# US 2021/0241940 A1 · Flame retardant electrical cable

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- Number: US 2021/0241940 A1
- Document ID: US20210241940A1
- Status: Published application
- Kind: A1
- Application number: 17/049,684
- Filed: 2018-04-26
- Published: 2021-08-05
- Earliest claimed: 2018-04-26
- Assignees: Prysmian S.p.A.; POLITECNICO Dl MILANO
- Applicants: Prysmian S.P.A.; POLITECNICO Dl MILANO
- Inventors: Vito SCRIMA; Luigi CAIMI; Massimo GOLA; Attilio CITTERIO
- Web page: https://patentgrep.com/patent/US20210241940A1

## CPC

- C01B 32/174: Derivatisation; Solubilisation; Dispersion in solvents
- H01B 7/295: using material resistant to flame
- C08F 10/02: Ethene
- C08K 3/041: {Carbon nanotubes}
- C08K 3/36: Silica
- B82Y 40/00: Manufacture or treatment of nanostructures
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

Disclosed herein are flame-retardant electric cables (10) having a core containing an electric conductor (11) and an electrically insulating layer (12) made from a flame-retardant polyolefin-based composition including a) a cross-linked polyolefin as base polymer, b) silica, and c) carbon nanotubes, wherein the amount of silica is from 5 wt % to 10 wt % of the polyolefin-based composition, and the amount of carbon nanotubes is from 0.5 wt % to 2 wt % of the polyolefin-based composition. Such cables have improved flame retardant performances, especially regarding a lower occurrence of droplets during burning, which render them capable of being certified in higher classes of the current international standards, for example of the standard EN 50399:2011/A1 (2016).

## Claims

### Claim 1

A flame-retardant electric cable having a core comprising an electric conductor and an electrically insulating layer made from a flame-retardant polyolefin-based composition comprising:
a) a cross-linked polyolefin as base polymer;
b) silica; and
c) carbon nanotubes,
wherein an amount of the silica is from 5 wt % to 10 wt % of a weight of the polyolefin-based composition, and an amount of carbon nanotubes is from 0.5 wt % to 2 wt % of the weight of the polyolefin-based composition.

### Claim 2 (depends on 1)

The flame-retardant electric cable according to claim 1, wherein the cross-linked polyolefin is selected from the group consisting of a polyethylene homopolymer and a polyethylene copolymer.

### Claim 3 (depends on 1)

The flame-retardant electric cable according to claim 1, wherein the silica is an amorphous silica.

### Claim 4 (depends on 1)

The flame-retardant electric cable according to claim 1, wherein the silica is a powder material comprising particles having a substantially spherical shape.

### Claim 5 (depends on 1)

The flame-retardant electric cable according to claim 1, wherein the carbon nanotubes are multi-walled nanotubes.

### Claim 6 (depends on 1)

The flame-retardant electric cable according to claim 1, wherein the polyolefin-based composition further comprises talc.

### Claim 7 (depends on 6)

The flame-retardant electric cable according to claim 6, wherein a total amount of the talc and the silica is up to 10 wt % with respect to the weight of the polyolefin-based composition.

### Claim 8 (depends on 6)

The flame-retardant electric cable according to claim 6, wherein the polyolefin-based composition further comprises graphene.

### Claim 9 (depends on 8)

The flame-retardant electric cable according to claim 8, wherein an amount of the graphene in the flame-retardant polyolefin-based composition is up to 0.2 wt % with respect to the weight of the polyolefin-based composition.

### Claim 10 (depends on 8)

The flame-retardant electric cable according to claim 8, wherein graphene is in the form of platelets.

### Claim 11 (depends on 3)

The flame-retardant electric cable according to claim 3, wherein the silica is a powder material comprising particles having a substantially spherical shape.