Abstract A tapered styrene-butadiene copolymer is extruded to form a film and a sheet. The tapered styrene-butadiene copolymer can be admixed with polystyrene and is extruded to form a film and is pressed or stretched. The tapered copolymer can be a copolymer of a molecular weight of 40,000 - 250,000 with a total styrene content of 60 - 90 weight percent and with a total butadiene content of 40 - 10 weight percent. More than 10% of the chain portion has a tapering rate of 0.3 - 4. The tapered styrenebutadiene copolymer consists of (a) more than 5% of the chain portion with a styrene content of 30 - 70 weight percent, (b) more than 35% of the chain portion with a styrene content more than 80 weight percent, and (c) more than 10% of the chain portion with a styrene content less than 50 weight percent. When the tapered copolymer of styrene-butadiene or mixtures thereof is extruded and stretched, the resulting transparent film has a high tear strength and impact strength. No white mar is formed when the film is torn or bent.
A PROCESS FOR PRODUCING A FILM OR SHEET FROM A TAPERED STYRENE-BUTADIENE COPOLYMER OR MIXTURE THEREOF WHICH COMPRISES MELT-EXTRUDING THROUGH A T DIE EXTRUDER WHEREIN THE TEMPERATURE OF THE CYLINDER OF THE EXTRUDER IS 140 TO 200* AND THE TEMPERATURE OF THE DIE IS FROM 170* TO 220* AND STRETCCHING AT A STRETCH ROLLER PRESSURE OF 0.25 TO 25 KG/CM2 A TAPERED STYRENE-BUTADIENE COPOLYMER WITH A MOLECULAR WEIGHT OF 40,000 - 250,000, A TOTAL STYRENE CONTENT OF 60 - 90 WEIGHT PERCENT, AND A TOTAL BUTADIENE CONTENT OF 40 - 10 WEIGHT PERCENT, WHEREIN SAID TAPERED STYRENE-BUTADIENE COPOLYMER CONTAINS: (A) MORE THAN 5% OF THE CHAIN PORTION HAVING A TAPERING RATE OF 0.3 - 4 AND A STYRENE CONTENT OF 30 - 70 WEIGHT PERCENT, (B) MORE THAN 35% OF THE CHAIN PORTION WITH A STYRENE CONTENE OF MORE THAN 80% BY WEIGHT, AND (C) MORE THAN 10% OF THE CHAIN PORTION WITH A STYRENE CONTENT FROM AT LEAST 5 WEIGHT PERCENT TO LESS THAN 50 WEIGHT PERCENT BETWEEN HIGH STYRENE CONTENT CHAIN PORTIONS WHICH HAVE A STYRENE CONTENT OF GREATER THAN 80 WEIGHT PERCENT.
Claim 2
Dependent Claim
185 words
A PROCESS FOR PRODUCING A FILM OR SHEET FROM A TAPERED STYRENE-BUTADIENE COPOLYMER OR MIXTURE THEREOF WHICH COMPRISES MELT-EXTRUDING THROUGH A T DIE EXTRUDER WHEREIN THE TEMPERATURE OF THE CYLINDER OF THE EXTRUDER IS 140 TO 200* AND THE TEMPERATURE OF THE DIE IS FROM 170* TO 220* AND STRETCCHING AT A STRETCH ROLLER PRESSURE OF 0.25 TO 25 KG/CM2 A TAPERED STYRENE-BUTADIENE COPOLYMER WITH A MOLECULAR WEIGHT OF 40,000 - 250,000, A TOTAL STYRENE CONTENT OF 60 - 90 WEIGHT PERCENT, AND A TOTAL BUTADIENE CONTENT OF 40 - 10 WEIGHT PERCENT, WHEREIN SAID TAPERED STYRENE-BUTADIENE COPOLYMER CONTAINS: (A) MORE THAN 5% OF THE CHAIN PORTION HAVING A TAPERING RATE OF 0.3 - 4 AND A STYRENE CONTENT OF 30 - 70 WEIGHT PERCENT, (B) MORE THAN 35% OF THE CHAIN PORTION WITH A STYRENE CONTENE OF MORE THAN 80% BY WEIGHT, AND (C) MORE THAN 10% OF THE CHAIN PORTION WITH A STYRENE CONTENT FROM AT LEAST 5 WEIGHT PERCENT TO LESS THAN 50 WEIGHT PERCENT BETWEEN HIGH STYRENE CONTENT CHAIN PORTIONS WHICH HAVE A STYRENE CONTENT OF GREATER THAN 80 WEIGHT PERCENT.
Claim 3
Dependent Claim
26 words
The process of claim 1, wherein said melt-extruding and stretching is conducted by the T-die method whereby a bi-axial orientation is imparted to the tapered copolymer.
Claim 4
Dependent Claim
29 words
The process of claim 1, wherein said tapered styrene-butadiene copolymer is admixed with polystyrene together with an anti-oxidant and the mixture is melt-extruded and stretched by a T-die method.
Claim 5
Dependent Claim
32 words
The process of claim 1, wherein said tapered styrene-butadiene copolymer or a mixture of the tapered copolymer and polystyrene is melt-extruded and stretched to form a film less than 2 mm thick.