Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-10-14
2001-06-19
Mulcahy, Peter D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C423S449200
Reexamination Certificate
active
06248808
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for producing carbon black having silica attached to the surface to have silanol groups present on the surface, and a rubber composition having such carbon black incorporated. The obtained rubber composition is useful for the production of e.g. tire treads or belts.
BACKGROUND ART
“tan &dgr;” is available as in index of heat generation when a vulcanized rubber composition having reinforcing particles incorporated, is subjected to repeated deformation. For example, it is known that tan &dgr; at from 50 to 70° C. may be made small in order to reduce the rolling resistance of a tire tread and to reduce the fuel cost. On the other hand, the damping properties on a wet road surface, etc., are better, when tan &dgr; in the vicinity of 0° C. is larger. As a method for improving this temperature dependency of tan &dgr; i.e. for reducing tan &dgr; at from 50 to 70° C. and increasing tan &dgr; in the vicinity of 0° C., it has been tried to incorporate silica as a filler. For example, JP-A-3-252433 discloses that silica and a silane coupling agent are incorporated to SBR prepared by solution polymerization. Further, JP-A-7-165991 discloses that as a silane coupling agent, a bifunctional one which is reactive with silica and rubber, is particularly excellent.
In this connection, it is known that when particles having silanol groups on the surface, such as silica particles, are kneaded into a diene type rubber together with a silane coupling agent such as bis(3-triethoxysilylpropyl)-tetrasulfone, followed by vulcanization, the particles and the rubber will be bonded via the coupling agent. It is considered that by such a chemical bonding, tan &dgr; in the vicinity of 60° C. of the particles-incorporated vulcanized rubber composition becomes low, and improvement in the physical properties, such as improvement in the abrasion resistance, is observed.
However, in a case where silica is incorporated as a filler, although it is possible to improve the temperature dependency of tan &dgr;, there is a problem that the silica filler has a self agglomerating force which is so strong that it is hardly dispersible in rubber and it is poor in processability. Further, there is another problem that the compound cost increases, since it is necessary to incorporate an expensive silane coupling agent usually as much as from 5 to 15% relative to the silica.
Further, if a silane coupling agent having a sulfur atom as mentioned above, is incorporated without incorporating a silica filler to carbon black, there will be a case where tan &dgr; in the vicinity of 60° C. of the particles-incorporated rubber composition, will be substantially reduced. However, there will be a drawback that the damping properties tend to be low, since the complex modulus of elasticity (E*) or the dynamic modulus of elasticity (E′) is high in a low temperature range (from −10 to 0° C.) under a low strain (from 0.1 to 1%).
On the other hand, it has been proposed to subject carbon black to be incorporated to a rubber composition to surface treatment with silica or a silane. For example, JP-A-53-100190 or JP-A-61-291659 discloses a method of mixing an organic compound or an organometallic compound of silicon dissolved in a solvent or in water, with carbon black, followed by drying. Specifically, as the silicon compound, dimethylpolysiloxane or silicon oil is employed. Further, JP-A-56-38357 proposes hydrophobically surface-treated carbon black having the surface treated with a cyclic alkylpolysiloxane or a silicon compound. JP-A-58-125249 discloses carbon black having the surface coated with a silane coupling agent dissolved in a solvent.
JP-A-63-63755 proposes a method wherein carbon black is dispersed in water, and sodium silicate is neutralized with sulfuric acid, whereby amorphous silica is precipitated on the carbon black surface. However, none of these methods can be said to be suitable for industrial application from the viewpoint of the economy or the process such as removal or recovery of the solvent, or the operation for neutralization. Further, JP-A-4-233976 proposes to chemically modify carbon black with a certain specific organic silicon compound (specifically, a sulfur-containing silane coupling agent having a certain specific structure). However, this method also has a processwise or economical problem, e.g. in the extraction operation or post-treatment for modification. Besides, in these methods for treating carbon black with a surface treating agent such as silica or a silane, it is expected also that the surface treating agent will not sufficiently uniformly attach to the surfaces of all carbon black.
DISCLOSURE OF THE INVENTION
In view of the above problems, the present inventors have conducted an extensive study on a method for attaching silica on the surface of carbon black in order to present reinforcing particles having a visco-elastic property (temperature dependency of tan &dgr;) of a level comparable to silica and having the difficult dispersibility and difficult processability of silica improved to a level comparable to carbon black, and a rubber composition having such reinforcing particles incorporated.
As a result, they have found that by carrying out surface treatment of carbon black by a specific method employing a specific silicon-containing compound, it is possible to have silanol groups present on the surface of carbon black efficiently and effectively, and besides, a rubber composition having such surface-treated carbon black incorporated, exhibits excellent properties. Thus, the present invention has been accomplished.
Namely, the present invention resides in surface-treated carbon black characterized by contacting a silane and/or polysiloxane having all organic groups bonded to silicon via oxygen, to the surface of carbon black at not higher than 200° C., and a rubber composition having such surface-treated carbon black incorporated.
By such a present invention, it is possible to introduce silanol groups to the carbon black surface, whereby reduction of tan &dgr; in the vicinity of 60° C. of a vulcanized rubber composition and improvement of a physical property such as improvement of the abrasion resistance which used to be attempted by incorporating particles having silanol groups such as silica particles, can be accomplished without incorporating particles such as silica.
Besides, it is also possible to overcome the drawback that the damping properties tend to be low, since the complex modulus of elasticity (E*) or the dynamic modulus of elasticity (E′) is high in a low temperature range (from −10 to 0° C.) under a low strain (from 0.1 to 1%) as in the case where a silane coupling agent having a sulfur atom is incorporated.
Besides, with the surface-treated carbon black obtainable by the present invention, it is possible to improve the difficult dispensability and difficult processability as drawbacks of silica to a level comparable to carbon black. Thus, by the present invention, it becomes possible to present reinforcing particles having merits of silica and carbon black simultaneously i.e. reinforcing particles having a visco-elastic property (temperature dependency of tan &dgr;) of a level comparable to silica and having the difficult dispersibility and difficult processability of silica improved to a level comparable to carbon black, and a rubber composition having such reinforcing particles incorporated.
REFERENCES:
patent: 5679728 (1997-10-01), Kawazura et al.
patent: 53-100190 (1978-09-01), None
patent: 63-63755 (1988-03-01), None
patent: 5-295294 (1993-11-01), None
patent: 8-157771 (1996-06-01), None
patent: 8-277347 (1996-10-01), None
Chemical Abstract, AN 99209, vol. 107, No. 12, Sep. 21, 1987, JP 61 291659, Dec. 22, 1986.
Ishida Masami
Mizushima Kiyoshi
Sone Kazuhiro
Mitsubishi Chemical Corporation
Mulcahy Peter D.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Process for preparing surface-treated carbon black and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for preparing surface-treated carbon black and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing surface-treated carbon black and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2506665