JPS6316249B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to dehydration, degassing, and production of thermoplastic resins such as ABS and MBS, and water-containing polymers (water content 20 to 70% by weight) such as rubber such as EPR, IIR, and BR. Regarding twin screw extruders used for granules.

Polymers such as thermoplastic resins and rubbers are in the form of powder or crumb in their manufactured state and contain a large amount of water (20 to 70% by weight). However, when the water content of the polymer exceeds 10% by weight,
It cannot be extruded using a conventional twin-screw extruder. Therefore,
Dehydration of such hydrous polymers has conventionally been carried out 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. Even when dewatering was attempted using an extruder, there were problems such as insufficient biting into the screw of the extruder, insufficient extrusion volume, and insufficient deaeration due to the high water content.

The present invention is a twin-screw extruder suitable for dehydration, degassing, and granulation, which solves the problems caused by conventional extruders by providing a slit section in the cylinder barrel to discharge moisture instead of conventional hot air drying. The aim is to save energy consumption for dehydration of hydrous polymers by providing

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. 1
is a cylinder barrel, the base end of which is provided with a material supply port 2 for supplying a water-containing polymer in the form of powder or crumb, and the distal end thereof is provided with a discharge port 3 for molten polymer. Reference numeral 4 denotes vent holes for degassing provided in the cylinder barrel 1 of each stage after the second stage, and feed portions 6a, 6a, 6c, 6'c of screw shafts 6, 6', which will be described later, are located near the slot portions 6c, 6'c of screw shafts 6, 6'.
6'a and the discharge screw portions 6d, 6'd are located. Reference numeral 5 denotes a slit portion consisting of a parallel gap provided mainly for dewatering at the lower part of the cylinder barrel 1 where 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. Connected to a drainage pump, etc. Reference numerals 6 and 6' denote screw shafts inserted into the cylinder barrel 1 and rotationally driven by a drive device (not shown) in mutually meshing directions in different directions. 6a, 6'a are formed by threading flights 6a', 6'a' on the screw shafts 6, 6', and transport the water-containing polymer supplied into the cylinder barrel 1 from the material supply port 2 forward. Feed section, 6
b, 6'b are rotors 6b', 6' in which the screw shafts 6, 6' are provided with two spiral protrusions having relatively large forward and reverse lead angles, and the cross section thereof is elliptical.
6c and 6'c are lands 6c' and 6'c, which have minute gaps with the inner peripheral surface of the cylinder barrel 1 on the screw shafts 6 and 6', respectively. 6′c′ is formed,
This is a slot that controls the melting range of the polymer.
Reference numerals 6d and 6'd designate discharge screw portions, which are the final stages in which flights 6d' and 6'd' are formed on the screw shafts 6 and 6' to discharge the molten polymer.

The four-stage twin-screw extruder shown in Fig.
In the third stage to the third stage, the screw shafts 6, 6' are connected to the feed sections 6a, 6'a and the rotor section 6.
b, 6'b and slot portions 6c, 6'c, and in the fourth and final stage, the screw shafts 6, 6' are connected to the discharge screw portions 6d, 6'c.
Consisting of 6'd.

In addition, in the three-stage twin-screw extruder shown in FIG. 3, the screw shaft 6 consists of a feed section 6a, a rotor section 6b, and a slot section 6c in the first and second stages, and in the third stage, which is the final stage, The screw shaft 6 consists of a discharge screw portion 6d.

By connecting a granulation die to the discharge port 3 as necessary, this twin-screw extruder can perform dehydration,
Used as a 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 fed to the feed section 6 of the first stage.
a, 6'a, the inside of the cylinder barrel 1 is forced to the front, and a large amount of water is squeezed out through the slit portion 5.
The water is drained outside the cylinder barrel 1. In the rotor parts 6b, 6'b, the slot parts 6c,
Under the influence of 6'c, the polymer becomes plasticized,
The water is further separated and sent under pressure to the second stage.
The polymer sent to the second stage is passed through the slit section 5.
Mainly, residual moisture is discharged, and volatile matter and water vapor are degassed from the vent hole 4, and the rotor portion 6b,
6'b, and the slot portions 6c, 6'c in the same manner as the first stage, and is pumped to the third stage.
In the third stage, the plasticization of the polymer progresses, and the volatile components of water vapor are degassed through the vent hole 4, and the rotor parts 6b, 6'b, slot part 6c,
Under the action of 6'c, it is pumped to the fourth stage,
The completely melted polymer is further degassed through the vent hole 4 and discharged from the discharge port 3 by the action of the discharge screw portions 6d, 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 takes 0.5Kwhr/
When a water-containing polymer that required a specific energy of Kg was processed to a similar dry state using the twin-screw extruder according to the present invention, the specific energy required for drying was 0.2 kwhr/Kg.
In the case of 0.7kwhr/Kg, the result was 0.3kwhr/Kg.

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 almost no polymer leaks out from the slit section. Nakatsuta.

The twin-screw extruder according to the present invention includes a first stage in which a feed section, a rotor section, and a slot section are formed in sequence, an intermediate stage connected to this, and a discharge screw section connected to the intermediate stage. The screw shaft has two screw shafts that mesh with each other and rotate in opposite directions, and a material supply port is formed at the base end and a discharge port is formed at the tip, respectively.
In a twin-screw extruder configured by inserting the cylinder barrel into a cylinder barrel having vent holes for degassing on the front side near each slot part, at least the lower part of the cylinder barrel where the feed part of the first stage is located. A slit section for dehydrating the hydrous polymer is provided in the slit section.

Therefore, even if powdered or crumb-like polymer containing a large amount of water (20 to 70% by weight) is directly supplied, it can be dehydrated and degassed without causing insufficient biting into the screw or insufficient extrusion amount. We were able to provide a twin-screw extruder that can supply a molten polymer, 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 extruder according to the present invention, Fig. 2 is a cross-sectional view taken along the - line in Fig. 1, and Fig. 3 is a cross-sectional view of a three-stage twin-screw extruder according to the present invention. FIG. 1: Cylinder barrel, 2: Material supply port, 3: Discharge port, 4: Vent hole, 5: Slit portion, 6,
6': Screw shaft, 6a, 6'a: Feed part,
6a', 6'a': Flight, 6b, 6'b: Rotor section, 6b', 6'b': Rotor, 6c, 6'c: Slot section, 6c', 6'c': Land, 6d, 6'd: Discharge screw part, 6d', 6'd': Flight.

Claims (1)

[Claims] 1 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 to form a discharge screw part, and Two screw shafts that mesh with each other and rotate in the opposite direction are formed with a material supply port at the base end and a discharge port at the tip, and vent holes for degassing are attached to the forward side near each slot section. In a twin-screw extruder configured by inserting the cylinder into a cylinder barrel,
A twin-screw extruder characterized in that a slit section for dehydrating a hydrous polymer is provided at least at the bottom of the cylinder barrel where the feed section of the first stage is located.