JPS60229937A - Method for recovering polymer - Google Patents

Abstract

PURPOSE:To recover a graft copolymer having good quality with improved recovery operability and productivity, by mixing a mixture solution of a graft polymer latex with a thermoplastic resin solution and an aqueous solution of a coagulating agent under a specific shear rate. CONSTITUTION:(A) A graft polymer latex with 30-80wt% rubber content obtained by grafting a vinyl based monomer in the presence of a rubber-like polymer latex is mixed with (B) a thermoplastic resin solution obtained by solution polymerization or bulk polymerization of a vinyl based monomer in an organic solvent (polymerization solution is directly used) and (C) an aqueous solution of a coagulating agent by feeding the components (B) and (C) quantitatively to a mixer respectively with pumps, thoroughly mixing them, feeding the resultant mixture to the next mixer, and feeding the previously adjusted component (A) quantitatively thereto with a pump. After mixing the component (A) therewith at >=100sec<-1>, preferably >=200sec<-1> shear rate in the mixer, the resultant mixture is then fed to a screw type dehydrator and drained, and the residual volatile matter is then evaporated in an extruder.

Description

[Detailed description of the invention] The present invention relates to a method for recovering a graft copolymer.

More specifically, the present invention relates to a method for recovering a graft copolymer from a graft copolymer latex, which has excellent recovery workability, productivity, and quality of the recovered graft copolymer.

The method for recovering the polymer from the polymer latex is to mix the polymer latex with an organic solvent and extract the polymer with the organic solvent, and to add a so-called coagulant, which is a drug that deactivates the emulsifier contained in the polymer latex. Conventionally, methods have been used to separate and recover the liberated polymer. However, the former method has the disadvantage of requiring a great deal of effort to separate the organic solvent and polymer, and also requires a large amount of energizing liquid (the latter method is used to coalesce the fine polymers that have coagulated and become free). It requires extremely diverse steps such as granulation, filtration or centrifugal dehydration, and then drying the powder with a fairly high water content in a flash dryer to recover the polymer.
There are many undesirable points such as high drying cost, large polymer loss during the process, difficulty in avoiding contamination with impurities, and high labor costs.

Furthermore, in ABS resin, the rubber content is 30% by weight.
The method of producing the above-mentioned graft copolymer with a high rubber content and blending it with 6 resins (acrylonitrile-styrene copolymer) to obtain an ABS resin with the desired rubber content is effective in terms of productivity and versatility. Recently, it has been widely used because ABS of various types can be obtained. However, when recovering a graft copolymer from a graft copolymer latex with a high rubber content of 30 parts by weight or more, the latter method is generally used to reduce bulk specific gravity in the coagulation process. Small powder is generated, so the dehydration process,
There are problems in that workability is significantly reduced during the drying process, and furthermore, it is easy to catch fire during drying, and quality, such as color tone, gloss, and mechanical strength, is significantly reduced.

In order to improve these shortcomings, various studies have been carried out in the past. Publication No. 34-10488), (b)
A method of shaping a paste consisting of a polymer latex and a coagulant, and heating this shaping paste in an aqueous solution to harden and synergate the polymer particles (Japanese Patent Publication No. 42-22295), (c) (b) A method for producing paste using a screw type (Japanese Patent Publication No. 42-22684), (
d) Using a screw type dehydration dryer, mechanical squeezing is performed at the rear end of the screw to remove most of the water from the latex, and the remaining water is evaporated and dried using the exhaust port located at the tip of the screw. A method of continuously recovering a molten polymer (Japanese Patent Publication No. 17277/1983) has been proposed. However, although most of the water is removed using a press in the method (1), an extra step of pulverizing the condensate is added, resulting in the generation of fine powder and a decrease in quality.

Moreover, there is still a step of washing and drying the pulverized polymer. Although methods (b) and (c) simplify the dehydration process to some extent, they also have the problem that the coagulated polymer is dispersed in the aqueous solution without being granulated, resulting in a large loss of polymer. However, there is still room for improvement in the dehydration and drying process of granules. In addition, method (2) is superior in that it can simplify the process of recovering the polymer from latex using a screw-type dehydrator/dryer, but the mechanical squeezing of the coagulated material is not stable, resulting in fine polymer particles. The water passes through the screen bar for dehydration and is lost. Another disadvantage is that a phenomenon in which the polymer is entrained in the evaporated material to the exhaust port (vent-up) occurs, making the operation of the screw dewatering/drying machine unstable and making it difficult to increase productivity.

On the other hand, methods for recovering polymers from thermoplastic resin solutions obtained by solution polymerization or bulk polymerization include methods for recovering polymers by evaporating organic solvents and unreacted monomers by steam stripping, and methods for recovering polymers by evaporating organic solvents and unreacted monomers by steam stripping. There are a method in which a poor solvent is added to precipitate and recover the polymer, and a method in which the organic solvent and unreacted monomer are directly evaporated and removed using a vent extruder to recover the polymer.

The steam stripping method requires a large amount of steam;
Furthermore, since the precipitated polymer is in the form of a large lump, many steps are required to mold it into a desired molded product. Further, the precipitation method in a poor solvent has the disadvantage that a large amount of a poor solvent is used, which causes high costs, and the precipitated polymer becomes fine particles, resulting in large losses during the process. Therefore, the best method is to recover the polymer by direct devolatilization using a vented extruder as described at the end, but the polymer is subjected to high shear action under high temperature conditions in the extruder, and this In order to blend it with the emulsion graft polymer described above, melt-mixing it again in an extruder involves a lot of energy loss, and it also exposes the polymer to harsh processing conditions many times. This results in undesirable results in terms of quality, such as impairing the color tone of the product.

Even with the method proposed above, sufficient results can be obtained in terms of productivity due to polymer loss, workability of recovery, and quality when recovering the graft copolymer from graft copolymer latex. However, it was a challenge for those skilled in the art to improve it. In particular, when a graft copolymer latex with a high rubber content is used, the above-mentioned drawbacks become more noticeable.

Therefore, the present inventors conducted intensive studies to improve these shortcomings of the conventional technology and to obtain a simplified method for recovering graft copolymers, and as a result, they recovered graft copolymers from graft copolymer latex. By mixing a mixed solution of graft polymer latex, thermoplastic resin solution, and coagulant aqueous solution at a specific shear rate in the process of Completely unexpected and excellent effects such as superior quality, color tone, and mechanical strength of the copolymer were obtained, and by carrying out this method, conventionally the graft copolymer and the vinyl polymer were recovered separately. The desired quality was obtained by blending the recovered materials, but the complicated process 1-
The present invention was achieved by discovering a method by which a rubber-modified thermoplastic phase consisting of a graft copolymer and a vinyl polymer can be easily recovered without carrying out the following steps.

That is, the present invention provides a method for recovering a kraft copolymer from a graft copolymer latex, in which ta) a rubber content of 30 to 80% obtained by graft polymerizing a vinyl monomer in the presence of a rubbery polymer latex; % by weight of graft polymer latex, a thermoplastic resin solution obtained by solution polymerization or bulk polymerization of FBL vinyl monomer in an organic solvent, and (C1 coagulant aqueous solution) at a shear rate of 1001
Rubber content: 5~
A method for recovering 60% by weight of rubber-modified thermoplastic resin is provided.

The present invention will be explained in detail below.

The above (a) graft polymer latex includes (a)
Polybutadiene, butadiene-styrene copolymer (SB
, R), butadiene-acrylonitrile copolymer (N
BI? ), diene-based rubbery polymers such as inbrene rubber and chloroprene rubber, acrylate ester-2-chloroethyl vinyl ether copolymers, ethylene-propylene copolymers, and ethylene-propylene-diene terpolymers. Diene-based rubbery polymer (
b) Aromatic vinyl monomers such as styrene, α-methyl, and rustyrene; vinyl cyanide monomers such as acrylonitrile and methyl methacrylate; and alkyl methacrylates such as methyl methacrylate and ethyl methacrylate. Examples include latex with a rubber content of 30 to 80% by weight obtained by graft polymerization of monomers.

The emulsifier, initiator, and other chemicals used in graft polymerization are not limited in any way in the present invention, and any chemicals used in normal emulsion polymerization may be used.

For example, as initiators for graft polymerization, organic hydroperoxides such as cumene hydroperoxide and cyisopropylhenine hydroperoxide, and reducing agents such as sugar-containing pyrophosphoric acid formulations, sulfoxylate formulations, etc. In addition, persulfates such as potassium persulfate and ammonium persulfate, abbisisobutyronitrile, hensyl peroxide, and the like can be optionally used.

Further, as the molecular weight regulator, mercaptans such as normal octyl mercaptan, normal dodecyl mercaptan, tertiary dodecyl mercaptan, and mercaptoethanol, halogenated carbons such as chloroborum and carbon tetrachloride, and hydrogen hydride can be used.

Examples of emulsifiers include rosinate salts such as potassium rosinate and sodium rosinate, alkali metal salts of fatty acids such as potassium oleate, sodium oleate, potassium laurate, sodium laurate, potassium stearate, and sodium stearate, and lauryl sulfate. Sulfate ester salts of aliphatic alcohols such as sodium, alkylaryl sulfonic acids such as sodium dodecylbenzenesulfonate, and the like can all be used.

There are no particular restrictions on the solid content concentration of latex, but
Preferably 20 to 50% by weight, more preferably 25 to 4% by weight
It is 0% by weight.

Also blend with this +b+v3. As the plastic resin, at least one of the vinyl monomers shown in (b) above is used.
Specific examples include homopolymers of these species or copolymers thereof, such as styrene-acrylonitrile copolymers, styrene-α-methylstyrene-acrylonitrile copolymers, and styrene-methyl methacrylate-acrylonitrile copolymers. These monomers are polymerized by solution polymerization or bulk polymerization, and the polymerization solution can be used as it is.

The organic solvent used in producing the thermoplastic resin solution used in the present invention is not particularly limited as long as it can melt or swell the thermoplastic resin.

Typical examples include aromatic hydrocarbon solvents such as benzene, toluene, and xylene, ketone solvents such as acetone and methyl ethyl ketone, and halogenated hydrocarbon solvents such as carbon tetrachloride and chloroform.

In addition, in the polymerization, ordinary organic peroxides or azo compounds can be used as a polymerization initiator, but it is not always necessary to use a polymerization initiator, and thermal polymerization can also be carried out without adding an initiator. can.

The solid content concentration of the thermoplastic resin solution is not particularly limited, but is preferably 30 to 85% by weight, more preferably 50 to 70% by weight.

The coagulant for coagulating the polymer latex is not particularly limited, and commonly used electrolyte inorganic salts such as sodium chloride and magnesium sulfate, and acidic substances such as inorganic acids and organic acids can be used.

A typical process diagram for continuously recovering a rubber-modified thermoplastic resin by mixing a graft polymer latex, a vinyl thermoplastic resin solution, and an aqueous coagulant solution according to the method of the present invention is shown in FIG. The present invention will be explained as follows with reference to FIG.

The thermoplastic resin solution and coagulant solution are quantitatively fed from the vinyl thermoplastic resin solution storage tank 1 and the coagulant storage tank 2 to the mixer 7 using pumps 4 and 5, respectively, and mixed thoroughly. The mixture is then supplied to the next mixer 8. On the other hand, a graft polymer latex having a rubber content of 30 to 80% by weight, prepared in advance from the latex storage tank 3, is quantitatively supplied to the mixer 8 using the pump 6.

The mixer 8 must have a high shear action with a shear rate of 1001/sec or more, preferably 2001/sec or more, more preferably 5001/sec or more. This high shear action has the effect of instantaneously coagulating the polymer in the latex, uniformly extracting and melting it into the thermoplastic resin solution, and liberating water in the latex.

If the shear rate of the mixer 8 is less than 1001/sec, the polymer in the latex cannot be uniformly extracted/dissolved into the thermoplastic resin solution, and some hard graft polymer lumps and Fine particles may be mixed in, clogging the mixer or subsequent transportation piping, or when free water is mechanically squeezed in the next process, fine particles may be lost along with the water, resulting in loss. This is not desirable. It is also undesirable because it causes a decrease in mechanical strength and a change in color tone.

1 Furthermore, if the rubber content of the graft polymer latex used exceeds 80% by weight, the grafting rate will be low and the mechanical strength, heat discoloration resistance, etc. will be significantly reduced, which is undesirable. If the rubber content is less than 30% by weight, MYi cannot be expected to achieve the above-mentioned productivity, variety of products, etc.

Furthermore, if the rubber content of the rubber-modified thermoplastic resin is less than 5% by bundle amount, the impact resistance of the product will be low and it will be impractical, and mechanical squeezing dehydration will be difficult due to the low viscosity of the rubber-modified thermoplastic resin. Undesirable. Further, if the rubber content of the rubber-modified thermoplastic resin exceeds 60% by weight, the rubber-modified thermoplastic resin becomes extremely viscous, making transportation by piping difficult, which is not preferable.

Next, the mixed solution is sent from the mixer 8 to a dehydrator 9 for dehydration. Due to the effect of the high shear action of the mixer 8, at the outlet of the mixer 8, most of the water in the latex is in a free state, and only a small part is obtained in a microdispersed state in the polymer solution. Most of the water can be separated with slight compression, the energy required for dewatering is small, and there is no polymer loss from the open I part for drainage of the dehydrator.

As the type of dehydrator, a general screw type dehydrator can be used, and either a single screw or a double screw can be used.

The one shown in Figure 1 is an example of a tilted squeezing dehydration screw, which uses a screw with a high compression ratio.The screw is tilted so that the squeezed water can be easily drained, and a groove is cut in a part of the body. It has a J structure. The squeezed water is discharged out of the system as waste water 10 along this slope through a slit at the rear end of the flow screw.

The mechanically squeezed and dehydrated polymer molten skin is supplied from the tip of the dehydrator 9 to a vent extruder 111, which is then moved to a vacuum pump 13 by mechanical energy from the rotation of the screws and, if necessary, heating from the jacket. The R'/G medium, unreacted monomers, and residual water are evaporated and separated from the vent under reduced pressure, and the polymer is extruded through the extruder product 1 and cut into pellets of appropriate size to produce product 15. The rubber-modified thermoplastic resin can be continuously recovered as a rubber-modified thermoplastic resin. Also, the organic solvent separated from the vent,
Unreacted monomers are condensed in a condenser 12 and can be recovered as a condensate 14 and reused.

The type of vent extruder is not particularly limited, and any conventional extruder having one or more vents can be used. The number of vent stages is determined depending on the amount of residual solvent and unreacted upper particulate matter to be removed. If desired, the dehydrator 9 and the vent extruder 11 can be combined into one device, and a mechanical squeezing dehydration function can be provided between the polymer inlet and the first vent, and then installed at the tip of the screw. The rubber-modified thermoplastic resin can be recovered in a manner similar to that described above by evaporating the interrogating solvent, unreacted monomers, and residual polar water (a small amount of water) from one or more vents.

As described above, according to the present invention, it is possible to recover a rubber-modified thermoplastic resin from latex and a thermoplastic resin solution continuously and in a process that is much simpler than the conventional method. The method of removing most of the water in latex by mechanical squeezing according to the present invention can dehydrate the latex at an extremely superior dehydration rate compared to conventional methods, such as methods using centrifugation.
It is advantageous in terms of energy saving. In addition, in the conventional method of removing water by evaporation, emulsifiers and coagulants remain in the rubber-modified thermoplastic resin, whereas in the method of mechanical squeezing as in the present invention, water is removed at the same time as the water being squeezed out. This is preferable because emulsifiers and coagulants can be removed, resulting in a thermoplastic resin with extremely good color tone and improved thermal stability and impact resistance.

Furthermore, compared to the case where latex is coagulated alone and dehydrated using a screw-type dehydrator, in the present invention, the coagulated polymer is extracted and dissolved in the thermoplastic resin solution, so it does not exist as fine particles. Therefore, fine particles are not lost through openings for drainage such as slits.

A part of it is micro-dispersed, and this promotes solvent removal, making it possible to obtain a rubber-modified thermoplastic resin with low residual volatile content and excellent quality.Also, if necessary, it can be added during the process. It is also possible to add agents.

There are no particular restrictions on where to add it, but in the case of water-soluble or powder additives; if they are not added after the dehydration step, they will be lost during ff water separation. For example, in the case of a liquid or solution additive that is preferably added midway through 11 in FIG. 1 or 21 in FIG. 3; mixing is easiest before the mixer 8.

Vent extruder 21 with dehydrator 9 or dehydration function
The inlet of the slit is undesirable because the additive may leak from the slit.

As for the types of additives, any desired ones can be added without particular limitation, such as anti-aging agents, fillers, and detergent pigments.

, especially the anti-aging agent added to latex in organic solvent 1
It is preferable to dissolve the compound in the latex and mix it in front of the mixer 8, since mixing and dispersion is better than adding it directly into the latex.

The present invention will be explained in more detail below using Examples. Note that parts in the examples indicate parts by weight.

Example 1 (A) A graft polymer latex having a rubber content of 60 parts was produced using the following polymerization recipe.

Polybutadiene latte/loss (solid content) 60 parts Styrene 14 Acrylonitrile 6 Tertiary lead decyl mercapkun 0.07 Water (including water in latex) 120 The above mixture was charged into a reactor equipped with a heating jacket and a stirrer, and nitrogen After replacing the internal air with
2 parts of sodium birophosphate dissolved in 1 part of water.
0.2 parts of dextrose, 0.003 parts of ferrous sulfate, and 0.41 parts of menhide "donkey oxide" were added and reacted.

One hour after starting the reaction, the following mixture was continuously added over 2 hours to obtain a graft polymer (ABS resin) latex with a polymerization rate of 98%.

Styrene 14 parts Acrylonitrile 6 Tertiary decyl mercabutane 0.070 Potassium sonate 1.0 Potassium hydroxide 0.03 Cumene hydroveroxite 0.1 Water 40 After the reaction, add 2,6 to this latex as an anti-aging agent.
0.5 part of -di-tert-butylvalacresol was added.

(B) On the other hand, a thermoplastic resin (As resin) was polymerized using the following polymerization recipe.

Styrene 75 parts Acrylonitrile 25 Toluene 3° Tertiary dodecyl mercaptan 0.1 The above mixture was charged into a reactor and heated at a temperature of 1.10 to 150'C.
Polymerization was carried out for a period of time to obtain an AS resin solution.

After the reaction was completed, the solid content in the polymer solution was measured and found to be 62
%Met.

Experiments were conducted on the obtained polymer according to the steps shown in FIG. That is, the daytime resin solution polymerized in (B) is stored in storage tank 1.
Add 10% magnesium sulfate water/8 liquid to storage tank 2.
Next, the ABS resin latex polymerized in (A) is stored in storage tank 3, and storage tank 1 is heated with a heating jacket to bring the internal temperature to 1.
It was kept at 20°C. First, use pump 4 and pump 5 to perform AS
resin solution at a flow rate of 50 kg/Ilr and 10%
An aqueous magnesium sulfate solution was fed at a flow rate of 3 kg/Hr, mixed in a mixer 7, and then supplied to a mixer 8. As the mixer 7, a 0-ketatic mixer having a diameter of 1'AP and several one or more elements was used.

On the other hand, ABS resin latex is pumped from the storage tank 3 into the liquid inlet 18 of the mixer 8 at a flow rate of 40 kg/Hr using the pump 6.
The mixture was supplied to the mixer 8 from The mixer 8 has a structure shown in FIG. 2, and stirs and mixes by the high shear action generated in the minute gap between the rotor R17 rotated at high speed by the drive motor 2o and the fixed ring 16. 17 with an outer diameter of 41,55vnO and a shear rate of 2500 ~
It was operated at 40001/sec. Next, the mixed/8 liquid at the liquid outlet 19 of the mixing R8 was sent to a screw type dehydrator 9 for dehydration. The dehydrator 9 has a screw diameter of 9o.
Crane φ x 216 Dragon φ, screw tip 9' side has an inclination angle of 10
It was operated at a screw rotation speed of 60 rpm.

Most of the water in the latex was liberated at the inlet of the dehydrator 9, and brown wastewater 1o was separated from the drain outlet at a flow rate of 24.1 kg/Hr. There was no loss of polymer into the separated wastewater.

The polymer solution was cut into small pieces by the tip 9' of the dehydrator 9 and fed to the vent extruder 11 to remove the solvent. The vent extruder 11 used had a screw diameter of 65 mm,
The screw was operated at 1100 rpm with the specifications of a single-shaft three-stage vent (the first vent also serves as a feeder) with L/D = 30. Also, the heating jacket is Fiedro 150.
℃, set the temperature from the second vent to the tip to 220℃,
The dice are set at 230℃ and the first Ghent 400To
rr, 2nd Ghent 50Torr, 3rd Ghent 30Torr
The pressure was reduced using a vacuum pump to rr. The resin was extruded using a strand from a die at the tip of the extruder, and the resin was cut and collected as pellets.

Table 1 shows the residual volatile content and physical properties of the recovered resin.

The physical properties were measured by the following method.

The impact strength was measured by molding a test piece from the above pellet at 220°C using a 5-ounce injection molding machine and at a temperature of 23°C according to ASTM-D256.

! Glossiness and whiteness measurements were made on the above specimens molded at 220°C using a 5-ounce injection molding machine, and whiteness measurements were made on specimens molded after residence in a cylinder for 15 minutes at a temperature of 280°C. , respectively ASTM-D
Measured according to 523.

Example-2 Using the same raw materials and the same equipment as Example-1, the mixing ratio of ABS resin latex and As resin solution was changed so that the rubber content in the blend (solid content) was 10 parts. We conducted an experiment. The operating conditions are ABS latex supply amount of 2
5kg/f(r, the supply amount of As resin solution is 74kg/f)
Hr, supply amount of 10% magnesium sulfate aqueous solution 1.8
kg/Hr, and all other conditions were as in Example-1.
It was made the same as.

Separation of water in the latex and devolatilization in the vented extruder were also very good as in Example-1.

Table 1 shows the residual volatile content and physical properties of the recovered resin.

Physical properties were measured in the same manner as in Example-1.

Comparative Examples-1 and 2 Using the ABS resin latex (A) and the As resin solution (B) polymerized in Example-1, BS resin and AS resin were recovered by the conventional method, and then Example- Tri-blending was performed to obtain the same rubber content as those recovered in Example 1 and Example 2, and the pellets were made into pellets.

That is, 2 parts of magnesium sulfate was added to 100 parts (solid content) of the ABS resin latex of (A), solidified at 90°C, the resulting slurry was dehydrated using a centrifugal dehydrator, and then dried for 60 min using a hot air dryer. ABS after drying for 12 hours at ℃
A dry resin powder was obtained. On the other hand, (B) As resin solution (65
``I 211113 stage'' extruder to remove solvent.
An AS resin pellet was obtained from the tip. Then, BS dry powder and As pellets were blended into this at a ratio of 1:2 and 1:5 so that the rubber content was 20 parts and 10 parts, respectively, as in Example-1 and Example-2. It was pelletized using a vent extruder.

Table 1 shows the residual volatile content and physical properties of the obtained pellets.

Comparing the pellets obtained in Examples 1 and 2 and Comparative Examples 1 and 2, it was found that the pellets according to the present invention had lower residual volatile matter, better color tone, and higher impact strength. It is clear that the process of the present invention is significantly simplified compared to the conventional method.

Example 3 An experiment was conducted using a rubber-containing FF 140 parts emulsion graft polymer latex polymerized by the following polymerization process and a thermoplastic resin solution polymerized in (Ij) of Example 1.

(Latex polymerization prescription) Polybutadiene latex (solid content) 40 parts styrene
21 Acrylonitrile 9 Tertiary dodecyl mercapcun 0.20 Potassium dinate 1.0 Potassium hydroxide 0.03 Water (including water in latex) 120 The above mixture was charged into a reactor equipped with a heating jacket and a stirrer, and nitrogen After replacing the internal air with
Sodium pyrophosphate dissolved in 10 parts of water heated to 0.
3 parts, dextrose 0.3 parts, ferrous sulfate 0.006
1 part and 0.1 part of cumene hydroperoxide were added and reacted. One hour after starting the reaction, the following mixture was added continuously over 2 hours, and the polymerization rate was 98.9%.
A graft polymer latex was obtained.

Styrene 21 parts Acrylonitrile 9 Tertiary dodecyl mercaptan 0.050 Potassium dinate 1.0 Potassium hydroxide 0.03 Cumene hydrobarobocide 0.1 Water 40 After the reaction, an anti-aging agent is added to the latex to give 2.6
0.5 part of -di-tert-butyl para-cresol was added.

In Example-3, in the process shown in FIG. 1, a vent extruder 21 having a dehydration function with a slit barrel shown in FIG. 3 was used in place of the dehydrator 9 and vent extrusion fil+, and the other steps were as in Example-1. The experiment was conducted using the same equipment.

That is, in the same manner as in Example-1, the AS resin solution was
g/Hr, 7 kg/Hr of 10% magnesium sulfate aqueous solution.
After being mixed in the mixer 7, 44 L of the mixture was supplied to the mixer 8. On the other hand, the ABS resin latex obtained in the above polymerization was supplied to the mixer 8 at a supply rate of 92 kg/Hr, and mixed with the AS resin solution. Mixer 8 is Example-1
I drove under the same conditions.

Next, the mixed solution at the outlet of the mixer 8 was supplied to a vent extruder 21 with a slit barrel to perform dehydration and solvent removal.

The vent extruder 21 with slit barrel has a screw diameter of 65
A Ryu φ two-screw three-stage vented extruder with L/D=40 was used. The barrel of the extruder is divided into five parts as shown in Fig. 3, and the first barrel is provided with a slit 23 for discharging the water squeezed out by the feed flow 22 south and the screw compression, and the second barrel is provided toward the tip. , the third and fourth barrels each have one vent 24, 25, 26,
Only the fifth barrel 27 is uniaxial in order to provide the pumping ability. The second to fifth barrels had heating jackets, and the temperature was set at 220'C, and the temperature of the die at the tip of the extruder was set at 230'C. In addition, each vent is depressurized using a vacuum pump, and the pressure inside the first vent is 40.
0 Torr, 2nd internal pressure 50 Torr, 3rd
It was operated at an internal pressure of 30 Torr. The extruder screw is operated at 12 Orpm, brown water is separated from the slit 23 at a rate of 60 kg/Hr, and the resin is extruded into strands from the die at the tip of the extruder at a speed of 70 kg/Hr, which is cutty-sung and made into pellets. A rubber-modified thermoplastic resin was recovered. Table 1 shows the residual volatile content and physical properties of the recovered resin.

Comparative Example-3 Comparative Example-3 by conventional method using the same raw materials as Example-3
After recovering ABS resin dry powder and AS pellets under the same conditions as in Example 1, dry blending was performed to obtain the same rubber content as that recovered in Example 3 to ABS: 8 S = 1: 1, and a screw diameter of 40 mm was obtained. It was pelletized using a vented extruder.

Table 1 shows the residual volatile content and physical properties of the obtained pellets.

Comparing the pellets obtained in Example 3 and Comparative Example 3, it is clear that the pellets according to the present invention have lower residual volatile content, better color tone, higher impact resistance, and superior quality. It is also clear that the process of the present invention is significantly simpler than the conventional method.

Comparative Example-4 Mixer 8 was prepared using the same raw materials and the same equipment as Example-1.
The experiment was conducted by changing only the shear rate.

The experiment was conducted under the same conditions as in Example-1 except that the shear rate of the mixer 8 was lowered to 50 to 901/sec. As a result, the polymer solution coming out of the mixing R8 was non-uniform and contained hard lumps, and the free water contained fine particles, which leaked through the slits of the dehydrator 9.

Furthermore, hard lumps accumulated at the discharge port of the mixer 8, and the mixer became almost clogged in about 30 minutes, making it impossible to operate.

As mentioned above, the shear rate of the mixer is limited to 10 in the present invention.
If it is smaller than 0.01/sec, polymer will be lost and stable operation for a long time will not be possible.

[Brief explanation of the drawing]

FIG. 1 shows a typical process for recovering polymer according to the method of the present invention. FIG. 2 is an example of the mixer 8 used in the example, and FIG. 3 is a schematic diagram of a vent extruder with a dehydration function used in the third example. 1... Thermoplastic resin solution storage tank, 2... Coagulant storage tank, 3... Graft polymer latex storage tank, 4.5.6.
... Pump, 7.8... Mixer, 9... Dehydrator,
10...Drainage, 11...Screw type vent extruder, 12...
- Condenser, 13... Vacuum pump, 14... Condensate, 15... Product, 16... Fixed ring, 17...
Rotating blade, 1B...Liquid inlet, 19...Liquid outlet, 20
... Drive motor, 21... Vent extruder with dehydration function, 22...
Feedro, 23...Slit, 24.25.26
...Bent, 27...5th barrel.

Claims (2)

[Claims] (1) Graft copolymer latex to graft copolymer latex
In the method for recovering the polymer, a graft polymer latex having a rubber content of 30 to 80% by weight obtained by graft polymerizing a vinyl monomer in the presence of a fal rubber-like polymer latex, (bl a vinyl-based A thermoplastic resin solution obtained by solution polymerization or bulk polymerization of a monomer in an organic solvent and a TC+ coagulant aqueous solution were heated at a shear rate of 1001/sec.
that's all. A method for recovering a rubber-modified thermoplastic resin having a rubber content of 5 to 60% by weight. (2) The method according to claim (1), wherein the method for recovering the thermoplastic resin comprises removing the liquid by mechanical squeezing and then separating the remaining volatile components by an evaporation method.