JP6916425B2 - Manufacturing method of ultra-small cellulose - Google Patents

Description

The present invention relates to a method for producing ultra-small cellulose.

In recent years, nanotechnology has been attracting attention for the purpose of refining substances to the nanometer level and obtaining new physical properties different from the conventional properties of substances. Ultra-small cellulose produced from cellulosic raw materials by nanotechnology such as chemical treatment and crushing treatment has excellent strength, elasticity, thermal stability, etc., so it is a filter medium, filter aid, base material of ion exchanger, chromatograph. It is used in industrial applications such as fillers for chromatographic analysis equipment and fillers for blending resins and rubbers, and as blends for cosmetics such as lipsticks, powdered cosmetics, and emulsified cosmetics. In addition, since ultra-small cellulose has excellent water-based dispersibility, it is a viscosity-retaining agent for foods, cosmetics, paints, etc., a toughening agent for food raw material fabrics, a water-retaining agent, a food stabilizer, a low-calorie additive, and an emulsion stabilization agent. It is expected to be used in many applications such as chemical aids.

As a method for producing ultra-small cellulose, Patent Document 1 proposes a method in which cellulose fibers are ozone-treated in a gas phase, dispersed in water, and the obtained aqueous suspension of cellulose fibers is pulverized. It is said that by applying such ozone treatment, the fibers can be swelled together with the oxidation reaction, and the fibers can be efficiently refined by the subsequent pulverization treatment.

JP-A-2010-254726

However, the method described in Patent Document 1 requires mechanical miniaturization treatment many times in order to obtain extremely small cellulose, which imposes a heavy burden on the mechanical miniaturization treatment.

An object of the present invention is to provide a method for producing ultra-small cellulose using pulp bleached by a vapor phase reaction, which reduces the burden of mechanical miniaturization treatment.

In order to solve this problem, a pretreatment for mechanical micronization treatment was attempted. Surprisingly, when the beating treatment was performed after the enzyme treatment at a pulp concentration within a predetermined range, suitable microfibril cellulose fibers were obtained after the beating treatment. It was found that when the microfibrillose fibers were used for mechanical micronization treatment, extremely small cellulose could be produced with a small burden.

The present invention mechanically uses a step of enzymatically treating pulp bleached by a vapor phase reaction at a pulp concentration of 8 to 17% by mass, a step of beating the enzyme-treated pulp, and a microfibril cellulose fiber obtained by the beating treatment. The present invention relates to a method for producing ultra-small cellulose, which comprises a step of finely reducing the size of the cellulose.

According to the present invention, it is possible to provide a method for producing ultra-small cellulose using pulp bleached by a vapor phase reaction, which reduces the burden of mechanical miniaturization treatment.

It is a photograph of the pulp after the enzyme treatment in Example 1. It is a photograph of the microfibrillose fiber after the beating treatment in Example 1. It is a photograph of the extremely small cellulose after the mechanical miniaturization treatment in Example 4. It is a graph which shows the pseudo particle size distribution curve volume average particle diameter of the microfibril cellulose fiber.

The production method of the present embodiment includes a step of enzyme treatment, a step of beating, and a step of miniaturization (hereinafter, also referred to as "enzyme treatment step", "beating treatment", and "miniaturization treatment step"). ..

The enzyme treatment step is a step of enzymatically treating pulp bleached by a gas phase reaction.

As the pulp bleached (delignin treatment) by the vapor phase reaction, the pulp treated by ozone bleaching using ozone is exemplified as a preferable means. Although it is said that the solubility of ozone in water is several to 10 times higher than that of oxygen, it is about 1/10 of that of chlorine conventionally used for bleaching, and it can be said that it is sparingly soluble in water. Therefore, ozone bleaching has a problem that when the pulp concentration is low, the layer of water covering the cellulose is thick and the solubility of ozone in water is low, so that the reaction rate of ozone is slowed down. On the other hand, as a means for imparting strong oxidizing power, it is preferable to treat the raw material pulp at a high concentration of 25% by mass or more by a gas phase reaction in which ozone is reacted with the raw material pulp by a so-called gas phase reaction. Instead of ozone treatment, bleaching treatment by gas phase reaction using oxygen is also preferably adopted.

As the raw material pulp, various plant-derived kraft pulps and mechanical pulps are preferably used, but broad-leaved trees in which ozone treatment, which has strong oxidizing power, effectively functions even for lignin that cannot be completely removed by delignin treatment. Kraft pulp such as kraft pulp (LUKP) and coniferous kraft pulp (NUKP), especially broadleaf kraft pulp from the viewpoint of processability in the subsequent enzyme treatment process, beating process, and mechanical miniaturization process. (LUKP) is preferably used.

The ozone treatment is not particularly limited, but using a known ozone generator, the ozone concentration is 10 to 20% by mass, and the ozone addition rate is preferably 0.05 to 2 per 100 parts by mass of absolute dry pulp. The mass, more preferably 0.1 to 1 part by mass, and the treatment temperature are not particularly limited, and are appropriately adjusted in the range of 0 to 50 ° C. Since the reaction between ozone and pulp is fast and the ozone treatment time is generally within a few minutes, there is no problem with the ozone treatment time in the gas phase reaction, and the reaction temperature is the main factor. As the ozone-treated pulp, hardwood bleached kraft pulp (LBKP) obtained by ozone-treating hardwood kraft pulp (LUKP) is preferable.

Enzyme treatment is a treatment in which an enzyme cleaves the β-1,4-glucoside bond of cellulose by hydrolysis to cause depolymerization, and examples of the catalyst thereof include cellulase-based enzymes and hemicellulase-based enzymes. Enzymes are preferred.

Cellulase-based enzymes include the genus Trichoderma, the genus Acremonium, the genus Aspergillus, the genus Phanerochaete, and the genus Trametes. Cellulase system produced by the genus Humicola, Bacillus, Bacillus, Schizophyllum, Streptomyces, Pseudomonas, etc. Trichoderma cellulase-based enzymes are particularly preferable because they include enzymes, are abundant in variety, and have high productivity.

Such cellulase-based enzymes can be purchased as reagents or commercially available products, and examples thereof include CX7L (manufactured by Genecore) and FaberCare D (manufactured by Novozymes).

The pulp concentration during the enzyme treatment is 8 to 17% by mass, preferably 8 to 14% by mass, from the viewpoint of reducing the volume average particle size of the pseudo particle size distribution curve of the microfibril cellulose fibers obtained by the beating treatment described later. More preferably, 9 to 12% by mass.

In the present specification, the pseudo particle size distribution curve volume average particle diameter of the microfibril cellulose fiber conforms to ISO-13320 (2009) and is measured by a laser diffraction method using a particle size distribution measuring device. Refers to the average value MV calculated by the following formula (1) using the individual particle size di and particle volume Vi in the aqueous dispersion. Since the microfibril cellulose fiber is not in the form of particles, the particle diameter di and the particle volume Vi referred to here are values obtained by measurement assuming that the fiber is a particle.
Pseudo particle size distribution curve Volume average particle size MV = Σ (di × Vi) / ΣVi (1)

When the pulp concentration at the time of enzyme treatment is 8 to 17% by mass, the reason why the pseudo particle size distribution curve volume average particle size of the microfibril cellulose fibers obtained by the beating treatment becomes small is not clear, but the pulp concentration is 8% by mass. It is considered that the above is because the amount of the enzyme liberated in the aqueous solution is smaller than the amount adsorbed on the pulp fiber, so that the hydrolysis effect by the enzyme can be sufficiently obtained, and the pulp concentration is 17 mass. When it is less than%, it is presumed that the uniform mixing of the enzyme and the pulp fiber can be ensured, and thus the hydrolysis by the enzyme can be suppressed.

The enzyme treatment temperature is preferably 30 to 60 ° C., and more preferably 40 to 50 ° C. from the viewpoint of obtaining effective action and effect of the enzyme. The enzyme treatment temperature is the temperature of the treatment liquid, and the treatment liquid refers to a liquid including those mixed in the treatment tank for enzyme treatment. That is, it refers to a mixed solution of pulp, enzyme, water, etc. bleached by a gas phase reaction.

The method of allowing the enzyme to act on the pulp bleached by the gas phase reaction in the enzyme treatment is carried out, for example, by mixing the pulp bleached by the gas phase reaction with the enzyme solution (liquid containing the enzyme). In this case, the treatment solution is preferably an enzyme solution having an enzyme amount (FPU) of 0.1 to 300 U / ml, more preferably 1 to 200 U / ml, preferably 0.01 to 15% by mass, more preferably 0. It is preferable to mix them so as to contain 1 to 5% by mass. The protein concentration of the enzyme contained in the enzyme solution is preferably 25 to 230 mg / ml, more preferably 90 to 120 mg / ml. The present invention is not limited to the embodiment in which the enzyme solution is used, and various known embodiments can be taken.

The amount of enzyme (FPU) is defined as 1 U of the amount of enzyme that converts 1 μmol of the substrate per minute. As a measurement procedure, Whatman No. 1 Add filter and 0.05 M sodium citrate buffer (pH 4.8), add an appropriate amount of diluted enzyme solution, and mix. After reacting at 50 ° C. for 1 hour, DNS reagent is added and boiled for 5 minutes. The obtained sample is diluted and evaluated with an absorptiometer at 540 nm, and FPU / ml is calculated from the dilution rate of the enzyme that obtains 2 mg glucose.

The enzyme treatment time is preferably 1 to 6 hours, more preferably 2 to 5 hours, still more preferably 2 to 3 hours, considering the viewpoint of effectively utilizing the activity of the enzyme and the peaking due to the hydrolysis of the enzyme.

As a preferred embodiment, a step of kneading treatment (hereinafter, also referred to as “kneading treatment step”) can be further included.

The kneading treatment step is a step of kneading the pulp bleached by the vapor phase reaction before the enzyme treatment. By performing the kneading treatment, a more uniform enzyme treatment can be performed, and the volume average particle diameter of the pseudo-particle size distribution curve of the microfibril cellulose fibers obtained by the beating treatment can be reduced.

The kneading process is not particularly limited, but can be handled by kneading and defibration means by at least one selected from a kneader and a disperser.

The pulp concentration during the kneading treatment is preferably 5 to 20% by mass, more preferably 6 to 18% by mass, and even more preferably 8 to 17% by mass from the viewpoint of obtaining a sufficient kneading effect.

The beating process is a step of beating the enzyme-treated pulp.

The beating treatment is not particularly limited as long as it can obtain microfibril cellulose fibers suitable for the miniaturization treatment described later, but is a single disc refiner or a conical disc refiner as a pressurizing or atmospheric pressure refining device. , Double disc refiner, twin disc refiner, Niagara beater, and one or more selected from PFI mills.

The pulp concentration during the beating treatment is preferably 5 to 20% by mass, more preferably 6 to 18% by mass, still more preferably 8 to 17% by mass, from the viewpoint of obtaining a beating effect that causes sufficient so-called fibrillation.

In the present specification, the microfibril cellulosic fiber refers to a cellulose fiber having a Canadian standard freeness of 100 mL or less in a freshness test of pulp according to JIS P 8121 as a pre-stage for obtaining extremely small cellulose.

The pseudo-particle size distribution curve volume average particle size of the microfibrillose fiber obtained by beating treatment is not particularly limited, but from the viewpoint of reducing the burden of mechanical micronization treatment and ensuring a high recovery rate of extremely small cellulose. At most, 95 μm or less is preferable, 93 μm or less is more preferable, and 90 μm or less is further preferable.

The properties of the pulp obtained after the beating treatment are judged by the pulp viscosity, and a specific viscosity is not preferable, but at 25 ° C., 1 to 10 mPa · s is preferable, and 2 to 5 mPa · s is more preferable.

As used herein, the viscosity is measured according to JIS P 8215.

The recovery rate of the microfibril cellulose fiber is not particularly limited, but is preferably 95% or more.

In the present specification, the recovery rate of the microfibril cellulose fiber is a value calculated by the following formula (2).
100 × Mass of obtained microfibril cellulose fiber / Mass of starting material (2)

The micronization treatment step is a step for mechanically refining the microfibrillose fibers obtained by the beating treatment to obtain extremely small cellulose.

The mechanical micronization treatment is not particularly limited as long as it can obtain extremely small cellulose, but can be treated by, for example, one or more selected from a high-pressure homogenizer, a millstone type disperser, and a ball mill. can.

As used herein, microcellulose refers to one that has a single peak in the pseudo-particle size distribution curve and does not have multiple peaks. As described above, by having a single peak in the pseudo particle size distribution curve, it can be judged that the miniaturization is sufficiently progressing. The peak value of the pseudo particle size distribution curve is preferably 5 μm or more and 25 μm or less.

In the present specification, the pseudo particle size distribution curve is a curve showing a volume-based particle size distribution in an aqueous dispersion of ultra-small cellulose measured by a laser diffraction method using a particle size distribution measuring device in accordance with ISO-13320 (2009). The peak value of the pseudo particle size distribution curve indicates the most frequent diameter of the smallest cellulose. Since the extremely small cellulose is not in the form of particles, the volume-based particle size distribution and the most frequent diameter referred to here are values obtained by measurement assuming that the extremely small cellulose is particles.

If the pulp bleached by the conventional vapor phase reaction is mechanically miniaturized as it is to obtain extremely small cellulose, the burden of the mechanical miniaturization treatment is large, for example, multiple treatments are required. However, by performing the mechanical miniaturization treatment through the enzyme treatment step, the beating treatment step, and the like of the present embodiment, the number of treatments can be reduced and the burden can be reduced. More specifically, the pulp bleached by the vapor phase reaction is subjected to an enzyme treatment in advance, and the enzyme-treated pulp is beaten to a desired size and with little variation, and then mechanically refined. At times, it is possible to obtain extremely small cellulose with energy saving.

<Preparation of microfibril cellulose fibers>
Examples 1 to 3 and Comparative Examples 3 to 5 (However, Example 3 is a reference example)
Commercially available hardwood bleached kraft pulp (LBKP) using ozone treatment is used as the bleaching means, and this bleached pulp is used in a kneader defibrator (manufactured by Yamamoto Hyakuma Seisakusho, model SUS-T type) at a pulp concentration of 20% by mass. The kneading process was performed once. 18 U / ml of cellulase-based enzyme solution (manufactured by Genecore, product name CX7L) and fresh water were mixed with 2,500 g (80% by mass of water) of the kneaded pulp in the proportions shown in Table 1, and 25 After stirring at ° C., the enzyme was treated with an enzyme in a water bath at a water temperature of 50 ° C. for 5 hours (for example, the amount added in Example 1 was 50 g of a cellulase-based enzyme solution and 2,450 g of fresh water). The enzyme-treated pulp was adjusted to a pulp concentration of 10% by mass, and 300 g of the adjusted pulp was beaten once at 9600 rpm with a PFI mill (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain microfibril cellulose fibers. Obtained. As a representative example, a photograph of the pulp after the enzyme treatment in Example 1 is shown in FIG. 1, and a photograph of the microfibril cellulose fiber after the beating treatment is shown in FIG.

Example 4 (However, Example 4 is a reference example)
It was prepared in the same manner as in Example 1 except that the kneading treatment was not performed.

Comparative Example 1
It was prepared in the same manner as in Example 1 except that the kneading treatment and the enzyme treatment were not performed.

Comparative Example 2
It was prepared in the same manner as in Example 1 except that the beating treatment was not performed.

<Preparation of extremely small cellulose>
Example 4, Comparative Example 4
The microfibrillose fibers obtained by the above preparation were miniaturized using a stone mill type disperser (“Super Mascoroider” manufactured by Masuyuki Sangyo Co., Ltd.) to obtain extremely small cellulose fibers. A photograph of the extremely small cellulose after the mechanical miniaturization treatment in Example 4 is shown in FIG.

<Pseudo particle size distribution curve Volume average particle size>
After beating of each example and comparative example by laser diffraction method using a particle size distribution measuring device (“Laser diffraction / scattering type particle size distribution measuring device” manufactured by Seishin Enterprise Co., Ltd.) in accordance with ISO-13320 (2009). The individual particle size di and particle volume Vi in the aqueous dispersion of microfibril cellulose fibers were measured, and the pseudo particle size distribution curve volume average particle size was calculated by the above formula (1). The results are shown in Table 1. Further, FIG. 4 shows the pulp concentration at the time of enzyme treatment in Examples 1 to 3 and Comparative Examples 3 to 5, and the volume average particle diameter of the pseudo particle size distribution curve of the microfibril cellulose fibers obtained by the subsequent beating treatment. The graph is shown.

<Pulp viscosity>
The pulp viscosities of the microfibril cellulose fibers of each example and comparative example were measured according to JIS P 8215. The results are shown in Table 1.

<Recovery rate>
For the microfibril cellulose fibers of each Example and Comparative Example, the recovery rate of the microfibril cellulose fibers was calculated by the above formula (2). The results are shown in Table 1.

<Peak of pseudo particle size distribution curve>
Miniaturization processing of Example 4 and Comparative Example 4 by laser diffraction method using a particle size distribution measuring device (“Laser diffraction / scattering type particle size distribution measuring device” manufactured by Seishin Enterprise Co., Ltd.) in accordance with ISO-13320 (2009). After that, the volume-based particle size distribution in the aqueous dispersion of the extremely small cellulose fibers was measured, and the number of peaks and the peak value of the pseudo particle size distribution curve were examined. Here, the peak value corresponds to the mode of the pseudo particle size distribution curve described above. The results are shown in Table 2.

From the comparison between Example 4 and Comparative Example 4, the smaller the volume average particle diameter of the pseudo-particle size distribution curve of the microfibril cellulose fiber, the smaller the number of times of the miniaturization treatment, and the less the burden of the miniaturization treatment. You can see that. In Comparative Example 4, it can be seen that when the number of treatments is one, the number of peaks in the pseudo-particle size distribution curve is not single, and the desired minimum cellulose is not obtained.

From the comparison between Example 4 and Comparative Example 1, it can be seen that the pseudo-particle size distribution curve volume average particle diameter of the microfibrillose cellulose fibers becomes smaller when the enzyme treatment is performed. Further, from the comparison between Examples 1 to 3 and Comparative Examples 3, 4, and 5, when the pulp concentration at the time of enzyme treatment is 8 to 17% by mass, the volume average particle diameter of the pseudo particle size distribution curve of the microfibril cellulose fiber becomes small. You can see that.

From the comparison between Example 1 and Comparative Example 2, it can be seen that the volume average particle diameter of the pseudo-particle size distribution curve of the microfibril cellulose fibers becomes smaller when the beating treatment is performed.

The present invention is not limited to the above embodiments and examples. Various embodiments can be taken without departing from the gist of the present invention.

The ultra-small cellulose obtained by the method of the present invention can be used for industrial purposes such as a filter medium, a filter aid, a base material for an ion exchanger, a filler for a chromatography analysis instrument, a filler for blending resin and rubber, and the like. It is useful as a compounding agent for cosmetics such as lipsticks, powdered cosmetics, and emulsified cosmetics.

Claims (6)

A step of enzymatically treating pulp bleached by a vapor phase reaction at a pulp concentration of 9 to 15% by mass, a step of beating the enzyme-treated pulp, and mechanically refining the microfibril cellulose fibers obtained by the beating treatment. A method for producing ultra-small cellulose, which comprises a step of kneading the pulp bleached by a vapor phase reaction before the enzyme treatment . The enzyme treatment is carried out under the condition that the temperature of the treatment liquid is 30 to 60 ° C. and the treatment liquid contains 0.01 to 15% by mass of a cellulase-based enzyme solution having an enzyme amount (FPU) of 0.1 to 300 U / ml. The manufacturing method according to claim 1. The manufacturing method according to claim 1 or 2, wherein the beating process is a process by one or more selected from a single disc refiner, a conical disc refiner, a double disc refiner, a twin disc refiner, a Niagara beater, and a PFI mill. The production method according to any one of claims 1 to 3, wherein the miniaturization treatment is a treatment by one or more selected from a high-pressure homogenizer, a stone mill type disperser, and a ball mill. The production method according to any one of claims 1 to 4, wherein the kneading treatment is a kneading and defibration treatment by at least one selected from a kneader and a disperser. The production method according to any one of claims 1 to 5 , wherein the pseudo-particle size distribution curve volume average particle diameter of the microfibril cellulose fiber is 20 to 95 μm.

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