JP4166562B2 - Cellulosic material with large specific surface area - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to various cellulosic fibrils having a large specific surface area that are particularly necessary for improving substance adsorbability, substance separability, and chemical reactivity, and in particular, a microorganism-produced cellulosic fibril having a specific surface area of 55 m ² / g or more. And a sheet-like material mainly composed of the same.
[0002]
[Prior art]
The specific surface area of pulp, which is representative of woody cellulose, is 1 m ² / g or less. As a method for further microfibrillation, for example, a method of highly beating under water wetness or a method of forcibly sharing the aqueous dispersion through a thin slit is known.
In these methods, even when microfibrillation is achieved in a wet state, the specific surface area does not increase more than three times after drying and removing moisture, and the latter share is applied. Then, it is normally provided only in a state of never dry or impregnated with glycerin or the like.
[0003]
On the other hand, there is so-called bacterial cellulose produced by microorganisms. Patent Document 1 describes a method for drying bacterial cellulose produced by acetic acid bacteria and the dried product. In brief, the first claim discloses a method of adding a third component other than water and then dehydrating and drying, and the following claims define a hydrophilic liquid and a hydrophilic solid as the third component. Furthermore, in the text, water-soluble low molecules, water-soluble polymers, water-insoluble solids, and poorly water-soluble solids are introduced as hydrophilic solids.
In the same document, the freeze-drying method and the sequential organic solvent substitution method (that is, the method of alcohol substitution, then acetone substitution, finally substitution with hexane and the like, and drying) are energy consuming type or process. It is pointed out that is complicated.
Furthermore, claim 7 of the same document discloses spray drying, pressing, air drying, hot air drying, and vacuum drying as drying means.
[0004]
However, this document does not intend to use bacterial cellulose in a dry state in the first place, but intends to restore the dispersibility when the dried product is dispersed again in water or the like (during culture production). The specific surface area in the dry state is not described at all, and the third component remains in the dried product, and pure cellulose fibrils are not obtained.
By the way, it is known that the bacterial cellulose has a specific surface area of about 50 m ² / g if it is freeze-dried after purification and separation. However, since it consumes a lot of energy as described above, it is very disadvantageous in terms of cost. It is.
[0005]
Moreover, according to the announcement by Kugara (presenter) (Abstracts of Microsymposium of Cellulose Society VOL.7th P.1-7 “Development of New Materials Utilizing Fine Structure of Natural Cellulose” 2002), acetic acid bacteria are produced. the bacterial cellulose and then dried butanol substitutions, to obtain those having a specific surface area of about 70m ² / g, because butanol is less volatile, and a freeze drying method as the drying means, the result as an organic solvent Since a double method of a substitution method and a freeze-drying method is used, the method is complicated and not cost-effective.
By the way, a cellulosic material produced by acetic acid bacteria is well known as a food material “Nata de Coco”. As other industrial applications, its characteristic functions such as nano-level fibrillation, high water content, high crystallinity, high elasticity, high energy loss, high-capacity inorganic support, high transparency, etc. were utilized. Many uses have been proposed.
[0006]
For example, an acoustic diaphragm (Patent Document 2), a high-mechanical sheet (Patent Document 3), a wound dressing (Patent Document 4), a polyacetal or rubber reinforcing material (Patent Document 5, Patent Document 6), a living tissue substitute ( Patent Document 7), food material (Patent Document 8), anti-counterfeit paper (Patent Document 9), transparent transfer paper for electrophotography (Patent Document 10), paper made of colloidal silica / amphoteric starch / pulp / bacterial cellulose (Patent Document) 11), functional sheet containing 50% or more of fine particles (Patent Document 12), artificial soil composition (Patent Document 13), enzyme / microbe-immobilized carrier (Patent Document 14), filtration membrane (Patent Document 15), activated carbon Materials (Patent Document 16), concrete blend (Patent Document 17), thermal recording paper support (Patent Document 18), activated carbon-containing filter (Patent Document 19), low density smooth paper (Patent Document 20) The thermal transfer-receiving sheet (Patent Document 21), photographic printing paper support (Patent Document 22) have been proposed.
However, all of the above are made from microbial cellulose produced by acetic acid bacteria. However, industrial uses other than acoustic diaphragms have been established for reasons such as high production costs, enormous energy requirements, and insufficient water resistance. The current situation is not.
[0007]
[Patent Document 1]
Japanese Patent No. 2873927 [Patent Document 2]
Japanese Patent Laid-Open No. 6-233691 [Patent Document 3]
Japanese Patent Publication No. 5-27653 [Patent Document 4]
US Pat. No. 4,588,400 [Patent Document 5]
US Pat. No. 5,086,096 [Patent Document 6]
US Pat. No. 5,290,830 [Patent Document 7]
Japanese Patent Laid-Open No. 3-165774 [Patent Document 8]
JP-A-3-157402 [Patent Document 9]
JP-A-6-313297 [Patent Document 10]
JP-A-6-250431 [Patent Document 11]
JP-A-6-287888
[Patent Document 12]
Japanese Patent Laid-Open No. 1-156600 [Patent Document 13]
JP-A-7-298777 [Patent Document 14]
JP-A-8-35155 [Patent Document 15]
JP-A-1-199604 [Patent Document 16]
Japanese Patent Laid-Open No. 10-94728 [Patent Document 17]
JP-A-5-330888 [Patent Document 18]
JP-A-6-297840 [Patent Document 19]
JP-A-5-237326 [Patent Document 20]
Japanese Patent Laid-Open No. 6-248594 [Patent Document 21]
JP-A-8-142528 [Patent Document 22]
JP-A-6-242548
[Problems to be solved by the invention]
An object of the present invention is to provide a method for dramatically increasing the specific surface area of bacterial cellulose produced by a main cellulose raw material such as pulp, cotton, and linen and microorganisms easily and at low cost, and a cellulosic material obtained by the method In addition, for example, a sheet-like material mainly composed of the cellulose-based material, which can be expected to be applied to highly functional materials utilizing advanced chemical reactivity, such as high removal of suspended particles, adsorption / filtration of organic impurities such as halogens, etc. To provide things.
[0010]
[Means for Solving the Problems]
In the industry dealing with cellulose (pulp, paper) and regenerated cellulose (fiber), the inventors of the present invention make the aqueous medium drying process at the final stage of production an essential process. We noticed that this process extremely reduced the specific surface area of the final product.
Incidentally, the specific surface area of a general pulp that has undergone a drying step of an aqueous medium is about 0.6 m ² / g, and even Avicel, which is a pulverized pulp, is about 1.2 m ² / g. Even bacterial cellulose composed of tens of nanometers of fibrils is only about 1.5 m ² / g when purified from an aqueous medium culture system and dried with hot air.
[0011]
While studying the drying process based on the above knowledge, the present inventors have a significantly large specific surface area easily and at low cost by immersing the cellulosic material in an organic solvent having a relative dielectric constant of 3 or less and drying it. It has been found that it can be obtained, and the present invention has been completed.
That is, the present invention
1. A cellulose-based fibril having a specific surface area of 55 m ² / g or more obtained by immersing a cellulose-based material produced by a microorganism in an organic solvent having a relative dielectric constant of 3 or less and drying it ;
2. 2. The cellulose fibril according to 1 above, wherein the organic solvent having a relative dielectric constant of 3 or less is at least one selected from aromatic hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons,
3. The cellulosic fibrils according to 1 or 2 above, wherein the cellulosic material produced by the microorganism is an independent body or a linked body that forms macrofibrils radially from the central region by optical microscope observation,
4). Any one of the above 1 to 3 characterized in that the cellulosic material produced by the microorganism is highly interconnected in a microporous manner with a micropore in a phase-separated structure as observed in an electron microscope. Cellulosic fibrils according to item,
5. Microorganism producing cellulosic material, Acetobacter Kishinamu subsp Gerhard black fermenter (Acetobacter xylinum subsp.sucrofermentans), Acetobacter xylinum (Acetobacter xylinum), acetic acid or the like Acetobacter Pasutsurianusu (A.pasteurianus) Fungi (Acetobacter genus), Agrobacterium genus, Rhizobium genus, Sarsina genus, Pseudomonas genus, Achromobacter genus, Alkaligenes genus, Aerobacter genus, Azotobacter genus and Zoogrea genus, Enterobacter genus or Cluvera genus and NTG ( Cellulosic fibrils according to any one of the above 1 to 4, which are various mutant strains created by mutation treatment by a known method using nitrosoguanidine),
6). The cellulosic fibril according to any one of the above 1 to 4, wherein the microorganism that produces the cellulosic material is Enterobacter or Cluvera CJF002, various mutants thereof, and subculture microorganisms,
7). A sheet-like material mainly comprising the cellulose-based fibril according to any one of 1 to 6 above .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
As the cellulosic material, plant fibers such as cotton, pulp and hemp, and regenerated fibers such as rayon and bemberg are used.
Furthermore, as the cellulose material, a microorganism-produced cellulose fine fiber material is used. Examples of the microbial-produced cellulose-based fine fiber materials include Acetobacter xylinum subsp. Sucrofermentans , Acetobacter xylinum ATCC 23768, Acetobacter xylinum ATCC 23769, and Acetobacter pasturinus ( A. pasteurianus ) ATCC 10245, Acetobacter xylinum ATCC 14851, Acetobacter xylinum ATCC 11142, Acetobacter xylinum ATCC 10821 and other acetic acid bacteria (Acetobacter genus), Agrobacterium genus, Rhizobium genus, Sarsina genus, Pseudomonas genus, Achromo Bacter genus, Alkaligenes genus, Aerobacter genus, Azotobacter genus, Zooglaea genus, Enterobacter genus or Is produced by culturing various mutant strains created by mutating them by a known method using NTG (nitrosoguanidine) and the like.
[0013]
In particular, the cellulosic microfibrillar substance belonging to the genus Enterobacter or Cluvera, for example, produced by the CJF002 strain, is an independent or conjugated body that radially forms macrofibrils from the central region, It is characterized by being connected to each other in a microporous manner and in a circular pore manner, and has significantly higher wet compressibility and slurry viscosity than cellulose microfibrillar materials produced by acetic acid bacteria. It is particularly preferably used in the present invention because it is low. Here, the term “circular pore-like” refers to pores that appear when a polymer solution acts on a poor solvent and forms a film by phase separation, and when the polymer solution concentration is lower than the critical concentration. It is not accompanied by formation.
[0014]
These cellulosic substances produced by microorganisms are subjected to high-pressure shearing such as mixers, polytrons, self-excited ultrasonic grinders, ultrasonic oscillators, various bead mills, microfluidizers, etc. after culturing, separation, sterilization, sterilization and purification processes. The dispersion can be made using a machine.
In particular, in the case of a cellulosic microfibrillar substance produced by the CJF002 strain, the dispersion operation is extremely easy and the energy consumption is small as compared with that produced by acetic acid bacteria. Here, the CJF002 strain is the patent microorganism deposit center of the Institute of Biotechnology, Institute of Industrial Science and Technology, Ministry of International Trade and Industry, which has an address of 1-3-3 Higashi 1-chome, Tsukuba City, Ibaraki, Japan, on March 29, 2000. And Enterobacter sp. Microorganism strains deposited under the designation “Enterobactersp. CJF-002” and accession number “FERMP-17799”.
[0015]
Cellulose has a specific moisture content of 2-5% and 30-40%, and changes in affinity with water (H. Ono, H. Yamada, S. Matsuda, K. Okajima, T. Kawamoto, H. Iijima, "1H-NMR relaxation of water molecules in the aqueous microcrystalline cellulose suspension systems and their viscosity", Cellulose, 5,231 (1998)), change (Chihiro Yamane of the long-period structure, Hirofumi Ono, Tomoko Hongo, Masatoshi Saito, Kunihiko Okajima, fiber Because it has the property of causing academic journals, Vol. 53, No. 8, 321 (1997)), it is better to use cellulose with a moisture content of 2% or more. In the case of pulp, cotton, hemp, etc., since it does not contain much water in nature, it can be used with excess water, but it has a property of highly embracing water like microbial cellulosic fine fiber materials. In such a case, if the moisture content is too high, it becomes a gel instead of being immersed in a low-polarity hydrophobic solvent, so the upper limit of the moisture content is about 200% to 300% with respect to the cellulose.
[0016]
In the case of pulp, cotton, hemp, etc., those having a higher specific surface area can be obtained by disaggregation, beating and shearing in the immersion liquid. The apparatus for performing the disaggregation, beating, and shear load is not particularly limited. For the disaggregation, for example, a high-speed stirring mixer such as TK homomixer (manufactured by Special Machine Co., Ltd.) can be used. It may be with or without a stator around the stirring blades. For example, beater (JIS handbook paper / pulp, edited by Japan Standards Association, 1999, P352, Annex A) can be used. For example, a Menton Gorin homogenizer or a microfluidizer can be used as the shear load.
Organic solvents with a relative dielectric constant of 3 or less, which are low polarity hydrophobic solvents, are aliphatic hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, specifically cyclohexane, toluene, carbon tetrachloride. It is.
[0017]
The specific surface area of the cellulosic material obtained by immersing in an organic solvent having a relative dielectric constant of 3 or less and drying is 10 m ² / g or more, preferably 15 m ² / g or more, more preferably 50 m ² / g or more. The upper limit of the specific surface area is not limited, but is 150 m ² / g or less due to technical difficulties.
In particular, when the cellulosic material is a cellulosic material to produce a microorganism, specific surface area is 55m ² / g or more, preferably 80 m ² / g or more, more preferably 95 m ² / g or more. The upper limit of the specific surface area is not limited, but is 200 m ² / g or less due to technical difficulties.
If a liquid obtained by immersing and dispersing a cellulosic material in an organic solvent having a relative dielectric constant of 3 or less, or adding a third component such as another fibrous material or inorganic material, and making a diluted and dispersed dispersion, A sheet-like material having a large specific surface area can be obtained.
[0018]
As the third component of the present invention, fine fibers derived from natural cellulose fibers and regenerated cellulose fibers, polyolefin fine fibers, polyester fine fibers, polyamide fine fibers, polyacrylic fine fibers, carbon fibers, glass fibers, At least one of alumina fiber, asbestos, and various inorganic whiskers may be mixed and dispersed.
If necessary, for example, calcium carbonate, clay, talc, glass fine powder, carbon powder, kaolin, calcined kaolin, delaminated kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, hydroxide Inorganic fillers such as zinc, magnesium hydroxide, calcium hydroxide, magnesium silicate, calcium silicate, calcium sulfate, aluminosilicate, silica, sericite, celite, bentonite and smectite can also be mixed and dispersed.
[0019]
Also, functional inorganic substances can be mixed and dispersed. Functional inorganic substances include: barium carbonate as an X-ray shield / ferroelectric material, zirconium oxide as a low heat conductor / high refractive index material, zinc oxide as a catalyst raw material / photoreceptor substrate, and ferromagnetic material γ-ferrite, barium titanate as ferroelectric, cobalt oxide as paramagnetic / low electrical conductor, tin oxide as catalyst / abrasive, alumina oxide, silicon oxide, titanium oxide as UV absorber / photocatalyst, etc. It can be illustrated.
The amount of the third component added is not limited, and can be determined by the engineer in terms of cost and performance in consideration of the end use.
[0020]
The third component is 90% or less, preferably 80% or less, from the viewpoint of exerting the performance of the nano-level fibrous microorganism-produced cellulose material of the present invention.
In particular, in the case of hydrophobic fiber materials and fine particle systems, the sheet form cannot be maintained unless it is 80% or less.
In addition, in the case of an electronic material substrate or a separator for a capacitor, it should be tens of percent or less in order to utilize the low thermal expansion property of microorganism-produced cellulose.
The thickness of the sheet-like material of the present invention is not limited, but the thickness of an electronic material substrate or capacitor separator that is required to be light and thin is 30 μm or less, preferably 20 μm or less.
[0021]
Other applications of the present invention include a separator for condensers, an oxygen-concentrated thin film, a super ink absorbing sheet, a HEPA filter, a precision separation / filter material, and a humidity self-adjusting material.
In the sheet-like material of the present invention, when other fine fibers and inorganic fillers are blended for the purpose of imparting functions such as strength maintenance to the microorganism-produced cellulose-based material, the sheet-like material is impregnated, The material to be coated and thermocompression-bonded should be selected with consideration given to improving the functions of fine fibers, inorganic fillers and the like that are already blended as constituent elements.
For example, a microorganism-produced cellulose sheet containing 50% polyester fine fibers is useful as a HEPA filter by itself, but if it is impregnated / crosslinked with polyglucosamines, the effect of ionically removing fine dust increases. .
[0022]
In addition, the microbial-produced cellulose sheet in which titanium oxide is finely dispersed has UV absorption and photocatalytic effects, so it is impregnated with other highly transparent materials such as PMMA, polycarbonate, PVA, coating, and thermocompression bonding. It is desirable to do.
Furthermore, it is desirable that the microbial-produced cellulose-based sheet material provided with barium carbonate as an X-ray shield / ferroelectric is impregnated, coated, and thermocompression-bonded with another material having high strength.
Similarly, the sheet-like material of the present invention is composed of zirconium oxide as a low heat transfer material / high refractive index material, zinc oxide as a catalyst raw material / photoreceptor base material, γ ferrite as a ferromagnetic material, titanium as a ferroelectric material. Barium acid, cobalt oxide as a paramagnetic / low electrical conductor, tin oxide as a catalyst / abrasive, alumina oxide, silicon oxide, and the like can be used as components.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Next, examples of the present invention will be given and described in detail.
In addition, the specific surface area after the process of a cellulosic substance was measured with nitrogen using the autosorb-1 by Cantachrome Co., Ltd. The specific surface area was calculated by the BET method.
[ Reference Example 1]
Water of 30 wt% was given to commercially available softwood pulp, and further, toluene was added to adjust the pulp concentration with respect to the total amount to 2 wt%, and shear load treatment was performed with a microfluidizer. This was directly dried with hot air, and then the specific surface area was measured.
The specific surface area of the obtained product was 15 m ² / g.
[Comparative Example 1]
Water was added to the above-mentioned softwood pulp so that the pulp concentration became 2 wt%, and the shear load treatment was performed in the same manner as described above.
The specific surface area of the obtained product was 0.6 m ² / g.
[0024]
[Example 1 ]
Preparation of microbial-produced fine fibrous cellulosic material dispersion Polysaccharide-production-medium, Akihiko Shimada, Viva Origino, 23, 1, 52-53, 1995) with 2.0% glucose After the sterilization treatment, 1000 L of that was put into a 3000 L fermenter, inoculated with CJF-002 strain to 10 ⁴ CFU / ml, and agitated with aeration at 30 ° C. for 2 days under aeration. .
(Incidentally, the form of the microorganism-produced fine fibrous cellulosic material obtained by this agitation culture with an optical microscope is shown in FIG. 1. According to this, independent bodies or macromolecules that form macrofibrils radially from the central region are shown. The cellulosic material of the body was obtained, and the scanning electron microscope observation of the cellulosic material is shown in Fig. 2, and the micropores are highly interconnected with each other in the form of a circular pore. It was confirmed that
Then, after filtering, washing and pressing with a screen mesh, immersing in 1% NaOH solution after sterilization, re-neutralizing, washing with water, and pressing the cotton-like body containing moisture by pressing and pressing (water: about 1000 wt% of cellulose) Obtained easily.
Next, after adjusting the above-mentioned water-containing cotton-like body (water: about 1000 wt% with respect to cellulose) by air-drying or acetone treatment so that the water content is about 300%, carbon tetrachloride, toluene, cyclohexane Then, after immersion and dispersion, they were dried in hot air as they were.
The specific surface areas of the obtained materials were 98, 113, and 132 m ² / g, respectively, which were about twice or more that of the freeze-drying method of Comparative Example 2 described later.
[0025]
[Comparative Example 2]
The cotton-containing body containing water (water: about 1000 wt% of cellulose) was subjected to ordinary freeze-drying, hot-air drying, so-called acetone substitution drying, and specific surface areas were measured. 1 m ² / g and the lyophilizate showed the largest specific surface area. The so-called solvent replacement method was only 1/10 of the lyophilization method.
[0026]
[Example 2 ]
Using acetic acid bacteria ATTC10245, 4% fructose as a carbon source, cellulose fine fibers were obtained with a small jar fermenter (total volume 1000 L) (based on the method described in JP-A-10-195713), and with Polytron A water-containing body having a concentration of 10% was obtained.
Next, after adjusting the above-mentioned water-containing body having a concentration of 10% ((water content: about 1000 wt% with respect to cellulose) by compressed air drying, acetone treatment or the like so that the water content becomes about 300%, carbon tetrachloride, toluene, After immersing and dispersing in cyclohexane, they were dried in hot air as they were.
The specific surface area but obtained are each a 81,95,112m ² / g, it was twice or more freeze-drying method of Comparative Example 3 to be described later.
[0027]
[Comparative Example 3]
When the specific surface area was measured by subjecting the water-containing body having a concentration of 10% (water: about 1000 wt% to cellulose) to normal freeze-drying, hot-air drying, so-called acetone substitution drying, and 45, 1.0, 4 and 4 respectively. .1m a ² / g, lyophilizate showed maximum specific surface area. so-called was only 1/10 of the freeze-drying method in the solvent displacement method.
[0028]
[Example 3 ]
1 g of microorganism-produced cellulose having a specific surface area of 132 m ² / g and 1 g of fine polyester suf (0.15 denier, length 3 mm) obtained in Example 1 were simply dispersed in 50 g of toluene, 50 g of water was added, and blender was used. After making into a semi-emulsified state, while adding stirring, the amount of toluene was gradually increased, and finally a dispersion having 500 g of toluene added thereto was obtained. Using this dispersion, paper was formed on a 200-mesh wire net under reduced pressure and dried with hot air to obtain a sheet-like material having a specific surface area of 84 m ² / g. Using this sheet, the particle removal rate was measured with an evaluation device for HEPA filters equipped with a 0.3 μm particle generator, and it showed a removal performance of 99.999%.
[0029]
【The invention's effect】
The present invention provides a cellulose having a remarkably high specific surface area, starting from bacterial cellulose produced by microorganisms and bacterial cellulose produced by microorganisms such as pulp, cotton, and hemp, and a sheet-like material mainly comprising the suspended particles. It is possible to provide highly functional materials utilizing advanced removal of organic impurities, adsorption and filtration of organic impurities such as halogens, and advanced chemical reactivity.
[Brief description of the drawings]
1 is an optical micrograph showing the shape of fibers of a microorganism-produced fine fibrous cellulosic material obtained by stirring culture (rotating stirring) in Example 1. FIG.
2 is a scanning electron micrograph showing the shape of a fiber of a microorganism-produced fine fibrous cellulosic material obtained by stirring culture (rotating stirring) in Example 1. FIG.

Claims (7)

A cellulose-based fibril having a specific surface area of 55 m ² / g or more obtained by immersing a cellulose-based material produced by a microorganism in an organic solvent having a relative dielectric constant of 3 or less and drying it.   2. The cellulose fibril according to claim 1, wherein the organic solvent having a relative dielectric constant of 3 or less is at least one selected from aromatic hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons. The cellulosic fibril according to claim 1 or 2 , wherein the cellulosic material produced by the microorganism is an independent body or a linked body that forms macrofibrils radially from the central region by optical microscope observation. The cellulosic material produced by the microorganism is highly interconnected in a micropore-like manner with a micropore and in a circular pore as called by a phase separation structure . The cellulosic fibril according to item 1 . Microbes that produce cellulosic substances are acetic acid such as Acetobacter xylinum subsp. Sucrofermentans , Acetobacter xylinum , A.pasteurianus, etc. Fungi (Acetobacter genus), Agrobacterium genus, Rhizobium genus, Sarsina genus, Pseudomonas genus, Achromobacter genus, Alkaligenes genus, Aerobacter genus, Azotobacter genus and Zoogrea genus, Enterobacter genus or Cluvera genus and NTG ( The cellulose-based fibril according to any one of claims 1 to 4 , which is a variety of mutant strains created by mutation treatment by a known method using nitrosoguanidine) or the like. The cellulosic fibril according to any one of claims 1 to 4 , wherein the microorganism that produces the cellulosic material is Enterobacter or Cluvera CJF002, various mutants thereof, and subcultured microorganisms. A sheet-like material mainly comprising the cellulose-based fibril according to any one of claims 1 to 6 .

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