Super absorbent polymer
A super absorbent polymer, where a TD-NMR analysis result after swelling the super absorbent polymer with D 2 O satisfies Equation 1: N t=0.1 (%)≤50(%), where N t=0.1 represents a normalized intensity measured at a signal acquisition time of 0.1 ms.
1 . A polyacrylic acid (salt)-based super absorbent polymer,
wherein a TD-NMR analysis result after swelling the polyacrylic acid (salt)-based super absorbent polymer with D 2 O satisfies Equation 1, and
wherein the polyacrylic acid (salt)-based super absorbent polymer has an average convexity value of 0.94 or less for all particles, calculated using Equation 2:
N t=0.1 (%)≤50(%) [Equation 1]
M c =L s /L [Equation 2]
in Equation 1 and Equation 2,
N t=0.1 represents a normalized intensity measured at a signal acquisition time of 0.1 ms,
M c represents convexity,
L s represents a length of a perimeter of a polygon of minimal perimeter that surrounds a two-dimensional image of a three-dimensional particle to be measured, and
L represents an actual perimeter length of the two-dimensional image of the three-dimensional particle to be measured.
2 . The polyacrylic acid (salt)-based super absorbent polymer of claim 1 , wherein the TD-NMR analysis result after swelling the polyacrylic acid (salt)-based super absorbent polymer with D 2 O shows that N t=0.1 (%) is 45 (%) or more.
3 . The polyacrylic acid (salt)-based super absorbent polymer of claim 1 , wherein the polyacrylic acid (salt)-based super absorbent polymer has an extractable component content of 10 wt % or less based on the total weight of the polyacrylic acid (salt)-based super absorbent polymer as measured after being freely swollen in water having an electrical conductivity of 100 to 130 μS/cm for 30 minutes.
4 . The polyacrylic acid (salt)-based super absorbent polymer of claim 1 , wherein the polyacrylic acid (salt)-based super absorbent polymer has an extractable component content of 17 wt % or less based on the total weight of the polyacrylic acid (salt)-based super absorbent polymer as measured after being freely swollen in water having an electrical conductivity of 100 to 130 μS/cm for 3 hours.
5 . The polyacrylic acid (salt)-based super absorbent polymer of claim 1 , wherein the polyacrylic acid (salt)-based super absorbent polymer has an absorbency under pressure (AUP) of 28 g/g or more measured under 0.3 psi according to EDANA method WSP 242.3.
6 . The polyacrylic acid (salt)-based super absorbent polymer of claim 1 , wherein the polyacrylic acid (salt)-based super absorbent polymer has a centrifuge retention capacity (CRC) of 33 g/g or more measured according to EDANA method WSP 241.3.
7 . The polyacrylic acid (salt)-based super absorbent polymer of claim 1 , wherein the polyacrylic acid (salt)-based super absorbent polymer has an effective absorption capacity (EFFC) of 30 g/g or more, calculated by Equation 3:
EFFC=( CRC+AUP )/2 [Equation 3]
in Equation 3,
CRC represents a centrifuge retention capacity (units: g/g) measured according to EDANA method WSP 241.3, and
AUP represents an absorbency under pressure (units: g/g) measured under 0.3 psi according to EDANA method WSP 242.3.
8 . The polyacrylic acid (salt)-based super absorbent polymer of claim 1 , wherein the polyacrylic acid (salt)-based super absorbent polymer has an absorption rate (vortex time) of 40 seconds or less measured by a vortex measurement method at 24.0° C.
9 . The polyacrylic acid (salt)-based super absorbent polymer of claim 1 , wherein when the polyacrylic acid (salt)-based super absorbent polymer is swelled in water having an electrical conductivity value of 100 to 130 μS/cm for 1 minute, a maximum capacity of water that the polyacrylic acid (salt)-based super absorbent polymer holds (free swelling capacity) is 170 g/g or more.
10 . The polyacrylic acid (salt)-based super absorbent polymer of claim 1 , wherein the polyacrylic acid (salt)-based super absorbent polymer has a liquid permeability of 65 ml or more, calculated by Equation 4:
Perm=[20 mL/ T 1 (sec)]×60 sec [Equation 4]
in Equation 4,
Perm represents liquid permeability, and
T1 represents the time (seconds) taken for 20 mL of saline to pass through the swollen super absorbent polymer under a pressure of 0.3 psi after placing 0.2 g of a super absorbent polymer in a cylinder, pouring saline (0.9 wt % sodium chloride aqueous solution) so that the super absorbent polymer is completely submerged, and allowing the polyacrylic acid (salt)-based super absorbent polymer to swell for 30 minutes.