JP2840642B2 - Resin granulation method and apparatus - 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 and an apparatus for producing a resin powder by spray cooling granulation.

[0002]

2. Description of the Related Art Mechanical pulverization, chemical pulverization, spray cooling granulation and the like are known as methods for producing resin powder. In spray cooling granulation, a molten resin is sprayed, cooled and solidified. Therefore, it is characteristic that true spherical particles are obtained.
There are several types of spraying methods.The disk atomizing method is a method in which a stock solution is supplied to a high-speed rotating disk and sprayed by centrifugal force.The particle size can be easily changed by changing the number of rotations of the disk. Control,
Suitable for small lot multi-product production.

However, when a molten resin is spray-cooled and granulated by a disk atomizing method, if the disk is not sufficiently heated, the supplied resin is cooled on the disk, so that the viscosity increases and the powder having a small particle size is formed. However, there was a problem that it became difficult to perform, or the hardening occurred on a disk.

[0004] As a method of heating the disk, it is conceivable to directly blow hot air having a temperature equal to or higher than the melting point of the resin onto the disk, separately from hot air which governs the ambient temperature equal to or lower than the melting point of the resin. However, in this method, the temperature and amount of the hot air and the shape of the outlet of the hot air were examined, but it was difficult to prevent the mixing of the two hot air, and the disk could not be heated effectively.

The present inventors have made intensive studies and found that the problem can be solved by directly heating the disk by induction heating as a completely new method, and completed the present invention.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a spray cooling granulation method and apparatus for heating a disk by induction heating in spray cooling and granulating a molten resin by a disk atomizing method. . In other words, a coil is installed very close to the top or bottom of the disk, and a high-frequency rotating disk is induction-heated by connecting a high-frequency generator to this coil, and a molten resin stock solution is supplied thereto to perform spray cooling granulation. Is what you do. Induction heating utilizes a phenomenon in which an eddy current is generated in a magnetic body such as iron near the coil by an alternating magnetic field generated by the coil, and the magnetic body generates heat. Although there is a limit to the material that can be heated, the object to be heated itself generates heat, so that the loss is small and there are many applications. A familiar example is an electromagnetic cooker.

The resin used in the present invention may be any resin as long as it has fluidity when heated, and examples thereof include polyethylene, polypropylene, polystyrene, polyester, and polyamide.

The material of the disk used in the present invention is desirably iron, but any magnetic material can be used because it generates heat regardless of the efficiency. It is also possible to use a material in which iron is embedded in a non-magnetic material, or a material in which the surface of iron is coated with paint or plated.

The temperature of the disk depends on the conditions such as ambient temperature, stock solution temperature, stock solution supply amount, etc., but is preferably higher than the fluidization temperature of the raw material, and more preferably equal to or higher than the stock solution temperature. In particular, setting the disk temperature higher than the stock solution temperature is advantageous in the following respects.
That is, in order to produce a powder having a small diameter, it is better that the melt viscosity is low. However, if the temperature of the undiluted solution is increased, there is a disadvantage that thermal degradation of the resin is likely to occur. Thus, if the temperature of the disc is set high without increasing the temperature of the stock solution, the powder is heated on the disc in a short period of time and the viscosity decreases, so that fine powder can be produced without thermal degradation of the resin. For the same reason, there is an advantage that a raw material having a slightly higher melt viscosity can be used.

Next, the present invention will be further described with reference to Examples and Comparative Examples.

[0011]

EXAMPLE 1 A coil was mounted under a disk having a diameter of 100 mm as shown in FIG. 1 and connected to a 1 kW high frequency generator, and the disk temperature was set at 250 ° C. Ambient temperature 140
° C, spin the disc at 25000 rpm,
The relative viscosity of the 0.5% meta-cresol solution at 1.
A stock solution obtained by heating Nylon 12 (melting point: 175 ° C.) to 250 ° C. was supplied at 2.5 kg / hr. The product obtained at this time was a white powder having an average diameter of 35 μm.

[0012]

Example 2 As shown in FIG. 1, a coil was mounted under a disk having a diameter of 100 mm, connected to a 1 kW high frequency generator, and the disk temperature was set at 350.degree. Ambient temperature 140
° C, spin the disc at 25000 rpm,
The relative viscosity of the 0.5% meta-cresol solution at 1.
A stock solution obtained by heating Nylon 12 (melting point: 175 ° C.) to 250 ° C. was supplied at 2.5 kg / hr. The product obtained at this time was a white powder having an average diameter of 10 μm.

[0013]

Embodiment 3 As shown in FIG. 1, a coil was mounted under a disk having a diameter of 100 mm, connected to a 1 kW high frequency generator, and the disk temperature was set at 350.degree. The temperature of the atmosphere was 140 ° C., the disk was rotated at 25000 rpm, and the relative viscosity of a 0.5% meta-cresol solution at 25 ° C. was 1.4 in nylon 12 (melting point: 178 ° C.).
A stock solution heated to 250 ° C. was supplied at 2.5 kg / hr. The product obtained at this time was a white powder having an average diameter of 40 μm.

[0014]

Comparative Example 1 As shown in FIG. 2, the ambient temperature was set at 140 ° C., and the hot air for heating the disk was set at 250 ° C. The measured temperature of the disk at this time was 165 ° C. The disk was spun at 25000 rpm, and the
A stock solution obtained by heating nylon 12 (melting point: 175 ° C.) having a relative viscosity of 5% meta-cresol solution of 1.2 to 250 ° C. was supplied at 2.5 kg / hr. The product obtained at this time was white floc.

[0015]

Comparative Example 2 As shown in FIG. 2, the ambient temperature was set at 140 ° C., and the hot air for heating the disk was set at 350 ° C. The measured temperature of the disk at this time was 200 ° C. The disk was spun at 25000 rpm, and the
A stock solution of nylon 12 (melting point: 175 ° C.) having a relative viscosity of 5% meta-cresol solution of 1.2 and heated to 250 ° C. was supplied at 2.5 kg / hr. The product obtained at this time was a white powder having an average diameter of 100 μm.

[0016]

Comparative Example 3 As shown in FIG. 2, the ambient temperature was set at 140 ° C., and the hot air for heating the disk was set at 350 ° C. The measured temperature of the disk at this time was 200 ° C. The disk was spun at 25000 rpm, and the
Nylon 12 (melting point: 175 ° C.) having a relative viscosity of 5% meta-cresol solution of 1.2 was heated at 350 ° C., and a stock solution was supplied at 2.5 kg / hr. The product obtained at this time was a brown powder having an average diameter of 18 μm.

[0017]

Comparative Example 4 As shown in FIG. 2, the ambient temperature was set at 140 ° C., and the hot air for heating the disk was set at 350 ° C. The measured temperature of the disk at this time was 200 ° C. The disk was spun at 25000 rpm, and the
A stock solution of nylon 12 (melting point: 178 ° C.) having a relative viscosity of 5% meta-cresol solution of 1.4 heated to 350 ° C. was supplied at 2.5 kg / hr. The product obtained at this time was a brown floc.

[0018]

As described above, according to the present invention, a resin powder close to a true sphere having a smaller particle size than the conventional method can be easily produced without thermal deterioration. In addition, a resin material having a relatively high melt viscosity can be used.

[Brief description of the drawings]

FIG. 1 is a diagram of an atomizer disk with an induction heating coil according to the present invention attached thereto.

FIG. 2 is a diagram of an atomizer disk when heating with hot air according to a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc 2 Coil 3 Radiation thermometer 4 High frequency generator 5 Temperature controller 6 Temperature indicator 7 Undiluted solution 8 Hot air (for maintaining atmospheric temperature) 9 Cold air 10 Hot air (for disk heating) 11 Insulation material

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B29B 9/10 C08J 3/12

Claims (2)

(57) [Claims] 1. A spray cooling granulation method, wherein a rotary disk is heated by induction heating in spray cooling and granulating a molten resin by a disk atomizing method. 2. A spray cooling and granulating apparatus for molten resin by a disk atomization method, wherein a coil is installed near a rotating disk made of a magnetic material, a high frequency generator is connected to the coil, and the rotating disk is induction-heated. A resin granulating apparatus characterized by the above-mentioned.