JPH06212587A - Production of fine fibrous cellulose - Google Patents

Abstract

PURPOSE:To rapidly obtain fine fibrous cellulose high in water-holding force by grinding fibrous cellulose with a medium stirring type wet grinding machine under a specific condition. CONSTITUTION:Fibrous cellulose is ground with a medium stirring type grinding machine into fine fibrous cellulose having a water-holding force of 210% substantially without causing a chemical change. As the fibrous cellulose is finely ground, the viscosity of the fine fibrous cellulose is increased and further its water-holding force is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for making cellulose fibers into fine fibers.

[0002]

2. Description of the Related Art It has been well known that a cellulose fiber is crushed to produce a fiber having fine particles having a large surface area. The crushing method is a high-speed method such as a rotary mill or a jet mill. The impact crushing method and the roll crusher method are mainly used. However, since cellulose is an organic substance and is soft, it is difficult to obtain fine cellulose particles only by mechanical pulverization treatment. In order to obtain fine cellulose fibers, a method combining chemical treatment and mechanical pulverization is generally used. Is used for.

As a method of combining chemical treatment and mechanical grinding, cellulose is composed of a crystalline region and an amorphous region, and since the amorphous region is easily reactive to chemicals, for example, mineral acid and A method is known in which a non-crystalline region is eluted by a reaction to obtain a cellulose fiber mainly containing a crystalline part. Then, this is further mechanically processed to obtain fine cellulose particles. Specifically, the bleached pulp is slightly acid hydrolyzed, filtered, washed with water,
It is known that a method for producing cellulose fine particles containing a partially non-crystalline region by drying and pulverizing, or a method in which refined pulp is hydrolyzed with hydrochloric acid or sulfuric acid and finely divided to leave only the crystalline region. (Paper Pulp Technology Times August 1985 Issue 5
(See page 11).

A method for producing fibrous cellulose having a fine fiber width is to pass a suspension of fibrous cellulose through a small-diameter orifice, and add at least 3000 psi to the suspension.
A high speed by a pressure difference of, and then a step of causing a cutting action by colliding this and rapidly decelerating, and a suspension in which the suspension of the cellulose is substantially stable by repeating the above steps. And a step of converting the cellulose into microfibrous cellulose without causing a substantial chemical change in the starting material of the cellulose, that is, a high-pressure homogenizer (high-pressure homogenizer). Is known (see Japanese Patent Publication No. 60-19921 and Japanese Patent Publication No. 63-44763).

[0005]

The problem to be solved by the present invention is that the method using the above-mentioned high-pressure homogenizing apparatus has a low treatment efficiency because it is necessary to apply a high pressure to the fibrous cellulose suspension and pass it through a narrow orifice. There was a problem,
The present invention is to provide a method for producing fine fibrous cellulose having improved treatment efficiency and high productivity.

[0006]

Means for Solving the Problems The means of the present invention for solving the above problems is to treat a suspension of fibrous cellulose with a media agitation type wet pulverizing device to obtain a fine fibrous cellulose having a water retention capacity of 210% or more. It is characterized by being manufactured.

The present inventors have studied the action mechanism (defibration action) of micronization of fibrous cellulose by a high-pressure homogenizer, paying particular attention to shear action, cutting action, and friction action. It has been found that as a method of efficiently miniaturizing by a shearing force generated by the difference in speed, pulverization treatment with a media agitation type wet pulverizer may be performed.

The media agitation type wet pulverization device is a device for agitating the media and fibrous cellulose filled in the pulverization container by rotating the agitator inserted in a fixed pulverization container at a high speed to generate shear stress and pulverize the media. There are a tower type, a tank type, a flow pipe type, a manual type and the like, but any device can be used as long as it is a media stirring type. Among them, sand grinder, ultra visco mill, dyno mill,
Diamond fine mill is good.

The types of media include glass beads,
Alumina beads, zirconia beads, zircon beads,
Steel beads, titania beads, etc. can be used, and the particle size can be used from fine particles having an average particle size of 0.1 mm to large particles having an average particle size of 6 mm. The processing conditions such as the type of the media, the average diameter, the rotation speed of the crusher, and the processing concentration can be appropriately selected depending on the required physical properties of the fine fibrous cellulose. Further, as a treatment method, either a batch method or a continuous method may be used, and it is also possible to connect several devices in series to perform rough treatment in the first stage and fine treatment in the latter stage. .

An example of using a hardwood bleached kraft pulp as the fibrous cellulose shows changes in the fiber morphology. When the untreated pulp and the fibrous cellulose product according to the present invention are observed with an optical microscope or an electron microscope, the untreated pulp is shown. Has a fiber width of 20 to 30 μm, a weight-loading average fiber length of about 0.8 mm, a smooth and flat cylindrical shape, and is further twisted and bent.

The pulp treated by the media agitation type wet pulverizing apparatus according to the present invention has a fiber width of 3 to 5 μ and a number average fiber length of 0.55 mm or less in the initial stage of the treatment, and has a so-called lumen. The fiber structure is being destroyed. Furthermore, when the media agitation type wet pulverization process is performed, the fiber width is 0.15μ or less and the number average fiber length is 0.25 mm.
The following are very fine fiber components.

The fine fibrous cellulosic product according to the invention has properties which are quite different from the usual pulp fibers. When the treatment is carried out by the wet agitation method using media agitation, as the fibrous cellulose becomes finer, the viscosity increases, the affinity with water increases, and the ability to retain water (water retaining power) increases.

The water retention capacity was measured by attaching a G3 glass filter to a cylindrical centrifuge tube having a hole in the lower part, and measuring 300
After dehydration treatment by centrifugation at 0 G for 15 minutes, the treated sample is taken out and the weight of the cellulose sample is measured.
The sample was then dried at 105 ° C. for at least 5 hours and the dry weight of the sample was measured. Water retention is
It is a value obtained by subtracting the dry sample weight from the wet sample weight after centrifugation, dividing this by the dry sample weight, and multiplying this by 100.

However, for the sample to be centrifuged,
Since the water retention of the pulverized product is high, if the water retention is measured as it is, dehydration becomes difficult and the water phase remains on the upper part of the sample. It was made to be 800% and subjected to water retention measurement.

The obtained fine fibrous cellulose has the ability to retain a considerable amount of water, and has a water retention capacity of 210%.
As mentioned above, depending on the conditions, it reaches 300% or more.

Comparing the water-holding powers in the beating of ordinary pulp, softwood bleached kraft pulp (710 ml of untreated freeness, 51% of water-holding power) was beaten with a refiner at a treated concentration of 2% to obtain freeness (TAPPI Standard T227m- Measured according to 58) 375 ml, 254
Water retention capacity of 138 ml, 61 ml and 30 ml is 138 each
%, 151%, 181% and 195%.

In the case of softwood sulfite kraft pulp, untreated 705 ml freeness and 72% water retention capacity were treated with a Niagara beater at a treatment concentration of 2% to obtain freeness of 380 ml, 210 ml and 45 ml, respectively. %, 182% and 208%. In the case of mechanical pulp, the press type groundwood pulp had a freeness of 60 ml and a water holding power of 145%.

Thus, it can be seen that the method for producing finely ground pulp does not produce a product similar to the fine fibrous cellulose of the present invention even if it is ground to an extreme level. Another property of the fine fibrous cellulose of the present invention is that it retains its shape even when it contains water.

Examples of the fibrous cellulose to be used in the media agitation type wet pulverizer include bleached or unbleached softwood and hardwood chemical pulp, dissolved pulp, waste paper pulp, and even fibrous cellulose such as cotton, which has a high water retention ability. Fibrous cellulose can be obtained.

Water is basically used as a medium for the suspension to be treated, but it is chemically inert in the treatment process and is a fluid such as a lower alcohol, ethylene glycol or glycerin having a fluidity which can serve as a carrier for cellulose. Such an organic solvent or a mixed solvent with water can be used.

[0021]

EXAMPLES Specific examples of the present invention will be described below. Example 1 Using softwood bleached kraft pulp as a sample, the concentration was adjusted to 5 levels of 0.8%, 1.5%, 4%, 8% and 10% with water, and 120 g of a suspension of each concentration was prepared. , 125ml glass beads with an average particle size of 0.7mm
Was placed in a six-cylinder sand glider (processing capacity 300 ml) manufactured by IMEX Co., Ltd., and the rotation speed of the agitator was 2000 rpm.
Then, the treatment temperature was adjusted to about 20 ° C. by adjusting the temperature of the circulating water for cooling, and wet pulverization was performed in a batch system.

Table 1 shows the relationship between the treatment time at a treatment concentration of 1.5%, the number average fiber length, the fiber width and the water retention force as observed by scanning electron micrograph. Further, FIG. 1 shows the relationship between the number average fiber length and the water holding power. In Figure 1, ◯ indicates a density of 0.8%, ● indicates a density of 1.5%, and △ indicates a density of 3.5%.
The X mark shows that obtained at a concentration of 8%, and the ▲ mark shows that obtained at a concentration of 10%.

The number average fiber length is Finland KA.
It was measured with an FS-200 type fiber length measuring device manufactured by JAANI. As can be seen from FIG. 1, the water retention power increases as the treatment time increases and the number average fiber length decreases. As for the effect of the treatment concentration, when the same number average fiber length was compared, the lower the treatment concentration was, the higher the water retention capacity was.

[0024]

[Table 1]

Example 2 Softwood bleached kraft pulp was used as a sample and the concentration was 3% in water.
120 g of the suspension and 125 ml of glass beads having an average particle diameter of 1 mm as a medium were put into a six-cylinder sand grinder manufactured by IMEX Co., Ltd., and the temperature of the circulating water for cooling was 1500 rpm of the stirrer. While maintaining the treatment temperature at about 60 ° C. by adjustment, wet pulverization was performed in a batch system.

Table 2 shows the relationship between treatment time and water retention. As can be seen from Table 2, the water retention power increases as the treatment time becomes longer, and the water retention force is 325% when the treatment time is 3 hours.
I got that.

[0027]

[Table 2]

Example 3 Concentration 3 with water using a softwood sulfite pulp as a sample
%, And 120 g of the suspension and 125 ml of glass beads having an average particle size of 1 mm as a medium were placed in a six-cylinder sand grinder manufactured by IMEX Co., Ltd., and the circulating water for cooling was rotated at 1500 rpm of a stirrer. While maintaining the treatment temperature at about 60 ° C. by adjusting the temperature, wet pulverization was performed in a batch system.

Table 3 shows the relationship between treatment time and water retention. As can be seen from Table 3, as the treatment time becomes longer, the water retention power increases, and the water retention force is 332% after 3 hours.
I got that.

[0030]

[Table 3]

Example 4 Mechanical pulp (pressurized groundwood pulp) and waste paper pulp were used as samples, and each was prepared with water to a concentration of 2%.
125 ml of alumina beads having a diameter of 125 mm were placed in a six-cylinder sand grinder manufactured by IMEX Co., Ltd., and wet pulverization was carried out batchwise at a treatment temperature of about 20 ° C. by adjusting the temperature of circulating water for cooling.

Tables 4 and 5 show the relationship between the processing time and the water holding power of mechanical pulp and waste paper pulp, respectively. Table 4, Table 5
As can be seen from the above, the water retention capacity increased as the treatment time increased.

[0033]

[Table 4]

[0034]

[Table 5]

Example 5 Using a cotton linter as a sample, 120 g of a suspension prepared with water to a concentration of 2% was used to prepare an average particle size of 0.5 as a medium.
We put 125 mm zirconia beads in a container of a six-cylinder sand grinder made by Imex Co., Ltd., and perform wet milling in batch mode at a processing temperature of about 20 ° C. by adjusting the temperature of the circulating water for cooling at 2000 rpm of the stirrer. went.

Table 6 shows the relationship between treatment time and water retention.

[Table 6]

Example 6 Softwood bleached kraft pulp was used as a sample and its concentration in water was 1.
Glass beads 120 with an average particle size of 0.7 mm prepared to 5%
0 ml of Ultra Viscomil UVM manufactured by IMEX Co., Ltd.
-2600 (capacity 2L) in a container, sample suspension 1600
Wet grinding was carried out by continuously passing ml with a pump at a flow rate of 500 ml / min. The processing temperature was maintained at about 15 ° C. by circulating cooling water in the processing device. In the experiment, the sample coming out of the apparatus was put in a poly container and processed again by the crushing apparatus.

Table 7 shows the relationship between the number of treatments and the water holding power. As can be seen from Table 7, the water retention capacity also increased as the number of treatments was increased. Further, even if it was continuously passed through the apparatus, it could be processed without clogging in the apparatus.

[0039]

[Table 7]

Example 7 Using a softwood bleached kraft pulp whose fiber length was shortened in advance with a beater as a sample, the concentration was adjusted to 3% with water, and 1200 ml of glass beads having an average particle diameter of 1 mm were used and manufactured by Shinmaru Enterprises Co., Ltd. Dyno Mill Type KDL-PIL
Put in an OT type container, 2000ml of pulp suspension flow rate 40
Processing was carried out continuously at 0 ml / min. That is, the sample coming out of the processing device was put in a poly container and processed again by the crushing device. The processing temperature is about 15 ℃ by circulating cooling water through the processing equipment.
Kept at.

Table 8 shows the relationship between the number of treatments and the water holding power. As can be seen from Table 8, the water retention power increased as the number of treatments increased. Further, even if the treatment was continuously performed, the treatment could be performed without clogging in the apparatus.

[0042]

[Table 8]

Example 8 Using a hardwood bleached kraft pulp as a sample, 500 ml of a 1.5% pulp concentration suspension together with 975 ml of glass beads having an average particle diameter of 1 mm as a medium, Diamond Fine Mill MD-13 manufactured by Mitsubishi Heavy Industries, Ltd. The mixture was placed in a mold-type processing container, and wet-milled in batch mode with the agitator rotating at 1400 rpm.

Table 9 shows the relationship between treatment time and water retention. As can be seen from Table 9, the water retention power increases as the treatment time increases.

[0045]

[Table 9]

Example 9 Using hardwood bleached kraft pulp as a sample, a six-cylinder sand grinder manufactured by IMEX Co., Ltd. was used, the number of revolutions of the stirrer was 2000 rpm, and glass beads having an average particle size of 0.7 mm were used as media. The sample was processed using methanol and glycerin as suspension media. In methanol treatment, pulp dry weight 1.8 g, methanol 1
20 ml of glass beads, 120 ml of glass beads, and with glycerin treatment, 1.8 g of pulp dry weight, 12 glycerin
The experiment was conducted under the conditions of 0 ml and 120 ml of glass beads.

Tables 10 and 11 show the relationship between the treatment time and the water retention capacity when methanol and glycerin were used as suspensions, respectively. The water retention was measured by washing the treated sample with water. From Tables 10 and 11, it was found that even when methanol or glycerin was used as the suspension medium, the water retention power increased with the lapse of treatment time.

[0048]

[Table 10]

[0049]

[Table 11]

[0050]

EFFECTS OF THE INVENTION By treating fibrous cellulose with a media agitation type wet pulverizer, it is possible to efficiently obtain fine fibrous cellulose having high water retention.

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[Procedure amendment]

[Submission date] February 25, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Added

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the number average fiber length and the water retention capacity.

Claims (1)

[Claims] 1. A fibrous cellulose is subjected to a media agitation type wet pulverizer without causing substantial chemical change.
A method for producing fine fibrous cellulose, which comprises pulverizing the fine fibrous cellulose having a water retention capacity of 210% or more.