Method of producing polypropylene spunbond fibers

Patent metadata

Field	Value
Publication number	US-9702060-B2
Application number	US-201414332750-A
Country	US
Kind code	B2
Filing date	Jul 16, 2014
Priority date	Oct 31, 2007
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

Disclosed is a process for producing spunbond fibers comprising melt blending a polypropylene having a melt flow rate (230/2.16) of from 10 to 30 dg/min with a peroxide visbreaker such that the resulting melt flow rate of the visbroken polypropylene is from 50 to 100 dg/min; melt extruding the visbroken polypropylene through a die block such that filaments of the visbroken polypropylene being produced are exposed to a cabin pressure of from 4500 to 7000 Pa; and forming fibers of from less than 6.0 denier. Nonwoven fabrics and multiple-layer structures can be made from the fibers described herein that are useful for filtering and absorption related articles.

First claim

The invention claimed is:

1. A process for producing spunbond fibers consisting essentially of:
providing a polypropylene having a melt flow rate (230/2.16) of from 10 to 30 dg/min;
melt blending the polypropylene with a visbreaking agent such that the resulting melt flow rate of the visbroken polypropylene is from 50 to 100 dg/min, wherein the visbroken polypropylene has a M z /M w from 2.0 to 2.8, and the visbroken polypropylene has an M w /M n of from 3.5 to 7.0;
melt extruding the visbroken polypropylene through a die block such that filaments of the visbroken polypropylene being produced are exposed to a cabin pressure of from 4500 to 7000 Pa, wherein the throughput of the visbroken polypropylene in forming filaments is greater than 200 kg/hour; and
forming fibers of from less than 6.00 denier;
wherein the pressure inside the die block ranges from 35 to 45 bar (3500 to 4500 kPa).

2. The process of claim 1 , wherein the fibers are further directed to a receiver mat to form a spunbond fabric.

3. The process of claim 1 , wherein the cabin pressure ranges from 4700 to 6500 Pa.

4. The process of claim 1 , wherein the visbroken polypropylene has an M z /M w of 2.0 to 2.54.

5. The process of claim 1 , wherein the visbroken polypropylene has an M w /M n of from 3.6 to 6.5.

6. The process of claim 1 , wherein the throughput of the visbroken polypropylene in forming filaments is within a range from 220 to 1000 kg/hour.

7. The process of claim 1 , wherein the pressure inside the die block ranges from 30 to 40% lower than the die pressure when a 30 to 40 dg/min (230/2.16) propylene homopolymer having an MWD of from 2.7 to 3.3 is formed into a spunbond fiber under the same die, throughput and melt temperature conditions.

8. The process of claim 1 , wherein the melt temperature of the die block ranges from 200 to 260° C.

9. The process of claim 1 , forming fibers of from less than 2.00 denier.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Ferry William M
• Richeson Galen C

Classifications

• D01D5/08

  Melt spinning methods {(D01D5/0023 takes precedence)} · CPC title

• Y10T442/681

  Spun-bonded nonwoven fabric · CPC title

• D10B2321/022

  polypropylene · CPC title

• D04H3/16

  with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion · CPC title

• D01D1/065 Primary

  Addition and mixing of substances to the spinning solution or to the melt; Homogenising · CPC title