JPH05339115A - Antimicrobial porous cellulose and its production - Google Patents

Abstract

PURPOSE:To provide antimicrobial material where most of antimicrobial particles employed develop effectively their antimicrobial or microbicidal action and do not leak off from the cellulose substrate, thus it can be used in cleaning water, oil, air or the like. CONSTITUTION:A mixture of viscose, antimicrobial particles and acidolytic foaming agent is fed into the coagulation-regeneration bath to cause the viscose to be coagulated and regenerated, as the foaming is effected, to give antimicrobial porous cellulose which is composed of the cellulose skeleton 1 having pores 3 smaller than the size of the antimicrobial particles 2 where the particles are held by the pores in the skeleton.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous cellulose having antibacterial and bactericidal effects and a method for producing the same.

[0002]

2. Description of the Related Art Inorganic antibacterial agent particles having an antibacterial and bactericidal action, for example, zeolite carrying silver, copper, tin and other metals having an antibacterial and bactericidal action are safer than organic ones. Therefore, it is being widely used for water treatment such as purification of drinking water and cooling water, oil treatment for purification of lubricating oil and solvent, and antibacterial and deodorization of indoor air.

By the way, conventionally, the antibacterial agent particles have been used by kneading them in a plastic material such as polyethylene or vinyl chloride, or by accumulating them in a binder such as starch, or after-processing into paper, non-woven fabric, woven fabric, etc. It is used by simply attaching it.

[0004]

However, in the case where the antibacterial agent particles are kneaded in the plastic material, among the contained antibacterial agent particles, only those exposed on the surface are contacted with the liquid to be treated, etc. Since it does not exert a bactericidal action and most of it is embedded in the plastic material and does not come into contact with the liquid to be treated, it does not exert an antibacterial action or a bactericidal action.

Therefore, the one in which the antibacterial agent particles are kneaded in the plastic material has a problem that the use efficiency of the expensive antibacterial agent particles is poor.

Therefore, it is possible to use a porous plastic material in order to increase the number of antibacterial agent particles exposed on the surface. However, since most plastic materials are hydrophobic, water treatment is not possible. Water is repelled and the water does not penetrate inside, and the reactivity with the antibacterial agent particles exposed on the surface is not good.

Next, when the antibacterial agent particles are hardened with a binder such as starch, the antibacterial agent particles are covered with the binder, so that the contact between the antibacterial agent particles and the liquid to be treated is reduced and the antibacterial and sterilization is performed. The effect is inferior. In addition, in this case, since the particles easily collapse, a problem of powder leakage of the antibacterial agent particles occurs.

Next, when the antibacterial agent particles are used after being attached to paper, non-woven fabric, woven cloth, etc. by post-processing, the antibacterial agent particles are likely to be peeled off, and there is a problem that the antibacterial agent particles are leaked.

Therefore, the present invention has a technical object to solve most of the problems that most of the antibacterial agent particles to be used effectively exhibit antibacterial and bactericidal effects and that the antibacterial agent particles are leaked. ..

[0010]

According to the present invention, the skeleton of a porous body having a large number of pores is made of cellulose, and the skeleton portion in which pores having a diameter smaller than that of the antibacterial agent particles are gathered is antimicrobial agent particles. The above-mentioned problems are solved by the antibacterial porous cellulose that retains.

The above-mentioned antibacterial porous cellulose is mixed with viscose, antibacterial agent particles and an acid-decomposable foaming agent, and the mixture is supplied to the coagulation / regeneration bath to foam in the coagulation / regeneration bath. It can be obtained by performing coagulation regeneration of cellulose while foaming the material.

[0012]

[Function] Cellulose, which forms the skeleton of the porous body, is hydrophilic and has a large number of pores. Therefore, when it is used for water treatment, water permeates the inside and contacts the antibacterial agent particles inside. Therefore, the use efficiency of the antibacterial agent particles is good.

Further, since the pore diameter of the skeleton portion holding the antibacterial agent particles is smaller than the diameter of the antibacterial agent particles, the antibacterial agent particles do not leak out.

[0014]

EXAMPLE A conceptual view of the antibacterial porous cellulose of the present invention is as shown in FIG. 1, in which the skeleton 1 of the porous body having a large number of pores is composed of cellulose, and The antibacterial agent particles 2 are held in a skeleton portion in which pores 3 having a small diameter are gathered.

The total pores of the porous body have a pore size distribution and a pore volume determined by a mercury porosimeter method, and pores having a pore size of 0.1 μm or more occupy 80% or more of the total pore volume. Moreover, it is preferable that the pore volume is 0.5 cc / g or more.

This is because if the proportion of particles having a diameter of 0.1 μm or less accounts for 20% or more, the fluid to be treated is less likely to permeate between the skeletons 1 and is less likely to come into contact with the antibacterial particles 2 between the skeletons 1. .. Further, even if it is 0.5 cc / g or less, the permeability of the fluid to be treated becomes poor.

As the antibacterial agent particles 2, it is possible to use antibacterial agent particles in which a metal ion having an antibacterial property is supported on an inorganic carrier having a capacity of ion exchange such as zeolite or silica gel. A particle size of 1 to 20 μm is preferable.

The antibacterial metal includes silver, copper, zinc, mercury, tin and the like, and silver, copper and zinc are usually used. In addition, the amount of the metal to be supported by the inorganic system varies depending on the type of the metal and the bacteria or fungi to be sterilized.

The blending ratio of the cellulose and the antibacterial agent particles 2 may be appropriately selected according to the purpose, but in the case of the inorganic antibacterial agent particles carrying 5% of silver ions, from the viewpoint of cost. Usually, it is 20% or less of cellulose.

Reinforcing fibers such as rayon, polyester, vinylon, cellulose, etc. are added to the cellulose forming the porous body.
Wood pulp, hemp, polypropylene, nylon, etc. may be mixed. As the type of the reinforcing fiber, rayon, vinylon, wood pulp, hemp, etc. are usually used in consideration of the compatibility with viscose, good adhesiveness and the like.

The form of the antibacterial porous cellulose of the present invention includes beads, sheets, blocks, or laminated products with a base material such as non-woven fabric or paper, and is packed in a column for sterilization by passing a liquid or a filter. It can be used as an air purifier or by being attached to a casing.

The antibacterial porous cellulose of the present invention can be manufactured as follows.

First, a mixed solution is prepared by mixing viscose, antibacterial agent particles, and an acid-decomposable foaming agent. When the reinforcing fiber is mixed with the cellulose, the reinforcing fiber is mixed in this mixed solution.

Next, the above-mentioned mixed liquid is supplied to a coagulation / regeneration bath, coagulation / regeneration of cellulose and acid decomposition by a foaming agent are simultaneously carried out in the coagulation / regeneration bath, and thereafter, desulfurization, bleaching, washing with water and drying are carried out as required. ..

When the above mixed solution is supplied to the coagulation / regeneration bath, when the mixed solution is supplied in the form of droplets from a nozzle, granular, that is, beads of antibacterial porous cellulose are obtained. Further, when the mixed solution is extruded from the slit and supplied in a sheet form to the coagulation / regeneration bath, a sheet-like antibacterial porous cellulose is obtained. In addition, the above mixed solution with a roll coater or the like,
When coated or impregnated on a substrate such as a non-woven fabric, paper or woven fabric and then supplied to a coagulation / regeneration bath, a laminate of the antibacterial porous cellulose and the substrate is obtained. Further, when the mixed solution is made into blocks and supplied to the coagulation / regeneration bath, block-shaped antibacterial porous cellulose is obtained.

As the viscose used in the present invention, those industrially manufactured from wood pulp can be used.

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

The viscosity of viscose at 50 ° C. is from 50 centipoises to 10,000 centipoises, preferably 10 centipoises.
It is from 0 to 7,000 centipoise.

At this time, if the cellulose concentration, the ammonium chloride value and the alkali concentration are out of the above-mentioned predetermined ranges, the following undesirable causes will occur. That is, when the concentration of cellulose is low, the mechanical strength of the prepared one becomes small, and when it is high, the viscosity of the liquid increases, and when the beads are formed, the ejection from the nozzle is not uniform and the particles become irregular. 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 during stirring and becomes small. Also, when the alkali concentration is high, the particle shape tends to be distorted, and when the alkali concentration is low, the surface is likely to be broken during stirring.

Considering the price and the stability in viscose, calcium carbonate is preferably used as the foaming agent.

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 20 μm are used from the viewpoint of ease of mixing and workability such as nozzle clogging.

The viscose, the antibacterial particles 2 and the calcium carbonate may be mixed by stirring with a stirrer or a kneader, and the antibacterial particles 2 and the calcium carbonate powder may be added directly to the viscose during stirring. The antibacterial particles 2 and the calcium carbonate powder may be previously dispersed in water and the dispersion may be added.

When forming beads, any method may be used as long as the discharge pressure from the nozzle does not fluctuate, but pressure by a gear pump and pressure by air pressure are industrially advantageous. Is. The pressure during pressurization is
The pressure at which the above mixed liquid can be discharged from the nozzle may be used.

Hydrochloric acid is used as a coagulation / regeneration agent for coagulation / regeneration of cellulose and acid decomposition of calcium carbonate as a foaming agent,
Inorganic acids such as phosphoric acid, carbonic acid and sulfuric acid are used, but hydrochloric acid is preferred. It is more advantageous from the viewpoint of productivity to install a plurality of coagulation / regeneration baths and use them in series or in parallel. If the conditions of each coagulation / regeneration bath are changed,
It is also advantageous in that it is possible to produce particles having an internal pore structure different from that produced by one bath. The concentration of acid in the coagulation / regeneration bath is usually 10 g / l to 90 g / l in the case of hydrochloric acid.
The concentration of the salt in the bath is more preferably 15 g / l to 70 g / l and the total of the two is 0 to 400 g / l, more preferably 100 to 200, in the ratio of calcium chloride and sodium chloride.
g / l. The coagulation / regeneration bath temperature is usually 10 to 50 ° C, and more preferably 20 to 40 ° C.

[Experimental Example 1] Viscose 200 for producing cellophane having a cellulose concentration of 9.0% and an alkali concentration of 6.3%.
g and calcium carbonate (Nitto Koka Kogyo, SS ^# 30) 5
4 g and 0.18 g of zeolite-based antibacterial agent particles (average particle size 2 μm, 3% and 6% by weight of silver and copper as antibacterial metal ions, respectively) were placed in a 1 liter beaker and stirred for 1 hour. Stir to form a mixture.

The mixed solution is pressurized with a pump to have a caliber of 0.5.
It was discharged from an injection needle of mm and dropped in a droplet form in the coagulation / regeneration bath.

The coagulation / regeneration bath had a hydrochloric acid concentration of 70 g / l and a temperature of 40 ° C.

Thereafter, the mixture was stirred for 1 hour, transferred to a 5 l beaker and washed with a large excess of water to obtain beads of antibacterial porous cellulose.

The pore structure of the obtained beads (average particle diameter of 2 to 3 mm in a water swollen state) was measured by a mercury porosimeter, and the proportion of pores larger than 0.1 μm in all pores was 98. % And the pore volume is 5 cc / g
Met.

[Experimental Example 2] Viscose 200 for producing cellophane having a cellulose concentration of 9.0% and an alkali concentration of 6.3%.
g and calcium carbonate (Nitto Koka Kogyo, SS ^# 30) 5
4 g and 0.18 g of zeolite-based antibacterial agent particles (average particle size 2 μm, 3% and 6% by weight of silver and copper as antibacterial metal ions, respectively) were placed in a 1 liter beaker and stirred for 1 hour. Stir to form a mixture.

This mixed solution was pressurized with a pump and extruded from a slit having a width of 3 mm and a length of 50 cm, and put into a coagulation / regeneration bath in a sheet form.

The coagulation / regeneration bath had a hydrochloric acid concentration of 70 g / l and a temperature of 40 ° C.

Thereafter, the sheet was washed with a large excess of water to obtain a sheet-shaped antibacterial porous cellulose.

The obtained sheet is finely cut into 2-3 m
/ M cut into pieces (thickness is 2-3 m when swollen in water)
When the pore structure of m) was measured by a mercury porosimeter, the proportion of pores larger than 0.1 μm was 96% of the total pores, and the pore volume was 2.2 cc / g.

Comparative Example 1 Viscose 200 for producing cellophane having a cellulose concentration of 9.0% and an alkali concentration of 6.3%.
g and calcium carbonate (average particle size 0.5 μm) 1.8 g and zeolite antibacterial agent particles (average particle size 2 μm, silver and copper as antibacterial metal ions supported by 3% and 6% respectively by weight) Add 0.18g into a 1l beaker and stir 1
Stir for hours to form a mixture.

The mixed solution is pressurized with a pump to have a caliber of 0.5.
It was discharged from an injection needle of mm and dropped in a droplet form in the coagulation / regeneration bath.

The coagulation / regeneration bath had a hydrochloric acid concentration of 70 g / l and a temperature of 40 ° C.

Thereafter, the mixture was stirred for 1 hour, transferred to a 5 l beaker, and washed with a large excess of water to obtain beads of antibacterial porous cellulose.

The pore structure of the obtained beads (average particle size 2-3 mm in water swollen state) was measured by a mercury porosimeter. The proportion of pores larger than 0.1 μm in all pores was 50. % And the pore volume is 0.2 cc
/ G.

Comparative Example 2 A film having a thickness of 100 μm was prepared from polyethylene in which 1% by weight of the zeolite-based antibacterial agent particles used in Example 1 was kneaded, and cut into 2-3 mm holes as a sample.

[Comparative Example 3] A film having a thickness of 200 µm was prepared from polystyrene in which 1% by weight of the zeolite-based antibacterial agent particles used in Example 1 was kneaded, and the film was cut into 2-3 mm openings.

Comparative Example 4 Zeolite type antibacterial agent particles used in Example 1 were hardened with an acrylic binder to form particles having a diameter of 1 to 2 mm. The weight ratio of the zeolite-based antibacterial agent particles to the binder is 0.5: 1.
Is.

[Effect test] Six columns (18 mmφ × 80 mm) of the test apparatus shown in FIG.
Pack ~ 3 samples. Staphylococcus aureus is used as a test bacterium and adjusted so that the initial number of bacteria in the test solution is approximately 10 ⁶ / ml.

Then, the liquid is extracted with a pump at a rate of 1 l / min, circulated, and sampled at regular intervals. After that, the sampled solution is placed in a predetermined medium for 24 hours.
The number of colonies generated by time culturing was counted. The results are shown in Table 1.

The dry weights of the samples (Examples 1 and 2 and Comparative Example 4) packed in the column before and after the test were measured, and the ratio of the initial weight to the reduced weight was expressed as a percentage to obtain a powder. It was used as an indicator of leakage. The results are shown in Table 2.

In FIG. 2, reference numeral 4 denotes a column and 5
Is a sampling outlet, 6 is a thermostatic chamber, the temperature is 30 ° C., and 7 is a pump.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

INDUSTRIAL APPLICABILITY As described above, the antibacterial porous cellulose of the present invention has excellent antibacterial and bactericidal effects and does not cause powder leakage of antibacterial agent particles. Therefore, it is widely used for water treatment, oil treatment, air purification and the like. Can be used.

Further, since cellulose is biodegradable and can be incinerated, it is easy to treat after use and it is possible to prevent secondary pollution from occurring.

Further, since cellulose is safe in terms of food hygiene, it can be safely used in food related fields.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of antibacterial porous cellulose according to the present invention.

FIG. 2 is a schematic diagram of a test device.

[Explanation of symbols]

 1 skeleton 2 antibacterial agent particles 3 pores

Claims (8)

[Claims] 1. An antibacterial porous material in which the skeleton of a porous body having a large number of pores is made of cellulose, and the skeleton portion in which pores having a diameter smaller than that of the antibacterial agent particles are gathered holds the antibacterial agent particles. cellulose. 2. At least 80 of all the pores of the porous body.
% Has a diameter greater than 0.1 μm and the pore volume is 0.5 cc / g or more.
The antibacterial porous cellulose described. 3. The antibacterial agent particles are inorganic antibacterial agent particles in which a metal having antibacterial properties is carried on an inorganic carrier.
Or the antibacterial porous cellulose described in 2. 4. A mixed solution of viscose, antibacterial agent particles, and an acid-decomposable foaming agent is supplied to a coagulation / regeneration bath,
A method for producing antibacterial porous cellulose, which comprises coagulating and regenerating cellulose while foaming a foaming agent in a coagulation / regeneration bath. 5. A method for producing an antibacterial porous cellulose in which reinforcing fibers are mixed with the mixed liquid according to claim 4. 6. The method for producing an antibacterial porous cellulose according to claim 4, wherein calcium carbonate is used as the foaming agent. 7. The method for producing an antibacterial porous cellulose according to claim 4, wherein the mixed liquid is supplied in a droplet form to a coagulation / regeneration bath. 8. The method for producing an antibacterial porous cellulose according to claim 4, wherein the mixed solution is supplied in the form of a sheet to a coagulation / regeneration bath.