An aqueous emulsion may include an ethylene-vinyl alcohol copolymer (A) as a dispersant and a polymer (B) which contains an ethylenically unsaturated monomer unit as a dispersoid, wherein the ethylene-vinyl alcohol copolymer (A) has an ethylene unit content of 1 mol % or more and less than 20 mol %; and a crystallinity in water at 30° C. (Cw (30° C.)) and a crystallinity in water at 70° C. (Cw (70° C.)) as determined by pulse NMR satisfying formula (I). Such aqueous emulsions can form fewer aggregates and exhibit excellent water-resistant adhesiveness and excellent film formability.

An aqueous emulsion may include an ethylene-vinyl alcohol copolymer (A) as a dispersant and a polymer (B) which contains an ethylenically unsaturated monomer unit as a dispersoid, wherein the ethylene-vinyl alcohol copolymer (A) has an ethylene unit content of 1 mol % or more and less than 20 mol %; and a crystallinity in water at 30° C. (Cw (30° C.)) and a crystallinity in water at 70° C. (Cw (70° C.)) as determined by pulse NMR satisfying formula (I). Such aqueous emulsions can form fewer aggregates and exhibit excellent water-resistant adhesiveness and excellent film formability.

According to the method for preparation of a super absorbent polymer according to of the present disclosure, fine particles present in the prepared super absorbent polymer are removed, thereby solving a dispersion problem of the fine particles and a problem of reduction in the physical properties of the super absorbent polymer.

The present invention relates to a super absorbent polymer having not only excellent absorption rate and absorbency under load but also excellent rewetting properties, and a method for preparing the same.

An ethylene-vinyl alcohol copolymer may have an ethylene unit content of 1 mol % or more and less than 15 mol %, a saponification degree of 85 mol % or more and less than 99.9 mol %, and a viscosity-average degree of polymerization of 200 or more and less than 3000. The copolymer may contain a molecule containing a structure (I)

##STR00001##

Y being H or —CH.sub.3, at an end; and a molecule containing a structure (II)

##STR00002##

Z being H or —CH.sub.3, at an end, a total content of the structure (I) and the structure (II) in all monomer units is 0.001 mol % or more and less than 0.1 mol %, and a molar ratio R [I/(I+II)] of the structure (I) to the total of the structure (I) and the structure (II) satisfies formula (1):

[00001]$\begin{array}{cc}R<0.92-\mathrm{Et}/100,& \left(1\right)\end{array}$

Et being ethylene unit content (mol %).

An ethylene-vinyl alcohol copolymer may have an ethylene unit content of 1 mol % or more and less than 15 mol %, a saponification degree of 85 mol % or more and less than 99.9 mol %, and a viscosity-average degree of polymerization of 200 or more and less than 3000. The copolymer may contain a molecule containing a structure (I)

##STR00001##

Y being H or —CH.sub.3, at an end; and a molecule containing a structure (II)

##STR00002##

Z being H or —CH.sub.3, at an end, a total content of the structure (I) and the structure (II) in all monomer units is 0.001 mol % or more and less than 0.1 mol %, and a molar ratio R [I/(I+II)] of the structure (I) to the total of the structure (I) and the structure (II) satisfies formula (1):

[00001]$\begin{array}{cc}R<0.92-\mathrm{Et}/100,& \left(1\right)\end{array}$

Et being ethylene unit content (mol %).

The production method includes a drying step of drying a particulate crosslinked hydrogel polymer obtained by polymerizing a monomer, which is a material of a water-absorbent resin, using a heating device to obtain dried particles. The heating device includes: a rotary container that contains the particulate crosslinked hydrogel polymer therein and rotates; and a plurality of heating tubes that are located within the rotary container, extend in an axial direction of the rotary container, and rotate together with the rotary container. A gel temperature of the particulate crosslinked hydrogel polymer to be subjected to the drying step, the gel temperature being measured by a contact thermometer, is not lower than 50° C.

According to one or more embodiments disclosed herein, the amount of one or more contaminants in an initial ultra high molecular weight polyethylene composition may be reduced by a method including contacting the initial ultra high molecular weight polyethylene composition with an acid to form a processed ultra high molecular weight polyethylene composition. The initial ultra high molecular weight polyethylene composition may include at least 0.02 wt. % of one or more contaminants. The contacting of the acid with the initial ultra high molecular weight polyethylene composition may be for a time, at a pressure, and at a temperature sufficient to reduce the amount of the one or more contaminants in the initial ultra high molecular weight polyethylene.

According to one or more embodiments disclosed herein, the amount of one or more contaminants in an initial ultra high molecular weight polyethylene composition may be reduced by a method including contacting the initial ultra high molecular weight polyethylene composition with an acid to form a processed ultra high molecular weight polyethylene composition. The initial ultra high molecular weight polyethylene composition may include at least 0.02 wt. % of one or more contaminants. The contacting of the acid with the initial ultra high molecular weight polyethylene composition may be for a time, at a pressure, and at a temperature sufficient to reduce the amount of the one or more contaminants in the initial ultra high molecular weight polyethylene.

A water-absorbent resin (21) has a shape in which a plurality of particles (40) having a substantially spherical shape is connected in a chain shape.