Thermoplastic copolymer block polyamide silicone elastomers

Abstract

A thermoplastic elastomer composition comprising a blend of (A) a thermoplastic organic polyether block amide copolymer, (B) a silicone composition comprising (B1) a silicone base comprising (B1a) a diorganopolysiloxane polymer having a viscosity of at least 1000000 mPa.Math.s at 25° C. and an average of at least 2 alkenyl groups per molecule and (B1b) a reinforcing filler in an amount of from 1 to 50% by weight based on the weight of (B1a), (B2) an organohydrido silicone compound which contains an average of at least 2 silicon-bonded hydrogen groups per molecule, (C) a hydrosilylation catalyst, and optionally: one or more additives component (D), wherein the weight ratio of thermoplastic organic polyether block amide copolymer (A) to the silicone composition (B) is in the range 50:50 to 95:5, and wherein component (B2) and (C) are present in an amount sufficient to cure said silicone composition (B1).

Claims

1. A thermoplastic elastomer composition comprising a blend of (A) a thermoplastic organic polyether block amide copolymer having a Shore D hardness of 35 to 72, (B) a silicone composition comprising (B1) a silicone base comprising (B1a) a diorganopolysiloxane polymer having a viscosity of at least 1,000,000 mPa.Math.s at 25° C. and an average of at least 2 alkenyl groups per molecule and (B1b) a reinforcing filler in an amount of from 1 to 50% by weight based on the weight of (B1a), (B2) an organohydrido silicone compound which contains an average of at least 2 silicon-bonded hydrogen groups per molecule, (C) a hydrosilylation catalyst, and optionally: one or more additives component (D), wherein the weight ratio of thermoplastic organic polyether block amide copolymer (A) to the silicone composition (B) is in the range 50:50 to 95:5, and wherein component (B2) and (C) are present in an amount sufficient to cure said silicone composition B1.

2. The thermoplastic elastomer composition according to claim 1 wherein the diorganopolysiloxane polymer (B1a) is a diorganopolysiloxane gum.

3. The thermoplastic elastomer composition according to claim 1 wherein the reinforcing filler (B1b) is silica.

4. The thermoplastic elastomer composition according to claim 3 wherein the silica reinforcing filler (B1b) is present at from 2 to 10% by weight based on the diorganopolysiloxane polymer (B1a).

5. The thermoplastic elastomer composition according to claim 3 wherein the silica reinforcing filler (B1b) is present at from 6 to 20% by weight based on the diorganopolysiloxane polymer (B1a).

6. The thermoplastic elastomer composition according to claim 1 wherein the weight ratio of a premixture of the thermoplastic organic polyether block amide copolymer (A) and the additive(s) component (D) to the silicone composition (B) is in the range 50:50 to 95:5.

7. A thermoplastic elastomer cured from the thermoplastic elastomercomposition of claim 1.

8. A part or component for sports equipment, footwear, automotive, appliances, electronics, portable electronic, electrical, communication, and medical applications wherein the part or component comprises the thermoplastic elastomer in accordance with claim 7.

9. A wearable item comprising the thermoplastic elastomer in accordance with claim 7.

10. A method of forming a wearable item, comprising: curing the thermoplastic elastomer composition of claim 1 to form the wearable item comprising a cured thermoplastic elastomer, wherein the wearable item is intended to be in contact with the skin while in use.

11. A method of forming a part or component, comprising: curing the thermoplastic composition of claim 1 into the shape of the part or component, wherein the part or component is for sports equipment, footwear, automotive, appliances, electronics, portable electronic, electrical, communication, or medical applications.

12. A process for forming a thermoplastic elastomer in accordance with claim 7 comprising contacting (A) a thermoplastic organic polyether block amide copolymer having a Shore D hardness of to 72, (B1) a silicone base comprising (B1a) a diorganopolysiloxane having a viscosity of at least 1,000,000 mPa.Math.s at 25° C. and an average of at least 2 alkenyl groups per molecule and (B1b) from 1 to 50% by weight based on the diorganopolysiloxane (B1a) of a reinforcing filler, (B2) an organohydrido silicone compound which contains an average of at least 2 silicon-bonded hydrogen groups per molecule and (C) a hydrosilylation catalyst, the weight ratio of the thermoplastic organic polyether block amide copolymer to the total weight of the silicone base (B1) and the organohydrido silicone compound (B2) is in the range 50:50 to 95:5.

13. The process according to claim 12 wherein the thermoplastic organic polyether block amide copolymer (A), the silicone base (B1), the organohydrido silicone compound (B2) and the hydrosilylation catalyst (C) are contacted at a temperature in the range 100° C. to 250° C.

14. The process according to claim 12 wherein the thermoplastic organic copolymer (A), the silicone base (B1), the organohydrido silicone compound (B2) and the hydrosilylation catalyst (C) are blended in an extruder.

15. The process according to claim 12 wherein after forming said thermoplastic elastomer is extruded, co-extruded, laminated, calendared and/or extruded-calendaring to form a thermoplastic film or a thermoplastic sheet.

Description

EXAMPLES

(1) The invention is illustrated by the following examples, in which parts and percentages are by weight unless otherwise stated.

(2) The materials used in the Examples were:

(3) Si-Rubber 1: Uncatalysed Silicone Rubber Base, comprising a vinyl-terminated diorganopolysilxane gum and silica. The base has a plasticity value of 360 mm/100 measured using a Williams Parallel plate plastimeter in accordance with ASTM D-926-08. Si-Rubber 1 is intended to have a Shore A hardness of 70 upon cure. Si-Rubber 2: Uncatalysed Silicone Rubber base, comprising a vinyl-terminated diorganopolysilxane gum and silica. The base has a plasticity value of 169 mm/100 measured using a Williams Parallel plate plastimeter in accordance with ASTM D-926-08. Si-Rubber 2 is intended to have a shore A hardness of 40 upon cure. A Silicone based catalyst solution containing adequate catalyst concentration able to cure Si Rubber bases above A Silicone based crosslinker solution containing adequate catalyst concentration able to cure Si Rubber above listed. Four alternative PEBA samples of differing physical properties were utilised and these are referred to as follows: PEBA 1: thermoplastic organic polyether block amide copolymer of 41 shore D PEBA 2: thermoplastic organic polyether block amide copolymer of 35 shore D PEBA 3: thermoplastic organic polyether block amide copolymer of 25 shore D PEBA 4: thermoplastic organic polyether block amide copolymer of 22 shore D

(4) Thermoplastic elastomers were prepared by the process of the invention. The mixing of components and vulcanisation was carried out using a twin screw extruder. The processing section was heated in a range from 160° C. up to 240° C. the screw speed was between 150 and 400 rpm Si-Rubber 1 or 2 was added to an organic thermoplastic pre-blend within the first sections of the extruder, then the cross-linker and the catalyst solution, which initiates the vulcanization of the silicone composition within the thermoplastic matrix. The proportions of materials used are shown in below tables.

(5) Test specimens for mechanical and scratch resistance testing were prepared by injection moulding. Heating temperature for injection moulding was set at 180° C. to 220° C. and mold temperature set at 40° C. The mechanical properties were tested according to international standards as set out in Tables 1, 2, 3 and 4.

(6) Gloss Measurement

(7) Gloss is determined by projecting a beam of light at a fixed intensity and angle (in this case of 60°) onto a surface of the base and measuring the amount of reflected light at an equal but opposite angle.

(8) TABLE-US-00001 TABLE 1 Unit Standard PEBA1 Ex 1 Ex. 2 Ex. 3 Ex. 4 Si-Rubber 1 with adequate curing agent solution and 0 20.87 52.8 concentration to ensure crosslinking Si Rubber 2 with adequate curing agent solution and 0 21.19 52.98 concentration to ensure crosslinking PEBA1 100 79.13 78.81 47.82 47.02 Hardness Shore A ISO 868 93.4 91.8 90.9 87.2 85.5 Tensile strength at 100% of elongation - transversal- MPa ISO 37 8.5 8.6 8.2 7.6 8.5 500 mm/min Tensile strength at 200% of elongation - transversal- MPa ISO 37 8.6 9.8 9.7 9.4 10.6 500 mm/min Tensile strength at 300% of elongation - transversal- MPa ISO 37 9.3 11.7 11.5 11.1 12.4 500 mm/min Tensile strength at break - transversal-500 mm/min MPa ISO 37 43.8 19.5 20.8 15.9 15 Elongation at break - transversal-500 mm/min % ISO 37 905 528 579 544 455 Tear strength - Transversal-500 mm/min N/mm ISO R 34/B/A 128 112.2 98.3 71.8 69.1 Flexural modulus MPa 85 76 63 46 37 Gloss B Internal 34 39 30 13 9

(9) TABLE-US-00002 TABLE 2 Unit Standard PEBA2 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Si-Rubber 1 with adequate curing agent solution and 0 20.87 52.8 concentration to ensure crosslinking Si Rubber 2 with adequate curing agent solution and 0 21.19 52.98 concentration to ensure crosslinking PEBA2 100 79.13 78.81 47.82 47.02 Hardness Shore A ISO 868 90 91 87.6 84 75.9 Tensile strength at 100% of elongation - transversal- MPa ISO 37 8.6 7.2 6.6 7.4 3.3 500 mm/min Tensile strength at 200% of elongation - transversal- MPa ISO 37 9 7.7 7.2 8.9 3.9 500 mm/min Tensile strength at 300% of elongation - transversal- MPa ISO 37 9.7 8.6 8 10.5 — 500 mm/min Tensile strength at break - transversal-500 mm/min MPa ISO 37 32.2 19.7 8.6 19.6 4.1 Elongation at break - transversal-500 mm/min % ISO 37 1000 663 347 592 244 Tear strength - Transversal-500 mm/min N/mm ISO R 34/B/A 121 91 71 57.1 37 Flexural modulus MPa 77 60 51 30 22

(10) TABLE-US-00003 TABLE 3 Unit Standard PEBA3 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Si-Rubber 1 with adequate curing agent solution and 0 20.87 52.8 concentration to ensure crosslinking Si Rubber 2 with adequate curing agent solution and 0 21.19 52.98 concentration to ensure crosslinking PEBA3 100 79.13 78.81 47.82 47.02 Hardness Shore A ISO 868 80 78.2 71.2 69.5 63.8 Tensile strength at 100% of elongation - transversal- MPa ISO 37 4.1 4 3.3 3.1 2.5 500 mm/min Tensile strength at 200% of elongation - transversal- MPa ISO 37 4.3 4.4 3.7 3.9 3.3 500 mm/min Tensile strength at 300% of elongation - transversal- MPa ISO 37 4.9 5 4.3 4.6 4.1 500 mm/min Tensile strength at break - transversal-500 mm/min MPa ISO 37 22.6 21 17.9 13.5 11.8 Elongation at break - transversal-500 mm/min % ISO 37 928 997 903 825 790 Tear strength - Transversal-500 mm/min N/mm ISO R 34/B/A 87.7 68.8 57.5 53.8 45.3 Flexural modulus MPa 20 21 15 10 8 Gloss B Internal 57 21 4.4 4.2 4.6

(11) TABLE-US-00004 TABLE 4 Unit Standard PEBA4 Ex. 13 Ex. 14 Si-Rubber 1 0 36.52 Si Rubber 2 0 37.08 PEBA4 100 PEBA3 63.48 62.92 Hardness Shore A ISO 868 74.3 74 68.9 Tensile strength at 100% of elongation - transversal- MPa ISO 37 3.1 3.5 3.1 500 mm/min Tensile strength at 200% of elongation - transversal- MPa ISO 37 3.4 4.1 3.8 500 mm/min Tensile strength at 300% of elongation - transversal- MPa ISO 37 3.8 4.8 4.5 500 mm/min Tensile strength at break - transversal-500 mm/min MPa ISO 37 18 16.4 16 Elongation at break - transversal-500 mm/min % ISO 37 875 892 861 Tear strength - Transversal-500 mm/min N/mm ISO R 34/B/A 76.4 60.4 56 Flexural modulus MPa 13 12 10 Gloss B Internal 69 10 4.4

(12) It will be seen when assessing the results of Tables 1, 2 and 3, that choice of PEBA strongly influence final hardness of material in present invention: PEBA, such as PEBA 3, permit high hardness changes (minus 16 shore A) whilst products of harder PEBAs e.g. PEBA1 when mixed with the silicone materials as hereinbefore described have a smaller effect on softness (minus 8 shore A) even for high Silicone ratio. In table 3 it will be seen that a silicone free elastomer shows an hardness limited to 74 shore A (PEBA 4), while the silicone based elastomer of present invention shows hardness down below 65 shore A.

(13) Furthermore, it will be see in the results of table 4 that different examples of present invention obtain similar flexural modulus measured at room temperature as PEBA4, even with different hardness values.

(14) Another benefit of the present invention is the important reduction of surface gloss, especially obtained for high silicone content material.

(15) Dynamic elastic shear modulus values were determined to show the viscoelastic behaviour of some example compositions and were compared with the PEBAs. A Haak Mars III apparatus was used with a frequency of 1 Hz, a 0.01% strain and temperature was varied at 2° C. per minute.

(16) TABLE-US-00005 TABLE 5 Dynamic elastic shear modulus values (Pa) Temperature Ex. 13 (Pa) PEBA4 (Pa) Ex. 14 (Pa) PEBA3 (Pa) 30° C. 4 818 648 4 990 124 6 225 682 6 466 650 40° C. 4 730 691 4 880 275 5 997 783 6 217 331 50° C. 4 571 667 4 675 203 5 679 753 6 034 158 60° C. 4 161 567 4 013 313 5 109 656 5881 113 70° C. 3 692 043 3 324 608 4 484 021 5 722 225 80° C. 3 364 241 2 817 997 4 055 901 5 496 103 90° C. 3 094 629 2 316 683 3 691 279 4 918 806 100° C.  2 735 998 1 753 919 3 249 965 3 749 101 110° C.  2 286 924 1 271 902 2 666 662 2 653 953 120° C.  1 842 744   831 911 2 097 518 1 781 328 130° C.  1 430 671   369 019 1 575 500 1 184 344 140° C.    994 200   63 769 1 040 192   704 792 temperature Ex. 1 (Pa) PEBA2 (Pa) Ex. 2 (Pa) PEBA1 (Pa) 30° C. 23 719 790 24 452 776 27 354 908 28 508 588 40° C. 23 136 094 22 043 866 26 428 888 26 980 858 50° C. 22 582 890 19 598 766 25 492 228 25 788 670 60° C. 21 768 826 16 777 978 24 349 934 24 680 264 70° C. 20 361 810 15 247 278 22 685 750 23 566 668 80° C. 17 937 730 14 259 272 19 853 482 22 303 998 90° C. 15463 817 13 473 709 17 139 140 20 641 158 100° C.  13 846 606 12 702 577 15 604 224 16 453 595 110° C.  12 909 643 11 914 165 14 507 539 12 312 737 120° C.  11 961 254 10 926 006 13 401 994  8 796 235 130° C.  10 907 904  9 718 368 12 151 919  5 372 965 140° C.   9 569 443  8 144 971 10 564 412  2 529 929

(17) An advantage of the present invention is to obtain materials with a low hardness using a hard PEBA and limiting the soft block content. This thereby maintains benefits of high hard block content such as thermal resistance, as shown in table 5 above despite the relatively low hardness. It can be seen that examples have similar dynamic elastic shear modulus at 30° C. results as pure PEBA. However, the loss of dynamic elastic shear modulus with temperature increase is less significant for material as described herein, especially at temperature above 110° C. when compared to the results for the comparative PEBAs.