JPH0749606B2 - Method for treating pulp-like particles made of synthetic polymer - 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 treating pulp-like particles made of synthetic polymer. More specifically, the present invention relates to a novel treatment method for pulp-like particles obtained by introducing a solution of a synthetic polymer into a coagulation bath in which a high shearing force is applied to coagulate and fibrillate it, and to subject this to a special treatment. It is a thing.

[0002]

2. Description of the Related Art Pulp-like particles produced from synthetic polymers have been attracting attention as a material for electrical insulating materials because they are superior in heat resistance, electrical insulation and mechanical properties to natural pulp. For example, in Japanese Patent Publication No. 35-11851 and Japanese Patent Publication No. 37-5732, "Fibrid"
Pulp-like particles composed of a synthetic polymer referred to as are described in detail.

[0003] Such pulp-like particles, among them, pulp-like particles made of wholly aromatic polyamide or polyamide-imide which are excellent in heat resistance, flame retardancy, and electrical characteristics, or these and inorganic substances such as mica are compounded. Since the pulp-like particles are particularly excellent in electrical insulation, they are mixed with various heat-resistant fibers to form paper (sheet) form, and are widely used as electrical insulation.

In recent years, the pulp-like particles have been used as a friction material,
It has come to be used as a material for heat-resistant and flame-resistant sheets, honeycomb structure materials, electronic materials, and the like, and its applications have been expanded to various fields.

However, when the conventional pulp-like particles are used to produce paper (sheet) by wet papermaking, it is difficult to obtain a uniform paper with good papermaking properties, especially slow drainage from the papermaking wire mesh. It was difficult. Further, the pulp-like particles have a drawback that they are inferior in electric insulation when they are processed and used as an electric insulator.

[0006] Various studies have been carried out to improve such drawbacks, and some proposals have been made so far. For example, JP-A-51-96510 and JP-A-53-1.
No. 6070 discloses that the passing amount of 150 mesh wire mesh is 30 by the sieving degree test specified in JIS P8207.
In 80 wt% or 5 to 30 wt%, the pulp-like particles the average ratio values filtration resistance is 5-10 ³ ~100 × 10 ³ is to be suitable.

On the other hand, Katsuki Atsugi's "Pulp and Paper" describes the relationship between the drainage of natural pulp and the strength and elongation of the paper after paper making, and Yuichiro Take et al., "Electrical Insulation Paper". , The relationship between drainage and dielectric breakdown voltage is described.
This means that it is desirable that the pulp has a low drainage in order to obtain good paper, but on the other hand, a pulp having a low drainage has poor handleability and causes various problems in the washing and refining process. Has occurred.

The same applies to the case where a solution of a synthetic polymer is precipitated and solidified in a coagulation bath in which a shearing force is applied to form pulp-like particles, and pulp-like pulp having drainage capable of forming paper with good physical properties. When particles are to be produced, low drainage becomes a serious obstacle both when separating the pulp-like particles from the slurry after precipitation and when washing and purifying the separated pulp-like particles.

For this reason, there is a strong demand for pulp-like particles which are excellent in handleability in spite of the good physical properties of the paper after paper making, but at present, both satisfy the above-mentioned contradictory properties. No possible pulp-like particles are known.

[0010]

DISCLOSURE OF THE INVENTION The object of the present invention is that the handleability of pulp-like particles during washing with water is good, the papermaking (papermaking) properties are good, and the physical properties of the paper (sheet) after papermaking are also excellent. More specifically, it has a relatively low drainage property at the papermaking stage, exhibits excellent papermaking properties and physical properties after papermaking, and handles before that. It is an object of the present invention to provide a method for obtaining pulp-like particles which exhibit a relatively high drainage property and are easy to handle during washing, refining, etc.).

[0011]

DISCLOSURE OF THE INVENTION According to the present invention, a slurry containing pulp-like particles obtained by introducing a synthetic polymer solution into a coagulation bath in which a high shearing force is applied to coagulate and fibrillate the solution is rotated. The pulp-like particles are concentrated in a filter bed to reduce the freeness of the pulp-like particles to within a range of 20 to 30 degrees by a Shopper-Riggler method, and in that state, a washing treatment is carried out. And the freeness is increased by the Shopper-Riggler method within the range of 40 to 85 degrees, which is a method for treating synthetic polymer pulp-like particles.

Generally, a method for producing pulp-like particles made of a synthetic polymer is (a) a method of beating pulp made of a synthetic polymer to form pulp (for example, Japanese Patent Publication No. 59-603).
No.), (b) a method of precipitating the synthetic polymer obtained in the polymerization process as fibrils (for example, Japanese Patent Publication No. 47-248
No. 9, Japanese Examined Patent Publication No. 60-56801), (c) A method of precipitating fibrils (sometimes referred to as fibrid) by introducing a synthetic polymer solution into a coagulation bath in the presence of shearing force (Japanese Examined Patent Publication No. Sho). No. 35-11851, Japanese Patent Publication No. 37-5732
No.), the pulp-like particles of the present invention are obtained by the so-called precipitation method classified in the above (C).

The synthetic polymer constituting the pulp-like particles in the present invention is not particularly limited, and is, for example, a solvent-soluble synthetic high molecular weight polymer having a fiber-forming ability such as polyester, polyamide, polyamideimide, polyether and polycarbonate. Although they may be united, a wholly aromatic polyamide excellent in heat resistance, flame resistance, electrical properties, etc. is preferable.

From an industrial point of view, the wholly aromatic polyamide is a poly (m-phenylene isophthalamide) polymer, a poly (m-phenylene terephthalamide, isophthalamide) copolymer or a soluble in a polar amide solvent. P-phenylenediamine and 3,4 'as diamine components
-A wholly aromatic polyamide using diaminodiphenyl ether and a terephthalic acid halide as a dicarboxylic acid component (see Japanese Patent Publication No. 53-32838) is preferable.

As the solvent capable of dissolving the polymer, any solvent capable of dissolving the polymer may be used. In the case of the wholly aromatic polyamide, N-methyl-2-pyrrolidone, N, Polar amide solvents such as N'-dimethylformamide are preferred. These solvents may contain an inorganic salt such as lithium chloride and calcium chloride.

Since the viscosity of the solution has a great influence on the shape of the pulp-like particles to be obtained, it should be appropriately selected depending on the kind of the synthetic polymer, the solution composition, the precipitation conditions, etc. About 500 poise is suitable. At this time, the temperature of the solution can be adjusted to adjust the viscosity.

The precipitant forming the coagulation bath can be appropriately selected from liquids which are non-solvents for the above-mentioned polymer and have an affinity for the solvent in the polymer solution. Industrially, a mixture of the solvent in the polymer solution and the non-solvent (for example, water) is preferable, and in the case of the wholly aromatic polyamide solution, the polar amide solvent and the non-solvent currently used as the solution. Is preferred. In this case, the precipitation state can be adjusted by selecting the mixing ratio of the solvent and the non-solvent, and the pulp-like particles having desired morphology and characteristics can be obtained.

The apparatus for forming pulp-like particles (precipitator) can introduce a synthetic polymer solution into a coagulation bath to which a high shearing force is applied to cause precipitation in the form of fine leaflets or fibrils. If it is one, there is no particular restriction,
For example, a device equipped with a high-speed stirrer as described in JP-B-35-11851 or a tube type precipitation device as described in JP-B-37-5732 may be used, but JP-B-59-47.
A tubular flow channel stirring type continuous precipitation apparatus in which a stator and a rotor are combined as described in Japanese Patent No. 695 is particularly preferable.

The pulp-like particles thus obtained are in the form of a slurry dispersed in the liquid of the precipitating agent, and the pulp-like particles obtained from the slurry have a freeness (by the Shopper-Rigger method) of approximately. It is about 50 to 80 degrees.

In the method of the present invention, the above-mentioned slurry is used, for example, in Japanese Patent Application No. 61-38978 (JP-A-62-1999).
No. 00) has a peripheral wall mainly composed of a slanted cylinder having a wire mesh or a perforated plate as a peripheral wall, and is introduced into a rotary filter bed in which the subgrade surface is not submerged in the solution, and pulp-like particles are rotated with the rotation of the filter bed. Is separated from the filter bed surface, moves downward (forward), adheres to another position on the filter bed surface, and is separated again from the filter material surface to repeat the movement to concentrate the slurry, whereby pulp-like particles are obtained. The freeness (according to the Shopper-Riggler method, the same applies hereinafter) of is decreased to 20 to 30 degrees.

Generally, for concentration of the slurry, a concentration device such as a so-called rotary thickener in which the filter bed surface is constantly immersed in the discharged filtrate bath is used, but such a device has almost no freeness. It is not preferable because it does not decrease.

The freeness of the pulp-like particles is reduced to 20 to 30 degrees by the concentration treatment using the rotary filter bed as described above because the slurry-like pulp-like particles are separated from the filter bed surface during the concentration. It is presumed that the pulp-like particles having a thin leaf shape are rounded or the state of the fibrils is changed due to repeated movement-adhesion, so that the pulp-like particles undergo some form change.

In the method of the present invention, washing is carried out in such a state that the freeness is lowered to 20 to 30 degrees by such a concentration treatment.

According to the research conducted by the present inventors, the pulp-like particles immediately after being precipitated in water as described above are used, and the freeness is lowered to 20 to 30 degrees, washed with water, and then dispersed in water. No substantial difference in paper-making property was observed between when the paper was made with increased freeness. This means that the papermaking property is not adversely affected even if the freeness is once lowered to 30 degrees or less by the concentration treatment. However, if the freeness is less than 20 degrees, it is not preferable because the freeness often does not return to 40 to 85 degrees only by dispersing in water.

The pulp-like particles having a reduced freeness as described above are washed with water, and then put in water again for dispersion treatment to return the freeness to a range of 40 to 85 degrees. It has various properties. It is presumed that this peculiar property is due to the fact that the pulp-like particles return to the form before the concentration treatment only by performing the dispersion treatment in water. This dispersion treatment is preferably carried out by putting the pulp-like particles in water and stirring with a household mixer, a high-speed dissociator or the like.

The pulp-like particles according to the present invention have a freeness of 20 to 30 degrees, but the freeness returns to 40 to 85 degrees when dispersed in water. It is characterized in that its paper-making properties and the physical properties of the paper-made paper are almost unchanged compared to those immediately after precipitation.

On the other hand, the pulp-like particles according to the present invention have a freeness in the range of 20 to 30 degrees before dispersion in water, but those having a freeness in this range are excellent in handleability.
It has the feature that various treatments including water washing treatment can be performed easily.

Therefore, in the case of precipitation (formation of pulp-like particles) as in the method of the present invention, pulp-like particles having low drainage (high drainage), physical properties and paper-making properties are preferable, but difficult to handle. , Concentrate this to once convert it into pulp-like particles that have high drainage (low drainage) and are easy to handle, and after washing with water etc. in that state, disperse this into water to obtain physical properties. When the pulp-like particles having good paper-making property and low drainage (high freeness) are restored, the handleability is good and the paper-making properties are excellent throughout the pulp production, treatment and paper-making process.

When the pulp-like particles are washed with water by the method of the present invention, Japanese Patent Application No. 59-27, which has been already proposed by the present inventors, has been proposed.
It is preferable to use the apparatus of 398 (Japanese Patent Application Laid-Open No. 61-153154) to perform displacement washing under compression, but it is not limited to this.

[0030]

According to the method of the present invention as described above, the pulp-like particles can be easily treated and handled in the pulp-like particle production process such as separation and washing with water, and can be efficiently washed with water. In addition, it has the advantage that it cannot be combined with conventional pulp-like particles, that is, it has excellent paper-making properties and the physical properties of the paper made from paper, and it is extremely useful industrially.

The pulp-like particles according to the method of the present invention can be made into a good paper-like material by papermaking alone or by mixing with short fibers, inorganic materials and the like, and the obtained paper-like material is It can be widely used in various fields such as electric insulating materials, honeycomb materials, friction materials, and flame resistant materials.

[0032]

EXAMPLES Next, the present invention will be described in detail with reference to examples. In addition, the freeness in all examples is J unless otherwise specified.
It is a value measured by the Shopper Wrigler method specified in ISP8121. Further, η is the intrinsic viscosity (N-
(Measured with a methyl-2-pyrrolidone solution). B. in the table D. V. Is the dielectric breakdown voltage (KV / mm). Further, in the examples, "parts" means "parts by weight".

[0033]

Example 1 A poly (m-phenylene isophthalamide) polymer (η was 1.31 measured by dissolving it in N-methyl-2-pyrrolidone) was dissolved in N-methyl-2-pyrrolidone to obtain 12.5%. Solution. On the other hand, a 30% aqueous solution of N-methyl-2-pyrrolidone was prepared and used as a coagulating bath (precipitant).

Using the above polymer solution and coagulation bath, the device shown in Japanese Patent Publication No. 59-47695 (diameter 150 mm
The pulp-like particles were precipitated. On this occasion,
The supply ratio of the polymer solution and the coagulation bath was 60 parts of the polymer solution / 1800 parts of the coagulation bath, and the rotation speed of the rotor was 9000R.
PM.

The freeness of the obtained pulp-like particles was 70 degrees. However, the obtained pulp-like particles were simply filtered to dilute the water content of the cake, and the freeness of this pulp cake was measured. This pulp slurry has a special maximum diameter of 3
50mmφ, filtration area 0.72m ² , hold up 5
Concentration treatment was performed using a rotary filter bed of 0 liter and a rotation speed of 23 RPM. The freeness of the obtained pulp-like particles was 23.

After washing with water, the pulp-like particles were placed in water and dispersed in water with a household mixer. The mixer voltage was reduced to 70 volts (100 volt rating) and stirred for 4 minutes to disperse.

The freeness of the obtained pulp-like particles was 70 degrees. In addition, pulp-like particles / poly (m-phenyleneisophthalamide) fiber = 6/4 using these pulp-like particles
The physical properties of the paper-like material produced by (weight ratio) are shown in Table 1 below.

[0038]

[Table 1]

[0039]

Examples 2 to 4 In the same manner as in Example 1, poly (m-
Pulpy particles of (phenylene isophthalamide) were prepared and the freeness was changed by changing only the number of rotations with the same concentrating device.

The pulp-like particles were washed with water, dispersed in the same manner as in Example 1, the freeness was measured, and the paper was made in the same manner as in Example 1 to measure the physical properties of the paper.

The results are shown in Tables 2 and 3, and no significant difference was found other than the change in the freeness due to the change in the rotation speed.

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Embodiments 5 to 8] η = 1.35 in the same manner as in Embodiment 1.
Pulp-like particles were obtained using the polymer of poly (m-phenylene isophthalamide). The freeness of this pulp-like particle was 65.7 degrees. This was concentrated in the same manner as in Example 1 to reduce the freeness. However, the hold-up of the rotary filter bed was changed.

The results are shown in Table 4, and there was no remarkable difference in addition to the slight difference in the results due to the change in the holdup.

[0046]

[Table 4]

Further, the respective pulp-like particles were treated in the same manner as in Example 1 to make paper. The results are shown in Table 5 below.

[0048]

[Table 5]

[0049]

Example 9 Poly (m-phenyleneisophthalamide) having η = 1.32 was dissolved in N-methyl-2-pyrrolidone to prepare a 12.5% solution. On the other hand, a 30% aqueous solution of N-methyl-2-pyrrolidone was prepared as a coagulation bath solution. Pulp-like particles were produced in the same manner as in Example 1 using the polymer solution and the coagulation bath solution. The freeness of the obtained pulp-like particles was 67.5 degrees.

The obtained slurry of pulp-like particles was concentrated using a special rotary filter bed having a maximum diameter of 350 mmφ, a filtration area of 0.72 m ² and a holdup of 50 liters. The freeness after the treatment was 23.5 degrees.

The slurry of the pulp-like particles has an inner diameter of 250.
After being squeezed by a device described in Japanese Patent Application No. 59-273938 of mmφ into a hard disk-shaped cake, the cake is crushed by a crusher manufactured by Toho Tekko Co., Ltd.
It was replaced with water by the apparatus described in No.

The washing efficiency was very good, and almost no N-methyl-2-pyrrolidone contained in the pulp-like particles after washing was detected. The washed product was dispersed in water using a high-speed dissociator manufactured by Aikawa Iron Works. The freeness of the dispersed pulp-like particles was 67.5 degrees. The sieving result immediately after precipitation (pulping) and the sieving result after dispersion were the same.

The pulp-like particles were mixed with short fibers having a fineness of 2 denier and a length of 5 mm, which were composed of the same binder, and were made into paper by a Fourdrinier paper machine, and the physical properties of the paper after hot pressing had a strength of 9.5 /
4.5 (length / width) kg / mm ² , elongation 14.5 / 11.
It was 0 (vertical / horizontal)% and the dielectric breakdown voltage was 35.6 KV / mm.

[0054]

Example 10 and Comparative Examples 1 to 3 40 g (actual amount) of the pulp-like particles used in Example 2 having an inner diameter of 100 mmφ were used.
Water / pulp = 4/1 with the device described in 9-273938
The time when squeezed to was 4.0 minutes (Example 1
0).

On the other hand, the freeness of pulp-like particles when the same pulp slurry was treated with a rotary thickener manufactured by Ishigaki Kiko Co., Ltd. and the time required when the same water / pulp ratio was squeezed by the apparatus of Example 1 are shown in the following table. 6 (Comparative Example 1)
~ 3).

[0056]

[Table 6]

[0057]

Example 11 According to the method of Japanese Examined Patent Publication No. 53-32838, terephthaloyl chloride (50 parts by mole), p-phenylenediamine (25 parts by mole), 3,4'-diaminodiphenyl ether (25 parts by mole) were added to N- Methyl-2-
Polymerization was carried out by reacting in pyrrolidone to obtain an aromatic copolyamide having η = 3.2. The hydrochloric acid produced by the reaction is neutralized with calcium hydroxide so that the concentration of the aromatic copolyamide is 1
% -Diluted with N-methyl-2-pyrrolidone to obtain a solution, and the coagulation bath is N-methyl-2-using the apparatus (having a diameter of 80 mmφ) described in JP-B-59-47695.
Pulpy particles were prepared as a 30% aqueous solution of pyrrolidone. The freeness of the obtained pulp-like particles was 75 degrees.

The pulp-like particles were concentrated using the rotary filter bed used in Example 1. The freeness of the obtained pulp was 28 degrees.

This pulp was filtered with a Nutche type filter,
The pulp was washed with water by adding 50 times the amount of water. It took 30 minutes to wash with water. It was to be filtered without treatment with a rotary filter bed, and an attempt was made to add 50 times water to wash with water, but the water did not run out even after 1 hour and was given up.

The pulp, which had been treated with a rotary filter bed and washed with water, was dispersed with a household mixer at 60 volts for 5 minutes, and the freeness was 75 degrees.

The physical properties of the paper just made by the pulp dispersed in this household mixer and dried are the strength of 6.9.
It was kg / mm ² and the elongation was 7.9%.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshitaka Sakamoto 2-1, Hinodecho, Iwakuni-shi, Yamaguchi Teijin Limited Production Technology Research Institute (56) References JP-B-59-603 (JP, B2)

Claims (1)

[Claims] 1. A slurry containing a pulp-like particle obtained by introducing a solution of a synthetic polymer into a coagulation bath in which a high shearing force is applied to coagulate and fibrillate the solution is concentrated in a rotary filter bed. , The freeness of the pulp-like particles is reduced to a range of 20 to 30 degrees by a Shopper-Riggler method, and water washing treatment is performed in that state, and then the pulp-like particles are dispersed in water to obtain the freeness. Is raised by the Shopper-Riggler method within the range of 40 to 85 degrees, a method for treating pulp-like particles made of a synthetic polymer.