JPS59214631A - Twin screw extruder - Google Patents

Abstract

PURPOSE:To obtain a twin screw extruder capable of drying, melting and extruding undried thermoplastic resin chips by providing slits through which water and vapor are discharged on the lower part of a cylinder barrel where the feeding section of screw is positioned. CONSTITUTION:A multiple stage (three stages in Fig.) consisting of a feed section 6a, a rotor section 6b and a slot section 6c is provided from the base to the front, and a final stage consisting of a discharge screw 6d is provided to the front of the multiple stage for each of two screws 6 and 6'. In a twin screw extruder in which the two screws 6 and 6' are engaged with each other and turned inversely, slits 5 for dewatering are provided to the lower part of a cylinder barrel 1 where the feeding section 6a of the first stage (the first and second stages in Fig.) is positioned. Also, a material supply port 2 is provided in the upper part of the cylinder barrel 1 where the feeding section 6a of the first stage is positioned, and vent holes 4 are provided in the upper part of the cylinder barrel 1 where the feeding section 6a of the other stages is positioned.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to thermoplastic resins such as ABS, MBS, etc.
This invention relates to a twin-screw extruder used for dehydration, extrusion, and granulation of rubbery polymers such as R, IIR, and BR.

Polymers such as thermoplastic resins and rubbers are in the form of powder or crumb and contain a large amount of water when they are manufactured. Conventionally, such hydrous polymers were dehydrated by hot air drying. This consumes a large amount of energy, and the polymer itself may deteriorate due to being exposed to high temperatures for a long period of time. Further, even if an attempt was made to dehydrate the product using an extruder, there were problems such as insufficient biting into the screw of the extruder, insufficient extrusion amount, and insufficient deaeration due to the high water content.

In place of conventional hot air drying, the present invention has a cylinder barrel equipped with a slit section for discharging moisture and steam, thereby solving the problems caused by conventional extruders. By providing an extruder, the purpose is to save energy consumption for dehydration of hydrous polymers.

A twin screw extruder according to the present invention will be explained with reference to the drawings.

FIGS. 1 and 2 show a four-stage interlocking extruder, and FIG. 3 shows a three-stage interlocking extruder with two shafts rotating in different directions.

Reference numeral 1 denotes a cylinder barrel, at the base end of which a material supply port 2 is provided for supplying powdered or crumb-like water-containing polymer;
A discharge port 3 for molten polymer is provided at the tip. Reference numeral 4 denotes a vent hole for degassing provided in the cylinder barrel 1 of each stage after the second stage; 6'a and discharge screw part 6d.

6' It is provided at the location where d is located. 5 is a cylinder barrel 1 in which feed portions 6a and 6'a of the screw shaft, which will be described later, are located in the first stage and the second stage.
There is a slit in the lower part of the tank with a parallel gap provided for dehydration and steam removal, and it is connected to a drainage pump, etc. (not shown). Reference numerals 6 and 6' denote screw shafts inserted into the cylinder barrel 1 and driven to rotate in meshing states in opposite directions by a drive device (not shown). 6a, 6'a are screw shafts 6
, 6' are formed by threading flights 6IL', 6'a', and is a feed section for transporting the water-containing polymer supplied into the cylinder barrel 1 from the material supply port 2.
b, 6'b are rotors 6b', 6'b' in which two helical protrusions having relatively large forward and reverse lead angles are provided on the creu shafts 6, 6', and the cross section thereof is elliptical. is formed and is a rotor part that plasticizes the polymer and separates water, and 6 c and 6' c are the screw shafts 6
, 6' are formed with lands 6c', 6'c' having minute gaps with the inner circumferential surface of the cylinder barrel 1, and are slot portions for controlling the melting area of the polymer. 6d, 6'd are
7 lights 6 d', 6' on screw shafts 6, 6'
d' is a portion of the discharge screw that is formed with a thread and is the final stage for discharging the molten polymer.

The four-stage twin-screw extruder shown in Figure 1 consists of
In the stage, the screw shafts 6, 6' are connected to the feed sections 6a, 6'a, the rotor sections ab, crb, and the slot sections 6c, 6'e, and in the fourth stage, which is the final stage, the screw shafts 6, 6'6' is the discharge screw portion 6d, 6'd.

In addition, the three-stage twin-screw extruder shown in Fig.
In the stage, the screw shaft 6 has a feed portion 6a, a rotor portion 6b, and a slot portion 6c, and in the third stage, which is the final stage, the screw shaft 6 has a discharge screw portion 6d.

By connecting a granulation die to the discharge port 3 if necessary, this twin-screw extruder can be used as a dehydration and degassing granulation extruder.

Next, the effect will be explained.

The powdered or crumb-like water-containing polymer supplied to the material supply port 2 is forced forward inside the cylinder barrel 1 at the feed sections 6a, 6'a of the first stage, and the squeezed out water is passed through the slit section. 5. Water is drained outside the cylinder barrel.

In the rotor parts 6b, 6'b, the slot part 6c on the other side
.

Under the influence of 6'c, the polymer is plasticized, water is further separated, and the polymer is pumped to the second stage.

The polymer sent to the second stage mainly discharges steam through the slit section 5, and is deaerated through the vent hole 4, thereby reducing the effects of the rotor sections 6b, 6'b, and slot sections 6c, 6'e. It is received in the same way as the stage and pumped to the third stage. In the third stage, the polymer progresses to plasticization, moisture and volatile matter are degassed through the vent hole 4, and the polymer is subjected to the action of the rotor parts 6b, 6'b and slot parts 6c, 6'c. The completely melted polymer that is pressure-fed to the fourth stage is further degassed through the vent hole 4 and is discharged through the discharge port 3 by the action of the discharge screw portions 6d and 6'd.

The operation of the three-stage twin-screw extruder shown in FIG. 3 is substantially the same as in the case where the explanation of the third stage of the four-stage twin-screw extruder is omitted.

According to tests, hot air drying requires 0.5 kwhr/
When a water-containing polymer that required a specific energy of kt is processed to a similar dry state using the twin-screw extruder according to the present invention, the specific energy required for drying is 0.2 kwhr/kf, and 0.71 cwhr/kf. 0.31c for ky
A result of whr/ky was obtained.

In addition, since it is an intermeshing extruder with two shafts rotating in different directions, in the feed section of the first stage, powdered or crumb-like water-containing polymer is concentrated between the two screw shafts, and the polymer is not extracted from the slit section. There wasn't much.

The twin-screw extruder according to the present invention has a first extruder in which a feed section, a rotor section, and a slot section are formed in order toward the destination.
It has a stage, an intermediate stage connected to this, and a final stage connected to the intermediate stage to form a part of the discharge screw, and two screw shafts that mesh with each other and rotate in opposite directions are attached to the base end of the material. In a twin-screw extruder configured by inserting a supply port into a cylinder barrel having a discharge port formed at the tip thereof and a vent hole for degassing attached to the front side near each slot portion, at least the above-mentioned A slit for dewatering is provided at the bottom of the cylinder barrel where the feed section of the first stage is located.

Therefore, even if powdered or crumb-like polymer containing a large amount of water is directly supplied, the dehydrated and degassed molten polymer can be supplied without causing insufficient biting into the screw or insufficient extrusion amount. We were able to provide a twin-screw extruder that can obtain the desired results, and the energy required for drying could be reduced by more than half compared to the energy consumed by conventional hot air drying.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a four-stage twin-screw extrusion according to the present invention, FIG. 2 is a cross-sectional view taken along the line I[-I in FIG. 1, and FIG. It is a sectional view of a twin screw extruder. 1 Nijilinda barrel, 2: Material supply port, 3: Discharge port, 4
:Vent hole, 5 nislit part, 6, 6' niscrew shaft, 6a, 6'a: Feed part, 6 a', 6' a
': 7 light, jb, 6'b: o-yube,
6 b', 6'b': Rotor, 6c, 6'c double slot part, 6 c', 6'e': Land, 6
d, 6'd: Part of the discharge screw, 6 d', 6'
d': Flight.

Claims (1)

[Claims] l. It has a first stage in which a feed part, a rotor part, and a slot part are formed in sequence toward the destination, an intermediate stage connected to this, and a final stage connected to the intermediate stage and forming a part of a discharge screw. , two screw shafts that mesh with each other and rotate in opposite directions are formed with a material supply port at the base end and a discharge port at the tip, and vent holes for deaeration are provided on the forward side near each slot. A twin-screw extruder constructed by being inserted into an attached cylinder barrel, characterized in that a slit section for dehydration is provided at least at the bottom of the cylinder barrel where the feed section of the first stage is located. Extruder.