Note: Descriptions are shown in the official language in which they were submitted.
~Z~90(~
This invention relates to a process for product
in a granular, water-s~7ellable cross linked acrylic co-
polymer, and its use. Particularly, this invention no-
fates to a process for producing a granular, water-s~el-
fable cross linked acrylic copolymer which has excellent
water sealability, shape retention (water insolubility)
and transparency, shows excellent performance in its use
as artificial soil in regard to water retention, root
holding property, air holding property and ornamental
property, and is particularly useful as artificial soil in
hydroponics; and to its use as artificial soil.
More specifically, this invention pertains to a
process for producing a granular, water-swellable cross-
linked acrylic copolymer, which comprises copolymerizing
in an aqueous medium in the presence of a radical polyp
merization initiator a monomeric mixture comprising (a) at
least one acrylic aside monomer selected from the group
consisting of acrylamide, methacrylamide and N-methyl
substitution products of these asides and (b) at least one
acrylic crosslinkable comonomer selected from the group
consisting of N,N'-alkylene- or arylene-bisacrylamides,
N,N'-alkylene-bismethacrylamides, alkylene-bisacrylates,
alkylene-bismethacrylates, alkaline glycol-bisacrylates,
polyalkylene glycol-bisacrylates, alkaline glycol-bis-
methacrylates, and polyalkylene glycol-bismethacrylates,
the proportion of the comonomer (b) being 0.01 to 5 moles
per 100 moles of the acrylic aside monomer (a), and form-
in a granular copolymer; and (i) drying the resulting
granular copolymer at a temperature of 105 to 150C, or
(ii) heat-treating the resulting granular copolymer in the
presence of moisture under substantially sealed conditions
at a temperature of 100 to 160C.
This invention also pertains to the use of the
1239~0
-- 2
resulting granular, water-swellable cross linked acrylic
copolymer as artificial toil, particularly for hydra-
ponies.
Granular water-swellable cross linked acrylic
copolymers derived from acrylic aside monomers and acrylic
crosslinkable comonomers have been used, for example, as
artificial soil, such as artificial soil in hydroponics, a
soil conditioner, etc. In any of these applications, the
copolymers are required to have good water sealability.
or use as artificial soil in hydroponics, they are also
required to have high transparency to provide ornamental
characteristics.
Japanese Laid-Open Patent Publication No.
145908/1981 plaid open on November 13, 1981) relates to a
water-exchangeable nontoxic polymeric material derived
from an acrylic aside monomer and an acrylic crosslinkable
comonomer and a process for its production. The polymeric
material is stated to be useful as artificial soil which,
for example, serves to make barren lands such as desert or
to stabilize soil used for concentrated cultivation, for
example soil in greenhouses and pots for flower and other
plants.
This Japanese patent document discloses a pro-
cuss for producing a water-exchangeable nontoxic water-
insoluble polymeric material by copolymerizing acrylamideand N,N'-methylene-bisacrylamide under controlled con-
dictions, which comprises (1) dissolving acrylamide and
N,N'-methylene-bisacrylamide together in water with the
maximum weight ratio of the monomers to water being kept
I at 2:8, (2) optionally adding an N-substituted acrylamide
monomer further so that the weight ratio of the monomers
to water does not exceed said maximum ratio, I adding at
least one finely pulverized polymerization initiator,
suspended and/or dissolved, while stirring the resulting
aqueous solution, (4) copolymerizing the monomers at a
temperature higher than 50C, (5) granulating the
~2~90~
-- 3
resulting gel and washing the granules to a maximum acryl-
aside monomer content of not more than 0.1% by weight
based on the weight of the final product, and (6) drying
the granules at a temperature lower than 100C to a
maximum moisture content of 12% by weight based on the
final product, and thus completely copolymerizing and
curing the granules. The weight ratio of the acrylamide
to N,N'-methylene-bisacrylamide exemplified is from 9:1 to
9 9 : 1 .
lot air drying at 95 + 5C is recommended in the
above patent document, but the patent document does not
refer to drying at more than 100C and is completely
silent on heat treatment in the presence of water under
substantially sealed conditions.
The water sealability of the granular, water-
syllable cross linked acrylic copolymer obtained by the
process of this Japanese patent document is not high
enough to be satisfactory, and is still desired to be
improved. Particularly, the product of this prior art does
not have fully satisfactory performance as artificial
soil, especially for hydroponics.
The present inventors made extensive invest-
gallons in order to provide a granular, water-swellable
cross linked acrylic copolymer derived from an acrylic
aside monomer and an acrylic crosslinkable comonomer which
is useful as artificial soil and can overcome the dip-
faculties of the prior acrylic copolymers discussed above.
These investigations have led to the discovery that a
granular, water-swellable cross linked acrylic copolymer
which is free from the aforesaid difficulties, has excel-
lent water-swellability, shape retention and transparency,
and shows excellent performance as artificial soil, en-
specially for hydroponics, with regard to water holding
property, root holding property, air holding property and
ornamental characteristics can be provided by Capella-
meriting a monomeric mixture comprising 100 moles of (a)
an acrylic aside monomer and 0.01 to 5 moles of (b) an
acrylic erosslinkable eomonomer in an aqueous medium in
the presence of a radical polymerization initiator, form-
in a granular product by, for example, granulating the
resulting eopolymer into a desired granular form after the
eopolymerization or by performing the eopolymerization
under such conditions as to form the desired granular
eopolymer, and thereafter either (i) drying the granules
at a temperature of 105 to 150C (under non-sealed
conditions), or (ii) heat-treating the granules in the
presence of moisture at 100 to 160C under substantially
sealed conditions and as desired, further drying the
product at a temperature of, for example, 40 to 150C
(under non-sealed conditions).
It is an object of this invention therefore to
provide a process for producing an improved granular,
water-swellable erosslinked acrylic eopolymer.
Another object of this invention is to provide
the use of the resulting granular, water-swellable cross-
linked acrylic copolymer as artificial soil.
The above and other objects and advantages of this invention will become apparent from the following
description.
According to the process of this invention, a
monomeric mixture composed of (a) at least one acrylic
aside monomer selected from the group consisting of
acrylamide, methacryliamide and N-methyl substitution
products of these asides and (b) at least one acrylic
Crosslinkable comonomer selected from the group consist-
in of N,~1'-alkylene-bis-acryl- or methacryl-amicies,
alkylene-bis-acrylates or methacrylates and (poly)alkylene
glycol-bis-acrylates or methacrylates is copolymerized in
an aqueous medium in the presence of a radical polymeric
ration initiator.
Specific examples of the monomer (A) include
aerylamide, methacrylamide and such N-methyl substitution
I
products thereof as N-methylacrylamide, N,N-diethylacryl-
aside, N-methylmethacrylamide and N,N-dimethylmethacryl-
aside. The use of acrylamide and/or methacrylamide is
preferred as the monomer (a).
Specific examples of the comonomer (b) include
N,N'-~Cl-C6)alkylene- or (C6)arylene-bisacryl- or bismuth-
acryl-amides such as N,N'-methylenebis(meth)acrylamide,
N,N'-ethylenebis(meth)acrylamide, N,N'-propylenebis(meth)-
acrylamide, N,N'-hexamethylenebis~meth)acrylamide and
lo N,N'-phenylenebis(meth)acrylamide; (C2-C6)alkylene-bis-
acrylates or bismethacrylates such as ethylenebis(meth)-
acrylate, propylenebis(meth)acrylate and hexamethylenebis-
(meth)acrylate; and polyalkylene glycol-bisacrylates or
bismethacrylates having a molecular weight of 214 to
5,000, such as diethylene glycol bis(meth)acrylate, in-
ethylene glycol bis(meth)acrylate and polyethylene glycol
bis(meth)acrylate.
Of these, N,N'-methylene-bis(meth)acrylamide,
N,N'-methylene-bisacrylate and N,N'-methylene-bismeth-
acrylate are preferred.
In the present invention, the aforesaid moo-
metric mixture may contain a minor amount of (c) an us-
saturated monomer copolymerizable with the monomer (a) and
the comonomer (by. Examples of the other monomer (c) are
acrylic acid, methacrylic acid, malefic acid, functional
derivatives of these acids such as their acid androids,
salts and esters (e.g., lower alkyd esters), vinyl
acetate, styrenes methylstyrene and vinyltoluene. The
monomeric units of this type may also be introduced by
other means than coplymerization, or example by hydra-
louses.
In order to impart protection from algae, mold-
profanes and coloration to the granular, water-swellable
Cross linked acrylic copolymer obtained in this invention,
it is possible to add (d) an unsaturated monomer come
potent, such as an anti-algal unsaturated monomer (e.g.,
owe
-- 6
a vinyl bond-containilng tria7ine-type derivative and
a vinyl bond containing organotin compound, a mold proof
unsaturated monomer or a coloring unsaturated monomer.
Specific examples of the monomer (d) include 4-(~-acryloyl-
5 N-ethyl)amino-6-isopropylamino-2-methylthio-s-triaamine,
4-(N-acryloyl-~-ethyl)amino-2-chloro-6-s-triazine,,
4-(N-acryloyl-N-ethyl)amino-2-chloro-6-isopropylamminors-
treason, chlorodibutyltin acrylate, tributyltin acrylate,
6-methylamino-5-[4-~-bromoacryloylamino-2-sulfo]azzoo
naphthalene-2-sulfonic acid, 4-(3-acryloylamino-phenyl-
amino)-l-amino-anthraquinone-2-sulfonic acid, l-acryloyl-
amino-4-phenylaminoanthraquinone, and 1-acryloylamino-4-
phenylamimidoanthraquinone.
In the monomeric mixture to be copolymerized by
the process of this invention, the proportion of the
acrylic crosslinkable comonomer (b) is 0.01 to 5 moles,
preferably 0.05 to 3 moles, per 100 moles of the acrylic
aside monomer (a). If the proportion of the comonomer by
is smaller than the lower limit specified above, the
resulting water-swellable cross linked acrylic copolymer
becomes too soft. When such a copolymer is used as anti-
filial soil particularly for hydroponics, its ability to
hold plants is reduced. On the other hand, too large a
proportion of the comonomer (b) beyond the upper limit
specified reduces the transparency of the resulting water-
syllable cross linked acrylic copolymer and degrades its
ornamental characteristics.
The amount of the monomer (c) which may further
be included in the monomeric mixture is up to 60 moles,
for example 0.01 to 60 moles, preferably up to I moles,
for example 1 to I moles, per 100 moles of the monomer
(a). The amount of the monomer (d) which may further be
included in the monomeric mixture is up to 15 moles, for
example 0.01 to 15 moles, preferably up to 10 moles, for
example 0.01 to 10 moles.
In the present invention, the monomeric mixture
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comprising the acrylic aside monomer (a) and the acrylic
crosslinkable monomer IBM an if required, the monomer (c)
and/or the monomer (d) is copolymerized in an aqueous
medium in the presence of a radical polymerization in-
shutter.
The radical polymerization initiator may be a
water-soluble radical polymerization initiator such as
ammonium per sulfate, potassium per sulfate and sodium
persulfateO Two or more of these initiators may be used
in combination. The amount of the radical polymerization
initiator may be properly selected. For example, it is
about 0.001 to about 10 moles, preferably about 0.01 to
about 5 moles, per 100 moles of the monomer (a). As
required, an amine may be used in combination with the
radical polymerization initiator in accordance with a
technique known Per so. Examples of such amine are
triethanolamine and 3-dimethylaminopropionitrile. The
amount of the amine is, for example, 0.1 to 30 moles per
mole of the radical polymerization initiator.
The copolymerization reaction may be carried out
while the monomeric mixture is in the form of an aqueous
solution, or while forming an aqueous dispersion by stir-
ring a mixture of an aqueous solution of the monomeric
mixture and a solvent inducing phase separation from the
aqueous solution under the polymerization conditions. An
oil-soluble polymerization initiator such as azobisiso-
butyronitrile or ensoul peroxide may also be used as the
polymerization initiator in the above process. The "co-
polymerization in an aqueous medium", as referred to in
the present invention, is meant to include copolymeri-
ration in the above-exemplified aqueous dispersion.
The amount of water may be properly selected in
performing the copolymerization reaction, and may be any
desired amount capable of forming an aqueous solution of
the monomeric mixture. For example, it is 100 to 5,000
parts by weight, preferably 200 to 5,000 parts by weight,
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-- 8 --
per 100 parts by weight of the monomeric mixture. The
polymerization temperature may be properly selected, and
is, for example, 10 to 150C, preferably 50 to 100C.
The polymerization time may be properly chosen, and is,
for example, 1 to 600 minutes, preferably 3 to 300
minutes.
In the process of this invention, granules in
the desired shape are formed by, for example, granulating
the resulting copolymer into the desired shape after the
copolymerization, or by performing the copolymerization
under such conditions as to form a copolymer of a desired
granular shape. The granules may be in the shape ox a
solid cylinder, a prism (a regular prism, a right prism, a
triangular prism, a tetragonal prism, a pentagonal prism,
a hexagonal prism, etc.), a cone, a pyramid, a sphere, a
hollow cylinder, or a hollow prism.
The granules may be formed by using suitable
methods which can give granules of the desired shapes.
Some of the examples are given below.
(1) method which comprises polymerizing a
starting aqueous solution containing the monomeric mixture
and the radical polymerization initiator by passing it
through a tube of a desired shape under heat, extruding
the resulting water-s~7ellable gel-like cross linked co-
polymer, and cutting the polymer with a cutter to give
granules having various prismatic shapes. The surface of
the cutter and the inside surface of the polymerization
tube may be coated with a fluorine-containing resin such
as polyfluoroethylene polymers in order to improve the
lubricity of the gel-like cross linked copolymer.
(2) A method which comprises polymerizing the
starting aqueous solution by passing it through the tube,
extruding the resulting water-swellable gel-like cross-
linked copolymer through a Michelle blade of the desired
shape to obtain prismatic granules, and cutting the
granules with a cutter to obtain granules of various
_ 9
prismatic shapes. The surface of the mesh-like blade and
the inside surface of the polymerization tube may be
coated as in (1).
(3) A method comprising polymerizing the start-
in aqueous solution in bulk, and cutting the resulting ingot to form granules of the desired shape.
(4) A method which comprises polymerizing the
starting aqueous solution into a plate form, and cutting
it by a mesh e blade or a cutter to obtain the desired
shape.
(5) A method which comprises polymerizing the
starting aqueous solution on a belt conveyor having a
polymerization mold of the desired shape.
(6) A method which comprises stirring a mixture
composed of the starting aqueous solution and a solvent
capable of inducing phase separation from the aqueous
solution under the polymerization conditions, thereby to
obtain nearly spherical granules. The shape and size of
the water-swellable gel-like cross linked copolymer may be
varied by changing the type and amount of the solvent, the
stirring conditions, the temperature, etc.
In addition, the resulting water-swellable
gel-like cross linked copolymer is pulverized to form a
powdery or granular polymer according to the purpose of
use.
The granular copolymer, as referred to in this
invention, is meant to denote all products obtained by the
techniques exemplified above.
In the present invention, the resulting granules
may be
(i) dried (under non-seale~l conditions) at a
temperature of 105 to 150C, or
(ii) heat-treated at 100 to 160C under sub Stan-
tidally sealed conditions in the presence of water. As
desired, the heat-treated granules may further be dried
(under non-sealed conditions) at a temperature of, for
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it I; ;
-- 10 --
example, 40 to 150C.
In the embodiment (i), it is desirable to in-
crease the conversion in the copolymerization reaction in
order to obtain a cross linked copolymer having excellent
S water sealability and transparency. Preferably, there is
used a copolymer obtained by performing the copolymeri-
ration until the polymerization conversion reaches pro-
fireball at least 80%, especially preferably at least 85%.
In the embodiment (i), the water-swellable
gel-like cross linked copolymer is cried at a temperature
of 105 to 150C, preferably 110 to 15Q C, more preferably
110 to 140C. If the drying temperature is too low
beyond the above-temperature range (for example, when it
is 100C or less), the water sealability of the polymer
is reduced. If it is too high, the transparency of the
polymer is very much reduced. Accordingly, the tempera-
lure specified above is employed.
The drying treatment may be carried out at a
temperature of 105 to 150C by any desired means capable
of producing a drying effect. For example, known drying
means such as hot air drying and infrared ray drying
may be properly carried out. The drying is carried out
under non-sealed conditions in which drying is effected.
In the embodiment (ii), the water-swellable
gel-like cross linked copolymer is heat-treated at a
temperature of 100 to 160C, preferably 110 to 150C,
under substantially sealed conditions in the presence of
moisture. If the heat-treatment in the presence of water
is carried out at a temperature lower than the above-
specified limit, no satisfactory improvement in water
sealability is obtained. If, on the other hand, the
temperature is higher than the upper limit specified, the
copolymer is degenerated considerably and becomes sunsuit-
able for use as artificial soil in hydroponics.
The heat-treatment in the presence of moisture
can be carried out by suitable means which do not produce
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a dry condition with a substantial loss of moisture. Some
examples are shown below.
(1) method which comprises heat-treating the
water-swellable gel-like cross linked copolymer in the
swollen state under substantially sealed conditions in a
container.
(2) A method which comprises partially dehydrate
in and drying the water-swellable gel-like cross linked
copolymer and thereafter heat-treating it under sub Stan-
tidally sealed conditions in a container.
(3) method which comprises completely Dodd-
rating and drying the water-swellable gel-like cross linked
copolymer to give a water-swellable cross linked copolymer,
adding water, and then heat-treating the copolymer under
substantially sealed conditions in a container.
In any of such methods, the heat-treatment may
be carried out under such conditions that moisture is not
lost from the vapor or liquid phase. According to the
methods (1) and (2), the gel-like cross linked copolymer
may be directly heat-treated because it contains water.
As a matter of course, the heat-treatment may be carried
out after adding water. According to the method (3),
water is adder to the water-swellable cross linked co-
polymer prior to heat-treatment. The amount of water to
be present may be at least about 0.1 part by weight, per
100 parts by weight of the water-swellable cross linked
copolymer in the dry state.
The heat-treatment may be carried out under such
substantially sealed conditions that moisture contained in
the water-swellable gel-like copolymer is not lost in
substantial amounts by evaporation, for example in a
sealed vessel such as a sealed tube or autoclave. At this
time, the heat-treament may also be carried out in such an
atmosphere as argon, helium, carbon dioxide gas, steam,
etc. The heat-treatment time can be properly selected,
and is, for example, about 3 to about 600 minutes,
~;390~
preferably about 10 to about 300 minutes.
In the heat-treatment method (2), the tempera-
lure at which the partial dehydration and drying is
carried out before the heat-treatment is not particularly
limited, and may, for example, be about 40 to about
150C, preferably 60 to 140C.
As required, the heat-treated water-swellable
cross linked polymer may be dried. The drying temperature
at this time is usually 40 to 150C, preferably 60 to
140C.
The water-swellable cross linked polymer obtained
by the process of this invention has excellent water
sealability, shape retention and transparency and can be
used in various applications in the shapes exemplified
hereinabove. Depending upon its end uses, it may be
pulverized in a powdery or granular form after the drying
treatment.
The water-swellable cross linked acrylic co-
polymer which can be produced as above has a water swell
lying ratio of usually at least 65, preferably 70 to ~00.
The water swelling ratio, as used herein, is determined as follows:-
A fixed weight owl g) of the dry copolymer is sampled, and immersed in deionized water at 2~C for 24
hours. Then, the copolymer is poured onto a wire gauze
having a size of 100 mesh to remove the excess of water.
Then, the weight (We g) of the swollen gel-like polymer
is measured. The water swelling ratio is calculated in
accordance with the following equation
W - W
We
The water-swellable cross linked acrylic Capella-
men in granular form obtained by the process of this
invention is especially useful as artificial soil in
agriculture and horticulture, and above all as artificial
1~9~0~
- 13 -
soil in hydroponics.
Thus, according to this invention, there is also
provided a method of hydroponically growing a plant, which
comprises growing the plant in artificial soil composed of
a granular, water-swellable cross linked acrylic copolymer,
said acrylic copolymer being obtained by copolymerizing in
an aqueous medium in the presence of a radical polymer
ration initiator a monomeric mixture comprising (a) at
least one acrylic aside monomer selected from the group
consisting of acrylamide, methacrylamide and N-methyl
substitution products of these asides and (b) at least one
acrylic crosslinkable comonomer selected from the group
consisting of N,N'-alkylene- or arylene-bisacrylamides,
N,N'-alkylene-bismethacrylamides, alkylene-bisacrylates,
alkylene-bismethacrylates, (poly)alkylene glycol-bis-
acrylates and (poly)alkylene glycol-bismethacrylates, the
proportion of the comonomer (b) being 0.01 to 5 moles per
100 moles of the acrylic aside monomer (a), and forming a
granular copolymer; and (i) drying the resulting granular
copolymer at a temperature of 105 to 150C, or (ii)
heat-treating the resulting granular copolymer in the
presence of moisture under substantially sealed conditions
at a temperature of 100 to 160C.
The artificial soil for hydroponics in accord-
ante with this invention is suitable for growing various plants, particularly ornamental plants, because it has
good transparency, air holding property, water holding
property and root holding property. Furthermore, since it
permits good observation of the state of growth of roots,
it is also suitable for growing plants in order to test an
observing germination and growth of plants, the growing of
roots, etc. Suitably, hydroponics on this artificial soil
may be practiced in transparent pots, planters and other
suitable receptacles made of glass, polystyrene, polyp
methyl methacrylate, polyphonies, etc.
The hydroponically technique itself is well known,
~,23900~
- 14 -
and may be practiced in this invention except that the
artificial soil of this invention is used. For example,
it is possible to sow seeds, plant bulbs and tubers, or
transplant seedlings or grow plants in the artificial soil
of this invention swollen with water. As required, water
used for this purpose may contain suitable amounts and
suitable concentrations of fertilizer components such as
N, PLY and K. For example, the Holland solution may be
dissolved in the water used. At times, a coloring agent
may be dissolved in water to provide a greater ornamental
effect.
The following examples illustrate the present
invention more specifically.
Examples 1 to 8
In each run, a uniform starving solution of the
composition shown in Table 1 was continuously fed into a
tubular polymerization device of Teflon having an inside
diameter of 7 mm and a length of 300 mm, and polymerized
at a temperature of 90C for a period of 8 minutes. The
resulting water-swollen gel-like cross linked copolymer in
the form of a strand having a diameter of 7 mm was con-
tenuously cut to a length of 7 mm. The pellets of the
copolymer were washed in flowing water for 8 hours to
remove the monomers remaining in the copolymer. The
washed pellets of the copolymer were dried for 8 hours in
a hot air dryer kept at each of the temperatures indicated
in Table 1. The physical properties of the resulting
semi-transparent poulticed water-swellable cross linked
copolymer are shown in Table 1.
The pellets of the copolymer were dipped in
water containing a diluted liquid fertilizer (Holland
solution) to obtain a transparent water-swollen gel-like
cross linked copolymer containing the fertilizer. The
swollen gel-like cross linked copolymer (400 ml) was put in
US a glass bowl with a diameter of 130 mm and a height of
140 mm, and about 10 cm tall seedlings of begonia and
l~?ff(;O
- 15 -
saintpaulia were transplanted in the swollen copolymer in
the bowl. They were grown in a well sunlit room while
occasionally supplying a diluted aqueous solution of the
liquid fertilizer. Four months later, these plants were
growing in good condition.
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-- 16 --
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Examples 9 to 16
In each run, a uniform starting solution of the
composition indicated in Table 2 was polymerized, washed
in flowing water for 8 hours, and dried for 8 hours in a
5 hot air dryer kept at each of the temperatures shown in
Table 2 in the same way as in Example 1. The physical
properties of the resulting semi-transparent poulticed
water-swellable cross linked polymer are summarized in
Table 2.
Examples 17 to 19
In each run, a uniform starting solution of the
composition shown in Table 3 was polymerized, washed in
flowing water for 8 hours, and dried at 160C for 8
hours in a hot air dryer in the same way as in Example 1.
The polymer, however, foamed in popcorn form. When imp
messed in water, the popcorn-like water-swe~lable cross-
linked polymer absorbed water and became a water-swollen
gel-like cross linked polymer. But this gel became whitely
turbid over a broad range, and contained many bubbles.
Its appearance was therefore markedly impaired. The water
swelling ratio of the water-swollen cross linked polymer is
shown in Table 3.
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- 20 -
Example I
crylamide (88 g), 3 g of acrylic acid and 2.0 g
of N,N-methylene-bisacrylamide were dissolved in 900 g of
water, and 0.1 g of ammonium per sulfate was dissolved in
it to form a uniform solution. The solution was continue
ouzel fed into a tubular polymerization device of Teflon
having an inside diameter of 7 mm and a length of 300 mm,
and polymerized at 90C for 10 minutes. The resulting
water-swollen gel-like cross linked polymer in the form of
a strand having a diameter of 7 mm was cut continuously to
a length of 7 mm. The resulting water-swollen gel-like
Cross linked polymer was washed in flowing water for 8
hours to remove the monomers remaining in the copolymer.
After washing, the water-swollen gel-like cross linked
15 polymer was dried at 125C for 15 hours in a hot air
dryer. The resulting semi-transparent poulticed water-
syllable cross linked polymer had a water swelling ratio
of 120.
Example 21
A uniform starting solution having the same come
position as in Example 20 was polymerized in the same way
as in Example 20, washed in flowing water for 8 hours, and
then dried at 60C in a hot air dryer. The resulting
semi-transparent poulticed water-swellable cross linked5 polymer had a water swelling ratio of 80.
Examples 22 to 24
In each run, a uniform starting solution of the
composition shown in Table 4 was continuously fed into a
tubular polymerization device of Teflon having an
inside diameter of 7 mm and a length of 300 mm, and polyp
merited at ~0C for 8 minutes. The resulting water-
swollen cross linked polymer in the form of a strand having
a diameter of 7 mm was continuously cut to a length of 7
mm. The resulting pellets of the water-swollen gel-like
cross linked copolymer were washed in flowing water for 8
hours to remove the monomers remaining in the water-
owe
- 21 -
swollen gel-like cross linked copolymer. After washing, 30
g of the water-swollen gel-like cross linked copolymer was
put in a stainless steel sealed tube having a capacity of
50 ml and heat-treated in an oil bath kept at each of the
temperatures shown in Table 4 for 5 hours. It was then
dried to a constant weight in a hot air dryer at 100C.
The physical properties of the resulting semi-transparent
poulticed water-swellable cross linked polymer are shown
in Table 4.
The pellets of the copolymer were dipped in
water containing a diluted liquid fertilizer (Holland
solution) to obtain a transparent water-swollen gel-like
cross linked copolymer containing the fertilizer. The
swollen gel-like cross linked copolymer (400 ml) was put in
a glass bowl with a diameter of 130 mm and a height of 140
mm, and about 10 cm tall seedlings of begonia and saint-
Paula were transplanted in the swollen copolymer in the
bowl. They were grown in a well sunlit room while ox-
casionally supplying a diluted aqueous solution of the
liquid fertilizer. your months later, these plants were
growing in good condition.
-- 22 --
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- I -
Example 25
uniform starting solution having the same
composition as in Example 10 was polymerized in the same
way as in Example 22, washed in flowing water for 8 hours,
and dried at 60C in a hot air dryer until its water
content became 100~ of its own weight. Thirty grams of
the resulting semi-transparent poulticed water-swollen
cross linked copolymer was put in a 50 ml stainless steel
sealed tube, and heat-treated in an oil bath at 140C
for 5 hours. It was then dried in a hot air dryer at
100 C until its weight became constant. The resulting
semi-transparent pullets water-swollen cross lined
copolymer had a density of 1.30 g/cm3 and a water swell
lying ratio of 121.
The pellets of the copolymer were dipped in
water containing a diluted liquid fertilizer (Holland
solution to obtain a transparent water-swollen gel-like
cross linked copolymer containing the fertilizer. The
swollen gel-like cross linked copolymer (400 ml) was put in
a glass bowl with a diameter of 130 mm and a height of 140
mm, and about 10 cm tall seedlings of begonia and saint-
Paula were transplanted in the swollen copolymer in the
bowl. They were grown in a well sunlit room while ox-
casionally supplying a diluted aqueous solution of the
liquid fertilizer. Four months later, these plants were
growing in good condition.
example 26
A uniform starting solution of the same come
position as in Example 22 was polymerized in the same way
as in example 22, and then washed in flowing water fox 8
hours. Thirty grams of the resulting water-swollen gel-
like cross linked copolymer was put in a 50 ml stainless
steel sealed tube, and heat-treated in an oil bath at
90C for 5 hours, followed by drying to a constant
weight in a hot air dryer at 100C. The resulting
semitransparent poulticed water-swellable cross linked
Jo.
- 24 -
copolymer had a density of 1.30 g/cm3 and a water swell
lying ratio of 35.
Example 27
uniform starting solution having the same
composition as in Example 22 was polymerized in the same
way as in Example 10, and washed in flowing water for 8
hours. Thirty grams of the resulting water-swollen vet-
like cross linked copolymer was put in a 50 ml stainless
steel sealed tube, and heat-treated in an oil bath at
180C for 5 hours. The polymer consequently became
water-soluble and could not be used for the intended
application.
Example 28
Acrylamide (88 g), 3 g of acrylic acid and 2.0 g
of ~l,N-methylene-bisacrylamide were dissolved in 900 g of
water and 0.1 9 of ammonium per sulfate was dissolved to
form a uniform solution. The solution was continuously
fed into a tubular polymerization device of Teflon
having an inside diameter of 7 mm and a length of 300 mm,
and polymerized at 90C for 8 minutes. The resulting
water-swollen gel-like cross linked copolymer in the form
of a strand having a diameter of 7 mm was continuously cut
to a length of 7 mm. The resulting water-swollen gel-like
cross linked copolymer was washed in flowing water for 8
hours to remove the monomers remaining in the copolymer.
After washing, 30 g of the water-swollen gel-like cross-
linked copolymer was put in a 50 ml stainless steel sealed
tube and heat-treated in an oil bath at 120C for 1 hour,
and then dried in a hot air dryer at 60C for 48 hours.
The resulting semitransparent poulticed water-
syllable cross linked polymer had a water swelling ratio
of 150.
Example 29
uniform starting solution of the same come
position as in Example 10 was polymerized in the same way
as in Example 10, washed in flowing water for hours, and
owe
dried in a hot air fryer at 60C for 48 hours. The
resulting semitransparent poulticed w~ter-swollen cross-
linked copolymer had a water swelling ratio of 80.
