LOW DENSITY THERMOPLASTIC ELASTOMERS
A thermoplastic elastomer (TPE) is disclosed which is foamed and has low density by virtue of the use of glass microspheres.
1 . A low density thermoplastic elastomer compound, comprising:
(a) styrene-containing thermoplastic elastomer and
(b) an efficacious amount of glass microspheres to reduce density of the compound to less than 0.8 g/cm 3 ; and
optionally (c) plasticizer.
2 . The compound of claim 1 , wherein the styrene-containing thermoplastic elastomer is selected from the group consisting of styrene-ethylene-butylene-styrene, styrene-ethylene-propylene-styrene, styrene-ethylene-ethylene/propylene-styrene, styrene-isobutylene-styrene, styrene-butadiene-styrene, styrene-isoprene-styrene, and combinations thereof.
3 . The compound of claim 1 , wherein the styrene-containing thermoplastic elastomer is styrene-ethylene-butylene-styrene.
4 . The compound of claim 3 , wherein the styrene-ethylene-butylene-styrene has a polystyrene content of between about 29 and 32, a specific gravity of about 0.9, and a Shore A hardness of between about 60 and 75.
5 . The compound of claim 1 , wherein the plasticizer is present and is an oil.
6 . The compound of claim 5 , wherein the plasticizer is a paraffinic oil.
7 . The compound of claim 1 , wherein the glass microspheres have a volume average diameter of between about 5 and about 100 micrometers, wherein the glass microspheres have a collapse strength in excess of anticipated pressures that may arise during mixing of the compound, and have a density of between about 0.1 and about 0.9 g/cm 3 .
8 . The compound of claim 1 , further comprising adhesion promoters; biocides; anti-fogging agents; anti-static agents; bonding, blowing and foaming agents; dispersants; fillers and extenders; fire and flame retardants and smoke suppressants; impact modifiers; initiators; lubricants; micas; pigments, colorants and dyes; plasticizers; additional processing aids; release agents; silanes, titanates and zirconates; slip and anti-blocking agents; stabilizers; stearates; ultraviolet light absorbers; viscosity regulators; waxes; and combinations of them.
9 . The compound of claim 1 , wherein the weight percents of the ingredients comprise:
Styrene-containing thermoplastic elastomer
3-95%
Glass Microspheres
3-25%
Plasticizer
0-97%
Anti-oxidant
0-3%
Processing Stabilizer
0-3%
Other Optional Additives
0-15%
10 . The compound of claim 9 , wherein the weight percents of the ingredients comprise:
Styrene-containing thermoplastic elastomer
5-15%
Glass Microspheres
5-20%
Plasticizer
50-90%
Anti-oxidant
0-2%
Processing Stabilizer
0-2%
Other Optional Additives
0-10%
11 . A thermoplastic article, comprising the compound of claim 1 .
12 . The article of claim 11 , wherein the compound includes plasticizer and has a Shore 00 Hardness of from about 10 to about 60.
13 . The article of claim 11 , wherein the article is molded.
14 . The article of claim 11 , wherein the article is extruded.