THERMOPLASTIC ELASTOMER GEL

Abstract

A thermoplastic elastomer (TPE) compound is disclosed which has very low hardness by virtue of the use of a combination of high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer, a conventional styrene-ethylene-ethylene-propylene-styrene copolymer, and a plasticizer. Super-soft extruded or molded plastic articles may be formed from pellets of the compound, with a resulting Shore OO Hardness of between about 35 to about 52. Molded articles may be prepared using injection molding techniques.

Claims

1. A thermoplastic elastomer gel compound comprising: (a) a high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer; (b) a conventional styrene-ethylene-ethylene-propylene-styrene copolymer; and (c) a plasticizer; wherein the styrene content of the high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer is greater than 35% by weight of the high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer and the styrene content of the conventional styrene content styrene-ethylene-ethylene-propylene-styrene copolymer is less than 35% by weight of the conventional styrene content styrene-ethylene-ethylene-propylene-styrene copolymer.

2. The compound of claim 1, wherein the ratio of high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer:conventional styrene-ethylene-ethylene-propylene-styrene copolymer is about 90:10.

3. The compound of claim 1, wherein the ratio of high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer:conventional styrene-ethylene-ethylene-propylene-styrene copolymer is about 80:20.

4. The compound of claim 1, wherein the ratio of high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer:conventional styrene-ethylene-ethylene-propylene-styrene copolymer is about 70:30.

5. The compound of claim 1, wherein the ratio of high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer:conventional styrene-ethylene-ethylene-propylene-styrene copolymer is about 60:40.

6. The compound of claim 1, wherein the ratio of high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer:conventional styrene-ethylene-ethylene-propylene-styrene copolymer is about 50:50.

7. The compound of claim 1, wherein the high styrene content styrene-ethylene-ethylene-propylene-styrene copolymer is Septon™ J3341.

8. The compound of claim 1, wherein the conventional styrene-ethylene-ethylene-propylene-styrene copolymer is selected from the group consisting of Septon™ 4033; Septon™ 4044; Septon™ 4055; or combinations of two or more thereof.

9. The compound of claim 1, wherein the plasticizer oil is a mineral oil.

10. The compound of claim 1, wherein the Shore OO Hardness of the compound ranges from about 35 to about 52.

11. The compound of claim 1, wherein the compression set of the compound ranges from about 7 to about 13.

12. The compound of claim 1, wherein the viscosity @1340.5/sec of the compound ranges from about 22 to about 27.

13. The compound of claim 1, further comprising adhesion promoters; biocides; anti-fogging agents; anti-static agents; bonding, blowing and foaming agents; dispersants; fillers and extenders; fire and flame retardants and smoke suppressants; impact modifiers; initiators; lubricants; micas; pigments, colorants and dyes; additional plasticizers; processing aids; release agents; silanes, titanates and zirconates; slip and anti-blocking agents; stabilisers; stearates; ultraviolet light absorbers; viscosity regulators; waxes; and combinations of them.

14. A thermoplastic article, comprising the compound of claim 1.

15. The article of claim 14, wherein the Shore OO Hardness of the article ranges from about 35 to about 52.

16. The article of claim 14, wherein the article is injection molded.

17. A method of molding the compound of claim 1, comprising the steps of: (a) placing the compound into a drum dispensing unit; (b) heating the compound a bulk melter; (c) heating the compound along a dispensing hose; (d) heating the compound at a dispensing nozzle; and (e) dispensing the compound into a mold.

18. The method of claim 16, wherein the heating of steps (b), (c), and (d) occur at a temperature ranging from about 120° C. to about 240° C.

19. The method of claim 17, wherein the mold is an open faced mold cavity.

20. The method of claim 17, wherein the mold is a closed mold cavity with sufficient venting to allow air to be displaced.

Description

EXAMPLES

[0043] Examples provide data for evaluation of the unpredictability of this invention.

[0044] Table 2 shows the list of ingredients in the Examples and Comparative Examples.

TABLE-US-00002 TABLE 2 Brand Commercial Ingredient Name Purpose Name Source Polystyrene-polyethylene- Elastomer Septon Kuraray Co., ethylene-propylene- J3341 LTD. polystyrene copolymer Polystyrene-polyethylene- Elastomer Septon Kuraray Co., ethylene-propylene- 4055 LTD. polystyrene copolymer Polystyrene-polyethylene- Elastomer Septon Kuraray Co., ethylene-propylene- 4044 LTD. polystyrene copolymer Polystyrene-polyethylene- Elastomer Septon Kuraray Co., ethylene-propylene- 4033 LTD. polystyrene copolymer Mineral Oil Plasticizer Puretol Petro-Canada 10 Lubricants, Inc. Blue color Colorant Trans PolyOne Blue Tris(2,4-ditert- Antioxident Irgafos BASF butylphenyl)phosphite 168 Pentaerythritol Tetrakis(3- Antioxidant Irganox BASF (3,5-di-tert-butyl-4- 1010 hydroxyphenyl)propionate)

[0045] Table 3 shows the recipes for the Examples, Table 4 shows the method for making the Examples, and Table 5 shows the physical characteristics of the Examples.

TABLE-US-00003 TABLE 3 Example Example Example Example Example Example Ingredient 1 2 3 4 5 6 Formulations (ppw) Septon J3341 100 90 70 Septon 4055 100 10 30 Septon 4044 100 Septon 4033 100 Puretol 10 235 235 235 235 235 235 Trans Blue 0.9 0.9 0.9 0.9 0.9 0.9 Irgafos 168 2.75 2.75 2.75 2.75 2.75 2.75 Irganox 1010 2.75 2.75 2.75 2.75 2.75 2.75

TABLE-US-00004 TABLE 4 Example Example Example Example Example Example 1 2 3 4 5 6 Henschel Mixing Conditions Mixing Twin Twin Twin Twin Twin Twin Equipment Screw Screw Screw Screw Screw Screw extruder extruder extruder extruder extruder extruder Mixing 180 180 180 180 180 180 Temp. (° C.) Mixing 500 500 500 500 500 500 Speed (rpm) Order of Altogether Altogether Altogether Altogether Altogether Altogether Addition of Ingredients Form of Product Pellets Pellets Pellets Pellets Pellets Pellets After Mixing

TABLE-US-00005 TABLE 5 Example Example Example Example Example Example 1 2 3 4 5 6 Properties Shore OO Hardness 32.4 46.8 52.5 57.5 34.6 37 (ASTM D2240, 10 s delay) Specific gravity 0.866 0.862 0.859 0.863 0.866 0.865 (ASTM D792) Capillary Rheometer 200 200 200 200 200 200 test temperature (° C.) Viscosity @ 24.2 41.8 27.8 8.9 25 31.9 1340.5/sec (Pa .Math. s) Viscosity @ 208.7 590.1 113.8 205.1 228.7 334.8 67/sec (Pa .Math. s) Compression set test 23 23 23 23 23 23 temperature (° C.) Compression set (%) 10 12.6 10 80.9 15.3 13.4 Aesthetics of the Poor Poor Poor Poor Good Excellent molded plaque

[0046] Table 6 shows the recipes for additional Examples, Table 7 shows the method for making additional Examples, and Table 8 shows the physical characteristics of the additional Examples.

TABLE-US-00006 TABLE 6 Example Example Example Example Example Example Ingredient 7 8 9 10 11 12 Formulations (ppw) Septon J3341 50 30 10 90 70 50 Septon 4055 50 70 90 Septon 4044 10 30 50 Septon 4033 Puretol 10 235 235 235 235 235 235 Trans Blue 0.9 0.9 0.9 0.9 0.9 0.9 Irgafos 168 2.75 2.75 2.75 2.75 2.75 2.75 Irganox 1010 2.75 2.75 2.75 2.75 2.75 2.75

TABLE-US-00007 TABLE 7 Example Example Example Example Example Example 7 8 9 10 11 12 Henschel Mixing Conditions Mixing Twin Twin Twin Twin Twin Twin Equipment Screw Screw Screw Screw Screw Screw extruder extruder extruder extruder extruder extruder Mixing 180 180 180 180 180 180 Temp. (° C.) Mixing 500 500 500 500 500 500 Speed (rpm) Order of Altogether Altogether Altogether Altogether Altogether Altogether Addition of Ingredients Form of Product Pellets Pellets Pellets Pellets Pellets Pellets After Mixing

TABLE-US-00008 TABLE 8 Example Example Example Example Example Example 7 8 9 10 11 12 Properties Shore OO Hardness 40.5 43.8 45.8 35.8 40.5 44.2 (ASTM D2240, 10 s delay) Specific gravity 0.865 0.863 0.862 0.864 0.863 0.863 (ASTM D792) Capillary Rheometer 200 200 200 200 200 200 test temperature (° C.) Viscosity @ 33.3 37 40.6 22.9 25.4 24.4 1340.5/sec (Pa .Math. s) Viscosity @ 398.5 571 594.7 202.7 175.6 157.7 67/sec (Pa .Math. s) Compression set test 23 23 23 23 23 23 temperature (° C.) Compression set (%) 12.4 17 13.6 11.5 12.6 7.8 Aesthetics of the Good Poor Poor Good Excellent Good molded plaque

[0047] Table 9 shows the recipes for additional Examples, Table 10 shows the method for making additional Examples, and Table 11 shows the physical characteristics of the additional Examples.

TABLE-US-00009 TABLE 9 Example Example Example Example Example Example Example 13 14 15 16 17 18 19 Formulation (ppw) Septon J3341 30 10 90 70 50 30 10 Septon 4055 Septon 4044 70 90 Septon 4033 10 30 50 70 90 Puretol 10 235 235 235 235 235 235 235 Trans Blue 0.9 0.9 0.9 0.9 0.9 0.9 0.9 Irgafos 168 2.75 2.75 2.75 2.75 2.75 2.75 2.75 Irganox 1010 2.75 2.75 2.75 2.75 2.75 2.75 2.75

TABLE-US-00010 TABLE 10 Example Example Example Example Example Example Example 13 14 15 16 17 18 19 Henschel Mixing Conditions Mixing Twin Twin Twin Twin Twin Twin Twin Equipment Screw Screw Screw Screw Screw Screw Screw extruder extruder extruder extruder extruder extruder extruder Mixing 180 180 180 180 180 180 180 Temp. (° C.) Mixing 500 500 500 500 500 500 500 Speed (rpm) Order of Altogether Altogether Altogether Altogether Altogether Altogether Altogether Addition of Ingredients Form of Product Pellets Pellets Pellets Pellets Pellets Pellets Pellets After Mixing

TABLE-US-00011 TABLE 11 Example Example Example Example Example Example Example 13 14 15 16 17 18 19 Properties Shore OO Hardness 48.3 51.2 37.3 44.6 48 53 56 (ASTM D2240, 10 s delay) Specific gravity 0.861 0.861 0.866 0.864 0.863 0.861 0.861 (ASTM D792) Capillary Rheometer 200 200 200 200 200 200 200 test temperature (° C.) Viscosity @ 25.5 26.7 25.2 19.3 10 10.8 9.3 1340.5/sec (Pa .Math. s) Viscosity @ 137.2 132.8 302 224.6 132.9 165.6 172.9 67/sec (Pa .Math. s) Compression set test 23 23 23 23 23 23 23 temperature (° C.) Compression set (%) 8.8 12 16.5 52.4 57 68.8 68.8 Aesthetics of the Good Poor Good Good Excellent Good Poor molded plaque

[0048] The test results show that using only high styrene content SEEPS polymer or only a conventional SEEPS polymer do not result in a gel compound that exhibits the desired physical characteristics of the present technology. Conversely, compounds with a combination of high styrene content SEEPS copolymer and conventional SEEPS copolymer produce a thermoplastic elastomer with good physical characteristics.

[0049] In an embodiment, combining a high styrene content SEEPS copolymer with a medium molecular weight conventional SEEPS copolymer may provide the most desired results. In an embodiment, when the ratio is a higher high styrene content SEEPS copolymer to a conventional SEEPS copolymer amount, the resulting thermoplastic elastomer has good physical characteristics. In an embodiment, this may be any appropriate ratio, including, but not limited to, 90:10 high styrene content SEEPS copolymer:conventional SEEPS copolymer; 80:20 high styrene content SEEPS copolymer:conventional SEEPS copolymer; 70:30 high styrene content SEEPS copolymer:conventional SEEPS copolymer; 60:40 high styrene content SEEPS copolymer:conventional SEEPS copolymer; or even 50:50 high styrene content SEEPS copolymer:conventional SEEPS copolymer. When the ratio changes, the physical properties, e.g., viscosity, compression set and hardness of the gel may not change in correspondingly similar linear fashion.

[0050] The high styrene content SEEPS copolymer may not provide desired physical characteristics without a conventional SEEPS copolymer as the high styrene content SEEPS copolymer on its own has a fast setup in a melt, even if its capillary viscosity is not high. Therefore, the combination of the copolymers provides an unexpected result of a gel compound with desired physical properties, including, but not limited to, good viscosity, compression set and hardness. Further, the gel compound may be able to formed via a conventional injection molding process.

[0051] While the above description contains many specifics, these specifics should not be construed as limitations on the scope of the invention, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art may envision many other possible variations that are within the scope and spirit of the invention as defined by the claims appended hereto.