THERMOPLASTIC ELASTOMER COMPOUNDS HAVING HIGH BIORENEWABLE CONTENT FOR OVERMOLDING ON NON-ELASTOMERIC POLYMER SUBSTRATES

Abstract

TPE compounds having at least 35 weight percent of bio-renewable content are disclosed as candidates for use as overmolding layers on to polypropylene substrates.

Claims

1. A thermoplastic elastomer compound, comprising: (a) HSFC (b) bio-PE (c) SEBS (d) PP (e) mineral oil, wherein the compound has a bio-renewable content of at least 35 weight percent and a 90 Peel Test on PP of greater than 10 pli.

2. The compound of claim 1, wherein the HSFC is bio-renewable content from sources comprising sugar cane or corn and wherein the bio-PE is bio-renewable content from sources comprising sugar cane.

3. The compound of claim 1, wherein the compound further optional additives selected from the group consisting of adhesion promoters; biocides; anti-fogging agents; anti-static agents; dispersants; fillers and extenders; fire and flame retardants and smoke suppressants; hardness adjusters; initiators; lubricants; micas; mold release agents; colorants; plasticizers; processing aids; release agents; silanes, titanates; zirconates; slip agents; anti-blocking agents; stabilizers; stearates; ultraviolet light absorbers; viscosity regulators; waxes; and combinations of them.

4. The compound of claim 3, wherein the optional additives comprise UV absorbers, anti-oxidants, mold release agents, or combinations thereof.

5. The compound of claim 3, wherein the weight percent ranges of ingredients are TABLE-US-00005 HSFC TPE 30-80 Bio-based PE 1-30 SEBS 3-40 PP 1-30 Mineral Oil 3-60 Optional Additives 0.05-2.

6. The compound of claim 4, wherein the weight percent ranges of ingredients are TABLE-US-00006 HSFC TPE 40-60 Bio-based PE 5-20 SEBS 5-20 PP 5-20 Mineral Oil 10-30 Optional Additives 0.1-1.

7. The compound of claim 3, wherein the weight percent ranges of ingredients are TABLE-US-00007 HSFC TPE 42-48 Bio-based PE 7-17 SEBS 10-15 PP 7.5-9.sup. Mineral Oil 16-22 Optional Additives 0.6-1.0.

8. The compound of claim 4, wherein the weight percent ranges of ingredients are TABLE-US-00008 HSFC TPE 42-48 Bio-based PE 7-17 SEBS 10-15 PP 7.5-9.sup. Mineral Oil 16-22 Optional Additives 0.6-1.0.

9. The compound of claim 1, wherein the Shore A Hardness is less than 65, wherein the percent Elongation is less than 100, and wherein the 90 Peel Test on PP is at least about 15.

10. A polymeric article, comprising a compound of claim 1.

11. The polymeric article of claim 10, wherein the article is in final molded, extruded, thermoformed, calendered, spun, casted, or 3D-printed shape.

12. The polymeric article of claim 10, wherein the compound is an overmolding layer and where the polymeric article also comprises a thermoplastic overmolded layer, wherein the overmolding layer is two-component molded onto the overmolded layer.

13. The polymeric article of claim 12, one overmolding layer of the compound is one formulation and wherein a second overmolding layer of the compound is a second formulation and wherein both overmolding layers are two-component molded to the overmolded layer.

14. The polymeric article of claim 12, wherein each overmolding layer provides a gripping surface for a human hand.

15. A method of using the compound of claim 1 to form a polymer article, wherein the method comprises the step of shaping the compound to form the article, wherein shaping is selected from the group consisting of molding, extrusion, thermoforming, calendering, spinning, casting, or 3D-printing.

Description

EXAMPLES

[0056] Table 3 shows the commercial source of the ingredients for all Examples 1-5, their formulations, the processing of the formulations to make extruded pellets and then to mold into sample plaques for testing. Table 4 shows the results of that testing.

[0057] Overmolding Test Preparation

[0058] For the overmolding test, the following preparations were made:

[0059] Formolene 1102KR, a 4 MFR homopolymer polypropylene from Formosa Plastics, was used to mold the polypropylene substrate. This PP is representative of a frequently used homopolymer polypropylene substrate.

[0060] A Milacron injection molding machine was used to prepare the PP substrate and prepare plaques for the measurements of adhesion.

[0061] Plaques for the measurement of adhesion were prepared by injection molding TPE materials onto cold inserted rigid Formolene 1102KR 4 MFR polypropylene substrates. The barrel temperature of the injection molding machine was set from 180 C. to 215 C. (360 F. to 420 F.) and the injection velocity from 15 mm/sec to 65 mm/sec. The condition for molding the PP substrate was barrel temperature from 190 C. to 230 C. (375 F. to 445 F.) and the injection velocity from 15 mm/sec to 65 mm/sec.

[0062] Procedure for the 90 Peel Test on PP

[0063] The adhesion between the TPE overmolding layer and the rigid thermoplastics substrate of 4 MFR homopolymer polypropylene was measured by a 90 degree peel test which is a modified ASTM D903 method.

[0064] This test is done on overmolded plaques with the TPE overmolding layer on top of the 4 MFR homopolymer polypropylene overmolded substrate.

[0065] A TPE strip 2.54 cm (1 inch) wide and 10.16 cm (4 inches) long was cut, and a 7.62 cm (3 inches) portion of the strip was adhered to the polypropylene substrate in an overmolded position. The remaining 2.54 cm (1 inch) portion of the strip not adhered was pulled at a 900 angle from the substrate using an Instron tensile tester operating at 10/min (15.24 cm/min) as the pulling speed.

[0066] The substrate had been locked in its place on wheels in order to maintain the 90 angle of peel as the elastomer was being pulled. The adhesion strength, matching the peel strength, is measured by the force required to pull the elastomer strip orthogonally from the substrate to which the strip is adhered. The test result was reported as a maximum strength over 5.08 cm (2 inches) of delamination due to the pulling force. The adhesion was also categorized based on a visual observation of the failure mode, i.e., an adhesive failure if no TPE residue is left on the substrate or a cohesive failure if the failure is in TPE.

[0067] Two samples for each Example were tested, and the results averaged. The numerical results are expressed in pound-force per inch (lb.sub.f/in) units, wherein each pound-force per inch equals 0.175127 Newtons per millimeter (N/mm).

TABLE-US-00003 TABLE 3 Example Ingredients (Wt. %) 1 2 3 4 5 SF 903 Polystyrene-polyhydrogenated farnesene-polystyrene triblock 43.54 47.69 46.88 47.69 46.40 copolymer bio-based elastomers (Kuraray) G1654 Polystyrene-polyethylene butylene-polystyrene copolymer 13.06 14.31 10.49 14.31 elastomer (Kraton) G1642 Polystyrene-polyethylene butylene-polystyrene copolymer 15.80 elastomer (Kraton) Puretol PSO 380 Mineral Oil plasticizer (Petro Canada) 19.16 21.94 16.09 21.30 Puretol 10 Mineral Oil plasticizer (Petro Canada) 21.94 SPB 608 Polyethylene bio-based polymer (Braskem) 13.06 7.63 17.49 7.63 9.30 Profax PD 702 Polypropylene (Lyondell Basell) 10.45 7.63 8.40 7.63 6.50 Irgafax 168 Tris(2,4-ditert-butylphenyl)phosphite antioxidant (BASF) 0.13 0.14 0.11 0.14 0.14 Irganox 1010 Pentaerythritol Tetrakis(3-(3.5-di-tert-butyl-4- 0.08 0.09 0.06 0.09 0.08 hydroxyphenyl)propionate) antioxidant (BASF) Kemamide E Ultra erucamide (PMC Biogenix) 0.09 0.10 0.09 0.10 0.09 Tinuvin 328 2-(2H-benzotriazol-2-yl)-4.6-ditertpentylphenol UV 0.22 0.24 0.17 0.24 0.23 absorber (BASF) UV 62 Butanedioic acid, dimethyl ester, polymer with 4-hydroxy- 0.22 0.24 0.21 0.24 0.23 2,2,6,6-tetramethyl-1-piperidine-ethanol UV stabilizer (BASF) TOTAL 100 100 100 100 100 Mixing Equipment Twin Screw extruder Mixing Temp. 160 C. Mixing Speed 500 ppm Order of Addition of Ingredients All together Form of Product After Mixing Pellets

TABLE-US-00004 TABLE 4 Properties and Performance Results 1 2 3 4 5 Unacceptable Shore A Hardness (ASTM D2240, 10 s delay) 55 44 56 45 39 >65 Specific gravity (ASTM D792) 0.90 0.91 0.90 0.89 0.89 Tensile Strength, psi (ASTM D412, Die C) 600 437 592 401 430 Elongation, % (ASTM D412, Die C) 288 192 305 177 209 <100 Viscosity @ 1340.5/sec and 200 C. (ASTM D3835) 73 79 73 66 72 Overmolding Max 90 peel on PP (pli) 19 18 18 18 15 <10 Failure Mode: (A = adhesive) (C = cohesive) A A A A A Calculated bio renewable content (%) 43 41 50 41 41 <35

[0068] All five Examples were successfully formulated and prepared to serve as overmolding layers on to a polypropylene substrate. As test results indicated, the 90 peel adhesion was well in excess of 10 pli (1.75127 Newtons per millimeter (N/mm)).

[0069] The 90 Peel Test on PP can be greater than about 12, desirably at least 15, and can range from about 16 to about 20 and preferably from about 18 to about 19.

[0070] The percent Elongation can range from about 170 to about 310 and preferably from about 200 to about 300.

[0071] The Shore A Hardness can range from about 40 to about 60 and preferably from about 45 to about 55.

[0072] For those markets seeking to have bio-renewal content in overmolding thermoplastic elastomers laminated to overmolded non-elastomeric thermoplastic polymers, the percent bio-renewable content can range from about 40 to about 50 and preferably from about 41 to about 45.

[0073] The invention is not limited to the above embodiments. The claims follow.