JPH11156299A - Method for classifying granular hydrophilic polymer and sieve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for classifying granular hydrophilic polymers and a sieve by which the polymers having minute diameters are efficiently classified, and the inherent separative power of the sieve is exhibited. SOLUTION: In the classifying method of granular hydrophilic polymers, the granular hydrophilic polymer is kept at 30-100 deg.C, the contact angle to water of the contact surfaces between the polymer and sieve other than the screen net surfaces is kept at >=60 deg., and the material has >=70 deg.C heat distortion temp. In the sieve, the contact angle to water of the contact surfaces between the grain and sieve except the screen net surfaces is controlled to >=60 deg., and the material of the sieve has >=70 deg.C heat distortion temp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for classifying a particulate hydrophilic polymer and a sieving apparatus. More specifically, as a water-soluble polymer suitably used as a flocculant, a coagulant, a soil conditioner, a soil stabilizer, a thickener, etc., or as an absorbent for sanitary materials such as sanitary napkins, disposable diapers, or agriculture and horticulture. In the field of application and civil engineering, water-retaining agents, dewatering agents, etc., are suitable for wide-ranging applications such as water-absorbent resins, which are widely used as water-absorbing resins, with high accuracy and high productivity. It relates to a sieving device.

[0002]

2. Description of the Related Art Generally, dry classification such as air classification or sieving is employed in the classification operation of powder and granules. For example, air classification is said to be suitable for classifying small powders of 300 μm or less, but there is a problem that a large apparatus is required for air classification. On the other hand, sieving requires only a device that is more compact than air classification,
There are problems that the classification efficiency is low and the classification ability is low when classifying small powders having a size of 00 μm or less.

[0003] Above all, when sieving is performed by a conventional method when classifying a particulate hydrophilic polymer, the screen surface of the sieve may be closed by a short operation, and the classification efficiency and the classification capacity may be reduced. Further, when the separation particle size is as small as 300 μm or less, there is a problem that a product having a large particle size is mixed in a product having a fine particle size which has passed through a sieve mesh surface. In particular, Algaia (Al
lgaier) Tumbler lid (Tumbler-
A sieving device that moves a sieving mesh surface in a helical manner, such as a screening machine, has a high classification ability and is effective for classifying fine particles. However, there is a problem that the inherently high classifying ability cannot be exhibited.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for efficiently classifying particles with a fine separation particle diameter and a particle-like hydrophilic particle capable of exhibiting the inherent classification ability of a sieving apparatus. An object of the present invention is to provide a method for classifying a conductive polymer and a sieving apparatus.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on the causes of the above-mentioned problems in the classification of particulate hydrophilic polymers, particularly those having a small separation particle diameter, and as a result, have found that they It has been found that agglomerates are formed before and after the particles pass through the sieve mesh surface due to the moisture contained in the conductive polymer. That is, the particulate hydrophilic polymer that has passed through the sieve mesh surface adheres to the inner wall surface of the sieving device due to moisture, and further forms a large aggregate, and the aggregate is peeled off by the vibration of the sieving device. Particles having a particle size larger than the separated particle size are mixed into the product. In addition, if agglomeration occurs before passing through the sieve mesh surface, it may cause clogging of the sieve mesh surface.

[0006] In view of the above, the present inventors have studied the temperature of the particulate hydrophilic polymer and the surface of the contact surface between the particulate hydrophilic polymer and the sieving device in order to suppress aggregation due to moisture contained in the particulate hydrophilic polymer. As a result of examining the material, it was found that the above problems were improved, and the present invention was reached.

That is, the present invention relates to a method for dry particle classification of a particulate hydrophilic polymer using a sieving apparatus, wherein the temperature of the particulate hydrophilic polymer is 30 to 100 ° C. At least a part of the surface where the particulate hydrophilic polymer and the sieving device are in contact with each other is a material having a contact angle with water of 60 ° or more and a heat deformation temperature of 70 ° C or more. A method for classifying a hydrophilic polymer, and a device for dry particle size classification by sieving particles, wherein at least a part of the surface where the particles and the sieving device are in contact other than the sieve mesh surface has a contact angle with water of 60 degrees or more. And a material having a heat distortion temperature of 70 ° C. or more.

According to the present invention, the sieving apparatus is preferably used in the range of 45 μm
This is effective when a screen having a sieve mesh opening of 300 μm is used.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

In the present invention, the particulate hydrophilic polymer includes a water-soluble polymerizable unsaturated group-containing monomer such as (meth) acrylic acid, (anhydride) maleic acid, fumaric acid, crotonic acid, itaconic acid. And anionic monomers such as 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid and styrenesulfonic acid And its salts, (meth) acrylamide, N-substituted (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, Nonionic hydrophilic group-containing monomers such as N, N-di Amino group-containing unsaturated monomers such as tylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, and quaternized products thereof; And a water-soluble polymer obtained by polymerizing a dried and pulverized product, and the water-soluble polymerizable unsaturated group-containing monomer, and a crosslinking agent that forms a crosslinked structure during polymerization, for example, a polymerizable unsaturated compound in the molecule. Compounds having two or more double bonds, compounds having two or more groups in a molecule that react with functional groups such as an acid group, a hydroxyl group, and an amino group of a water-soluble unsaturated group-containing monomer, A compound having at least one group that reacts with an unsaturated bond and a functional group of a monomer, a compound having two or more points that react with a functional group of a monomer in a molecule,
Alternatively, a dry and pulverized water-absorbent resin obtained by polymerizing a hydrophilic polymer or the like capable of forming a crosslinked structure by graft bonding or the like when a monomer component is polymerized may be used. These particulate hydrophilic polymers are generally commercially available as dry and pulverized products, and usually have a particle size of 1000 μm or less. In the present invention, the particle shape may be any shape particle, and examples include 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 diameter of the particles in the present invention is 1000
μm or less, preferably 850 μm or less.

The present invention relates to a particle size classification in a classification operation, that is, an operation of dividing a granular material into two or more particle groups according to a particle diameter, and performs classification without using a solvent therein. It relates to dry classification. Dry classification mainly includes air classification and sieving. The present invention relates to a classification operation using a sieving apparatus having a sieve mesh surface.

The sieving apparatus used in the present invention is not particularly limited as long as it has a sieving screen, and examples thereof include those classified into a vibrating screen and a shifter. The vibrating screen includes an inclined type, a low-head type, a Hum-mer, a Raven,
Tylock (Ty-Rock), Gyrex (Gy)
rex), elliptical vibration (Eliptex), etc., and the shifter is Reciprocatin.
g) Form, Exolon-grader, Travers
Attor-sieb, Sauer-meyer, Gyratory shifter (Gyratory), Gyro shifter, and Lotex screen (Ro-tex). These are the movement shapes of the mesh surface: circle, ellipse, straight line, arc, pseudo-ellipse, spiral, vibration method: free vibration, forced vibration, driving method: eccentric shaft, unbalanced weight, electromagnet, impact, inclination of mesh surface : Horizontal type, inclined type, installation method: It is subdivided into floor type, hanging type, etc. Among them, Tumbler-Screening lid of Allgaier company
helical mesh surface by a combination of radial inclination (inclination of a sieve mesh that disperses material from the center to the periphery) and tangential inclination (inclination of a sieve mesh that controls the discharge speed on the mesh), as in “machines”. The moving sieving apparatus is very effective for classifying relatively fine particles.However, when this is used for classifying a particulate hydrophilic polymer, the problems such as the agglomeration described above are remarkable and the original classifying ability is exhibited. Can not. Therefore, it is extremely effective to apply the present invention. By applying the present invention to a sieving device such as a tan brush lid, it is possible to exhibit the characteristic that the tan brush lid is effective in classifying relatively fine particles inherent in the tan brush lid when classifying the hydrophilic polymer, The problem of clogging of the sieve mesh surface, particles passing through the sieve mesh surface adhere to the inner side wall of the sieving device, and further form large aggregates.The aggregates are peeled off by the vibration of the sieving device and mixed into the product. Can be prevented. By applying ultrasonic vibration to the sieve mesh surface of such a sieving apparatus, the classification efficiency can be further increased.

In the present invention, the temperature of the particulate hydrophilic polymer is 3
0-100 ° C., and the surface of the non-sieving mesh surface other than the sieve mesh which is in contact with the particulate hydrophilic polymer and the sieving device is made of a material having a contact angle to water of 60 ° or more and a heat deformation temperature of 70 ° C. or more. It is mandatory. In other words, the portion of the sieving device that comes into contact with the particulate hydrophilic polymer, particularly the side wall of the sieve mesh surface, is made of a material having specific characteristics, and the temperature of the particulate hydrophilic polymer is adjusted to 30 to 100 ° C. Accordingly, aggregation of the particulate hydrophilic polymer can be suppressed, so that clogging of the sieve mesh surface can be effectively prevented, and a reduction in classification efficiency and classification ability can be prevented. In addition, the particulate hydrophilic polymer that has passed through the sieve mesh surface adheres to the inner side wall of the sieving device, and further forms large aggregates.The aggregates are peeled off by the vibration of the sieving device and mixed into the product. That can be prevented. It is preferable that the material of the present invention is not the sieve mesh but the side wall of the mold that fixes the sieve mesh, and it is particularly preferable that the material of the side wall of the final screen of the classification is that of the present invention.

In the present invention, the particulate hydrophilic polymer is
The temperature is adjusted to 30 to 100 ° C. by heating by a conventionally known method. If the temperature is lower than 30 ° C., the particulate hydrophilic polymers tend to aggregate with each other, which causes a problem in the classification operation. On the other hand, even if the temperature exceeds 100 ° C., the effect of the present invention is not increased, but rather, the temperature of the hydrophilic polymer itself may be deteriorated, or it may be disadvantageous that it is economically disadvantageous. Preferably it is 40-100 degreeC, More preferably, it is 40-90.
° C.

In the present invention, the surface other than the sieve mesh surface, which is in contact with the particulate hydrophilic polymer and the sieving device, is made of a material having a contact angle with water of 60 ° or more and a heat deformation temperature of 70 ° C. or more. is there. If the contact angle of the material of the contact surface to water is less than 60 degrees, the particulate hydrophilic polymer tends to adhere to the inner side wall of the sieving apparatus, which causes inconvenience in the classification operation. In addition, the attached hydrophilic polymer is aggregated, and the vibration of the sieving device causes the aggregate to be peeled off and mixed into the product. Further, if the thermal deformation temperature of the material of the contact surface is less than 70 degrees, it is not possible to withstand the classification operation of the heated and high-temperature particulate hydrophilic polymer, so that the stable classification operation can be continued for a long time. become unable.

Materials satisfying the above characteristics include, for example, synthetic resins such as polyethylene, polypropylene, polyester, polyamide, fluororesin, polyvinyl chloride, epoxy resin, and silicone resin, or glass, graphite, bronze, and the like. Examples include the above-mentioned synthetic resin in which a composite is formed and strengthened with an inorganic filler such as molybdenum disulfide or an organic filler such as polyimide. Among them, polyethylene tetrafluoride, polyethylene trifluorofluoride, polyethylene trifluorochloride, ethylene tetrafluoride-
Fluororesins such as ethylene copolymers, ethylene trifluorochloride-ethylene copolymers, propylene pentafluoride-ethylene tetrafluoride copolymers, perfluoroalkyl vinyl ether-ethylene tetrafluoride copolymers, and polyvinyl fluoride are particularly preferred.

In the present invention, it is more preferable that the sieving apparatus is operated in a heated state and / or a warm state. For example, as a heating means, a jacket which can be heated by electricity or steam is provided, a heating resistor is wound, and a heat insulating material (heat insulating material) is used as a heat insulating means.
The above state can be achieved by winding or the like.

The present invention is effective when applied to a sieving apparatus having a sieve mesh screen having a sieve mesh of 45 μm to 300 μm. As the particle size of the particulate hydrophilic polymer decreases, the sieve mesh surface tends to be easily blocked, and the classification efficiency and the classification ability tend to decrease. In addition, the particulate hydrophilic polymer that has passed through the sieve mesh surface adheres to the inner side wall of the sieving device, further forms large aggregates, and the aggregates are peeled off by the vibration of the sieving device and mixed into the product. Things are easy to happen. Therefore, when the present invention is applied to a sieving apparatus having a sieving screen having a sieve mesh of 45 μm to 300 μm, the effect is remarkable. Further, it is effective to apply the present invention to a sieving device having a sieve mesh surface having a sieve mesh size of 45 to 250 μm.

In a water-absorbent resin whose use has been greatly increased in recent years among the particulate hydrophilic polymers, the fine powder in the water-absorbent resin is an unfavorable component in terms of performance and working environment. Is well known in the art. Therefore, by incorporating the method of the present invention into a process for producing a particulate water-absorbent resin, fine powder can be efficiently removed from a large amount of products, and its utility is extremely large.

The sieving apparatus according to the present invention is provided with a material having the above-mentioned specific properties, and is effective for the above-mentioned method for classifying a particulate hydrophilic polymer. Can also be used preferably for classification. Examples include grains such as wheat flour, agricultural chemicals such as fertilizers, pharmaceuticals, ceramics, cement, inorganic salts such as calcium carbonate, dyes, pigments, resin pellets, and the like.

The contact angle in the present invention was measured by a liquid angle method using a contact angle meter CA-DT-A (manufactured by Kyowa Interface Science Co., Ltd.). The heat distortion temperature is ASTM
It was measured by the method of D-648 (4.6 kg / cm2).

[0022]

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 Acrylic acid, sodium acrylate and trimethylolpropane triacrylate were polymerized in an aqueous solution, and the resulting hydrogel polymer was dried and pulverized to give an average particle diameter of 300.
As a result, a water-absorbent resin powder of μm was obtained.

100 kg of the water-absorbent resin powder at about 40 ° C.
/ H to the sieving apparatus. As the sieving device, a sieving mesh surface having a sieve mesh opening of 850 μm and a
A sieving apparatus (tan brush lid TSM-1600, manufactured by Allgaier) having a mesh screen of μm was used. The lid, sieve mesh frame, and bottom part where the sieving device and the water-absorbent resin powder are in contact with each other are coated with Chukoh Flow adhesive tape AGF-100 (manufactured by Chuko Kasei Kogyo Co., Ltd. 121 ° C)
And an adhesive tape made of glass cloth. There was no trouble during the classifying operation for 8 hours, and a product of the water-absorbent resin powder which passed through the sieve mesh having a sieve mesh of 210 μm was obtained. Almost no adhesion to the sieve mesh side wall and sieve mesh was observed, and the classified product was free of aggregates.

Comparative Example 1 In Example 1, Chukoh Flow adhesive tape AGF-10
The same operation as in Example 1 was performed except that a water-absorbing resin powder at 20 ° C. was supplied using a sieving apparatus not using 0. Adhesion to the sieve mesh side wall and the sieve mesh was observed, and aggregates were mixed in the classified product.

[0026]

According to the present invention, when classifying a particulate hydrophilic polymer, there is no problem that the sieve mesh surface is closed and the classification efficiency and the classification ability are reduced. Further, even when the separation particle diameter is as small as 200 μm or less, the fine particulate hydrophilic polymer that has passed through the sieve mesh surface adheres to the inner wall surface of the sieving device, further forms large aggregates, and the vibration of the sieving device As a result, the aggregates are peeled off, so that there is no problem that particles having a particle size larger than the separation particle size are mixed into the product. Therefore, classification at the separation particle diameter, which has conventionally been difficult to classify stably, can be performed very efficiently, and the classification capability inherent in the sieving apparatus can be sufficiently exhibited.

Claims (3)

[Claims] 1. A method of dry-type particle classification of a particulate hydrophilic polymer using a sieving apparatus, wherein the temperature of the particulate hydrophilic polymer is 30 to 100 ° C. At least a part of the surface where the conductive polymer and the sieving device are in contact, the contact angle with water is 60 degrees or more,
And a material having a heat distortion temperature of 70 ° C. or more. 2. The method according to claim 1, wherein the sieving apparatus has a size of 45 μm to 300 μm.
The method for classifying a particulate hydrophilic polymer according to claim 1, which has a sieve mesh screen having a sieve mesh opening of m. 3. An apparatus for classifying dry particles by sieving, wherein at least a part of a surface other than a sieve mesh surface where the particles come into contact with the sieving apparatus has a contact angle with water of 60 degrees or more and 70% or more. A sieving apparatus characterized by being made of a material having a heat distortion temperature of at least ℃.