Tetrablock copolymer and compositions containing same
View Patent ↗Disclosed is a novel tetrablock copolymer having the general configuration of A1-B1-A2-B2, where the A1 and A2 blocks are mono alkenyl arene and the B1 and B2 blocks are blocks of hydrogenated butadiene, having a 1,2-vinyl content of between 25% and 60%. The blocks have well defined molecular weight ranges, resulting in a polymer having a unique set of property advantages. Also disclosed are elastomeric compositions containing the linear hydrogenated block copolymer, a styrene polymer, an ethylene polymer and a tackifying resin. These elastomeric compositions have particular utility in injection molded parts and in extruded parts such as extruded films and fibers.
1. An elastomeric composition comprising:
a. about 50 to about 80 weight percent of a linear hydrogenated block copolymer consisting of four alternating blocks having the block arrangement of A 1 -B 1 -A 2 -B 2 wherein:
(i) each polymer block B 1 and B 2 comprises polymerized, hydrogenated butadiene monomer units in which at least 90% of the olefinically unsaturated double bonds contained in the unhydrogenated polymer block are hydrogenated, and in which the unhydrogenated polymer block have a 1,2-vinyl bond content of greater than 25% and less than 60%;
(ii) each polymer block A 1 and A 2 comprises polymerized mono alkenyl arene monomer units;
(iii) the number average molecular weights of the blocks are between 6,000 and 8,000 for the A 1 block, between 55,000 and 70,000 for the B 1 block, between 7,500 and 9,000 for the A 2 block and between 5,000 and 12,000 for the B 2 block; and
(iv) wherein said linear hydrogenated block copolymer has an order-disorder temperature of less than 240° C., a melt flow rate of less than 2.0 g/10 minutes as measured at 200° C. under a load of 5kg in accordance with ASTM D1238 and a melt flow rate of between 4.0 and 20.0 g/10 minutes as measured at 250° C. under a load of 5kg in accordance with ASTM 1238D;
b. about 4 to about 15 weight percent of a styrene polymer selected from the group consisting of crystal polystyrene and anionically polymerized polystyrene;
c. about 5 to about 20 weight percent of an olefin polymer selected from the group consisting of ethylene polymers and copolymers, propylene polymers and copolymers, and butylene polymers and copolymers; and
d. about 0 to about 25 weight percent of a tackifying resin.
2. The elastomeric composition of claim 1 wherein said mono alkenyl arene is styrene, and wherein the number avenge molecular weights of the blocks are between 6,550 and 7,250 for the A 1 block, between 55,000 and 65,000 for the B 1 block, between 8,000 and 9,000 for the A 2 block, and between 5,000 and 8,000 for the B 2 block.
3. The elastomeric composition of claim 2 wherein the melt flow rate at 250° C. under 5 kg load of said linear hydrogenated block copolymer is between 5 and 15 g/10 minutes and wherein said order-disorder temperature is between 210 and 240° C.
4. The elastomeric composition of claim 3 wherein the amount of linear hydrogenated block copolymer is between about 60 and 80 weight percent, the amount of styrene polymer is between about 5 and 10 weight percent, the amount of olefin polymer is between about 5 and 15 weight percent, and the amount of tackifying resin is between about 10 and 25 weight percent.
5. The elastomeric composition of claim 1 wherein said styrene polymer is selected from the group consisting of anionic polystyrene having a number average molecular weight of about 5,000 to about 100,000 and crystal polystyrene having a melt flow above 8 gm/10 min at 200° C. under 5 kg load.
6. The elastomeric composition of claim 5 wherein said styrene polymer is crystal polystyrene having a melt flow of about 15 gm/10 min at 200° C. under 5 kg load.
7. The elastomeric composition of claim 1 wherein said olefin polymer is selected from the group consisting of ethylene polymers and ethylene copolymers.
8. The elastomeric composition of claim 7 wherein said ethylene polymer is selected from the group consisting of low density polyethylene and linear low density polyethylene having a density less than 0.93 grams per cubic centimeter.
9. The elastomeric composition of claim 1 wherein said tackifying resin is a hydrogenated hydrocarbon resin.
10. The elastomeric composition of claim 9 wherein said tackifying resin is a hydrogenated α-methyl styrene resin.
11. The elastomeric composition of claim 1 also containing one or more additives selected from the group consisting of uv stabilizers, antioxidants, optical brighteners and pigments.
12. A film extruded from the elastomeric composition of claim 1 .
13. A fiber extruded from the elastomeric composition of claim 1 .
14. The elastomeric composition of claim 1 where the polyolefin is a polypropylene polymer or copolymer.
15. An injection molded article prepared from the elastomeric composition of claim 1 .
16. A linear hydrogenated block copolymer consisting of four alternating blocks having the block arrangement of A 1 -B 1 -A 2 -B 2 wherein:
a. each polymer block B 1 and B 2 comprises polymerized, hydrogenated butadiene monomer units in which at least 90% of the olefinically unsaturated double bonds contained in the unhydrogenated polymer block are hydrogenated, and in which the unhydrogenated polymer block have a 1,2-vinyl bond content of greater than 25% and less than 60%;
b. each polymer block A 1 and A 2 comprises polymerized styrene monomer units;
c. the number average molecular weights of the blocks are between 6,550 and 7,250 for the A 1 block, between 55,000 and 65,000 for the B 1 block, between 8,000 and 9,000 for the A 2 block and between 5,000 and 8,000 for the B 2 block; and
d. wherein said linear hydrogenated block copolymer has an order-disorder temperature of less than 240° C., a melt flow rate of less than 2.0 g/10 minutes as measured at 200° C. under a load of 5 kg in accordance with ASTM D1238 and a melt flow rate of between 4.0 and 20.0 g/10 minutes as measured at 250° C. under a load of 5 kg in accordance with ASTM 1238D.
17. The linear hydrogenated block copolymer of claim 16 wherein the melt flow rate at 250° C. under 5 kg load is between 5 and 15 g/10 minutes.
18. The linear hydrogenated block copolymer of claim 17 wherein said order-disorder temperature is between 210 and 240° C.
19. The linear hydrogenated block copolymer of claim 17 wherein the 1,2-vinyl bond content of the unhydrogenated butadiene blocks is between 30% and 55%.
20. An elastomeric composition comprising:
a. 50 to 80 weight percent of the linear hydrogenated block copolymer as claimed in claim 16 ;
b. 4 to 15 weight percent of a styrene polymer selected from crystal polystyrene and anionically polymerized polystyrene;
c. 5 to 20 weight percent of an olefin polymer selected from ethylene polymers and copolymers, propylene polymers and copolymers, and butylene polymers and copolymers; and
d. 0 to 25 weight percent of a tackifying resin.
21. A film or fiber or an injection molded article prepared from the elastomeric composition of claim 20 .