JP2977062B2 - Method for producing powder with improved dusting properties - 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 producing powder having significantly improved dusting properties. More specifically, the present invention relates to a method for efficiently obtaining a powder having significantly improved dusting properties in producing a powder by a spray drying method.

[0002]

2. Description of the Related Art In general, a solid powder has a feature that it is extremely apt to generate dust when handled because of its fine shape. Although the degree of dust generation varies depending on the shape of the powder, for example, the specific gravity of the particle diameter, in the case of unprocessed fine powder having a particle diameter of 200 μm or less, which is generally called a powder, dust generation of the powder during handling is avoided. Absent. In particular, in recent years, there has been a demand for the establishment of an efficient production technique for powders that are less likely to cause dust from the viewpoint of improving the working environment and protecting the environment.

Heretofore, in order to improve the dusting properties of these fine powders, (1) a large amount of a high specific gravity additive is added to increase the specific gravity of the dry powder, or (2) a moisturizer or a binder is used. Operations such as secondary coagulation of the particles and (3) mixing of the powder and the dust-preventing agent in a compounding machine have been performed.

In the method (1), for example, a relatively high specific gravity inorganic salt such as sodium sulfate salt is added before drying to increase the specific gravity of the dried powder so as to suppress dust generation. It is an attempt. However, in this method, there are many restrictions on the compounding agents that can be used in view of the quality of the target powder, and the dust generation improving effect is relatively small.

As the method (2), as shown in an example of fluidized bed granulation, a caking substance such as CMC, HE
This is an attempt to reconstitute primary particle powders once dried through polymer adhesive materials such as C and PVA, to increase the apparent particle diameter, and to suppress dust generation. However, the powder obtained by this method has a high porosity, a high bulk, a complicated shape, and a disadvantage that the fluidity peculiar to the powder is impaired.

The method (3) is a method in which the powder once dried and a dust-preventing agent are mixed in a compounding machine. The powder obtained by this method certainly improves dusting properties considerably,
This requires two steps, such as drying the powder once, taking it out, and then putting it into a compounding machine.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have sought to improve the above drawbacks and to produce powder with improved dusting properties at the time of powder production with simple and easy operation. The present invention has been completed. According to this method, it is possible to economically and efficiently produce a powder having a desired particle size and significantly improved dusting properties without changing the shape of the powder.

[0008]

According to the present invention, when a powder is produced by spray-drying a liquid (liquid product), dust generation is a non-volatile or non-volatile liquid having a boiling point of 80 ° C. or more. By coating the agent on the surface of the sprayed droplet of the liquid containing the substance to be dried immediately before drying, and then immediately drying the droplets with hot air, a powder with significantly improved dusting properties can be obtained. .

The liquid containing a substance to be dried (hereinafter referred to as a liquid to be dried) used in the present invention has completely dissolved a solute.
In addition to the true solution, any substance may be used as long as it is a suspended substance or a mixture of the suspended substance and the true solution, which leaves a solid component after drying. For example, the substance to be dried includes dyes, foods, industrial chemicals, and the like, but is not limited thereto. As the solvent of the liquid to be dried, an organic solvent or a mixture thereof can be used in addition to water.

The anti-dusting agent used in the present invention includes:
Any non-volatile or non-volatile liquid having a boiling point of 80 ° C. or higher, preferably 100 ° C. or higher may be selected.
For example, dioctyl phthalate, dibutyl phthalate,
Liquids such as liquid paraffin, mineral oil, vegetable oil, higher alcohols, polyhydric alcohols, sulfated oils, fats, higher fatty acids, polyoxyalkylene-type nonionic surfactants, and lecithin are preferred. The amount of the dust generating agent used is usually 0.1 to 5% by weight, preferably 0.2 to 2% by weight, based on the dry powder.

In the present invention, as a method for coating a dust-preventing agent, which is a non-volatile or non-volatile liquid having a boiling point of 80 ° C. or more, on the surface of spray droplets immediately before drying, for example, a rotary disk spray dryer Of simultaneously dropping the liquid to be dried and the dust preventive agent on the disc 1 (FIG. 1)
A method of injecting the above-mentioned dust-preventing agent from around the spray outlet of the nozzle 10 of the nozzle-type spray-dryer (supply cup 9 for injecting the dust-preventing agent) (FIG. 2), or a sprayed droplet just before drying A method of spraying an anti-dusting agent from one or a plurality of individual nozzles 17 and 18 (FIG. 3) can be selected.
Generally, the method according to FIG. 1 or FIG. 2 has less scattering of the dust generating agent itself and can be used more effectively than the method according to FIG.

The droplet particles coated with the dust-preventing agent, which is a non-volatile or non-volatile liquid having a boiling point of 80 ° C. or higher, are subsequently brought into contact with hot air in a drying tower to thereby form particles inside the particles. The solvent is evaporated to dryness, and the remaining dry particles remain in a coating state and become powder, and are taken out from a dry powder outlet 2 or 3 in FIG. 1 by a collector such as a cyclone.

According to the present invention, not only the drying step and the dust prevention step are performed simultaneously and continuously and efficiently, but also the amount of the dust prevention agent used is small and a remarkable dust generation suppression effect is exhibited. It has the feature that it is done. Also, the degree of dust generation can be easily and continuously controlled only by changing the amount of the dust generation inhibitor.

[0014]

EXAMPLES The present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. Example 1 Disperse Dye Kayaron Polyester Navable-2G-SF200 (manufactured by Nippon Kayaku) finely dispersed to an average particle size of 1 μm
1000 parts of an aqueous suspension in which 350 parts were dispersed and dissolved were heated at a hot air inlet temperature of 130 ° C. by the rotary disk type spray dryer of FIG.
Drying was performed at an outlet (powder outlet) temperature of 75 ° C. At this time, as shown in FIG. 1, in addition to the aqueous suspension of the dye, liquid paraffin of 0.5% by weight with respect to the dry dye was simultaneously dropped continuously on the rotating disk 1 with a metering pump, and spray drying was performed. Was. The dried powder dye collected from the cyclone after the spray drying had an average particle size of 80 μm, and was determined to be hardly dusting (quaternary) powder in the dusting test test.

In the dusting test, a funnel having a diameter of 2 cm and a height of 20 cm is placed in, for example, a cylindrical container 24 having a diameter of 8 cm and a height of 30 cm as shown in FIG. A 4 cm diameter filter paper 25 moistened with a slice of water was attached. 10g of dye powder to be tested on the triangular pyramid of the funnel
Was slowly shaken down over 1 minute and allowed to fall to the bottom in the container. The dust that flew up at this time was collected on a filter paper, and the filter paper was taken out 3 minutes after all the dye had fallen. At this time, the degree of adhesion of dust to the filter paper was visually ranked 1 to 5. Class 5 Filter paper is not contaminated at all (no dust is generated) Class 4 Filter paper is hardly contaminated (no dust is generated) Class 3 Filter paper is slightly contaminated (a little dust is generated) Class 2 Filter paper is considerably contaminated (Equivalent dust is generated.) Class 1 Filter paper is significantly contaminated (Emits significant dust.)

Comparative Example 1 In Example 1, the powder dye obtained by spray-drying only the aqueous suspension of the dye without dripping any liquid paraffin on the rotating disk 1 has the same particle size as in Example 1. Although it was 80 μm, dust was remarkably generated, and the dust generating property was determined to be class 1.

Comparative Example 2 Instead of simultaneously dropping liquid paraffin onto the rotating disk 1 in Example 1, 0.5% of liquid halaffin was similarly added to the dye supply pipe 5 5 m before the disk and spray-dried. . The obtained powder dye had remarkably higher dusting property than the powder dye obtained in Example 1, and was judged as secondary.

Example 2 Basic water-soluble dye K was prepared by using the nozzle type spray drier of FIG.
AC Yellow 3RL (manufactured by Nippon Kayaku Co., Ltd.) dissolved 100 parts of an aqueous solution in an inlet temperature of 150 ° C. and an outlet temperature of 80 parts.
The composition was spray-dried at 110 ° C. and a spray pressure of 110 kg / cm ² . At that time, using a metering pump from the periphery of the spray port of the spray nozzle 10 (supply cup for injecting the dust-preventing agent), the dry dye was used to perform 1.
Spray drying was continued while quantitatively injecting 0% by weight of dioctyl phthalate. Thus, the dry powder outlet 1
The dry powder dyes obtained from 3, 14 had an average particle size of 50 μm.
m, but the dusting property was class 5.

Comparative Example 3 In Example 2, the injection position of the dust-preventing agent was changed, and the same amount of dioctyl phthalate was injected under high pressure into the supply pipe 12 of the dye solution 30 cm before the nozzle spray port. In the same manner, the powder dye obtained by spray-drying has a judgment value of 1 which is extremely easy to generate dust.
Grade powder.

Example 3 In Example 2, the same amount of silicone oil was added in place of dioctyl phthalate, and spray drying was performed in the same manner. The obtained powder dye was determined to be a quaternary powder that hardly generates dust.

Example 4 1000 parts of a water slurry in which 0.2 part of Food Color Yellow No. 4 and 100 parts of flour were dispersed was dried at a inlet temperature of 150 ° C. and an outlet temperature of 80 ° C. using the rotating disk type spray dryer shown in FIG. did. At this time, in addition to the flour slurry, 0.3 parts of edible oil was simultaneously dropped continuously with a metering pump on the rotating disk 1 as shown in FIG. 1 and spray-dried. The dried flour obtained after the spray drying was a quaternary powder that hardly dusted in the dusting test.

Comparative Example 4 In Example 4, instead of simultaneously dropping the edible oil on the rotating disk 1, the same amount of edible oil was added to the flour slurry supply pipe 5 3 m before the disk and spray-dried. did. The obtained flour was judged to be a second-class powder having significantly higher dusting properties than the flour obtained in Example 4.

Example 5 1000 parts of a 30% aqueous suspension of calcium carbonate finely dispersed to a particle diameter of 1 μm was obtained by using a nozzle type spray dryer of FIG. 3 at an inlet temperature of 140 ° C., an outlet temperature of 100 ° C., and a spray pressure of 80 kg. / cm ²
And spray dried. At this time, as shown in FIG. 3, three parts of machine oil (boiling point: 250 ° C.) are simultaneously sprayed from another spray nozzles 17 and 18 onto the sprayed droplets immediately before drying, and the machine oil is coated on the droplets. Let dry. The resulting calcium carbonate fine powder was a fifth-grade powder that did not generate dust at all.

Comparative Example 5 In Example 5, the injection position of the machine oil was changed to the supply pipe 16 for the calcium carbonate suspension, and the amount of the machine oil was further increased to 5 parts. The dustability of the powder was lower than that of Example 5.

[0025]

According to the present invention, a technique has been established for efficiently obtaining powder with improved dusting properties simultaneously with drying.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rotary disk type spray dryer.

FIG. 2 is a sectional view of a nozzle type spray dryer.

FIG. 3 is a sectional view of a nozzle type spray dryer.

FIG. 4 is a sectional view of an apparatus for measuring dust.

[Explanation of symbols]

1. Rotating disk 2.3, 13, 14, 21, 22 Dry powder outlet (hot air outlet) 4.11, 17, 18 Dust prevention agent supply pipe 5.12, 16 Liquid to be dried supply pipe 6. Hot air inlet 7. Motor 8.15, 20 Spray dryer main body 9. Supply cup for dust prevention agent injection 10.19 spray nozzle 23. Funnel 24. Cylindrical container 25. Wet filter paper

Claims (2)

(57) [Claims] An anti-dusting agent, which is a non-volatile or non-volatile liquid having a boiling point of 80 ° C. or higher, is coated on the surface of a liquid droplet containing a substance to be dried immediately before drying. A method for producing a powder with improved dusting characteristics, characterized by drying droplets with hot air. 2. The method according to claim 1, wherein the substance to be dried is a dye.