Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-06-25
2001-10-30
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S256000, C526S258000
Reexamination Certificate
active
06310158
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a sulfur vulcanizable novel butyl rubber and a rubber composition having an improved processability and vulcanized physical properties containing the same.
2. Description of the Related Art
Heretofore, butyl rubber is used as an inner liner, bladder of a tire, gasket, diagram, hose, belt, rubber vibration isolator, etc., utilizing the characteristics thereof (e.g., gas impermeability, vibration absorbance property). However, since butyl rubber accelerates the vulcanization, various attempts have been made to facilitate blending thereof with the other diene rubbers and various halogenated butyl rubbers having improved such properties. However, the butyl rubber has problem in that the weather resistance is not sufficient because the butyl rubber is of unsaturated type. Especially, the butyl rubber cannot be used as, for example, a sidewall of a tire, etc. Therefore, it has been proposed in U.S. patent application Ser. No. 88/199665 (or EP-A-344021) that butyl rubber is obtained by halogenating a copolymer containing p-alkyl styrene unit. This butyl rubber is surely excellent in the weather resistance etc., and therefore, the butyl rubber becomes usable as a tread, sidewall etc. of the tire. However, since the halogen group of the butyl rubber is highly reactive, the butyl rubber is reacted with other compounding agents such as silica and zinc oxide, and therefore, the new problem cause that, when silica is added, the viscosity is increased. Furthermore, when zinc oxide is initially compounded, there occurs a problem in that the zinc oxide is reacted with the butyl rubber. Thus, the timing at which zinc oxide is added should be limited. In addition, since this butyl rubber does not possess an unsaturated group, the vulcanization with sulfur is difficult and the covulcanization together with diene rubbers with sulfur are not possible in general, and therefore, the problems occur in the abrasion resistance, etc.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a butyl rubber having an excellent weather resistance, which is capable of being vulcanized with sulfur without the increase in the viscosity when silica is compounded and without limitation of timing of adding zinc oxide.
In accordance with the present invention, there is provided a butyl rubber comprising at least one repeating unit selected from the group consisting of those having the formulae (I) and (II):
wherein R independently represents a hydrogen atom or at least one group selected from the group consisting of methyl, ethyl, propyl, isopropyl and butyl groups.
In accordance with the present invention, there is also provided a rubber composition comprising 100 parts by weight of a rubber component containing 3-100% by weight of the above-mentioned butyl rubber optionally blended with a diene rubber and 0.1 to 10 parts by weight of a sulfur vulcanizing agent.
In accordance with the present invention, there is further provided a rubber composition comprising 100 parts by weight of a rubber component containing 3-100% by weight of the above-mentioned butyl rubber and 10-100 parts by weight of silica.
In accordance with the present invention, there is further provided a rubber composition comprising 100 parts by weight of a rubber component containing 3-100% by weight of a halogenated butyl rubber obtained by halogenating a butyl rubber comprising isobutyrene and p-alkylstyrene and 0.3-10 parts by weight of at least one compound having the formulae (III) and (IV):
wherein R independently represents a hydrogen atom or at least one group selected from the group consisting of methyl, ethyl, propyl, isopropyl and butyl groups, and M represents Na, K, Zn or Ti.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In order to accomplish the above-mentioned object of the present invention, the inventors of the present invention has extensively studied and has come to realize the reaction of the specified functional group to the halogen group of the halogenized alkylstyrene residue of the butyl rubber. Thus, the present invention was completed on the basis of those findings.
The present invention provides a butyl rubber having the repeating unit of the formulae (I) and/or (II). The butyl rubber according to the present invention preferably contains 70 mol % or more of the isobutyrene unit and may further contain, iso-monoolefin residue other than isobutyrene or the remaining unhalogenized p-alkylstyrene residue, so long as the desired properties of the vulcanized product are not impaired.
The content of the repeating unit (I) and/or (II) in the butyl rubber according to the present invention is preferably 0.1 to 10 mol %, more preferably 0.5 to 5 mol %, based upon the butyl rubber. If this content is too small, the vulcanization tends to be insufficient. Contrary to this, if too excessive the elongation, etc. of the vulcanized product tends to be decreased.
Although the butyl rubber according to the present invention can be obtained by copolymerizing the corresponding monomer with isobutyrene, it is preferable, in view of the polymerizability, stability and economical advantage, that the butyl rubber is produced by the method in which the corresponding halogenated butyl rubber is reacted with 2-mercapto benzothiazole or its amine or metal salt or dialkyl dithiocarbamic acid or its amine or metal salt. These reactions can be carried out by dissolving the above halogenated butyl rubber in a solvent such as toluene, hexane, cyclohexane, followed by reacting with the above-mentioned corresponding compound at a temperature of, for example, 60 to 120° C. for, for example, 5 to 30 minutes. Alternatively, this reaction can be carried out by mixing the above-mentioned compounds directly, or after dissolving in water, solvent, etc., by means of a pressurized kneader, Brabender type mixer, etc., for example, at 60 to 180° C. for 2 to 30 minutes.
Since the above-mentioned substituents have such structures that they easily generate radicals upon heating, the compounds are self-crosslinked by heating. Alternatively, the crosslinking is also carried out in the presence of a sulfur or a diene rubber upon heating by a sulfur vulcanization or a radical reaction. The amount of the sulfur is preferably 0.1 to 10 parts by weight, more preferably 0.5-5 parts by weight, based upon 100 parts by weight of the rubber, as in the case of the conventional halogenized butyl rubber.
The sulfur vulcanizing agents (or sulfur-containing vulcanizing agents) usable in the present invention include, for example, sulfur such as powder sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur and sulfur-providing compounds such as polysulfide rubbers disclosed in, for example, “Rubber Industry Text Book (new edition) page 169 published by Japanese Rubber Association on Nov. 15, 1973”. More specifically poly(ethylene tetrasulfide), poly(propylene tetrasulfide), poly(tetraethylene sulfide), etc. may be mentioned. In addition, sulfur-based vulcanizing agents recited in “Updated Technology of Additive for Polymer (in Japanese), pages 298-299, Jan. 6, 1988, published by CMC. More specifically, N,N′-dithio di(polymethylene imine), N,N′-bis(2-benzothiazoylthio)piperazine, etc. may be mentioned.
In addition, so-called SSO type, SSS type vulcanization accelerator (e.g., 2-4-di(O,O′-diisopropylphosphorotrithioyl)-6-morpholino-1,3,5-triazine, 2-(O,O′-diisopropylphosphorotrithioyl)-4,6-di(N,N-diethylamino-1,3,5-triazine) disclosed in JP-A-47-9488, JP-A-47-5391, JP-B-57-15611 may be preferably used as the sulfur-providing compound according to the present invention.
As the blend with diene rubbers, the blending amounts may be freely changed depending on the intended use. Examples of diene rubbers usable in the present invention are various polybutadiene rubbers (BR), various styrene-butadiene copolymer rubbers (SBR), various acrylonitrile-butadiene copolymer rubbers (NBR), various ethylene-propylene copolymer rub
Ishikawa Kazunori
Yatsuyanagi Fumito
Arent Fox Kintner & Plotkin & Kahn, PLLC
Pezzuto Helen L.
The Yokohama Rubber Co. Ltd.
LandOfFree
Sulfur-vulcanizable butyl rubber and rubber composition... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sulfur-vulcanizable butyl rubber and rubber composition..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sulfur-vulcanizable butyl rubber and rubber composition... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2569099