Chemistry of hydrocarbon compounds – Product blend – e.g. – composition – etc. – or blending process... – Component of indefinite molecular weight greater than 150
Reexamination Certificate
2000-06-27
2002-05-07
McAvoy, Ellen M. (Department: 1764)
Chemistry of hydrocarbon compounds
Product blend, e.g., composition, etc., or blending process...
Component of indefinite molecular weight greater than 150
C585S012000, C521S140000, C521S144000
Reexamination Certificate
active
06384290
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to oil-extended copolymers for sponge. More precisely, the present invention relates to oil-extended copolymers which can provide sponge rubbers excellent in various properties including long-term compression set properties, sealing properties, low-temperature properties, processabilities, external appearance and so on.
2. Description of Related Art
Ethylene-&agr;-olefin nonconjugated diene copolymer rubbers having superior properties in heat resistance, weathering resistance, processabilities and cost performance have been used in most of sponge rubbers for automobile and construction use. Particularly, they are widely used as materials essential for door seals, trunk seals and window seals of automobiles. Since door seal sponges are used in a compressed state for a long time as sealing materials sandwiched between a door and a body when door is closed, they are preferably less deformed by compression. In other words, seal sponges with a small compression set have been demanded. In addition, it is important that opening and closing of door can be smoothly carried out over a broad range of temperature from a high temperature to a low temperature. Therefore, it is necessary that sponge rubbers also maintain a sufficient softness over a wide range of temperature. In addition to the above described properties necessary for sponge rubbers, it is demanded that they are sufficiently good in processabilities such as kneading property, extruding property, shape retention property and the like. For example, JP-A-3-20339 discloses a use of an ethylene-&agr;-olefin nonconjugated diene copolymer, having a weight ratio of ethylene/&agr;-olefin of 73/27 to 40/60, having an iodine value which represents a non-conjugated diene content of 10 to 36 and having a Mooney viscosity (ML 1+4 (121° C.)) of 135 to 200. Said copolymer, however, does not satisfy a compression set satisfying the current demands.
While the compression set can be improved when Mooney viscosity (ML 1+4 (121° C.)), an indicator for the molecular weight, exceeds 200, the kneading property is deteriorated and carbon aggregation masses are formed. In addition, surface roughening and edge damage may be occurred. Therefore, it is difficult to use copolymers having such a high Mooney viscosity practically.
While JP-A-3-20339 describes use of copolymers having a Mooney viscosity (ML 1+4 (121° C.)) of 165 and 210 as measured without using an extender oil, copolymers having a Mooney viscosity higher than 200 are not well satisfied kneading property.
Under these circumstances, the present inventors have extensively studied for copolymers having no problems described above, as the result, and have found that copolymers obtained by extending a copolymer having a high Mooney viscosity with an extender oil can provide sponge rubbers excellent in various properties including long-term compression set properties, sealing properties, low-temperature properties, processabilities, external appearance and so on. The inventors have completed the present invention.
SUMMARY OF THE INVENTION
The present invention provides an oil-extended copolymer for sponge comprising an ethylene-&agr;-olefin nonconjugated diene copolymer satisfying the following conditions (1) to (4), and an extender oil in an amount of 10 to 90 parts by weight based on 100 parts by weight of said copolymer.
(1) a weight ratio of ethylene/&agr;-olefin of 73/27 to 40/60,
(2) an iodine value of 20 to 36 which represents a non-conjugated diene content,
(3) a Mooney viscosity (ML 1+4 (121° C.) in Mooney viscosity according to JIS-K-6300) of 100 to 180 as measured for a mixture formed by compounding 20 parts by weight of an extender oil based on 100 parts by weight of said copolymer, and
(4) a Q-value (a weight average of molecular chain
umber average of molecular chain) of 3 to 5 as measured by gel-permeation chromatography (GPC) of said copolymer.
DETAILED DESCRIPTION OF THE INVENTION
The oil-extended copolymer for sponge to be used in the present invention is an ethylene-&agr;-olefin nonconjugated diene copolymer (hereinafter, referred to as “copolymer”) satisfying the above-mentioned conditions (1) to (4).
Said copolymer is preferably a copolymer having a Mooney viscosity exceeding 200 as measured without adding an extender oil.
The &agr;-olefin includes, for example, propylene 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene and the like. Among them, propylene and 1-butene are preferred.
The weight ratio of ethylene/&agr;-olefin in the copolymer is 73/27 to 40/60, and preferably 67/33 to 45/55. When the proportion of ethylene is too large, the compression set of the sponge rubber at a lower temperature becomes extremely worse, the recovery property of the sponge rubber becomes remarkably poor and the rubber becomes improper as a sealing material. In contrast, when the proportion of ethylene is too small, the dispersion of reinforcing material such as carbon black, inorganic fillers and the like becomes insufficient, which results in causing surface roughening of the sponge rubber.
The nonconjugated diene includes, for example, linear nonconjugated dienes such as 1,4-hexadiene, 1,6-odtadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene and the like; cyclic nonconjugated dienes such as cyclohexadiene, dicyclopentadiene, methyltetraindene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene; trienes such as 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, 1,3,7-octatriene, 1,4,9-decatriene and the like. One of them can be used independently and two or more can be used in combination thereof. Preferred examples are 5-ethylidene-2-norbornene, dicyclopentadiene, or 5-ethylidene-2-norbornene and dicyclopentadiene. It is also possible to use a polyene, in place of the above-mentioned nonconjugated diene, such as 5-vinyl-2-norbornene, 5-(2-propenyl)-2-norbornene, 5-(3-butenyl)-2-norbornene, 5-(4-pentenyl)-2-norbornene, 5-(5-hexenyl)-2-norbornene, 5-(5-heptenyl)-2-norbornene, 5-(7-octenyl)-2-norbornene, 5-methylene-2-norbornene, 6,10-dimethyl-1,5,9-undecatriene, 5,9-dimethyl-1,4,8-detriene, 4-ethylidene-8-methyl-1,7-nonadiene, 13-ethyl-9-methyl-1,9,12-pentadecatriene, 5,9,13-trimethyl-1,4,8,12-tetradecadiene, 8,14,16-trimethyl-1,7,14-hexadecatriene, 4-ethylidene-12-methyl-1,11-pentadecadiene.
The iodine value which represents non-conjugated diene content in the copolymer is 20 to 36, preferably 20 to 32. When the iodine value is too small, problems arise that the compression set of the sponge rubber becomes inferior and that much amount of a vulcanization accelerator is required due to a slow vulcanization rate, which results in causing a blooming. In contrast, when the iodine value is too large, problems arise that the softness of the sponge rubber is deteriorated and that the costs becomes high.
The Mooney viscosity (i.e., ML 1+4 (121° C.) in Mooney viscosity according to JIS-K-6300) of the copolymer is 100 to 180, preferably 110 to 170, as measured for a mixture formed by compounding 20 parts by weight of an extender oil based on 100 parts by weight of said copolymer. The reason why Mooney viscosity (i.e., ML 1+4 (121° C.) in Mooney viscosity according to JIS-K-6300) is measured for a mixture formed by compounding 20 parts by weight of an extender oil based on 100 parts by weight of said copolymer is that, when Mooney viscosity as an indicator for the molecular weight is measured and the measured Mooney viscosity exceeds 200, sometimes Mooney viscosity can not be exactly measured due to slipping between a rotor for detecting torque and the copolymer caused by the structure of measuring apparatus.
When Mooney viscosity (i.e., ML 1+4 (121° C.) in Mooney viscosity according to JIS-K-6300) as measured for a mixture formed by compounding 20 parts by weight of an extender oil based on 100 parts by weight of said copolymer is too low
Fitch Even Tabin & Flannery
McAvoy Ellen M.
Sumitomo Chemical Company Ltd.
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