Patent ID: 11913935
Assignee: LG CHEM, LTD.
Field: Measurement (Instruments)
Classification: CPC D  G | IPC D  G

Claim 0:
1. A method for evaluating a loft property of a propylene non-woven fabric prepared by a melt blown process of a combination of a first polypropylene resin and a second polypropylene resin, the method comprising steps of:
preparing a first sample of the first polypropylene resin and preparing a second sample of the second polypropylene resin, respectively;
deriving a residual stress ratio of the first sample and a residual stress ratio of the second sample, respectively, by the steps of:
applying 150 to 250% strain to each sample;
a first time (Time S1) after applying the strain, measuring a first residual stress (Stress S1);
a second time (Time S2) after applying the strain, measuring a second residual stress (Stress S2); and
deriving a residual stress ratio represented by Equation 1:

Residual stress ratio=Stress S2/Stress S1  [Equation 1]

in Equation 1,
Stress S1 is the first residual stress measured after the first time (Time S1),
Stress S2 is the second residual stress measured after the second time (Time S2), and
Time S2>Time S1,

comparing the residual stress ratio of the first sample and the residual stress ratio of the second sample, and
determining that the loft property of the propylene non-woven fabric is appropriate if the residual stress ratio of the first sample is at least 10 times the residual stress ratio of the second sample.