JPH06126143A - Method for dispersing liquid mixture with aggregate - Google Patents

Abstract

PURPOSE:To enable a liquid mixture with aggregates to be dispersed rapidly and uniformly by arranging the tip of a mobile nozzle to be pressed by a spring at an opposite position to the tip of a fixed nozzle which supplies the liquid mixture at high pressure, then forming a high pressure Slit part between both nozzle tips, and supplying the mixture under pressure so that a specific pressure difference is maintained across the slit. CONSTITUTION:The tip of a mobile nozzle 6 to be pressed by a spring 8 is arranged at an opposite position to the tip of a fixed nozzle 3 which supplies a liquid mixture with aggregates and a high-pressure slit part is formed between both tips. Further, the mixture is supplied under pressure so that a pressure difference of 250kg/cm<2> min. is maintained before and after the slit part. Consequently, it is possible to disperse the liquid mixture with the aggregates of fine particles uniformly and rapidly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dispersing an aggregate-containing liquid mixture for homogenizing dispersoids such as paints, inks, cosmetics, dispersion plating solutions and foods in a medium.

[0002]

2. Description of the Related Art Constituent components of a paint are manufactured by mixing and homogenizing them at an appropriate compounding ratio depending on the purpose of use. Among them, the pigment-colored coating material requires a pigment dispersion step in which the pigment is uniformly mixed in the vehicle and the agglomerated particles are separated into individual particles. Conventionally, in such a pigment dispersion step, as a homogenizing device for uniformly dispersing the pigment,
Ball mills, sand mills, colloid mills, etc. have been used.

In a ball mill, a large number of ceramic balls or steel balls are put as a grinding medium together with a pigment in a rotating cylinder, and the pigment is ground and mixed by friction and impact of the balls.
It is a device for dispersing. The sand mill is a device in which spherical sand of 20 to 40 mesh is put together with the pigment in a cylindrical container having an agitator whose inside is divided by several plates, and the pigment is dispersed by the flow of the sand. Further, the colloid mill device is a device for supplying the pigment to the gap between the disks having different rotational speeds to disperse the pigment.

In such a homogenizing apparatus, there is a problem that the homogenizing speed of the pigment is slow and it takes a long time. That is, in the ball mill or the sand mill, the pulverizing medium collides with the agglomerates of the pigment, and the agglomerates are destroyed and homogenized by the impact force, the collision of the pulverizing media, the shearing force at the time of separation and the like. However, the concentration of the pigment is not so high as about 30% by weight, and a part of the pigment is aggregated, so that the actual concentration of the pigment aggregate is lower. Therefore, if the pigment in such a state is to be homogenized by a ball mill or a sand mill, the grinding medium must collide with a pigment having a low concentration, that is, a small number of aggregates, and the probability is extremely low. Therefore, it is necessary to prolong the residence time of the pigment in the container and to reduce the amount of treatment once, which causes a decrease in the homogenization speed of the pigment.

Further, in the colloid mill, the pigments are supplied to the gaps between the discs having different rotations to break the aggregates and homogenize them. Therefore, it is necessary to set the gaps between the discs to be very narrow. Actually, the particle diameter of the pigment is about 15 μm, and it takes a very long time to supply the pigment to the gaps corresponding thereto. Therefore, the homogenization speed of the pigment becomes slower,
It also takes a long time. Especially in the case of high-viscosity pigments, the homogenization rate becomes slower.

Further, it has been considered to use a mesh filter having a very small opening, but there is a problem that the aggregate of dispersoids blocks the opening during the processing, which makes continuous processing impossible. It was On the other hand, the above-mentioned homogenizing device is troublesome to clean the device after use and requires a long working time. In particular, when the production of a large number of small quantities is required, a common facility that can be used repeatedly is required. However, ball mills and sand mills require that glass balls, steel balls, and sand as grinding media supplied into the container be taken out and washed each time they are used, and colloid mills have a relatively wide contact area with a disk. It was necessary to clean the surface and the work was very troublesome.

[0007]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems and to provide a method for dispersing an aggregate-containing liquid mixture for uniformly and rapidly dispersing an aggregate of fine particles. is there.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to a fixed nozzle tip for supplying an aggregate-containing liquid mixture at high pressure.
The tip of the moving nozzle, which is pressed by a spring, is arranged to face each other, a high-pressure slit is formed between the two, and the mixture is pressurized and supplied so that a differential pressure of 250 kg / cm ² or more is maintained before and after the slit. A method for dispersing an aggregate-containing liquid mixture, which comprises:

[0009]

The aggregate to be treated in the present invention has a primary particle diameter of several tens of μm or less, and includes submicron particles having a particle diameter of 1 μm or less and ultrafine particles having a particle diameter of 0.1 μm or less. In general, the smaller the particle size, the larger the surface area of the primary particles and the various cohesive forces (ionic force,
Van der Waals force) rapidly increases, and these primary particles aggregate to grow into aggregates of about 100 μm. The inventors of the present invention have made various investigations by paying attention to a method of generating shear stress by passing through minute gaps (slits) to disperse the agglomerates. Yes, since the viscosity and other physical properties of these liquid mixtures change intricately with changes in particle size, if the slit width is fixed and homogenization treatment is performed,
The slit part causes blockage due to large particles and a sharp increase in pressure loss, making it difficult to process at a stable constant flow rate.

Therefore, the present inventors have made it possible to vary the slit width by utilizing the force of the spring without fixing the slit width, and control the force of the spring and the supply pressure of the aggregate-containing liquid mixture, 250 kg / cm ² differential pressure before and after slitting
As mentioned above, considering the performance and economy of the pump, it is 300 to 60.
It has been found that by maintaining a differential pressure in the range of 0 kg / cm ² , it is possible to surely disperse various aggregate-containing liquid mixtures in a short time and to process at a stable constant flow rate.

FIG. 1 is a cross-sectional view of an aggregate-containing liquid mixture dispersion device for carrying out the method of the present invention. A fixed nozzle 3 is housed in the lower casing 2 and fixed by a pressing portion 4. The fixed nozzle 3 is sealed by a seal portion 5 such as an O-ring, and the rear end of the pressing portion 4 is connected to the inlet line 10 of the aggregate-containing liquid mixture.
On the other hand, the moving nozzle 6 is accommodated in the upper casing, and is pressed by the spring 8 from the rear part, and the pressing force is adjusted by the holding screw 9. A seal portion 7 is provided around the moving nozzle 6. Further, the shape of the fixed nozzle 3 is excellent in strength when its tip is in contact with the moving nozzle 6 in a plane and has a trapezoidal cross section, and is easy to manufacture. Further, the fixed nozzle 3 and the moving nozzle 6 are preferably made of a material having a hardness higher than that of the agglomerate, and those coated with diamond are suitable because they have the highest wear resistance.

FIG. 2 shows a paint preparation device incorporating the dispersion device of FIG. 1, in which a raw material storage tank 12 is charged with a liquid mixture 13 composed of a pigment, a varnish and a solvent, which is pressurized by a pump 14. It is introduced from the inlet line 10 into the lower casing 2 of the dispersing device of FIG. 1, and is supplied to the slit portion formed by the fixed nozzle 3 and the moving nozzle 6. The slit width of the slit portion is determined by the differential pressure before and after the slit portion and the pressing force of the spring 8 that presses the moving nozzle 6,
It is pushed out from the slit gap at a predetermined flow rate and a predetermined pressure, discharged from the fluid outlet line 11, and stored in the product receiving tank 15. For the recovered paint, measure the maximum particle size of the pigment agglomerated particles by the tube gauge method, and inspect whether the paint specifications are satisfied.

By the way, the pigment is an ultrafine particle having a particle size of submicron, but since the medium has a viscosity of several tens of poise and a viscosity of about 1000 times that of water, when both are roughly mixed, it is about 100 μm. Agglomerated particles of. Then, in order to disperse this into a standard particle size of the paint of about 10 to 20 μm, a very large amount of energy is required. However, when a paint is prepared using the above equipment, line 10 and line 1
The larger the differential pressure of 1, the more effective the dispersion is, but from the viewpoint of pump capacity and economical efficiency, 300 to 600 kg is required for the preparation of the paint.
It is preferable to maintain the differential pressure in the range of / cm ² .

[0014]

【Example】

(Example) Using the apparatus shown in FIGS. 1 and 2, the particle size is 0.5 μm.
The following simulated paint crude mixture consisting of 40 wt% TiO ₂ , 50 wt% varnish and 10 wt% toluene was prepared. The average particle size of the aggregate was about 130 μm. next,
This crude mixture is pressurized to 500 kg with the pump of the apparatus shown in FIG.
The pressure was increased to / cm ^2, and the slit portion was passed through the high pressure slit nozzle of FIG. The same operation was repeated 5 times in total, and the maximum particle diameter in the treatment liquid was measured by the tube gauge method. As shown in FIG. 3, the particle diameter can be greatly reduced by repeating the pass, and the flow rate is 57. ~ 60k
It was confirmed that it was almost constant in the range of g / h. By the way, when 5 passes were performed at a pressure of 200 kg / cm ² ,
The maximum particle size was 50 μm, and the dispersion effect was significantly reduced.

(Comparative Example) In the dispersion device of FIG. 1, the movable nozzle is fixed to form a fixed high-pressure nozzle, and a thin plate having a known thickness is inserted into the slit gap for each pass to adjust the slit width. When the same experiment was carried out by adjusting as shown in FIG. 4 and maintaining the pressure difference before and after the slit portion at 500 kg / cm ² , as shown in FIG. 4, the particle size reduction rate decreased with each pass, and , It was found that the processing amount decreased for each pass.

[0016]

According to the present invention, by adopting the above constitution, it becomes possible to uniformly disperse a liquid mixture containing an aggregate of fine particles in a short time.

[Brief description of drawings]

1 is a cross-sectional view of an apparatus for dispersing an aggregate-containing liquid mixture for carrying out the method of the present invention.

FIG. 2 is a conceptual diagram of a paint preparation device incorporating the dispersion device of FIG.

FIG. 3 is a graph showing changes in maximum particle size and flow rate with respect to the number of passes in the example.

FIG. 4 is a graph showing changes in maximum particle diameter and flow rate with respect to the number of passes in a comparative example.

[Explanation of symbols]

1 upper casing, 2 lower casing, 3 fixed nozzle, 4 pressing part, 5 sealing part, 6
Moving nozzle, 7 seal part, 8 spring, 9 cap screw part, 10 inlet line, 11 outlet line,
12 raw material storage tank, 13 aggregate-containing liquid mixture, 1
4 pumps, 15 product tanks

Continued Front Page (72) Inventor Tetsuya Tanimoto 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Yoshisho Kakiuchi 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryoh Heavy Industries Co., Ltd. (72) Inventor Hiroshi Sato 1382-12 Shimoishigami, Otawara-shi, Tochigi Dai Nippon Paint Co., Ltd. (72) Kaoru Yoshida 6-1-12, Nishikujo, Konohana-ku, Osaka, Osaka Nippon Paint Co., Ltd.

Claims (1)

[Claims] 1. A method for dispersing an aggregate-containing liquid mixture, wherein a moving nozzle tip pressed by a spring is arranged opposite to a fixed nozzle tip for supplying the mixture under high pressure, and a high pressure slit portion is provided between the two. To maintain a differential pressure of 250 kg / cm ² or more before and after the slit portion,
A method for dispersing an aggregate-containing liquid mixture, which comprises supplying the mixture under pressure.