JPH10296728A - Method and apparatus for cleaning water soluble impurities in resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for cleaning water soluble impurities in resin to effectively clean water soluble impurities contained in resin by putting a screw and a barrel together. SOLUTION: The method and apparatus for cleaning water soluble impurities in resin is, in a cleaning method in which by an extruder having a pair of screws 2 rotating in the same direction in the barrel 1, resin is kneaded and melted to then be kneaded and dispersed by pouring water therein, and impurities contained in resin is discharged with water, thereby cleaning water soluble impurities in resin, such that by the use of a dispersion kneading area C, a residual area D, and a squeezing area E, at first water is poured in resin being kneaded and melted to subsequently be kneaded and dispersed, and by keeping a water dispersion state in resin, water in resin is followed by being squeezed out and discharged therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for cleaning water-soluble impurities in a resin, and more particularly to a novel improvement for efficiently cleaning water-soluble impurities contained in a resin by a combination of a screw and a barrel. About.

[0002]

2. Description of the Related Art As a conventional apparatus for cleaning water-soluble impurities in a resin using water, there is generally an apparatus having a structure shown in FIG. That is, FIG. 2 shows an apparatus for cleaning water-soluble impurities in a resin (a twin-screw extruder).
FIG. 2 is an axial sectional view and a resin pressure diagram partially showing a washing portion at one position. In this washing portion, a slit 3 for allowing water to escape in a barrel 1 is provided, and a screw 2 has a forward full flight element 4. And a forward full flight element 4, a flow resistant screw element 5, and a reverse full flight element 6 which are located downstream (to the right in the drawing) of the separation area A and are arranged from the upstream side. And a cleaning throttle area B composed of the barrel 1 having a water inlet 7 at the position of the forward full flight element 4. The separation area A of the next cleaning section is continuously provided downstream of the cleaning throttle area B. In the barrel 1, a pair of screws 2 rotating in the same direction overlap each other (only one screw is shown).
It is provided rotatably in a meshed state.

In the above-mentioned conventional configuration, in a state where the resin supplied from an upstream material supply port (not shown) is kneaded, melted and extruded by the screw 2, the resin is sequentially transported downstream in the separation area A. At the same time, in the water area separated from the resin, water flowing backward from the downstream of the cleaning throttle area B is discharged to the outside through the slit 3. In the separation area A, the resin is transported by a weak shearing force, so that the resin pressure is low,
The screw 2 is partially filled, and a gap for flowing water is formed. Further, in the cleaning throttle region B, water (or hot water) is injected from the water injection port 7 into the resin gradually filled by the forward full flight element 4, and water is dispersed and kneaded in the resin by the flow-resistant screw element 5. Is done. The dispersed water comes into contact with the water-soluble impurities, and the water-soluble impurities diffuse into the water to wash the water-soluble impurities. Therefore, the water containing the water-soluble impurities is squeezed out of the resin by the blocking action of the reverse full flight element 6. Then, the squeezed water flows back to the upstream separation area A as described above. In addition, a plurality of cleaning units are continuously provided as necessary, and the above-described resin cleaning is repeatedly performed to improve the cleaning effect.

[0004]

Since the conventional method and apparatus for cleaning water-soluble impurities in a resin have been constructed as described above, the following problems exist. That is, in the separation region A, the molten resin flowing from the upstream side or the resin that is insufficiently melted, or the molten resin once squeezed in the upstream cleaning section may pass without any cleaning effect, In the cleaning squeezing area B, water is injected in a state where the resin is low in the upstream part and the pressure is almost zero or the pressure is insufficient, and then, while the resin is pressurized, the water is kneaded into the resin. Since the dispersion is performed, the washing of the water-soluble impurities and the squeezing of the water are to be performed at once.

Accordingly, in the separation area A, there is no or almost no water in the resin, and the water-soluble impurities in the resin are not cleaned in this area. Also,
In the cleaning throttle area B, water is injected during the pressurization of the resin, and a part of the water is to be immediately squeezed out without being used for cleaning the water-soluble impurities. Furthermore, when water is dispersed in the molten resin and washed, the concentration of the water-soluble impurities in the resin and the concentration in the water are in equilibrium, and a predetermined time is required for the water-soluble impurities to diffuse from the resin into the water. Although necessary, the cleaning aperture area B is short and the residence time (passage) of the resin is short, so that the cleaning is not sufficiently performed. In other words, each area of the cleaning section does not act sufficiently for cleaning, which is inefficient.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in particular, a water-soluble resin contained in a resin which is efficiently washed with a combination of a screw and a barrel to remove water-soluble impurities contained in the resin. An object of the present invention is to provide a method and an apparatus for cleaning impurities.

[0007]

According to the present invention, there is provided a method for cleaning water-soluble impurities in a resin, wherein the resin is kneaded and melted by an extruder having a pair of co-rotating screws in a barrel, and water is injected. Kneading and dispersing, in the method of cleaning the water-soluble impurities in the resin to discharge the water-soluble impurities contained in the resin together with the water, the resin kneaded and melted in the dispersion kneading region, first water is injected and dispersed and kneaded in the resin, Next, a method in which the dispersion state of the water in the resin is maintained in the stagnation region, and then the water in the resin is squeezed out in the squeezing region and discharged.

According to the present invention, there is provided an apparatus for cleaning water-soluble impurities in a resin, wherein a pair of co-rotating screws are rotatably provided in a barrel so as to overlap with each other and mesh with each other. In the water-soluble impurity cleaning device, the screw is formed of a kneading element and a blister ring on the downstream side of the kneading element, and a water injection port is provided at the kneading element portion of the barrel. The dispersing and kneading area provided, the screw is constituted by a forward full flight element, and a retaining area in which the barrel is provided with a slit for discharging water, and the screw comprises the forward full flight element and the blister on the downstream side thereof. This is a configuration in which a cleaning unit for arranging an aperture region formed by a ring is provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method and an apparatus for cleaning water-soluble impurities in a resin according to the present invention will be described below in detail with reference to the drawings. Note that the same or equivalent parts as those in the conventional example will be described using the same reference numerals. FIG. 1 is an axial cross-sectional view and a resin pressure diagram partially showing a cleaning section at one place of an apparatus (a twin-screw extruder) for cleaning water-soluble impurities in a resin according to the present invention.

In FIG. 1, reference numeral 1 denotes a barrel of a twin-screw extruder, in which a pair of co-rotating screws 2 (only one is shown) are meshed with each other so as to overlap each other. It is provided rotatably in the state. The twin-screw extruder is provided with a washing section comprising a dispersion kneading area C, a stagnation area D, and a squeezing area E in sequence downstream (to the right in the figure) of the kneading and melting section.

In the dispersion kneading area C, the screw 2 is provided with a kneading element 8 such as a kneading disk.
And a blister ring 9 downstream thereof, and a water inlet 7 for water is provided at a position of the kneading element 8 of the barrel 1. The stay area D
The screw 2 is composed of a forward full flight element 4 and the barrel 1 is provided with a slit 3 for discharging water. In the throttle region E, the screw 2 is constituted by the forward full flight element 4 and a blister ring 9 downstream thereof.

In the apparatus for cleaning water-soluble impurities in a resin thus constituted, the resin containing water-soluble impurities supplied from an upstream material supply port (not shown) is kneaded and extruded by the screw 2. In this state, water-soluble impurities contained in the kneaded and melted resin are washed and separated and discharged as follows in a washing section including the following regions C, D, and E. That is, in the dispersion kneading region C, the resin containing water-soluble impurities is kneaded while water (or hot water) is injected from the water inlet 7 at a pressure higher than the vapor pressure. As a result, the injected water is finely dispersed in a high-pressure resin by the kneading action of the kneading element 8 and the blocking action of the blister ring 9 in a state of water (liquid),
Sufficiently contacts with water-soluble impurities contained in resin. The water-soluble impurities are sufficiently diffused and dissolved into the water dispersed in the resin, that is, the resin containing the water-soluble impurities is washed.

In the next staying region D, the resin in which water is dispersed and kneaded is transported in a partially filled state by the transport action of the forward full flight element 4, so that the resin receives a weak shearing force and has a low pressure. As a result, a part of the dispersed water is released containing water-soluble impurities and discharged from the slit 3. Therefore, the contact time between water-soluble impurities and water (residence time of water in the resin) is extended, and the cleaning effect is improved by increasing the concentration of water-soluble impurities to the maximum equilibrium state.

Further, in the constricted area E, the resin fills the full flight of the screw 2 by the transport action of the forward full flight element 4 and the blocking action of the blister ring 9. As a result, the internal pressure of the resin increases, and the water dispersed in the resin is squeezed out. The squeezed water is discharged from the discharge slit 3 to the outside in the retention region D. In addition, it is more effective to provide a plurality of the above-described cleaning units continuously as necessary and repeatedly perform the above-described resin cleaning.

[0015]

EXAMPLE A comparative test of the cleaning action was performed on the conventional cleaning apparatus shown in FIG. 2 and the cleaning apparatus according to the present invention shown in FIG. Extruder: TEX44 meshing co-rotating twin screw extruder
(Manufactured by Nippon Steel Works) Resin: Emulsion polymer containing 3,000 ppm of sodium Resin flow rate: 50 kg / h Hot water added: 125 kg / h As a result of the test, the sodium content in the resin after washing at the outlet of the extruder is the conventional value. Cleaning apparatus: about 800 ppm Cleaning apparatus according to the present invention: 500 ppm or less.

[0016]

As described above, the method and apparatus for cleaning water-soluble impurities in a resin according to the present invention have the following effects. That is, the water is dispersed and kneaded in the resin in the dispersion kneading region C, the contact time between the resin for diffusing the water-soluble impurities into water and the water in the retention region D is ensured, and the water-soluble impurities are contained in the narrowing region E. Since the water is easily squeezed out, each region of the cleaning unit exerts an efficient cleaning action without waste, and water-soluble impurities in the resin can be efficiently cleaned.

[Brief description of the drawings]

FIG. 1 is an axial cross-section partially showing a cleaning section of an apparatus (a twin-screw extruder) for cleaning water-soluble impurities in a resin according to the present invention and characteristics of a resin pressure corresponding to the cross-section. FIG.

FIG. 2 shows an axial section partially showing one washing section of a conventional apparatus (biaxial screw type extruder) for washing water-soluble impurities in a resin, and a resin pressure characteristic corresponding to this section. FIG.

[Explanation of symbols]

 Reference Signs List 1 barrel 2 screw 3 discharge slit 4 forward full flight element 7 water inlet 8 kneading element 9 blister ring C dispersion kneading area D staying area E throttle area

Claims (2)

[Claims] An extruder having a pair of co-rotating screws (2) in a barrel (1) kneads and melts a resin.
Injecting water, kneading and dispersing, in a method for cleaning water-soluble impurities in a resin in which water-soluble impurities contained in the resin are discharged together with water, water is first poured into the resin kneaded and melted in the dispersion kneading region (C). Dispersing and kneading the resin in the resin, then maintaining the dispersion state of the water in the resin in the stagnation region (D), and then squeezing out the water in the resin in the squeezing region (E) and discharging the resin. Cleaning method for water-soluble impurities. 2. An apparatus for cleaning water-soluble impurities in a resin, comprising an extruder rotatably provided in a barrel (1) with a pair of co-rotating screws (2) overlapping and meshing with each other. In the downstream of the kneading and melting section, the screw (2) is sequentially formed of a kneading element (8) and a blister ring (9) on the downstream side thereof, and the kneading element (8) of the barrel (1) is formed. ) Is provided with a water mixing port (7) provided with a water inlet (7), the screw (2) is composed of a forward full flight element (4), and the barrel (1) is used for discharging water. A staying area (D) provided with a slit (3), and a throttle area (E) in which the screw (2) is formed by the forward full flight element (4) and the blister ring (9) downstream thereof. Water soluble in resin characterized by being provided with a washing section to be arranged Cleaning equipment for impurities.