JPH03259934A - Spherical porous cellulose particle - Google Patents

Abstract

PURPOSE:To obtain the title particle excellent in mechanical strengths, etc., and useful for a carrier for immobilizing bacteria or enzymes, an ion exchanger or an adsorbing carrier for a perfume, a chemical or the like by selecting a specified spherical porous particle comprising cellulose. CONSTITUTION:The title porous particle which comprises cellulose, forms spheres of a diameter of 0.5mm or above when swollen with water, is composed of a surface having gentle irregularities, having many crazings and pores and being spherical as a whole and an inside composed of voids and partition walls, wherein the sizes and structures of the voids on the central side are different from those of the voids on the surface side, the voids on the surface side are distributed in the radial direction from the inside toward the surface. The voids on the central side consist of a random combination of smaller and larger ones. All of the voids are independent of each other or partially interconnected, the sizes of the voids are such that in a cross section through the center on the side of the shorter diameter of a particle, most of the voids on the surface side have an opening of 30mum or larger, and the voids on the central side have openings of 100mum or larger. The shapes of the voids on the surface and central sides are cylindrical or conical, and has a partially interconnected pore structure as a whole are selected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to porous cellulose spherical particles suitable for immobilization carriers for bacterial cells and enzymes, ion exchangers, adsorption carriers for perfumes, drugs, etc.

[Conventional technology]

Cellulose particles are widely used in many fields as immobilized carriers for bacterial cells and enzymes, adsorbent carriers for fragrances and drugs, cosmetic additives, and as various ion exchangers by introducing various functional groups. It has become. For these applications, whether used in packed beds or stirred tanks,
A spherical shape with excellent fluidity and mechanical strength is advantageous. Furthermore, the amount of bacteria, enzymes, and drugs that can be immobilized and adsorbed and the number of functional groups that can be introduced are proportional to the surface and internal surface areas of the particles. Therefore, it is advantageous to make the particles porous. Many patent applications have been filed to date regarding cellulose spherical particles and porous spherical particles. For example, Tokukai Showa 4s
45-6o75 discloses a method for obtaining porous cellulose particles of 16 to 170 mesh by discharging viscose in the form of droplets and coagulating and regenerating it.

In Japanese Patent Publication No. 57-7162, the apparent density is 0.4 g.
A hollow cellulose fine granule having a size of 16 to 170 meshes and a large void approximately in the center is disclosed.

Japanese Patent Publication No. 57-45254 discloses that by heating and solidifying a viscose suspension in chlorobenzene while stirring continuously, particles having a particle size of 150 to 350 μm account for 85% by volume can be obtained. ing.

Japanese Patent Publication No. 55-39565 discloses that a solution of cellulose triacetate in an organic solvent is dropped into an aqueous medium containing a dispersant such as gelatin while stirring, and is solidified by heating to form spherical particles of cellulose triacetate. A method for producing cellulose spherical particles by saponifying cellulose is disclosed. The particle size of the particles obtained by this method is 30 to 500 μm.

JP-A No. 63-90501 discloses that a mixture of viscose and a water-soluble polymer compound is mixed with an anionic water-soluble polymer compound to produce a fine particle dispersion, which is coagulated by heating or a coagulant and regenerated by an acid. A method is disclosed. In this method, water-soluble polymers are removed during the steps of coagulation, regeneration, and water washing, and the average particle size is 300 am or less and the pore size is 0.02.
The purpose is to obtain porous microcellulose particles having a maximum value of pore volume in an interval of ~0.8 μm and a total pore volume of 0.025 dl/g or more in the same interval.

However, all of these conventional particles have a small diameter (500μ).
It has a structure in which a large number of fine holes (5 μm or less) are placed in the hole (5 μm or less).

However, such small particles having only minute pores cannot be said to be excellent when applied to the above-mentioned uses.

To this end, cellulose particles of this type with as large a diameter as possible and with wide pores have recently been developed, and several patents have been filed for this, for example, in JP-A-6
No. 4-43530 discloses that droplets of cellulose solution are cooled and frozen below the solidification temperature, and then the solvent is removed.
A method for producing cellulose porous particles having a large number of pores of 2 μm or more and a continuous pore structure communicating with each other is disclosed.

JP-A-60-155245 discloses a method for producing porous spherical particles of cellulose acetate having a diameter of 0.05 am+ to 10 mm, which become porous cellulose particles when saponified.

Furthermore, cellulose sponge is known as a large-diameter cellulose structure. The pore diameter is several hundred μm or more, and cellulose porous materials are also known that have a continuous pore structure of large-diameter pores (several hundred μm or more) made by slicing this cellulose sponge into cubic shapes.

[Problem to be solved by the invention]

The problem to be solved by the present invention is this type of cellulose porous particles, which have many large pores without having a large diameter, and furthermore, these pores are connected, and the particles themselves have considerable mechanical strength. It means developing something new.

Originally, when cellulose porous particles are used for applications such as carriers and ion exchangers, the larger the surface area within the particles, the greater the amount of immobilized unit carrier amount and the ion exchange capacity.
The particles become so-called particles with good performance.

However, an increase in the internal surface area means an increase in the number of small-diameter pores and a decrease in the number of partition walls, which leads to a corresponding decrease in strength and unavoidable weight loss during stirring operations.

In addition, when the number of small-diameter pores increases, the pore structure changes during drying, and when it is swollen with water or chemicals again, it does not return to its original pore structure.
The amount of water retained and the amount of chemicals retained decrease, resulting in a decrease in so-called reactivity.

Therefore, large-diameter cellulose spherical particles with a relatively large internal surface area, strength, and good restorability are extremely preferable.

The present invention is to develop such cellulose particles.

[Means for Solving the Problem] This problem is solved by providing the following cellulose particles. That is, (A) it is made from cellulose, and (B) it exhibits a spherical shape with a diameter of 0.5 mm or more when swollen with water, has a gentle unevenness on its surface, has many cracks or small pores, and exhibits an overall spherical shape. , (C) <4) The interior is protected from pores and partition walls, and (
El) The size and structure of the pores are different between the center side and the surface side, (c) On the surface side, there are many pores radially extending from the inside toward the surface, (=) On the center side, there are many pores. The pores are randomly mixed in size and small, and (n) all the pores are independent or partially communicated through the partition wall.
(f) Regarding the size of the pores, in the cross section of the approximately central part of the short axis side of the particle, most of the pores on the surface side are occupied by pores of 30 μm or more, and on the center side, the size of the pores is 100 μm. (g) The pores are columnar to conical in shape, and (D) Cellulose pores are porous with a partially continuous pore structure as a whole. quality spherical particles.

[Function and structure of the invention]

The particles of the present invention basically satisfy the requirements (A) to (D) above. Each item will be explained below with reference to the drawings.

First, the particles of the present invention are made from cellulose.

Cellulose is conventionally known, and includes all conventionally known celluloses, and in some cases, regenerated cellulose is also included.

The particles of the present invention have a spherical appearance with a diameter of 0.5M or more when swollen with water. However, spherical shape is a broad concept that includes not only true spherical shape but also elliptical shape and granular shape. The surface may or may not have a coating, and the average thickness of the coating is 10 am or less, preferably 5 μm or less. Even if a film is formed, this film is porous with small pores and cracks present. Whether a film is formed or not, the surface is gently uneven and has many small pores and cracks.

The internal structure basically consists of holes and partition walls, and the size and structure of the holes are different between the center side and the surface side of the sphere. On the surface side, the pores extend radially from the inside toward the surface and reach the surface, and most of the pores in this region have a diameter of 30μ in the cross section of the approximately central part of the short diameter side of the particle.
m or more and 150 μm or less, preferably 60 μm to 100 μm
It is about m. The center part of the center means the range of ±10%, preferably ±5% from the center. The thickness of the partition wall of the pore structure on the surface side is not constant, but is usually 3 to 30 μm, preferably 5 to 10 μm.
The thickness is about m.

On the center side, pores are randomly mixed in size, and most of the pores in this area have a diameter of 1 in the cross section of the center section.
00 to 300 μm, preferably 100 to 200 μm. Although the thickness of the partition wall on the center side is not constant, it is usually 10 μm or more.

The pores on both the center side and the surface side communicate with a portion of adjacent pores through small holes or cracks penetrating the partition wall, and the shape of the pores is usually cylindrical or conical.

Since the particles of the present invention have the above-described structure, they are porous as a whole.

The physical properties of the particles of the present invention include mechanical strength of 8 to 30%.
It is. However, this mechanical strength is determined by stirring the particles under certain conditions to apply shearing force, and then calculating the part separated from the particles by shearing from the weight before and after stirring, which is used as an index of mechanical strength. That is, 2 g of the freeze-dried grains were placed in an IF beaker, and 500 g of 2 N -NaOH was added thereto. 50 Or, p, m using a stirrer with a 7 cm rotating blade.
Stir for 2 hours at a rotation speed of . The temperature of the system is maintained at 25°C. After stirring, the mixture is filtered through a 40-mesh stainless steel filter, washed with a large amount of water, dried with hot air, and weighed.

As is clear from this, particles with a large weight loss have a low strength, and particles with a small weight loss have a high strength. As for other physical properties, for example, water retention amount varies depending on particle size and pore structure, but water retention is 5 g to 1 g per 1 g of particles.
It is 5g.

The particles of the present invention have the above-mentioned basic structure and are especially large in diameter, so they have excellent fluidity and workability. In addition, due to the continuous pore structure with large diameter pores, mass transfer is rapid, and bacteria immobilization, adsorbent immobilization, and ion exchange reactions are fast and efficient. In addition, due to the large-diameter pore structure, the fine structure changes during drying, and when re-swelled, the amount of water retained, the amount of chemicals retained, and the amount of ion exchange are significantly reduced, which is a significant improvement.

In addition, although it has a large number of pores inside, the amount of ion exchange and immobilization is generally slightly lower than that of conventional cellulose porous particles, which have many small pores. , strength is improved and weight loss due to stirring during reaction and culture is reduced. The amount of bacteria immobilized is largely influenced by factors other than the surface area, and in many cases, the structure of the present invention with a reduced internal surface area has a larger amount of immobilized cells and stronger adhesion strength than cellulose particles with a larger internal surface area. Yes.

As mentioned above, the cellulose porous spherical particles of the present invention have the conditions to enable industrial large-scale use as immobilization carriers and ion exchangers, and because they are cellulose, they are stable against chemicals. It also has the property of being non-toxic, so it can be used in a wide range of industrial fields such as pharmaceuticals and food.

Although the method for producing the cellulose porous particles of the present invention is not limited in any way, a preferred production method will be described below.

This manufacturing method basically involves mixing viscose and calcium carbonate, pressing the mixture and extruding it into droplets through a nozzle.
In this method, the cellulose is dropped onto a coagulation/regeneration bath, and the cellulose is coagulated and regenerated in the form of droplets, and the calcium carbonate is decomposed with acid at the same time. Desulfurization, bleaching, washing, and drying are then carried out as necessary.

In this method, first, viscose and calcium carbonate are mixed to create a viscose liquid containing calcium carbonate. The solution is pressurized and extruded into droplets through a nozzle,
The droplets are allowed to fall onto a coagulation/regeneration bath. This method produces cellulose porous particles having an internal pore structure corresponding to each viscose condition, coagulation/regeneration condition, etc. by stirring the mixture for a predetermined period of time.

For example, the viscose used has the following properties. Cellulose concentration is 3 to 15% by weight (hereinafter expressed as wt%),
Preferably it is 4 wt% to 10 wt%. The ammonium chloride value is 3 to 2, preferably 4 to 9. Alkali concentration is 2-15-t% as caustic soda, preferably 5-1
It is 3wt%.

The viscosity of viscose is 50 centipoise at 20°C.
io, ooo centipoise preferably 100 centipoise to 7,000 centipoise.

At this time, if the cellulose concentration, ammonium chloride value, and alkali concentration are outside the above-mentioned predetermined ranges, the following undesirable causes will occur. That is, if the cellulose concentration is low, the mechanical strength of the particles produced will be low, and if it is high, the viscosity of the liquid will increase and the discharge from the nozzle will not be uniform, resulting in irregular particles. If the ammonium chloride value is high, the shape of the particles produced will be distorted and inconsistent. If it is low, the mechanical strength of the particle surface will be weak and the surface will break during stirring and become small. Also, if the alkali concentration is high, the particle shape tends to become distorted, and if the alkali concentration is low, the surface tends to break during stirring.

There are no particular restrictions on the calcium carbonate used, and either light calcium carbonate or heavy calcium carbonate may be used. Generally, from the viewpoint of workability such as ease of mixing and prevention of nozzle clogging, particles having an average particle size of 1 μm to 15 μm are used. The internal pore structure of the cellulose porous particles is not greatly affected by this average particle size of calcium carbonate. Calcium carbonate per 1 part by weight of cellulose in viscose #)
0.1 to IO parts by weight, preferably 0.4 to 7 parts by weight, are used.

The amount of calcium carbonate does not change the basic internal pore structure of the particles, but it is involved in the generation of pores, especially fine pores of 30 μm or less, and there is a relationship that as the amount of calcium carbonate increases, the number of pores also increases. .

Viscose and calcium carbonate are mixed by stirring with a stirrer or kneader, and the calcium carbonate powder can be added directly to the viscose during stirring, or the calcium carbonate powder can be dispersed in water in advance and then dispersed. You can also add liquid.

Any method of pressurization may be used as long as the discharge pressure from the nozzle does not easily fluctuate, but pressurization using a gear pump and pressurization using air pressure are industrially advantageous. The pressure at the time of pressurization may be a pressure that allows the liquid mixture to be discharged from the nozzle.

The nozzle only needs to have a diameter of 0.1 mm or more, and there are no particular restrictions on the material or shape. If the diameter is smaller than 0.1m+, the nozzle will be easily clogged and productivity will be poor;
Small particles, such as those produced with nozzles smaller than m, are not the object of this invention.

Inorganic acids such as hydrochloric acid, phosphoric acid, carbonic acid, and sulfuric acid are used as the coagulating/regenerating agent for coagulating/regenerating cellulose and acid decomposing calcium carbonate, which is a foaming agent, but hydrochloric acid is preferred. Not only is it advantageous from the viewpoint of productivity to install multiple coagulation/regeneration baths instead of one and use them in series or in parallel, but if the conditions of each coagulation/regeneration bath are varied, It is also advantageous in that it is possible to produce particles with an internal pore structure different from those produced in individual baths. The concentration of acid in the coagulation/regeneration bath is usually Log/1 to 90 g/l in the case of hydrochloric acid.
More preferably, the concentration of salt in the bath is 15 g/l to 70 g/l, in the case of calcium chloride and sodium chloride, and the sum of the two is O to 400 g/l, more preferably 100 to 2
00g/jl! It is. The coagulation/regeneration bath temperature is usually 10-5
0°C, more preferably 20-40''C.

According to the production method of the present invention, cellulose porous particles with various internal pore structures can be produced by adjusting the ammonium chloride value of viscose, the concentration of acid in the coagulation and regeneration bath, the temperature of the bath, and the concentration of salt. Can be created. As mentioned above, in the production method of the present invention, the ammonium chloride value of viscose is usually 3 to 1.
2. The concentration of acid in the coagulation/regeneration bath is 10g/in the case of hydrochloric acid.
Cellulose porous particles are created under conditions of 1 to 90 g/f, bath temperature of 10 to 50°C, salt concentration in the bath of calcium chloride and sodium chloride, and a total of 0 to 400 g/l. . At this time, if cellulose particles are created under conditions where the coagulation/regeneration reaction of cellulose proceeds quickly, that is, viscose with a low ammonium chloride value (so-called ripening), high acid concentration, low salt concentration, and bath temperature. When a high coagulation/regeneration bath is used in combination, the cellulose porous particles created have different structures between the center and the surface of the sphere, with many small-diameter pores extending radially from the inside to the surface on the surface. It has a structure in which holes of relatively large diameter are randomly mixed in size on the center side.

In this case, the production conditions are usually viscose with an ammonium chloride value of 4 to 6.5, and a coagulation/regeneration bath acid concentration of 50 with hydrochloric acid.
~80g/1, salt concentration is O~200g# in total of sodium chloride and calcium chloride! It is. Scanning electron micrographs of cellulose porous particles having this type of internal pore structure are shown in FIGS. 1 and 2. Figure 1 is a surface photograph, and Figures 2 and 3 are central cross-sectional photographs.

[Example] The present invention will be explained in detail with reference to Examples below.

Example 1 400 g of viscose with a cellulose concentration of 9.0%, a viscosity of 4,500 centipoise, an ammonium chloride value of 8.5, and an alkali concentration of 6.1% and calcium carbonate (Nitto Funka Kogyo SS"30 average particle size 7) .4.czm) 37g
into a 12-beaker and stirred at 700 r, p, m with a stirrer.
, for 20 minutes to create a viscose liquid containing calcium carbonate. After that, the viscose liquid was sucked from the beaker using a tube pump (Tokyo Rika Kikai Microtube Pump MP-3), pressurized, and pumped at a rate of 5 cc/min through the outlet equipped with five syringe needles with a diameter of 1.2 mm. It was extruded into droplets and dropped onto a 5E beaker which was used as a coagulation/regeneration bath. The concentration of hydrochloric acid in the coagulation/regeneration bath is 25g/
f, temperature was 25°C, salt concentration was 250 g/l in total of sodium chloride and calcium chloride. It took about 1 hour from the time when the droplets started dropping into the 51 beaker, which is a coagulation/regeneration bath, to the end of dropping, and then the cellulose was coagulated and regenerated, and the calcium carbonate was acid-decomposed for 2 hours. Continuously stir the solidification/regeneration temperature to uniformly solidify, regenerate, and
Care was taken to ensure that acid digestion occurred.

It was then washed with a large excess of water and treated with 2g/l of caustic soda and 2g/l of caustic soda.
Desulfurization was carried out at 70°C for 1 hour in a desulfurization tower containing g/l of sodium sulfide. Then wash with a large excess of water, then 2
．． 2 in a bleach bath containing 6 gel of sodium hypochlorite
Bleaching was carried out for 0°C12O minutes and washing was performed again with a large excess of water to obtain cellulose porous particles. The shape of the obtained particles was spherical particles with an average particle diameter of 3.4 mm in a water-swollen state.

Scanning electron micrographs of the obtained particles are shown in FIGS. 1, 2, and 3.

FIG. 1 shows the front surface, and FIGS. 2 and 3 show cross sections of the central part.

[Brief explanation of drawings]

Figures 1 to 3 all show scanning electron micrographs of porous cellulose particles. (The above) ≦2i1 Cf'dietnuku1 1nu1 nifro: 3 The official procedure order (method) % formula % 2. Name of the invention Cellulose porous spherical particles 3. Make an amendment. Relationship with patent case Address of patent applicant
96-11 Asahi, Kanazu-cho, Sakai-gun, Fukui Name Fukui Chemical Industry Co., Ltd. Representative Takeuchi Part 4, Agent 〒530 256゜7゜8゜1-1, Minamimori-cho, Kita-ku, Osaka City Details subject to amendment Column for brief explanation of cattle drawings Contents of amendments List of attached documents as attached This is a scanning electron micrograph of porous cellulose particles.'' has been corrected as follows. “Showing the particle structure of cellulose porous particles.” (End)

Claims (1)

[Claims] (1) (A) Made of cellulose; (B) When swollen with water, it exhibits a spherical shape with a diameter of 0.5 mm or more, with a gently uneven surface and many cracks and small pores, giving it an overall spherical shape. (C) (A) The interior consists of pores and partition walls, (B) The size and structure of the pores are different on the center side and the surface side, (C) The pores on the surface side are smaller than the inside. (d) On the center side, pores are randomly mixed and sized, and (e) All pores are either independent or partially connected through partition walls. (f) The size of the pores is such that in the cross section of the approximately central part of the minor axis side of the particle, most of the openings on the surface side are pores of 30 μm or more;
The pores on the center side are 100 μm or more; (G) The pores are cylindrical or conical in shape on both the surface side and the center; (D) The pores are porous with a partially continuous pore structure as a whole. Cellulose porous spherical particles characterized by: