【TECHNICAL FIELD】
Cross-reference to Related Application(s)
This application claims the benefit of Korean Patent Application No. 10-
2021-0079644 filed on June 18, 2021, Korean Patent Application No. 10-2021-
0080343 filed on June 21, 2021, and Korean Patent Application No. 10-2022-
10 0074623 filed on June 20, 2022 with the Korean Intellectual Property Office,
the disclosures of which are herein incorporated by reference in their entirety.
This invention relates to a continuous polymerization reactor for super
absorbent polymer and a continuous polymerization reaction system comprising
the same, and more specifically, to a continuous polymerization reactor for
15 super absorbent polymer that can improve productivity and has high property
reproducibility, and a continuous polymerization reaction system comprising the
same.
【BACKGROUND】
Super absorbent polymer (SAP) is polymer material in the form of white
20 powder prepared by reacting acrylic acid with caustic soda, and it can absorb
moisture of about five hundred to thousand times of its own weight. The super
2
absorbent polymer is synthetic polymer material that is transformed to a jellylike form, if it absorbs water, and can store water without discharging, even
if a certain degree of pressure is applied from the outside.
Super absorbent polymer molecules have a network structure, and due to
5 many pores between the molecules, easily absorb water. Due to concentration
difference between ions in the super absorbent polymer and water, water moves
inside super absorbent polymer (by osmosis). If water molecules are introduced
inside super absorbent polymer, anions fixed inside try to occupy a specific
space by repulsive force, and thus, the space of polymer chains expands and
10 more water can be absorbed (electrostatic repulsion).
Such super absorbent polymer began to be commercialized as sanitary items,
and currently, is being widely used as water-holding material for soil, water
stop material for civil engineering and architecture, sheets for raising
seedling, freshness preservatives in the field of food circulation, fomentation
15 material, and the like, besides hygiene products such as paper diapers for
children, and the like.
Super absorbent polymer is marketed as powder products after drying and
grinding hydrogel or hydrogel polymer obtained through a polymerization reaction
in a polymerization reactor.
20 According to the prior art, hydrogel or hydrogel polymer was obtained
using a batch polymerization reactor. However, using the batch polymerization
reactor, it takes a substantial amount of time until the polymerization reaction
3
is completed after introducing a monomer composition, so as to obtain hydrogel
or hydrogel polymer. Thus, it was difficult to obtain a sufficient output with
the batch polymerization reactor.
In order to overcome such an insufficient output, plural batch
5 polymerization reactors may be used, but in this case, a larger space is required
to install plural polymerization reactors, and property difference may be
generated between hydrogels or hydrogel polymers obtained in each batch
polymerization reactor.
The background part has been described for better understanding of the
10 background of the invention, and may comprise information other than prior art,
already known to an ordinary skilled person in the art.
【DETAILED DESCRIPTION OF THE INVENTION】
【Technical Problem】
It is an object of the invention to provide a continuous polymerization
15 reactor for super absorbent polymer in which introduction of a monomer
composition and discharge of produced hydrogel or hydrogel polymer are
simultaneously conducted, thereby improving productivity and exhibiting high
property reproducibility, and a continuous polymerization reaction system
comprising the same.
20 【Technical Solution】
A continuous polymerization reactor for super absorbent polymer according
to an embodiment of the invention may include: a cylindrical body; a discharge
4
part with a diameter decreasing downward, positioned at a lower part the body;
an inlet positioned at an upper part of and connected to the body, into which
a monomer composition is introduced; an outlet positioned at a lower part of
the discharge part, from which hydrogel polymer is discharged; and a discharge
5 valve for opening or closing the outlet, wherein a ratio (H1/D1) of a sum (H1)
of a height of the body and a height of the discharge part to a diameter (D1)
of the body may be 2 ~ 4.
The monomer composition may be continuously introduced into the inlet
with a predetermined flow rate, and the discharge valve may control an open
10 rate of the outlet such that hydrogel polymer may be continuously discharged
from the outlet with the same flow rate as the predetermined flow rate.
The discharge valve may close the outlet, and open the outlet if a
predetermined time passes from a time when the final monomer composition begins
to be introduced, or a predetermined volume of the final monomer composition is
15 introduced.
A continuous polymerization reaction system according to another
embodiment of the invention may include: a first vessel in which water soluble
ethylenically unsaturated monomers having acid groups, a solvent, and an
internal crosslinking agent are stored; a second vessel in which a part of a
20 polymerization initiator is stored; a third vessel in which the other part of
the polymerization initiator is stored; a continuous polymerization reactor
including an inlet positioned at an upper part of the continuous polymerization
5
reactor, into which a monomer composition including the water soluble
ethylenically unsaturated monomers having acid groups, the solvent, the internal
crosslinking agent and the polymerization initiator is introduced, and an outlet
positioned at a lower part of the continuous polymerization reactor, from which
5 hydrogel polymer formed by polymerization of the monomer composition is
discharged; a feed pipe connected to the inlet so as to introduce the final
monomer composition; a first feed valve for selectively connecting the first
vessel with the feed pipe; a second feed valve for selectively connecting the
second vessel with the feed pipe; a third feed valve for selectively connecting
10 the third vessel with the feed pipe; a discharge valve for opening or closing
the outlet; and a controller for controlling the operations of the first, second,
and third feed valves and the discharge valve; wherein the controller may
control the first, second, and third feed valves such that the final monomer
composition may be continuously introduced through the inlet with a
15 predetermined flow rate, and control the discharge valve such that the hydrogel
polymer may be continuously discharged with the same flow rate as the
predetermined flow rate.