Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-08-29
2003-05-13
Teskin, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S079000, C526S087000, C526S295000, C526S313000, C526S329100, C526S331000, C526S335000, C525S105000, C524S552000, C524S562000, C524S563000, C524S565000, C524S566000
Reexamination Certificate
active
06562929
ABSTRACT:
TITLE OF THE INVENTION
Conjugated diene-based rubber and method of producing the same, oil extended rubber and rubber composition containing the same
1. Field of the Invention
The present invention relates to a conjugated diene-based rubber capable of being converted into a vulcanized rubber having a low rolling resistance, an excellent wet skid property, sufficient wearing resistance, tensile strength and the like when incorporating an inorganic filler such as a silica as a reinforcing agent and a method of producing the same, and also to an oil extended rubber containing a conjugated diene-based rubber and an extending oil. The present invention also relates to a rubber composition comprising a conjugated diene-based rubber or an oil extended rubber described above and an inorganic filler and having an excellent processability. This rubber composition gives a vulcanized rubber which is useful especially as a tire tread.
2. Description of the Prior Art
In response to recent demand for low gas mileage of automobile, rubber material such as a conjugated diene-based rubber or the like capable of giving a rubber composition for a tire which has low rolling resistance, excellent wearing resistance and destruction characteristics and whose wet skid resistance, which is a representative index of a driving stability, is high is desired.
Tire rolling resistance can be reduced by lowering hysteresis loss of vulcanized rubber. The hysteresis loss can be evaluated based on various properties. For example, compositions preferably have high impact resilience at 50-80° C., a low tan&dgr; at 50-80° C. or low Goodrich heat release. Compositions with low hysteresis loss include natural rubber, isoprene rubber, butadiene rubber and the like, but these are also associated with the problem of low wet skid resistance.
In recent years, there have been proposed methods of using inorganic filler such as silica and the like to serve as reinforcing agent, or combining inorganic filler with carbon black. Tire treads employing inorganic filler or both inorganic filler and carbon black have low rolling resistance and excellent driving stability, represented by, for example, the wet skid resistance. However, they exhibit a problem of poor wearing resistance, tensile strength and the like for the vulcanized rubber. The cause is believed to be the fact that the affinity of inorganic filler for the conjugated diene-based rubber is lower than that of carbon black, such that a sufficient reinforcing effect cannot be achieved.
In order to increase the affinity between the silica as an inorganic filler and the conjugated diene-based rubber, it has been attempted to use conjugated diene-based rubbers introduced therein functional group with affinity for inorganic filler. For example, there have been proposed a conjugated diene-based rubber introduced a hydroxyl group therein (WO96/23027), a conjugated diene-based rubber introduced an alkoxysilyl group therein (Japanese Patent laid-open publication No. HEI-9-208623) and a conjugated diene-based rubber introduced an alkoxysilyl group and an amino and/or a hydroxyl group therein (Japanese Patent laid-open publication No. HEI-9-208633). However, most conjugated diene-based rubbers with such an introduced functional group exhibit strong interaction with an inorganic filler when the inorganic filler is combined therewith, and this creates such problems as impaired dispersion of the inorganic filler, greater heat release during processing, poor processability and the like.
SUMMARY OF THE INVENTION
The present invention solves the problems associated with a prior art described above and is intended to provide a conjugated diene-based rubber and an oil extended rubber, each of which is capable of being converted into a vulcanized rubber having a low rolling resistance, an excellent wet skid property and sufficient wearing resistance, tensile strength, and the like. Another aspect of the invention is intended to provide a rubber composition capable of being converted into a vulcanized rubber which has an excellent processability and is useful as a tire tread of an automobile or the like.
A rubber composition for formation of a tire tread and the like usually contains a reinforcing agent for the purpose of improving tensile strength and wear resistance, but silica and similar substances do not easily disperse uniformly because of their tendency to aggregate. When using a rubber composition in which the reinforcing agent is not uniformly dispersed, the desired effect of including the reinforcing agent cannot be achieved, while the processability is also notably impaired. For this reason, it has generally been attempted to improve the dispersion properties by also including a silane coupling agent when using a silica as an inorganic filler.
It was discovered that by using a conjugated diene-based rubber having a certain composition in which an unsaturated nitrile monomer unit is contained in a molecular chain a sufficient improvement in the wearing resistance, the tensile strength, and the like as well as the processability can be achieved even with a reduced amount of a silane coupling agent or rather without any silane coupling agent.
The present invention is based on the findings described above and can be described as follows.
1. A conjugated diene-based rubber obtained by copolymerizing monomers containing an olefinically unsaturated nitrile monomer, an aromatic vinyl monomer and a conjugated diene monomer, and is characterized in that the glass transition point of the above-mentioned conjugated diene-based rubber is −60 to 0° C., the difference between the extrapolated temperatures of the initiation and the termination of the above-mentioned glass transition is 20° C. or less, that has a repeating unit comprising {circle around (1)} 9 to 30% by mass of an olefinically unsaturated nitrile monomer unit, {circle around (2)} 10 to 50% by mass of an aromatic vinyl monomer unit and {circle around (3)} 20 to 81% by mass of a conjugated diene monomer unit [where the total of {circle around (1)}, {circle around (2)} and {circle around (3)} is 100% by mass], and that Mooney viscosity [ML
1+4
(100° C.)] is 20 to 200.
2. A method for producing a conjugated diene-based rubber by copolymerizing monomers containing an olefinically unsaturated nitrile monomer, an aromatic vinyl monomer and a conjugated diene monomer, and is characterized in that polymerization is carried by adding the above-mentioned olefinically unsaturated nitrile monomer portionwise to polymerization system and then by adding the remainder of the above-mentioned olefinically unsaturated nitrile monomer intermittently to polymerization system in the case conversion of the total of the charged monomer measured in the course of polymerization is reached 10 to 95%.
3. A method for producing a conjugated diene-based rubber according to 2 above wherein, the initial amount of the above-mentioned olefinically unsaturated nitrile monomer charged before polymerization is preferably 20 to 95% by mass with respect to the total amount of the above-mentioned olefinically unsaturated nitrile monomer to be prepaired.
4. A method for producing a conjugated diene-based rubber by copolymerizing monomers containing an olefinically unsaturated nitrile monomer, an aromatic vinyl monomer and a conjugated diene monomer, and is characterized in that polymerization is carried by adding the above-mentioned olefinically unsaturated nitrile monomer portionwise to polymerization system and then by adding the remainder of the above-mentioned olefinically unsaturated nitrile monomer continuously to polymerization system in the case conversion of the total of the charged monomer measured in the course of polymerization is reached 10 to 95%.
5. A method for producing a conjugated diene-based rubber according to 4 above wherein, the initial amount of the above-mentioned olefinically unsaturated nitrile monomer charged before polymerization is preferably 20 to 95% by mass with respect to the total amount of the above-me
Konno Tomohisa
Tadaki Toshihiro
Udagawa Yoshiyuki
LandOfFree
Conjugated diene-based rubber and method of producing the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Conjugated diene-based rubber and method of producing the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Conjugated diene-based rubber and method of producing the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3018999