JP2001270948A - Method for transporting, storing and manufacturing granular water absorbing resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for handling a granular water absorbing resin with no or little deterioration of characteristics which permits stable pulverization, transfer and storage as well as prevention of contamination of aggregates of the granular resin during the manufacturing. SOLUTION: In transfer or storage of a granular water absorbing resin or in a pulverizing step in the manufacturing process, at least one of the following actions is taken; (1) heating from the outside at least a part of the wall surface with which the resin is contacted, (2) keeping at least a part of the inner wall surface at 30-150 deg.C of and (3) keeping at least a part of the surface not lower by at most 20 deg.C than that of the granular water absorbing resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for handling particulate water-absorbing resin. More specifically, the present invention relates to a method for producing a particulate water-absorbent resin, which includes a step of pulverizing the water-absorbent resin as part of all the steps, in addition to improvements in the transportation and storage during and after the production of the particulate water-absorbent resin. Regarding improvement of itself.
More specifically, a water-absorbent resin that has been applied to a wide range of applications as an absorbent for sanitary materials such as sanitary napkins and disposable diapers, or as a water retention agent and dehydrating agent in the fields of agriculture and horticulture and the civil engineering field, with high accuracy. The present invention relates to a method of pulverizing, transporting and storing with good productivity.

[0002]

2. Description of the Related Art Generally, a particulate water-absorbing resin has a particle size of 1 mm.
It is used in the form of a powder having a particle size of up to several tens μm. For this reason, the particulate water-absorbent resin is obtained by drying a hydrogel polymer obtained by polymerizing a hydrophilic monomer, and then pulverizing with a pulverizer such as a roll mill, a high-speed rotary pulverizer, and a jet pulverizer. Is manufactured. At the time of the above-mentioned pulverization, aggregates of the particulate water-absorbent resin adhere to the inside of the pulverizer or pipes near the outlet of the pulverizer, and clogging occurs, and a stable pulverization operation cannot be performed. Was sometimes mixed into the particulate water-absorbent resin to deteriorate the physical properties.

[0003] The particulate water-absorbing resin obtained above is then subjected to a classification step, a granulation step, a mixing step of additives and the like, a surface treatment step, and the like, and becomes a product. Low power mechanical or pneumatic (pn
eumatic) tied by transport. The particulate water-absorbent resin is also used at the stage after production, such as at the time of use,
May go through the transportation process. At the time of this production, in the transportation step after the production, aggregates of the particulate water-absorbent resin adhere to the transporter, and similarly to the above, clogging occurs and a stable transport operation cannot be performed, or aggregates are generated. In some cases, physical properties may be reduced by mixing with the particulate water-absorbing resin.

[0004] When the particulate water-absorbent resin is stored between the steps of the above-mentioned production, or when the final product is stored after the production, there are the same problems as described above. In the process of obtaining the particulate water-absorbent resin, the particulate water-absorbent resin is classified. At this time, the same problem as described above sometimes occurs. Therefore, the present inventors filed a method and an apparatus for classifying the particle size with high accuracy and high productivity by using the classifier in a heated state and / or a warm state in the classification of the particulate hydrophilic polymer. (Japanese Patent Laid-Open No. 10-202187, European Patent 855232). Further, the continuous granulation method of the water absorbent resin powder is disclosed in US Pat.
9148. In performing the continuous granulation method, in order to prevent a strongly sticky agglomerate consisting of solidified particles of the water-absorbent resin powder and the aqueous liquid from adhering to the cylindrical body, Heating the body. In contrast, the present invention described below relates to pulverization of a water-absorbent resin and transportation or storage of a particulate water-absorbent resin. Here, the intended water-absorbent resin or particulate water-absorbent resin is
There is no stickiness and there is fluidity. It is unpredictable that heating which has an adhesion preventing effect on highly sticky agglomerates has an effect on a non-sticky and fluid water-absorbent resin or a particulate water-absorbent resin.

[0005]

The problem to be solved by the present invention is that the above-mentioned pulverization in the method for producing a particulate water-absorbent resin can be carried out stably, During and after the production, the transportation and storage of the particulate water-absorbent resin can be performed stably, and the incorporation of aggregates of the particulate water-absorbent resin can be prevented. An object of the present invention is to provide a resin handling method.

[0006]

The present inventors have studied in detail the cause of the formation of the above-mentioned aggregates. As a result, the water-absorbent resin obtained by drying the hydrogel polymer is 3 to 1 times.
It has a water content of about 5%, and the heat generated during the pulverization evaporates the water, agglomerates the pulverized particulate water-absorbent resin, the inner wall surface of the pulverizer, the pulverizing member, and the outlet of the pulverizer. It became clear that it tended to adhere as aggregates in the vicinity. It was also found that when the particulate water-absorbent resin whose surface area was significantly increased by the pulverization was transported or stored, water was evaporated and aggregates were formed in the same manner as described above.

[0007] The inventors of the present invention used the pulverizer, transporter, or storage tank in a heated state or a heated state in order to suppress agglomeration due to moisture contained in the particulate water-absorbing resin. Was found to be improved, and the present invention was achieved. That is, the method for transporting the particulate water-absorbent resin according to the present invention is a method for transporting the particulate water-absorbent resin obtained by pulverizing a dried body of the water-absorbent resin. (1) heating at least a part of the surface in contact with the particulate water-absorbent resin from the outside; (2) setting the inner wall surface temperature of at least a part of the surface in contact with the particulate water-absorbent resin to 30 to 150 ° C
(3) at least one of keeping the inner wall surface temperature of at least a part of the surface in contact with the particulate water-absorbent resin from being 20 ° C. lower than the temperature of the particulate water-absorbent resin. Is performed.

The method for storing a particulate water-absorbent resin according to the present invention is a method for storing a particulate water-absorbent resin obtained by pulverizing a dried water-absorbent resin. Upon storage, (1) heating at least a part of the surface in contact with the particulate water-absorbent resin from the outside; and (2) an inner wall surface temperature of at least a part of the surface in contact with the particulate water-absorbent resin. (3) Keeping the inner wall surface temperature of at least a part of the surface in contact with the particulate water-absorbent resin from being lower than the temperature of the particulate water-absorbent resin by 20 ° C. , At least one of which is performed.

Further, the method for producing a particulate water-absorbent resin according to the present invention comprises, in a part of the entire process, a pulverization step of pulverizing a dried water-absorbent resin into a particulate water-absorbent resin. In the method for producing a water-absorbent resin, in the pulverizing step, (1) at least a part of a surface in contact with the particulate water-absorbent resin is heated from outside, and (2) the particulate water-absorbent resin is heated. (3) maintaining at least a part of the inner wall surface temperature of the contacting surface with the particulate water-absorbing resin at at least a part of the contacting surface; At least one of not to be lower than 20 ° C.

As described above, the present inventors have disclosed in Japanese Patent Application Laid-Open
It has been found that the method basically shown in EP 202187 (EP 855232) is also applicable in each of the steps of grinding, transporting and storing. Surprisingly, the transportation method and the storage method according to the above-mentioned improvement are also applied to the particulate water-absorbing resin in which the surface cross-linking treatment is applied and the water content is reduced.
It is preferably used.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Water-absorbent resin] As a dried water-absorbent resin used in the present invention, a water-soluble polymerizable unsaturated group-containing monomer such as (meth) acrylic acid, (anhydrous) Maleic acid, fumaric acid, crotonic acid, itaconic acid, 2- (meth) acryloylethanesulfonic acid, 2-
(Meth) acryloylpropanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid,
Anionic monomers such as vinyl sulfonic acid and styrene sulfonic acid, salts thereof, (meth) acrylamide, N-substituted (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, Methoxy polyethylene glycol (meta)
Nonionic hydrophilic group-containing monomers such as acrylate and polyethylene glycol (meth) acrylate, N, N-
Dimethylaminoethyl (meth) acrylate, N, N-
Dimethylaminopropyl (meth) acrylate, N, N
-An amino group-containing unsaturated monomer such as dimethylaminopropyl (meth) acrylamide, or a quaternary compound thereof;
A crosslinking agent that forms a crosslinked structure during polymerization, for example, a compound having two or more polymerizable unsaturated double bonds in the molecule, an acid group, a hydroxyl group, an amino group, etc. of a water-soluble unsaturated group-containing monomer A compound having two or more groups in the molecule that react with the functional group of the above, a compound having one or more groups in the molecule that respectively react with the unsaturated bond and the functional group of the monomer, A water-absorbent resin obtained by polymerizing a compound having two or more points that react with a group, or a hydrophilic polymer capable of forming a cross-linked structure by graft bonding or the like when a monomer component is polymerized, and drying. Dried product. Among these, a partially neutralized salt of a crosslinked polyacrylic acid is preferably used because of availability of raw materials.

The dried body of the water-absorbing resin used in the present invention is preferably a dried body dried at a temperature of 160 to 250 ° C. The particulate water-absorbent resin targeted by the present invention is obtained by pulverizing the dried product, and is generally commercially available as a dry pulverized product.
m or less. In the present invention, the shape of the particulate water-absorbing resin includes a spherical shape, a cubic shape, a columnar shape, a plate shape, a phosphorus shape, a rod shape, a needle shape, a fiber shape, and an irregular shape. The particle size of the particulate water absorbent resin is usually 1
000 μm or less, preferably 850 μm or less.

The particulate water-absorbent resin targeted by the present invention is:
Generally, it is a powder having fluidity. It is preferable that the particulate water-absorbent resin has been subjected to a surface crosslinking treatment. The surface cross-linking treatment technology is described in, for example,
7-44627, JP-A-58-42602, JP-B-60-18690, JP-A-58-180233, JP-A-59-62665, JP-A-61-16903,
JP-A-4-246403, U.S. Pat. No. 5,422,405
No. 5,597,873, European Patent 450923
No., European Patent 450924, WO99 / 42494,
WO 99/42496, WO 99/43720 and the like. Especially, it is suitably applied to those subjected to surface cross-linking treatment using a polyhydric alcohol as at least one of the surface cross-linking treatment components. In this case, a part of the polyhydric alcohol used is often left to impart hydrophilicity. The polyhydric alcohol is used as an auxiliary agent, and the surface crosslinking agent is a substance other than the polyhydric alcohol, and is suitably applied to a particulate water-absorbing resin produced by a surface crosslinking treatment.

[Definition of Heating and Heat Insulation] In the present invention, “heating” means to actively apply heat. Therefore, the "heated state"
When heat is applied from the outside to the inner wall of a device such as a crusher, transporter or storage tank to raise the temperature to a certain temperature, and then no heat is applied. And the case where heat is applied from the outside. On the other hand, "heat retention" refers to making it difficult for heat to escape without giving heat, that is, making it difficult to lower the temperature. Therefore, the “heat-retained state” refers to a case where heat is not applied and heat is hardly released by winding a heat insulating material around the device. In the present invention, the "heated state" and the "heat-retained state" may be used in some cases. In some cases, a heat insulating material may be used while actively applying heat from the outside.

In order to heat or keep the inner wall surface of a device such as a pulverizer, transporter or storage tank from the outside, a device provided with a means for heating the inner wall surface from outside or a device for keeping the temperature warm is used. Or raising the ambient temperature where the device is placed. As a device having a heating means and a means for keeping the temperature, for example, as a means for heating a conventionally known device such as a crusher, a transporter or a storage tank, a tape-shaped heating element provided with a jacket that can be heated by electricity or steam, It can be easily manufactured by winding, for example, or by winding a heat insulating material (heat insulating material) as a means for keeping the temperature. Of course, two or more of these may be used in combination.

The heat insulating material (heat insulating material) that can be used in the present invention is not particularly limited. For example, fibrous heat insulating materials such as asbestos heat insulating material, rock wool heat insulating material, glass wool heat insulating material, and heat resistant inorganic fiber heat insulating material; Powdered heat insulators such as calcium oxide heat insulator and aqueous pearlite heat insulator; foamed heat insulators such as polystyrene foam heat insulator, hard urethane foam heat insulator, and foamed glass insulator; metal foil heat insulator, paper honeycomb, etc. An air layer heat insulating material or the like can be used. As the particle size of the particulate water-absorbent resin becomes smaller, the particulate water-absorbent resins tend to adhere to each other to form aggregates. Therefore, the handling method of the present invention is used for handling the particulate water-absorbent resin including the water-absorbent resin particles having a particle diameter of less than 150 μm,
More preferably applicable.

[Pulverizing Step] The method for producing a particulate water-absorbent resin according to the present invention is, for example, one obtained by polymerizing a hydrophilic monomer. After drying, and pulverizing with a pulverizer to obtain a particulate water-absorbing resin. Examples of the pulverizer used in the pulverization step include a roller mill, a knife mill, a hammer mill, a pin mill, a jet mill and the like, and have a means for heating the inner wall surface of the pulverizer itself. In the pulverizing step, the inner wall surface of the pulverizer is heated from the outside, the inner wall surface temperature of the pulverizer is set to 30 ° C. to 150 ° C., or the inner wall surface temperature of the pulverizer is a particulate water absorbent resin. 20 ° C. must not be lower than the temperature of In other words, by adjusting the temperature of the inner wall surface of the pulverizer that comes into contact with the particulate water-absorbent resin to such an extent that the coagulation of the particulate water-absorbent resin does not occur, the coagulation in the pulverizer and near the outlet thereof is effective. Can be prevented. In addition, the particulate water-absorbent resin obtained by the pulverization adheres to the inner side wall of the pulverizer, and further forms a large aggregate, and the agglomerate peels off due to the vibration of the pulverizer and is mixed into the product. Can be prevented.

The inner wall temperature of the crusher is preferably 30 to
The temperature is adjusted to 150 ° C, more preferably 40 to 90 ° C, most preferably 50 to 80 ° C. When the inner wall surface temperature is lower than 30 ° C., the effect of the present invention cannot be obtained. On the other hand, even when the temperature exceeds 150 ° C., the effect obtained at 150 ° C. or lower is not changed. Not only is it disadvantageous, but also undesirable for the device. The inner wall temperature of the pulverizer is preferably 2 to the temperature of the particulate water absorbent resin.
The temperature is adjusted so that 0 ° C. does not decrease, more preferably 10 ° C. does not decrease. The temperature of the particulate water-absorbent resin, when handling the particulate water-absorbent resin on an industrial scale,
In order to ensure the fluidity, a temperature of room temperature or higher, for example, about 40 to 150 ° C, more preferably 50 to 80 ° C
It may be adjusted to the extent. When the inner wall surface temperature of the crusher is lower than 20 ° C. with respect to the temperature of the particulate water absorbent resin, the heated particulate water absorbent resin is cooled on the inner wall surface of the crusher, The agglomerates adhere to the inner wall surface of the crusher, and further form large agglomerates, and the vibrations of the crusher may cause the agglomerates to peel off and enter the product.

The pulverizer used in the present invention is provided with the above-described heating means, and can be effectively used in the pulverizing step of the water absorbent resin. [Transportation step] The transportation method according to the present invention is a method including a step of transporting the dried particulate water-absorbent resin using a transporter during or after the production of the particulate water-absorbent resin. Examples of the transporting machine used in the transporting step include a belt conveyor, a screw conveyor, a chain conveyor, a vibration conveyor, a pneumatic conveyor, and the like, provided with a means for heating the inner wall surface from the outside and / or a means for keeping the temperature warm. Things can be mentioned.
Among these transporters, a chain conveyor or a pneumatic conveyor is preferred.

In this transportation step, the inner wall surface of the transporter is heated and / or kept warm from the outside, the inner wall surface temperature of the transporter is set at 30 ° C. to 100 ° C., or It is essential that the inner wall surface temperature is not lower than the temperature of the particulate water absorbent resin by 20 ° C. That is, by adjusting the temperature of the inner wall surface of the transporter that comes into contact with the particulate water-absorbent resin to such an extent that aggregation of the particulate water-absorbent resin does not occur, it is possible to effectively prevent aggregation in the transporter. Also, it prevents the particulate water-absorbing resin from adhering to the inner side wall of the transporter during transportation, forming large aggregates, and the aggregates peeling off due to the vibration of the transporter and mixing into the product. it can.

The temperature of the inner wall surface of the transport machine is preferably 30 to
The temperature is adjusted to 150 ° C, more preferably 40 to 90 ° C, most preferably 50 to 80 ° C. When the inner wall surface temperature is lower than 30 ° C., the effect of the present invention cannot be obtained. On the other hand, even when the temperature exceeds 150 ° C., the effect obtained at 150 ° C. or lower is not changed. Disadvantageous.
The inner wall surface temperature of the transporter is adjusted so as not to lower preferably by 20 ° C., more preferably not by 10 ° C., with respect to the temperature of the particulate water-absorbing resin. The temperature of the particulate water-absorbent resin is, when handling the particulate water-absorbent resin on an industrial scale, in order to secure its fluidity, at a temperature of room temperature or higher, for example, about 40 to 100 ° C, more preferably 50 to 100 ° C. It may be adjusted to about 80 ° C. The temperature of the inner wall surface of the transporter is 20 with respect to the temperature of the particulate water absorbent resin.
When the temperature is lower than ℃, the particulate water-absorbent resin in a heated state is cooled on the inner wall surface of the transporter, so that aggregates adhere to the inner wall surface of the transporter, and further, large aggregates are formed. Formed, the aggregates may peel off due to the vibration of the transporter and mix into the product. In addition, the particulate water-absorbent resin may be exposed to a state where it is easily subjected to a shearing force due to transportation, and performance may be reduced.

The physical properties of the particulate water-absorbing resin should not be changed by heating and keeping the temperature, and the heating / heating should be considered in consideration of the type of the particulate water-absorbing resin to be applied, the residence time in the transport machine, and the like. It is necessary to choose the temperature of the heat retention. The transportation method according to the present invention can be used in a factory for producing particulate water-absorbent resin, and when the water-absorbent resin is used for various purposes, for example, a factory for producing sanitary materials such as disposable diapers and sanitary articles. Can also be suitably used. Since it is a loss to reduce the performance of the particulate water-absorbent resin whose absorption capacity under pressure has been improved by the surface cross-linking treatment due to inadequate handling, the present transport method has such an absorption capacity under pressure of 18 g / g or more. , More preferably 21 g / g or more.

[Storage step] The storage method according to the present invention comprises:
This method comprises a step of storing the dried particulate water absorbent resin in a storage tank during or after the production of the particulate water absorbent resin. The storage tank used in this storage step includes, for example, a silo, a hopper, etc., provided with a means for heating the inner wall surface thereof. In the case of the particulate water-absorbent resin, a storage tank having a metallic inner surface, for example, an inner surface made of iron or stainless steel, is preferable in view of the abrasion and charging properties of the particulate water-absorbent resin. In this storage step, the inner wall surface of the storage tank is heated from the outside, the inner wall surface temperature of the storage tank is set to 30 ° C. to 150 ° C., or the inner wall surface temperature of the storage tank is set to the temperature of the particulate water absorbent resin. On the other hand, it is essential that the temperature is not lowered at 20 ° C. That is, by adjusting the temperature of the inner wall surface of the storage tank in contact with the particulate water-absorbent resin to such an extent that the aggregation of the particulate water-absorbent resin does not occur, the aggregation in the storage tank can be effectively prevented. Further, it is possible to prevent the particulate water-absorbing resin from adhering to the inner side wall of the storage tank and forming a large aggregate, and the aggregate is peeled off due to vibration of the storage tank or the like and mixed into the product.

The inner wall surface temperature of the storage tank is preferably 30 to 1
The temperature is adjusted to 50 ° C, more preferably 40 to 90 ° C, most preferably 50 to 80 ° C. When the inner wall surface temperature is lower than 30 ° C., the effect of the present invention cannot be obtained. On the other hand, even when the temperature exceeds 150 ° C., the effect obtained at 150 ° C. or lower is not changed. Disadvantageous.
The inner wall surface temperature of the storage tank, with respect to the temperature of the particulate water absorbent resin,
Preferably, the temperature is adjusted so that 20 ° C. does not decrease, and more preferably 10 ° C. does not decrease. The temperature of the particulate water-absorbent resin is, when handling the particulate water-absorbent resin on an industrial scale, in order to ensure its fluidity, a temperature of room temperature or higher, for example, about 40 to 150 ° C, more preferably 50 to 150 ° C. It may be adjusted to about 80 ° C. If the temperature of the inner wall surface of the storage tank is lower than 20 ° C. with respect to the temperature of the particulate water-absorbent resin, the heated particulate water-absorbent resin is cooled on the inner wall surface of the storage tank. Adhere to the inner wall surface of the storage tank and form large aggregates, and the aggregates may peel off due to vibration of the storage tank and be mixed into the product. Further, the particulate water-absorbing resin may be exposed to a state where it is easily subjected to a shearing force accompanying the discharge from the storage tank, and the performance may be deteriorated.

It should be noted that changes in the physical properties of the particulate water-absorbent resin due to heating and heat retention should be avoided. Considering the type of the particulate water-absorbent resin to be applied and the residence time in the storage tank, etc. It is necessary to choose the temperature of the heat retention.
This storage step can be used in a factory that produces particulate water-absorbent resin, and when the water-absorbent resin is used for various purposes, for example, it is also suitable in a factory that manufactures sanitary materials such as disposable diapers and sanitary products. Can be used. Since it is a loss to reduce the performance of the particulate water-absorbent resin whose absorption capacity under pressure has been improved by the surface cross-linking treatment due to inadequate handling, the present storage method has such an absorption capacity under pressure of 18 g / g or more. , More preferably 21 g / g or more.

[0026]

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. In addition, the various physical properties of the water-absorbent resin were measured by the following methods. (1) Water absorption 0.2 g of a water-absorbent resin in a tea bag type bag (6 cm x 6 c
m), heat-sealing the opening,
It was immersed in a 9% by weight aqueous solution of sodium chloride (physiological saline). After 60 minutes, the tea bag-type bag was lifted, and after draining at 250 cm / sec ² (250 G) for 3 minutes using a centrifuge, the weight W1 (g) of the bag was measured. In addition, the same operation is performed without using a water absorbent resin,
The weight W0 (g) at that time was measured. Then, the water absorption was calculated from the weights W1 and W0 according to the following equation a.

Formula a: Water absorption (g / g) = (W1−W0) / weight of water absorbing resin (g) (2) Water soluble content 0.5 g of water absorbing resin is dispersed in 1000 ml of deionized water. After stirring for 16 hours, the swollen gel was filtered with filter paper. Then, the water-soluble polymer in the obtained filtrate was titrated by colloid titration, and the result was determined. The water-soluble content is expressed in terms of% by weight of the water-absorbent resin. (3) The absorption capacity under pressure is 4.9 kPa (50 kPa).
g / cm ² ), calculated from the amount of physiological saline absorbed for 60 minutes. Details of the measuring method are described in JP-A-11-30.
2391 (EP 855232).

Example 1 Aqueous polymerization of a partial sodium salt of acrylic acid neutralized at 75 mol% and trimethylolpropane triacrylate was carried out, and the resulting water-absorbent resin hydrogel was crushed into particles. This was spread thinly on a perforated plate of a band dryer, and dried at 180 ° C. with hot air. A dried product 3 aggregated at the outlet of the dryer was obtained. This dried body 3
At 100 kg / h to a roll crusher (manufactured by Asano Iron Works) 1 shown in FIG.
Thus, a particulate water absorbent resin 4 was obtained. The roll crusher 1 includes an outer frame 12 having an inlet 11 and a pair of rolls 21 and 22 installed in the outer frame 12. A steam tress 13 is wound around the entire outer frame 12. The upper part is further covered with a thermo-insulating thermo mat (not shown). The dried body 3 obtained by crushing is supplied between the rolls 21 and 22 from above through the inlet 11 of the outer frame 12. Steam is 0.2
MPa. The temperature of the inner wall surface of the outer frame of the roll mill is 7
5 ° C. No trouble occurred during the grinding operation for 8 hours.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the roll crusher without steam tress and heat insulating material was used and the temperature of the inner wall surface of the outer frame of the roll crusher was 25 ° C. The operation was performed. Two hours after the commencement of the pulverization, the pulverizer began to make an abnormal noise, and agglomerated particles began to mix in the particulate water-absorbent resin obtained at the pulverizer outlet. (Example 2) The powder of the particulate water-absorbing resin 4 at about 60 ° C obtained in Example 1 was transported over a distance of 10 m by a bucket conveyor 5 shown in FIG. The bucket conveyor 5 includes a chain 51 having buckets 52 attached at equal intervals,
A steam tress 53 is provided to cover them, and the steam tress 53 is further covered with a heat insulating material (not shown).
In the bucket conveyor 5, the bucket 52 moves with the movement of the chain 51. Adjust the temperature of the inner wall surface of the steam tress 53 to 60 ° C and transport 10 times.
After a period of time, no aggregate of the particulate water-absorbent resin 4 was formed during transportation.

(Comparative Example 2) Transportation was carried out for about 9 hours in the same manner as in Example 2 except that steam was not passed through the steam tress. As the amount of material attached to the inside of the bucket increased over time, the load on the chain drive motor increased, and when about 9 hours had elapsed, it was determined that the motor would burn if continued operation was continued. . (Example 3) The powder of the particulate water-absorbent resin 4 at about 60 ° C obtained in Example 1 was classified by a sieving apparatus having a mesh opening of 850 μm and a screen of 150 μm and covered with a heat insulating material, A particulate water-absorbing resin 4 (No. 1) having a size of 850 μm or less and 150 μm or more was obtained. The physical properties (average value) of the particulate water-absorbent resin 4 (No. 1) were as follows. Water absorption 50 g / g, water soluble content 20 wt% 14 mesh (1180 μm) on 0% 20 mesh (850 μm) on 0% 100 mesh (150 μm) on 98% 100 mesh (150 μm) pass 2% This particulate water absorption Resin 4 (No. 1) was charged into hopper 7 shown in FIG. The hopper 7 is provided with an outer frame 72, an inlet 73, an outlet 74, a jacket 75 covering the outer frame, an electric heater 76, and a bag filter (not shown). The structure is such that the entire body is kept warm and the inner wall surface temperature of the outer frame 72 is kept at 60 ° C. The electric heater 7 is located near the outlet 74.
6 is further heated. The hopper 7 is filled with about 10 tons of the particulate water-absorbent resin 4, and one day later, while extracting the particulate water-absorbent resin 4 from the outlet 74 (the powder temperature at the time of extraction was about 52 ° C.), 2
An operation of filling the paper bags in 0 kg units was performed. This extraction was smooth and the physical properties (average value) of the particulate water absorbent resin 4 (No. 2) filled in the paper bag.
Was as follows. Water absorption: 50 g / g, water soluble content: 20% by weight 14 mesh (1180 μm) on 0% 20 mesh (850 μm) on 0% 100 mesh (150 μm) on 98% 100 mesh (150 μm) Pass 2% (Comparative Example 3) When the same operation as in Example 3 was performed in Example 3 except that hot water and an electric heater were not used, the particulate water-absorbent resin 4 did not come out during the extraction operation. This is presumed that a bridge has occurred inside the hopper 7. Agglomerates were found in the particulate water-absorbent resin 4 (No. 3) filled in the paper bag.

The physical properties (average value) of the particulate water absorbent resin 4 (No. 3) were as follows. Water absorption 49g / g, water soluble content 19% by weight 14 mesh (1180μm) on 2% 20 mesh (850μm) on 3% 100 mesh (150μm) on 94% 100 mesh (150μm) pass 1% (Example 4) Water absorbent resin 4 of Example 3 (No. 2) 1
After mixing with a high-speed stirrer 03 parts by weight of a crosslinking agent aqueous solution consisting of 0.03 parts by weight of ethylene glycol diglycidyl ether / 1 part by weight of propylene glycol / 3 parts by weight of water / 1 part by weight of isopropyl alcohol with respect to 00 parts by weight,
Heat treatment was continuously performed using a paddle dryer. The material temperature at the dryer outlet was around 195 ° C. Physical properties (average value) of obtained water-absorbent resin 4 (No. 4) were as follows. Water absorption 34 g / g, water soluble content 18 wt% 14 mesh (1180 μm) on 0% 20 mesh (850 μm) on 0% 100 mesh (150 μm) on 97% 100 mesh (150 μm) pass 3% Absorption capacity under pressure 24 g / G (Example 5) The powder of the particulate water-absorbent resin 4 (No. 4) at about 60 ° C obtained in Example 4 was transported by the bucket conveyor 5 shown in FIG. The transport was performed for 10 hours while adjusting the inner wall surface temperature of the steam tress 53 to 60 ° C., but no aggregate of the particulate water-absorbent resin 4 (No. 4) was generated during the transport. Physical properties (average value) of the transported particulate water-absorbent resin 4 (No. 5) were as follows. Water absorption 34 g / g, water soluble content 18 wt% 14 mesh (1180 μm) on 0% 20 mesh (850 μm) on 0% 100 mesh (150 μm) on 97% 100 mesh (150 μm) pass 3% Absorption capacity under pressure 24 g / G (Comparative Example 5) Transportation was carried out for about 10 hours in the same manner as in Example 5, except that the steam was not passed through the steam tress. As the amount of material adhered to the inside of the bucket increased over time, the load on the chain drive motor increased, and when about 10 hours had elapsed, it was determined that the motor would burn if continued operation was continued. . 9
The particulate water absorbent resin 4 (N
o. The physical property values (average values) of 6) were as follows. Water absorption 32g / g, water soluble content 17% by weight 14 mesh (1180μm) on 1% 20 mesh (850μm) on 3% 100 mesh (150μm) on 94% 100 mesh (150μm) pass 2% Absorption capacity under pressure 21g / G (Example 6) About 10 tons of the particulate water-absorbent resin 4 (No. 5) was filled in the hopper 7 shown in FIG. Water absorbent resin 4
While extracting the powder (the powder temperature at the time of extraction was about 50 ° C.), the paper bag was filled with 20 kg each. This extraction was smooth and the physical properties (average value) of the particulate water-absorbent resin 4 (No. 7) filled in the paper bag were as follows. Water absorption 34g / g, water soluble content 18% by weight 14 mesh (1180μm) on 0% 20 mesh (850μm) on 0% 100 mesh (150μm) on 97% 100 mesh (150μm) pass 3% Absorption capacity under pressure 24g / G (Comparative Example 6) A paper bag was filled in the same manner as in Example 6 except that hot water in the jacket 75 was extracted and electricity was not passed through the electric heater 76 in Example 6. The physical properties (average value) of the particulate water-absorbent resin 4 (No. 8) sampled from the bag in the vicinity of the last filled bag among the 10 tons were as follows. Water absorption 34 g / g, water soluble content 18 wt% 14 mesh (1180 μm) on 1% 20 mesh (850 μm) on 3% 100 mesh (150 μm) on 94% 100 mesh (150 μm) pass 2% Absorption capacity under pressure 22 g / G (Example 7) Exhaust containing fine powder from the roll crusher of Example 1 is sucked into a bag filter through piping (not shown). The fine powder is being pneumatically transported to the bag filter. This pipe (about 8c inside diameter)
m), the pulverizing operation of Example 1 was performed while keeping the pipe temperature at about 70 ° C., and the operation was performed without any trouble for 4 days.

Comparative Example 7 The procedure of Example 7 was repeated, except that the steam was not passed through the steam tress. After about 50 hours, the exhaust became insufficient and the fine powder leaked out of the apparatus, and the operation was interrupted. When the piping was inspected, a large amount of fine water-absorbing resin adhered inside.

[0033]

According to the method of the present invention, the pulverization of the water-absorbent resin, the transportation or storage of the particulate water-absorbent resin can be performed stably, and the incorporation of aggregates of the particulate water-absorbent resin can be prevented. There is no or little deterioration in physical properties.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a crusher used in the present invention.

FIG. 2 is a diagram showing one embodiment of a transport machine used in the present invention.

FIG. 3 is a view showing one embodiment of a storage tank used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roll crusher 12 Outer frame 13 Steam tress 3 Dry body 4 Particulate water absorbent resin 5 Bucket conveyor 51 Chain 52 Bucket 53 Steam tress 7 Hopper 72 Outer frame 75 Jacket 76 Electric heater

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 7, 2001 (2001.6.7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

[0026]

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. In addition, the various physical properties of the water-absorbent resin were measured by the following methods. (1) Water absorption 0.2 g of a water-absorbent resin in a tea bag type bag (6 cm x 6 c
m), heat-sealing the opening,
It was immersed in a 9% by weight aqueous solution of sodium chloride (physiological saline). After 60 minutes, the tea bag-type bag was lifted up, drained at 250 × 9.81 m / s ² (250 G) for 3 minutes using a centrifuge, and then the weight W1 (g) of the bag was measured. The same operation was performed without using a water-absorbing resin, and the weight W0 (g) at that time was measured. Then, the water absorption was calculated from the weights W1 and W0 according to the following equation a.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takumi Hatsuda Nippon Shokubai Co., Ltd. 1 at 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo. F term in Nippon Shokubai (reference) 4F070 AA29 AB13 DA43 DA46 DA47 DA48 DB01 DB06 DC16

Claims (15)

[Claims] 1. A method for transporting a particulate water-absorbent resin obtained by pulverizing a dried body of a water-absorbent resin, wherein (1) contacting the particulate water-absorbent resin with the transport of the particulate water-absorbent resin Heating at least a part of the surface from the outside; (2) adjusting the inner wall surface temperature of at least a part of the surface in contact with the particulate water-absorbent resin to 30 to
(3) keeping at least a part of the inner wall surface temperature of the surface in contact with the particulate water absorbent resin not to be lower than the temperature of the particulate water absorbent resin by 20 ° C. A method for transporting a particulate water-absorbent resin, wherein one is performed. 2. The method for transporting a particulate water-absorbent resin according to claim 1, wherein the particulate water-absorbent resin is a surface-crosslinked particulate water-absorbent resin. 3. The method for transporting a particulate water-absorbent resin according to claim 2, wherein the surface-treated particulate water-absorbent resin contains at least a polyhydric alcohol. 4. The method for transporting a particulate water-absorbent resin according to claim 2, wherein the surface-crosslinked particulate water-absorbent resin has an absorption capacity under pressure of 18 g / g or more. 5. The method for transporting a particulate water-absorbent resin according to claim 1, wherein the particulate water-absorbent resin is a partially neutralized salt of a crosslinked polyacrylic acid. 6. The dried product of the water-absorbent resin is used at a temperature of 160.degree.
The method for transporting a particulate water-absorbing resin according to any one of claims 1 to 5, wherein the method is a dried body dried at a temperature of ° C. 7. A method for storing a particulate water-absorbent resin obtained by pulverizing a dried body of a water-absorbent resin, comprising: (1) contacting the particulate water-absorbent resin with the storage of the particulate water-absorbent resin; Heating at least a part of the surface from the outside; (2) adjusting the inner wall surface temperature of at least a part of the surface in contact with the particulate water-absorbent resin to 30 to
(3) keeping at least a part of the inner wall surface temperature of the surface in contact with the particulate water absorbent resin not to be lower than the temperature of the particulate water absorbent resin by 20 ° C. A method for storing a particulate water-absorbent resin, wherein one is performed. 8. The method for storing a particulate water-absorbent resin according to claim 7, wherein the particulate water-absorbent resin is a surface-crosslinked particulate water-absorbent resin. 9. The method for storing a particulate water-absorbent resin according to claim 8, wherein the surface-treated particulate water-absorbent resin contains at least a polyhydric alcohol. 10. The method for storing a particulate water-absorbent resin according to claim 8, wherein the surface-crosslinked particulate water-absorbent resin has an absorption capacity under pressure of 18 g / g or more. 11. The method according to claim 7, wherein the particulate water-absorbent resin is a partially neutralized salt of a crosslinked polyacrylic acid. 12. The dried product of a water-absorbent resin is used at 160 ° C. to 25 ° C.
7. A dried product which is dried at a temperature of 0 ° C.
2. The method for storing a particulate water-absorbent resin according to any one of 1 to 1. 13. A method for producing a particulate water-absorbent resin, comprising a pulverizing step of pulverizing a dried water-absorbent resin into a particulate water-absorbent resin as a part of all the steps. (1) heating at least a part of the surface in contact with the particulate water-absorbent resin from the outside; (2) setting the inner wall surface temperature of at least a part of the surface in contact with the particulate water-absorbent resin to 30 (3) keeping the temperature of the inner wall surface of at least a part of the surface in contact with the particulate water-absorbent resin not lower than the temperature of the particulate water-absorbent resin by 20 ° C. A method for producing a particulate water-absorbent resin, wherein at least one is performed. 14. The method for producing a particulate water absorbent resin according to claim 13, wherein the particulate water absorbent resin is a partially neutralized salt of a crosslinked polyacrylic acid. 15. The dried product of a water-absorbent resin is used at a temperature of 160 ° C. to 25 ° C.
The method for producing a particulate water-absorbent resin according to claim 13 or 14, which is a dried body dried at a temperature of 0 ° C.