Flame retardant thermoplastic elastomers

Abstract

A flame-retardant thermoplastic elastomer compound includes polyphenylene ether, a hydrogenated styrene block copolymer, at least one solid non-halogenated phosphorus containing flame retardant, a nucleated olefinic polymer, two different specific UV stabilizers, and pigment. The compound has a before-aging tensile elongation of >200% and an after-aging tensile elongation residual of at least 75% according to UL 62. The compound is useful for making an insulation layer, a jacketing layer, or both for protected electrical lines such as alternating current wire and cable products, accessory cables, and a variety of injection molded electrical or electronic parts.

Claims

1. A thermoplastic elastomer composition, comprising: (a) from about 10 to about 60 weight percent, by weight of the composition, of a polyphenylene ether; (b) from about 10 to about 60 weight percent, by weight of the composition, of a hydrogenated styrenic block copolymer; (c) from about 5 to about 30 weight percent, by weight of the composition, of at least one solid non-halogen flame retardant selected from the group consisting of organo-phosphinate, melamine polyphosphate, and combinations thereof; (d) from about 5 to about 40 weight percent, by weight of the composition, of a nucleated olefinic polymer; (e) from about 1 to about 2 weight percent, by weight of the composition, of 2,2-methylene-bis(6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl))-phenol; (f) from about 1 to about 2 weight percent, by weight of the composition, of Poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]]); and (g) from about 2 to about 10 weight percent, by weight of the composition, of titanium dioxide pigment.

2. The thermoplastic elastomer composition of claim 1, wherein the hydrogenated styrenic block copolymer has a weight average molecular weight of between about 70,000 and about 160,000 and a ratio of styrenic end-block to olefinic mid-block ranging from about 20/80 to about 40/60, wherein the composition further comprises plasticizing oil, and wherein the composition further comprises tackifier.

3. The thermoplastic elastomer composition of claim 1, wherein the hydrogenated styrenic block copolymer is selected from the group consisting of styrene-ethylene-butylene-styrene block copolymers, styrene-ethylene-propylene-styrene block copolymers, hydrogenated styrene-isoprene block copolymers, hydrogenated styrene-butadiene block copolymers, and styrene-ethylene-ethylene-propylene-styrene block copolymers, and combinations of them.

4. The thermoplastic elastomer composition of claim 1, wherein the polyphenylene ether is unblended or blended with an aromatic vinyl group thermoplastic resin.

5. The thermoplastic elastomer composition of claim 4, wherein the polyphenylene ether is selected from the group consisting of poly(2,6-dimethyl-1,4-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-propyl-1,4-phenylene ether), poly(2,6-dipropyl-1,4-phenylene ether), poly(2-ethyl-6-propyl-1,4phenylene ether), poly(2,6-dimethoxy -1,4-phenylene ether), poly(2,6-di(chloro methyl)-1,4-phenylene ether), poly(2,6-di(bromo methyl)-1,4-phenylene ether), poly(2,6-diphenyl-1,4-phenylene ether), poly(2,6-ditoluyl -1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether), poly(2,6-dibenzyl-1,4-phenylene ether), poly(2,5-dimethyl-1,4-phenylene ether), and combinations thereof.

6. The thermoplastic elastomer composition of claim 5, wherein the aromatic vinyl group thermoplastic resin is selected from the group consisting of homopolymers of styrene or its derivatives, copolymers of styrene and p-methyl styrene, copolymers of styrene and alpha-methyl styrene, copolymers of styrene and alpha-methyl-p-methyl styrene, copolymers of styrene and chlorostyrene, copolymers of styrene and bromostyrene, and combinations thereof.

7. The thermoplastic elastomer composition of claim 1, wherein the solid non-halogen flame retardant is an organo-phosphinate and wherein the composition further comprises polyammonium polyphosphate.

8. The thermoplastic elastomer composition of claim 1, wherein the nucleated olefinic polymer is nucleated polypropylene homopolymer.

9. The thermoplastic elastomer composition of claim 1, wherein the composition further comprises one or more additives selected from the group consisting of adhesion promoters; antioxidants; biocides, antibacterials, fungicides, and mildewcides ; anti-fogging agents; anti-static agents; bonding, blowing or foaming agents; dispersants; fillers or extenders; smoke suppresants; expandable char formers; impact modifiers; initiators; lubricants; micas; processing aids; release agents; silanes, titanates or zirconates; slip or anti-blocking agents; stabilizers; stearates; tackifiers; viscosity regulators; waxes; and combinations of them.

10. The thermoplastic elastomer composition of claim 1 in the form of an insulation layer enveloping a protected electrical line or in the form of a jacketing layer enveloping a protected electrical line.

11. A plastic article made from the thermoplastic elastomer composition of claim 1.

12. The plastic article of claim 11, wherein the plastic article has a Delta E color variation of less than 1 after 10 days of QUV testing according to ASTM D4587 (UVA, 340 nm, 0.77 watt/m.sup.2, 60 C. for 8 hours light and 50 C. for 4 hours dark condensation).

13. The plastic article of claim 11, in the form of an electrical part or an electronic part.

14. A protected electrical line, comprising: (a) wire or cable having an axial length and (b) at least one layer of the thermoplastic elastomer composition of claim 1 enveloping the axial length of the wire or cable.

15. The protected electrical line of claim 14, wherein the protected electrical line has a Delta E color variation of less than 1 after 10 days of QUV testing according to ASTM D4587 (UVA, 340 nm, 0.77 watt/m.sup.2, 60 C. for 8 hours light and 50 C. for 4 hours dark condensation).

16. The protected electrical line of claim 14 in the form of a wire.

17. The protected electrical line of claim 14 in the form of a cable.

Description

EXAMPLES

(1) All Examples of United States Patent Application Publication No. 20120037396 (Gu) are expressly incorporated by reference herein. This invention used one embodiment from the Gu Patent Application Publication No. 20120037396, a TPE compound, branded as LC370-195 grade TPE from PolyOne Corporation. Without undue experimentation, a person having ordinary skill in the art can utilize the UV resistance improvements of this invention with any of the embodiments identified or contemplated in the Gu Patent Application Publication No. 20120037396.

(2) Table 2 shows sources of ingredients for the examples of UV light resistance. Table 3 shows the formulations of the masterbatches of UV light stabilizers to be later combined with the LC370-195 grade TPE described above. The performance requirement for success was less than 1.0 Delta E variation after 10 days of exposure to QUV light testing, according to the procedures and equipment specified in ASTM D4587 (UVA, 340 nm, 0.77 watt/m.sup.2, 60 C. for 8 hours light and 50 C. for 4 hours dark condensation).

(3) The masterbatches were made by 25mm twin screw extrustion with the barrel and die temperatures ranged from 170 C. (338 F.) to 180 C. (356 F.) with the melt temperature of 196 C. (382 F.). The pre-mixing was performed with a Sack Mixer to get the uniform distribution of the additives with mild mixing speed for one minute. A 20/60/20 screen pack was used to generate back pressure and improve the dispersion quality. The vacuum was applied in one of the barrel zones to remove volatiles during extrusion.

(4) The molded chips for QUV testing were made by injection molding with the temperature setup rangeing from 160 C. (320 F.) to 190 C. (374 F.). The mold temperature was maintained as cool with water circulation. The mold chip dimension was 6.35 cm8.89 cm (2.5 inch3.5 inch) with a set of stepwise thicknesses that was 0.15 cm (60 mil) at the top of the mold chip and 0.076 cm (30 mil) thickness at the bottom of the mold chip. The masterbatches were pre-blended with the FR TPE by a bag shaking and fed into the injection molding hopper. The color reading was performed on the flat side of the mold chips (the side opposite the side having different thickness dimensions identified above) before and after QUV testing.

(5) TABLE-US-00003 TABLE 2 Ingredients Chemical Name or Description Purpose Commercial Source 1% Areosperse black pigment + 99% Ethylene Bis Black pigment in Wax PolyOne Stearamide Wax 3,5-di-t-Butyl-4-Hydroxybenzoic Acid, Hexadecyl Light Stabilizer Cytec Ester (Cyasorb UV-2908) 4-piperidol,2,2,6,6- tetramethyl- RPW stearin Hinder Amine Light Cytec (fatty acids mixture) (Cyasorb UV 3853S) Stabilizer Amines, bis(hydrogenated tallow alkyl), oxidized/ Phenol free processing BASF PHENOL, 2,4-BIS(1,1-DIMETHYLETHYL)-, stabilizer PHOSPHITE (3:1) (Irgastab FS 301FF) system/Antioxidant Bis(2.4-di-tert-butylphenyl) pentaerythritol Stabilizer/Antioxidant Songwon diphosphite (Songnox 6260 PW) Phenol, 2,2-methylene-bis(6-(2H-benzotriazol-2- Very low volatile BASF yl)-4-(1,1,3,3-tetramethylbutyl)) (Tinuvin 360) benzotriazole UV absorber Phenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1- Very low volatile BASF methyl-1-phenylethyl) (Tinuvin 234) benzotriazole UV absorber Poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5- Oligomeric Hindered BASF triazine-2,4-diyl][(2,2,6,6-tetramethyl-4- Amine Light Stabilizer piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6- (HALS) tetramethyl-4-piperidinyl)imino]]) (Chimassorb 944 FDL (Beads)) Polypropylene (PROFAX 6301 PP FLAKE) Carrier Resin Basell Sodium Alumino Sulphosilicate Blue Pigment Blue Pigment NUBIOLA USA Blue 29 Sodium Aluminosilicate Violet Pigment Violet 15 Violet Pigment NUBIOLA USA (Nubix V-8) Substituted Amine Oligomer (Cyasorb UV-3529) Light Stabilizer Cytec Substituted Heterocycle of S-Triazine Class Light Absorber Cytec (Cyasorb UV 1164) Titanium Dioxide (Tiona 696) Weatherable White pigment CRISTAL INORGANIC CHEMICALS SWITZERLAND Titanium Dioxide (Tronox 470) White pigment HUNTSMAN TIOXIDE/CRISTAL INORGANIC CHEMICALS SWITZERLAND Tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-s- Antioxidant Cytec triazine-2,4,6-(1H,3H, 5H)-trione (Cyanox 1790) Tris(2,4-di-tert-butylphenyl) phosphite/ Antioxidant/Stabilizer Songwon Tetrakis[methylene(3,5-di-tert-butyl-4- hydroxyhydrocinnamate)] methane (Songnox 11B PW)

(6) TABLE-US-00004 TABLE 3 Masterbatch Formulations Ingredients M-1 M-2 M-3 M-4 M-5 M-6 Titanium Dioxide (Tronox 470) 50 Titanium Dioxide (Tiona 696) 50 50 50 36.71 Sodium Aluminosilicate Violet Pigment Violet 15 (Nubix V-8) 1.8 1.8 1.8 1.8 1.62 1% Areosperse black pigment + 99% Ethylene Bis 0.5 0.5 0.5 0.5 0.44 Stearamide Wax Sodium Alumino Sulphosilicate Blue 0.94 0.94 0.94 0.94 0.66 Pigment Blue 29 Amines, bis(hydrogenated tallow alkyl), oxidized/PHENOL, 0.72 0.42 2,4-BIS(1,1-DIMETHYLETHYL)-, PHOSPHITE (3:1) (Irgastab FS 301FF) Phenol, 2,2-methylene-bis(6-(2H-benzotriazol-2-yl)-4- 8.57 17.14 10 (1,1,3,3-tetramethylbutyl)) (Tinuvin 360) Phenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1- 4.29 phenylethyl) (Tinuvin 234) Poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4- 8.57 4.29 17.14 10 diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6- hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]]) (Chimassorb 944 FDL (Beads)) Tris(2,4-di-tert-butylphenyl)phosphite/ 2.85 1.43 Tetrakis[methylene(3,5-di-tert-butyl-4- hydroxyhydrocinnamate)] methane (Songnox 11B PW) Bis(2.4-di-tert-butylphenyl) pentaerythritol diphosphite 2.14 2.86 (Songnox 6260 PW) Tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine- 0.71 2,4,6-(1H,3H,5H)-trione (Cyanox 1790) Substituted Heterocycle of S-Triazine Class (Cyasorb UV 5.71 5.71 1164) Substituted Amine Oligomer (Cyasorb UV-3529) 5.71 5.71 4-piperidol,2,2,6,6- tetramethyl- RPW stearin (fatty acids 5.71 7.14 mixture) (Cyasorb UV 3853S) 3,5-di-t-Butyl-4-Hydroxybenzoic Acid, Hexadecyl Ester 2.86 (Cyasorb UV-2908) Polypropylene (PROFAX 6301 PP FLAKE) 26.78 22.48 26.77 36.75 65 40.15 100 100 100 100 100 100

(7) TABLE-US-00005 TABLE 4 TPE Compound Formulations and Test Results Weight Percent A B C D E F 1 G 2 LC370-195 TPE (PolyOne) 100 93 93 93 93 86 86 93 88 M-1 7 M-2 7 M-3 7 14 M-4 7 14 M-5 7 M-6 12 Total 100 100 100 100 100 100 100 100 100 Wt. % of Tinuvin 360 1.2 1.2 1.2 Wt. % of Chimassorb 944 FDL 1.2 1.2 1.2 QUV After Day 1 5.85 No Data 3.27 0.23 0.32 0.23 0.62 5.26 0.98 QUV After Day 2 6.02 3.30 No Data 0.63 1.48 0.38 0.60 3.46 0.76 QUV After Day 3 9.45 4.57 No Data 2.79 2.66 0.99 No Data 4.24 0.73 QUV After Day 4 12.56 No Data No Data 3.74 4.56 1.91 0.72 4.04 0.63 QUV After Day 5 No Data No Data No Data 1.83 5.52 2.46 0.25 No Data No Data QUV After Day 6 No Data No Data No Data 2.41 6.79 3.35 0.41 No Data No Data QUV After Day 7 18.68 No Data No Data 2.42 8.10 3.95 0.29 6.82 0.72 QUV After Day 8 20.53 No Data No Data 2.99 9.12 4.76 0.21 7.63 0.66 QUV After Day 9 21.00 No Data No Data No Data No Data No Data 7.43 0.46 QUV After Day 10 21.67 8.41 No Data No Data No Data No Data No Data 0.88

(8) Eight different TPE compound formulations were tested before one of UV stabilizer masterbatches was found to satisfy the requirement of less than 1 Delta E variation after 10 days of continuous QUV exposure according to the requirements of ASTM D4587 (UVA, 340 nm, 0.77 watt/m.sup.2, 60 C. for 8 hours light and 50 C. for 4 hours dark condensation).

(9) Comparative Example A was a control with no UV stabilizer masterbatch added. Its performance after even one day was unsatisfactory and after 10 days was horrible.

(10) Comparative Examples B and C, using masterbatches M-1 and M-2 at a letdown ratio of 7%, were all failures, despite the selection of conventional UV stabilizers such as the Cyasorb UV stabilizers and the Cyanox UV stabilizer.

(11) Comparative Example D and Example 1 introduced the use of Tinuvin 360 UV stabilizer and Chimassorb 944 FDL UV stabilizer. While Comparative Example D was insufficient in amount because of its letdown ratio of 7% (resulting in the Tinuvin 360 UV stabilizer and Chimassorb 944 FDL UV stabilizer each being present at about 0.6 weight percent), Example 1 did show acceptable Delta E values and therefore served as a launching point for Comparative Example H and Example 1 identified below, to adjust to a different color for matching purposes.

(12) Comparative Examples E and F were failures because Tinuvin 234 was used instead of Tinuvin 360, even at two different letdown ratios and even though Chimassorb 944 FDL UV stabilizer was also used.

(13) Comparative Example G used Irgastab Antioxidant instead of Songnox Antioxidant (to better resist gas fading) as ingredients but maintained the same usage of Tinuvin 360 UV stabilizer and Chimassorb 944 FDL UV stabilizer. Significantly, without the pigments also present as in the other masterbatches, this un-pigmented compound failed. Thus, Example 2 which restored the pigments to the UV stabilization ingredients yielded an unpredictable result.

(14) From the results of the Comparative Example G and Examples 1 and 2, it can be possible to use any amount of Tinuvin 360 UV stabilizer above about 1 weight percent and preferably above about 1.2 weight percent of the total compound. Likewise, it can be possible to use any amount of Chimassorb 944 FDL UV stabilizer above about 1 weight percent and preferably above about 1.2 weight percent of the total compound. At some level of both UV stabilizers, their cost will exceed their benefit. For purposes of this invention, any amount above about 1 weight percent and that excessive amount for either UV stabilizer is considered effective.

(15) It should also be noted that all masterbatches except M-1 utilized a weather-resistant titanium dioxide pigment, Tiona 696 pigment. A weather-resistant white pigment is required for these formulations but may not be required for other formulations to be established using this invention.

(16) Without undue experimentation, a person having ordinary skill in the art can utilize TPE compounds having UV resistance unexpectedly found from the use of Tinuvin 360 UV stabilizer and Chimassorb 944 FDL UV stabilizer to make insulation or jacketing for protected electrical line (wire, cable, or both) which can pass the UL 62 test and have less than 1 Delta E color variation after 10 days of QUV testing according to ASTM D4587 (UVA, 340 nm, 0.77 watt/m.sup.2, 60 C. for 8 hours light and 50 C. for 4 hours dark condensation). Also, these Examples inform the art of these compounds being suitable for injected molded TPE-based plastic articles which need flame retardance and UV resistance.

(17) The invention is not limited to the above embodiments. The claims follow.