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US 6,669,888 B2Granted
Process of making polypropylene fibers
OwnerPyung Yul Park, Won Jun Cheyinventors
Life of this patent
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Abstract
Process of making polypropylene fibers obtained from an isotactic polypropylene homopolymer with an isotactic index of 90-99%, through melt-spinning or through drawing after melt-spinning, and shows two differential scanning calorimeter (DSC) endothermic peaks between 155 and 170 ° C. When being thermally bonded with each other, the fibers are made into non-woven fabrics which have excellent strength in addition to being soft. A high quality of the non-woven fabrics can be produced in a high speed carding machine with high yields.
Claims9
A method for preparing polypropylene fibers, comprising the steps of:
- (a) melting an isotactic polypropylene homopolymer with an isotactic index of 90-99%, a melting index (MIa) of 10.0-40.0 and a polydispersity index (PIa) of 2.5-6.0 to give a molten polymer which has a melt index (MIb) with the ratio of MIb/MIa ranging from 1.01 to 1.50 and a polydispersity index (PIb) narrower by 10% or less than the PIa;
- (b) spinning the molten polymer to produce fibers with a melting index (MIc) of 16.5-80.0 and a polydispersity index (PIc) narrower by 20% or less than the PIa, the ratio of MIc/MIa ranging from 1.65 to 7.50;
- and
- (c) optionally drawing the fibers.
1 more element
Dependencies are inferred from the claim text.