JP2769485B2 - Cellulose porous spherical particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to porous cellulose spherical particles suitable as a carrier for immobilizing bacteria and enzymes, a carrier for adsorption of ion exchangers, fragrances, chemicals and the like.

[Conventional technology]

Cellulose particles are widely used in many fields as a carrier for immobilizing bacteria and enzymes, as a carrier for adsorption of fragrances and chemicals, as a cosmetic additive, and as various ion exchangers by introducing various functional groups. It has become. In these applications, a spherical shape having excellent fluidity and mechanical strength is advantageous even when used in any method such as a packed bed and a stirring tank. In general, the amount of cells, enzymes and drugs to be fixed and adsorbed and the number of functional groups that can be introduced are proportional to the surface area of the particles and the internal surface area. Therefore, it is advantageous to make the particles porous. Numerous patent applications have been filed for cellulose spherical particles and porous spherical particles. For example, JP-A-48-60753 discloses a method in which viscose is discharged in the form of droplets and solidified and regenerated to obtain porous cellulose particles of 16 to 170 mesh.

Japanese Patent Publication No. 57-7162 discloses that the apparent density is 0.4 g / cm ³ or less.
There is disclosed a hollow cellulose fine particle having a large void substantially at the center of 16 to 170 mesh.

JP-B-57-45254 discloses that a viscose suspension is heated and solidified in chlorobenzene with continuous stirring to obtain particles having a particle size of 150 to 350 μm and occupying 85% by volume. ing.

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

JP-A-63-90501 discloses that a mixture of viscose and a water-soluble polymer compound is mixed with an anionic water-soluble polymer compound to form a fine particle dispersion, which is coagulated with a heating or coagulant and regenerated with an acid. There is disclosed a method for causing this to occur. In this method, the water-soluble polymer is removed in the steps of coagulation, regeneration, and washing with water, the average particle diameter is 300 μm or less, and the pore diameter is 0.02 to 0.8 μm. It is intended to obtain porous microcellulose particles having a total pore volume of 0.025 ml / g or more.

However, these conventional particles are all small particles (500μ
m or less) and a large number of fine holes (5 μm or less).

However, it is hard to say that a material having such a small particle size and having only micropores is excellent in application to the above-mentioned applications.

For this purpose, recently, cellulose particles of this kind having a diameter as large as possible and having large pores have been developed, and several patents have been filed with respect to such cellulose particles.
In Japanese Patent No. 64-43530, a droplet of a cellulose solution is 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 m or more and having a continuous pore structure communicating with each other is disclosed.

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

Also, a cellulose sponge is known as a large-diameter cellulose structure. The pore size is several hundred μm or more, and a cellulose porous body having a continuous pore structure of large-diameter pores (several hundred μm or more) formed by slicing this cellulose sponge and forming a cubic shape is also known.

[Problems to be Solved by the Invention] The problem to be solved by the present invention is this kind of cellulose porous particles, having a large number of large and large pores, and these pores communicate with each other. The purpose is to develop a new particle having considerable mechanical strength.

Originally, when cellulose porous particles are used for applications such as carriers and ion exchangers, the larger the surface area within the particles, the larger the amount of immobilization per unit carrier amount and ion exchange capacity, and so-called particles with good performance Becomes However, an increase in the internal surface area means an increase in small-diameter holes, and a decrease in the number of partition walls. The strength is correspondingly reduced, and it is inevitable that the weight is reduced during a stirring operation.

Also, when the number of small holes increases, the pore structure changes during drying,
When swelled again with water or chemicals, the water does not return to the original pore structure, but the water retention and the amount of chemicals decrease, so-called reactivity decreases. Accordingly, large-diameter cellulose spherical particles having a large internal surface area to some extent, and having good strength and good resilience 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 composed of cellulose, and (B) it has a spherical shape with a diameter of 0.5 mm or more when swollen with water,
(C) The interior is composed of pores and partition walls, and a large number of holes are randomly mixed in large and small sizes to form a spherical shape. And one of the holes has a diameter of about 15 at a substantially central section on the short diameter side of the hole.
0 μm or more, it has a substantially circular or polygonal shape, and the holes communicate with some or all of the adjacent holes by small holes or cracks penetrating the partition walls. (D) Partially continuous holes as a whole These are particles that are structured and porous.

[Function and Configuration of the Invention]

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

First, the particles of the present invention are made of cellulose. Cellulose is conventionally known, and any of those conventionally known as cellulose is included, and in some cases, regenerated cellulose is also included.

The particles of the present invention have a spherical shape with a diameter of 0.5 mm or more when swollen with water. However, the spherical shape is a broad concept including not only a true spherical shape but also an elliptical shape and a granular shape. The surface may or may not have a coating, and the thickness of the coating is on average 10 μm or less, preferably 5 μm or less. Even when a coating is formed, the coating is porous with small holes and cracks. Regardless of whether the film is formed or not, the surface has gentle irregularities and many small holes and cracks are present.

The basic structure of the internal structure is composed of pores and partition walls, and these pores are randomly present in large and small sizes.
One size of the hole is 150 μm or more, and preferably about 200 μm, in a cross section of the center near the minor diameter side of the hole. Substantially the center means a range of ± 10%, preferably ± 5% from the center. The thickness of the partition walls is not constant, but usually 20 to
It has a thickness of 500 μm, preferably about 40 to 100 μm, and occupies 3 to 30%, preferably about 20% of the volume of the whole particles.

The holes communicate with some of the adjacent holes by small holes or cracks penetrating the partition. The number of holes is preferably 2 or more, more preferably 30 or less, and particularly preferably 4 to 20 in the cross section at the center. The shape of the hole itself is usually cylindrical or conical.

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

The physical properties of the particles of the present invention are 5 to 15%.
It is. However, the mechanical strength is obtained by agitating the particles under a certain condition to give a shearing force, and determining the portion separated from the particles by shearing from the weight before and after the agitation as an index of the mechanical strength. That is, about 2 g of freeze-dried particles are placed in a beaker, and 500 ml of 2N-NaOH is charged. Stir at 500 rpm for 2 hours with a stirrer having 7 cm rotating blades. Keep the temperature of the system at 25 ° C. After stirring, the mixture is filtered with a 40-mesh stainless steel metal, washed with a large amount of water, dried with hot air, and weighed.

As is apparent from this result, particles having a large weight loss have low strength, and particles having a small weight loss have high strength. As other physical properties, for example, the amount of water retention varies depending on the size of the particles and the structure of the pores, but from 4 g to 1 g of particles.
12g.

The particles of the present invention have the basic structure as described above, and are particularly excellent in fluidity and workability since they have a large diameter. In addition, due to the continuous pore structure of large pores, mass transfer is quick and the speed of immobilization of cells, immobilization of an adsorbent, ion exchange reaction, etc. is high and efficiency is high. In addition, the large pore structure greatly improves the point that the microstructure changes during drying and the amount of water retention, the amount of chemicals, and the amount of ion exchange are remarkably reduced when reswelling.

In addition, the amount of ion exchange and the amount of immobilization are generally slightly smaller than those of the conventional porous cellulose particles having a large number of small-diameter pores as in the conventional product despite having a large number of pores inside. In addition, the strength is improved, and the weight loss due to stirring during the reaction and culture is reduced. In addition, the amount of bacteria immobilized is greatly affected by factors other than the surface area, and there are many cases where the structure of the present invention in which the internal surface area is suppressed has a larger amount of immobilization and higher adhesion strength than cellulose particles having a large internal surface area. .

As described above, the cellulose porous spherical particles of the present invention have conditions that allow industrial mass-use such as for an ion exchanger for an immobilized carrier, and are stable to chemicals because they are cellulose. It has the property of no toxicity and can be widely used in industrial fields such as pharmaceuticals and foods.

The method for producing the porous cellulose particles of the present invention is not limited at all, but a preferred production method will be described below.

In this production method, in principle, viscose and calcium carbonate are mixed, the mixed solution is pressurized, extruded in the form of droplets from a nozzle, dropped on a coagulation / regeneration bath, and coagulated / regenerated with cellulose in the form of droplets. This is a method in which calcium carbonate is acid-decomposed simultaneously, and if necessary, desulfurization, bleaching, washing and drying are performed.

In the present specification, the size of the particle diameter, the pore diameter, and the like are indicated by the diameter of the largest sphere or circle entering the sphere or circle if they are not spheres or circles.

In this method, viscose and calcium carbonate are first mixed to prepare a viscose liquid containing calcium carbonate. The solution is pressurized and extruded through a nozzle into droplets, and the droplets are dropped onto a coagulation / regeneration bath. Thereafter, stirring is performed for a predetermined time to produce cellulose porous particles having an internal pore structure according to each viscose condition, coagulation / regeneration condition, and the like.

The viscose used has, for example, the following properties.
The cellulose concentration is 3 to 15% by weight (hereinafter represented by wt%), preferably 4 to 10% by weight. The ammonium chloride value is from 3 to 12, preferably from 4 to 9. The alkali concentration is 2 to 15% by weight, preferably 5 to 13% by weight as caustic soda.

Viscose has a viscosity of 50 centipoise to 1 at 20 ° C.
0,000 centipoise, preferably 100 centipoise to 7,000
It is centipoise.

At this time, if the cellulose concentration, ammonium chloride value and alkali concentration are out of the above-mentioned predetermined ranges, the following undesirable causes are caused. That is, when the cellulose concentration is low, the mechanical strength of the prepared particles is low, and when the cellulose concentration is high, the viscosity of the liquid is increased and the discharge from the nozzle is not uniform, resulting in irregular particles. When the ammonium chloride value is high, the shape of the produced particles becomes irregular and irregular. On the other hand, when the particle size is low, the mechanical strength of the particle surface is weak, and the surface is broken during stirring to reduce the particle size. Also, when the alkali concentration is high, the particle shape tends to be distorted, and when the alkali concentration is low, the surface is easily broken during stirring.

The calcium carbonate used is not particularly limited, and may be light calcium carbonate or heavy calcium carbonate. Usually, those having an average particle size of 1 μm to 15 μm are used from the viewpoint of ease of mixing and workability such as nozzle clogging. The average pore size of the calcium carbonate does not significantly affect the internal pore structure of the porous cellulose particles. Calcium carbonate is 0.1% by weight of cellulose in viscose.
1 to 10 parts by weight, preferably 0.4 to 7 parts by weight is used. The amount of calcium carbonate does not change the basic internal pore structure of the particles, and contributes to the number of pores, particularly the generation of fine pores of 30 μm or less, and the relation that the number of pores increases as the amount of calcium carbonate increases. .

The mixing of viscose and calcium carbonate is carried out by stirring with a stirrer or a kneader, and the calcium carbonate powder may be directly added to the viscose being stirred, or the calcium carbonate powder may be dispersed in water in advance, and the dispersion may be added. You can add it.

The pressurization may be performed by any method as long as the discharge pressure from the nozzle hardly fluctuates, but pressurization by a gear pump and pressurization by air pressure are industrially advantageous.
The pressure at the time of pressurization may be a pressure at which the mixed liquid can be discharged from the nozzle.

The nozzle may have a diameter of 0.1 mm or more, and there is no particular limitation on the material and shape. If the diameter is smaller than 0.1 mm, the nozzle is easily clogged, and the productivity is poor. Also, small particles such as those produced with a nozzle having a diameter of less than 0.1 mm are not the object of the present invention.

Coagulation and regeneration agents that coagulate and regenerate cellulose and acid-decompose calcium carbonate as a foaming agent include hydrochloric acid, phosphoric acid,
Inorganic acids such as carbonic acid and sulfuric acid are used, but hydrochloric acid is preferred. It is not only advantageous from the viewpoint of productivity that installing a plurality of coagulation / regeneration baths but using a plurality of coagulation / regeneration baths in series or in parallel is advantageous from the viewpoint of productivity. This is also advantageous in that particles having an internal pore structure different from those prepared in individual baths can be produced. The concentration of acid in the coagulation / regeneration bath is usually 10 g / l to 90 g / l, preferably 15 g / l to 70 g / l, in the case of hydrochloric acid.The salt concentration in the bath is calcium chloride and sodium chloride. Is from 0 to 400 g / l, more preferably from 100 to 200 g / l. Coagulation / regeneration bath temperature is usually 10
-50 ° C, more preferably 20-40 ° C.

According to the production method of the present invention, by adjusting the ammonium chloride value of viscose, the concentration of acid in the coagulation / regeneration bath, the temperature of the bath, and the concentration of salt, cellulose porous particles having various internal pore structures can be obtained. Can be created. As described above, in the production method of the present invention, the ammonium chloride value of viscose is usually 3 to 3.
12, the concentration of acid in the coagulation / regeneration bath is 10 g / l to 90 g in the case of hydrochloric acid
/ l, bath temperature is 10-50 ℃, salt concentration in bath is 0-400g in total when calcium salt and sodium chloride are used.
Prepare cellulose porous particles under the condition of / l. At this time, when the cellulose particles are prepared under conditions in which the coagulation / regeneration reaction of cellulose progresses slowly, that is, viscose having a high ammonium chloride value (so-called ripening has not progressed), a low acid concentration, a high salt concentration and a bath. When a low-temperature coagulation / regeneration bath is used in combination, the resulting porous cellulose particles have large pores with a diameter of 150 μm or more, and the large internal surface area of the partition walls is not so large. Can be

The production conditions in this case are usually a viscose ammonium chloride value of 7 to 11 and a coagulation / regeneration bath acid concentration of 20 to 40 with hydrochloric acid.
g / l, salt concentration is 200-400g / l in total of sodium chloride and calcium chloride. FIGS. 1 and 2 show scanning electron micrographs of porous cellulose particles having an internal pore structure of this type. FIG. 1 is a photograph of the surface and FIG. 2 is a photograph of the cross section at the center.

In the above method, when the solidification / regeneration reaction is performed under a condition that proceeds a little more quickly, the diameter of the pores is slightly smaller and the number thereof is larger, and the thickness of the partition walls is also slightly smaller.

The pore size of the porous cellulose particles obtained by this method is slightly reduced as compared with the above case, but the number is slightly larger. Scanning electron micrographs of particles of this type are shown in FIGS. 3 and 4.

The production conditions are usually a viscose ammonium chloride value of 6-8.
The coagulation / regeneration bath acid concentration is 30-60 g / l with hydrochloric acid and the salt concentration is 150-250 g / l in total of sodium chloride and calcium chloride.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to examples.

Example 1 Viscose 40 having 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%.
0 g and 37 g of calcium carbonate (Nitto Powder Chemical Co., Ltd. SS ^# 30 average particle size 7.4 μm) are placed in a beaker and mixed with a stirrer.
The mixture was stirred at 0 rpm for 20 minutes to prepare a viscose solution containing calcium carbonate. Then, a viscose liquid is sucked from a beaker by a tube pump (Micro Tube Pump MP-3, Tokyo Rikakiki Co., Ltd.) and pressurized, and at a speed of 5 cc / min from a discharge port in which five 1.2 mm diameter injection needles are incorporated. The mixture was extruded in the form of droplets and dropped on a 5 l beaker serving as a coagulation / regeneration bath. Hydrochloric acid concentration of coagulation / regeneration bath is 25 g / l, temperature is 25
℃, salt concentration is the sum of sodium chloride and calcium chloride
It was 250 g / l. It took about 1 hour from the time when the droplet started to be dropped into the 5 l beaker, which is a coagulation / regeneration bath, to the end of the dropping, and thereafter, the coagulation / regeneration of cellulose and the acid decomposition of calcium carbonate were performed for 2 hours. Care was taken to constantly stir the coagulation / regeneration bath to ensure uniform coagulation / regeneration / acid decomposition.

Then wash with a large excess of water, 2 g / l caustic soda and 2 g / l
In a desulfurization bath containing sodium sulfide at 70 ° C. for 1 hour. After that, it is washed with a large excess of water, then bleached in a bleach bath containing 2.6 g / l of sodium hypochlorite at 20 ° C for 20 minutes, and washed again with a large excess of water to remove the cellulose porous particles. Obtained. The shape of the obtained particles is an average particle size of 3.
It was a 4 mm spherical particle. FIGS. 1 and 2 show scanning electron micrographs of the obtained particles. FIG. 1 shows the surface, FIG.
The figure is a central section.

Example 2 The viscose used was a cellulose concentration of 9.2% and a viscosity of 5,200.
Centipoise, ammonium chloride value 6.8, alkali concentration
6.3%, and the coagulation / regeneration bath conditions used were a hydrochloric acid concentration of 33 g.
Cellulose porous particles were obtained in the same manner as in Example 1 except that the temperature was 30 ° C., and the salt concentration was 150 g / l in total of sodium chloride and calcium chloride. The shape of the obtained particles was spherical particles having an average particle diameter of 3.2 mm in a water-swelled state. FIGS. 3 and 4 show scanning electron micrographs of the obtained particles.

[Brief description of the drawings]

1 to 4 show the particle structure of the cellulose porous particles.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08B 16/00 C08B 16/00 G01N 30/48 G01N 30/48 D

Claims (1)

(57) [Claims] (A) a cellulose comprising (A) cellulose; (B) a sphere having a diameter of 0.5 mm or more when swollen with water;
(C) The interior is composed of pores and partition walls, and a large number of holes are randomly mixed in large and small sizes to form a spherical shape. And one of the holes has a diameter of about 15 at a substantially central section on the short diameter side of the hole.
0 μm or more, it has a substantially circular or polygonal shape, and the holes communicate with some or all of the adjacent holes by small holes or cracks penetrating the partition walls. (D) Partially continuous holes as a whole Cellulose porous spherical particles having a porous structure.