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Low loss foam composition and cable having low loss foam layer

A low-loss, composition technology, used in the field of foam compositions and cables containing foam, can solve problems such as flammability of chemicals

Inactive Publication Date: 2006-06-14
NAT RES COUNCIL OF CANADA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] Although hydrocarbons (HCs) or chlorofluorocarbons (CFCs) can be used to make LDPE foam, these chemicals are flammable or are banned by international environmental protection treaties

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 5～7

[0052] Extrusion of the composition using approximately equal proportions of carbon dioxide and HFC-134a

[0053] Table 5 shows the data of Examples 5-7, which can be used for comparison and comparison with the data of Comparative Examples 1-4. These data demonstrate improved properties of foams produced using mixtures of carbon dioxide and HFC-134a. These examples were achieved by maintaining a constant carbon dioxide level while increasing the concentration of HFC-134a co-blowing agent. The density of the extruded foams in Examples 5-7 was significantly lower compared to the control experiments in Comparative Examples 1-4.

[0054] In particular, in Examples 5-7, the content of open cells remained low despite a large drop in density. Assembled cables containing these performance-modified foams show significant improvements in cable performance.

[0055] Components / parameters

Embodiment 8～11

[0057] Extrusion of Foam Compositions Using Various Nucleating Agent Types and Die Diameters

[0058] Table 6 shows the data of Examples 8-11 which can be used for comparison and contrast with the data of Comparative Examples 1-4. The data in Table 6 demonstrate the improved properties of foams made from mixtures of carbon dioxide and HFC-134a. These specific examples focus on the use of various CO 2 / HFC-134a ratio and content of manufactured products.

[0059] Experiments using different conditions, such as different nucleating agents and die diameters, still produced LDPE foams with very low open cell content. Even in the absence of nucleating agents, which lead to a marked increase in pore size, a suitable density and open cell content is still obtained. In addition, 0.25% talc was used instead of azodicarbonamide to obtain suitable density and open cell content. These data therefore indicate that the blowing process using carbon dioxide and HFC-134a as a co-blowing ag...

Embodiment 12～15

[0062] Extrusion of foam compositions under various processing pressures

[0063]Table 7 shows the data for Examples 12-15. These data demonstrate that the foaming process described herein has a wide range of pressure and temperature processing. In particular, low open cell content was maintained and low density was achieved even when the melt pressure was varied from 500 to 540 psi and the melt temperature was varied from 119 to 134°C.

[0064] Components / parameters

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Abstract

The invention relates to a low loss foam composition and cable, such as a coaxial cable. The foam composition is formed by heating an olefinic polymer, such as a high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, or a combination thereof, into a molten state composition, optionally with a nucleating agent. The molten mixture is extruded under pressure through a die with a blowing agent comprising an atmospheric gas, such as carbon dioxide, nitrogen or air, and a co-blowing agent selected from hydrofluorocarbons, hydrochlorofluorocarbons, or perfluoro compounds, such as hfc-134a. The cable is formed by extruding the foam composition onto a signal carrying conductor and sheathing the foam-coated signal carrying conductor in an appropriate conducting shield.

Description

technical field [0001] The present invention relates to foam compositions and cables containing foams. More particularly, the present invention relates to low loss foam compositions and cables containing the foam for use in telecommunications applications. Background technique [0002] Coaxial long-distance communication cables are usually made of a core conductor and a thicker layer of closed-cell foam extruded around the core conductor. This foam-covered semiconductor is encapsulated by a thin metal conductor, which in turn is encapsulated by a thin polymer layer that protects the entire cable from external attack. [0003] Among other factors, the signal transmission capability of a given cable is related to the loss characteristics of the cable. The loss characteristics of the cable are significantly influenced by the dielectric properties of the foam extruded onto the core conductor. The most critical factors controlling the dielectric properties of a foam are the na...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08L23/06C08J9/00C08J9/12C08L23/08C08L23/10C08L23/12C08L23/16
CPCC08J9/127C08J2203/06C08J2203/142C08J2323/02C08L23/06C08L23/0815C08L23/10C08L2203/14C08J9/144C08J9/122C08J2203/182C08J2201/03C08J9/0061C08J2323/06C08J9/103C08J2203/04C08J2423/06C08J2203/204C08L2666/06
Inventor 米歇尔·F.·尚帕涅理查德·让德龙卡罗琳·瓦雄维贾伊·K.·乔普拉休·R.·纳德西塔拉姆·兰帕利
Owner NAT RES COUNCIL OF CANADA
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