Weather strip

Abstract

A weather strip includes an ethylene-α-olefin-nonconjugated diene copolymer rubber composition having a volume resistivity of no less than 1.0E+6 Ω.Math.cm and having a specific gravity of less than 1.30, the rubber composition including: carbon black in an amount of 40 parts by mass to 140 parts by mass; and at least one polymer having a specific gravity of no more than 1.8 and an ethylene content of no more than 70 wt % and at least one polymer having a specific gravity of no more than 1.8 and an ethylene content of no less than 70 wt % in a collective amount of 5 parts by mass to 50 parts by mass, per 100 parts by mass of an EPDM polymer. At least a mount base of the weather strip, which is to be mounted to a car body, is formed of the rubber composition.

Claims

1. A weather strip, comprising: a mount base, which is to be mounted to a car body, wherein the mount base of the weather strip is formed of a rubber composition in a vulcanized state having a volume resistivity of no less than 1.0E+6 Ω.Math.cm and a specific gravity of less than 1.30, the rubber composition in an unvulcanized state including: ethylene-α-olefin-nonconjugated diene copolymer in an amount of 100 parts by mass; carbon black in an amount of 40 parts by mass to 140 parts by mass; and at least one first polymer having a specific gravity of no more than 1.8 and an ethylene content of no more than 70 wt % and at least one second polymer having a specific gravity of no more than 1.8 and an ethylene content of no less than 70 wt % in a collective amount of 5 parts by mass to 50 parts by mass, wherein the first polymer is an ethylene propylene rubber having no double bond derived from a nonconjugated diene, which is a cross-linking site, the ethylene propylene rubber is included in an amount of no less than 0.5 part by mass per 100 parts by mass of the ethylene-α-olefin-nonconjugated diene copolymer, the second polymer is an ethylene-α-olefin copolymer having no double bond derived from a nonconjugated diene, which is a cross-linking site, and the ethylene-α-olefin copolymer is included in an amount of no less than 0.5 part by mass per 100 parts by mass of the ethylene-α-olefin-nonconjugated diene copolymer.

2. The weather strip according to claim 1, wherein the ethylene-α-olefin copolymer is selected from the group consisting of ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-octene copolymer, ethylene-1-butene-1-hexene copolymer, ethylene-1-butene-4-methyl-1-pentene copolymer, and ethylene-1-butene-1-octene copolymer.

3. A composition for a weather strip, comprising: a rubber composition in a vulcanized state having a volume resistivity of no less than 1.0E+6 Ω.Math.cm and a specific gravity of less than 1.30, the rubber composition in an unvulcanized state including: ethylene-α-olefin-nonconjugated diene copolymer in an amount of 100 parts by mass; carbon black in an amount of 40 parts by mass to 140 parts by mass; and at least one first polymer having a specific gravity of no more than 1.8 and an ethylene content of no more than 70 wt % and at least one second polymer having a specific gravity of no more than 1.8 and an ethylene content of no less than 70 wt % in a collective amount of 5 parts by mass to 50 parts by mass, wherein the first polymer is an ethylene propylene rubber having no double bond derived from a nonconjugated diene, which is a cross-linking site, the ethylene propylene rubber is included in an amount of no less than 0.5 part by mass per 100 parts by mass of the ethylene-α-olefin-nonconjugated diene copolymer, the second polymer is an ethylene-α-olefin copolymer having no double bond derived from a nonconjugated diene, which is a cross-linking site, and the ethylene-α-olefin copolymer is included in an amount of no less than 0.5 part by mass per 100 parts by mass of the ethylene-α-olefin-nonconjugated diene copolymer.

4. The composition according to claim 3, wherein the ethylene-α-olefin copolymer is selected from the group consisting of ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-octene copolymer, ethylene-1-butene-1-hexene copolymer, ethylene-1-butene-4-methyl-1-pentene copolymer, and ethylene-1-butene-1-octene copolymer.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIGS. 1A and 1B are cross-sectional views of weather strips according to examples.

DETAILED DESCRIPTION

(2) Provided is a weather strip in which at least the mount base of the weather strip to a car body is formed of an ethylene-α-olefin-nonconjugated diene copolymer rubber composition having a volume resistivity of no less than 1.0E+6 Ω.Math.cm and having a specific gravity of less than 1.30, the rubber composition including carbon black in an amount of 40 parts by mass to 140 parts by mass and a polymer having an ethylene content of no more than 70 wt % and a polymer having an ethylene content of no less than 70 wt % in a collective amount of 5 parts by mass to 50 parts by mass per 100 parts by mass of an EPDM polymer.

EXAMPLES

(3) An example illustrated in FIG. 1A is a weather strip 1 to be mounted to a flange 12 that is a portion of a trunk opening periphery 11 of an automobile to which the weather-strip is to be fitted. An example illustrated in FIG. 1B is a weather strip 31 to be mounted to a channel portion 15 that is a portion of a roof of an automobile to which the weather trip is to be fitted.

(4) The formulations of EPDM rubber compositions of examples created to be used for the examples above and the formulations of EPDM rubber compositions of comparative examples are illustrated in Table 1, Table 2, and Table 3.

(5) TABLE-US-00001 TABLE 1 Comparative Comparative Raw Material Trade name Example 1 Example 2 Example 3 example 1-1 example 1-2 EPDM NORDEL IP 4570 100 100 100 100 100 Carbon Asahi #60UGS 95 95 95 95 95 Oil Diana Process 82 82 82 82 82 Oil PS-380 Calcium Whiton B 29.1 29.1 29.1 38.4 29.1 carbonate Kaolin CROWNCLAY 48.9 48.9 48.9 63.3 48.9 Polymer a EP11 10 20 30 15 40 Polymer b ENGAGE 8480 30 20 10 Zinc oxide META-Z 102 4 4 4 4 4 Stearic acid LUNAC S-50V 2.8 2.8 2.8 2.8 2.8 Formability PEG 4000S 1.1 1.1 1.1 1.1 1.1 enhancer Defoamer CML#31 5 5 5 5 5 Vulcanizing Powdery sulfur 1.7 1.7 1.7 1.7 1.7 agent Vulcanization *1 2.8 2.8 2.8 2.8 2.8 accelerator Material Volume resistivity 5.7E+06 6.1E+ 0 6 6.4E+06 1.3E+04 7.3E+06 Physical [Ω .Math. cm] Properties Specific gravity 1.19 1.19 1.19 1.25 1.19 Workability Tears of ◯ ◯ ◯ Δ X rubber strip Comparative Comparative Comparative Comparative Raw Material Trade name example 2-1 example 2-2 example 3 example 4 EPDM NORDEL IP 4570 100 100 100 100 Carbon Asahi #60UGS 95 95 158 95 Oil Diana Process 82 82 89 82 Oil PS-380 Calcium Whiton B 38.4 29.1 50 44 carbonate Kaolin CROWNCLAY 63.3 48.9 74 Polymer a EP11 Polymer b ENGAGE 8480 15 40 Zinc oxide META-Z 102 4 4 4 4 Stearic acid LUNAC S-50V 2.8 2.8 2.8 2.8 Formability PEG 4000S 1.1 1.1 1.1 1.1 enhancer Defoamer CML#31 5 5 4 5 Vulcanizing Powdery sulfur 1.7 1.7 1.7 1.7 agent Vulcanization *1 2.8 2.8 2.8 2.8 accelerator Material Volume resistivity 2.4E+06 5.0E+0 6 3.2E+04 1.0E+06 Physical [Ω .Math. cm] Properties Specific gravity 1.25 1.19 1.25 1.30 Workability Tears of X X ◯ ◯ rubber strip *1: Vulcanization accelerator: a mixture of “RHENOCURE NPV/C”, “NOCCELER BZ”, “NOCCELER M” and “NOCCELER TT”

(6) TABLE-US-00002 TABLE 2 Raw Material Trade name Example 4 Example 5 Example 6 Example 7 Example 8 EPDM NORDEL IP 4570 100 100 100 100 100 Carbon Asahi #60UGS 95 95 95 95 95 Oil Diana Process 82 82 82 82 82 Oil PS-380 Calcium Whiton B 29.1 29.1 29.1 29.1 29.1 carbonate Kaolin CROWNCLAY 48.9 48.9 48.9 48.9 48.9 Polymer a EP11 10 20 30 35 38 Polymer b ENGAGE 8480 30 20 10 5 2 Zinc oxide META-Z 102 6 6 6 6 6 Stearic acid LUNAC S-50V 2.8 2.8 2.8 2.8 2.8 Formability PEG 4000S 1.1 1.1 1.1 1.1 1.1 enhancer Defoamer CML#31 9 9 9 9 9 Vulcanizing Powdery sulfur 1.7 1.7 1.7 1.7 1.7 agent Vulcanization *1 2.8 2.8 2.8 2.8 2.8 accelerator Material Volume resistivity 7.5E+06 6.1E+ 0 6 6.4E+06 6.6E+06 6.6E+06 Physical [Ω .Math. cm] Properties Specific gravity 1.20 1.20 1.20 1.20 1.20 Workability Tears of ◯ ◯ ◯ ◯ ◯ rubber strip Comparative Comparative Comparative Raw Material Trade name example 5 example 6 example 7 EPDM NORDEL IP 4570 100 100 100 Carbon Asahi #60UGS 95 95 95 Oil Diana Process 82 82 82 Oil PS-380 Calcium Whiton B 29.1 29.1 44 carbonate Kaolin CROWNCLAY 48.9 48.9 74 Polymer a EP11 40 Polymer b ENGAGE 8480 40 Zinc oxide META-Z 102 6 6 6 Stearic acid LUNAC S-50V 2.8 2.8 2.8 Formability PEG 4000S 1.1 1.1 1.1 enhancer Defoamer CML#31 9 9 9 Vulcanizing Powdery sulfur 1.7 1.7 1.7 agent Vulcanization *1 2.8 2.8 2.8 accelerator Material Volume resistivity 5.0E+0 6 5.7E+06 1.0E+06 Physical [Ω .Math. cm] Properties Specific gravity 1.20 1.20 1.32 Workability Tears of X X ◯ rubber strip *1: Vulcanization accelerator: a mixture of “RHENOCURE NPV/C”, “NOCCELER BZ”, “NOCCELER M” and “NOCCELER TT”

(7) TABLE-US-00003 TABLE 3 Comparative Comparative Raw Material Trade name Example 9 Example 10 Example 11 Example 12 example 8 example 9 EPDM NORDEL IP 4570 100 100 100 100 100 100 Carbon Asahi #60UGS 95 95 95 95 95 95 Oil Diana Process 72 72 72 72 72 72 Oil PS-380 Calcium Whiton B 34.6 33.1 39.1 44.3 34.6 34.6 carbonate Kaolin CROWNCLAY 58.4 58.4 65.9 74.7 58.4 58.4 Polymer a EP11 20 22 10 5 40 Polymer b ENGAGE 8480 20 22 10 5 40 Zinc oxide META-Z 102 4 4 4 4 4 4 Stearic acid LUNAC S-50V 2.8 2.8 2.8 2.8 2.8 2.8 Formability PEG 4000S 1.1 1.1 1.1 1.1 1.1 1.1 enhancer Defoamer CML#31 5 5 5 5 5 5 Vulcanizing Powdery sulfur 1.7 1.7 1.7 1.7 1.7 1.7 agent Vulcanization *1 2.8 2.8 2.8 2.8 2.8 2.8 accelerator Material Volume resistivity 5.8E+06 7.2E+06 4.5E+06 2.3E+06 5.2E+0 6 5.6E+06 Physical [Ω .Math. cm] Properties Specific gravity 1.21 1.20 1.26 1.29 1.21 1.21 Workability Tears of ◯ ◯ ◯ ◯ X X rubber strip *1: Vulcanization accelerator: a mixture of “RHENOCURE NPV/C”, “NOCCELER BZ”, “NOCCELER M” and “NOCCELER TT”

(8) The following products were used for the materials illustrated in Table 1, Table 2, and Table 3. The EPDM: “NORDEL IP 4570”, trade name of Dow Chemical Japan Ltd. The carbon black: “Asahi #60”, trade name, of Asahi Carbon Co., Ltd. The plasticizer: “Diana Process Oil PS-380”, trade name, of Idemitsu Kosan Co., Ltd. The calcium carbonate: “Whiton B” (specific gravity of 2.7), trade name, of Bihoku Funka Kogyo Co., Ltd. The kaolin clay serving as white, functional filler: “CROWNCLAY”, trade name, of Active Minerals International LLC. Polymer a: “JSR EP11” (ethylene content of 52 wt %, specific gravity of 0.86), trade name of an ethylene propylene rubber product of JSR Corporation. Polymer b: “ENGAGE 8480” (ethylene content of 77 wt %, specific gravity of 0.904), trade name of a polyolefin elastomer product of Dow Chemical Japan Ltd. The zinc oxide: “META-Z 102”, trade name, of Inoue Calcium Corporation. The stearic acid: “LUNAC S-50V”, trade name, of Kao Corporation. The formability enhancer: “PEG 4000S”, trade name, of Sanyo Chemical Industries, Ltd. The defoamer: “CML#31”, trade name, of Ohmi Chemical Industry Co., Ltd. The powdery sulfur serving as a vulcanizing agent: “fine sulfur powder 325 mesh”, trade name, of Hosoi Chemical Industry Co., Ltd. The vulcanization accelerator: a mixture of “RHENOCURE NPV/C”, trade name, of Rhein Chemie Japan Ltd., and “NOCCELER BZ”, “NOCCELER M”, and “NOCCELER TT”, trade names, of Ouchi Shinko Chemical Industrial Co., Ltd.

(9) In examples 1 to 3, different formulation ratios of polymer a and polymer b were used.

(10) In examples 4 to 6, the amounts of zinc oxide and defoamer were increased compared to those in examples 1 to 3.

(11) In examples 7 and 8, a different formulation ratio of polymer a and polymer b was used from that in example 6.

(12) In example 9, the amount of plasticizer (oil) was reduced and the amounts of calcium carbonate and kaolin clay were increased compared to those in example 2.

(13) In examples 10 to 12, a different formulation ratio of polymer a and polymer b was used from that in example 9.

(14) The EPDM rubber compositions of examples and comparative examples were kneaded by a kneader and then subjected to vulcanizing process at 170° C. for ten minutes, and specimens were thus created. The volume resistivity and the specific gravity of the specimens were measured in accordance with JIS K 6911 and JIS K 6268, respectively. The rubber compositions formed into a strip shape were examined to determine whether the rubber strips had tears after the sheeting/stripping process (open-roll) and the cooling process (batch-off) in the rubber kneading process. A rubber strip with no tear after the sheeting/stripping process and the cooling process was rated “good (◯)”. When the rubber strip was torn in one of the sheeting/stripping process and cooling process, it was rated “fair (Δ)”. When the rubber strip was torn in both the sheeting/stripping process and the cooling process, it was rated “poor (x)”. The results are shown in Table 1, Table 2, and Table 3.

(15) The rubber compositions of examples 1 to 12 had a volume resistivity of no less than 1.0E+6 Ω.Math.cm and a specific gravity of less than 1.30, and were all rated good in terms of tears of the strip.

(16) The rubber compositions of comparative examples 1-1, 1-2, 2-1, 2-2, 5, 6, 8, and 9 were torn because the rubber compositions included a single species of polymer.

(17) The rubber composition of comparative example 3 had a volume resistivity of 3.2E+4 Ω.Math.cm. This is believed to be due to a lack of kaolin clay, polymer a, and polymer b.

(18) The rubber composition of comparative example 4 had a specific gravity of 1.30, and the rubber composition of comparative example 7 had a specific gravity of 1.32. These relatively high specific gravities are believed to be due to an increased amount of kaolin clay.

(19) The weather strips illustrated in FIGS. 1A and 1B were manufactured with the rubber compositions of examples 1 to 12.

(20) The weather strip 1 illustrated in FIG. 1A that is to be mounted to a trunk opening has a trimmed portion 2 that is a mount base having a substantially c-shaped cross section and is to be mounted to the flange 12 made of a steel plate or an aluminum alloy plate, a hollow sealing portion 3 that has a hollow shape and is to be in contact with a trunk lid 13 for sealing the gap therebetween, and sealing lips 4 that are to be in contact with a trunk opening periphery surface 11 for sealing the gap therebetween. In the trimmed portion 2, a vehicle outer side wall, a vehicle inner side wall, and a bottom wall form the substantially c-shaped cross section. Flange retaining lips 21 project from the inner surfaces of the vehicle outer side wall and the vehicle inner side wall. Inside the trimmed portion 2, an insert 22 made of a sheet metal or resin is embedded for reinforcement. The sealing lips 4 project from the outer surfaces of the vehicle outer side wall and the vehicle inner side wall.

(21) The trimmed portion 2 and the flange retaining lips 21 (hatched area) are formed of an EPDM rubber composition of examples 1 to 12, and the hollow sealing portion 3 and the sealing lips 4 are formed of a sponge rubber composition. The EPDM rubber composition and the sponge rubber composition are co-extruded to form the weather strip 1.

(22) Pushing the trimmed portion 2 downward onto the flange 12 to insert the flange 12 into the inner portion having the substantially c-shaped cross section causes the flange retaining lips 21 to retain the flange 12, and thus the weather strip 1 can be mounted to the flange 12. The trimmed portion 2 and the flange retaining lips 21, both to be in contact with the flange 12, are formed of a highly electrically resistive EPDM rubber composition and thus galvanic corrosion of the flange 12 can be prevented, and a light weather strip 1 can be obtained.

(23) The weather strip 31 illustrated in FIG. 1B that is to be mounted to a roof has a mount base 32 having a substantially plate-like shape and inserted and held in the channel portion 15 made of a steel plate or an aluminum alloy plate, and a hollow sealing portion 33 that is to be in contact with a periphery protector 17 of a sunroof glass 16 for sealing the gap therebetween.

(24) The mount base 32 and a portion of the hollow sealing portion 33 (hatched area) are formed of an EPDM rubber composition of examples 1 to 12, and the rest of the portions of the hollow sealing portion 33 are formed of a sponge rubber composition. The EPDM rubber composition and the sponge rubber composition are co-extruded to form the weather strip 31.

(25) In this example, the mount base 32 and a portion of the hollow sealing portion 33, both to be in contact with the channel portion 15, are formed of a highly electrically resistive EPDM rubber composition and thus galvanic corrosion of the channel portion 15 can be prevented, and a light weather strip 31 can be obtained.

(26) The present invention is not limited to the examples described above, and may be modified as appropriate and embodied without departing from the scope of the present invention.