JP2001131218A - Method for conveying hydrous gel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for conveying a hydrous gel whereby the gel is prevented from sticking to the carrying surface of a conveying means and can be smoothly conveyed. SOLUTION: When a hydrous gel 19 obtained by polymerizing a water-soluble ethylenic unsaturated monomer is conveyed with a conveying means comprising a conveyer belt 16, rotating rolls 40, etc., water 45 is supplied to (1) between the carrying surfaces of the conveying means carrying the gel 19, i.e., the roll surfaces of the rolls 40, and the gel 19; and water 45 and 43 is supplied to (2) the vicinity of areas supported by the inside face of the side weir formed on the roll surfaces or the conveyor belt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for transporting a hydrogel, such as a hydrogel obtained by polymerizing a water-soluble ethylenically unsaturated monomer.

[0002]

2. Description of the Related Art Water-absorbing polymers have been applied to a wide variety of applications such as absorbents for sanitary articles such as sanitary articles and disposable diapers; drip absorbents; These water-absorbing polymers are first produced in the form of a hydrogel by polymerizing a water-soluble ethylenically unsaturated monomer as a raw material in a batch system or a continuous system.

[0003] The hydrogel produced as described above is
Subsequently, it is carried out of the polymerization section, and is carried into, for example, a gel crusher and crushed to a predetermined size. Then, the crushed hydrogel is carried into a gel refiner and granulated,
For example, it is a granular gel (a form of a water-absorbing polymer) having a predetermined average particle size. The granular gel is further dried, if necessary, and then finely pulverized by a mill-type pulverizer to obtain water-absorbing fine particles (one form of a water-absorbing polymer).

[0004] The carry-out and carry-in of the hydrogel from the polymerization section to the gel crusher are performed, for example, by using an endless belt disposed between the polymerization section and the gel crusher (including the inside of the polymerization section and the gel crusher). , Etc., is carried out by being supported by a support surface of a conveying means (conveyor).

[0005]

By the way, since hydrogel is generally sticky, for example, when the hydrogel is carried out from the polymerization section to the gel crusher as described above, it is necessary to use a conveyance means. Easy to adhere to the support surface. As a result, in the transporting means, it is easy to cause a cause that hinders smooth transporting of the hydrogel, such as catching, clogging, loosening, and entanglement. Further, as a result, there is a possibility that the hydrogel is elongated and cracked or cut. When the hydrogel is cracked or the hydrogel is cut, 1) the hydrogel is easily entangled between a guide roll, a rotating roll, or the like from the crack or the cut portion, and 2) the hydrogel. The cracks or cut portions of the gel are more likely to be caught near the entrance of the gel crusher, and the like, and the smooth conveyance of the hydrogel becomes more difficult.

More specifically, 1) When the endless belt is conveyed to a guide roll, a rotating roll, a roller conveyor, or the like, the water-containing gel adhered to the support surface of the endless belt is hardly peeled off, and the conveyance is smooth. There is a risk that this will not be done. 2) When the hydrogel is conveyed on guide rolls, rotating rolls, and roller conveyors,
The hydrogel may adhere to the support surface of the guide roll or the rotating roll, and a portion of the hydrogel adhered to the support surface may be caught between the rolls, so that the transport may not be performed smoothly. In particular, when a water-soluble ethylenically unsaturated monomer is subjected to static polymerization in a continuous system, a portion where polymerization is partially slow (incomplete) may occur for some reason.
In this case, there is a possibility that the tackiness is particularly high, and the portion tends to be stuck to the support surface of the transporting means, which tends to inhibit smooth transport of the hydrogel.

If the hydrogel is caught or clogged as described above, labor must be required to remove the gel. In particular, when the water-soluble ethylenically unsaturated monomer is polymerized in a continuous manner, the operation of the production apparatus must be stopped in some cases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to prevent the hydrogel from sticking to the support surface of the conveying means, thereby enabling the hydrogel to be smoothly conveyed. It is an object of the present invention to provide a method for transporting a hydrogel.

[0009]

In order to solve the above-mentioned problems, the method for transporting a hydrogel according to the present invention is a method for transporting the hydrogel by supporting the hydrogel with a support surface provided on the transport means. A step of supplying water between the support surface and the hydrogel, and / or in the vicinity of a region of the hydrogel that is supported by the support surface,
Peeling off the hydrogel from the support surface and carrying it out of the transporting means.

In order to solve the above-mentioned problems, the method for transporting a hydrogel according to the present invention further comprises supporting the hydrogel with a support surface provided on a conveying means and moving the hydrogel relative to the support surface. Wherein the method comprises a step of supplying water between the support surface and the hydrogel and / or in the vicinity of the region of the hydrogel supported by the support surface. .

[0011] In order to solve the above-mentioned problems, the method for transporting a hydrogel according to the present invention further comprises the step of subjecting the hydrogel obtained by statically polymerizing a water-soluble ethylenically unsaturated monomer on an endless belt to: In the method for transporting hydrogel supported and transported by the support surface of the endless belt, the support surface may be disposed between a side end of the hydrogel in the transport direction rear side of the hydrogel and / or the hydrogel. It is characterized by comprising a step of supplying water to the vicinity of a side end portion in the rear in the transport direction, and a step of peeling the hydrogel from the endless belt and carrying it out of the endless belt.

In order to solve the above-mentioned problems, the method for transporting a hydrogel according to the present invention further comprises the step of setting the temperature of the support surface to be equal to or lower than the dew point of the atmosphere so that the water is supplied as dew. Features.

[0013] In order to solve the above-mentioned problems, the method for transporting a hydrogel according to the present invention further comprises the step of transporting the hydrogel by a transport means, wherein water is supplied to the hydrogel and / or the transport means. The method is characterized by including a supplying step.

In order to solve the above-mentioned problems, the method for transporting a hydrogel according to the present invention further comprises the step of transporting the hydrogel by supporting and transporting the hydrogel with a roll provided in a transport means. And / or supplying water to the roll.

In order to solve the above-mentioned problems, the method for transporting a hydrogel according to the present invention further comprises a step of supporting and transporting the hydrogel with a plurality of rolls provided in the transport means. And

In order to solve the above problems, the method for transporting a hydrogel according to the present invention is such that the hydrogel is obtained by statically polymerizing a water-soluble ethylenically unsaturated monomer. It is characterized by:

The method for transporting a hydrogel according to the present invention is characterized in that, in order to solve the above-mentioned problems, the method further comprises a step of heating the hydrogel conveyed by the conveying means.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Note that the present invention is not limited by this.

[Method of transporting hydrogel] The method of transporting the hydrogel according to the present invention is a method of transporting the hydrogel by supporting and transporting the hydrogel with a support surface provided on the transport means. A step of supplying water between the support surface supporting the hydrogel and the hydrogel and / or 2) near the region of the hydrogel supported by the support surface. .

In the present invention, the “hydrogel” refers to a gel-like substance containing water and having tackiness. Specific examples of such a gel-like substance include a hydrogel obtained by polymerizing a water-soluble ethylenically unsaturated monomer.

The above “ethylenically unsaturated monomer” is
There is no particular limitation as long as it is a water-soluble ethylenically unsaturated monomer that can be used as a raw material for the water-absorbing polymer described below. Specifically, for example, acrylic acid and its salts; methacrylic acid and its salts; acrylamide; methacrylamide; acrylonitrile; 2-hydroxyethyl (meth) acrylate; methyl acrylate; ethyl acrylate; Ethyl methacrylate; maleic acid; and the like. Among the ethylenically unsaturated monomers exemplified above, acrylic acid and salts thereof (more specifically, Li, Na, K
Alkali metal salts, ammonium salts, etc.) are suitably used as the main raw material. These ethylenically unsaturated monomers may be used alone in the polymerization reaction, or two or more of them may be used as a mixture. Hereinafter, the ethylenically unsaturated monomer is simply referred to as a monomer in some cases.

More preferably, the monomer is subjected to a polymerization reaction as a solution containing the monomer (hereinafter, referred to as a monomer solution). As the monomer solution,
An aqueous monomer solution is more preferred. The concentration of the monomer aqueous solution is not particularly limited, but is preferably 20% by weight (mass percentage) to 50% by weight, more preferably 30% to 45% by weight. When the concentration is 20% by weight or more, the strength of the obtained water-absorbing polymer can be reliably set to a practical value. Also, 5
When the content is 0% by weight or less, heat of reaction generated by the polymerization reaction can be easily removed, and the polymerization reaction can be reliably controlled. Further, it is more preferable that an inert gas is supplied to the monomer solution before the monomer solution is subjected to a polymerization reaction to remove dissolved oxygen contained in the monomer solution. The degree of removal of dissolved oxygen from the monomer solution is not particularly limited, but the amount of dissolved oxygen in the monomer solution is
More preferably, it is 2 mg / l or less, and 1 mg / l.
More preferably,

As a result of the polymerization reaction, a hydrogel is produced as one form of the water-absorbing polymer. In the present invention, the water-absorbing polymer is a hydrogel produced by polymerizing the above-mentioned "ethylenically unsaturated monomer" unless otherwise specified, and the hydrogel is pulverized and / or dried. Is a generic name for granular gels, water-absorbing fine particles, etc. obtained by applying

In the present invention, the transport means is not particularly limited as long as it is a transport means which comes into contact with the above-described hydrogel and has a support surface for supporting it. The transporting means includes: a) transporting the hydrogel while maintaining the relative positional relationship between the support surface and the hydrogel constant; for example, transport of a transport belt such as an endless belt (ie, a belt conveyor); Means (referred to as relative stop type transport means)
And b) a guide roll that moves the hydrogel relative to the support surface of the conveying means, for example, is rotatably provided and does not require a driving force; a driven roll; a plurality of rotary rolls or a guide roll And a transporting means (referred to as a relative moving type transporting means). In addition, a rotating body supported by a shaft, such as a guide roll and a rotating roll, is hereinafter simply referred to as a roll. The support surface is more specifically provided, for example, on a belt surface or a roll surface that supports the hydrogel from below, and on both sides in the width direction of the transport belt that supports the hydrogel from the side. An inner surface such as a weir (side weir) or a brim provided at both ends of the roll may be mentioned, but is not particularly limited as long as it is a planar structure that comes into contact with and supports the hydrogel as described above. .

The “water” may be 1) between a support surface for supporting the hydrogel and the hydrogel, and / or
2) The hydrated gel is supplied to at least a part near the region supported by the support surface, more preferably to the entire region. As a result, a) the hydrogel swells, and in the case of 1), further, b) a water layer is formed between the support surface and the hydrogel, and the hydrogel adheres to the support surface. Be prevented. In addition, it is possible to release the hydrogel once adhered to the support surface from the support surface. The timing of performing the above-described step of supplying water is not particularly limited.Before the hydrogel is brought into contact with the support surface, any timing during the time when the hydrogel is in contact with and supported by the support surface is used. Good. However, when water is supplied between the support surface and the hydrogel, it may be easier to supply water before the hydrogel contacts the support surface.

The method for supplying water to the support surface or the hydrogel is not particularly limited. Specifically, for example, 1) a method of spraying water using a spray or the like, 2) A method of supplying water as droplets, 3) a method of supplying water as dew on the support surface by setting the temperature of the support surface to be equal to or lower than the dew point of the atmosphere. More specifically, the method of the above 3) is, for example, a) by directly cooling the support surface, or b) flowing cold air / cold water behind (inside) the support surface. Indirect cooling of the support surface by the method described above means that the temperature of the support surface is set to be equal to or lower than the above-mentioned dew point to cause dew condensation of water (usually water in steam). These methods are
One type may be used alone, or two or more types may be used in combination. Further, these waters may be supplied intermittently or continuously.

It should be noted that a method of supplying water as a stream is not particularly excluded. However, if a large amount of water is used in the step, a post-treatment (more specifically, crushing,
(Granulation, drying, etc.). Therefore, the supply amount of water needs to be determined in consideration of the balance with post-treatment in some cases.

In the above-mentioned water, if necessary, additives such as a surfactant, a water-soluble salt, and the like, a polymerization initiator, a deodorant,
Functional materials such as antibacterial agents, thickeners, chelating agents, etc. can be included. The water may further contain, for example, a hydrophilic organic solvent such as various alcohols, a water-soluble compound, or an ethylenically unsaturated monomer, if necessary. Further, the temperature of the “water” is not particularly limited, but is preferably in the range of 0 ° C. to 80 ° C., and more preferably in the range of 5 ° C. to 50 ° C.

As described above, according to the method for transporting hydrogel according to the present invention, it is possible to prevent the hydrogel from sticking to the support surface of the transport means. In addition, it is possible to release the hydrogel once adhered to the support surface from the support surface. Thereby, in the above-mentioned conveying means, it is possible for the hydrogel to be caught, clogged, slack, entangled, etc.
It is possible to prevent and suppress the occurrence of a cause that hinders smooth conveyance. As a result, it is possible to eliminate the possibility that the hydrogel is stretched during transportation and cracks or cut.

More specifically, when the transport means is a relatively movable transport means such as a guide roll, a rotary roll, or a roller conveyor, the hydrogel may adhere to the support surface of the transport means. Is prevented. Therefore, for example, the hydrogel can be smoothly moved (that is, conveyed) relative to the support surface without causing the hydrogel to be caught between the rolls. Further, in the case where the transporting means is a relative stop type transporting means, it is possible to prevent the hydrogel from sticking to the support surface of the transporting means. As a result, the hydrogel can be easily peeled off from the support surface, so that the hydrogel can be smoothly carried out of the transport means, for example, to a guide roll, a rotating roll, a roller conveyor, or the like.

In particular, when the above-mentioned monomer is subjected to static polymerization, a portion where polymerization is partially slow (incomplete) may occur. In such a case, in the manufactured hydrogel, there is a possibility that the tackiness of the portion is particularly high, and the gel may adhere to the support surface of the transporting unit and hinder smooth transport. However, by applying the method for transporting a hydrogel according to the present invention, it is possible to prevent or suppress the occurrence of such a factor that hinders smooth transport.

When the polymerization and post-treatment of the above-mentioned monomer are carried out in a continuous manner, if the hydrated gel sticks to the support surface, there is a possibility that the operation of the whole manufacturing apparatus must be stopped. Therefore, the benefit of applying the method for transporting a hydrogel according to the present invention is particularly large. Hereinafter, an apparatus for producing a water-absorbing polymer to which the method for transporting a hydrogel according to the present invention is applied will be described with reference to the drawings.

[Production Apparatus for Water Absorbent Polymer] The above production apparatus is, for example, as shown in FIG. 1, a monomer tank 11 for storing a monomer as a raw material of the water absorbent polymer as a solution thereof; Ejector 12 for supplying gas; initiator tank 13 for storing a polymerization initiator and an oxidizing initiator forming a redox-based initiator, respectively; reducing agent tank 14 storing a reducing agent forming a redox-based initiator; A mixing column 15 for mixing a monomer and a polymerization initiator (including a redox initiator composed of an oxidizing initiator and a reducing agent);
From the nozzle port 15a provided in the mixing tower 15, the polymerization machine 1
The conveyor belt (conveying means) 16 continuously conveys the monomer supplied in the conveying direction in the conveying direction. Mixing tower 1
A spray 30 a as a means for supplying water 30 b connected to the water storage tank 30 into the mixing tower 15 is provided in the upper part of the inside 5. In addition, in the manufacturing apparatus shown in FIG.

In the monomer tank 11, the above monomer is
For example, as an aqueous solution (hereinafter referred to as an aqueous monomer solution)
The monomer aqueous solution is stored, and after the dissolved oxygen is removed by an inert gas (nitrogen gas) supplied from the ejector 12, the monomer aqueous solution is supplied to the mixing tower 15 via the monomer supply path 17 and the charging port 15c. Is done. Simultaneously with or before the introduction of the monomer aqueous solution, the spray 30a starts continuous spraying of the water 30b onto the inner surface of the mixing tower 15.

The mixing tower 15 includes: 1) a first mixing section (also serving as a cyclone chamber) in which an aqueous monomer solution flows along a spiral line; and 2) a second mixing section following the first mixing section. And a mixing section. The first mixing section is configured, for example, by combining an inner surface formed in a columnar shape and an inner surface formed in a truncated cone shape. The second mixing section is, for example, a thin tube having a constant cross-sectional area, and the lower portion thereof is slightly bent with respect to the vertical line (more specifically, the same direction as the transport direction of the transport belt 16). To bend).

In the first mixing section, the aqueous monomer solution introduced from the monomer supply path 17 through the inlet 15c flows along the above-mentioned line, and a swirling flow of the aqueous monomer solution is formed. Thereby, the bubbles of the inert gas can be removed (defoamed) from the aqueous monomer solution. Also,
In parallel with the removal of the inert gas, an oxidizing initiator such as sodium persulfate (NaPs); a polymerization initiator such as an azo-based initiator, if necessary; 13a are supplied and mixed.

The aqueous monomer solution from which the inert gas has been removed and the oxidizing initiator has been mixed is subsequently introduced into the second mixing section. In the second mixing section, for example, L-ascorbic acid (L-
A) The reducing agent such as A) is supplied via the reducing agent supply passage 14a.
Line mixed. Thereby, the monomer, the oxidizing initiator, and the reducing agent are mixed, and the polymerization reaction is started.

Subsequently, the monomer aqueous solution introduced into the mixing tower 15 passes through a nozzle belt 15a formed in the second mixing section, which also serves as a charging pipe, through a transport belt 16 provided in a polymerization machine 18. On the upper surface (belt surface, support surface). At this time, the monomer aqueous solution is supplied from the charging pipe to the polymerization machine 18.
Simultaneously with or before the charging, 1) water 30b sprayed by the spray 30a is supplied to the inner surface of the charging tube, and 2) supply means (not shown) to the outer surface of the charging tube. As a result, water is intermittently supplied as the flow.

The above-mentioned charging tube is bent in the same direction as the conveying direction of the aqueous monomer solution by the conveying belt 16. This bent structure is a structure for 1) to smoothly supply the monomer aqueous solution to the upper surface of the transport belt 16 and 2) to make the supply amount of the monomer aqueous solution to the upper surface of the transport belt 16 constant. It is not particularly limited to this structure. The supply amount of the monomer aqueous solution to the upper surface of the conveyor belt 16 (feed amount: equivalent to the liquid thickness when the width of the nozzle port 15a is fixed) is not particularly limited, but the liquid thickness is 1 mm to 50 mm. , More preferably within a range of 10 mm to 40 mm, and even more preferably within a range of 20 mm to 30 mm. When the liquid thickness is 1 mm or more, the production of the water-absorbing polymer can be performed at an industrial level.
Further, if the liquid thickness is 50 mm or less, it is easy to remove the reaction heat generated by the polymerization reaction, bumping during the polymerization reaction, increase in the soluble component contained in the resulting water-absorbing polymer,
A decrease in the strength of the water-absorbing polymer can be prevented.

More specifically, the transport belt 16 is supported and supported by drive shafts 20 rotating at a constant speed in the same direction.
A driven endless type belt conveyor (endless belt), and a hood 41 provided thereabove.
And is replaced with nitrogen. In addition, the upper surface of the transport belt 16 is cooled in a certain area (cooling zone 18a) located on the front side in the transport direction, and is heated in a certain area (heating zone 18b) located on the latter side in the transport direction. I have. The terms "heating" and "cooling" used herein are based on the temperature of the reaction system.

As shown in FIG.
Further, side dams 16a are provided on both sides in the width direction. The side weirs 16a, 16a
6 prevents the monomer solution supplied to the upper surface of the liquid crystal 6 from overflowing outside the upper surface. The height of the side weirs 16a may be appropriately set according to the liquid thickness of the supplied monomer aqueous solution, and is not particularly limited, but is generally in the range of 5 mm to 100 mm. Also, the side dam 16a
The material of 16a is not particularly limited as long as it does not deteriorate or dissolve when it comes into contact with the aqueous monomer solution. Specifically, for example, nitrile rubber, silicone rubber, chloroprene rubber, fluororubber, fluorine And the like. The side dams 16a, 16a
Is more preferably provided, but may not be provided.

The transport belt 16 is passed through the nozzle port 15a.
The monomer supplied (charged) to the upper surface of the polymer is continuously and statically polymerized on the upper surface. The polymerization reaction on the upper surface of the conveyor belt 16 is performed in the cooling zone 18a under cooling conditions for a certain period of time, and subsequently, is performed in the heating zone 18b under heating conditions for a certain period of time. As a result, the monomer aqueous solution subjected to the polymerization reaction is conveyed in the polymerization machine 18 by the conveyance belt 16, and the polymerization reaction is first performed while suppressing an excessive rise in the reaction temperature. Subsequently, a polymerization reaction and aging are performed while suppressing an excessive decrease in the reaction temperature, and a hydrogel (an embodiment of a water-absorbing polymer) 19 is produced.

As shown in FIGS. 1 and 2, water 43 is dropped and supplied from the water dropping devices (water supply means) 42 to the hydrogel 19 in the vicinity of the outlet of the polymerization machine 18. The water 43 is supplied by the side dam 16a of the hydrogel 19.
The process is performed in the vicinity of the area contacted and supported by the inner side surface (supporting surface) 16a 'of the 16a. Thereby, both ends in the width direction of the hydrogel (polymer gel) 19 slightly swell, and the hydrogel 19 is prevented from sticking to the side dams 16a. Also, once the side dams 16a, 16a
It is possible to release the hydrogel that has adhered to the side weirs from the side dams 16a. Therefore, it is possible to easily peel off the hydrogel 19 from the support surface of the transport belt 16 without generating scratches or cuts (cracks) at both ends of the hydrogel 19.

In the polymerization machine 18, 1) between the upper surface of the conveyor belt 16 and the hydrogel 19 or the side dam 16
a ・ 16a and the hydrogel 19
In this case, water may be supplied to the upper surface of the conveyor belt 16 or the inner side surfaces 16a ′ and 16a ′ of the hydrogel 19 in the conveying direction rear side, and the hydrogel 19 It is more preferable to supply water during. When water is supplied to the hydrogel 19, it is more preferable to supply water to a side end of the hydrogel 19 on the rear side in the transport direction.
By supplying water as described above, the water-containing gel 19 can be more easily separated from the support surface of the transport belt 16.

The hydrogel 19 peeled off from the support surface of the conveyor belt 16 is provided on a roller conveyor constituted by a plurality of rotating rolls (conveying means) 40 provided between the polymerization machine 18 and the gel crusher 21. (Conveying means). Below the rotating rolls 40, a water spraying device (water supply means) 44 for spraying water 45 upward is provided, whereby the roll surfaces (supporting surfaces) of the rotating rolls 40 ... Hydrogel 19 supported by the surface
Water is continuously supplied to the lower surface of the. As a result, 1) a water layer is formed between the roll surface and the lower surface of the hydrogel 19, and 2) the lower surface of the hydrogel 19 absorbs water and swells, so that the hydrogel 19 adheres to the roll surface. The fear can be reduced. Further, since the water-containing gel 19 has no scratches or cuts as described above, there is no risk of being caught or caught in a roll or the like. There is no possibility that the gel 19 is caught near the entrance of the gel crusher 21.

The hydrogel 19 carried into the gel crusher 21
Is crushed to a size of, for example, about 10 cm square. Subsequently, the crushed hydrogel 19 is granulated by a gel granulator 22 and has, for example, an average particle size of 0.5 mm to 3.0 mm.
mm granular gel (one form of a water-absorbing polymer). If necessary, the granular gel is further dried by a drier (not shown) and then finely pulverized by a mill-type pulverizer. For example, water-absorbing fine particles having an average particle diameter of 250 μm to 500 μm (one form of a water-absorbing polymer) It is said.

In the above polymerization reaction, a crosslinking agent may be used, if necessary. The crosslinking agent is not particularly limited as long as it has two or more functional groups in the molecule and contributes to the formation of a crosslinked structure. By performing a polymerization reaction in the presence of a crosslinking agent, a water-absorbing polymer having excellent durability can be obtained. In some cases, a crosslinking agent can be added to the hydrogel 19 obtained by the polymerization reaction to form a crosslinked structure. In this case, the hydrogel 19
Crosslinking agents having two or more epoxy groups, amino groups, hydroxyl groups, and the like, which are reactive with a functional group such as a carboxyl group in the molecule are preferably used.

The method for transporting a hydrogel according to the present invention is also a method for transporting a hydrogel by a transporting means, the method comprising a step of supplying water to the hydrogel and / or the transporting means. There may be.

According to the above-mentioned method, it is possible to realize smooth conveyance of the hydrogel without causing any trouble such as the hydrogel being caught by the conveying means and the hydrogel being cut. It works.

In the method for transporting a hydrogel according to the present invention, the method for transporting a hydrogel, wherein the hydrogel is supported and transported by a roll provided in a transport means, further comprises the step of adding water to the hydrogel and / or the roll. The method may include a supplying step.

According to the above method, it is possible to realize smooth conveyance of the hydrogel without causing any troubles such as the hydrogel being caught on the roll and the hydrogel being cut. It works.

The method for transporting a hydrogel according to the present invention may further include a step of supporting and transporting the hydrogel with a plurality of rolls provided in the transport means.

According to the above method, the hydrogel can be transported by a simple means of a plurality of rolls that do not require a driving force from a power source. The roll may require a driving force.

The method for transporting a hydrogel according to the present invention may further include a step of heating the hydrogel transported by the transport means.

According to the above method, the hydrated gel can be aged during the transportation, so that it is possible to reduce the residual monomers and soluble components contained in the hydrated gel.

The method for transporting a hydrogel according to the present invention further comprises the step of transporting the hydrogel obtained by polymerizing a water-soluble ethylenically unsaturated monomer while supporting the gel with a support surface provided in a transport means. The method of transporting the gel may include a step of applying an aqueous liquid between the support surface for supporting the hydrogel and the hydrogel.

In the method for transporting a hydrogel according to the present invention, the method for transporting a hydrogel, wherein the hydrogel is supported and transported by a support surface provided in a transporting means, further comprises: The method may include a step of supplying water between the hydrated gel and a step of peeling the hydrated gel from the support surface and carrying out the hydrated gel outside the transporting means.

In the method for transporting a hydrogel according to the present invention, the method for transporting a hydrogel, wherein the hydrogel is supported and transported by a support surface provided on a transport means, is further provided. The method may include a step of supplying water to the vicinity of the region to be formed, and a step of separating the hydrogel from the support surface and carrying it out of the transporting means.

The method for transporting a hydrogel according to the present invention further comprises the step of transporting the hydrogel by supporting the hydrogel on a support surface provided on the transport means and moving the gel relative to the support surface. It may be a method including a step of supplying between the supporting surface to be supported and the hydrogel.

The method for transporting a hydrogel according to the present invention further comprises the step of transporting the hydrogel by supporting the hydrogel on a support surface provided on the transport means and moving the gel relative to the support surface. And a step of supplying to the vicinity of the region supported by the support surface.

In the method for transporting a hydrogel according to the present invention, the method for transporting a hydrogel, wherein the hydrogel is transported while supported by a support surface provided on an endless belt as a transport means, further comprises the step of supporting the hydrogel. A step of supplying water between the supporting surface and the rear end of the hydrogel in the transport direction of the hydrogel, and a step of peeling the hydrogel from the endless belt and carrying it out of the endless belt. It may be a method comprising.

In the method for transporting a hydrogel according to the present invention, the hydrogel obtained by statically polymerizing a water-soluble ethylenically unsaturated monomer on an endless belt is supported by a support surface of the endless belt. In the method of transporting the hydrogel to be conveyed, the supporting surface for supporting the hydrogel, a side end portion in the conveyance direction rear of the hydrogel, a step of supplying water between the hydrogel, the hydrogel, Peeling from the above-mentioned area and carrying it out of the endless belt.

In the method for transporting a hydrogel according to the present invention, the hydrogel obtained by statically polymerizing a water-soluble ethylenically unsaturated monomer on an endless belt is supported by the support surface of the endless belt. In the method for transporting hydrogel, the step of supplying water to the vicinity of the side end of the hydrogel in the rear direction in the transport direction, and separating the hydrogel from the endless belt and carrying it out of the endless belt And a step of performing the method.

[0064]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 A water-absorbing polymer was produced using the production apparatus shown in FIGS. In the present embodiment, the transport belt (transport means) 16 is a side weir 16a / 1.
6a is 60 cm long and the length (ie, the drive shaft 20
It is an endless belt made of stainless steel of 24 m (center distance of 20). In addition, the side weirs 16a, 16a
It is about 5 cm high and made of rubber. The transport speed of the transport belt 16 is 1 m / min, the length of the cooling zone 18a is 15 m, and the length of the heating zone 18b is 9 m. The cooling zone is cooled to 15 ° C. by a cooler, and the heating zone is heated to 70 ° C. by a heater.

As a raw material of the water-absorbing polymer, 65% neutralized sodium acrylate (ethylenically unsaturated monomer) was used. First, a 35% by weight aqueous solution of the sodium acrylate was prepared, and a solution obtained by adding polyethylene glycol diacrylate as a cross-linking agent to the aqueous solution in an amount of 0.04 mol per 1 mol of sodium acrylate as an aqueous monomer solution. It was supplied to the monomer tank 11. continue,
Nitrogen gas (inert gas) was supplied at 1 L / min from the nozzle by the ejector 12, and the nitrogen gas was continuously blown into the flow (0.95 L / min) of the monomer aqueous solution supplied from the monomer tank 11. . Thus, dissolved oxygen contained in the monomer aqueous solution was continuously removed. As a result, the amount of dissolved oxygen in the monomer aqueous solution is
0.3 mg / L.

The monomer aqueous solution was subsequently charged (supplied) to the mixing tower 15. The mixing tower 15 has a Teflon coating inside, and 1) a first mixing section (also serving as a cyclone chamber) in which a monomer solution flows along a spirally shown line; and 2) a first mixing section. And a second mixing section following the section. The mixing tower 15
In the period from just before the supply of the aqueous monomer solution to the mixing tower 15 to the completion of the supply of the aqueous monomer solution, water 30b is sprayed at a rate of 10 ml / min from the spray 30a.
And sprayed continuously.

In the first mixing section, 0.5 mol% of 0.02 g was added to 1 mol of the sodium acrylate.
Aqueous sodium persulfate solution, 0.001 g of 0.14% by weight aqueous hydrogen peroxide (both oxidizing initiators)
0.5 wt% of 02G 2, 2 ^'- azobis (2-amidinopropane) dihydrochloride aqueous solution (thermal decomposition type initiator) was dropwise supplied different initiators tank 13 ... at the same time from each. Then, defoaming of nitrogen gas from the monomer aqueous solution by forming a swirling flow and mixing of the oxidizing initiator and the thermal decomposition initiator into the monomer aqueous solution were simultaneously performed.

The aqueous monomer solution exiting the first mixing section (also serving as a cyclone chamber) was introduced into the second mixing section (also serving as a charging pipe). In the second mixing section, 0.002 g of 0.2 mol / mol of the sodium acrylate was added.
A weight% L-ascorbic acid (reducing agent) aqueous solution was supplied from the reducing agent tank 14 and line-mixed with the monomer aqueous solution.

The aqueous monomer solution from which the nitrogen gas has been removed (defoamed) passes through a nozzle port 15a formed in the above-mentioned inlet pipe so that the transport belt 16 has a liquid thickness of 25 mm.
Was continuously charged on the upper surface (supporting surface) of. At this time, the charged height of the aqueous monomer solution was about 1 cm. The inner and outer surfaces of the charging pipe are coated with Teflon, and an aqueous monomer solution is charged into the polymerization machine 18 from the charging pipe to the outer surface of the charging pipe located in the polymerization machine 18. Prior to this, water was being supplied from above as an intermittent flow.

On the conveyor belt 16, the polymerization of sodium acrylate started about 30 seconds after the introduction of the aqueous monomer solution, and reached a polymerization peak 9 minutes later. The peak temperature at this time was 85 ° C. As a result of continuing the polymerization reaction for another 15 minutes after the polymerization peak, a hydrogel (one form of a water-absorbing polymer) 19 was produced.

The water-containing gel 19 was supplied with water at a flow rate of 5 ml / min from water dripping devices (supply means) 42. The hydrogel 19 peeled off from the support surface of the conveyor belt 16 was subsequently transferred to a roller conveyor (conveyor) composed of a plurality of rotating rolls (conveyor) 40. The roll surface (support surface) of the rotating rolls 40 and the hydrogel 1 supported by the roll surface
9 was sprayed with water 45 at a rate of 10 ml per minute from a water spraying device (water supply means) 44.

The hydrogel 19 carried into the gel crusher 21
Was crushed to a size of about 10 cm square. The crushed hydrogel 19 was then charged into a screw-type extruder (corresponding to a gel granulator 22) provided with spiral projections inside the body. Then, the hydrogel 19 was extruded from a perforated plate having a hole diameter of 9.5 mm provided in the screw-type extruder to granulate the hydrogel 19.

The granulated hydrogel 19, that is, the granulated gel was subjected to hot air drying at 170 ° C. for 43 minutes, and then subjected to a roll mill (mill type pulverizer) (not shown) to obtain a particle size of 850 μm.
m or less (not shown). continue,
The water-absorbing fine particles were classified with a sieve having a sieve of 150 μm, and particles having a particle size of 150 μm or less were removed. The average particle size of the water-absorbing fine particles obtained by the classification is about 300 μm
Met.

A surface crosslinking agent comprising 0.5 parts by weight of 1,4-butanediol, 0.5 parts by weight of propylene glycol, 1 part by weight of isopropyl alcohol, and 3 parts by weight of water with respect to 100 parts by weight of the water-absorbing fine particles. Mix the solution
By performing a heat treatment at 195 ° C., water-absorbing fine particles subjected to a surface cross-linking treatment as one form of the water-absorbing polymer were obtained.

In the above manufacturing apparatus, the transport belt 16
No adhesion of the hydrogel 19 to the rotating rolls 40 was observed, and the hydrogel 19 was smoothly conveyed. Also,
There were no scratches or cuts (cracks) on the hydrogel 19, especially on both ends. Furthermore, the water-containing gel 19 was not caught near the entrance of the gel crusher 21.

[Comparative Example 1] Water absorption was carried out in the same manner as in Example 1 except that the water 43 was not dropped from the water dropping devices 42 and 42 and the water 45 was not sprayed from the water spraying device 44. Production of fine particles was performed continuously.

In the above manufacturing apparatus, adhesion of the hydrogel 19 to the conveyor belt 16 was often observed, and it was difficult to separate the hydrogel 19 from the conveyor belt 16. More specifically, it was observed that the hydrogel 19 adhered to the inner surfaces 16a 'and 16a' of the side dams 16a and 16a, and a part thereof remained. For this reason, both ends of the hydrogel 19 peeled from the conveyor belt 16 are partially missing, and cracks or cuts therefrom. When the water-containing gel 19 is cut, the water-containing gel 19 is caught (clogged) between the rotating rolls 40 and near the entrance of the gel crusher 21.
Was often observed. In addition, the above hydrogel 19
However, since the adhesive easily adhered to the roll surface of the rotating rolls, smooth conveyance of the hydrogel 19 was often hindered.

Embodiment 2 Instead of spraying the water 45 from the water spraying device 44 in the above-described Embodiment 1, the inside of each rotating roll 40 (for example, the inside of the shaft of the rotating roll 40 formed in a tubular shape) is used. 5), cold water at 5 ° C. was flowed to generate condensation (water) of steam on the roll surface (support surface). Otherwise, the production of water-absorbing fine particles was continuously performed in the same manner as in Example 1 above.

In the manufacturing apparatus described above, adhesion of the hydrogel 19 to the conveyor belt (conveyor) 16 and the rotating rolls (conveyor) 40 was not observed, and the hydrogel 19 was smoothly conveyed. Further, no scratches or cuts (cracks) were generated on the hydrogel 19, particularly on both ends thereof. Furthermore, the hydrogel 19 is located near the entrance of the gel crusher 21,
There was no snag.

[Embodiment 3] In the first embodiment, the roll surface of each rotary roll 40 is covered with a moisturizing material, and the temperature inside each rotary roll 40 is controlled by a heating means (not shown).
C. to 80.degree. C., and the hydrogel 19 was heated while being transported by the rotating rolls 40. Otherwise, the production of water-absorbing fine particles was continuously performed in the same manner as in Example 1 above.

In the above-mentioned manufacturing apparatus, adhesion of the hydrogel 19 to the conveyor belt (conveying means) 16 and the rotating rolls (conveying means) 40 was not observed, and the hydrogel 19 was smoothly conveyed. Further, no scratches or cuts (cracks) were generated on the hydrogel 19, particularly on both ends thereof. Furthermore, the hydrogel 19 is located near the entrance of the gel crusher 21,
There was no snag.

Further, by heating the hydrogel 19 taken out of the polymerization machine 18, it was possible to prevent kneading when the hydrogel 19 was crushed by the gel crusher 21. Furthermore, since the aging proceeds by heating the hydrogel 19, residual monomers and soluble components in the finally produced water-absorbing fine particles are reduced as compared with conventional products.

[0084]

As described above, according to the method for transporting hydrogel according to the present invention, it is possible to prevent the hydrogel from sticking to the support surface of the transport means. In addition, it is possible to release the hydrogel once adhered to the support surface from the support surface. This prevents the occurrence of a cause that hinders the smooth transport of the hydrogel in the transport means.
Can be suppressed. As a result, there is an effect that it is possible to eliminate the possibility that the hydrogel is stretched during transportation and cracks or cuts.

When the transport means is a relatively movable transport means such as a guide roll, a rotating roll, a roller conveyor, etc., it is possible to prevent the hydrogel from sticking to the support surface of the transport means. Therefore, the hydrogel can be smoothly moved relative to the support surface.

When the above-mentioned conveying means is a relatively stopping type conveying means such as an endless belt, it is possible to prevent the hydrogel from sticking to the support surface of the conveying means. As a result, the hydrogel can be easily peeled off from the support surface, so that the hydrogel can be smoothly carried out of the transport means.

Further, when conveying a hydrogel having a portion having high tackiness, such as a hydrogel produced by static polymerization of a water-soluble ethylenically unsaturated monomer,
This has the effect of preventing or suppressing the occurrence of causes that hinder smooth transport.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an apparatus for producing a water-absorbing polymer to which the method for transporting a hydrogel according to the present invention is applied.

FIG. 2 is a front view of a conveyor belt provided in the polymerization machine as viewed from a conveyance direction side.

[Explanation of symbols]

 16 Conveying belt (conveying means; endless belt) 16a 'Inner surface (supporting surface) 19 Hydrous gel 40 Rotating roll (conveying means) 43 Water 45 Water

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koji Miyake 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo 1 Inside Nippon Shokubai Co., Ltd. 1 F-term in Nippon Shokubai Co., Ltd. (reference) 4J011 AA01 BA01 DA04 DB13 DB18 DB21 HA02 HB12 4J100 AJ02P AJ09P AK01P AL03P AL09P AM02P AM15P CA01 CA04 FA47 GC29 GC32 GC37 JA60

Claims (9)

[Claims] 1. A method for transporting a hydrogel, wherein the hydrogel is supported and transported by a support surface provided on a transport means, wherein the hydrogel is provided between the support surface and the hydrogel, and / or A step of supplying water to the vicinity of the region supported by the support surface, and a step of peeling the hydrogel out of the support surface and carrying it out of the conveying means. Transport method. 2. A method for transporting a hydrogel, wherein the hydrogel is supported by a support surface provided on a conveying means and is relatively moved with respect to the support surface, wherein the hydrogel is moved between the support surface and the hydrogel. And supplying water to the vicinity of the region of the hydrogel that is supported by the support surface. 3. A method for transporting a hydrogel, wherein the hydrogel obtained by statically polymerizing a water-soluble ethylenically unsaturated monomer on an endless belt is supported and transported by a support surface of the endless belt. A step of supplying water to the support surface, between the side end on the rear side in the transport direction of the hydrogel and the hydrogel, and / or in the vicinity of the side end on the rear side in the transport direction of the hydrogel, Peel the hydrogel from the endless belt,
Transporting the hydrogel out of the endless belt. 4. The water-containing gel according to claim 1, wherein the water is supplied as dew by setting the temperature of the support surface to be equal to or lower than the dew point of the atmosphere. Transport method. 5. A method of transporting a hydrogel by a transporting means, comprising a step of supplying water to the hydrogel and / or the transporting means. 6. A method for transporting a hydrogel, wherein the hydrogel is supported and transported by a roll provided in a transport means, comprising a step of supplying water to the hydrogel and / or the roll. Method for transporting hydrogel. 7. A method for transporting a hydrogel, comprising a step of supporting and transporting the hydrogel by a plurality of rolls provided in a transport means. 8. The method according to claim 1, wherein the hydrogel is obtained by static polymerization of a water-soluble ethylenically unsaturated monomer. The method for transporting a hydrogel according to claim 1. 9. The method according to claim 1, further comprising a step of heating the hydrogel conveyed by the conveying means. A method for conveying the hydrogel according to the above.