JPH0411635A - Porous polyacrylonitrile bead - Google Patents

Abstract

PURPOSE:To obtain a porous bead which can desirably be used as a carrier for filtering water for transporting living fishes or water in a tank for keeping fishes by using an acrylonitrile polymer and specifying the particle diameter and the porosity. CONSTITUTION:Porous polyacrylonitrile bead comprising an acrylonitrile polymer and having a particle diameter of 1-20mm and a porosity of 20% or above. Because it has water retentivity, adsorptivity and good separation efficiency as well as a large porosity, chemical stability and easy handleability, it can be desirably used as a carrier for filtering water for transporting living fishes, etc., and water in a tank for keeping fishes, a decorative material or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to porous beads suitable for use as carriers for transporting live fish, etc., for filtering habitat tank water, as decorative materials, and the like.

(Conventional technology) Traditionally, sawdust has been used to transport live fish (including crustaceans such as shrimp and crabs, fish such as sea bream and flounder, and various shellfish), as well as for cultivation, ornamentation, transportation, and other methods. Activated carbon formed in layers is used for acclimation and purification of habitat tank water for other purposes.
Corals, ostracods, and various fibers have been used.

(Problems to be Solved by the Invention) The sawdust used in the above-mentioned method itself undergoes putrefaction and decomposition, and the elution of the decomposition products into water has a negative effect on the survival of live fish, etc., and it is possible to recycle it based on the same reasoning. It cannot be used or used for a long period of time, and due to recent environmental destruction problems, it is difficult to obtain and the price has soared.Furthermore, due to its form, it can only be used for extremely limited types of live fish such as shrimp and crabs. There was a problem that it could not be applied.

In addition, we try to keep live fish etc. alive for various purposes.
Activated carbon, coral powder, shells, etc. are excellent for purifying habitat tank water, but they are expensive, require special equipment and tank water circulation equipment, and are not easy to regenerate when deactivated. Furthermore, there were many problems such as the need for maintenance and management.

The inventors of the present invention have conducted further intensive studies based on the problems of the conventional techniques described above, and have arrived at the present invention.

That is, an object of the present invention is to provide industrially advantageous porous beads suitable for transporting live fish, carriers for filtration of habitat tank water, decorative materials, etc. The purpose of this invention is to provide porous beads that have the function of adsorbing waste products excreted by living organisms and supplying oxygen to water, and that can allow live fish and the like to survive for a long period of time.

(Means for Solving the Problems) The object of the present invention described above is to obtain acrylonitrile (hereinafter referred to as A
(abbreviated as N) system polymer with a particle size of 1 to 20j
This is achieved by using porous polyacrylonitrile (hereinafter abbreviated as PAN) thread beads having a porosity of 11Jf and a porosity of 20% or more. The present invention will be explained in detail below.

The AN-based polymer used in the present invention may be any polymer containing AN as a main component, ranging from a homopolymer containing 100% AN to a polymer containing other polymers that can be copolymerized with AN. It may be a copolymer. The comonomer to be copolymerized is not limited and is appropriately selected depending on the purpose to be imparted to the porous PAN beads. There is no lower limit to the AN component in the copolymer, but if you are strict about it, porous PAN
From the viewpoint of system bead formation technology and performance, the content is preferably 80% or more.

The particle size of the beads made of the AN-based polymer is 1 to 20jf.
Beads with a particle diameter of 201 nI or more do not exhibit the effectiveness of the present invention, and beads with a particle diameter of 1 lfll or less are particularly difficult to handle and are not preferred. More preferably, particles having a particle size of 1 to 15 jff are suitably used.

The beads made of the AN-based polymer have a particle size of 1 to 20 f.
It is necessary that the thickness is f and the porosity is 20 or more. The porosity here is measured by a conventional mercury intrusion method, and if the porosity is less than 20%, the inner surface area of the pores is small per unit weight or unit volume of the beads. The effect of prolonging survival will be smaller.

Beads made of the AN-based polymer may contain inorganic powder as long as substances that endanger the survival of live fish etc. do not elute, and there are no particular restrictions on the inorganic powder. Carbonates, sulfates, phosphates, etc. and double salts such as calcium and barium, naturally occurring rock powders, ore powders, natural calcium compounds such as shells and corals, their fired products, and even Activity etc. can also be exemplified. Particle diameter/'i of the inorganic powder is not particularly limited, but from the viewpoint of the formability of porous PAN beads containing the inorganic powder, etc.
00 microfron or more is preferable.

Porous according to the present invention! As a method for producing PAN-based beads, known methods are employed, and examples include the following.

The AN-based polymer polymerized by a conventional method is dissolved in an appropriate solvent to obtain a polymer R solution, and the solution is divided into particles to obtain a precipitant for the AN-based polymer (the polymerized and coagulated particulates). AN
A system polymer is obtained, and then the solvent is removed (water is used) and an appropriate heat treatment is performed to form micropores communicating with the particle surface to obtain porous beads. Alternatively, the polymer solution may be sprayed in the form of particles, and the solvent may be removed and the continuous pores formed all at once by operations such as depressurization and heating.

Furthermore, the polymer powder can also be granulated using a suitable device such as a Henschel mixer.

It is easy to incorporate the inorganic powder at the same time as the above-described process of dissolving the AN-based polymer in a solvent, or in a process before or after the process. Furthermore, in order to assist in the formation of continuous pores, 8f microbubbles may be introduced into the polymer solution, or a blowing agent that generates gas due to some stimulus (heat, pH, etc.) may be added and blended.

The thus obtained porous PAN-based beads according to the present invention have excellent selective affinity with digestive bacteria such as ammonia, are chemically stable, and have a low air content resulting from the open pores. Due to its properties such as high volume, high water retention capacity, and moderate specific gravity, it is especially suitable for use in the fields of water retention materials for transporting live fish, etc., and filtration materials for purifying habitat tank water. used. It can also be widely used in fields such as carriers and design materials.

(Function) Although the reason why the porous PAN beads according to the present invention exhibits various excellent performances has not yet been fully elucidated, it is generally thought to be as follows.

That is, the PAN-based material, which is probably due to its nitrile group properties, has a selective affinity with ammonia-digesting bacteria, etc., and therefore, when the beads of the present invention are applied in water, they have a continuous porous structure. Ammonia-digesting bacteria present in water are adsorbed on the vast inner and outer surfaces of the beads due to their high porosity. Live fish and the like discharge various waste products into water as a result of their biological maintenance. When the concentration of ammonia in waste products becomes high, it will cause the death of live fish, etc. However, the digestive bacteria adsorbed to the beads of the present invention decompose it and eventually release it outside the system as nitrogen, so the concentration of ammonia in water will decrease. This suppresses the rise in the number of fish and prolongs the survival of live fish.

As the beads of the present invention have a high porosity as described above, when applied, the air held in the pores and brought into the water, that is, the oxygen content, gradually dissolves into the water and is consumed by live fish etc. The effect of replenishing dissolved oxygen also prolongs the survival of live fish.

Furthermore, the beads of the present invention containing an inorganic powder easily settle when applied in water with a large specific gravity due to the inorganic powder, and in addition to exhibiting the above-mentioned effects without wasting the inorganic powder. Powder components such as calcium and barium have the effect of neutralizing acid components such as uric acid and nitric acid in the excreta of live fish, etc., delaying changes in fluid properties and prolonging the survival of live fish, etc.

It is presumed that this is because the oxidation state of each constituent component formed by the oxidation reaction during firing becomes a highly reactive state, even though the inclusion of the fired inorganic powder is even more effective. Activated carbon embodies these elements.

(Examples) The present invention will be described in more detail with reference to Examples below, but the scope of the present invention is not limited by the description of these Examples.

Reference example AN/Methyl acrylate) = 90/10 (weight ratio: 1 k (MW))
10.000 PAN thread polymers were obtained. washing, dehydration,
After drying, the polymer was crushed into powder with an average particle size of 80
0 micron shell powder (20% by weight based on Bolimani)
Dimethylformamide was mixed and stirred with heating to obtain an AN polymer solution having a polymer concentration of 10% by weight. The solution was dropped into room temperature water through a space 7α through a nozzle with a hole diameter of 3IInII without performing defoaming. The solidified particulate AN-based polymer was washed with running water to remove the solvent, then put into boiling water, maintained for 2 hours, cooled, and recovered. It was then dried in a hot air dryer maintained at 50'C for 10 hours. The porous PAN beads (sample A) thus obtained had an average particle diameter of 4.5B, a porosity of 62% when measured by mercury porosimetry, and a fine particle cross section when observed with a scanning electron microscope. It was observed that there were countless pores that were connected to the particle surface. Sample B was obtained in the same manner as Sample A except that the AN polymer solution was 50'C and the nozzle pore diameter was 1III. Sample B has an average particle diameter [, 8H1 porosity 7
It was 8%.

Example【.

5 parts of porous PAN-based bead sample B of the reference example, water-dispersible acrylic resin (Nippon Shokubai Chemical Co., Ltd., Acryset) EX
-14) 40 parts, surfactant (Emulgen 90 manufactured by Kao ■)
9) After thoroughly mixing and dispersing 10 parts of gEJ butyl cellosolve for paint and 85 parts of deionized water, paint it on an aluminum plate using a brush, and heat it at 120'C in an electric furnace.
X A painted board was obtained by baking for 10 minutes.

The painted surface of the board had strong adhesion of beads, and its unevenness gave subtle shading, presenting an innovative design and satisfying aesthetic sense.

Example 2 Styrofoam lidded container of the same size (lid with a transparent lid,
A2. Yaita, you can observe 1 part power and 1 part power) and put 10 shrimp each that had been cultured in the same tank into each container.

Sawdust was placed in one container, and porous PAN-based beads Sample A, which was a reference example containing 140% water by weight (compared to dry scorched beads), was placed in the other container until the vibration of the shrimp was no longer recognized in the shrimp body height container. The average elapsed time was measured.

Table 1 shows the results.

As shown in Table 1, it can be seen that when the porous WPAN beads of the present invention are used, they have an extremely superior effect of prolonging the survival time of live fish, etc., compared to conventional sawdust.

Example 3 Two identical live fish habitat tanks (capacity: 150 It) filled with artificial seawater were prepared, and five 3-year-old cultured sea bream fish from the same lot were simultaneously released into each tank. Then, shells equivalent to 1 volume of tank water were gently added to one container, and the porous PAN-based bead sample RA of the reference example was gently added to the other container.

The average elapsed time until the sea bream in the tank turned upside down or turned its body horizontally was measured, and the results shown in Table 2 were obtained.

Table 2 As shown in Table 2, it is understood that the porous beads of the present invention have excellent adsorption and filtration performance even when added to water, thereby exerting the effect of extending the survival time of live fish, etc. Ru.

(Effects of the Invention) The porous PAN beads of the present invention are particles formed porous with micropores connected to the particle surface, have a large porosity, are chemically stable, and are easy to handle. In addition, it has water retention, adsorption, and separation abilities, so it can be used as a carrier for bioreactors, materials for chemical modification, fillers and extenders in various fields, and as an addition to paints. It can be used in a wide range of applications, such as decorative materials that impart properties, adsorbents, water retention materials, filtration materials, and cushioning materials.

Particularly, a noteworthy effect of the present invention is that particles having high water retention properties brought about by their hydrophilicity, special selective adsorption properties, filtration, purification functions, etc. are provided.

Claims (1)

[Scope of Claims] 1. Made of an acrylonitrile polymer, with a particle size of 1 to 1.
Porous polyacrylonitrile beads having a diameter of 20 mm and a porosity of 20% or more. 2. The porous polyacrylonitrile beads according to claim 1, which contain an inorganic powder. 3. A water retaining material for transporting live fish, comprising the porous polyacrylonitrile beads according to claim 1. 4. A filtering material comprising the porous polyacrylonitrile beads according to claim 1.