JP2564201B2 - Method for producing cellulose porous particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a porous cellulose particle.

[Prior Art] Cellulose particles have been used in various fields as a carrier for immobilizing cells / enzymes, a carrier for adsorbing perfume / chemicals, a cosmetic additive, and various ion exchangers by introducing various functional groups. It is becoming widely used. The shape of the cellulose particles is excellent in fluidity in any application, and a spherical shape having mechanical strength is advantageous. In addition, generally, the amount of immobilized or adsorbed bacterial enzyme, the amount of drug, and the number of functional groups that can be introduced are proportional to the surface area and the internal surface area of the particle. Therefore, it is advantageous to make the particles porous. For this reason, much research has been conducted to date on spherical spherical particles or porous spherical particles.

For example, Japanese Unexamined Patent Publication (Kokai) No. 48-60753 discloses a method in which viscose is discharged in the form of droplets to coagulate and regenerate to obtain porous cellulose particles of 16 to 170 mesh. However, particles having voids inside cannot be obtained by this method.

In Japanese Examined Patent Publication No. 57-7162, the apparent density is 0.4 g / cm ³ or less.
Hollow cellulosic fine particles having a large void in the center of 16 to 170 mesh are disclosed. These particles have the drawbacks that they are hollow, the entire particles do not have a porous structure, and the internal surface area cannot be large.

Japanese Examined Patent Publication (Kokoku) No. 57-45254 discloses that a viscose suspension is heated and solidified in chlorobenzene with continuous stirring to obtain a particle mixture containing particles having a particle size of 150 to 350 μm as a main component. ing. With this method, it is possible to create an uneven surface, but not an internal hole.

In Japanese Patent Laid-Open No. 63-90501, first, an anionic water-soluble polymer compound is mixed with a mixture of viscose and a water-soluble polymer compound to prepare a fine particle dispersion, which is heated or coagulated with a coagulant and then acidified. Regeneration, then water-soluble polymer is removed in the steps of coagulation, regeneration, and water washing, and the average particle size is 300 μm or less
Disclosed is a method of obtaining porous microcellulose particles having a maximum pore volume in a section of 0.02 to 0.8 μm and a total pore volume of pores in the section being 0.025 ml / g or more. The particles produced by this method are such that minute particles have minute pores. Further, in JP-A-63-92602, viscose, calcium carbonate, and a water-soluble anionic polymer compound are mixed to prepare a viscose fine particle dispersion containing calcium carbonate, which is coagulated A method for obtaining porous spherical cellulose particles by solubilization and then acid decomposition of calcium carbonate is disclosed. In any of the above methods, very small particles have small pores, and large particles cannot have large pores.

Japanese Patent Application Laid-Open No. 64-43530 discloses a method in which a cellulose solution is made into droplets and the droplets are cooled and frozen, and then the solvent is extracted and removed or the dissolving ability is lost to obtain cellulose porous particles.

This method can also produce porous cellulose particles having a large number of pores inside with large particles, but there is a drawback that it takes time to freeze, coagulate and regenerate.

[Problems to be Solved by the Invention]

The object of the present invention is to provide large particles (having a diameter of 0.
(5 mm or more) to provide a new method for producing porous cellulose particles having a large number of pores inside. Another object of the present invention is to provide a method capable of producing several types of cellulose porous particles having different internal pore structures.

[Means for solving the problem]

The above problems are as follows. Cellulose concentration is 3 to 15% by weight, viscosity at 20 ° C is 50 to 10,000 centipoise, ammonium chloride value is 3 to 12, and alkali concentration is caustic soda.
A solution containing 0.1 to 10 parts by weight of calcium carbonate per 1 part by weight of cellulose in 15 to 15% by weight of viscose is extruded from a nozzle having a diameter of 0.1 to 10 mm, and a hydrochloric acid content of 10 is obtained. It is solved by dropping into a hydrochloric acid solution having a liquid temperature of 20 to 40 ° C. at a temperature of 90 g / l and simultaneously promoting coagulation and regeneration of cellulose and acid decomposition of calcium carbonate.

In the present specification, sizes such as particle diameters and pore diameters are indicated by the diameter of the largest sphere or circle that enters the sphere or circle if it is not a sphere or circle.

[Function and Configuration of the Invention]

In the method of the present invention, first, viscose and calcium carbonate as a foaming agent are mixed to prepare a viscose liquid containing calcium carbonate. The solution is pressurized, extruded through a nozzle, and dropped in the form of droplets onto a coagulation / regeneration bath. Then, the method is a method for producing cellulose porous particles having an internal pore structure according to each viscose condition and coagulation / regeneration condition by stirring for a predetermined time.

The viscose used has the following properties. The cellulose concentration is 3 to 15% by weight (hereinafter referred to as wt%), preferably 4 to 10% by weight. Ammonium chloride value is 3-12
Preferably it is 4-9. The alkali concentration of caustic soda is 2 to 15 wt%, preferably 5 to 13 wt%.

Viscose viscosity is 50 centipoise ~ 1 at 20 ℃
0,000 centipoise, preferably 100 centipoise to 7,000
It is a centipoise.

At this time, if the cellulose concentration, the ammonium chloride value and the alkali concentration are out of the above predetermined ranges, the following undesirable causes will occur. That is, when the concentration of cellulose is low, the mechanical strength of the produced particles becomes small, and when it is high, the viscosity of the liquid increases and the ejection from the nozzle becomes uneven, resulting in irregular particles. When the ammonium chloride value is high, the shape of the particles produced becomes distorted and not constant. On the other hand, if it is low, the mechanical strength of the surface of the particles is weak and the surface is crushed and becomes small during stirring. Also, when the alkali concentration is high, the particle shape is likely to be distorted, and when the alkali concentration is low, the surface is easily broken during stirring.

The calcium carbonate used as a foaming agent 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 easiness of mixing and workability such as nozzle clogging. The average particle size of the calcium carbonate does not significantly affect the internal pore structure of the cellulose porous particles. Calcium carbonate is used in 0.1-10 parts by weight, preferably 0.4-7 parts by weight, per 1 part by weight of cellulose in viscose. The amount of calcium carbonate does not change the basic internal pore structure of the particles and is involved in the number of pores, especially the formation of fine pores of 30 μm or less, and the relationship is that the number of pores increases as the amount of calcium carbonate increases. .

The viscose and calcium carbonate can be mixed by stirring with a stirrer or a kneader, and the calcium carbonate powder may be added directly to the stirring viscose, or the calcium carbonate powder can be dispersed in water beforehand and the dispersion liquid You can add it.

The pressurization may be performed by any method as long as the discharge pressure from the nozzle does not easily change, 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 above mixed liquid can be discharged from the nozzle.

The nozzle has a diameter of 0.1 to 10 mm, and there is no particular restriction on the material and shape. If the diameter is smaller than 0.1 mm, the nozzle will be easily clogged and the productivity will be poor. Also, small particles such as those produced with nozzles having a diameter smaller than 0.1 mm are not the object of the present invention. In the present invention, it is sufficient that the above-mentioned mixed liquid is in the form of droplets when entering the coagulation / regeneration bath, and it is not necessarily required to be in the form of droplets from the discharge port of the nozzle.

Hydrochloric acid is used as a coagulation / regeneration agent for coagulation / regeneration of cellulose and acid decomposition of calcium carbonate as a foaming agent. 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 hydrochloric acid in the coagulation / regeneration bath is preferably 10 g / to 90 g / more preferably
The concentration of salt in the bath is 15 g / -70 g / calcium chloride and sodium chloride, the sum of the two being 0-400 g / more preferably 100-200 g /. Coagulation / regeneration bath temperature is 20-40
° C.

In the present invention, desulfurization, bleaching, washing with water, and drying are then carried out if necessary. These treatments are performed by a conventional method.

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
12, the concentration of hydrochloric acid in the coagulation / regeneration bath is 10g / l ~ 90g / l, the bath temperature is
The cellulosic porous particles are prepared under the conditions of 20 to 40 ° C., and the salt concentration in the bath is 0 to 400 g / in total when the salt types are calcium chloride and sodium chloride. At this time, when the cellulose particles are prepared under the condition that the coagulation / regeneration reaction of the cellulose proceeds rapidly, for example, viscose having a low ammonium chloride value (so-called matured) and a high acid concentration and a low salt concentration and a bath temperature of When used in combination with a high coagulation / regeneration bath, the resulting cellulose porous particles are 15
A large number of thin and small-diameter holes of partition walls of 0 μm or less extend radially from the inside to the surface, resulting in a large internal surface area. In this case, the production conditions are usually viscose ammonium chloride value of 4 to 6.5 and coagulation / regeneration bath acid concentration of hydrochloric acid is 50 to 80 g.
/, The salt concentration is 0-200 g / in total of sodium chloride and calcium chloride.

Scanning electron micrographs of cellulose porous particles having this type of internal pore structure are shown in FIGS. 1 and 2.
FIG. 1 is a surface photograph, and FIG. 2 is a cross-sectional photograph of the central portion.

On the contrary, when the condition that the coagulation / regeneration reaction of cellulose proceeds slowly is used, that is, viscose with a high ammonium chloride value (so-called unaged) and low acid concentration, high salt concentration and low bath temperature coagulation / When used in combination with a regenerating bath, the resulting cellulose porous particles are 150 μm
Since a plurality of large-diameter holes as described above are formed, the thick internal surface area of the partition wall is not so large.

In this case, the production conditions are usually viscose ammonium chloride value of 7 to 11 and coagulation / regeneration bath acid concentration of 20 to 40 with hydrochloric acid.
g /, the salt concentration is 200-400g / in total of sodium chloride and calcium chloride. Scanning electron micrographs of the cellulose porous particles having this type of internal pore structure are shown in FIGS. 3 and 4. FIG. 3 is a surface photograph, and FIG. 4 is a cross-sectional photograph of the central portion.

The cellulose porous particles produced under the above two intermediate reaction conditions have two intermediate internal pore structures.
Scanning electron micrographs of particles of this type are shown in FIGS. 5 and 6.

Manufacturing conditions are usually viscose ammonium chloride value 6-8
Coagulation / regeneration bath Acid concentration is 0-60 g with hydrochloric acid / Salt concentration is 150-250 g / with the total of sodium chloride and calcium chloride.

Cellulose porous particles other than these three types can be produced by using a combination of the above conditions and a plurality of coagulation / regeneration baths having different acid concentrations.

The cellulose porous particles thus produced are granular particles having a generally spherical to elliptical shape, and the size of the particles themselves is usually 0.5 mm to 10 mm when swollen with water. The surface may or may not have a thin film formed, and a large number of pores are present inside, making it extremely porous as a whole.

Due to such a structure, it can be used extremely effectively for a carrier for immobilizing cells / enzymes, a carrier for adsorbing a fragrance / drug, a cosmetic additive, an ion exchanger, and various other conventionally used applications. .

〔The invention's effect〕

Various cellulose porous particles obtained by the production method of the present invention are used for applications such as carriers for immobilizing cells and enzymes or carriers for adsorbing ion exchangers, perfumes, chemicals, etc. depending on the internal pore structure. It is possible, and the industrial effect is extremely large.

〔Example〕

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

Example 1 Viscose 40 having a cellulose concentration of 9.2%, a viscosity of 5.000 centipoise, an ammonium chloride value of 5.8, and an alkali concentration of 6.2%.
0 g and 37 g of calcium carbonate (SS ^# 30 average particle size 7.4 μm of Nitto Koka Kogyo Co., Ltd.) were placed in one beaker and stirred with a stirrer to 70
Stirring was carried out at 0 rpm for 20 minutes to prepare a viscose solution containing calcium carbonate. After that, the tube pump (Tokyo Rika Kikai Co., Ltd. micro tube pump MP-3) sucks and pressurizes the viscose solution from the beaker, and at the speed of 5 cc / min from the discharge port incorporating five 1.2 mm diameter needles. It was extruded in the form of droplets and dropped onto 5 beakers that were used as a coagulation / regeneration bath. The concentration of hydrochloric acid in the coagulation / regeneration bath is 70 g /, the temperature is 30
℃, salt concentration is the total of sodium chloride and calcium chloride
It was 30 g /. It took about 1 hour from the time when the droplets started to be dropped into the 5 beakers as the coagulation / regeneration bath to the end of the dropping, and then the coagulation / regeneration of cellulose and the acid decomposition of calcium carbonate were carried out for 2 hours. The coagulation / regeneration bath was constantly stirred to ensure uniform coagulation / regeneration / acid decomposition.

Then washed with a large excess of water, 2 g / caustic soda and 2 g /
Was desulfurized at 70 ° C. for 1 hour in a desulfurization bath containing sodium sulfide. Then washed with a large excess of water, then bleached in a bleaching bath containing 2.6 g / sodium hypochlorite at 20 ° C for 20 minutes, and washed again with a large excess of water to obtain cellulose porous particles. It was The shape of the obtained particles was spherical particles having an average particle diameter of 3.5 mm when swollen in water. Scanning electron micrographs of the obtained particles are shown in FIGS. 1 and 2. Figure 1 shows the surface,
FIG. 2 is a central section.

Example 2 The viscose used had a cellulose concentration of 9.0% and a viscosity of 4,500.
Centipoise, ammonium chloride value 8.5, alkali concentration
6.1%, the coagulation / regeneration bath conditions used were hydrochloric acid concentration 2
Cellulose porous particles were obtained in the same manner as in Example 1 except that the concentration was 5 g /, the temperature was 25 ° C., and the salt concentration was 250 g / in total of sodium chloride and calcium chloride. The shape of the obtained particles was spherical particles having an average particle diameter of 3.4 mm in a water swollen state. Scanning electron micrographs of the obtained particles are shown in FIGS. 3 and 4.

Example 3 The viscose used had a cellulose concentration of 9.2% and a viscosity of 5,200.
Centipoise, ammonium chloride value 6.8, alkali concentration
6.3%, the coagulation / regeneration bath conditions used were hydrochloric acid concentration 33 g
Cellulose porous particles were obtained in the same manner as in Example 1 except that the temperature was 30 ° C., the salt concentration was 150 g / 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 when swollen in water. Scanning electron micrographs of the obtained particles are shown in FIGS. 5 and 6.

[Brief description of drawings]

1 to 6 all show the particle structure of the cellulose porous particles.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B01J 20/24

Claims (1)

(57) [Claims] 1. A cellulose concentration of 3 to 15% by weight, a viscosity at 20 ° C. of 50 to 10000 centipoise, an ammonium chloride value of 3 to 12, and an alkali concentration of 2 to 1 as caustic soda.
A solution containing 0.1 to 10 parts by weight of calcium carbonate per 1 part by weight of cellulose in 15% by weight of viscose is extruded from a nozzle having a diameter of 0.1 to 10 mm to form a liquid drop having a hydrochloric acid content of 10 to 10 A method for producing porous cellulose particles, which comprises dropping into a hydrochloric acid solution having a liquid temperature of 20 to 40 ° C. at 90 g / l to simultaneously proceed with coagulation regeneration of cellulose and acid decomposition of calcium carbonate.