Method for metered supply of material, apparatus therefor, and method for production of hydrophilic polymer by use thereof

A method for metered supply of a delivered material to the next step, which method is characterized by regulating the thickness of the material on a conveyor before the material in the process of transfer on the conveyor from the incoming end thereof to the outgoing end thereof reaches the outgoing end, removing portions of a prescribed amount one at a time from the upper side part of the material by means of a scraping member adapted to cut into the upper side part of the material causing the removed portions of the upper side part of the material to be discharged past the outgoing end of the conveyor by means of the scraping member and, at the same time, causing the lower side part of the material discharged into by the scraping member to be discharged past the outgoing end by means of the conveyor, and an apparatus therefor.

FIELD OF THE INVENTION 
This invention relates to a method for metering the supply of a material, 
an apparatus for executing the method, and a method for the production of 
a hydrophilic polymer by the use of the apparatus. More particularly, this 
invention relates to a method for effecting metered supply of a wet 
material such as a hydrated gel substance, an apparatus for executing the 
method, and a method for efficient production of a hydrophilic polymer by 
the use of the apparatus. 
BACKGROUND OF ART 
For metered supply of a powdery substance or a granular substance, a belt 
conveyor, for example, has been used. The metered supply of a powdery 
substance or a granular substance by the use of a belt conveyor is 
accomplished by installing a switching gate or a roller over the conveyor 
thereby setting the thickness of the layer of the powdery or granular 
substance being forwarded on the conveyor at a prescribed value. When the 
conventional belt conveyor of the type described above is used for the 
purpose of transferring a viscous wet material such as a hydrated gel of 
hydrophilic polymer, such as absorbent resin, it is difficult to attain 
metered conveyance or supply of the wet material. 
The gate or roller disposed above the belt conveyor is actuated while the 
hydrated gel of absorbent resin delivered to the incoming end of the belt 
conveyor is in the process of transfer in the direction of the outgoing 
end the thickness of the layer of the hydrated gel of absorbent resin on 
the conveyor is regulated to a fixed value. Since the hydrated gel 
possesses viscosity, it is destined to gain in bulk density when it is 
compacted under the pressure exerted thereon in the region of the gate. 
Once this increase of bulk density occurs, the metered supply of the 
hydrated gel can no longer be obtained with high accuracy because the 
hydrated gel being transferred in the form of a layer of a fixed thickness 
from the outgoing end of the belt conveyor to the next step of drying has 
undergone changes in specific gravity and volumetric ratio from the 
initial state. Further, since the increased bulk density results in 
degrading the permeability of the hydrated gel to the air, the hot air is 
incapable of permeating into the interior of the layer of hydrated gel and 
fulfilling a continuous drying work throughout the entire volume of the 
layer of hydrated gel and consequently part of the layer of hydrated gel 
remains undried. 
Particularly for the purpose of drying a viscous material such as, for 
example, a wetted material, an aerating band type drier incorporating 
therein a band conveyor may be used. When this drier is used for drying 
the aforementioned hydrated gel, which has been compacted by pressure and 
consequently degraded in permeability to the air, the hot air is not 
sufficiently passed through the layer of the hydrated gel and the interior 
of the layer of the hydrated gel is dried very poorly. Thus, the layer of 
the hydrated gel reaching the outlet part of the drier inevitably contains 
an undried part. In the next step of pulverization, the undried part of 
the hydrated gel escapes pulverization and consequently adheres to and 
clogs the apparatus even to the extent of not only interfering with the 
work of continuous drying but also causing breakage of the apparatus in an 
extreme case. 
Particularly when the hydrated gel of hydrophilic polymers such as 
absorbent resin is obtained by polymerizing a monomer component containing 
50 to 100% by weight of acrylic acid (or a salt thereof), the disadvantage 
described above becomes all the more conspicuous because the viscosity 
exhibited independently or mutually by the individual particles of the gel 
is very high. 
This invention has been produced by the urge to fulfill the imperfect prior 
art described above. When a material delivered to the incoming end of a 
conveyor is advanced in a large heap on the conveyor, given a fixed 
thickness by the use of a gate and then transferred in a prescribed rate 
to the next step, it must be released in a loose state to the next step 
even if the material is a wet substance. When the wet material in the 
process of transfer toward the outgoing end of the conveyor is given a 
small thickness by the gate, the wet material slips on the upper surface 
of the conveyor and cannot be effectively transferred by the conveyor. 
When the wet material is given a sufficiently large thickness by the gate 
so as to avoid the phenomenon of slippage, it is not released in a loose 
state from the outgoing end of the conveyor. When the layer of the wet 
material is set at the aforementioned sufficiently large thickness by 
means of the gate, the bulk density of the wet material is increased 
throughout the entire width extent of the thickness. By causing the upper 
side part of the layer of the wet material to be scraped off with a 
scraping member and, meanwhile, allowing the lower side part thereof not 
discharged by the scraping member to be released from the outgoing end of 
the conveyor, the wet material can be continuously conveyed to the next 
step without being wholly compacted by pressure. 
An object of this invention, therefore, is to provide a method for metering 
the supply of a material which permits therefor material to be transferred 
in a prescribed rate with high accuracy to the next step and an apparatus 
to be used therefor. 
Another object of this invention is to provide a method for the efficient 
production of a hydrophilic polymer by causing a hydrated gel of 
hydrophilic polymer obtained by batch polymerization to be delivered in a 
prescribed rate with high accuracy into a drier and dried therein with 
high efficiency. 
SUMMARY OF THE INVENTION 
The objects described above are accomplished by a method for metering the 
supply of a delivered material to the next step, which method is 
characterized by regulating the thickness of the material on a conveyor 
before the material in the process of transfer on the conveyor from the 
incoming end thereof to the outgoing end thereof reaches the outgoing end, 
removing portions of a prescribed amount one at a time from the upper side 
part of the material by means of a scraping member adapted to cut into the 
upper side part of the material causing the removed portions of the upper 
side part of the material to be discharged past the outgoing end of the 
conveyor by means of the scraping member and, at the same time, causing 
the lower side part of the material not discharged by the scraping member 
to be discharged past the outgoing end by means of the conveyor. 
The aforementioned objects are also accomplished by an apparatus for 
metering the supply of a delivered material to the next step, which 
apparatus is characterized by having a conveyor interposed between the 
incoming end and the outgoing end of the material as directed toward the 
outgoing end, having disposed above the outgoing end scraping means fitted 
with a scraping member adapted to cut into the upper side part of the 
material reaching the outgoing end causing the scraping member to remove 
portions from the upper side part of the material reaching the outgoing 
end and discharge the removed portions past the outgoing end and, at the 
same time, causing the conveyor to discharge past the outgoing end the 
lower side part of the material not discharged by the scraping member. 
The objects described above are further accomplished by a method for the 
production of a hydrophilic polymer, which comprises metering the supply 
of the finely divided hydrated gel polymer obtained by batch 
polymerization to a drying device by the use of an apparatus for metering 
having a conveyor interposed between the incoming end and the outgoing end 
of the material as directed toward the outgoing end, having disposed above 
the outgoing end scraping means fitted with a scraping member adapted to 
cut into the upper side part of the material reaching the outgoing end 
causing the scraping member to remove portions from the upper side part of 
the material reaching the outgoing end, discharging the removed portions 
past the outgoing end and, at the same time, causing the conveyor to 
discharge past the outgoing end the lower side part of the material not 
discharged by the scraping member, and allowing the hydrated gel polymer 
to be dried with the drying means device.

BEST MODE FOR CARRYING OUT THE INVENTION 
In this invention, the material placed on the conveyor has its thickness 
regulated to a prescribed value while in the process of being transferred 
by the conveyor from the incoming end to the outgoing end thereof. This 
thickness is set at a value such that the phenomenon of slippage will not 
occur between the material and the conveyor. At this time, the material 
assumes a compacted state throughout the entirety of its thickness. The 
upper side part of the layer of the material which has gained in bulk 
density owing to the compaction is loosed by the scraping member and 
discharged in the loose state. Because of the removal of the upper side 
part of the layer of the material by the action of the scraping member, 
the lower side part thereof not discharged by the scraper discharged from 
the conveyor has a small thickness and a proportionately weak binding 
force and, therefore, assumes a similarly loose state at the time of its 
discharge from the conveyor. As the result, the material is transferred 
uninterruptedly to the next step. Thus, the supply of the material can be 
continuously carried out with high accuracy. 
Although the material thus discharged is sometimes packed and shipped as a 
product, it is usually charged to the following steps such as drying, 
secondary working, etc. In such case, the material discharged by the 
above-mentioned method for metered supply is supplied to the following 
step by another conveyor (hereinafter referred to "second conveyor"). The 
second conveyor is positioned at the same level of the above mentioned 
conveyor (hereinafter referred to "first conveyor") or at lower level of 
the first conveyor. When the second conveyor is positioned at the same 
level of the first conveyor, the conveying velocity of the second conveyor 
is preferable higher than that of the first conveyor. By setting higher 
velocity of the second conveyor, the material positioned at the lower part 
not discharged by the scraper provided with the conveying end of the first 
conveyor becomes the state that the material is loosened and the capacity 
for metered supply increases. On the other hand, when the second conveyor 
is positioned at the lower position of the first conveyor, the material 
positioned at the lower part not discharged by the scraper provided with 
the conveying end of the first conveyor becomes the state that the 
material is loosened by dropping from the conveying end of the first 
conveyor and is charged to the second conveyor. Therefore, the material at 
upper portion which is discharged by the scraper provided with the 
conveying end of the first conveyor and the material at lower portion 
which is not discharged by the scraper become loosened at the same time. 
Further, when the second conveyor is positioned at a lower position than 
the first conveyor, the second conveyor preferably has a higher velocity 
than the first conveyor in order to increase the capacity of the metered 
supply. 
The apparatus of this invention for metering the supply of a material is 
enabled substantially to accomplish the objects of the invention by 
satisfying exclusively the requirements for construction described above. 
When the second conveyor is positioned lower than the first conveyor, 
depending on the amount of the material to be delivered to the incoming 
end of the conveyor, for example, there is the possibility that the 
material will fall off the outgoing end of the first conveyor after the 
pattern of an avalanche so violent as to disrupt the metering property of 
the apparatus. The first conveyor, therefore, is desired to be provided at 
the outgoing end thereof with a platelike member possessing a material 
guiding surface substantially flush with the upper surface of the first 
conveyor. The length of the platelike member in the direction of 
conveyance is not particularly limited but may be suitably selected 
depending on the amount of the material to be delivered and the viscosity 
and other physical properties of the material. Generally, this length is 
desired to be in the range of 50 to 500 mm, preferably 100 to 300 mm. 
For this invention, the kind of the material to be handled is not critical. 
The invention manifests its effect particularly conspicuously for a wet 
material. The term "wet material" as used herein refers to a material 
which exhibits viscosity on absorption of water. Hydrated gels of 
hydrophilic polymers may be cited as typical examples of the wet material. 
Particularly when the hydrophilic polymer is what has been obtained by 
polymerizing a monomer component containing 50 to 100% by weight, 
preferably 75 to 100% by weight, of acrylic acid (or a salt thereof) 
neutralized to a ratio in the range of 0 to 100 mol %, preferably 50 to 90 
mol %, with the hydroxide of an alkali metal or ammonia, the method of 
this invention operates effectively in particular because the viscosity to 
be assumed by the polymer is strong. 
Although the method for the production of the hydrophilic polymer is not 
specifically limited, when the method is carried out batchwise, large 
amount of the hydrated gel of the hydrophilic polymer is discharged 
intermittently, so the method for metered supply in accordance with the 
present invention is preferably applied as an intermediated process for 
supplying the hydrated gel to the following step such as a drying step. 
As disclosed in Japanese Patent Laid-Open SHO 57(1982)-34,101, the method 
for aqueous polymerization under finely dividing the hydrated gel polymer 
by shearing force of the rotation of plurality of the stirring blade in a 
vessel provided with the blades is preferable, because the product by 
polymerization can be directly charged to the drying step by the method 
for metered supply of the present invention. 
The concentration of the monomer in the aqueous solution is preferably in 
the range of 10 to 80% by weight, preferably 20 to 60% by weight. So long 
as the concentration falls in the range mentioned above, the hydrated gel 
polymer formed in consequence of the progress of the polymerization is 
finely divided easily by the shearing force generated by the rotation of 
the stirring shaft. 
The monomers which are usable in this invention include water soluble 
monomers such as acrylic acid and methacrylic acid and alkali metal salts 
or ammonium salts thereof and .alpha., .beta.-ethylenically unsaturated 
monomers such as acrylamide, methacrylamide, acrylonitrile, and 
2-hydroxyethyl (meth)acrylates, maleic aicd, for example. One member or a 
combination of two or more members selected from the group of 
water-soluble monomers enumerated above may be used. In such case, if 
necessary, methyl (meth)acrylate, ethyl (meth)acrylate, and isopropyl 
(meth)acrylate, may be used together with the above mentioned water 
soluble monomers in the range that the hydrophilicity is not damaged. 
Where the hydrophilic polymer is an absorbent resin, a cross-linking 
monomer is preferably used. The cross-linking monomers which are usable 
herein include diacrylates or dimethacrylates of ethylene glycol, 
diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, 
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, trimethylol propane, 
and pentaerythritol, triacrylates or trimethacrylates of 
trimethylolpropane and pentaerythritol, tetraacrylate or tetramethacrylate 
of pentaerythritol, and N,N'-methylenebisacrylamide, 
N,N'-methylenebismethacrylamide, and triallyl isocyanurate, for example. 
One member or a combination of two or more members selected from the group 
of cross-linking monomers enumerated above may be used. The amount of the 
cross-linking monomer to be used is generally not more than 10 mol %, 
desirably in the range of 0.005 to 5 mol %, and most desirably in the 
range of 0.01 to 1 mol %, based on the amount of the monomer mentioned 
above. 
Among these monomers mentioned above, a monomer mixture which consists of 
at least one monomer (A) selected from the group consisting of acrylic 
acid, methacrylic acid, and alkali metal salts thereof or ammonium salts 
thereof, acrylamide, methacrylamide, and a cross-linking monomer (B) 
possessing at least two polymerizable double bonds in the molecular unit 
thereof and contains the cross-linking monomer (B) in a ratio of not more 
than 10 mol % proves to be particularly desirable for the present 
invention. As the cross-linking monomer (B), one member or a combination 
of two or more members selected from the group of cross-linking monomers 
enumerated above may be used. If the amount of the cross-linking monomer 
(B) to be used exceeds 10 mol % based on the amount of the monomer (A), 
the cross-linking polymer to be produced is deficient in absorbing 
capacity and ion-exchange capacity. The ratio of the cross-linking monomer 
(B) is preferably in the range of 0.005 to 5 mol %, more preferably in the 
range of 0.01 to 1 mol %. The concentration of the monomer mixture in the 
aqueous solution thereof is preferably in the range of 10 to 80% by 
weight, more preferably 20 to 60% by weight. 
The invention has been described so far by adducing the case in which 
mainly the monomer is neutralized, as occasion demands, in a prescribed 
ratio. Optionally, the produced hydrophilic polymer may be neutralized 
either wholly or partially to the same ratio as mentioned above. 
The hydrated gel polymer consequently obtained has a water content in the 
range of 10 to 90% by weight, preferably 30 to 80% by weight, and an 
average particle diameter in the range of 0.05 to 50 mm, preferably 0.5 to 
20 mm. 
Now, the present invention will be described below with reference to 
working examples illustrated in the accompanying drawings. 
Example 
FIG. 1 is a schematic cross section illustrating a typical apparatus for 
metered supply of a material as one embodiment of the present invention. 
This apparatus 10 was installed between a device 1 for producing a 
hydrated gel of absorbent resin by batch polymerization and a drying 
device 11 for drying the hydrated gel. It was provided with a first 
conveyor, i.e. a belt conveyor 13 attached to a base 12. 
The producing device mentioned above was installed above the incoming end, 
i.e. the righthand part of the belt conveyor 13, and was operated for the 
production of the hydrated gel. This production was carried out as 
follows. A twin-arm type kneader of stainless steel having an inner volume 
of 1,000 liters, with two sigma type blades 6 and a jacket 4 was fitted 
with a lid. In the device, 550 kg of the aqueous solution of an acrylate 
type monomer comprising 438 kg of an aqueous sodium acrylate solution, 
41.4 kg of acrylic acid, and 70.6 kg of deionized water (monomer 
concentration 37% by weight and neutralization ratio 75 mol %) via a 
material supply inlet 3 and 0.1 kg of N,N'-methylenebisacrylamide were 
placed and swept with nitrogen gas introduced via a nitrogen gas inlet 2 
to displace the gas entrapped in the reaction system. 
Then, the two sigma type vanes 6 were rotated at a rate of 30 rpm and the 
kneader was heated by passing hot water at 25.degree. C. through the 
jacket 4 and, at the same time, 0.14 kg of ammonium persulfate and 0.2 kg 
of sodium hydrogen sulfite were added as polymerization initiators to the 
mixture in the kneader. The monomer component began to polymerize five 
minutes after the addition of the polymerization initiators. The internal 
temperature of the reaction system reached 92.degree. C. within 20 minutes 
of the addition of the initiators, with the produced hydrated gel polymer 
finely divided into particles 1 to 5 mm in diameter. The polymerization 
was completed in 60 minutes. Then, the hydrated gel was removed from the 
kneader. 
The removed hydrated gel was thrown onto the belt conveyor 13 via a hopper 
14 which, as illustrated in FIG. 1, was installed above the incoming side 
of the belt conveyor 13. This belt conveyor 13 was passed round a driving 
roller 15 and a following roller 16 both attached to the base 12. In order 
for the belt conveyor 13 to be advanced in the direction of the arrow 
shown in FIG. 1 by a motor 17 disposed on a supporting base, a chain 18 
was passed, as illustrated in FIG. 1, around a sprocket fixed on the main 
shaft of the motor 17 and a sprocket fixed to the driving roller 15. 
To the hopper 14, a gate member 20 was integrally joined. This gate member 
20, as illustrated in FIG. 2, was bent at the central part thereof falling 
in the middle of the width of the belt conveyor 13 toward the downstream 
side relative to the opposite lateral edges of the conveyor 13 so as to 
assume the shape of the letter V written in a widely divergent pattern. 
When the hydrated gel was thrown in a heaped state, as illustrated in FIG. 
1, onto the incoming end of the conveyor 13 and the conveyor 13 was 
advanced, the heap of the hydrated gel was regulated to the thickness, d, 
equalling the gap between the lower surface of the gate member 20 and the 
upper surface of the conveyor 13 while the part of the heap positioned in 
the middle portion of the width of the conveyor was pressed against the 
opposite lateral edges. 
Optionally, in the place of the gate member 20, a roller may be 
incorporated in the hopper 14 and operated to regulate the thickness of 
the heap of the hydrated gel being advanced on the belt conveyor 13. 
The belt conveyor 13 was provided at the left end thereof with a platelike 
member, i.e. a receiving plate 21, disposed flush with the upper surface 
of the conveyor 13. This receiving plate 21 constituted itself the 
outgoing end of the belt conveyor 13. The receiving plate 21 had a length 
proportionate to the width of the belt conveyor 13. The receiving plate 21 
as used in the illustrated embodiment had, in the direction of advance of 
the conveyor 13, a size in the range of 150 to 200 mm. The receiving plate 
21 so disposed effectively prevented the hydrated gel from falling after 
the pattern of an avalanche. Above the left end part of this receiving 
plate 21, a rotary shaft 22 was supported rotatably by a supporting member 
(not shown) as held substantially perpendicularly to the direction of 
advance of the belt conveyor 13. This rotary shaft 22 was adapted to be 
driven by a motor 23 through the medium of a chain 24 which was passed 
round a sprocket fixed to the motor 23 and a sprocket fixed to the rotary 
shaft 22 as illustrated in FIG. 2. This rotary shaft 22 was so disposed 
that the axis thereof would vertically coincide substantially with the 
left edge of the aforementioned receiving plate 21. 
On the rotary shaft 22, a multiplicity of blade members 25 destined to 
constitute a scraping member were radially fixed (shown in FIG. 3). These 
blade members 25 possessed a width proportionate to the width of the 
conveyor 13 and a uniform length from the axis of the rotary shaft 22 to 
the leading end of the blade members. A scraper 26 consisted of the rotary 
shaft 22 and the blade members 25. In the illustrated embodiment, a total 
of 12 blade members 25 were circumferentially spaced at angular intervals 
of 30.degree. relative to the axis of the rotary shaft 22. 
Since the rotary shaft 22 was adapted to be rotated in the direction 
indicated by the arrow, the blade members 25 were moved in the direction 
of advancing the heap of the hydrated gel being transferred on the belt 
conveyor 13 in consequence of the rotation of the rotary shaft 22. The 
revolving speed of the leading ends of the blade members 25, namely the 
peripheral speed v was set at a level in the range of 5 to 500 times the 
conveying speed, V, of the belt conveyor 13. A gap, d, was allowed to 
intervene between the leading end of the blade member 25 rotated to the 
lowermost level and the upper surface of the belt conveyor 13. This gap d 
was set at a magnitude approximately in the range of 3/4 to 1/4, 
preferably 1/2 to 1/3, of the aforementioned gap D. 
The hydrated gel advanced by the belt conveyor 13 and regulated to the 
aforementioned thickness D by the gate member 20 was pressed down while in 
the process of passing the gate member 20 and consequently caused to 
acquire a relatively high bulk density throughout the entirety of the 
thickness. The thickness, D, was approximately in the range of 300 to 
1,000 mm, preferably 350 to 700 mm. When the thickness, D, of the hydrated 
gel was transferred infallibly without entailing the phenomenon of 
slippage on the conveyor 13. 
When the layer of hydrated gel A was brought to the position above the 
receiving plate 21 forming the outgoing end of the conveyor 13, part of 
the blade members 25 as scraping members plunged down into the hydrated 
gel layer A of the thickness D to a depth in the range of 3/4 to 3/4 of 
the thickness D and disintegrated and scraped the upper side part of the 
hydrated gel layer in the direction of conveyance at a peripheral speed 
greater than the conveying speed of the conveyor 13. As the result, the 
upper side part of the hydrated gel layer which had been compacted under 
pressure and had consequently gained in bulk density was discharged in a 
disintegrated state onto the drying device 11 by the blade members 25 and, 
at the same time, the lower side part of the hydrated gel layer was pushed 
forward by the upper side part of the hydrated gel being advanced by the 
conveyor and was discharged onto a second conveyor, i.e., a conveyor 27 
and charged to the drying device 11. In such case, conveying speed of the 
conveyor 27 is 3 to 50 times to the speed V of the conveyor 13. Since the 
lower side part of the hydrated gel layer had a small thickness and a 
proportionately small binding force, it was readily disintegrated and 
discharged. The part of the layer removed by the blade members 25 and the 
part discharged from the belt conveyor 13 were thoroughly disintegrated 
and delivered continuously to the drying device 11 for the next step of 
treatment. To the next step, therefore, the hydrated gel as a material was 
supplied infallibly in a prescribed rate with high accuracy. 
FIG. 4 (A) is a diagram illustrating a scraping device 26 in another 
embodiment of the invention. A cylindrical rotary member 30 was provided 
on the circumferential boundary thereof with a multiplicity of depressed 
surfaces 31 which were extended straight throughout the entire axial 
length of the rotary member 30. Owing to this configuration, a plurality 
of scraping members 32 of a small width extended in the direction of width 
of the belt conveyor 13 were formed. In this embodiment, the action of 
scraping the upper side part of the hydrated gel layer was obtained 
similarly to the preceding embodiment. 
FIG. 4 (B) is a diagram illustrating a scraping device 26 in yet another 
embodiment of the present invention. In this case, a rotary shaft 35 was 
provided on the circumferential boundary thereof with a spirally 
continuous ribbonlike blade 36. The upper side part of the hydrated gel 
layer was subjected to the moving force generated by the spiral blade 36 
in the direction of width of the belt conveyor 13 and, at the same time, 
to the disintegrating force produced by the blade 36 owing to the partial 
velocity of its rotation in the direction of conveyance coupled with the 
fact that the hydrated gel itself possessed viscosity and consequently 
exhibited an inclination to adhere to the blade 36. The disintegrated 
hydrated gel was discharged to the next step. In this case, the 
disintegrating force was manifested conspicuously. 
When the direction of the spiral curve of the spiral blade 36 illustrated 
in FIG. 4 (B) was reversed in the central part of the rotary shaft 35, the 
hydrated gel subjected to the disintegrating action was gathered in the 
central part in the direction of width of the belt conveyor 13 or moved 
away toward the opposite lateral parts of the belt conveyor 13. 
By making further use of the fact that the hydrated gel, because of its 
viscosity, had an inclination to adhere to the blade, such a modification 
of the scraping device 26 as illustrated in FIG. 4 (C) could be realized. 
On a rotary shaft 38, a multiplicity of rod members 39 were radially 
projected. These rod members 39 served as a scraping member. In this case, 
though the hydrated gel on the conveyor 13 was not scraped off all at once 
throughout the entire width of the belt conveyor 13, part of the hydrated 
gel was scraped off. The part of the hydrated gel which adjoined to the 
particular part which had been scraped off was entrained by the scraped 
part because of the viscosity and, consequently, subjected to the 
disintegrating action exerted upon the hydrated gel similarly to the 
embodiments described above. 
FIGS. 5 (A) and (B) are diagrams illustrating apparatuses for metering the 
supply of a material as other embodiments of the present invention. Unlike 
the apparatuses illustrated in FIG. 1 and FIG. 2, these apparatuses had no 
gate member 20 incorporated in the hopper 14 and were adapted instead to 
rely upon the scraping device 26 for the fulfilment of the function of the 
gate member 20. This scraping device 26, as illustrated in FIG. 5 (B), was 
provided with an outgoing side roller 40 positioned above the receiving 
plate 21 and an incoming side roller 41 positioned on a higher level on 
the incoming side of the conveyor 13. An endless belt 42 was passed round 
the rollers 40 and 41. This belt 42 was inclined in such a manner that the 
distance between the belt 42 and the belt conveyor 13 decreased in the 
direction of the outgoing end of the conveyor as illustrated. On the 
circumferential surface of this belt 42, a multiplicity of blade members 
43 extended in the direction of width were spaced at fixed intervals. Also 
in this case, since the moving speed, v, of the leading ends of the blade 
members 43 was greater than the moving speed, V, of the belt conveyor 13, 
the hydrated gel thrown onto the belt conveyor 13 was pressed against the 
lower surface of the belt 42, eventually regulated in thickness and, at 
the same time, disintegrated by being scraped off by the blade members 43. 
In an experimental operation of the apparatus for metered supply 
illustrated in FIG. 1 to FIG. 3, the hydrated gel introduced from the 
aforementioned twin-arm type kneader onto the incoming end of the belt 
conveyor 13 under the conditions mentioned above was transferred on the 
belt conveyor 13 to the drying device 11, with the conveying speed, V, set 
at 0.06 m/min, the peripheral speed, v, at 4 m/min, the gap, D, at 500 mm, 
and the gap, d, at 200 mm respectively. The hydrated gel was introduced 
into the drying device 11 and spread on the belt of the drying device 11 
in the form of a fluffy layer having a uniform thickness in the range of 
45 to 50 mm and having no compacted texture. Inside the drying device 11, 
the hydrated gel was continuously dried for 120 minutes with hot air 
supplied therein at a temperature of 150.degree. C. As the result, a dry 
polymer having a water content in the range of 5 to 7% by weight was 
obtained. When this dry polymer was treated with a pulverizer, an 
absorbent resin powder composed of particles measuring not more than 1 mm 
in diameter was obtained. 
It was not desirable to decrease the aforementioned size, d, close to zero 
because the small size caused the scraping member rather to compact the 
hydrated gel than to disintegrate it. The function of thoroughly 
disintegrating the hydrated gel and simultaneously discharging it to the 
next step was attained fully by causing the upper side part of the 
hydrated gel layer to be disintegrated and discharged by the scraping 
member. 
To facilitate the comprehension of the basic principle and the operation 
and effect of this invention, the configuration of the apparatus for 
metered supply which was tried during the course of development of this 
invention is schematically illustrated in FIG. 6. In this case, the 
hydrated gel thrown onto a belt conveyor 50 was passed through a gate 51 
and then introduced into a drying device 52 by the motion of the belt 
conveyor 50. From the outgoing end of the belt conveyor 50, however, the 
hydrated gel fell down in separate blocks and formed heaps on the conveyor 
of the drying device 52. When these heaps in the drying device 52 were 
dried for 10 hours with a forced current of hot air at 150.degree. C., the 
hot air failed to reach the interiors of the heaps. Consequently, the 
heaps emanating from the drying device contained undried gel in their 
interiors. When the heaps were manually crushed and supplied to a 
pulverizer, the undried hydrated gel clogged the drying device and 
eventually stopped device. 
Industrial Applicability 
As described above, in accordance with the present invention, the material 
in the process of transfer on the conveyor is regulated to a thickness 
such that the phenomenon of slippage will not occur between the conveyor 
and the material and, during the course of the regulation of thickness, 
the material is caused to gain in bulk density owing to the action of 
compaction under the pressure. The upper side part of the compacted layer 
of the material, on reaching the outgoing end of the conveyor, is cut and 
scraped and discharged by the scraping member to the next step. In the 
meantime, the lower side part of the compacted layer of the material not 
discharged by the scraping member is thin enough to be sufficiently loosed 
exclusively by the force of motion of the conveyor owing to the 
aforementioned removal of the upper side part by the scraping member. The 
material discharged from the conveyor, therefore, is as a whole in a 
sufficiently loose state and thus is continuously delivered to the next 
step. The metered supply of the material, accordingly, is accomplished 
infallibly with high accuracy. 
In accordance with the method of this invention which produces a 
hydrophilic polymer by the use of the aforementioned apparatus for metered 
supply, since the hydrated gel polymer formed by the batch polymerization 
is supplied to the drying device without being compacted under pressure, 
the produced hydrophilic polymer contains absolutely no undried hydrated 
gel polymer and the hydrophilic polymer can be produced in a notably 
improved productivity.