Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-03-24
2002-06-11
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S496000, C252S502000, C252S503000, C252S511000, C252S570000
Reexamination Certificate
active
06403697
ABSTRACT:
The present invention relates to carbon black having boron solid-solubilized therein, a method for its preparation and its applications i.e. an electrically conductive composition, a resin composition for a cable, a communication cable and a power cable.
Heretofore, it has been common to incorporate an electrically conductive material such as carbon black to a rubber, a resin or a coating material. As such carbon black, one having a large specific surface area or one having the structure developed, has been preferably employed in order to impart higher electrical conductivity. As an example for application of a conductive resin composition among such conductive compositions, a protective material for a communication cable or a semiconductor layer for a power cable may be mentioned.
A communication cable comprises, as the basic structure, a conductor (such as cupper or aluminum) for conducting communication signals, an insulator (such as a vinyl chloride resin, an ethylene type resin such as cross linked polyethylene, or paper) for preventing short circuiting of conductors, and a protective material (such as lead, an ethylene type resin, a vinyl chloride resin or a polychloroprene rubber) for protecting a collected cable conductor, and it is used, for example, as a city cable, a toll cable, an optical fiber cable, a coaxial cable or a submarine cable.
On the other hand, a power cable comprises, as the basic structure, a conductor (such as cupper or aluminum) for conducting an electric power, an inner semiconductor layer (such as a carbon black-containing ethylene/vinyl acetate copolymer resin) for field relaxation, an insulating layer (such as cross-linked polyethylene or ethylene propylene rubber), an outer semiconductor layer (such as a carbon black-containing ethylene/vinyl acetate copolymer resin) for field relaxation, a shielding layer (such as a cupper tape) and a protective material (such as a vinyl chloride resin) for protecting the cable, and it is used, for example, as a CV cable (cross-linked polyethylene insulated vinyl sheath cable) such as a single core CV cable, a three core CV cable or a triplex CV cable, or a PN cable. Further, there is a power cable having a structure such that a cloth tape is interposed between the shielding layer and the protective material.
Such a communication cable or a power cable (hereinafter sometimes generally referred to simply as “a able”) is widely used, as the maintenance control is easy. However, one of problems to be solved is how to further improve the flexibility.
A protective material for a communication cable is required to have functions to protect the interior of the cable from damage by an external mechanical factor, to prevent humidity in air from reaching to. the insulating layer, to provide a return circuit for a fault current and to shield disturbance due to external electromagnetic waves. Likewise, a protective material for a power cable is required to have, in addition to the above functions of the protective layer for a communication cable, a function to shield induction electromagnetic waves generated by a high voltage current against the exterior. Such electromagnetic wave-shielding effects are closely related to electrical conductivity. Namely, if the electrical conductivity is improved, the electromagnetic wave-shielding effect will also be improved. Therefore, at present, as a protective material, a combination of a metal sheath and a corrosion preventive material made of a resin composition, is employed. As a: resin for such a resin composition, chloroprene rubber, a vinyl chloride resin or polyethylene is, for example, used. Especially for a small-size cable, flexibility is desired to increase the degree of freedom in wiring. Accordingly, use of a resin composition having carbon black loaded, is increasing, and it is presently desired to develop an inexpensive and highly conductive resin composition for the protective material.
On the other hand, an internal semiconductor layer and an external semiconductor layer of a power cable are made of a molded product having carbon black incorporated to an ethylene type copolymer resin such as an ethylene/vinyl acetate copolymer, an ethylene/ethyl acrylate copolymer or an ethylene/butyl acrylate copolymer, having the content of a copolymer component such as vinyl acetate, ethyl acrylate or butyl acrylate increased to a level of at least 20%, in order to improve the field relaxation between the adjacent conductor and insulating layer or to improve the field relaxation between the insulating layer and the metal sheath of the protective material. However, such a copolymer component is expensive, and the cost of resin may increase. Accordingly, it is desired to develop a semiconductor layer made of an ethylene type copolymer resin having a small content of such a copolymer component and having high fluidity and high electrical conductivity.
The present inventors have attempted to satisfy the above demand by increasing the loading amount of carbon black to an ethylene type copolymer resin, but if the loading amount is increased to such a level at which the desired electrical conductivity can be achieved, the flexibility of the obtained molded product tends to remarkably deteriorate, and the object cannot be accomplished. The carbon black used here was a conventional product (commercial product). For a high voltage or super high voltage CV cable semiconductor layer with a working voltage being at least 33 KV, acetylene black having an iodine adsorption number of from 85 to 100 mg/g was used from the viewpoint of adhesion and high purity. For a CV cable semiconductor layer with a working voltage of less than 33 KV, furnace black was used to facilitate peeling of the resin at the time of application. Further, as a protective material, a molded product having furnace black loaded to a low density polyethylene (LDPE: low-density polyethylene), was used.
When ketchen black capable of imparting high electrical conductivity with a small loading amount, is used instead of furnace black, the electrical conductivity was improved by a high specific surface area, but the tendency for flexibility was the same as a conventional product, and thus the flexibility was not sufficient although high conductivity was obtained. Rather, high loading of ketchen black tended to increase adsorbed water because of the high specific surface area, thus leading to a problem such as deterioration of the resin composition or the resin molded product.
As described above, if carbon black having a high specific surface area such as ketchen black which used to e employed to provide high electrical conductivity, is incorporated to a rubber, a resin or a coating material, the viscosity tends to remarkably increase, and the operation efficiency during mixing or the handling efficiency tends to deteriorate. Therefore, there has been a limitation in improving the electrical conductivity by increasing the loading amount.
The present invention has been made in view of the above problems, and it is an object of the present invention to provide carbon black which has a large conductivity-imparting effect and which does not increase the viscosity like conventional high specific surface area carbon black even if incorporated in a large amount to a rubber, a resin or a coating material, a method for its preparation and its applications i.e. an electrically conductive composition, a resin composition for a cable, a communication cable and a power cable.
Namely, the present invention provides:
Carbon black having boron solid-solubilized therein, which has an electrical resistivity of not higher than 0.1 &OHgr;cm, as measured in accordance with JIS K1469. Preferably, the amount of boron solid-solubilized, is from 0.6 to 3.0 wt %.
A method for preparing boron solid-solubilized carbon black, which comprises a thermal decomposition reaction and/or a combustion reaction of a hydrocarbon, wherein the thermal decomposition reaction and/or the combustion reaction is carried out in the presence of a boron source. It is particularl
Hara Hiroyuki
Mitsunaga Toshikatsu
Tsuruta Kazuyoshi
Yamasaki Yoshiteru
Cain Edward J.
Denki Kagaku Kogyo Kabushiki Kaisha
Lee Katarzyna W.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Carbon black, method for its preparation and its applications does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Carbon black, method for its preparation and its applications, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Carbon black, method for its preparation and its applications will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2953881