US1628986A - Insulating material - Google Patents

Description

Patented May 17, 1927.

UNITED STATES v. PATENT OFFICE.

ARCHIE R. KEMP, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

INSULATING MATERIAL.

No Drawing.

This invention relates to insulated cables and particularly to a plastic material for use in joining or covering sections of such cables.

\Vhen two sections of cable comprising an electric conductor covered with a vulcanized sheathing are spliced together to provide a mechanically and electrically continuous conductor, it is necessary that the splice be provided with a suitable insulating covering. It is also sometimes necessary to cover a portion of such conductor which may become exposed due to the removal of the associated vulcanized sheathing, with a substitute covering. Since in such cases the covering must firmly unite with the insulation of the remainder of the cable, it is desirable that the covering be readily adhesive and he of such a character that it may be vulcanized within a short period of time without deleteriously affecting the previously vulcanized sheathing adjacent thereto.

It is the principal object of this invention to enable the covering of splices in an insulated cable with a plastic compound which may be rapidly vulcanized without injuring the cable insulation and which forms a coating firmly united with the vulcanized coating on the remainder of the cable, the joint thus formed having a permanently high insulation resistance.

To attain this object, the invention contemplates a plastic material which may be readily fashioned about the conductor splice, which may be rapidly vulcanized without inj uring the insulation of the adjacent cable and which will unite firmly with the cable insulation and be of sufiicient toughness to withstand any mechanical injury to which it may be subjected in service.

This invention is applicable to the general forms of rubber insulated cable. In the manufacture of such an insulated cable, a thin layer of substantially pure gum rubber is formed around the conductor and plastic vulcanizable material is then extruded over the previously applied rubber and the core sheathing is vulcanized in any suitable manner. IVhen it is desired to cover a splice, or an otherwise exposed portion of such conductor, it is necessary to employ a material having the characteristics referred to above. A plastic material which has been Serial No. 673,822.

found to give very satisfactory results under the most severe conditions consists essentially of the following ingredients and in the proportions named:

These ingredients are mixed intimately according to the usual well known methods. The litharge acts as an accelerator and the comparatively large percentage which is used makes it possible to obtain the desired degree of vulcanization in a very short period of time. It is thus possible not only to vulcanize the plastic material about the splice without injuring the vulcanized covering adjacent thereto but also to quickly complete the vulcanizing process. This is of particular importance in connection with the laying of submarine cables which are necessarily spliced aboard ship.

\Vhile the formula given above under usual conditions gives the most satisfactory results, the proportions may be varied somewhat to suit particular conditions.

Various methods may be employed for fashioning this plastic material on the spliced conductor but the method preferred is disclosed in detail in my Patent No. 1,586,811 granted on June 1, 1926.

As a result of exhaustive testsit has been demonstrated that cable splices insulated with a jacket of plastic material of the type described are capable of withstanding the most severe conditions to which they are apt to be subjected in service and are satisfactory t'rom the standpoint of insulation resistance.

\Vhat is claimed is:

A jointing compound for rubber insulated cables comprising the following ingredients in approximately the proportions named, rubber 40%, zinc oxide 34%, litharge 20%,

sulphur 4%, parafiine 2%.

In witness whereof, I hereunto subscribe my name this 15th day of October A. D.,

ARCHIE R. KEMP.