JPH09157304A - Manufacture of acetylcellulose with high degree of polymerization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molded article having a high degree of polymerization and resultantly a superior mechanical strength by using a bacterial cellulose as a cellulose material in an acetylation reaction wherein the cellulose is first dipped in acetic acid and then an acetylating agent consisting of acetic anhydride, methylene chloride and a small amount of sulfuric acid is made to act on the mixture. SOLUTION: A cellulose with a high degree of polymerization is produced by a cellulose-producing bacterium (stipulation no.: FERM P-14982). For example, an aerated stirred culture yields a cellulose with a weight-average polymerization degree (in terms of polystyrene) of not less than 1.6×10<4> and a stationary culture yields a cellulose with a weight-average polymerization degree of not less than 2.0×10<4> . In the acetic acid dipping process, 1 pt.wt. cellulose is dipped in 3-20 pts.wt. acetic acid and separated from acetic acid by means of a centrifuge and the like. 30-200 pts.wt. acetic anhydride, 40-200 pts.wt. methylene chloride and 0.1-10 pts.wt. conc. sulfuric acid are added to 10 pts.wt. cellulose and the mixture is kept at 20-50 deg.C for 0.5-7hrs and subsequently cast in a large amount of water.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing acetyl cellulose having a high degree of polymerization, and more particularly to a method for producing acetyl cellulose by acetylation of cellulose with sulfuric acid as a catalyst using methylene chloride as a solvent with acetic anhydride. Regarding improvement.

[0002]

2. Description of the Related Art The industrial synthesis method of acetyl cellulose is
It is roughly classified into an acetic acid method and a methylene chloride method depending on the solvent of the synthetic reaction (Jikakyo monthly report, October 1988, p.25-3).
2). As is well known, acetyl cellulose is a molding material such as fibers and films, a filter for cigarettes, various composite separation membranes (hemodialysis membranes, ultrafiltration membranes, reverse osmosis membranes, etc.), building materials such as sound absorbing materials, and paints. , And so on.

However, there is a great expectation that the properties and performance of cellulose for these applications will be further improved by increasing the mechanical strength.

[0004]

Under the background of the prior art described in the preceding paragraph, an object of the present invention is to provide an acetyl cellulose having a high degree of polymerization, and to provide a molded product of acetyl cellulose excellent in mechanical strength. To provide.

[0005]

Means for Solving the Problems As a result of earnest research to achieve the object described in the preceding paragraph, the present inventors have found that in the conventional method of acetylating cellulose by the so-called methylene chloride method,
It was found that the above object can be achieved by adopting bacterial cellulose as cellulose, and the present invention has been completed based on such knowledge.

That is, according to the present invention, cellulose is acetylated by subjecting it to an acetic acid dipping treatment and then applying an acetylating agent consisting of acetic anhydride, methylene chloride and a small amount of concentrated sulfuric acid to the cellulose to acetylate it. The present invention relates to a method for producing acetyl cellulose having a high degree of polymerization, which employs bacterial cellulose.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

As cellulose, plant cellulose obtained from cotton linter, wood pulp and the like and bacterial cellulose produced by microorganisms belonging to the genus Acetobacter and the like are known, and a high degree of polymerization acetyl cellulose which is the objective substance of the present invention. Bacterial cellulose is particularly used as a raw material for the production of. The bacterial cellulose mentioned here includes regenerated bacterial cellulose and bacterial cellulose having a functional group partially introduced therein.

As the cellulose used as a raw material for producing acetyl cellulose in the present invention, one having a polymerization degree as high as possible, for example, a cellulose derived from ascidian, valonia or the like is used, and the resulting acetyl cellulose has a high polymerization degree. Therefore, it is preferable. Further, among the bacterial cellulose of the present invention, the higher degree of polymerization of bacterial cellulose is
It is a suitable raw material for producing acetyl cellulose.

The high degree of polymerization of bacterial cellulose can be produced by a cellulose producing strain capable of producing the high degree of polymerization of bacterial cellulose.

Among the cellulose-producing bacteria, bacterial culture having a high degree of polymerization, which has a polystyrene-equivalent weight average degree of polymerization of 1.6 × 10 ⁴ or more, preferably 1.7 × 10 ⁴ or more, is obtained by agitating and culturing. Do you manufacture
Alternatively, a strain that produces a highly-polymerized bacterial cellulose having a polystyrene-equivalent weight average degree of polymerization of 2.0 × 10 ⁴ or more by static culture is preferable.

BPR3001A, among bacteria producing high degree of polymerization which can be used in the present invention, was deposited at the Patent Microorganism Depositary Center, Institute of Biotechnology, Institute of Biotechnology, Ministry of International Trade and Industry, on June 12, 1995. And is assigned the accession number FERM P-14982.

The weight average degree of polymerization of various types of cellulose such as baklaria cellulose in the present invention is RI as a detector.
Built-in GPC system (Tosoh HLC-80
20) is used and measured as follows.

Various cellulose samples were treated with a fuming nitric acid-phosphorus pentoxide solution by W.I. J. Alexander, R.A. L. Mit
cell, Analytical chemistr
It is nitrated by the method of y21, 12, 1497-1500 (1949).

As a control, simultaneously used nitrated cotton linter is used.

The cellulose nitrate was dissolved in THF (Wako Pure Chemical Grade 1) at a concentration of 0.05% and then 1.0 μm.
Filter through a pore size filter.

THF is also used as an eluent for GPC.

The flow rate is 0.5 ml / min and the pressure is 10 to 10.
13 kg f / cm ² , and the sample injection amount is 100 μl.

The column is TSKgel GMH-HR
(S) (7.5 ID x 300 mm x 2) and guard column (HHR (S)) (Tosoh Co., Ltd.)
At 35 ° C.

To calculate the molecular weight, standard polystyrene (Tosoh) is used to calculate the relative molecular weight in terms of polystyrene.

Polystyrene having a molecular weight of 2 × 10 ⁷ to 2630 was used, and the logarithm of the elution time (t) and the molecular weight (log
For M), a cubic expression: (logM = At ³ + Bt ² +
Ct + D) is approximated to create a standard curve.

As for the molecular weight, the weight average molecular weight is calculated by a program installed in the Tosoh data processing dedicated machine (SC-8020).

From these molecular weight values, the weight average polymerization degree is calculated in consideration of the degree of substitution after nitration.

As is well known, the acetic acid dipping treatment of cellulose, which is a pretreatment for the acetylation of cellulose, is performed for the purpose of swelling the raw material to enhance the permeation of the reaction reagent, and usually per 1 part by weight of cellulose. 3 to 20
Add part by weight of acetic acid and dip. The immersion treatment in the method of the present invention can also be carried out according to this.

Regarding the form of the bacterial cellulose which is the object of the immersion treatment, the bacterial cellulose produced in the fermentation liquor is separated and purified, and the dried product is subjected to the immersion treatment.

After completion of the dipping treatment, the dipping liquid is appropriately adopted from bacterial cellulose to such an extent that it remains swollen and is not dried, for example, centrifugal separation, (suction) filtration, and concentration. Acetic acid is removed.

The bacterial cellulose from which the immersion liquid has been removed in this way is acetylated by acting on it an acetylating agent consisting of acetic anhydride, methylene chloride and a small amount of concentrated sulfuric acid. Specifically, the composition of these is as follows: Acetic anhydride 30 to 200 parts by weight, methylene chloride 40 to 200 parts by weight, and concentrated sulfuric acid 0.1 to 10 per 10 parts by weight of cellulose.
Parts by weight are suitable.

The mixture of bacterial cellulose and acetylating agent can be prepared according to a conventional method, for example, 0.5 to 20 at 50 to 50 ° C.
The acetylation reaction is carried out by holding it for 7 hours. The termination of the reaction can be carried out according to the conventional method, that is, for example, the acetylation reaction mixture is poured into a large amount of water to stop the reaction.

There is no particular limitation in separating and obtaining the desired acetyl cellulose from the reaction mixture in which the reaction has been stopped, and the conventional method can be applied. That is, for example,
The target acetyl cellulose is collected by appropriately adopting a general solid-liquid separation method such as suction filtration described above.

The acetyl bacterial cellulose thus obtained can be put into distribution as its product.

The technique for producing acetyl cellulose having a high degree of polymerization described in the present invention can be applied to the preparation of various cellulose derivatives, and a cellulose derivative having a high degree of polymerization can be obtained.

Examples of cellulose derivatives include various cellulose ethers, cellulose esters, unsaturated celluloses, anhydrous celluloses, deoxycelluloses, oxidized celluloses, alkali celluloses, cellophane, viscose rayon, cellulose graft copolymers, and bioactive cellulose derivatives. And the following derivatives. Cellulose sulfate, cellulose phosphate, propionate, butyrate, valerate, caproate, heptylate,
Caprylate, laurit, myristate, palmitate, cellulose acetate butyrate, cellulose acetate propionate, acetate / methacrylate,
Acetate / malate, propionate / crotonate, acetate / N, N-diethylaminoacetate,
Propionate / morpholinobutyrate, mixed ester with unsaturated carboxylic acid, aminodeoxycellulose, sodium carboxymethylcellulose, carboxymethylhydroxyethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyalkylmethylcellulose, ethylcellulose, ethylhydroxyethylcellulose, cyanoethylcellulose, Ethyl hydroxyethyl cellulose, hydroxypropyl methyl cellulose, diethylaminoethyl cellulose, hydroxypropyl / methyl cellulose phthalate, hydroxyethyl hydroxypropyl cellulose, cellulose carbamate, aminodeoxy cellulose, halodeoxy cellulose, cationic cellulose ether Carboxylic acid-containing oxidized cellulose,
Carboxyl group-containing oxidized cellulose, 2,4-dichloro-6- (3 ', 6', 8'-trisulfo-1'-naphthylamino) -cintriazine-containing polyacrylic acid graft cellulose, ethylferrocene cellulose, chlorononyl acrylate-containing Cellulose derivative, β-galactosidase-immobilized p-aminocarbanilate cellulose, tetracycline-bonded cellulose diazobenzoate,
2,2'-methylenebis (3,4,6-trichlorophenol) 2Na salt-containing derivative, morpholine / cellulose ether complex, ethanolamine-cellulose derivative,
Phosphorus cellulose, β-amylose-immobilized cellulose derivative, and other cellulose derivatives (CMC “Development of Functional Cellulose” p.50-111)
(Described in (1985)).

[0033]

The present invention will be further described with reference to the following examples.

Example 1 (Preparation of Bacterial Cellulose by Static Culture of High Polymerization Cellulose-Producing Bacteria) BPR3001A was used as a medium 10 from glycerol stock.
Inoculation was carried out at a concentration of 1% in a 750 ml roux flask charged with 0 ml, and the mixture was allowed to stand still at 28 ° C. for 3 days. After the culture, shake the roux flask well to remove the cells from the cellulose membrane, and then add 3 ml of the bacterial solution to CSL (corn steep liquor) -F.
The cells were inoculated into a petri dish (diameter 90 mm) containing 27 ml of ru (fructose) medium, and cultured at 28 ° C. for 10 days.

After completion of the culture, the obtained cellulose membrane was washed with running water and then heated in about 500 ml of water at 80 ° C. for 20 minutes. After the heating, the cellulose membrane was further washed with running water, and then washed in about 500 ml of 0.1 N NaOH at 80 ° C.
The cells contained in the cellulose membrane were lysed by heating for 0 minutes. After lysis, add about 500 ml of cellulose membrane.
By heating at 80 ° C. for 20 minutes in distilled water. The same washing was performed 3 to 5 times while replacing distilled water to obtain purified bacterial cellulose.

The weight average degree of polymerization of this purified bacterial cellulose was 22,500 as measured by the method described above.

Example 2 (Preparation of Bacterial Cellulose by Aerated Stirring Culture of High Polymerization Cellulose-Producing Bacteria) BPR3001A was prepared from CSL-containing glycerol stock.
1% of the cells were inoculated into a 750 ml roux flask charged with 100 ml of Fru medium, and statically cultured at 28 ° C. for 3 days. After culturing, shake the Roux flask well to remove the cells from the cellulose membrane, inoculate 12.5 ml of the bacterial solution into a 500 ml flask containing 112.5 ml of medium, and 180 rpm at 28 ° C.
The cells were cultured for 3 days under the condition of m. The culture was aseptically disaggregated with a blender and 60 ml of it was added to 540 ml of CSL-
Inoculate into 11 jars containing Fru medium and adjust the pH to NH
_The main culture was carried out while controlling to 4.9 to 5.1 with ₃ gases and 1N H ₂ SO ₄ and automatically controlling the number of revolutions so that the dissolved oxygen content (DO) was 3.0% or more. went.

After completion of the culture, the obtained culture solution was diluted about 5 times with an acetate buffer and then centrifuged to recover the precipitate. After diluting the precipitate with distilled water to about 8 times the initial culture volume,
After heating at 80 ° C. for 20 minutes, the precipitate was collected by centrifugation after heating. The sediment is also occupied by 8 times the amount of 0.1 N NaO.
H, and lysed by heating at 80 ° C. for 20 minutes. After lysis, the precipitate was recovered by centrifugation. After this,
Further, the precipitate was suspended in 8 times the volume of distilled water, heated at 80 ° C. for 20 minutes, heated, centrifuged, and the precipitate was collected to wash the cellulose. The same washing was performed three times to obtain purified bacterial cellulose.

The weight average degree of polymerization of this purified bacterial cellulose was measured by the method described above, and it was 17400.

Incidentally, the CSL-Fru used in the above examples.
Is as shown in Table 1 below.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

Example 3 The purified bacterial cellulose obtained in Example 2 was subjected to solvent substitution with organic solvents such as methanol, acetone and hexane in this order and dried (JP-A-6-233691 and U.S. Pat.
Geyer, Int. J. Biol. Macromo
l. , 16, 6 (1994)).

The bacterial cellulose dried by solvent substitution was added with 20 times (weight) amount of glacial acetic acid to obtain 24
After the dipping treatment was carried out by slowly stirring with a stirrer for an hour, the acetic acid attached was removed by suction filtration.

100 parts by weight of pretreated bacterial cellulose from which acetic acid had been removed was mixed with 20 parts by weight (weight) of acetic anhydride, 20 parts by weight of methylene chloride and 1 part by weight of concentrated sulfuric acid (acetylating agent). In addition to low temperature (20 ~
When kept at 30 ° C.) for 0.5 hour, the cellulose was completely dissolved and the reaction liquid became transparent, so this time was taken as the end of the reaction.

The reaction mixture was poured into a large amount of water to stop the reaction, and acetyl cellulose was obtained. This was neutralized, washed thoroughly with water, and dried. After drying, this was dissolved in acetone, the solution was placed in a flat-bottomed glass container and air-dried, and the acetylcellulose membrane formed on the bottom surface was collected.

Comparative Example 1 An acetyl cellulose membrane was recovered in exactly the same manner as in Example 1 except that a commercially available cotton linter was used instead of the bacterial cellulose dried by solvent replacement.

Comparative Example 2 (Comparison with the acetic acid method) (a) The bacterial cellulose obtained by solvent substitution and dried in the same manner as in Example 3 was immersed in 20 times (weight) amount of glacial acetic acid for 3 hours. After treatment, suction acetic acid was removed by suction filtration.

100 parts by weight of the pretreated bacterial cellulose from which acetic acid had been removed was mixed with 20 parts by weight (weight) of acetic anhydride, 20 parts by weight of glacial acetic acid and 15 parts by weight of concentrated sulfuric acid (acetylating agent). In addition to low temperature (20-30
When kept at (° C) for 5 hours, the cellulose was completely dissolved and the reaction liquid became transparent.

Water (3 times as much as the weight of bacterial cellulose) was added, and the mixture was aged at 25 ° C. for 2 days, and then the reaction mixture was poured into a large amount of water to stop the reaction to obtain acetyl cellulose. This was thoroughly washed with water, neutralized and dried. After drying,
This was dissolved in acetone, the solution was placed in a flat-bottomed glass container and air-dried, and the acetyl cellulose membrane formed on the bottom surface was collected.

(B) A commercially available cotton linter is used in place of the bacterial cellulose dried by solvent substitution,
An acetyl cellulose membrane was recovered in exactly the same manner as in (a) above except that the acetylation reaction time was 3 hours.

Inspection Example 1 (Inspection of degree of polymerization of various acetylcellulose membranes) The weight average degree of polymerization (DPw) of the cellulose membranes obtained in Examples and Comparative Examples was examined.

In this inspection example, DPw is measured as follows. That is, a GPC (size exclusion chromatography) system "Tosoh HLC-8020" having a built-in RI (differential refractometer) as a detector is used to perform the measurement as follows.

Acetylcellulose is 0.05% in THF (tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd., reagent first grade).
After dissolving at a concentration, it is filtered with a filter having a pore size of 1.0 μm. THF is also used as the eluent for GPC. Flow rate is 0.5 ml / min, pressure is 10 to 13 kgf / c
m ² , and sample injection volume is 100 μl. The column is "TSKgel GMH-HR (S)" (7.5I).
D x 300 mm x 2) and guard column "HHR
(S) ”(Tosoh Co ,, Ltd.)
Measure at 5 ° C.

The standard polystyrene "Tosoh" is used for the calculation of the molecular weight, and the relative molecular weight in terms of polystyrene is determined. More specifically, polystyrene having a molecular weight (M) of 2 × 10 ⁷ to 2630 is used, and the elution time (t) and the logarithm of the molecular weight (log M) are expressed by a cubic expression: (log
M = At ³ + Bt ² + Ct + D) to make a standard curve. Regarding the molecular weight, the weight average molecular weight is calculated by a program installed in the Tosoh data processing computer "SC-8020".

From these molecular weight values, the weight average degree of polymerization (hereinafter abbreviated as DPw or degree of polymerization) is calculated in consideration of the degree of substitution after acetylation.

The degree of substitution was determined from the ratio of the peak intensities of the acetyl group and the hydroxyl group in the FT-IR analysis using commercially available acetyl cellulose as a reference substance. FT-IR is "FTS
165 "(manufactured by Bio-Rad) was used for the measurement by the permeation method.

The inspection results are shown in Table 2 below.

[0060]

[Table 4]

From Table 2, it can be seen that the acetyl cellulose of the present invention (obtained in Example 3) has a higher degree of polymerization (DP) than the conventional acetyl cellulose (comparative example).
w) is high. This means that when the acetylcellulose of the present invention is used in various composite separation membranes, the membrane thickness can be reduced, and the substance permeability can be remarkably improved.
The substitution degree of the acetyl cellulose obtained in the present invention was 2.4 in all cases.

In addition to the advantages of the product, the present invention requires a short reaction time in the method itself, and since methylene chloride works as a refrigerant unlike the acetic acid method, the cooling water for the reaction is reduced. There are merits such as unnecessary.

[0063]

Industrial Applicability According to the present invention, acetyl cellulose having a high degree of polymerization (DPw) can be provided, which in turn can easily provide a molded product of acetyl cellulose having excellent mechanical strength.

[0064]

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[Procedure amendment]

[Submission date] December 20, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

The acetyl cellulose thus obtained can be put into distribution as its product.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Watanabe Otohiko 32-1 Sakado, Takatsu-ku, Kawasaki City, Kanagawa KSP R & D Business Park Building B-1015 Biopolymer Research Co., Ltd. (72) Inventor Yasunori Morinaga KSP R & D Business Park Building B-1015, 3-2-1 Sakado, Takatsu-ku, Kawasaki City, Kanagawa Prefecture (72) Inventor Fumitaka Horii 4-1-1 Oridai, Uji City, Kyoto Prefecture 101

Claims (3)

[Claims] 1. After subjecting cellulose to an acetic acid immersion treatment,
A process for producing acetyl cellulose having a high degree of polymerization, characterized in that bacterial cellulose is employed as the cellulose in the method of acetylating the cellulose by acting an acetylating agent consisting of acetic anhydride, methylene chloride and a small amount of sulfuric acid on this. 2. A weight average degree of polymerization in terms of polystyrene of bacterial cellulose obtained by aeration and stirring culture is 1.6.
The method for producing a high polymerization degree acetyl cellulose according to claim 1, which is bacterial cellulose having a density of × 10 ⁴ or more. 3. A bacterial cellulose obtained by static culture, having a polystyrene-equivalent weight average degree of polymerization of 2.0 × 1.
The method for producing a high-polymerization degree acetyl cellulose according to claim 1, which is a bacterial cellulose of 0 ⁴ or more.