Thermoplastic elastomer and process for producing it
AssigneeMitsui Chemicals, Inc.
InventorsYuichi Itoh, Akira Uchiyama
Life of this patent
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Abstract
A thermoplastic elastomer exhibiting scarce tendency of depositing gummy crust around the extrusion die upon extrusion molding articles therefrom and a superior oil-resistance, which comprises (A) a crystalline polyolefin resin and (B) a cross-linked rubber component produced by a specific melt-kneading technique and which has a certain high level of gel content, a high oil-resistance and a certain reduced rate of deposition of gummy crust on the extrusion die.
Claims12
A thermoplastic elastomer comprising (A) a crystalline polyolefin resin and (B) a cross-linked rubber component, which has
- a) a gel content expressed as a cyclohexane-insoluble matter after having been soaked in cyclohexane at 23° C. for 48 hours of at least 20% by weight,
- b) a weight change range ΔW after having been soaked in paraffin oil at 50° C. for 24 hours amounting to 80% by weight or lower and
- c) a rate of gummy crust deposition of 30 mg or less within an interval of 10 minutes occuring around the extrusion die upon extrusion of the elastomer into a ribbon on a monoaxial extruder provided with a full-flight extrusion screw having a diameter of 50 mm, an L/D ratio of 28 and a compression ratio of 4.0 through an extrusion die having an extrusion aperture of 25 mm×1 mm under a gradient temperature elevation from the extruder supply inlet to the die outlet of 160-210° C. at an extrusion rate of 20 m/min.
A process for producing a thermoplastic elastomer comprising (A) a crystalline polyolefin resin and (B) a cross-linked rubber component, comprising the steps of
- melt-kneading a crystalline polyolefin resin (A1) together with a rubber component (B1) in the presence of a cross linking agent (D) in a first extruder,
- supplying the resulting kneaded mass in which the cross linking reaction has substantially been completed to a second extruder and
- melt-kneading the so-supplied kneaded mass therein together with a crystalline polyolefin resin (A2) and/or a rubber component (B2) each supplied to the second extruder.
A process for producing a thermoplastic elastomer comprising (A) a crystalline polyolefin resin and (B) a cross-linked rubber component, comprising the steps of
- melt-kneading a crystalline polyolefin resin (A1) together with a rubber component (B1) in the presence of a cross linking agent (D) in a first extruder,
- supplying a kneaded mass of a crystalline polyolefin resin (A2) and/or a rubber component (B2) extruded from a second extruder to the first extruder at a position within the range of the exit-side half of the first extruder and
- melt-kneading the so-supplied kneaded mass (A2 and/or B2) therein together with the kneaded mass which has been subjected to the melt-kneading in the first extruder and in which the cross linking reaction has substantially been completed.
Dependencies are inferred from the claim text.