JPS61166855A - Cable filled with polybutylene gel - Google Patents

Abstract

PURPOSE:A polybutylene gel for filling cable that is composed of a soft hydrocarbon processing oil and an isotactic butene-1 (co)polymer, thus being thermally reversible lower than the temperature at which the cable is damaged and showing slow formability. CONSTITUTION:The gel is composed of (A) 2-8wt%, preferably 4-7wt% of butene-1 (co)polymer containing 0-10wt% of 2-5C comonomers, (B) 0-10wt%, preferably 4-6wt% of styrene-ethylene-butylene-styrene block copolymer and (C) 82-98wt%, preferably 87-96wt% of naphthaenic or paraffinic oil containing 0-25wt% of aromatics.

Description

DETAILED DESCRIPTION OF THE INVENTION Background of the Invention Cables for power, electronic (telephone) transmission, underwater oil exploration, hydroacoustic cables and many other applications are
Since the 1970s, they have been filled with various materials for protection against water ingress.

Flooding occurs when water penetrates into local holes in the cable sheath and flows freely, often hundreds of feet, as far as the physical processes for water spreading and transport permit. This not only unbalances the capacity of the transmission cable line, but also introduces more potential corrosion locations in proportion to the length of the wet wire. The service life of a wire immersed in water is clearly shorter than a wire that is dry.

A widely used solution is to prevent water ingress by simply filling the voids in the cable with a water-insoluble filler material that envelops the cable components. However, although this physical function of cable fill material is simple, the selection of material is not so simple. Among the many important considerations for materials used in this application are the material's hydrophobicity, low temperature properties,
These include flow characteristics at high temperatures, the maximum usable temperature of the coating material ('upper limit temperature'), processing characteristics, handling characteristics, dielectric properties, toxicity, and price.

Materials that meet most of these criteria and are widely used are those of September 21, 1971 and 1973, respectively.
U.S. Patent No. 3.607.48, published on February 20,
No. 7 and No. 3.717.716. These materials are essentially petroleum jelly mixed with a polymer, usually polyethylene, to provide consistency and prevent flow at warm temperatures below the upper temperature limit of use.

Similar hydrophobic coating materials have been proposed for filling reservoirs in junction caps. For example, U.S. Pat. It describes a mixture of low viscosity oils with reduced viscosity.

U.S. Pat. No. 4,259,540 discloses styrene-ethylene- Butylene-styrene-block copolymers, polyethylene and up to 5
discloses the use of paraffinic or naphthenic oils containing % aromatic oils.

However, all of these above-mentioned coating materials must be heated to a temperature above the upper temperature limit of the material during the filling operation. The upper temperature limit for a material is the temperature above which the material cannot be used in a cable. Filling of most materials requires a time-consuming process to heat the coating material to a consistency that can be pumped for filling.

There has been a long-standing desire for a sheathing material that can be processed into cables at temperatures well below the ``upper wettability limit'' of the sheathing material while meeting the requirements for filler materials. do. Traditionally used sheathing materials must be heated to a temperature sufficiently above the melting point of the material (the upper temperature limit for use) to reduce the viscosity of the fluid sufficiently to allow filling of the cable. and required heating of the cable. This heating requires a lot of energy and can damage some of the electrical components in the cable. It also precludes the use of cable component materials that have advantageous properties but cannot withstand the high filling temperatures of these coating materials.
Additionally, there has long been a need for coating materials that are thermally reversible. This means that the covering material can be removed and replaced any number of times at temperatures below those that would damage the cable during maintenance. The thermally reversible coating material can be heated to a liquid state and then cooled to a gel state any number of times without degrading the properties of the filler material or cable components. This is especially true in underwater hydroacoustic cables, which are generally not permanently installed, but where the use of such an invention is paramount.

SUMMARY OF THE INVENTION The present invention provides a cable that can be heated to a liquid state and cooled to a gel state any number of times below temperatures that would damage the cable, thereby allowing the gel to be removed and replaced during maintenance. It includes slow-forming, thermally reversible gels that can be used. Gels are slowly moldable such that the viscosity of the clear liquid increases over hours to days to form a gel. This is the time during which the cable must be filled before the gel material becomes too viscous and will no longer flow, or the gel must be removed during maintenance.

The gel is based on light hydrocarbon ester oil and isotactic butene-1 polymer or butene-1 copolymer. The filler material or gel coating compound comprises about 2% by weight to about 8% by weight butene-1 polymer or copolymer, where the butene-1 polymer or copolymer comprises about 0% to about 8% by weight from about 0% to about 10% by weight styrene containing about 10% C2-Cs comonomer.
It consists of an ethylene-butylene-styrene block copolymer and a naphthenic or paraffinic oil having an aromatic content of about 82% by weight to about 98% by weight, up to 25% by weight. The coating compound preferably contains about 6% by weight of a butene-1 polymer or copolymer, where the butene-1 polymer or copolymer preferably contains about 6% by weight of a comonomer, preferably by weight. about 5
% of 5-EB-S copolymer and a naphthenic or paraffinic oil, preferably having an aromatic content of about 89% by weight, preferably about 15% by weight. . The C2-C comonomer is preferably an ethylene monomer.

The present invention also encompasses cables or other conduits requiring protection against water containing the above-described coating compound.

DETAILED DESCRIPTION OF THE INVENTION The coating compound or gel of the present invention has the following properties: 1) Above the gel temperature, the material is a clear, low viscosity fluid; 2) After cooling to room temperature, the viscosity remains for several hours to several days. 3) As it forms a gel, it becomes translucent; 4) The gel can be removed and replaced during maintenance. 5) The melting temperature, molding temperature and molding time of the gel are controlled by the copolymerization of the polybutylene polymer component in the base polymer or by polymerization. Can be controlled by selection of coalescence and 11 degrees.

6> The gel is hydrophobic and protects the cable from water leakage.

The gel is based on light hydrocarbon process oils and isotactic butene-1 polymers or butene-1 copolymers. Because of their oil compatibility and crystallinity, isotactic polymers or copolymers dissolve in oil above the melting temperature of the polymer. Once dissolved, these polymers exhibit very slow recrystallization from solution and formation of a gel network upon decreasing temperature, and at temperatures significantly below the melting temperature of the gel, ca. The material remains fluid for 48 hours. Finally, a polymeric polybutylene crystallite is formed and becomes network-linked to form a translucent gel.

The presence of ethylene comonomer has been found to reduce both the melting point of the gel and the rate of crystallization.

Example 1 Isotactic butene-1 homopolymer was heated with H at 120° C. to give a solution containing 6% polymer.
Dissolved in Vl 100N oil.

As the solution temperature was lowered, the viscosity began to rise rapidly at about 40°C (this temperature being the minimum filling temperature) and continued to rise until it formed a firm gel within 1 hour of reaching room temperature. The resulting gel had a melting point of approximately 80°C.

Example 2 6% DP8010 isotactic butene-1 containing 5.7% ethylene comonomer by weight was
Dissolved in 100N oil. When the solution was cooled from 128°C, the temperature required for dissolution, the viscosity began to increase at about 30°C.

Within 24-48 hours of the start of the cooling process, the solution material formed a viscous, usable gel. The gel produced is 55~
It had a melting point of 60°C.

Example 3 The ethylenic comonomer-containing polybutene-1 gel of Example 2 is filled into a suitable cable within 24-48 hours after initial cooling from solution. The cable is ready for use within about 12 hours after such filling.

The addition of a comonomer that is 02-Cs comonomer and can range from 2 to 8%, but is preferably about 6% ethylene comonomer, has a dramatic effect on the properties of the gel. It is clear that there are. Besides, 1
It is believed that many hydrocarbon fluids with molecular weights greater than 50 are gelled by isotactic butene-1 homopolymers and copolymers. For example, HVl 100N oil with an aromatic content of 16% is used.

Shellflex o"+3, containing about 24% aromatic content, available from Shell Oil Co., Hughston, Texas, may also be used as a suitable oil, and may similarly be used as - Saper 120LW, which can be obtained from the mallow, has an aromatic content of less than 5%.

Blends of microcrystalline wax and polybutylene, such as Shellmax 500, available from Shell Oil Company, Hughston Texas, are harder, gels that form somewhat more quickly than gels according to the present invention.
It is noted that this results in a more opaque gel.

In addition, the addition of about 0% by weight to about 10% by weight of Kraton OG thermoplastic rubber, available from Shell Oil Company, Hughston Texas, has been shown to improve gel formation with a slight decrease in gel formation time. Increase the strength and transparency of.

Referring to FIG. 1, it can be seen that the coating compound or gel according to the invention fills at 55-60°C, well below the use temperature of polybutene-1 of 80°C. The firm gel formation temperature is 30C, thus the filling range is 50°C ranging from 80°C to 30°C.
℃ range.

If a filler material consisting of wax or rubber is used,
Such filler materials must be filled at temperatures higher than the operating temperature of polybutene-1, 80 DEG C., as shown in FIG. This, of course, requires an additional time-consuming and costly heating step before filling, as well as reheating each time the cable needs to be refilled due to leaks or other problems. Tighten if necessary. The use of such materials also precludes the use of cable components sensitive to temperatures above 80°C.

The present invention not only provides a slow formability that allows sufficient time to fill the cable without additional heating steps, but also allows the cable to later rupture and remove the gel material and/or reincorporate it into the cable. Thermal reversibility so that when filling is required, the gel material can be heated to a solution and cooled to a full degree to form a gel any number of times without any loss of the desired filling properties of the gel material. It also includes gel materials that also have

Various additional modifications and extensions of the invention, such as to various types of cables or no cables at all, will be apparent to those skilled in the art.

In principle, all changes and modifications in reliance on the teachings thereof by which the invention is advanced are duly considered to be within the spirit and scope of the invention.

[Brief explanation of the drawing]

FIG. 1 shows the relationship between the upper temperature limits for use of polybutylene gels, the temperatures required for filling conventional coating materials such as wax, rubber, etc., and the temperatures at which coating gel formulations of the present invention can be filled. It is a graph showing a relationship. Figure 1

Claims (1)

Claims: 1. from about 2 percent by weight to about 8 percent by weight of a butene-1 polymer or copolymer, wherein the butene-1 polymer or copolymer comprises from about 0 percent by weight to about 8 percent by weight. from about 0 percent by weight to about 10 percent by weight of a styrene-ethylene-butylene-styrene block copolymer and from about 82 percent by weight to about 98 percent by weight of naphthenes. slow moldability for filling cables at or below service temperatures of polybutylene, comprising a polybutylene based or paraffinic oil, wherein the oil has an aromatic content of from about 0 percent by weight to about 25 percent by weight; A thermally reversible coating gel compound. 2. The coating compound comprises about 4 percent by weight to about 7 percent by weight butene-1 polymer or copolymer;
wherein the butene-1 polymer or copolymer comprises about 3 percent by weight to about 8 percent by weight of the C_2-C_5
comonomers; about 4% by weight to about 6% by weight of the styrene-ethylene-butylene-styrene block copolymer; and about 87% by weight to about 96% by weight of the naphthenic or paraffinic oil. , where the oil is about 5 percent by weight to about 2 percent by weight
A coating compound according to claim 1, having an aromatic content of 5 percent. 3. The coating compound comprises about 6 percent by weight of the butene-1 polymer or copolymer, wherein the butene-1 polymer or copolymer comprises about 6 percent by weight of the C_2-C_
about 5 percent by weight of the styrene-ethylene-butylene-styrene block copolymer; and about 89 percent by weight of the naphthenic or paraffinic oil, wherein the oil is about 15 percent by weight. A coating compound according to claim 1, having an aromatic content of . 4. a cable body containing a slowly moldable, thermally reversible coating compound, wherein the coating compound comprises from about 2 percent by weight to about 8 percent by weight of a butene-1 polymer or copolymer; The butene-1 polymer or copolymer contains from about 0 percent by weight to about 1 percent by weight.
Contains 0 percent C_2-C_5 comonomer,
and about 92 percent by weight to about 98 percent by weight naphthenic or octene oil, wherein the oil has an aromatic content of about 0 percent by weight to about 25 percent by weight. A cable that can be used for cold filling without any damage and can be easily repaired. 5. The cable of claim 4 which can contain from about 0 percent by weight to about 10 percent by weight of a styrene-ethylene-butylene-styrene block copolymer. 6. The coating compound comprises about 4 percent by weight to about 7 percent by weight butene-1 polymer or copolymer;
wherein the butene-1 polymer or copolymer comprises about 3 percent by weight to about 8 percent by weight of the C_2-C_5
comonomers; from about 4 percent by weight to about 6 percent by weight of a styrene-ethylene-butylene-styrene block copolymer, and from about 87 percent by weight to about 92 percent by weight of said naphthenic or paraffinic oil; 5. The cable of claim 4, wherein the oil has an aromatic content of about 5 percent by weight to about 25 percent by weight. 7. The coating compound comprises about 6 percent by weight of a butene-1 polymer or copolymer, wherein the butene-1 polymer or copolymer contains about 6 percent by weight of C_2-C_
about 5 percent by weight of the styrene-ethylene-butylene-styrene block copolymer; and about 89 percent by weight of the naphthenic or paraffinic oil, wherein the oil is about 15 percent by weight. 5. A cable according to claim 4, having an aromatic content of .