【TITLE OF THE INVENTION】
SUPER ABSORBENT POLYMER AND PREPARATION METHOD
THEREOF
【TECHNICAL FIELD】
5 Cross-reference to Related Application
This application claims the benefit of Korean Patent Applications No. 10-
2020-0178431 filed on December 18, 2020 and No. 10-2021-0180490 filed on
December 16, 2021 with the Korean Intellectual Property Office, the disclosures
of which are incorporated herein by reference in their entirety.
10 The present disclosure relates to a super absorbent polymer and a
method for preparing the same. More specifically, it relates to a super
absorbent polymer having an excellent absorption rate and absorption
performance together with a high aspect ratio, and a method for preparing the
super absorbent polymer.
15 【BACKGROUND OF ART】
A super absorbent polymer (SAP) is a type of synthetic polymeric
material capable of absorbing 500 to 1000 times its own weight of moisture.
Various manufacturers have denominated it with different names, such as SAM
(Super Absorbency Material), AGM (Absorbent Gel Material), and the like.
20 Such super absorbent polymers started to be practically applied in sanitary
products, and they are now being widely used not only for hygiene products, but
also for water retaining soil products for gardening, water stop materials for the
civil engineering and construction, sheets for raising seedling, fresh-keeping
2
agents for food distribution fields, materials for poultices, or the like.
These super absorbent polymers have been widely used in the field of
hygienic materials such as diapers or sanitary napkins. In such hygienic
materials, the super absorbent polymer is generally contained in a state of
5 being spread in the pulp. In recent years, however, continuous efforts have
been made to provide hygienic materials such as diapers having a thinner
thickness. As a part of such efforts, the development of so-called pulpless
diapers and the like in which the pulp content is reduced or pulp is not used at
all is being actively advanced.

【CLAIMS】
【Claim 1】
A super absorbent polymer, comprising
a powder-type base resin comprising a cross-linked polymer of an
5 acrylic acid-based monomer having at least partially neutralized acidic groups
and an internal cross-linking agent; and
a surface cross-linked layer formed by further cross-linking the crosslinked polymer using a surface cross-linking agent on the base resin,
wherein the super absorbent polymer satisfies the following properties of
10 ⅰ) an average value of an aspect ratio (A/R), which is a ratio of the
shortest diameter of a particle to the longest diameter of the particle measured
for particles having a particle diameter of 300 ㎛ to 600 ㎛, is 0.75 or more,
and an average value of convexity calculated by the following Equation 1 is 0.9
or less, and
15 ⅱ) a vortex time at 24.0 ℃ is 60 seconds or less:
[Equation 1]
Convexity = convex hull perimeter/actual particle perimeter
in Equation 1,
the convex hull perimeter is a length of an elastic band when it is
20 assumed that an image obtained by capturing a 3D image of a 3D particle to be
measured as a 2D image is surrounded by an imaginary elastic band extending
around the outline, and
the actual particle perimeter is an actual perimeter of an image obtained
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by capturing a 3D image of a 3D particle to be measured as a 2D image.
【Claim 2】
The super absorbent polymer of Claim 1,
5 wherein the super absorbent polymer has centrifuge retention capacity
(CRC) measured according to the EDANA WSP 241.3 of 27 g/g or more, and
absorbency under pressure (AUP) at 0.7 psi measured according to the EDANA
WSP 242.3 of 23.5 g/g or more.
10 【Claim 3】
The super absorbent polymer of Claim 1,
wherein the super absorbent polymer has a plurality of pores, and the
plurality of pores have an average diameter of 10 ㎛ to 400 ㎛.
15 【Claim 4】
The super absorbent polymer of Claim 1,
wherein the super absorbent polymer comprises hydrophobic particles
having an average particle diameter of 0.2 ㎛ to 50 ㎛.
20 【Claim 5】
The super absorbent polymer of Claim 4,
wherein the hydrophobic particles are at least one selected from the
group consisting of hydrophobic silica, a metal salt of a C7 to C24 fatty acid,
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and hydrophobic organic particles.