JPH07113063B2 - Resin fine powder manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is to dissolve a resin raw material such as polyethylene by heating and stirring it in a solvent, cool the resin solution obtained by the dissolution while stirring, and cool it. The present invention relates to a method for producing a resin fine powder in which the obtained resin slurry is vacuum dried while stirring.

[Conventional technology]

Conventionally, the melting and cooling steps have been performed by a high-speed agitation type first apparatus, and the vacuum drying step has been performed by a low-speed agitation type second apparatus.

As shown in FIG. 3, the first device is provided with a stirring blade (17) which is rotated at a high speed at the bottom of the container (16), and a heating fluid supply source (for a jacket (18) attached to the container (16) ( 19) and a cooling fluid supply source (20) are connected so that heating and stirring during melting and cooling while stirring can be performed.

The second device, as shown in FIG. 2, is a closed container (1).
A lifting / conveying screw (8) tilting with respect to the vertical center (P) is provided in the container so as to be rotatable at low speed around the vertical center (P), and a vacuum pump (13) is installed in the container (1). It is configured so that it can be connected and vacuum dried while stirring.

That is, the above-mentioned conventional technology is based on the technical idea that a fine resin powder can be obtained by stirring at a high speed in the steps of melting and cooling.
Since the equipment consumes a huge amount of power per processing amount, it is based on the technical idea that only the vacuum drying, which does not require high-speed agitation, is performed by the second equipment of the low-speed agitation type, which consumes less power. there were.

[Problems to be Solved by the Invention]

However, the use of two types of devices complicates the manufacturing process, requires a lot of labor and time for manufacturing, and has a drawback that the equipment cost is high.

Also, since the high-speed stirring type first device is used, the power cost is high, which is disadvantageous in terms of manufacturing cost.
Even if the stirring speed of the apparatus is increased, a fine resin powder of about 10 μm or less cannot be obtained, and the particle size and shape of the resin powder are uneven, resulting in a low product yield.

The object of the present invention is based on a novel technical idea that is completely different from the above-mentioned conventional idea, in a simple process, with a reduced number of steps and time, inexpensive equipment, sufficiently fine resin fine powder. The point is to establish a new and useful method for producing fine resin powder, which can be obtained in good yield.

[Means for Solving the Problems]

The characteristic means of the present invention is to heat and stir the resin raw material in a solvent to dissolve it, to stir and cool the resin solution obtained by the dissolution, and to vacuum dry the resin slurry obtained by the cooling while stirring. All are executed by the same device, and as the device, a lifting / conveying screw tilting with respect to the vertical center is provided in the closed container so as to be rotatable about the vertical center, and heating means is provided on the container. And a cooling means are additionally provided and a vacuum pump is connected, and the function and effect are as follows.

[Action]

In the production of resin fine powder by melting, cooling, and vacuum drying, we investigated what is the major factor that determines the particle size, and the stirring speed, which was conventionally thought to be important, has no significant meaning. It was found that the mixing ratio of the solvent with respect to is important, the average particle size is determined by the mixing ratio, and the average particle size decreases as the mixing ratio increases.

Based on the above new knowledge, melting, cooling, and vacuum drying are performed by a low-speed agitation type device that rotates the lifting and conveying screw that tilts as described above around the vertical center of the container that can heat, cool, and vacuum dry. After performing all the steps of and examining what kind of resin fine powder is actually obtained,
We were able to confirm the facts in (a) and (b) below.

(A) The particle size is uniform and the shape is spherical, so that the product yield can be sufficiently improved. For example, in the case of recovering a product having a particle size of 70 μm or less, the yield was as high as about 70 to 80% in the method of the present invention, while it was about 45 to 50% in the above-mentioned conventional technique.

(B) By increasing the mixing ratio of the solvent to the resin raw material, extremely fine resin fine powder having a particle size of about 10 μm or less, which could not be obtained by the above-mentioned prior art, was obtained. For example, when dissolving polyethylene pellets with trichlorethylene,
The mixing ratio of trichlorethylene to polyethylene
When the ratio was 1: 4, the average particle size was about 15 μm, when the mixing ratio was 1: 5, the average particle size was about 5 μm, and when the mixing ratio was further increased, the average particle size was 4 μm or less.

In addition, since melting, cooling and vacuum drying are performed in the same apparatus, the process can be simplified, the number of man-hours and time required for manufacturing can be sufficiently reduced, and the equipment cost can be significantly reduced.

Further, since only a low-speed agitation type device that consumes less power per processing amount is required, the power cost can be significantly reduced. By the way, the first device of the high-speed stirring type used in the above-mentioned prior art requires 37 kw of power for a throughput of 120 kg, whereas the low-speed stirring type device used in the method of the present invention requires an extremely small power of 7.5 kw for a throughput of 800 kg. I'm done.

〔The invention's effect〕

As a result, it has been possible to establish a very useful method for producing resin fine powder, which is capable of obtaining sufficiently fine resin fine powder in good yield, easily, efficiently and inexpensively.

〔Example〕

 Next, examples will be shown.

As shown in FIG. 1, the resin raw material and the solvent are put into a low-speed stirring type apparatus, and the resin raw material is heated and stirred in the solvent to be dissolved.

As the resin raw material, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl acetate, or any other suitable thermoplastic resin is used, for example, pellets having a diameter of about 2 to 3 mm are used.

The solvent is appropriately selected according to the resin raw material, and for example, trichloroethylene, perchlorethylene, carbon tetrachloride, tetrachloroethylene, trichloroethane, or any other suitable solvent is used. However, since perchlorethylene has a low boiling point, it is easy to collect, has no toxicity, and has a strong resin-dissolving power, which is optimal.

The mixing ratio of the solvent to the resin raw material is appropriately selected according to the desired particle size of the resin fine powder product and the kind of the resin raw material and the solvent, and the particle size of the resin fine powder product becomes smaller as the proportion of the solvent increases. For example, when polyethylene pellets are dissolved in trichloroethylene, the results are shown in the table below.

The heating temperature is appropriately selected depending on the type of resin raw material and solvent, and is generally about 65 to 120 ° C.

Next, the resin solution obtained by dissolution is cooled to about 20 ° C. while stirring, and the resin slurry obtained by the cooling is vacuum dried while stirring.

Further, the resin fine powder obtained by vacuum drying is separated and sorted to obtain a product having a desired particle size.

All of the melting, cooling and vacuum drying steps are carried out in the same apparatus, which will be described below with reference to FIG.

The container body (1a) and the lid body (1b) each having a substantially inverted conical shape form a hermetically sealed container (1) for accommodating a treatment object, and the treatment material inlet with an opening / closing lid (2) is provided on the lid body (1b). ), A shutter (4) that can be opened and closed by a fluid pressure cylinder (3)
A discharge port having is provided on the bottom side of the container body (1a).

An arm (5) rotatable about a longitudinal center (P) of the container (1), and an electric motor (6) and a speed reducer (7) for rotationally driving the arm (5) are attached to a lid (1b). , The screw (8) rotatably supported on the free end side of the arm (5) is tilted with respect to the longitudinal center (P),
Further, the screw (8) is arranged inside the container (1) so as to approach the container body (1a), and the arm (5) is internally provided with a driving means for rotating the screw (8) in accordance with the rotation of the arm (5). It is configured to pick up and convey the processed material along with its rotation.

A jacket (9) is attached to the container body (1a), and a lid (1
The jacket (10) is installed in b), the high temperature fluid source (14) and the low temperature fluid source (15) are connected to both jackets (9) and (10), and the on-off valves (V ₁ ) and (V ₂ ) are operated. And jacket (9), (1
0) and configured to supply hot fluid or cold fluid, the flow rate adjusting valve (V _3), (V ₄₎ in both the jacket (9), (1
It is configured so that the amount of fluid supplied to 0) can be set appropriately. Further, a dust collector (11), a condenser (12) and a vacuum pump (13) are connected to the container (1) to discharge the vapor in the container (1).

In short, in the melting step, the lifting and conveying screw (8) is rotated and revolved to stir the resin raw material and the solvent at a low speed, and the high temperature fluid is supplied to the jackets (9) and (10) to produce the resin raw material. And heat the solvent.

Then, in the cooling step, the resin solution is lifted and stirred at a low speed by the conveying screw (8), and the jacket (9),
A low temperature fluid is supplied to (10) to cool the resin solution.

Further, in the vacuum drying step, the resin slurry is lifted and stirred at a low speed with the screw (8) for conveyance, and the jacket (9),
The resin slurry is heated with (10) and the vacuum pump (1
3) is activated to vacuum dry the resin slurry, and then the shutter (4) is opened to collect the resin fine powder.

[Another embodiment]

 Next, another embodiment will be described.

The container (1) can be appropriately changed in structure, shape and the like.

The structure of the screw (8) can be changed to an intermittent wing structure or a double spiral structure, and a plurality of screws (8) may be provided.

Instead of the jackets (9) and (10), an appropriate heating structure such as an electric heater may be provided, and these heating structures are collectively referred to as heating means (9, 10, 14).

The cryogenic fluid source (15) may be tap water, a refrigerator, or any other suitable source, and therefore the means for cooling are collectively referred to as cooling means (9, 10, 15).

The inside of the container (1) may be degassed by the vacuum pump (13) before the melting step, or the inside of the container (1) may be depressurized at the beginning of the melting step.

The inside of the container (1) may be degassed by the vacuum pump (13) before the cooling step.

Water may be poured during the vacuum drying process to rapidly remove the solvent by azeotropic distillation.

The classification and selection step may be omitted.

The use of the resin fine powder is not limited, and it can be used, for example, as a FRP modifier, wax, putty material, cosmetics, and clay for teaching materials.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a flow sheet of the method of the present invention, FIG. 2 is a conceptual diagram of an apparatus used in the present invention and a conventional example, and FIG. 3 is a conceptual diagram of an apparatus used in a conventional example. (1) …… Container, (8) …… Lifting and conveying screw,
(9,10,14) …… Heating means, (9,10,15) …… Cooling means,
(13) …… Vacuum pump, (P) …… Centered vertically.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References Japanese Patent Publication Sho 61-12933 (JP, B2)

Claims (1)

[Claims] 1. A resin raw material is heated and stirred in a solvent to dissolve it,
A resin fine powder manufacturing method in which the resin solution obtained by the dissolution is cooled while stirring, and the resin slurry obtained by the cooling is vacuum dried while being stirred, and all the steps of the dissolution, cooling and vacuum drying are performed by the same apparatus. As a device, a lifting / conveying screw (8) tilting with respect to the vertical center (P) of the closed container (1) is rotatably driven around the vertical center (P). A method for producing fine resin powder, wherein the container (1) is provided with heating means (9,10,14) and cooling means (9,10,15) and a vacuum pump (13) is connected.