Profile extrusion method with reduced die build-up and extruded article prepared thereby

1. A method of reducing die lip build-up during profile extrusion of a thermoplastic article, comprising:

profile extruding through a die a thermoplastic composition having a temperature of 220 to 240° C.; and

cooling the extruded composition to form an extruded thermoplastic article;

wherein the thermoplastic composition comprises

56 to 62 weight percent of a poly(arylene ether),

16 to 22 weight percent of a homopolystyrene,

7 to 13 weight percent of a hydrogenated block copolymer of an alkenyl aromatic compound and a conjugated diene, and

7 to 13 weight percent of a triaryl phosphate;

wherein the thermoplastic composition comprises less than 1 weight percent of unhydrogenated poly(conjugated diene) rubber;

wherein all weight percents are based on the total weight of the thermoplastic composition;

wherein the thermoplastic composition exhibits

an Izod notched impact strength at −30° C. of at least 6 kilojoules/meter 2 , as measured according to ISO 180 using notch configuration A, and

a Vicat B value of at least 125° C., measured according to ISO 306, Method B120;

wherein the profile extruding the thermoplastic composition produces an average die lip build-up per hour measured over the course of 8 continuous hours of profile extrusion of the thermoplastic composition, measured at a melt temperature of 233° C. using an annular die having an outside diameter of 24.6 millimeters and an inside diameter of 21.35 millimeters; and wherein the average die lip build-up is less than that produced by a corresponding thermoplastic composition in which the hydrogenated block copolymer is replaced by an equal weight of an unhydrogenated block copolymer.

2. The method of claim 1 , wherein the average die lip build-up per hour measured over the course of 8 continuous hours of profile extrusion of the thermoplastic composition is less than or equal to 5 milligrams per hour.

3. The method of claim 1 , wherein the average die lip build-up per hour measured over the course of 8 continuous hours of profile extrusion of the thermoplastic composition is 1 to 5 milligrams per hour.

4. The method of claim 1 , wherein the hydrogenated block copolymer of an alkenyl aromatic compound and a conjugated diene is a polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer.

5. The method of claim 1 , wherein the thermoplastic composition further comprises 0.5 to 5 weight percent of an ethylene-butene copolymer having a viscosity average molecular weight of 3,500 to 6,000 atomic mass units, and a density of 0.88 to 0.92 gram/milliliter.

6. The method of claim 1 , wherein the thermoplastic composition further comprises 0.025 to 0.5 weight percent of a copolymer of vinylidene fluoride and hexafluoropropylene having a fluorine content of 60 to 70 weight percent based on the total weight of the copolymer.

7. The method of claim 1 , wherein the thermoplastic composition further comprises 3 to 9 weight percent titanium dioxide.

8. The method of claim 1 , wherein the thermoplastic composition exhibits at least one of

a flexural strength of at least 95 megapascals, measured at 23° C. according to ISO 178,

a notched Izod impact strength of at least 20 kilojoules/meter 2 , measured at 23° C. according to ISO 180 using notch configuration A,

a Charpy notched impact strength of at least 20 kilojoules/meter 2 , measured at 23° C. according to ISO 179 using notch type A, and

a tensile strength at yield of at least 60 megapascals, measured at 23° C. according to ISO 527.

9. The method of claim 1 ,

wherein the thermoplastic composition comprises

57 to 61 weight percent of the poly(arylene ether),

17 to 21 weight percent of the homopolystyrene,

8 to 12 weight percent of the hydrogenated block copolymer, wherein the hydrogenated block copolymer comprises a polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer,

8 to 12 weight percent of the triaryl phosphate;

wherein the thermoplastic composition further comprises

3 to 9 weight percent titanium dioxide, and

1 to 3 weight percent of an ethylene-butene copolymer having a viscosity average molecular weight of 3,500 to 6,000 atomic mass units, a density of 0.88 to 0.92 gram/milliliter, and a viscosity of 1,000 to 1,500 millipascal-seconds at 140° C.;

wherein the thermoplastic composition comprises less than 0.5 weight percent of unhydrogenated poly(conjugated diene) rubber;

wherein the thermoplastic composition exhibits

an Izod notched impact strength at −30° C. of 6 to 12 kilojoules/meter 2 , and

a Vicat B value of 125 to 145° C., measured according to ISO 306, Method B120;

wherein the average die lip build-up per hour measured over the course of 8 continuous hours of profile extrusion of the thermoplastic composition is 1 to 5 milligrams per hour; and

wherein the thermoplastic composition exhibits at least one of

a flexural strength of 95 to 100 megapascals, measured at 23° C. according to ISO 178,

a notched Izod impact strength of 20 to 25 kilojoules/meter 2 , measured at 23° C. according to ISO 180 using notch configuration A,

a Charpy notched impact strength of 20 to 30 kilojoules/meter 2 , measured at 23° C. according to ISO 179 using notch type A, and

a tensile strength at yield of 60 to 70 megapascals, measured at 23° C. according to ISO 527.

10. The method of claim 1 , wherein the thermoplastic composition consists of

the poly(arylene ether),

the homopolystyrene,

the hydrogenated block copolymer,

the triaryl phosphate,

optionally, 0.5 to 5 weight percent of an ethylene-butene copolymer having a viscosity average molecular weight of 3,500 to 6,000 atomic mass units, and a density of 0.88 to 0.92 gram/milliliter,

optionally, 0.025 to 0.5 weight percent of a copolymer of vinylidene fluoride and hexafluoropropylene having a fluorine content of 60 to 70 weight percent based on the total weight of the copolymer,

optionally, 3 to 9 weight percent titanium dioxide,

optionally, 0.5 to 10 weight percent of a metal hydroxide, and

optionally, one or more additives known in the thermoplastic arts, including, for example, stabilizers, antioxidants, mold release agents, drip retardants, nucleating agents, UV blockers, dyes, pigments, fragrances, anti-static agents, mineral oil, metal deactivators, antiblocking agents, fillers having a particle size less than or equal to 5 micrometers, and combinations thereof.

11. The method of claim 4 , wherein the polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer is provided in the form of a masterbatch comprising 50 to 95 weight percent of the polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer and 5 to 50 weight percent poly(arylene ether), based on the total weight of the masterbatch.

12. The method of claim 6 , wherein the copolymer of vinylidene fluoride and hexafluoropropylene is provided in the form of a masterbatch comprising 2 to 10 weight percent of the copolymer of vinylidene fluoride and hexafluoropropylene and 90 to 98 weight percent low density polyethylene, based on the total weight of the masterbatch.

13. A profile extruded article, produced by a process comprising:

profile extruding through a die a thermoplastic composition having a temperature of 220 to 240° C.; and

cooling the extruded composition to form an extruded thermoplastic article;

wherein the thermoplastic composition comprises

56 to 62 weight percent of a poly(arylene ether),

16 to 22 weight percent of a homopolystyrene,

7 to 13 weight percent of a hydrogenated block copolymer of an alkenyl aromatic compound and a conjugated diene, and

7 to 13 weight percent of a triaryl phosphate;

wherein the thermoplastic composition comprises less than 1 weight percent of unhydrogenated poly(conjugated diene) rubber;

wherein all weight percents are based on the total weight of the thermoplastic composition;

wherein the thermoplastic composition exhibits

an Izod notched impact strength at −30° C. of at least 6 kilojoules/meter 2 , as measured according to ISO 180 using notch configuration A, and

a Vicat B value of at least 125° C., measured according to ISO 306, Method B120;

wherein profile extrusion of the thermoplastic composition over the course of 8 continuous hours produces an average die lip build-up per hour less than or equal to 5 milligrams per hour, measured at a melt temperature of 233° C. using an annular die having an outside diameter of 24.6 millimeters and an inside diameter of 21.35 millimeters; and

wherein the profile extruded article is substantially free of visible residue of die lip build-up.

14. The profile-extruded article of claim 13 ,

wherein the thermoplastic composition comprises

57 to 61 weight percent of the poly(arylene ether),

17 to 21 weight percent of the homopolystyrene,

8 to 12 weight percent of the hydrogenated block copolymer, wherein the hydrogenated block copolymer comprises a polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer,

8 to 12 weight percent of the triaryl phosphate;

wherein the thermoplastic composition further comprises

3 to 9 weight percent titanium dioxide, and

1 to 3 weight percent of an ethylene-butene copolymer having a viscosity average molecular weight of 3,500 to 6,000 atomic mass units, a density of 0.88 to 0.92 gram/milliliter, and a viscosity of 1,000 to 1,500 millipascal-seconds at 140° C.;

wherein the thermoplastic composition comprises less than 0.5 weight percent of unhydrogenated poly(conjugated diene) rubber;

wherein the thermoplastic composition exhibits

an Izod notched impact strength at −30° C. of 6 to 12 kilojoules/meter 2 , and

a Vicat B value of 125 to 145° C., measured according to ISO 306, Method B120;

wherein the die lip build-up produced by the thermoplastic composition is 1 to 5 milligrams per hour; and

wherein the thermoplastic composition exhibits at least one of

a flexural strength of 95 to 100 megapascals, measured at 23° C. according to ISO 178,

a notched Izod impact strength of 20 to 25 kilojoules/meter 2 , measured at 23° C. according to ISO 180 using notch configuration A,

a Charpy notched impact strength of 20 to 30 kilojoules/meter 2 , measured at 23° C. according to ISO 179 using notch type A, and

a tensile strength at yield of 60 to 70 megapascals, measured at 23° C. according to ISO 527.

15. The profile extruded article of claim 13 , wherein the thermoplastic composition consists of

the poly(arylene ether),

the homopolystyrene,

the hydrogenated block copolymer,

the triaryl phosphate,

optionally, 0.5 to 5 weight percent of an ethylene-butene copolymer having a viscosity average molecular weight of 3,500 to 6,000 atomic mass units, and a density of 0.88 to 0.92 gram/milliliter,

optionally, 0.025 to 0.5 weight percent of a copolymer of vinylidene fluoride and hexafluoropropylene having a fluorine content of 60 to 70 weight percent based on the total weight of the copolymer,

optionally, 3 to 9 weight percent titanium dioxide,

optionally, 0.5 to 10 weight percent of a metal hydroxide, and

optionally, one or more additives known in the thermoplastic arts, including, for example, stabilizers, antioxidants, mold release agents, drip retardants, nucleating agents, UV blockers, dyes, pigments, fragrances, anti-static agents, mineral oil, metal deactivators, antiblocking agents, fillers having a particle size less than or equal to 5 micrometers, and combinations thereof.