Blend for masterbatches
View Patent ↗Provided is a blend comprising: a) from 20 to 60 wt % of a thermoplastic elastomer; b) from 8 to 30 wt % of a vinylaromatic polymer; c) from 10 to 30 wt % of one or more processing aid; d) from 0 to 20 wt % of one or more additives.
1. A process for the production of a cork for liquid containers comprising providing a masterbatch which comprises:
(a) from 20 to 60 wt. % of a thermoplastic elastomer re resulting from the copolymerization of a vinylaromatic monomer and a conjugated diene monomer containing from 80 to 20 wt. % of the vinylaromatic polymer and 20 to 80 wt. % of the conjugate diene polymer;
(b) from 8 to 30 wt. % of a vinylaromatic polymer, other than the thermoplastic elastomer of subparagraph (a);
(c) from 10 to 30 wt. % of at least one processing aid which decreases the viscosity of the masterbatch allowing improved processing speed;
(d) optionally up to 20 wt. % of one or more additives selected from the group consisting of lubricity agents, which improve the introduction of the cork in containers and fillers;
(e) a blowing agent; and
(f) molding said masterbatch to form a cork.
2. A process according to claim 1 wherein the thermoplastic elastomer is composed of styrenic and butadienic units.
3. A process according to claim 1 wherein the amount of styrene in the elastomer is between 25 to 80 wt. % and the amount of butadiene in the elastomer is from 75 to 20 wt. %.
4. A process according to claim 1 wherein the vinylaromatic polymer is polystyrene.
5. A process according to claim 1 wherein the polystyrene is a mixture of high impact and general purpose polystyrene in an amount from 8 to 25 wt. %.
6. A process according to claim 1 wherein the processing aid is a mixture of naphthenic and paraffinic oil in an amount of 15 to 27 wt. %.
7. A process according to claim 1 wherein the lubricity agent is calcium stearate.
8. A process according to claim 1 comprising a filler in an amount of less than 10%.
9. A process according to claim 8 wherein the filler is calcium carbonate.
10. A process according to claim 1 wherein the blowing agent is a physical blowing agent.
11. A process according to claim 10 wherein the blowing agent is a polymer bead containing isobutane.
12. In a process for the production of a cork for liquid containers, one step of the process comprising mixing:
(a) from 20 to 60 wt. % of a thermoplastic elastomer resulting from the copolymerization of a vinylaromatic monomer and a conjugated diene monome containing from 80 to 20 wt. % of the vinylaromatic polymer and 20 to 80 wt. % of the conjugated diene polymer,
(b) from 8 to 30 wt. % of a vinylaromatic polymer, other than the thermoplastic elastomer of subparagraph (a);
(c) from 10 to 30 wt. % of at least one processing aid which decreases the viscosity of the masterbatch allowing improved processing speed;
(d) optionally up to 20 wt. % of one or more additives selected from the group consisting of lubricity agents, which improve the introduction of the cork in containers and fillers; and
(e) a blowing agent.