JPH0461687B2 - - Google Patents

Description

[Detailed description of the invention] a. Industrial application field The present invention is directed to core particles (hereinafter referred to as base particles).
As a method, particles with various surface shapes such as irregularities, pores, and grooves are used to attach and embed other particles (hereinafter referred to as child particles) in advance on the surface and recesses of the mother particles. The protrusions of the base particles are then softened, melted, and
This invention relates to a method for surface modification of mother particles by deforming the mother particles and enveloping child particles in the mother particles.

b Conventional technology Conventionally, in general, prevention of caking of solid particles, prevention of discoloration and deterioration, improvement of dispersibility, improvement of fluidity, improvement of catalytic effect, control of digestion and absorption, improvement of magnetic properties, improvement of color development, and light resistance. Various surface modifications have been carried out for the purpose of improving properties, such as physical adsorption, chemical adsorption, vacuum evaporation, electrostatic adhesion, molten substance coating, and special spray drying. . Among these, in particular, the surface of solid particles is
In other words, when modifying the surface of powder with powder,
Modification has been carried out by stirring for a long time (several hours to several tens of hours) using various known mixer type or ball mill type stirrers, and applying the electrostatic and mechanochemical phenomena that occur with stirring. Ta.

c Problems to be Solved by the Invention In the conventional method, the child particles are only attached to the surroundings of the mother particles, and the adhesion of the child particles to the mother particles is not sufficient. When processing processes such as mixing, kneading, dispersing, and pasting are performed in the next process, the child particles may easily fall off or the components may become unbalanced, which not only severely limits the operating conditions, but also severely limits the production efficiency after processing. This was the biggest cause of variations in product quality.

Furthermore, various microencapsulation methods have been used to control the sustained release of substances, but all of them are wet methods, and not only do they require a drying process as the next step, but the field of application of the technology is also limited. It was limited and lacked versatility.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a method for surface modification of solid particles that solves the above-mentioned problems of the prior art.

d. Means for Solving the Problems In order to solve the above-mentioned problems, the present invention, as shown in FIG. melting,
Alternatively, by deforming the mother particles and enveloping the child particles in the mother particles, the surface of the powder particles can be uniformly and stably modified in an extremely short period of time (several seconds to several minutes), thereby producing functional composite materials (hybrid powders). )
The purpose is to provide a method that can obtain the following: A rotary disk surrounding an impact pin is placed in an impact chamber, and a rotational disk is provided along the outermost orbital surface of the impact pin, and at a constant distance with respect to the outermost orbital surface of the impact pin. A collision ring is arranged with a space therebetween, and airflow generated by the rotation of the impact pin is circulated through the impact chamber and a part of the impact ring to the front cover near the center of the rotary disk. The airflow is guided and circulated through a circuit, and together with the airflow, solid particles with an average particle diameter of 100 to 0.1 μm have irregularities, holes, and grooves of various shapes on the surface, and it is possible to enter the inside of the recesses, holes, and grooves of the solid particles. The entire amount of powder particles consisting of other fine solid particles of a size as large as possible is repeatedly passed through the impact chamber and the circulation circuit, and the solid particles are removed between the impact pin and the collision ring. While or after adhering and embedding the other microscopic solid particles inside the recesses, holes, and grooves of the solid particles, the convexity of the solid particles is caused by mechanical impact within a range that does not crush the particles. The convex portions of the solid particles are softened, melted, or further deformed by continuous mechanical impact or thermal energy generated by the mechanical impact, and the other fine solid particles are formed inside the solid particles. The present invention provides a method for surface modification of solid particles, which is characterized by forming a composite in a state in which the particles are encapsulated.

Typical base particle powders that can be surface-treated by the method of the present invention generally have an average particle diameter of 0.1 μm to
Nylon powder, polyethylene powder, acrylic powder, styrene powder, ABS powder, polypropylene powder, gelatin, various waxes, sulfur, copper powder, which are approximately 100μm in size and have various surface shapes such as irregularities, holes, and grooves. Organic substances, inorganic substances, metals such as silver powder, and typical child particle powders generally have a parallel particle diameter of 0.01 μm.
Pigments such as titanium dioxide, carbon, and iron oxide with a diameter of ~10μm, polymeric materials such as epoxy powder, nylon powder, and acrylic powder, metals such as tin, silver, and copper, starch, cellulose, silk powder, and ceramics. These include natural materials such as herbs and various powdered fragrances. However, the present invention is not limited to these materials;
Combinations of various materials used in various chemical industries, electrical industries, magnetic materials industries, cosmetics, paints, printing inks, toners, coloring materials, textiles, pharmaceuticals, foods, rubber, plastics, ceramics, and other industries. Can be applied to ingredients.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 2 and 3 show an example in which an impact crusher is used as impact impact means for carrying out the method of the present invention. In the figure, 1 is a casing of a powder impacting device (a typical impact crusher) used to carry out the method of the present invention, 2 is a cover afterwards, and 3
4 is a front cover, 4 is a rotary disk that rotates at high speed inside the casing 1, and 5 is a plurality of impact pins radially arranged at predetermined intervals around the outer circumference of the rotary disk 4, which are generally hammer-shaped. Or a plate type one. Reference numeral 6 designates a rotating shaft that rotatably supports the rotary disk 4 within the casing 1, and 8 designates a collision ring disposed around the outermost orbital surface of the impact pin 5 with a certain space therebetween. , this uses various shapes of concave and convex type or circumferential flat plate type. Reference numeral 9 denotes an on-off valve for discharging modified powder, which is provided by cutting out a part of the collision ring, and in some cases, this may be provided by cutting out a part of the front cover or rear cover facing the grinding chamber. . 10 is the valve shaft of the on-off valve 9, 1
1 is an actuator that operates the on-off valve 9 via the valve shaft 10; 13 has one end opening in a part of the inner wall of the collision ring 8, and the other end opening in the front cover 3 near the center of the rotary disk 4; a circular circuit that forms a closed circuit,
14 is a raw material hopper, 15 is a raw material supply chute that connects the raw material hopper 14 and the circulation circuit 13, 16 is a raw material measuring feeder, and 17 is a raw material storage tank. Reference numeral 18 indicates a shock chamber provided between the outer periphery of the rotary disk 4 and the collision ring 8, and reference numeral 19 indicates a circulation port to the circulation circuit 13. 20 is a modified powder discharge chute, 21 is a cyclone, 22 is a rotary valve, 23 is a bag filter, 24 is a rotary valve, 25 is an exhaust fan, 31 is a time control device for controlling the operation of the present invention, and 32 is a preset Various types of mixers, electric mortars, and other known preprocessors used when it is necessary to attach child particles to the surface of particles are shown.

When carrying out the powder surface modification method of the present invention using the above apparatus, the following procedure is performed.

First, the on-off valve 9 for discharging the reformed powder is kept in a closed state, and the rotating shaft 6 is driven by a driving means (not shown) while introducing inert gas into the apparatus as necessary. The rotary disk 4 is rotated at a circumferential speed of 5 m/sec to 160 m/sec depending on the properties of the substance to be modified. At this time, the impact pin 5 on the outer periphery of the rotary disk 4
A sudden air/inert gas airflow is generated as the airflow rotates, and due to the fan effect based on the centrifugal force of this airflow, the airflow rotates around the circulation circuit 13 from the circulation port 19 of the circulation circuit 13 that opens into the shock chamber 18. A circulating flow of airflow returning to the center of the plate 4, that is, a completely self-circulating flow is formed. Furthermore, since the amount of circulating air generated per unit time is significantly larger than the total volume of the shock chamber and circulation system, an enormous number of air circulation cycles are formed in a short period of time.

Next, a powder to be treated, in which child particles are attached to the recesses of a predetermined amount of mother particles using, for example, an electrostatic phenomenon, is fed into the raw material hopper 14 from the metering feeder 16 in a short time. If it is not necessary to use the preprocessor 32, the mother particles and child particles are weighed separately and placed into the raw material hopper 14. The powder to be processed passes from the raw material hopper 14 through the chute 15 and enters the shock chamber 18 . The powder particles sent into the impact chamber 18 are instantaneously impacted by the many impact pins 5 of the rotary disk 4 that rotates at high speed, and then collide with the surrounding impact ring 8 to be struck again. Subject to impact action and strong compression action. At the same time, the powder to be treated is circulated through the circulation circuit 13 along with the flow of the circulating gas, returns to the impact chamber 18, and is again subjected to the impact action.

Such an impact action is repeated many times in a short period of time, and the surface of the base particle, especially the convex part of the base particle, receives the impact, impact action, and (thermal) energy from this action, resulting in a short period of time. Softening inside,
The mother particles are melted and deformed, and a film of the mother particles is formed on the surface of the mother particles in a state where the child particles are encapsulated in the mother particles.
This series of impact actions is continued until the entire surface of the base particles is in the desired fused state, but a large amount of gas (air and inert gas) is inside the system compared to the total volume of the impact chamber and circulation system. As a result, the powder to be treated (mother particles and child particles) that circulates together with the gas is subjected to a huge number of impacts in an extremely short period of time. Although it depends on the amount of treatment per batch, the time required for this surface modification is generally completed within an extremely short time of several seconds to several minutes, even including the time for supplying the powder to be treated.

Figure 1 shows a model diagram. In the figure, a is the base particle, and its surface morphology includes various shapes of unevenness, pores, etc.
It has a groove-like shape. b is a child particle. Figure 1 shows the raw material system, and Figure 2 shows the state in which the child particles are attached to the concave portions of the mother particles. In this state, by applying the above-mentioned impact or impact action, a part (convex part) of the base particle softens, melts, or deforms, and the particle moves as shown in Figures 3 and 4, and the child particles are wrapped in the base particle. become.

After the above immobilization work is completed, the on-off valve 9 for discharging the modified powder is moved to the position shown by the chain line and opened, and the powder subjected to the immobilization process is discharged. This fixed powder is affected by the centrifugal force acting on itself (the discharge valve 9 may be located at a different location as long as the centrifugal force is acting on the treated powder).
Then, it is discharged from the shock chamber 18 and the circulation circuit 13 in a short period of time (several seconds) by the suction force of the exhaust fan 25, and is discharged from the cyclone 21 and circulation circuit 13 through the chute 20. 21 and a bag filter 23, the powder is collected and discharged to the outside of the system via rotary valves 22 and 24.

After discharging the immobilized powder, the on-off valve 9 is immediately closed, and a certain amount of the powder to be treated for the next time is supplied to the shock chamber from the metering feeder 16 again and undergoes the same process to be immobilized. powder is produced one after another. Note that these series of batch fixing processing operations are controlled and continued by a time limit control device 31 whose time limit is set in advance in relation to the operating time of related equipment.

If the softening, melting, and film-forming treatment by the base particles on the surface of the base particles can be carried out by local fixation, the powder impact apparatus shown in FIG. 2 can also be used as a one-pass continuous processing system. In that case, the powder to be treated may be continuously supplied from the raw material hopper 15 with the circulation port 19 in FIG. 2 closed and the on-off valve 9 open.

In addition, during the surface modification treatment operation according to the present invention, if it is necessary to use thermal treatment as an auxiliary, the collision ring 8 and circulation circuit 13 may have a jacket structure.
Temperature conditions convenient for surface modification treatment of the powder to be treated can be set through various heating mediums and coolants.

In addition, in the powder impacting device used for carrying out the present invention, auxiliary blades are attached to the rotary disk 4, or a centrifugal plate fan or the like is placed in the middle of the circulation circuit 13 to further force the circulating flow. It can also be empowering. That is, if the circulating air volume is increased, the number of times of circulation within a unit time increases, and therefore the number of collisions of powder particles also increases, so that the surface modification treatment time can be shortened.

Furthermore, the powder impacting apparatus used in the practice of the present invention is not limited to the one provided with the above-mentioned circulation circuit, but also includes one having a structure in which the circulation circuit is removed from the apparatus shown in FIGS. 2 and 3. can be used.

In addition, the atmosphere in which the present invention is carried out is in the air, and the combination of particles prevents oxidative deterioration.
Nitrogen gas or various inert gases may be used to prevent ignition or explosion.

FIG. 4 shows an example in which this inert gas is used in a powder impacting device which is also used in the practice of the present invention. In the description of this embodiment, the same members as in the previous embodiment are designated by the same reference numerals, and the explanation thereof will be omitted. In FIG. 4, 26 is the raw material hopper 14
27 is an inert gas supply valve that opens into the raw material supply chute 15;
Reference numeral 8 indicates an inert gas supply source, and 29 indicates an inert gas supply path. Note that this embodiment shows an embodiment in which the circulation circuit 13 is housed within the casing 1.

When starting the operation, first, the raw material supply valve 26 is closed, the on-off valve 9 is opened, and then the inert gas supply valve 27 is opened to fill the shock chamber 18 and circulation circuit 13 with inert gas. The substitution of inert gas into the shock chamber and circulation circuit prior to the start of this immobilization work is usually completed within a few minutes.

Next, after closing the on-off valve 9 and the supply valve 27 at the same time, the raw material supply valve 26 is immediately opened, and the pre-measured powder to be processed is passed through the chute 15 into the shock chamber 1.
Supply to 8. After supplying, the supply valve 26 is immediately returned to the closed state, and upon receiving this signal, the weighing feeder 16 measures and supplies the next powder to be processed to the raw material hopper 14.

Thereafter, the powder to be treated is bombarded with an inert gas in the same manner as in the above embodiment, and the powder to be treated is reformed while being circulated in the circulation circuit 13 while maintaining sufficient contact with the inert gas. It is processed. Next, when the on-off valve 9 and the supply valve 27 are opened, the immobilized powder is transferred from the shock chamber 18 and the circulation circuit 13 to the chute 2.
0 and at the same time shock chamber 18 and circulation circuit 1.
3 is replaced with a new inert gas. The discharged surface-modified powder is treated in the same manner as in the previous example.

Thereafter, by closing the on-off valve 9 and the supply valve 27 and opening the raw material supply valve 26, the next reforming operation will proceed. Note that this series of batch fixing operations including supply and stop of the inert gas are controlled and continued by the time control device 31 as in the previous embodiment.

If the softening, melting, or deformation of the base particles only needs to be done in a localized area, the powder impacting apparatus shown in FIG. 4 can be used as a continuous treatment system in a one-pass chamber. In that case, the circulation circuit 13 shown in FIG. It should be supplied at a ratio of . At this time, if a method is adopted in which the inert gas at the outlet of the exhaust fan (25 in FIG. 2) is returned to the raw material supply chute 15, the amount of inert gas used can be reduced, which is economical.

As mentioned above, the features of the method for surface modification of solid (powder) particles according to the present invention are that the impact-type crushing mechanism as an impact-type impact means has a strong impact force on the fine powder particles, and the Focusing on surface morphology,
The process involves using impact force to envelop child particles within the parent particle.

Furthermore, as shown in FIG. 1, according to the method of the present invention, the envelopment of the child particles into the mother particles of various materials is not limited to just one-component molecular particles;
It is also possible to encapsulate child particles of two or more components. Further, the shape of the child particles is not restricted, such as spherical, amorphous, and fibrous.

In addition, according to the method of the present invention, when the ratio (ratio) of the contained child particles to each base particle does not need to be so strict (that is, when the overall component ratio only needs to be constant), various types of mixers can be used. It is possible to immobilize the child particles on the surface of the mother particle by directly supplying separately measured mother particle powder and child particle powder to the impact chamber without using a preprocessor such as an electric mortar.

Example 1 The powder impact device shown in FIG. 2 was used, in which the outer diameter of eight plate-type impact pins disposed around a rotary disk was 235 mm, and the diameter of the circulation circuit was 54.9 mm. Acetylene black with an average particle diameter of dp ₅₀ = 0.03 μm was mixed and adhered as a child particle to porous nylon 6 with an average particle diameter of dp ₅₀ = 19 μm as a base particle in advance using a mixer, and then powdered at a rotation speed of 6540 rpm using the above processing device. When processed under the conditions of 120 g of body charge and 2 min of operation time, a surface-modified powder was created in which acetylene black (child particles) were wrapped in nylon particles (mother particles), and the surface was further covered with nylon 6. Obtained.

Incidentally, a scanning electron micrograph of the powder sample used in the above example is shown in FIG.

e Effects of the Invention As described above, according to the method for surface modification of solid particles according to the present invention, the surface morphology of the mother particles made of a combination of various powder materials is utilized to transform other child particles into the mother particles. By performing a surface modification treatment that envelops the material, it is possible to efficiently produce a functional composite/hybrid powder material (composite or hybrid powder) with uniform and stable properties in an extremely short time.

[Brief explanation of drawings]

1 to 4 are conceptual explanatory diagrams showing the aspects of various pre-modified powders and modified powders treated by the method according to the present invention, and FIG. A conceptual explanatory diagram systematically showing the powder impacting device that was used, along with its front and rear devices, Figure 3 is a side cross-sectional diagram of Figure 2, and Figure 4 is another device that also uses inert gas. FIG. 5 shows a scanning electron micrograph of the particle structure of the powder sample used in the example, and FIG. 1 shows the porous nylon raw material (2000x) used in the example, 3 shows a state in which child particles are attached to a mother particle (5000 times), and 3 shows a state in which the child particles are encapsulated within the mother particle after surface modification by impact impact means (5000 times). a...Mother particle, b...Child particle, 1...Impact type crusher.

Claims (1)

[Scope of Claims] 1. A rotary disk surrounding an impact pin is arranged in an impact chamber, and a collision ring is arranged along the outermost orbital surface of the impact pin and with a certain space therebetween. , the airflow generated by the rotation of the impact pin is guided and circulated through the impact chamber and a circulation circuit that opens from a part of the impact ring to the front cover near the center of the rotary disk; In addition, the average particle size has various shapes of unevenness, pores, and grooves on the surface.
The entire amount of the powder particle group consisting of solid particles of 100 to 0.1 μm and other minute solid particles of a size that can fit inside the recesses, holes, and grooves of the solid particles is repeatedly removed as described above. The solid particles are passed through the impact chamber and the circulation circuit, and the solid particles are mechanically hit within a range that does not crush the solid particles between the impact pin and the collision ring, so that the solid particles are inside the recesses, holes, and grooves of the solid particles. While adhering and embedding fine solid particles, or after adhering and embedding, the convex portions of the solid particles are deformed, and the solid particles are further deformed by continuous mechanical impact or thermal energy generated by the mechanical impact. A method for surface modification of solid particles, which comprises softening, melting, or further deforming the convex portions of the solid particles to form a composite in a state in which the other fine solid particles are encapsulated inside the solid particles. 2. The method for surface modification of solid particles according to claim 1, characterized in that all or part of adjacent convex portions of the solid particles are fused to each other. 3. The method for surface modification of solid particles according to claim 1 or 2, which comprises adhering other fine solid particles to the inside of the recesses, holes, and grooves of the solid particles in advance. . 4. The method for surface modification of solid particles according to any one of claims 1 to 3, characterized in that heating is used as an auxiliary means to fuse adjacent convex portions of the solid particles to each other. 5. A method for surface modification of solid particles according to any one of claims 1 to 4, characterized in that the method is carried out under an inert gas atmosphere.