JPS59210967A - Production of abs resin - Google Patents

Abstract

PURPOSE:To produce an ABS resin which has good physical properties and less variability of characteristics, by feeding to a dehydrating compounder a hydrated ABS resin while keeping the net weight of the polymer constant and an AS polymer before the completion of ventilation. CONSTITUTION:An emulsion-polymerized ABS polymer having a water content of 10-100% from a hopper 36 through a weigh-feeder 31 and an AS polymer from a continuous metering feeder 44 are fed through a raw material feed opening 37 to a twin-screw dehydrating compounder 36 to remove most of water in the raw materials in a dehydrating part 39, and gases contained therein are discharged through a vent hole 38. Additives such as stabilizer, etc. from a constant feeder 40 are then added and the resulting mixture is granulated. In the above method, the water content of the ABS resin fed from the feeder 31 is measured by a sensor 41, the measured value is compared with a value preset in a setting device 42 in a comparator 43, a motor 32 is controlled by the resulting differential signal (numeral 33 being screw) and the signal is converted into the quantity of water removed to thereby feed a given quantity of the ABS resin to the compounder 36.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves dehydrating and kneading ABS resin material having a moisture content of 10 to 100% using a twin-screw dehydration compounder.
The present invention relates to a method for producing ABS resin by mixing.

Polymer materials such as ABS resin obtained by emulsion polymerization contain a large amount of water and unreacted monomers even after removing water by centrifugal dehydration, etc., and granulation of this type of material in a single-screw extruder is difficult. is generally not possible except in limited ways.

The conventional method, which is one of the limited methods mentioned above, will be explained with reference to Figure 1.The moisture content is reduced to about 0.5 to 0.1% after passing through a flash dryer, fluidized dryer, etc. (not shown). The materials are fed into the mixer 2 via the weighing hopper 1, and at the same time, additives such as stabilizers are fed into the weighing hopper 4 from the piping 3, mixed at high speed, and fed to the pent extruder 6 via the hopper 5. This is a method in which the pellets are pelletized using a pelletizer 7.

According to this method, granulation is possible, but the moisture content is 10 to 1.
The equipment for reducing 0.00% material to 0.5-0.1% has drawbacks such as being very expensive and having a single screw extruder which makes mixing and kneading poor.

Therefore, the inventors of the present invention filed an application earlier and published it in JP-A No. 5
4-270 and JP-A-54-5271, the material is mechanically compressed in advance from a material supply source to a vented twin-screw extruder that can mix and knead materials well before reaching the vent part. We proposed a twin-screw extruder that is equipped with a dewatering section, and after removing most of the water in the dehydrating section, the remaining water and volatile matter are removed at a vent section.

According to this method, materials with a moisture content of 10 to 100%, which were conventionally transferred from the polymerization process as in reloading, can be dehydrated without much cost, and granulation is also possible. A problem occurred. This is because when the water is removed in the dehydration section of the extruder, the necessary antioxidant additives put into the material are removed together with a large amount of water, or even if they remain, the amount is small. The problem is that pellets that are granulated without being controlled are of inferior commercial value.

Therefore, the inventors have come to the conclusion that the twin-screw compounder can produce pellets uniformly containing additives by metering and supplying the additives after removing the contained water.

In addition, when AS materials obtained by suspension polymerization are added to ABS materials obtained by emulsion polymerization as additives at various mixing ratios, such as when producing various grades of ABS polymers, Although the AS material used as an additive has a relatively low volatile component content, the AS polymer contains styrene monomer, and it is necessary to extract this styrene monomer.

Therefore, when using this type of material as an additive, it is completely pointless to add it as an additive after the venting function is completed, and the excess styrene monomer cannot be removed, at least before the venting function is completed. must be added to.

That is, the present invention provides an apparatus for detecting water content at the inlet, outlet, or inside of a method for producing ABS resin by mixing an AS polymer with an ABS polymer obtained by emulsion polymerization containing 10 to 100% water. The ABS polymer is supplied from the metering type continuous supply rock equipped with the AB, and the AS polymer is supplied from the quantitative supply device at least before the completion of the venting function to the two-shaft dewatering compounder equipped with the vent.
The moisture content of the S polymer is detected, the detected value is compared with a preset moisture content value, and the supply amount of ABS polymer is increased or decreased so that the net polymer supply amount is constant due to changes in the moisture content. This is a characteristic method for producing ABS resin.

Next, the present invention will be explained using FIG. 2 as an example of an apparatus suitable for carrying out the present invention.

In FIG. 2, reference numeral 31 denotes a gravimetric feeder (gravimetric heavy type feeder), and a screw 33 is rotationally driven by a motor 32. When water-containing ABS polymer is fed into a hopper 34 from a decanter (not shown), the screw 33 is rotated by a motor 32.
3 is transferred to the feeder outlet 35 by the rotation of the extruder 3.
The raw material is transported to the raw material supply port 37 of No. 6. The extruder 36 is a twin-screw extruder to ensure sufficient cross-mixing of the materials. In addition, the vent hole 38 and the raw material supply port 3
7, there is a dehydration section 3 that removes water contained in the material.
9 is provided to remove most of the moisture from the material supplied from the raw material supply port 37. Reference numeral 40 denotes a metering supply device for supplying additives, which is designed to compensate for the above-mentioned drawbacks and to supply additives and the like while metering after removing the water contained therein.

In addition, the AS polymer is supplied either by metering type continuous supply device 44 to the feed port 37 or from the vent hole 3.
8, or in the case where there are two vent holes, it needs to be located at least before the extrusion port side vent hole, that is, upstream with respect to the flow of the material.

When such a supply device 44 is provided, a method of gravity dropping so that there is no resin pressure at the additive supply position,
Alternatively, if the resin pressure in the extruder is high (for example, in the case immediately before the vent hole), supply is performed using a push screw.

The gravimetric feeder 31 continuously feeds the material to the extruder 36 while metering the material to keep the ratio of each component constant. However, here the supplied A
Regarding the water content of the BS polymer, conditions such as slurry temperature and decanter are not completely controlled, and fluctuations are inevitable. That is, when the feed rate of the water-containing ABS polymer is controlled by the feeder 31, the net amount of the polymer changes as the water content changes, and as a result, the content of the AS polymer also changes, even though the overall weight is the same. Due to fluctuations in water content, the composition ratio of ABS polymer and AS polymer in the ABS resin changes, making it impossible to produce a uniform product.

Therefore, for example, a sensor 41 for measuring moisture content by infrared absorption is installed at or near the feeder 31,
The measurement value measured by the sensor 41 and the setting device 4
A comparator 43 compares the moisture contents set at 2 and applies a signal based on the deviation to the drive motor 32 to
The amount of water-containing ABS polymer supplied is increased or decreased so as to eliminate any change in the net amount of material supplied to 6 and remain constant.

As explained above, in the production method of the present invention, the drawbacks listed at the beginning are eliminated, and the kneading and mixing of ABS polymer and AS polymer with a water content of 10 to 100% is good.

The present invention will be explained below with reference to Examples.

Example ABS polymer latex obtained by aqueous emulsion polymerization of 30 parts by weight of polybutadiene (as polymer content), 50 parts by weight of styrene, and 70 parts by weight of acrylonitrile was coagulated with a salting-out agent, and then dehydrated with a centrifugal dehydrator. , water content (parts by weight of water relative to 100 parts by weight of polymer) of 40% by weight A
A wet cake of BS polymer was obtained.

Further, an AS polymer obtained by suspension polymerization of 75 parts by weight of styrene and 25 parts by weight of acrylonitrile was dehydrated and then dried to obtain beads. The amount of residual styrene in the beads of this AS polymer is 20% by weight, and the amount of residual acrylonitrile is 0.5% by weight.
Met.

The above ABS polymer wet cake and AS polymer beads were dehydrated and kneaded using the apparatus shown in FIG. 2 to obtain pellets.

That is, the moisture content is set to 40% by weight in the setting device 42,
ABS polymer wet cake was continuously introduced at a rate of 70 kg per hour. Gravimetric feeder 3
1, and the moisture content is measured by the sensor 41. This measured value and the moisture content preset by the setting device 42 are compared by the comparator 43, and a signal based on the deviation is applied to the drive motor 32. The amount of wet cake supplied was adjusted so as to keep the net amount of ABS polymer supplied to the supply port 37 of the extruder 36 constant. In this manner, the ABS polymer wet cake was supplied to the supply port 37 while adjusting its weight. On the other hand, AS polymer beads were continuously supplied to the supply port 37 at a rate of 50 Kg/Hr while being measured by a metering type continuous supply device 44.

The screw rotation speed of the twin-screw extruder 36 is 300 rpm, and the temperature of the barrel is 100°C to 250°C from the inlet to the outlet.
It was set to rise in stages.

The ABS polymer wet cake and AS polymer beads introduced into the supply port 37 were kneaded and dehydrated, and the kneading was continued while the dehydrated water was extracted in the dehydration section 39. Further, the degassed air was removed from the vent hole 38. 0.5Kg of stabilizer from the metering device installed at the rear of the extruder
/Hr was added.

The ABS polymer and AS polymer kneaded in this way were finally pelletized and taken out.

During operation, ABS resin pellets were sampled every hour for 5 hours and their properties and physical properties were measured. Table 1 shows the results.

From Table 1, it can be seen that the ABS resin produced by the method of the present invention has good properties and physical properties, and has small rosy.

[Brief explanation of drawings]

FIG. 1 shows an example of a conventional apparatus, and FIG. 2 shows an example of an apparatus used in the method of the present invention. 31... Weigh scale heavy feeder, 32... Drive motor, 33... Screw, 41... Moisture measurement sensor, 42... Setting device, 43... Comparator, 44... Measuring type continuous feeding device.

Claims (1)

[Claims] In the method of manufacturing ABS resin by mixing AS polymer with ABS polymer obtained by emulsion polymerization containing 10 to 100% water, a weighing type with a device for detecting water content installed at the inlet, outlet, or inside. ABS from continuous feeding machine
The polymer, and at least before the completion of the venting function, the AS polymer is supplied one by one from the metering device to the two-shaft dehydration compounder with a vent, and the moisture content of the ABS polymer is detected, and the detected value and the preset moisture content are Compare with the value,
A method for producing ABS resin characterized by increasing or decreasing the supply amount of ABS polymer so that the net polymer supply amount is constant due to changes in moisture content.