JPS63189222A - Method for extruding thermoplastic compound - Google Patents

Abstract

PURPOSE:To obtain a mechanism to prevent particles from adhering to one another and keep them in separate state, and a mechanism to feed them to an extruder at a constant rate by a method wherein high temperature granular material, which is discharged from a high speed fluid mixer, is held in a drum type rotary surge tank and kept at the predetermined temperature. CONSTITUTION:When a mixture of solid dust and thermoplastic resin is agitated with a high speed fluid mixer 1 under the state that heat is supplied from outside and the peripheral speed of agitating blades is set to be 35-40 m/sec, the temperature of the mixture reaches a temperature higher than the melting point of the resin by 20-50 deg.C, resulting in obtaining granular material produced by adhering solid dust all around resin particles. After that, the granular material is discharged in a drum type rotary surge tank 3. The granular material is lifted along the wall of the rotating drum and falls by its own weight, parting from the wall when lifted to some extent. By repeating the above-mentioned action, the granular material will be kept in loosely ground state at all times, resulting preventing the particles from adhering to one another.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for extruding a thermoplastic resin compound containing solid fine powders such as inorganic fillers, organic fillers, and pigments. This invention relates to a method for extruding thermoplastic resin compounds used in extrusion molding, injection molding, blow molding, etc.

[Conventional technology]

Thermoplastic resins containing inorganic or organic fillers are widely used in the synthetic resin molding industry today because their rigidity and heat resistance can be improved at relatively low cost.

Conventionally, methods using extruders, mixing rolls, Banbury mixers, kneaders, etc. have been known as methods for blending these solid fine powders into all-thermoplastic resins, and after melt-kneading using these methods, molding machines It was granulated into a form that was easy to mold and supplied to the molder. Therefore, the conventional molding method has been to perform extrusion molding or injection molding using a filler type pellet.

[Problem that the invention seeks to solve]

The purpose of the present invention is to omit the granulation process in the extrusion molding of thermoplastic resin compounds containing solid fine powders such as inorganic fillers, organic fillers, and pigments, and to produce compounds mixed in a mixer.
The present invention provides a method for obtaining a molded product by directly charging the land into an extruder while maintaining the land at a temperature above its melting point.

The compound discharged from the mixer is heated above its melting point, so if it is held as it is, the molten particles will stick together and form a large molten mass, making it difficult to quantitatively feed it to the extruder. becomes.

The problem to be solved by the present invention is to provide a mechanism for holding the compound heated above its melting point while preventing it from sticking together, and a mechanism for quantitatively feeding the compound to an extruder.

Measures to solve problem C] In general, when mixing solid fine powder and thermoplastic resin in a batch type high-speed flow mixer, if heated above the melting point of the resin, solid fine powder would adhere around the molten resin. A granular compound is obtained. In the conventional technology, this is transferred to a cooling mixer and cooled to room temperature to solidify it. The solid particles thus produced generally have quite uneven particle sizes, and must be further crushed in a crusher to adjust the particle size before being fed to an extruder and molded.

However, in the above method, the compound that has been heated above its melting point must be cooled and then heated and melted again for molding, which is wasteful in terms of energy. The most effective method in terms of energy is to directly introduce the material heated above its melting point into an extruder and mold it without cooling it completely. However, when using a batch type high-flow type mixer, the mixer is a batch type and the extruder is a continuous type, so the molten compound is held between the mixer and the extruder for a certain period of time, and then sent out quantitatively. is necessary. The above-mentioned "molten compound" refers in a general sense to a state in which the compound is completely melted and does not look like it was extruded from an extruder, but looks like granules as a whole at first glance. This state varies depending on the amount of filler blended and the particle size of the thermoplastic resin, but in general, in the case of crystalline polymers, when the temperature range is 20 to 50°C higher than the melting point, the filler is formed around the thermoplastic resin particles. A adherent granular mixture is obtained.

If the temperature is further increased or shear is applied to a certain level, the granules will be kneaded and grow into a large block, making subsequent handling extremely difficult.

As a result of extensive research, the inventors of the present invention have found that by holding the high-temperature granules discharged from a high-speed fluid mixer in a drum-shaped rotating surge tank, and maintaining a predetermined temperature, the particles will separate from each other. It has been found that the state when discharged from the mixer can be maintained without sticking together and forming large molten lumps. When this rotating surge tank is tilted, the contents are gradually sent forward as it rotates. Also, if it is used continuously, there is a risk that molten matter will adhere to the inner surface of the drum and gradually grow like cholesterol in blood vessels, so this is to prevent this, and to turn the contents back. It is necessary to install a baffle plate. A rotary surge tank alone is sufficient for quantitatively feeding the extruder, but if particularly precise feed is required, a single or twin screw feeder may be used in advance to feed the extruder.

That is, in the method of extruding a thermoplastic resin compound of the present invention, a mixture of a solid fine powder and a thermoplastic resin is first heated in a high-speed flow type mixer while supplying heat from the outside at a circumferential speed of a stirring blade of 35.
When the mixture is stirred at a speed of ~40 m/sec, the temperature of the mixture reaches a temperature 20 to 50° C. higher than the melting point in several tens of minutes, and granules in which fine solid powder is attached around the resin particles are obtained. The granulate is then discharged into a drum-shaped rotating surge tank. Since the granules are heated above their melting point, if they are held stationary, the melted particles will stick together and form a large molten mass, making it difficult to cut out quantitatively, so they are constantly stirred. There is a need. Since the granules have an extremely high viscosity, a stirrer using a normal stirring blade would place a very large load on the stirring blade.
Stirring and mixing itself is not performed uniformly, and kneading occurs due to local shear stress near the stirring blades, which is undesirable because it promotes adhesion of particles.

If a rotating drum is used, the granules are lifted upwardly along the walls of the rotating drum until a certain point where they fall away from the walls under their own weight. By repeating this action, the granules are always kept in a mildly crushed state, thereby preventing particles from sticking together. Therefore, the rotational speed of the drum is relatively slow, 1 rpm or more, 3 rpm or more.
0 rpm or less, and 5 to 10 rpm.

If the rotation speed is too slow, as mentioned above, the crushing frequency is too low and there is a risk of mutual adhesion, while if it is too fast, the contents will remain stuck to the wall due to centrifugal force, making it necessary. No crushing action occurs.

The capacity of the drum should be such that it can hold about 2 to 5 times the amount of the mixture for one patch discharged from the mixer. Further, if the inner diameter of the drum is too small, it will not function as intended, so it is not particularly specified, but it is necessary to have a diameter of 300 m or more. The drum must be insulated to prevent the contents from dropping in temperature. It can also be heated from the outside if necessary.

The drum has an inclination in the axial direction because it must gradually feed the contents forward to the extruder or scree feeder while rotating. It is preferable to have a structure in which the inclination angle can be adjusted within the range of 5° to 30° so that the residence time of the contents can be adjusted. When operated continuously, the contents adhere to and grow on the inner wall of the drum, so it is necessary to provide a baffle plate to scrape this off. The structure of the baffle plate is preferably a spiral ribbon so that it can scrape off deposits on the inner wall and at the same time serve as a turning effect and a feeding effect on the contents.

The solid fine powders used in the present invention include talc, mica, calcium carbonate, graphite, titanium dioxide, potassium titanate, clay, silica, alumina, wollastonite,
Inorganic fillers such as glass powder, organic fillers such as cellulose, waste paper, fir cotton, silk, linen, synthetic fibers, and pigments.Also, the thermoplastic resin used in the present invention can be used in either powder or granule form. Examples of thermoplastic resins include polyethylene, polypropylene, polyvinyl chloride, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polybutene nylon,
Most of the materials commonly used in the molding field can be applied. The present invention will be explained in detail below using examples, but the scope of claims of the present invention is not limited thereto.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1゜Polyglobilay (MFR=0.5 g/I 0m1
n, trade name Sho Aroma-8A510) 50% by weight
, mixture 2 consisting of 50% by weight of talc (average particle size 8μ)
100% capacity in a tank heated to an external heating temperature of 160°C
The mixture was poured into a high-speed fluid mixer (suit saw mixer manufactured by Kawata Co., Ltd.) for 15 minutes at a circumferential speed of the stirring blade of 38 m/see, and when the temperature of the mixture reached 180 tl, it was immediately placed at the bottom of the mixer. It was discharged into the installed rotating surge tank. The rotating drum has an inner diameter of 500 mm and a length of 1,50 mm.
Con-ground 'tl-15 was rotated at 0 m with an inclination angle of 100 and a rotational speed of 1° rpm and discharged from the mixer.
After holding for a minute, the next patch was discharged from the mixer into a rotating drum. This operation was repeated two more times until the amount of compound in the rotating drum was 100 kg.

The rotary surge tank was fed a constant amount to a single screw extruder with a diameter of 65 mm at a discharge rate of 100 kg/hr. Hola i<? of 65mφ single screw extruder -The temperature of the compound at the mouth is 170
℃, and a temperature drop of about 10℃ was observed immediately after being discharged from the mixer.

The cylinder temperature of the extruder is set at 230°C, and the polypropylene resin containing 50% by weight of talc extruded from a T-guy with a lip width of 800cm at a resin temperature of 240°C has a width of 700m.
5+, and was shaped into a cod sheet with a thickness of 0.4. As a result of continuous operation for 10 hours, the compound was maintained in the rotating drum at all times, and stable operation was possible with no particles adhering to each other.

[Brief explanation of the drawing]

DESCRIPTION OF SYMBOLS 1...High-speed flow type mixer, 2...Mixer outlet, 3...Rotary type surnotator/return, 4...Baffle plate, 5...
... Extruder hopper, 6... Extruder. Figure 1v + Plastic tangle compound extrusion confinement procedure Amendment (method) % formula % 1. Indication of the case Patent Application No. 20562 of 1988 2. Name of the invention Method for extruding thermoplastic resin compound 3. Make the amendment Relationship with the Patent Case Address of Patent Applicant 2-10-12 Shiba Daimon, Minato-ku, Tokyo Name (2
00) Showa Denko Co., Ltd. Representative Village 1) - 4, Agent (Postal code 105) Residence Shiba Daimon 2-chome, Minato-ku, Tokyo! 0fi No. 12 5. Date of amendment order: April 28, 1985 (shipment date) 6. "Brief explanation of drawings" column of the specification subject to amendment. 7. Contents of amendment (1) Page 11 of the specification, between lines 2 and 3: 1 FIG. 1 is a schematic sectional view of an example of a thermoplastic resin compound extrusion device used in the present invention. ” is inserted.

Claims (3)

[Claims] (1) A mixture of solid fine powder and thermoplastic resin powder is heated in a batch-type high-speed flow mixer while stirring to a temperature above the melting point of the resin while supplying heat from the outside. Granules with the solid fine powder adhered to the surface of the plastic resin powder are formed, and then the granules are kept at a temperature higher than the melting point of the thermoplastic resin and fused together through a rotary surge tank. A method for extruding a thermoplastic resin compound, characterized in that a desired extrusion molded product is obtained by quantitatively feeding a thermoplastic resin compound to an extruder while preventing the above. (2) A certain amount of the thermoplastic resin discharged from the batch type high-flow mixer (1) is heated to a temperature higher than the melting point, and the granules are transferred to an inclined rotating drum-type surge tank equipped with a baffle plate (4). 3), and the thermoplastic resin according to claim 1, wherein the granulated material is slowly fed forward and quantitatively supplied to the extruder (6) while preventing mutual adhesion. Compound extrusion method. (3) The thermoplastic resin compound according to claim 2, wherein the rotation speed of the inclined rotating drum is 1 to 30 rpm, and the inclination angle of the drum is 5 to 30 degrees with respect to the horizontal. Extrusion method.