbery polymer, or a ductile polymer and a rubbery polymer. More particularly, the invention pertains to a polymer alloy comprising at least a brittle polymer component having a weight average molecular weight greater than 180,000 and a plasticizer in an amount greater than 0.4 weight percent. The polymer alloy gives improved toughness with excellent transparency and/or improved low haze with improved toughness and stiffness.
2. Background Art
It is known in the art that some physical properties of styrenic or acrylic type polymers may be improved by alloying them with one or more additional polymers. In some cases, the resulting mixture can have improved mechanical properties, such as improved impact strength or toughness. However, as impact strength or toughness is improved, the stiffness of the alloy usually is decreased.
Chemical Abstracts 109:171278v [Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) 1988, 29(2), 180-1] discloses that physical blends of block SBR (styrene content: 75.2 weight percent) and a copolymer of methyl methacrylate and styrene are mechanical properties of the blend are partially compatible. The morphological and mechanical properties of the blend are strongly dependent on the molding/mixing process used to produce the blend. The SBR could only be toughened when the ideal morphology of the blend was obtained.
Chemical Abstracts 106:85901z [JP 61/200,151] discloses thermoplastic compositions comprising from 5 to 95 weight percent of a block copolymer and from 95 to 5 weight percent of a thermoplastic polymer (e.g. ABS). The block copolymer is derived from coupling an aromatic vinyl polymer block with an aromatic vinyl monomer-conjugated diene copolymer block. The subject thermoplastic compositions apparently have improved impact strength.
Chemical Abstracts 112:8285y [JP 61/291,610] discloses the use of “impact modifiers” for thermoplastic polymers. The modifiers are basically similar to the block copolymer disclosed by Chemical Abstracts 106:85901z.
Chemical Abstracts 99:196070j [JP 58/122,954] discloses improvement of anisotropy of a styrene hydrocarbon-conjugated diene block copolymer by blending it with a styrene-methacrylic ester copolymer. Such a blend, when extruded to form a molded plate, apparently possesses superior physical properties.
Chemical Abstracts 111:8522c [JP 01/45614] discloses high-impact styrene polymer compositions comprising a major amount of a styrene (50 to 90 weight percent)-conjugated diene (50 to 10 weight percent) block copolymer and a minor amount of a styrene-based polymer (e.g. styrene-methyl methacrylate copolymer).
U.S. Pat. No. 5,290,862, assigned to the same assignee as that of the present invention, discloses a polymer alloy comprising (i) from 30 to 82 weight percent of a brittle polymer; (ii) from 3 to 50 weight percent of a rubbery polymer; and (iii) from 15 to 67 weight percent of a ductile polymer which is compatible with the rubbery polymer. The polymer alloy possesses a combination of improved properties, including improved impact strength. Typically these alloys have a Notched IZOD impact strength of greater than 0.5 foot pound/inch, preferably greater than 1.0 foot pound/inch, and may have a haze of less than 10, most preferably less than 5. The brittle polymer generally may have a molecular weight of about 220,000.
Even though the polymer alloy of the above U.S. Pat. No. 5,290,862 is adequate for certain end use applications, such as patio tumblers, requiring extremely low haze and good impact resistance, some critical applications may require a polymer alloy material with improved low haze with improved toughness and stiffness and/or improved toughness with excellent transparency.
SUMMARY OF THE INVENTION
The invention has met the above need. The invention provides an improved tough and transparent polymer alloy comprising:
from 90 to 20 weight percent of a brittle polymer;
from 0 to 60 weight percent of a rubbery polymer; and
from 0 to 80 weight percent of a ductile polymer whereby the ductile polymer and the rubbery polymer are compatible; and
greater than 0.4 weight percent of a plasticizer.
The brittle polymer has a weight average molecular weight greater than 180,000. In a first embodiment, the weight average molecular weight is greater than 220,000, preferably ranging between 270,000 and 300,000, and most preferably is 280,000. In a second embodiment of the invention, the weight average molecular weight ranges between about 190,000 and 300,000; and preferably ranges between 195,000 and 270,000. Both the first and the second embodiments comprise the brittle polymer and the plasticizer and either the rubbery polymer or the ductile polymer or both.
The polymer alloy of the first embodiment is comprised of from about 80 to 20 weight percent, preferably from about 70 to about 40 weight percent, and most preferably, about 50 to about 55 weight percent of the brittle polymer; from 0 to about 3 weight percent, and more preferably, 0 weight percent of the rubbery polymer; from about 20 to 80 weight percent, preferably from about 30 to 60 weight percent, and most preferably about 50 to about 45 weight percent of the ductile polymer; and from about 0.5 to about 3.0 weight percent, preferably from about 1 to about 2 weight percent, and most preferably about 1.5 weight percent of plasticizer.
The polymer alloy of the second embodiment is comprised of from about 80 to 20 weight percent, preferably from about 70 to 50 weight percent, and most preferably, from about 65 to about 55 weight percent of the brittle polymer; from about 5 to about 60 weight percent, preferably from about 5 to about 20 weight percent, and most preferably from about 8 to about 12 weight percent of the rubbery polymer; from about 0 to about 60 weight percent, more preferably from about 20 to about 40 weight percent; and most preferably from about 25 to about 35 weight percent of the ductile polymer; and greater than 0.4 weight percent, more preferably from about 0.5 to about 3.0 weight percent, and most preferably from about 0.7 to about 1.5 weight percent of the plasticizer.
The brittle polymer preferably is a copolymer of a styrene and methyl methacrylate and preferably, the plasticizer is mineral oil. The plasticizer can be part of any one of the polymers comprising the polymer alloy or it can be blended along with the polymers to form the polymer alloy of the invention. Preferably, the plasticizer is part of the brittle polymer and resides in the brittle polymer prior to the brittle polymer being blended with the other polymer components of the polymer alloy of the invention.
The ductile polymer preferably is a styrene butadiene block copolymer and may be present in the polymer alloy in an amount ranging from about 30 to about 60 weight percent. Preferably, the butadiene is present in this styrene butadiene block copolymer in an amount ranging between 20 to 35 weight percent, preferably from about 24 to about 26 weight percent, and more preferably, about 25 weight percent.
The rubbery polymer preferably is a styrene butadiene block copolymer having 55 to 70 weight percent butadiene.
The polymer alloys of the invention have improved low haze with improved toughness and stiffness and/or improved toughness with excellent transparency. For the first embodiment, when the indices of refraction of the different phases of the polymer alloy formed by the polymers and the plasticizer are matched within a + or −0.005, the haze will be less than 5%; when matched within a + or −0.002 the haze will be less than 3%, and more preferably the haze will be less than 1.5%. For the second embodiment, when the indices of refraction of the different phases of the polymer alloy formed by the polymers and the plasticizer are matched within a + or −0.005, the haze will be less than 10%; when matched within a + or &mi
Cooper Richard Albert
Donn Allen Maxwell
Cain Edward J.
Kikel Suzanne
Nova Chemicals Inc.
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