JP3165184B2 - Method for producing spherical fine powder of amorphous nylon resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to a method for producing spherical powder of amorphous (transparent) nylon resin.

[0002]

2. Description of the Related Art Various methods for producing a nylon resin powder or a nylon resin-coated powder have been proposed. However, in order to obtain a fine spherical powder, in addition to a combination of solvents, it is necessary to prevent particle precipitation conditions and prevent reagglomeration. It is necessary to satisfy the following condition.
Also, in the method for producing nylon fine particles, even if the conditions selected by small-scale experiments are applied to the operation of mass production equipment as they are, the production and survival conditions of spherical fine particles are maintained by the heat capacity of the container or natural convection of the solution. It is impossible.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method for industrially and economically producing amorphous nylon. In order to obtain nylon particles from a nylon resin solution, not only a solvent but also a medium for dispersing the produced particles is required, and therefore, it is necessary to prepare a mixed solvent. Further, in order to obtain spherical particles, it is necessary to satisfy a condition that the generated particles are suspended in the liquid, and therefore, it is preferable that the specific gravity of the mixed solvent is substantially equal to the specific gravity of the generated nylon particles. . In addition, the solvent must have a boiling point of 150 ° C. or higher to dissolve the nylon resin. Furthermore, in the cooling step of generating particles, a conventional cooling means simultaneously forms a nylon resin film on the bottom of the tank, which not only significantly lowers the particle generation efficiency, but also blocks the liquid discharge port.

[0004]

According to the present invention, dimethylacetamide or morpholine is selected as a solvent.
A mixed solvent in which 100 parts by volume of ethylene glycol is blended as a dispersion medium with respect to 80 parts by volume. Further, in order to lower the solution temperature in the particle precipitation step from above, a multi-stage jacket is employed, and a cooling medium is sequentially supplied from the upper jacket to the lower jacket to prevent a nylon resin film from being formed in the tank. Further, by pouring a solution having the same composition as the mixed solvent at a temperature immediately before the particles are precipitated, the time until the step of separating the produced particles is shortened.

According to the present invention, 5 to 20 parts by weight of an amorphous nylon resin is dissolved at a temperature of about 160 ° C. in 100 parts by volume of the mixed solvent in a stirring and dissolving tank provided with the multistage jacket. . p. m. Lower or lower the speed below to allow water to flow through only the upper jacket of the multi-stage jacket for a predetermined time, further flow through the middle jacket for a predetermined time, and finally flow through the lower jacket to finally bring the liquid temperature to about 60 The solution is introduced into a filtration device at a temperature of not more than 0 ° C. to separate the produced particles and collect the solvent. Thereafter, the particles are dried by a known vacuum dryer and the residual solvent is collected and reused.

Further, 5 to 20 parts by weight of the resin is dissolved in 50 parts by volume of the mixed solvent and cooled by the same cooling method as described above to reduce the liquid temperature to about 120 ° C. or lower and to be the same as the solvent used before particle deposition. The solvent of the composition is 30 to 1 of the above solvent amount.
It is intended to uniformly disperse the particles by injecting them in a short period of time by a volume of 00% to shorten the cooling time of the solution. If the concentration of the nylon resin is high, the produced particle diameter increases, so the upper limit is about 4
0%. In addition, when the amount of the solvent to be injected is large, the cooling time is shortened as the amount is increased. However, there is a disadvantage that it takes time to recover the filtrate.

[0007]

Example 1 A mixed solvent prepared by mixing 600 L of ethylene glycol and 400 L of morpholine in a 3-stage jacketed stirring tank (capacity: 2000 L) 1 as shown in FIG.
Furthermore, nylon 12 (Mitsubishi Chemical Corporation "Grilamide T"
R-55) 50 kg was charged, and the air in the tank was replaced with N ₂ gas.
p. m. To dissolve the nylon pellets. The heating was stopped and the stirring speed was 25 r. p. m. After opening the valve 2A of the upper jacket 2 and passing cooling water (temperature 18 ° C.) for 1 hour, then opening the valve 3A of the middle jacket 3 and passing cooling water for 30 minutes, the lower jacket 4 Valve 4
A was opened and water was passed for 30 minutes. Thereby, the temperature of the solution in the tank became about 110 ° C. If the water is continuously passed through all the jackets for another 2 hours, the liquid temperature will be about 60 ° C., during which the nylon fine particles will float in the liquid. The bottom discharge valve 5 is opened and introduced into a filter press (not shown) to separate the particles. In this step, about 70% of the mixed solvent is recovered. Put the filtered particles in a vacuum stir drier with a condenser for about 4
Dry at 0 to 80 ° C and 5 to 10 torr for 4 hours.
In this process, about 27% of the solvent was recovered in the receiver tank through the condenser (97% in total). The particle size distribution of the obtained particles is as shown in FIG.
The average particle size of 0% was 6.5 μm. The vertical axis of the graph is the cumulative%. (Use "Laser Micron Sizer 7000S" manufactured by Seishin Enterprise Co., Ltd.) The recovered solvent is reused as it is. In the cooling step, the stirring may be stopped.

[0008]

Example 2 Nylon 6 ("Novamid X21", Mitsubishi Chemical Corporation) 80 kg instead of nylon 12 in Example 1
Was added to form a high-concentration solution, and when the temperature of the solution reached about 120 ° C., 500 L of a mixed solvent (normal temperature) having the same composition was injected within about 5 minutes. The liquid temperature reached 80 ° C., and thereafter, the cooling was continued to about 60 ° C., and thereafter the same operation as in Example 1 was performed to obtain a powder. According to this method, the time required until the filtration step can be reduced by 1 hour to 1 hour and 30 minutes. Maximum particle size of generated particles is 5
Although it was 5 μm, the distribution was almost the same as in FIG.
Since the recovered solvent has the same composition as the mixed solvent used, it can be reused.

[0009]

Example 3 A similar product was obtained under the same conditions even when morpholine of Example 1 was changed to dimethylacetamide.

[0010]

According to the present invention, ultrafine spherical particles which can be used as a cosmetic or paint compounding agent can be produced in large quantities from amorphous nylon pellets. Furthermore, since the liquid is cooled from the top in the cooling step, it is possible to prevent the nylon resin film from adhering to the bottom of the tank, to increase the particle generation efficiency, and to reuse the recovered solvent, which is economical.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a dissolution tank used in the present invention.

FIG. 2 is a graph showing a particle size distribution according to Example 1.

[Explanation of symbols]

 2 is the upper jacket 3 is the middle jacket 4 is the lower jacket 5 is the discharge valve

Claims (2)

(57) [Claims] An amorphous nylon resin (5 to 2) is placed in a heating and stirring dissolution tank provided with a multistage jacket divided vertically.
0 parts by weight and 100 parts by volume of a mixed solvent composed of 10 to 80 parts by volume of morpholine or dimethylacetamide with respect to 100 parts by volume of ethylene glycol were added and dissolved by heating. Then, cooling water was passed through the upper jacket of the multi-stage jacket. And producing a spherical fine powder of an amorphous nylon resin, wherein the solution is cooled down sequentially from above by lowering or stopping the stirring speed and the solution temperature is reduced to 60 ° C. or lower. 2. An amorphous nylon resin 5 to 2 is placed in a heating-stirring / dissolving tank provided with a multistage jacket divided vertically.
0 parts by weight and 50 parts by volume of a mixed solvent composed of 10 to 80 parts by volume of morpholine or dimethylacetamide with respect to 100 parts by volume of ethylene glycol are dissolved by heating, and then cooling water is passed through the upper jacket of the multistage jacket. And the stirring speed is reduced or stopped, and the solution is cooled down sequentially from above.
When the temperature is 20 ° C. or less and no particles are formed, a solution having the same composition as the mixed solvent used is used in an amount of 30 to 10 with respect to the amount of the solvent.
A process for producing spherical fine powder of amorphous nylon resin, characterized in that a 0% volume is charged and the solution temperature is adjusted to 60 ° C. or lower to separate product particles.