JP3063396B2 - Method for producing fine fibrous cellulose - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fine fibrous cellulose, which has a high viscosity even in a low-concentration suspension and can form a suspension with high suspension stability. .

[0002]

2. Description of the Related Art Fine fibrous pulverized product of cellulose fine powder or particles has a large surface area, has a high affinity for water, has a strong power to retain water, has a high viscosity even at a low concentration, and has a high viscosity. Since a suspension having excellent stability can be formed, it is useful as an excellent humectant, dispersant and thickener.

[0003] It has been well known to produce fine particles having a large surface area by mechanically pulverizing cellulose fibers. For the coarse pulverization, a roll crusher or a coarse pulverizer is used. For example, a rotary disc mill known as a high-speed impact crusher is mainly used.

[0006] Cellulose powder or particles produced and commercially available by mechanical pulverization are prepared from fine fibers produced as a by-product from a refining process in the production of dissolved pulp, which are aggregated, dehydrated, dried, and dried. A pulp floc mainly composed of parenchyma cells obtained by pulverization and classification, and a softwood pulp obtained by mechanically pulverizing to a mean particle size of about 300 μm are known.

However, since cellulose is an organic substance and is soft, it is difficult to obtain sufficiently miniaturized cellulose particles only by mechanical pulverization treatment. Generally, a method that combines mechanical processing and mechanical processing is used.

[0006] As a method of miniaturizing cellulose fibers by a chemical treatment, the fact that the cellulose fibers are composed of a crystalline region and an amorphous region and the amorphous region is easily reactive to chemicals is used. A method is known in which an amorphous region is eluted by reacting a fiber with a mineral acid to obtain cellulose particles mainly composed of crystal parts, so-called microcrystalline cellulose. A method is also known in which the chemical treatment is lightly performed, the mechanical strength of the cellulose fiber is reduced, and then the material is pulverized mechanically, that is, a method combining chemical treatment and mechanical treatment (paper pulp technology). Times Showa 60
(See pages 5-11 of August issue).

[0007] The use of the cellulose fine powder or particles produced in this way includes a wide range of applications such as filter aids, fillers for rubber, excipients such as pharmaceutical tablets, suspension stabilizers, thickeners, shape-retaining agents and the like. And various fields are known.

However, by utilizing the effects such as thickening, dispersion stability, and gel forming properties of the cellulose fine powder or particle suspension, cellulose particles are used as a suspension stabilizer, a thickener, and a shape-retaining agent. In this case, since the affinity between the cellulose fiber and water is low, it is necessary to use this at a high concentration or a high addition rate.

In order to improve the above drawbacks, a microcrystalline cellulose having a surface coated with a water-soluble polymer, especially for food use, is known (Japanese Patent Publication No. 52-120717).
No.). However, such fine powders have high hygroscopicity, and easily rot when dispersed in water,
Alternatively, there is a problem that the viscosity is reduced by heating.

As a method of homogenizing a microcrystalline cellulose suspension, when the microcrystalline cellulose is passed through a small-diameter orifice, the suspension is added at least to 200 kg / cm.
Applying a high velocity with a pressure difference of ² and then colliding and rapidly decelerating to effect a shearing and cutting action; and repeating this step to provide a suspension in which the microcrystalline cellulose is substantially stable. It is known that the microcrystalline cellulose suspension produced by the step of forming a suspension exhibits stable dispersibility and high viscosity even at a very low solid content (Japanese Patent Application Laid-Open No. 59-120338). No.).

However, in the method using the high-pressure homogenizer, it is necessary to repeatedly apply a high pressure to the fibrous cellulose suspension to pass through a fine orifice, which causes a problem that the treatment efficiency is low and the cost is high. For this reason, there is a demand for a method capable of more efficiently producing cellulose fines that provide a stable suspension with high viscosity even at a low concentration.

[0012]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks, and to obtain cellulose fine particles from cellulose powder or particles as raw materials to give a stable suspension having a high viscosity even at a low concentration. An object of the present invention is to provide a method for efficiently producing a fibrous pulverized product.

The present inventors have found that a stable suspension having a high thickening effect even at a low concentration can be obtained by pulverizing cellulose powder or particles into fine fibers, increasing the surface area and increasing the affinity for water. Considering that a liquid may be obtained, we examined the wet grinding of cellulose fine powder or particles, and performed fine grinding of cellulose fine powder or particles efficiently by performing wet grinding using a vibration mill grinding device. As a result, it has been found that the resulting fine fibrous pulverized material has extremely excellent suspension stability, high viscosity and water holding power, and based on this, the present invention has been completed.

[0014]

The fine fibrous cellulose of the present invention is obtained by wet milling cellulose fine powder or particles into fine fibrils in a vibrating mill mill, whereby a 2% by weight suspension is prepared. Viscosity of 50 cp or more, 0.5% by weight
A fine fibrous pulverized product having a suspension stability of 50% or more and a water holding power of 150% or more is obtained.

The vibrating mill pulverizer used in the method of the present invention vibrates the pulverizing container to move the pulverizing medium (beads or balls) filled in the pulverizing container to apply a shearing force, an impact force, a frictional force, etc. to the sample. It is a device that gives and crushes. As the crusher used in the present invention, any device such as a circular oscillating mill, an oscillating oscillating mill, and a centrifugal mill can be used as long as it is a vibration mill crushing device.

As the material of the grinding medium (beads or balls), glass, alumina, zirconia, zircon, steel, titania and the like can be used. The particle size of the crushing medium may be as small as 0.5 mm in average particle size or as large as 30 mm in average particle size, but is limited by the performance of the crusher, preferably from 1 mm. 8mm
Range. Processing conditions such as the type of media, the average diameter, the number of revolutions of the pulverizer, and the processing concentration can be appropriately selected depending on the physical properties of the cellulose fine powder or particles as the pulverized sample and the required cellulose particle fine fibrous pulverized material. It is possible.

[0017] The amount of grinding media placed in the grinding vessel is between 20% and 90% of the volume of the grinding vessel. If the filling rate is low,
A so-called short path occurs in which the sample is not sufficiently ground and comes out of the grinding container. If the filling rate is increased, the pulverization efficiency is generally good, but if it is too high, there is a problem that the sample is difficult to pass, so that 40% to 80% is appropriate.

The concentration of the cellulose particle suspension during the pulverization treatment varies depending on the properties and particle size of the pulverized sample, but is at most 15% by weight, preferably 0.5% or more.
0% or less. If the concentration is higher than 10%, the viscosity may be too high at the time of pulverization, particularly for cellulose particles having a large particle size.

As the cellulose fine powder or particles to be subjected to the pulverizing step, for example, commercially available
(1) Obtained by mechanical pulverization of cellulose fiber (pulp floc (manufactured by Sanyo Kokusaku Pulp Co., Ltd.), self-locked PB (manufactured by Georgia Pacific), cellulose powder B (manufactured by Rettenmeier Brothers)
And (2) those obtained by chemical treatment of eluting the amorphous region of cellulose fibers with mineral acid (such as Avicel (manufactured by Asahi Kasei Kogyo Co., Ltd., manufactured by Merck)) and (3) light mineral acid treatment. Then, a combination of chemical treatment of pulverization using a pulverizer and mechanical pulverization (KC Floc (manufactured by Sanyo Kokusaku Pulp Co., Ltd.), Solka Floc (manufactured by James River Company), etc.), and (4) paper It is possible to use so-called fine cellulose fibers in white water that have come off from the wire of the wire part in the papermaking process, but it is not limited to the above, and any cellulose fine powder or particles can be used. It is.

The shape of the cellulose fine powder or particles is desirably spherical or rod-shaped in view of the liquid feeding operation.
The shape may be any shape such as a rod shaft shape, a short fiber shape or an irregular shape. The average particle size is desirably 500 μm or less from the viewpoint of the liquid feeding operation, and may be as small as small.

As a medium for the suspension to be treated, water is basically used, but it is chemically inert in the treatment step.
In addition, a mixed solvent with water or an organic solvent such as lower alcohol, ethylene glycol or glycerin, or water having a fluidity that can be used as a carrier for cellulose can be used.

The pulverizing method may be either a batch type or a continuous type. It is also possible to connect several pulverizers in series, to perform coarse treatment in the first stage and fine in the subsequent stage. is there.

Changes in the morphology of the cellulose particles during the pulverization process were observed with an optical microscope and a scanning electron microscope. Depending on the processing conditions and the type of raw cellulose,
The average particle size of the untreated cellulose particles is as small as 15
５０50 μm, up to 500 μm, the shape of which is spherical or rod-shape. When the cellulose particles having an average particle diameter of 33.6 μm were wet-pulverized by the vibration mill device according to the present invention, at the initial stage of pulverization, no apparent change was observed in the fiber width. 4 μm
The fine fibers of each other or the fibers and the unmilled part are mutually connected or entangled in several to several tens of parts, and when further pulverized, the fiber width becomes 0.7 μm or less It becomes crushed material.

As described above, when the cellulose fine powder or particles are wet-pulverized by a vibration mill pulverizer,
As the cellulose fine powder or particles become finer, the surface area increases and the affinity with water increases, so that the viscosity, the ability to retain water (water retention power), and the stability of the suspension increase.

The fine fibrous pulverized product of the cellulose particles obtained according to the present invention has a viscosity as an aqueous suspension,
It has completely different properties from the raw material cellulose fine powder or particles in terms of stability, water holding power, and the like, and it can be inferred from these three physical properties how much miniaturization has progressed. Therefore, the viscosity, suspension stability, and water holding power can be used as indices indicating the degree of pulverization.

The viscosity was measured by Tokyo Keiki DVL-B.
Using a mold viscosity type, the measurement was performed at a 2% by weight aqueous suspension concentration, 20 ° C., and a rotor rotation speed of 30 rpm.

The stability of the suspension was measured by diluting the fine fibrous cellulose particles with water, preparing a 0.5% by weight suspension, placing the suspension in a 500 ml graduated cylinder, and degassing under reduced pressure. After standing at 20 ° C. for 1 hour, the ratio of the volume remaining without sedimentation to the original volume was measured and defined as the suspension stability.

The water retention force was measured by attaching a G3 glass filter to a cylindrical centrifuge tube having a hole in the lower part.
The sample was dehydrated by applying a centrifugal force at 0 G for 15 minutes, the weight of the wet sample subjected to centrifugal dehydration was measured, and the sample was further dried at 105 ° C. for at least 5 hours, and the dry weight was measured. The water retention was obtained by subtracting the dry sample weight from the wet sample weight after centrifugation, dividing this by the dry sample weight, and multiplying by 100.

The sample to be subjected to the centrifugal dehydration treatment has a high water holding power of the crushed product, and if the water holding power is measured as it is, dehydration is difficult and the aqueous phase remains on the sample. 8% solids concentration by filtration etc.
It was preliminarily dehydrated to about １２12%, and was subjected to water holding power measurement.

The particle size of the fine powder or particles is measured by a SA-CP3 type centrifugal particle size analyzer manufactured by Shimadzu Corporation. The measurement sample was subjected to measurement after being degassed by ultrasonic treatment for about 30 minutes.

The untreated cellulose fine powder or particles are:
The viscosity of the 2% by weight suspension in water is almost identical to that of water, and the stability of the 0.5% by weight suspension is 5% or less, and the water retention power is 20 to 80%. The fine fibrous pulverized product obtained according to the present invention has an ability to retain a very large amount of water, and a 2% by weight suspension in water has a viscosity of 50 c
p or more, depending on the conditions, it is 2,000 cp or more, the suspension stability is extremely good, and the water holding power reaches 150% or more, and reaches 300% or more depending on the conditions.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below. Example 1 Cellulose particles (pulp floc W-4) manufactured by Sanyo Kokusaku Pulp Co., Ltd. were used as a sample, and the concentration was 6.
1300 ml of the suspension adjusted to 0% by weight was mixed with an experimental vibration mill pulverizer (manufactured by Chuo Kakoki Co., Ltd., MB-1 type, capacity 3).
400 ml), and 1600 ml of glass beads having an average particle size of 5 mm were placed in the grinding container, and the mixture was placed for 5 minutes.
The wet pulverization process was performed in a batch system by changing the processing time to 10 minutes, 30 minutes, and 60 minutes. At this time, the vibration mill was operated at an amplitude of 8 mm and a rotation speed of 1200 rpm. Further, the treatment was performed while maintaining the treatment temperature at 20 ° C. by adjusting the temperature of the circulating water for cooling the pulverizing vessel.

Table 1 shows the treatment time, the viscosity of the 2% by weight aqueous suspension of the obtained ground cellulose, the suspension stability of the 0.5% by weight aqueous suspension, the water holding power, the average particle size, The fiber width was shown by microscopic observation. The average particle size is SA-C manufactured by Shimadzu Corporation
It was measured with a P3 centrifugal particle size analyzer. As apparent from Table 1, the viscosity reached 750 cp, the suspension stability reached 98%, and the water retention power reached 224% after 10 minutes of the pulverization treatment, and the viscosity, suspension stability, and water retention increased as the treatment time increased. The power has increased further. Further, it is considered that the reason why the decrease in the average particle diameter is not small even when the treatment time is lengthened is that the miniaturization proceeds preferentially over the miniaturization of the particles.

The fiber width is about 20 to 30 μm when the pulverization time is 5 minutes, which is almost the same as that of the untreated one. However, since the water holding power is high, cracks and the like are generated in the particles, and the fine fibers are formed inside. It seems to be happening. At a crushing time of 10 minutes, the fiber width is still 20 to 30 μm, but the shape of the whole particles is broken. Furthermore, in the case of the pulverization treatment time of 30 minutes, many of the fibers were finely formed with a fiber width of 2 to 4 μm, and these fibers had a shape of several tens of fibers, some of which were bonded or entangled. At a crushing time of 60 minutes, the fiber width is 2 to 4 μm when observed with an optical microscope, but is 0.05 to 0.7 μm when observed with a scanning electron microscope.
Had become a fine fiber material.

[0035]

[Table 1]

Example 2 Cellulose particles (KC Floc 400 manufactured by Sanyo Kokusaku Pulp Co., Ltd.) obtained by weakening mechanical strength by mild mineral acid treatment and then mechanically pulverizing were used as a sample.
This was prepared as a suspension 14 prepared in water at a concentration of 6.0% by weight.
00 ml of vibration mill for experimental use (Chuo Kakoki Co., Ltd.)
, MB-1 type, capacity 3400 ml), and zirconia beads having an average particle diameter of 3 mm
1 was placed in a pulverizing container, and the wet pulverizing treatment was carried out in a batch manner by changing the treatment time to 10 minutes, 30 minutes, and 60 minutes. At this time, the vibration mill was operated at an amplitude of 8 mm and a rotation speed of 1200 rpm. In addition, the treatment was performed while maintaining the treatment temperature at 60 ° C. by adjusting the temperature of the circulating water for cooling the pulverizing vessel.

Table 2 shows the treatment time, the viscosity of the 2% by weight aqueous suspension, the suspension stability of the 0.5% by weight aqueous suspension, the water holding power,
The results of the relationship with the average particle size are shown. The average particle size was measured using a SA-CP3 centrifugal particle size analyzer manufactured by Shimadzu Corporation. Table 2
As is clear from Table 2, as the treatment time was increased, the viscosity, suspension stability, and water holding power were further increased.

[0038]

[Table 2]

Example 3 A suspension 1400 prepared by dissolving an amorphous part with a mineral acid and using water as a sample was prepared using microcrystalline cellulose (Avicel manufactured by Merck) to a concentration of 6.0% by weight with water.
ml of the experimental vibration mill (Chuo Kakoki Co., Ltd., MB-1)
(Model, capacity: 3400 ml), and 2,000 ml of glass beads having an average particle diameter of 5 mm were put into the grinding container, and wet grinding treatment was performed in a batch manner by changing the treatment time to 10 minutes, 30 minutes, and 60 minutes. The amplitude of the vibrating mill at this time is 8m
m and the number of rotations were 1200 rpm. Further, the treatment temperature is adjusted to 20 by adjusting the temperature of the circulating water for cooling the pulverizing vessel.
The treatment was performed while maintaining the temperature.

Table 3 shows the treatment time, the viscosity of the 2% by weight aqueous suspension of the obtained ground cellulose, the suspension stability of the 0.5% by weight aqueous suspension, the water holding power, and the average particle size. The relationship with the diameter was shown. The average particle size was measured using a SA-CP3 centrifugal particle size analyzer manufactured by Shimadzu Corporation. As is evident from Table 3, the viscosity, suspension stability, and water retention increased as the grinding time increased.
Compared to crushed pulp floc and KC floc,
Both the viscosity and the water holding power are slightly lower, and it takes some time to obtain high suspension stability. Further, the average particle diameter was sharply reduced to about ５ when treated for 10 minutes as compared with the untreated one, but no sharp decrease was observed even if the treatment time was prolonged thereafter.

[0041]

[Table 3]

Example 4 Bleached kraft pulp of hardwood was beaten to a freeness of 426 ml with a Niagara beater, and the pulp was sieved with a Bower Macnett sieving machine to settle and concentrate 150 mesh passes, followed by centrifugation. What was concentrated by the separator was used as a crushed sample. At this time, the number average fiber length of the sample was 80 μm. The number average fiber length was measured with an FS-200 type fiber length measurement device manufactured by KAJANI, Finland. This suspension (1300 ml), which was adjusted to a concentration of 4.0% by weight with water, was subjected to an experimental vibration mill (Chuo Kakoki Co.
, MB-1 type, capacity 3400ml), and 1600ml of glass beads with an average particle size of 5mm in a grinding container, and wet processing by batch method with changing processing time to 10 minutes, 30 minutes and 60 minutes Processed. At this time, the vibration mill was operated at an amplitude of 8 mm and a rotation speed of 1200 rpm. Further, the treatment was performed while maintaining the treatment temperature at 20 ° C. by adjusting the temperature of the circulating water for cooling the pulverizing vessel.

Table 4 shows the treatment time, the viscosity of the 2% by weight aqueous suspension of the obtained cellulose ground product, the suspension stability of the 0.5% by weight aqueous suspension, the water holding power, and the number average. The relationship with the fiber length was shown. As is clear from Table 4, the viscosity, suspension stability and water holding power were further increased as the treatment time was increased.

[0044]

[Table 4]

[0045]

According to the present invention, a fine fiber having a high water holding power, a high viscosity even at a low concentration and a high suspension stability is obtained by subjecting cellulose fine powder or particles to wet grinding by a vibrating mill grinder. It is intended to efficiently produce a pulverized product. According to the present invention, it is possible to efficiently produce fine fibrous cellulose having a 2% by weight aqueous suspension having a viscosity of 50 cp or more, a very good suspension stability, and a water retention capacity of 150% or more. Is now possible.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-117139 (JP, A) JP-A-62-127000 (JP, A) JP-A-57-77387 (JP, A) JP-A-56-77387 100801 (JP, A) JP-A-6-10286 (JP, A) JP-A-6-10288 (JP, A) JP-A-62-240302 (JP, A) JP-A-3-111426 (JP, A) JP-A-59-19197 (JP, A) JP-A-57-212231 (JP, A) JP-A-63-94948 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21D 1/00-1/38 C08J 3/12 C08L 1/00 C08L 15/08

Claims (1)

(57) [Claims] 1. The cellulose fine powder or particles are wet-pulverized by a vibrating mill pulverizer so that a 2% by weight suspension has a viscosity of 50 cp or more and a 0.5% by weight suspension has a suspension stability. A method for producing fine fibrous cellulose, characterized by obtaining a finely pulverized product having a water holding power of 50% or more and a water holding power of 150% or more.