Injection-moldable transparent thermoplastic elastomer
First Claim
1. A thermoplastic, injection-moldable and recyclable composition consisting essentially of at least one triblock copolymer selected from the group consisting of(a) a substantially colorless hydrogenated first styrene-conjugated diene-styrene block copolymer (HSBC) derived by hydrogenation of a triblock copolymer selected from the group consisting of high vinyl (styrene-butadiene-styrene) (SBS), high vinyl (styrene-isoprene-styrene) (SIS) and high vinyl (styrene-isoprene/butadiene-styrene) (SI/BS) to yield polystyrene-b-poly(ethylene/butylene)-b-polystyrene (high vinyl SEBS), polystyrene-b-poly(ethylene/propylene-3-methylbutene)-b-polystyrene (SEPS), and “
- polystyrene-b-poly(ethylene-ethylene/propylene)-b-polystyrene (SEEPS), respectively, each triblock having at least 51 mole percent of the butadiene midblock polymerized at the 1,2-position, and/or at least 51 mole percent of the isoprene polymerized at the 3,4-position, wherein (a) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; and
(b) a blend of (a) with a second substantially colorless SEEPS present in a minor proportion relative to the first HSBC (a), wherein the second SEEPS is optionally high vinyl and (b) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000;
a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a polyolefinic modifier providing a continuous phase in the TPE, the polyolefinic modifier being selected from the group consisting of polypropylene homopolymer, and a copolymer of propylene with another lower olefin having from 2 to 6 carbon atoms, the modifier having a melt viscosity in the range from 1 to 150 gm/10 min as measured at 230°
C. under a load of 2.16 kg in accordance with ASTM D1238;
a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a substantially colorless plasticizer or softening agent compatible with rubbery phases of the foregoing;
a minor proportion by weight relative to either (a), or (a) and (b), of an end block modifier which associates with the polystyrene, the end block modifier having a glass transition temperature Tg higher than 60°
C., a MMAP cloud point<
30°
C. and a weight average molecular weight Mw in the range from 2,000 to 50,000; and
,at least one additive to enhance useful life of the composition.
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Accused Products
Abstract
A plasticized HSBC blended with polypropylene and free of a filler material which adversely affects clarity, provides an injection-moldable composition for an article required to have specific properties, namely, tensile strength in the range from about 4.13 to 8.96 MPa (600 to 1300 psi); tear strength in the range from about 21 to 52.6 N/mm (120 to 300 lbs/in); softness in the range from about 45 but less than 65 Shore A; and haze less than 20%, measured by ASTM D1003 using a BYK Gardner Micro Tri-gloss 4525 meter; and it is essential that all of these properties, along with the physical dimensions of the molded article, remain substantially unchanged after immersion of the article in boiling water for 1 hour. Such a composition is may be injection molded to form a nipple for feeding an infant, or a teething ring, or goggles for a diver, and the articles are sterilizable and recyclable.
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Citations
14 Claims
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1. A thermoplastic, injection-moldable and recyclable composition consisting essentially of at least one triblock copolymer selected from the group consisting of
(a) a substantially colorless hydrogenated first styrene-conjugated diene-styrene block copolymer (HSBC) derived by hydrogenation of a triblock copolymer selected from the group consisting of high vinyl (styrene-butadiene-styrene) (SBS), high vinyl (styrene-isoprene-styrene) (SIS) and high vinyl (styrene-isoprene/butadiene-styrene) (SI/BS) to yield polystyrene-b-poly(ethylene/butylene)-b-polystyrene (high vinyl SEBS), polystyrene-b-poly(ethylene/propylene-3-methylbutene)-b-polystyrene (SEPS), and “ - polystyrene-b-poly(ethylene-ethylene/propylene)-b-polystyrene (SEEPS), respectively, each triblock having at least 51 mole percent of the butadiene midblock polymerized at the 1,2-position, and/or at least 51 mole percent of the isoprene polymerized at the 3,4-position, wherein (a) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; and
(b) a blend of (a) with a second substantially colorless SEEPS present in a minor proportion relative to the first HSBC (a), wherein the second SEEPS is optionally high vinyl and (b) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a polyolefinic modifier providing a continuous phase in the TPE, the polyolefinic modifier being selected from the group consisting of polypropylene homopolymer, and a copolymer of propylene with another lower olefin having from 2 to 6 carbon atoms, the modifier having a melt viscosity in the range from 1 to 150 gm/10 min as measured at 230°
C. under a load of 2.16 kg in accordance with ASTM D1238;a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a substantially colorless plasticizer or softening agent compatible with rubbery phases of the foregoing; a minor proportion by weight relative to either (a), or (a) and (b), of an end block modifier which associates with the polystyrene, the end block modifier having a glass transition temperature Tg higher than 60°
C., a MMAP cloud point<
30°
C. and a weight average molecular weight Mw in the range from 2,000 to 50,000; and
,at least one additive to enhance useful life of the composition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- polystyrene-b-poly(ethylene-ethylene/propylene)-b-polystyrene (SEEPS), respectively, each triblock having at least 51 mole percent of the butadiene midblock polymerized at the 1,2-position, and/or at least 51 mole percent of the isoprene polymerized at the 3,4-position, wherein (a) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; and
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9. A recyclable, thermoformed, substantially clear and soft, shaped article comprising,
a thermoformed blend consisting essentially of at least one triblock copolymer selected from the group consisting of (a) a substantially colorless hydrogenated first styrene-conjugated diene-styrene block copolymer (HSBC) derived by hydrogenation of a triblock copolymer selected from the group consisting of high vinyl (styrene-butadiene-styrene) (SBS), high vinyl (styrene-isoprene-styrene) (SIS) and high vinyl (styrene-isoprene/butadiene-styrene) (SI/BS) to yield polystyrene-b-poly(ethylene/butylene)-b-polystyrene (high vinyl SEBS), polystyrene-b-poly(ethylene/propylene-3-methylbutene)-b-polystyrene (SEPS), and “ - polystyrene-b-poly(ethylene-ethylene/propylene)-b-polystyrene (SEEPS), respectively, each triblock having at least 51 mole percent of the butadiene midblock polymerized at the 1,2-position, and/or at least 51 mole percent of the isoprene polymerized at the 3,4-position, wherein (a) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; and
(b) a blend of (a) with a second substantially colorless SEEPS present in a minor proportion relative to the first HSBC (a), wherein the second SEEPS is optionally high vinyl and (b) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a polyolefinic modifier providing a continuous phase in the TPE, the polyolefinic modifier being selected from the group consisting of polypropylene homopolymer, and a copolymer of propylene with another lower olefin having from 2 to 6 carbon atoms, the modifier having a melt viscosity in the range from 1 to 150 gm/10 min as measured at 230°
C. under a load of 2.16 kg in accordance with ASTM D1238;a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a substantially colorless plasticizer or softening agent compatible with rubbery phases of the foregoing; a minor proportion by weight relative to either (a), or (a) and (b), of an end block modifier which associates with the polystyrene, the end block modifier having a glass transition temperature Tg higher than 60°
C., a MMAP cloud point<
30°
C. and a weight average molecular weight Mw in the range from 2,000 to 50,000; and
,at least one additive to enhance the useful life of the shaped article. - View Dependent Claims (10, 11, 12, 13)
- polystyrene-b-poly(ethylene-ethylene/propylene)-b-polystyrene (SEEPS), respectively, each triblock having at least 51 mole percent of the butadiene midblock polymerized at the 1,2-position, and/or at least 51 mole percent of the isoprene polymerized at the 3,4-position, wherein (a) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; and
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14. A method for preparing a thermoplastic article, comprising,
blending together at least one triblock copolymer selected from the group consisting of (a) a substantially colorless hydrogenated first styrene-conjugated diene-styrene block copolymer (HSBC) derived by hydrogenation of a triblock copolymer selected from the group consisting of high vinyl (styrene-butadiene-styrene) (SBS), high vinyl (styrene-isoprene-styrene) (SIS) and high vinyl (styrene-isoprene/butadiene-styrene) (SI/BS) to yield polystyrene-b-poly(ethylene/butylene)-b-polystyrene (high vinyl SEBS), polystyrene-b-poly(ethylene/propylene-3-methylbutene)-b-polystyrene (SEPS), and “ - polystyrene-b-poly(ethylene-ethylene/propylene)-b-polystyrene (SEEPS), respectively, each triblock having at least 51 mole percent of the butadiene midblock polymerized at the 1,2-position, and/or at least 51 mole percent of the isoprene polymerized at the 3,4-position, wherein (a) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; and
(b) a blend of (a) with a second substantially colorless SEEPS present in a minor proportion relative to the first HSBC (a), wherein the second SEEPS is optionally high vinyl and (b) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a polyolefinic modifier providing a continuous phase in the TPE, the polyolefinic modifier being selected from the group consisting of polypropylene homopolymer, and a copolymer of propylene with another lower olefin having from 2 to 6 carbon atoms, the modifier having a melt viscosity in the range from 1 to 150 gm/10 min as measured at 230°
C. under a load of 2.16 kg in accordance with ASTM D1238;a minor proportion by weight, relative to the amount of (a) or the combined amount of (a) and (b), of a substantially colorless plasticizer or softening agent compatible with rubbery phases of the foregoing; a minor proportion by weight relative to either (a), or (a) and (b), of an end block modifier which associates with the polystyrene, the end block modifier having a glass transition temperature Tg higher than 60°
C., a MMAP cloud point<
30°
C. and a weight average molecular weight Mw in the range from 2,000 to 50,000; and
,at least one additive to enhance useful life of the article; and
,thermoforming the blend at a temperature above the melt flow temperature of the blend.
- polystyrene-b-poly(ethylene-ethylene/propylene)-b-polystyrene (SEEPS), respectively, each triblock having at least 51 mole percent of the butadiene midblock polymerized at the 1,2-position, and/or at least 51 mole percent of the isoprene polymerized at the 3,4-position, wherein (a) has a resultant effective number average molecular weight (Mn) measured by gas permeation chromatography (GPC), lower than 130,000; and
Specification