# US 7,411,023 B2 · Pipe for hot fluids

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- Number: US 7,411,023 B2
- Document ID: US7411023B2
- Status: Granted
- Kind: B2
- Application number: 10/489,088
- Filed: 2002-10-15
- Published: 2004-12-02
- Granted: 2008-08-12
- Earliest claimed: 2001-10-16
- Assignees: Borealis Technology Oy
- Inventors: Magnus Palmlof
- Web page: https://patentgrep.com/patent/US7411023B2

## CPC

- C08L 23/06: Polyethylene
- C08L 23/0815: {with aliphatic 1-olefins containing one carbon-to-carbon double bond}
- C08L 2205/02: containing two or more polymers of the same C08L -group
- C08L 2205/025: containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
- Y10T 428/139: Open-ended, self-supporting conduit, cylinder, or tube-type article
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A polymer pipe for hot fluids, usually hot water is described. The pipe is characterised in that it comprises a multimodal polyethylene with a high molecular weight (HMW) fraction and a low molecular weight (LMW) fraction where said HMW fraction has a density of at least 0.920 g/cm3, and that the multimodal polyethylene has a density of 0.921-0.950 g/cm3 and has a time to failure at 95° C. and 3.6 MPa of at least 165 h determined according to DIN 16 833 and a modulus of elasticity of at most 900 MPa determined according to ISO 527-2/1B. Preferably, the multimodal polyethylene is a bimodal polyethylene, the LMW fraction having a density of 0.955-0.975 g/cm3, the HMW fraction having a density of 0.920-0.940 g/cm3, and the weight ratio of the LMW fraction to the HMW fraction being from 30:70 to 55:45.

## Claims

### Claim 1

A polymer pipe for hot fluids, comprising a multimodal polyethylene comprising:
a high molecular weight (HMW) fraction, and
a low molecular weight (LMW) fraction,
wherein said HMW fraction has a density of 0.922-0.930 g/cm3 and said LMW fraction has a density of 0.955-0.975 g/cm3, the multimodal polyethylene having:
a density of 0.921-0.950 g/cm3,
a time to failure at 95° C. and 3.6 MPa of at least 165 h determined according to DIN 16 833, and
a modulus of elasticity of at most 900 MPa determined according to ISO 527-2/1B, and wherein the polymer pipe is in the form of a pipe and is constructed to convey water at a temperature of at least 60° C.

### Claim 2 (depends on 1)

A pipe as claimed in claim 1, wherein the HMW fraction is an ethylene copolymer.

### Claim 3 (depends on 2)

A pipe as claimed in claim 2, wherein the HMW fraction is a copolymer of ethylene and a comonomer selected from the group consisting of 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

### Claim 4 (depends on 1)

A pipe as claimed in claim 1, wherein the LMW fraction has an MFR2=1-1000 g/10 min.

### Claim 5 (depends on 1)

A pipe as claimed in claim 1, wherein the weight ratio between the LMW fraction and the HMW fraction lies in the range from 30:70 to 55:45.

### Claim 6 (depends on 1)

A pipe as claimed in claim 1, wherein the multimodal polyethylene has a density of 0.921-0.950 g/cm3, the LMW fraction is an ethylene homopolymer with a density of 0.955-0.975 g/cm3, and the HMW fraction is an ethylene copolymer with a density of 0.922-0.930 g/cm3, the weight ratio of the LMW fraction to the HMW fraction being from 30:70 to 55:45.

### Claim 7 (depends on 1)

A pipe as claimed in claim 1, wherein the pipe is a floor heating pipe.