JP3166296B2 - Method for removing fine particles adhering to the surface of porous cross-linked copolymer particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing fine particles attached to the surface of porous cross-linked copolymer particles such as a porous ion-exchange resin and a synthetic adsorbent.

[0002]

[0008] Porous crosslinked copolymer particles such as ion exchange resins and synthetic adsorbents are often filled in a column and used by passing through the column. It is often spherical for better operability. However, very small particles of 10% or less of its diameter, which are considered to have been formed during the polymerization, may adhere to the surface, and these fine particles are detached from the crosslinked copolymer particles during use. However, problems such as clogging of a net for supporting the crosslinked copolymer particles placed at the column end, deteriorating liquid permeability, and contamination of the liquid treated in the column by mixing fine particles into the liquid. there were.

[0003]

Means for Solving the Problems The present inventors have been studying a method for removing fine particles adhered to porous crosslinked copolymer particles such as a porous ion exchange resin and a synthetic adsorbent. As a result, a centrifugal force of 10 G to 10000 G is applied to the particles, where G is the gravitational acceleration, and a resistance force substantially equal to the centrifugal force is applied to the particles in contact with the fluid flow, whereby the cross-linking force is increased. The inventors have found that the fine particles adhering to the surface of the coalesced can be separated from the surface and then the crosslinked copolymer can be separated from the released fine particles, thereby completing the present invention.

Hereinafter, the present invention will be described in detail. When fine particles having a size of about several hundredths to several tenths of the diameter are usually attached to the surface of porous crosslinked copolymer particles such as a porous ion exchange resin and a synthetic adsorbent. There are many. Those produced during polymerization of these fine particles have a crosslinked polymer structure similarly to the porous ion exchange resin and the synthetic adsorbent, and thus do not dissolve in organic solvents such as toluene, acetone, and methanol. Further, the adhesion of these fine particles to the porous ion-exchange resin or the synthetic adsorbent is strong, and it is difficult to remove the fine particles with a force given by an ordinary vibrating sieve.

A feature of the present invention is that the gravity acceleration is 1
A porous ion-exchange resin or a synthetic adsorbent in a fluid flow which receives a resistance force of 0 G to 10000 G in a fluid flow received by the ion exchange resin or the synthetic adsorbent, and in a field which receives substantially the same force in a direction opposite to the resistance force. By applying a force greater than the adhesive force between the fine particles and the porous ion exchange resin or the synthetic adsorbent, the fine particles are desorbed, and further, the porous ion exchange resin or the synthetic adsorbent and the fine particles Is to separate them.

[0006] A centrifugal classifier is mentioned as an apparatus for providing the above-mentioned field. A typical centrifugal classifier is a rotating mechanism that applies a centrifugal force of several tens of G to several thousand G to particles, and a fluid flow that applies a force substantially equal to the centrifugal force to the particles in a direction opposite to the centrifugal force. A mechanism for providing an air flow. If the centrifugal force is greater than the force of the air flow, the particles move in the direction of the centrifugal force, and if the centrifugal force is less than the force of the air flow, the particles move in the direction of the air flow to perform classification. .

[0007] The main operating conditions of the centrifugal classifier include a rotation speed for applying a centrifugal force and a supply speed of air for forming an air flow. The balance between these two conditions determines the size of the particles to be classified. In order to efficiently remove fine particles according to the present invention, it is desirable that the air supply speed be high, and that the rotation speed be high accordingly. The centrifugal force acting on a particle is proportional to the cube of the diameter of the particle, and the force acting on the particle due to fluid flow is proportional to the square of the diameter of the particle. Therefore, when particles having a particle size distribution are classified with a constant centrifugal force and air flow, large particles that are more subjected to the centrifugal force are classified toward the circumference of rotation, and small particles that have a small centrifugal force are classified toward the inside. .

The diameter of the particles to be classified, which is determined by the balance between the two conditions, can be arbitrarily determined as long as it is between the diameter of the porous ion exchange resin or the synthetic adsorbent and the diameter of the fine particles. Fine particles can be efficiently desorbed by setting the diameter to about 20% to about 80% of the diameter of the resin or the synthetic adsorbent. Further, in the removal of fine particles according to the present invention, it is desirable to remove the water adhering to the surface of the porous ion exchange resin or the synthetic adsorbent in advance to enhance the fluidity.

The crosslinked copolymer particles to be treated include porous strongly acidic cation exchange resins, weakly acidic cation exchange resins, strongly basic anion exchange resins, weakly basic anion exchange resins, and synthetic adsorbents. And a chelate resin.
The average diameter of the crosslinkable copolymer particles that can be treated is usually 10-2.
The average diameter of the fine particles on the surface is usually 10% or less of the average diameter of the polymer particles, particularly about 0.5 to 10%, and is about 0.1 to 10 microns.

As these crosslinked copolymer particles, those obtained by a known method are used. That is, it is produced as a spherical polymer by subjecting the raw material monomer to suspension polymerization in water using a suitable suspension stabilizer such as gelatin. As a monomer as a raw material, a compound having an ethylenic double bond such as styrene, vinyl toluene, ethyl acrylate, methyl methacrylate, and acrylonitrile is used, and a polyfunctional monomer such as divinylbenzene and ethylene dimethacrylate is used. A crosslinking agent is added, and a crosslinked polymer is obtained using a polymerization initiator such as benzoyl peroxide and azobisisobutylnitrile in the presence of the following porogen.

The porous cross-linked copolymer is mixed with a monomer such as n-heptane, but does not swell the formed polymer, a solvent that swells the formed polymer such as toluene, and a filler such as polystyrene. It is obtained by adding to a monomer mixture alone or in combination and polymerizing. Ordinary porous cross-linked copolymer is 0.1-g / g dry weight.
It has a pore volume of 2.0 ml.

The introduction of a functional group such as an ion exchange group can be carried out by a method known per se. For example, a strongly acidic cation exchange resin can be obtained, for example, by sulfonating an aromatic cross-linked copolymer with concentrated sulfuric acid, chlorosulfonic acid, or the like. The weakly acidic cation exchange resin is obtained by, for example, alkali-hydrolyzing a crosslinked polymer of an acrylate ester.
The strong basic anion exchange resin is obtained by, for example, chloromethylating an aromatic crosslinked polymer and then reacting with an amine.

As an example of the porous strong acid cation exchange resin, there is available Diaion (registered trademark) HPK2 manufactured by Mitsubishi Kasei.
5, RCP160H, Amberlite IR200 manufactured by Rohm and Haas, and the like. Examples of porous weakly acidic cation exchange resins include Diaion W manufactured by Mitsubishi Kasei.
K20, Rohm and Haas Amberlite IRC
50, Bayer's Levatit CNP80, and the like. Examples of porous strongly basic anion exchange resins include:
Diaion HPA25 and HPA75 manufactured by Mitsubishi Kasei, Amberlite IRA904 manufactured by Rohm and Haas, and the like. Examples of porous weakly basic anion exchange resins include Diaion WA21 and WA3 manufactured by Mitsubishi Kasei.
0, Amberlight IRA9 made by Rohm and Haas
3, Dow Chemical 66, etc .;

Examples of the synthetic adsorbent include Diaion HP20 and HP20SS manufactured by Mitsubishi Kasei, Sepabeads (registered trademark) SP850 and SP207, and Amberlite XAD16 manufactured by Rohm and Haas.

[0015]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto without departing from the gist thereof. Example 1 A synthetic adsorbent Diaion (registered trademark) HP20SS having an average particle size of about 100 microns manufactured by Mitsubishi Kasei Co., Ltd. was dried at normal temperature and normal pressure for 72 hours. Using a -15N type precision air classifier, a condition in which the number of revolutions is 3000 rpm and an air supply speed is 2.7 m ³ / minute, that is, a condition in which the particles receive a centrifugal force of about 1000 G and a resistance force almost equivalent to this force from the air flow. Treated with 744.0 grams on the large particle side and 5.4 on the small particle side.
Grams were obtained.

As a result of observing the surface of the synthetic adsorbent contained in the large particles using an optical microscope, it was found that 1 to 5 fine particles per particle adhered to the surface of the untreated synthetic adsorbent. In contrast, no adhered particles were observed after the treatment. Next, the whole amount of the treated large particle-side synthetic adsorbent was wetted with 3.0 liters of methanol, and then packed in a column having an inner diameter of 100 mm and a height of 1000 mm.
One liter of demineralized water was passed at 7.5 liter / min to convert to a wet state with water. The synthetic adsorbent converted into a wet state was treated with a centrifuge having a bucket radius of 100 mm at a rotation speed of 3000 rpm for 5 minutes to remove excess water.

Twenty grams of the wet synthetic adsorbent thus treated together with 80.0 ml of methanol have an inner diameter of 25 g.
mm, placed in a glass tube with a stopper having a height of 200 mm, sufficiently stirred, and allowed to stand for 30 minutes.
Was measured using a quartz cell having an optical path length of 10 mm, and the value was 0.07. The absorbance thus measured can be used as an index of the amount of fine particles contained in the sample, and is hereinafter referred to as Abs 660 nm.

For the untreated synthetic adsorbent, A
When bs660 nm was measured, the value was 0.60. Next, the remaining amount of the synthetic adsorbent remaining in a state of being wetted with water after the above treatment was put in a polyethylene bag, and dropped repeatedly from a height of about 1.5 m toward a concrete floor 50 times. Abs about 20 grams
When measured at 660 nm, the value was 0.08,
The change by the drop test was small. When the fine particles are attached, the fine particles are detached by repeating the drop, but the change of Abs 660 nm was small,
It was confirmed that the amount of the attached fine particles was extremely small.

Example 2 A porous strongly acidic cation exchange resin HP having an average particle size of about 700 microns manufactured by Mitsubishi Kasei Co., Ltd., dried in the same manner as in Example 1.
743.0 grams of K25 was added to Alpine MULTI-
Using a PLEX100MZR type Z classifier, the rotation speed was 92
00 rpm, air volume 45.8 m ³ / min.
The particles were subjected to a centrifugal force of 000 G and a resistance almost equal to this force under the condition that the particles were received from the air flow to obtain 741.0 g of large particles and 1.7 g of small particles.

Observation of the surface of the ion-exchange resin contained on the large particle side with an optical microscope showed that fine particles did not adhere to the surface. Next, Abs 660 nm was measured for 20.0 g of the ion-exchange resin from which excess water was removed after wetting with demineralized water according to the method of Example 1, and the value was 0.06. After performing the same dropping treatment as in Example 1, 20.0 g of Abs6
When measured at 60 nm, the value was 0.08,
The change due to the drop treatment was small.

Abs 660 nm of the untreated ion-exchange resin was measured in the same manner.
Nine. COMPARATIVE EXAMPLE 1 151.0 g of the same dry synthetic adsorbent as in Example 1 was wetted with methanol, and then 55 mm in inner diameter and 90 mm in height.
The mixture was packed in a 0 mm Pyrex column, and then 5.0 liters of methanol was flowed upward through the column at a flow rate of 1.2 liter / hour to remove mixed fine particles. After the completion of the methanol flow, 6.0 L of demineralized water was flowed downward at a flow rate of 1.5 L / hour to bring the synthetic adsorbent into a wet state with water.

Observation of the synthetic adsorbent with an optical microscope revealed that 1 to 3 fine particles adhered per particle on the surface. Further, when Abs 660 nm was measured for 20.0 g of this synthetic adsorbent, the value was 0.09. Next, after dropping 50 times in the same manner as in Example 1, 20.0 grams of Abs6
When measured at 60 nm, the value was 0.33,
An increase due to the drop treatment was observed.

Claims (1)

(57) [Claims] 1. A porous cross-linked copolymer particle to which fine particles have been attached is subjected to a gravity acceleration of G from 10 G to 10,000.
Removing the fine particles adhering to the surface of the crosslinked copolymer particles by applying a centrifugal force of G to the particles and bringing the particles into contact with a fluid flow imparting substantially the same resistance to the particles in a direction substantially opposite to the centrifugal force. Method