EP(D)M-EVM WIPER RUBBER WITH IMPROVED COLD FLEXIBILITY

Abstract

A wiper rubber (10) for a wiper blade, especially for a windshield wiper, with an elastomer material comprising a polymer blend composed of at least one ethylene-propylene-diene rubber and/or at least one ethylene-propylene rubber, and at least one ethylene-vinyl acetate copolymer is disclosed. In order to provide a wiper rubber that has improved wiping quality and improved running properties, especially reduced or zero running noise, such as humming, whistling, squeaking, smacking, turnover noises, et cetera, both at moderate and especially at cold outside temperature, and especially also over a broad frequency range customary in wiper operation, the at least one ethylene-vinyl acetate copolymer, based on the total weight of the at least one ethylene-vinyl acetate copolymer, comprises a vinyl acetate content within a range from 40% by weight to 90% by weight, where the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 0.1% by weight to 30% by weight of the at least one ethylene-vinyl acetate copolymer.

Claims

1. A wiper rubber (10) for a wiper blade, the wiper rubber comprising an elastomer material comprising a polymer blend composed of at least one ethylene-propylene-diene rubber and/or at least one ethylene-propylene rubber, and at least one ethylene-vinyl acetate copolymer, wherein the at least one ethylene-vinyl acetate copolymer, based on the total weight of the at least one ethylene-vinyl acetate copolymer, comprises a vinyl acetate content within a range from 40% by weight to 90% by weight, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 0.1% by weight to <30% by weight of the at least one ethylene-vinyl acetate copolymer.

2. The wiper rubber (10) according to claim 1, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 2% by weight to 20% by weight of the at least one ethylene-vinyl acetate copolymer.

3. The wiper rubber (10) according to claim 1, wherein the at least one ethylene-vinyl acetate copolymer, based on the total weight of the at least one ethylene-vinyl acetate copolymer, comprises a vinyl acetate content within a range from 50% by weight to 90% by weight.

4. The wiper rubber (10) according to claim 1, wherein the at least one ethylene-vinyl acetate copolymer, based on the total weight of the at least one ethylene-vinyl acetate copolymer, comprises a vinyl acetate content within a range from 65% by weight to 90% by weight.

5. The wiper rubber (10) according to claim 1, wherein the polymer blend further comprises at least one further rubber.

6. The wiper rubber (10) according to claim 5, wherein the at least one further rubber comprises or is natural rubber and/or butadiene rubber and/or styrene-butadiene rubber and/or isoprene rubber.

7. The wiper rubber (10) according to claim 5, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 2% by weight to 60% by weight of the at least one further rubber.

8. The wiper rubber (10) according to claim 1, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 10% by weight to 99.9% by weight of the at least one ethylene-propylene-diene rubber and/or ethylene-propylene rubber.

9. The wiper rubber (10) according to claim 1, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 40% by weight to 80% by weight of the at least one ethylene-propylene-diene rubber and/or ethylene-propylene rubber.

10. The wiper rubber (10) according to claim 1, wherein the elastomer material further comprises at least one filler and/or at least one silane and/or at least one plasticizer and/or at least one oil and/or at least one vulcanizing agent and/or at least one vulcanizing auxiliary and/or at least one antioxidant and/or at least one processing auxiliary.

11. The wiper rubber (10) according to claim 1, wherein the wiper rubber (10) has a wiper (11) and a securing section (14), wherein the securing section (14, 13) and/or the wiper lip (11) is formed from the elastomer material.

12. A wiper blade, especially for a windshield wiper, comprising a wiper rubber (10) according to claim 1.

13. The wiper rubber (10) according to claim 1, wherein the wiper rubber is configured for use with a windshield wiper.

14. The wiper rubber (10) according to claim 1, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 2% by weight to 15% by weight of the at least one ethylene-vinyl acetate copolymer.

15. The wiper rubber (10) according to claim 1, wherein the at least one ethylene-vinyl acetate copolymer, based on the total weight of the at least one ethylene-vinyl acetate copolymer, comprises a vinyl acetate content within a range from 60% by weight to 90% by weight.

16. The wiper rubber (10) according to claim 1, wherein the at least one ethylene-vinyl acetate copolymer, based on the total weight of the at least one ethylene-vinyl acetate copolymer, comprises a vinyl acetate content within a range from 70% by weight to 80% by weight.

17. The wiper rubber (10) according to claim 5, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 15% by weight to 40% by weight of the at least one further rubber.

18. The wiper rubber (10) according to claim 1, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 20% by weight to 95% by weight of the at least one ethylene-propylene-diene rubber and/or ethylene-propylene rubber.

19. The wiper rubber (10) according to claim 1, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 30% by weight to 95% by weight, of the at least one ethylene-propylene-diene rubber and/or ethylene-propylene rubber in total.

20. The wiper rubber (10) according to claim 1, wherein the polymer blend, based on the total weight of the polymers in the polymer blend, comprises 40% by weight to 80% by weight of the at least one ethylene-propylene-diene rubber and/or ethylene-propylene rubber in total.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Further advantages and advantageous configurations of the subject matter of the invention are illustrated by the drawing and the working example and elucidated in the description which follows. It should be noted here that the drawing and the working example are merely of descriptive character and are not intended to limit the invention in any way at all. The drawing shows:

[0039] FIG. 1 shows a side view of a wiper blade according to the invention

[0040] FIG. 2 shows a schematic cross section, along line II-II in FIG. 1, showing only a wiper rubber of the invention.

DETAILED DESCRIPTION

[0041] FIG. 1 shows a wiper blade 100 comprising a wiper rubber 10 and a spoiler 32. End caps 58 which limit the relative movability of the wiper rubber 10 and the spoiler 32 relative to one another in the longitudinal direction, are located at the ends of the wiper blade 10. A connecting element 11 is fastened to the wiper blade 100 in the central region of the wiper blade 100. The connecting element 11 serves for articulated connection to a wiper arm (not illustrated). The illustrated wiper blade 100 is only an example of a type of wiper blade that can be used in connection with the wiper rubber 10 of the invention.

[0042] FIG. 2 shows an embodiment of the wiper rubber 10 of the invention. The wiper rubber 10 is configured for use with a wiper blade, for example for windshield wipers, such as shown in FIG. 1. The wiper rubber 10 comprises an elastomer material based on a polymer blend composed of at least one ethylene-propylene-diene rubber and/or at least one ethylene-propylene rubber, and at least one ethylene-vinyl acetate copolymer. This at least one ethylene-vinyl acetate copolymer, based on the total weight of the at least one ethylene-vinyl acetate copolymer, includes a vinyl acetate content within a range from 0% by weight to 90% by weight. The polymer blend here comprises, based on the total weight of the polymers in the polymer blend, 0.1% by weight to <30% by weight, by way of example 2% by weight to 20% by weight, of the at least one ethylene-vinyl acetate copolymer.

[0043] FIG. 2 shows that the wiper rubber 10 has a wiper lip 11 with a wiper lip tip 11a. and with a wiper lip wedge 11b, and also a tilting element 12 and a securing section 14 with brush strips 13. The wiper lip 11, especially the wiper lip wedge lib of the wiper lip 11, is connected here via the tilting element 12 to the brush strips 13 of the securing section 14. The securing section 14 is designed here for mounting of the wiper rubber 10 in a wiper blade rail and is in the form of a hollow profile.

[0044] The wiper rubber 10 here may, for example, have been formed partly or entirely from the elastomer material. For example, the wiper lip 11, for example the wiper lip tip 11a and/or the wiper lip wedge 11b of the wiper lip 11, and/or the tilting element 12 and/or the brush strips 13 and/or the securing section 14 may have been formed from the elastomer material.

Working Examples

[0045] Working example series 1: Wiper rubbers made of EP(D)M-EVM polymer blends with a small amount of an EVM with a high vinyl acetate content

[0046] A series of wiper rubbers based on a series of polymer blends was extruded and vulcanized, which comprised, based on the total weight of the polymers in the polymer blend, 70% by weight to 99.9% by weight of ethylene-propylene-diene rubber and/or ethylene-propylene rubber (EP(D)M) and 0.1% by weight to <30% by weight of ethylene-vinyl acetate copolymer (EVM) with a vinyl acetate content based on the total weight of the at least one ethylene-vinyl acetate copolymer within a range from 40% by weight to 90% by weight.

[0047] Working example series 2: Wiper rubbers made of EP(D)M-EVM-NR/BR/SBR/IR polymer blends with a small amount of an EVM with a high vinyl acetate content

[0048] A series of wiper rubbers based on a series of polymer blends was extruded and vulcanized, which comprised, based on the total weight of the polymers in the polymer blend, 40% by weight to 180% by weight of ethylene-propylene-diene rubber and/or ethylene-propylene rubber (EP(D)M), 0.1% by weight to <30% by weight of ethylene-vinyl acetate copolymer (EVM) with a vinyl acetate content based on the total weight of the at least one ethylene-vinyl acetate copolymer within a range from 40% by weight to 90% by weight and 2% by weight to 60% by weight of at least one further rubber, for example natural rubber and/or butadiene rubber and/or styrene-butadiene rubber and/or isoprene rubber. It was possible here to extrude the wiper rubbers in the form of hollow profiles.

[0049] The damping properties and cold flexibility of the wiper rubbers according to working example series 1 and 2 were measured by means of dynamic-mechanical analysis at different temperatures and frequencies.

[0050] The measurements showed that, by adding just a small amount of ethylene-vinyl acetate copolymer having a high vinyl acetate content and/or natural rubber/butadiene rubber/styrene-butadiene rubber/isoprene rubber, it was advantageously possible, in the dynamic-mechanical analysis within a frequency range from 0.001 Hz to 300 Hz, to achieve a tangent delta value representative of the damping properties of more than 0.20, especially of 0.24, for example of 0.25, in some cases even of 0.30. It was thus possible to at least maintain or especially even improve the tangent delta value and hence the damping properties compared to ethylene-propylene(-diene) rubber (EP(D)M) having a tangent delta value at 300 Hz of about 0.20 or less.

[0051] When the tangent delta values were plotted against frequency and/or temperature, there was advantageously barely any shift or no shift in a main peak representative of the cold flexibility and or glass transition temperature to higher temperatures and/or to lower frequencies, especially by contrast with polymer blends composed of ethylene-propylene(-diene) rubber (EP(D)M) and 30% by weight to 60% by weight of ethylene-vinyl acetate copolymer (EVM) with a vinyl acetate content based on the total weight of ethylene-vinyl acetate copolymer within a range from 45% by weight to 85% by weight.

[0052] It was thus possible through the addition of just a small amount of ethylene-vinyl acetate copolymer having a high vinyl acetate content, especially also in the presence of at least one further polymer, for example at least one further rubber, such as natural rubber and/or butadiene rubber and/or styrene-butadiene rubber and/or isoprene rubber, to at least sufficiently reduce or even prevent unwanted running noise, such as humming, whistling, squeaking, smacking, turnover noises, et cetera, over a broad temperature range including both moderate and cold outside temperatures, and, for example, also over a broad frequency range including frequencies customary in wiper operation.