Method for producing thermoplastic resins

Emulsion polymerization type thermoplastic resin of high performance can be produced by the following methods: namely, a method which comprises removing an aqueous phase from a two-phase mixture comprising a latex of polymer (1) produced by emulsion polymerization, a water soluble agent (2) in an amount of 10% by weight or less of said polymer (1) which is capable of coagulating the latex of polymer (1) and an organic agent (3) in an amount of 0.1 to 6 times the weight of said polymer (1) which is capable of dissolving both an uncrosslinked polymer contained in said polymer (1) and thermoplastic polymer (4) mentioned hereinbelow and has a solubility in water of 5% by weight or less at 25.degree. C., then melt-mixing molten polymer which has been subjected to a first devolatilization by a thermal means with thermoplastic resin (4) and then subjecting the mixture to a second devolatilization; and a method which comprises removing an aqueous phase from a two-phase mixture comprising a latex of polymer (1) produced by emulsion polymerization, a water soluble agent ( 2) in an amount of 10% by weight or less of said polymer (1) which is capable of coagulating the latex of polymer (1) and an organic agent (3) in an amount of 0.1 to 6 times the weight of said polymer (1) which is capable of dissolving an uncrosslinked polymer contained in said polymer (1) and has a solubility in water of 5% by weight or less at 25.degree. C. and then melt-mixing the molten polymer from which volatile component has been devolatilized by a thermal means with thermoplastic polymer (4').

This invention relates to a method for producing a thermoplastic resin of 
high performance by mixing a polymer prepared by emulsion polymerization 
and other thermoplastic polymer characterized in that the polymer is 
efficiently extracted with an organic agent and a water soluble agent 
capable of coagulating the polymer contained in emulsion polymer latex. 
Emulsion polymerization is a very useful process for production of resins 
having high functions, but is inferior to bulk polymerization and 
suspension polymerization in production cost, disposal of waste water, 
etc. 
Therefore, usually, a polymer prepared by emulsion polymerization in a 
possible minimum amount is mixed with a polymer prepared by a process 
other than the emulsion polymerization to produce a resin having high 
function as a whole. 
Generally, most of the rubber modified thermoplastic resins represented by 
ABS resins are those obtained by mixing and kneading a polymer obtained by 
graft polymerization of a vinyl monomer on a rubber latex and a 
thermoplastic resin. Usually, production of them comprises the steps of 
emulsion polymerization, coagulation, solidifying, dehydration, drying, 
blending, and melt extrusion. The emulsion polymerization step is a step 
of producing a polymer latex by emulsion polymerizing or emulsion graft 
polymerizing an acrylic monomer, vinyl cyanide monomer, vinyl aromatic 
monomer, a diene rubber latex, vinyl rubber latex, natural rubber latex, 
silicone rubber latex and the like. The coagulation and solidifying steps 
are steps of adding a coagulant such as polyvalent salts and acids to the 
polymer latex to destroy the emulsion state and coagulate the polymer and 
solidifying the polymer into rigid powders. The dehydration and drying 
steps are steps of removing the aqueous phase from the mixture of the 
powdered polymer and water by a means such as centrifugal dehydration or 
the like and further drying the powders by a means such as flow drying 
method to obtain dry powders. The blending step is a step of blending said 
dry powders with other thermoplastic resins and additives such as 
stabilizer, lubricant, polasticizer, etc. The melt extrusion step is a 
step of melting, kneading and extruding the blend materials into strands 
by screw extruder and pelletizing them. 
One of the problems in production brought about in the above method of 
producing thermoplastic resins comprising the above steps including 
emulsion polymerization is firstly that much heat is required. This is 
because of the use of a large quantity of hot-air at the drying step. 
Some proposals have been made to improve the conventional methods of 
production of thermoplastic resins which have problems leading to 
reduction of industrial competitiveness and some of them have been 
industrially practised. One of them has aimed at reduction of heat used at 
the drying step and utilized a screw extruder generally called a 
dehydration extruder which has a dehydration function. The proposed 
methods of this type are roughly classified into those according to which 
the blend of the wet polymer powders after subjected to coagulation, 
solidification and dehydration and other thermoplastic resins and 
additives or the wet polymer powders alone is fed to said dehydration 
extruder and those according to which polymer latex and coagulant together 
with other thermoplastic resins and additives, if necessary, are fed to 
said dehydration extruder. 
According to these methods the reduction of the heat used can be expected 
because the drying step at which a large quantity of hot air is used is 
omitted. However, the former method has the problems that continuous 
operation is difficult because polymer fine powder clogs in aperture 
provided at a barrel when water contained in the wet polymer powder is 
removed by a dehydration mechanism and is discharged from said aperture 
and/or barrel and screw wears out due to compression of unmelted powder 
for removal of water and furthermore apparatuses made of special materials 
are required. Besides, generally, 20-30% by weight (dry base) of water 
contained in the starting materials remains without being removed as 
droplet and this remaining water must be evaporated and removed at a vent 
portion provided in the dehydration extruder by a thermal means. Thus, 
heat load of the dehydration extruder increases to cause reduction of 
treating capacity of the extruder. 
On the other hand, according to the latter method where polymer latex and 
coagulant are fed to dehydration extruder, water is removed at the step of 
heating and solidifying a creamy mixture of the latex and the coagulant 
and is discharged from anaperture provided at the barrel. The shape of 
polymer particles formed according to this method is very unstable and 
leakage of polymer from the aperture, clogging of the aperture and wearing 
out of compression parts are severer than the former method which uses wet 
polymer powder. Thus, this method has not yet been practically employed. 
As mentioned above, many proposals have been made for production of 
emulsion polymerization type thermoplastic resins. However, at present, 
there have not yet been provided such methods according to which the 
reduction of heat required at production step of resins can be attained 
and the desired resins of high quality and high competitivieness can be 
obtained. Under the circumstances, this invention provides a most highly 
rationalized method of production of emulsion polymerization type 
thermoplastic resins with saving of energy. 
The first method of this invention is a method for producing a 
thermoplastic resin which comprises removing an aqueous phase from a 
two-phase mixture comprising a latex of polymer (1) produced by emulsion 
polymerization, a water soluble agent (2) in an amount of 10% by weight or 
less of said polymer (1) which is capable of coagulating the latex of 
polymer (1) and an organic agent (3) in an amount of 0.1 to 6 times the 
weight of said polymer (1) which is capable of dissolving both an 
uncrosslinked polymer contained in said polymer (1) and thermoplastic 
polymer (4) mentioned hereinbelow and has a solubility in water of 5% by 
weight or less at 25.degree. C., then melt-mixing molten polymer which has 
been subjected to a first devolatilization by a thermal means with 
thermoplastic polymer (4) and then subjecting the mixture to a second 
devolatilization. 
The second method of this invention is a method for producing a 
thermoplastic resin which comprises removing an aqueous phase from a 
two-phase mixture comprising a latex of polymer (1) produced by emulsion 
polymerization, a water soluble agent (2) in an amount of 10% by weight or 
less of said polymer (1) which is capable of coagulating the latex of 
polymer (1) and an organic agent (3) in an amount of 0.1 to 6 times the 
weight of said polymer (1) which is capable of dissolving an uncrosslinked 
polymer contained in said polymer (1) and has a solubility in water of 5% 
by weight or less at 25.degree. C. and then melt-mixing the molten polymer 
from which volatile component has been devolatilized by a thermal means 
with thermoplastic polymer (4'). This thermoplastic resin (4') is not 
necessarily soluble in the organic agent (3). 
This invention is especially useful in production of a rubber modified 
thermoplastic resin by graft polymerization of a glassy polymer on a 
rubber-like polymer to impart functions. In this case, the rubber polymer 
latexes usable include all of those which have been used as raw materials 
for rubber modified thermoplastic resins. As examples thereof, mention may 
be made of latexes of diene rubbers such as polybutadiene, polyisoprene, 
SBR, etc., those of olefin rubbers such as ethylene-propylene rubber, 
ethylene-vinyl acetate rubber, etc., those of acrylic rubbers such as 
polyethyl acrylate, polybutyl acrylate, etc., those of silicone rubbers 
such as polydimethylsiloxane, etc. These rubber polymer latexes may not 
necessarily be used in this invention, but they may be used singly or in 
combination of two or more. 
Vinyl monomers are used for emulsion polymerization carried out in the 
presence or absence of these rubber polymers because the polymerization 
method is radical polymerization and it is common to choose the optimum 
vinyl monomers considering compatibility and adhesion with the 
thermoplastic polymers to be blended. The same thing can be applied to 
this invention. Thus, the vinyl monomers usable in this invention include 
those which have been hitherto used, namely, vinyl cyanide monomers such 
as acrylonitrile, methacrylonitrile, etc., vinyl aromatic monomers such as 
styrene, .alpha.-methyl styrene, etc., methacrylates such as methyl 
methacrylate, phenyl methacrylate, etc., halogenated vinyl monomers such 
as methyl chloroacrylate, 2-chloroethyl methacrylate, etc. and other 
radical polymerizable monomers. These monomers may be used alone or in 
combination of two or more. Vinyl cyanide monomers, vinyl aromatic 
monomers and methacrylate monomers are preferred in this invention. 
It is necessary in this invention to mix the latex of polymer (1) obtained 
by emulsion polymerization with organic agent (3) and water soluble agent 
(2) having coagulating ability. This operation is inherent in this 
invention. 
The organic agents (3) used in this invention are those which have a 
solubility in water of 5% by weight or less, preferably 2% by weight or 
less at 25.degree. C., namely, which cannot be contained in an amount of 
more than 5 g, preferably more than 2 g in 100 g of aqueous solution at 
25.degree. C. and which can dissolve uncrosslinked polymer contained in 
polymer (1) obtained by emulsion polymerization and thermoplastic polymer 
(4). This organic agent can be used in an amount of 0.1-6 times, 
preferably 0.2-2 times the weight of polymer (1) obtained by emulsion 
polymerization. 
When the solubility of the organic agent in water at 25.degree. C. is more 
than 5% by weight, the aqueous phase of the two phases separated in the 
mixture becomes cloudy. 
When amount of the organic agent (3) is less than 0.1 time the weight of 
polymer (1) the effect aimed at in this invention cannot be developed. On 
the other hand, when the organic agent (3) is used in an amount of more 
than 6 times the polymer (1), a large quantity of heat is required for 
removal of the organic agent. These are not preferred from the industrial 
viewpoint. 
As examples of the organic agents (3) used in this invention, mention may 
be made of non-polymerizable organic agents such as petroleum ether, 
benzene, toluene, xylene, ethylbenzene, diethylbenzene, p-cymene, 
tetralin, methylene chloride, chloroform, carbon tetrachloride, trichlene, 
chlorobenzene, epichlorohydrin, methyl-n-propyl ketone, acetophenone, 
n-propyl acetate, n-butyl acetate, 1-nitropropane, etc. and polymerizable 
organic agents such as styrene, methyl methacrylate, 
.alpha.-methylstyrene, etc. These are mere examples and this invention is 
never limited to these examples and any organic agents which satisfy the 
above conditions may be used sinly or in combination of two or more. 
The water soluble agents (2) having coagulating ability used in this 
invention include any materials which are water soluble and have an 
ability to coagulate the latex of polymer (1) used and may be used in an 
amount of 10% by weight or less, preferably 3% by weight or less of said 
polymer (1) for not causing deterioration of quality of resins to be 
produced. Generally, the water soluble agent (2) is used in an amount of 
at least 0.2% by weight. As examples of these materials, mentioned may be 
made of salts of polyvalent metals such as aluminum sulfate, aluminum 
chloride, aluminum nitrate, magnesium sulfate, calcium chloride, calcium 
nitrate, etc., inorganic acids such as sulfuric acid, hydrochloric acid, 
nitric acid, etc. and organic acids such as acetic acid, propionic acid, 
etc. These may be used singly or in combination of two or more. In this 
invention, preferred are salts of polyvalent metals and inorganic acid. 
According to this invention, when latex of polymer (1), the organic agent 
(3) and the water soluble agent (2) having coagulating ability are mixed, 
the mixture separates into an organic phase composed of polymer (1), the 
organic agent (3), a slight amount of a polymerization assistant soluble 
in said organic agent, etc. and an aqueous phase composed of the water 
soluble agent (2), water, a slight amount of a water soluble 
polymerization assistant, etc. 
At this time, the organic phase changes to a highly viscous state and is 
completely separated from the aqueous phase and so removal and discharging 
of the aqueous phase can be easily accomplished; wearing out of apparatus 
due to compression of solid power can be avoided; and evaporation latent 
heat of the organic agent is small and generally the heat load to the 
extruder is 3-15% by weight (dry base) in terms of water for the polymer 
produced by emulsion polymerization to make it possible to hold down the 
reduction of capacity of the extruder the minimum. In these respects, this 
invention is superior to the above-mentioned method of using a dehydration 
extruder. 
The aqueous phase and the organic phase are separated from the two-phase 
mixture by conventional means such as decantation, centrifugal 
dehydration, compression dehydration, etc. to obtain the organic phase 
mainly composed of polymer (1) and organic agent (3). In the first method, 
a part of said organic agent (3) and a slight amount of remaining water 
are removed by conventional devolatilization means and the remainder was 
melt-mixed with another thermoplastic polymer (4) in the presence of 
remaining organic agent (3). Then said remaining organic agent (3) is 
removed by conventional devolatilization means whereby the desired 
thermoplastic resin of high performance can be produced in a high 
efficiency and in a rationalized manner. In the second method, a whole of 
organic agent and a slight amount of remaining water included in said 
organic phase are removed by conventional devolatilization means and the 
remainder was melt-mixed with another thermoplastic polymer (4') whereby 
the desired thermoplastic resin of high performance can be produced in a 
high efficiency and in a rationalized manner. 
Thermoplastic polymer (4) and thermoplastic polymer (4') include various 
general-purpose resins, engineering resins, etc. and as typical examples 
thereof, mention may be made of acrylonitrile-styrene copolymers, 
acrylonitrile-.alpha.-methylstyrene copolymers, 
acrylonitrile-.alpha.-methylstyrene-N-phenylmaleimide copolymers, 
polystyrene, polymethyl methacrylate, polyvinyl chloride, polycarbonate, 
polysulfone, polyethylene terephthalate, polytetramethylene terephthalate, 
etc. 
These thermoplastic polymers (4) and thermoplastic polymer (4') may be used 
singly or in combination of two or more. In this invention, 
acrylonitrile-styrene copolymers, polycarbonate, polyvinyl chloride, 
polysulfone, etc. are preferred. 
The thermoplastic polymers used in this invention are never limited to 
those enumerated above and there may be used any polymers which are 
capable of being molten with heat, but in many cases, melt viscosity of 
the thermoplastic polymers used is different from that of the polymers 
produced by emusion polymerization and melt-mixing of the polymers greatly 
different in melt viscosity requires a large power. On the other hand, in 
the presence of an organic agent capable of dissolving the polymers, 
mixing of even such polymers greatly different in melt viscosity is very 
easy because the polymers have solution-like property. Therefore, the 
first method of this invention is conspicuously advantageous when 
thermoplastic resin (4) and polymer (1) produced by emulsion 
polymerization are different in their melt viscosity. Furthermore, the 
thermoplastic polymer to be mixed also contains a slight amount of 
volatile matters such as water, volatile polymerization assistant, 
remaining monomers, etc. and it is preferred from the viewpoint of quality 
of products to remove these matters as much as possible. 
The first method of this invention is very useful as a means to mix a 
polymer produced by emulsion polymerization with a thermoplastic polymer 
having a melt viscosity different from that of said polymer and remove the 
unnecessary volatile matters which may bring about deterioration of 
properties of products. Furthermore, when there are no difficulties in 
mixing which may be caused by the difference in melt viscosity, this 
invention is also useful in improvement of quality of products, but the 
greatest advantage is in providing a method for producing a thermoplastic 
resin from a latex of emulsion polymer at low cost and in a rationalized 
manner.

The following examples and reference examples illustrate the method of this 
invention and effects attained by this invention. The parts in these 
examples and reference examples are all by weight. 
EXAMPLE 1 
Acrylonitrile and styrene were graft polymerized on polybutadiene latex of 
0.36 .mu.m in average particle diameter in accordance with the formulation 
of Table 1 to obtain a latex of graft rubber polymer. 
TABLE 1 
______________________________________ 
Polybutadiene latex 114.3 parts 
(polybutadiene 40 parts) 
Acrylonitrile 15 parts 
Styrene 45 parts 
Sodium laurate 0.5 part 
Sodium hydroxide 0.01 part 
Rongalite 0.2 part 
Ferrous sulfate 0.002 part 
EDTA-di-sodium salt 0.1 part 
Tertiary-butyl hydroperoxide 
0.3 part 
Lauryl mercaptan 0.6 part 
Deionized water 125 parts 
Polymerization temperature 
70.degree. 
C. 
Polymerization time 240 minutes 
______________________________________ 
An acrylonitrile-styrene copolymer as a thermoplastic polymer was prepared 
in accordance with the formulation of Table 2. 
TABLE 2 
______________________________________ 
Acrylonitrile 25 parts 
Styrene 75 parts 
Azobisisobutyronitrile 0.3 part 
Lauryl mercaptan 0.5 part 
POVAL (polyvinyl alcohol, poly- 
0.07 part 
metization degree 900) 
Sodium sulfate 0.3 part 
Water 250 parts 
Polymerization temperature 
75.degree. 
C. 
Polymerization time 240 minutes 
______________________________________ 
After completion of polymerization, the resultant suspension of 
acrylonitrile-styrene copolymer was subjected to centrifugal dehydration 
and dried at 80.degree. C. to obtain a powder of said copolymer. 
Then, 300 parts of said latex of graft rubber polymer, 50 parts of toluene, 
1000 parts of 0.1 wt. % aqueous dilute sulfuric acid solution, 0.1% by 
weight (based on the weight of all the polymers) of Irganox 1076 (trade 
mark for aging resister of Ciba-Geigy Co.) and 0.5% by weight (based on 
the weight of all the polymers) of Armide HT (trade mark for molding 
assistant of Lion Armour Co.) were mixed to obtain a mixture which 
separated into an aqueous phase and a high viscous organic phase. The 
organic phase was taken out and passed through two press rolls to remove 
superfluous aqueous phase. The organic phase was fed from a first feed 
opening of an extruder having two feed openings and two vent holes and 
having no kneading mechanism. A part of toluene contained in the polymer 
was devolatilized from the first vent holes, 150 parts of said copolymer 
was fed from the second feed opening provided just behind the first vent 
hole, the remaining toluene was devolatilized from the second vent hole 
provided down the second feed opening and the polymer was molded into 
pellets. The proportion of amounts of toluene devolatilized from the first 
vent hole and the second vent hole was about 3:2. Thus obtained pellets 
had a smooth surface and had no inhomogeneous portions called "fish eyes". 
These pellets were injection molded to make test pieces and properties 
thereof were measured to obtain the results as shown in Table 3. These 
results show the superiority of the rubber modified thermoplastic resin 
obtained in this Example. 
TABLE 3 
______________________________________ 
Item Test methods* Results 
______________________________________ 
Tensile yield 
ASTM D-638 500 kg/cm.sup.2 
strength (at 20.degree. C.) 
Izod impact 
ASTM D-256 
strength (at 20.degree. C., 1/4", notched) 
32 kg cm/cm 
(at 0.degree. C., 1/4", notched) 
25 kg cm/cm 
Rockwell ASTM D-785 (R scale) 
110 
hardness 
Melt flow rate 
ASTM D-1238 2.2 g/10 min 
(at 200.degree. C., 5 kg) 
______________________________________ 
*Same in the following Examples 2, 5-7 and 9 and Reference Example 
EXAMPLE 2 
A latex of graft rubber polymer was prepared using the same agents as in 
Example 1 in accordance with the formulation of Table 4. 
TABLE 4 
______________________________________ 
Polybutadiene latex 168 parts 
(Polybutadiene 60 parts) 
Acrylonitrile 11 parts 
Styrene 29 parts 
Sodium laurate 0.4 part 
Sodium hydroxide 0.01 part 
Rongalite 0.15 part 
Ferrous sulfate 0.001 part 
EDTA-di-sodium salt 0.05 part 
Tertiary-butyl peroxide 
0.2 part 
Luaryl mercaptan 0.3 part 
Deionized water 50 parts 
Polymerization temperature 
70.degree. 
C. 
Polymerization time 280 minutes 
______________________________________ 
When 75 parts of thus obtained latex of graft rubber polymer, 25 parts of 
ethylbenzene and 40 parts of 1 wt. % aluminum sulfate were continuously 
mixed by a continuous type kneader, the resulting mixture separated into 
two phase as in Example, 1. This was continuously fed to an extruder 
having successively a first feed opening, a dehydrating part, a first 
devolatilizing part, a second feed opening and a second devolatilizing 
part and after dehydration and the first devolatilization, 71 parts of the 
acrylonitrile-styrene copolymer used in Example 1 was fed from the second 
feed opening and then the second devolatilization was carried out. The 
mixture was molded into pellets. The proportion of amounts of ethylbenzene 
devolatilized at the first stage and at the second stage was about 9:1. 
The surface of the pellets obtained was smooth and there were no fish 
eyes. These pellets were injection molded to make test pieces and 
properties thereof were measured to obtain the results as shown in Table 
5. These results indicate that the rubber modified thermoplastic resin 
obtained in this Example was superior. 
TABLE 5 
______________________________________ 
Items Results 
______________________________________ 
Tensile yield strength 
475 Kg/cm.sup.2 
Izod impact strength 
35 Kg cm/cm (at 20.degree. C.) 
" 28 Kg cm/cm (at 0.degree. C.) 
Rockwell hardness 
106 
Melt flow rate 1.9 g/10 min. 
______________________________________ 
EXAMPLE 3 
Methyl methacrylate and methyl acrylate were graft polymerized on SBR 
rubber latex of 0.14 .mu.m in average particle diameter in accordance with 
the formulation of Table 6 to obtain a latex of graft rubber polymer. 
TABLE 6 
______________________________________ 
SBR rubber latex 100 parts 
(SBR rubber 50 parts) 
Methyl methacrylate 45 parts 
Methyl acrylate 5 parts 
Potassium rosinate 1 part 
Rongalite 0.2 part 
Ferrous sulfate 0.003 part 
EDTA-di-sodium salt 0.1 part 
Cumene hydroperoxide 0.4 part 
Octyl mercaptan 0.2 part 
Deionized water 150 parts 
Polymerization temperature 
65.degree. 
C. 
Polymerization time 240 minutes 
______________________________________ 
Polymethyl methacrylate as a thermoplastic polymer was produced in 
accordance with the formulation of Table 7. 
TABLE 7 
______________________________________ 
Methyl methacrylate 100 parts 
Azobisisobutyronitrile 0.3 part 
Lauryl mercaptan 0.5 part 
Poval (Polyvinyl alcohol, poly- 
0.07 part 
merization degree 900) 
Sodium sulfate 0.25 part 
Water 200 parts 
Polymerization temperature 
80.degree. 
C. 
Polymerization time 180 minutes 
______________________________________ 
After completion of polymerization, the obtained suspension of polymethyl 
methacrylate was subjected to centrifugal dehydration and dried at 
80.degree. C. to obtain a powder of the polymer. 
Then, 90 parts of said latex of graft polymer, 100 parts of chloroform and 
300 parts of a 0.5 wt. % dilute aqueous magnesium sulfate solution were 
continuously mixed by a continuous type kneader to obtain a mixture which 
separated into an aqueous phase and a high viscous organic phase. This 
mixture was subjected to removal of the aqueous phase and the first 
devolatilization of chloroform in the same apparatus as used in Example 2 
and successively 70 parts of said polymethyl methacrylate was continuously 
fed from the resin feed opening provided in this apparatus to melt-mix 
with the graft polymer and further the second devolatilization was carried 
out. Then, the mixture was pelletized. Thus obtained pellets had a smooth 
surface and had no fish eyes. These pellets were injection molded to make 
test pieces and properties thereof were measured to obtain the results as 
shown in Table 8. These results indicate the superiority of the rubber 
modified thermoplastic resin produced in this Example. 
TABLE 8 
______________________________________ 
Items Test methods* 
Results 
______________________________________ 
Total light transmission 
ASTM D-1003 90% 
Dynstat impact strength 
DIN 53453 19 Kg cm/cm 
Rockwell hardness 
ASTM D-785 77 
(M scale) 
______________________________________ 
*Same test methods were used in Example 8, too. 
EXAMPLE 4 
Acrylonitrile and .alpha.-methylstyrene were emulsion polymerized in 
accordance with the formulation of Table 9 to obtain a latex of polymer. 
TABLE 9 
______________________________________ 
Acrylonitrile 25 parts 
.alpha.-Methylstyrene 75 parts 
Potassium persulfate 0.5 part 
Sodium bicarbonate 0.2 part 
Sodium laurate 1.8 part 
t-Dodecyl mercaptan 0.5 part 
Deionized water 180 parts 
Polymerization temperature 
65.degree. 
C. 
Polymerization time 240 minutes 
______________________________________ 
140 parts of thus obtained latex, 100 parts of a 1 wt. % aqueous sulfuric 
acid solution and 10 parts of toluene were continuously fed to an 
apparatus having successively a feed opening for the polymer latex, 
aqueous sulfuric acid solution and toluene, a mixing part, a dehydrating 
part, a first devolatilizing part, a feed opening for resin and a second 
deveolatilizing part and water separated in the apparatus was discharged 
from the dehydrating part. Then, about 50% by weight of the volatile 
components mainly composed of toluene were devolatilized from the first 
devolatilizing part by heating. Thereafter, 50 parts of the same 
acrylonitrile-styrene copolymer as used in Example 1 was continuously fed 
from the resin feed opening provided down the first devolatilizing part to 
mix with the acrylonitrile-methylstyrene copolymer. Then, toluene 
remaining in thus obtained thermoplastic resin mixture was devolatilized 
from the second devolatilizing part and thereafter, the resin mixture was 
extruded from the apparatus into strands, which were pelletized. After 
drying, the pellets were injection molded into a transparent sheet of 3 mm 
thick. Vicat softening point (load 5 Kg) of this sheet according to ISO 
R-306 was measured to obtain 119.degree. C. Rockwell hardness HRM of the 
sheet was 93. These results show that the thermoplastic resin produced in 
this Example was excellent as a heat resistant resin. 
EXAMPLE 5 
A thermoplastic resin was obtained in the same manner as in Example 1 
except that a polycarbonate (Novalex 7022 manufactured by Mitsubishi 
Chemical Industries Ltd.) was used in place of the acrylonitrile-styrene 
copolymer. Thus obtained resin was homogeneous and had no fish eyes. 
Properties of the resin are shown in Table 10. 
TABLE 10 
______________________________________ 
Items Test method Results 
______________________________________ 
Tensile yield strength 
ASTM D-638 (at 20.degree. C.) 
460 Kg/cm.sup.2 
Izod impact strength 
ASTM D-256 52 Kg cm/cm 
(at 20.degree. C., 1/4", notched) 
Rockwell hardness 
ASTM D-785 111 
(R scale) 
Melt flow rate 
ASTM D-1238 0.2 g/10 min 
(at 200.degree. C., 5 Kg) 
______________________________________ 
REFERENCE EXAMPLE 
The emulsion polymerization latex used in Example 1 was coagulated with 
sulfuric acid by a conventional method, dehydrated and dried to obtain a 
dry powder. This was mixed with the same polycarbonate as used in Example 
5 and other assistants at the same ratio as in Example 1. Strands were 
produced from the mixture at the same temperature and the same 
devolatilizing conditions using the same extruder as used in Example 1 
except that nothing was fed from the second feed opening. Thus obtained 
strands were inhomogeneous and it appeared that mixing or kneading of the 
polymer obtained by emulsion polymerization and the polycarbonate was 
insufficient. 
EXAMPLE 6 
When 300 parts of the same latex of graft polymer as in Example 1, 50 parts 
of toluene, 1000 parts of a 0.1 wt. % dilute aqueous sulfuric acid 
solution and 0.1% by weight (based on all the polymers) of Irganox 1076 
and 0.5% by weight (based on all the polymers) of Armide HT were mixed, 
the resulting mixture separated into an aqueous phase and a high viscous 
organic phase. The organic phase was taken out and passed through two 
press rolls to remove remaining aqueous phase, toluene contained in the 
high viscous organic phase was devolatilized by a vented extruder and 150 
parts of the same acrylonitrile copolymer powder as in Example 1 was fed 
and then the polymer was molded into pellets. These pellets had a smooth 
surface and had no fish eyes. These were injection molded to make test 
pieces and properties thereof were measured to obtain the results as shown 
in Table 11. These results show the superiority of the rubber modified 
thermoplastic resin produced in this Example. 
TABLE 11 
______________________________________ 
Items Results 
______________________________________ 
Tensile yield strength 
485 Kg/cm.sup.2 
Izod impact strength 
31 Kg cm/cm 
(at 20.degree. C.) 
" 24 Kg cm/cm 
(at 0.degree. C.) 
Rockwell hardness 109 
Melt flow rate 2.2 g/10 min. 
______________________________________ 
EXAMPLE 7 
When 75 parts of the same graft rubber latex as in Example 2, 25 parts of 
ethylbenzene and 40 parts of a 1 wt. % aluminum sulfate were continuously 
mixed by a continuous kneader, the resulting mixture separated into two 
phases as in Example 6. This was continuously fed to an extruder having a 
dehydrating mechanism and was subjected to dehydration and 
devolatilization and thereafter, 71 parts of the acrylonitrile-styrene 
copolymer used in Example 1 was fed from a resin feed opening provided at 
this extruder and the mixture was molded into pellets. Thus obtained 
pellets had a smooth surface and had no fish eyes. These were injection 
molded to make test pieces and properties thereof were measured in the 
same manner as in Example 1 to obtain the results as shown in Table 12. 
These results indicate that the rubber modified thermoplastic resin 
produced in this Example was superior. 
TABLE 12 
______________________________________ 
Items Results 
______________________________________ 
Tensile yield strength 
470 Kg/cm.sup.2 
Izod impact strength 
34 Kg cm/cm (at 20.degree. C.) 
" 28 Kg cm/cm (at 0.degree. C.) 
Rockwell hardness 
105 
Melt flow rate 2.0 g/10 min. 
______________________________________ 
EXAMPLE 8 
When 90 parts of the same latex of graft polymer as in Example 3, 100 parts 
of chloroform and 300 parts of a 0.5 wt. % dilute aqueous magnesium 
sulfate solution were continuously mixed by a continuous type kneader, the 
resulting mixture separated into an aqueous phase and a high viscous 
organic phase. This mixture was fed to the same apparatus as used in 
Example 7 and removal of the aqueous phase and devolatilization of 
chloroform were effected in the apparatus, followed by continuous feeding 
of 70 parts of said polymethyl methacrylate powder from the feed opening 
for resin to melt-mix with the graft polymer and pelletization of the 
mixture was carried out. The surface of thus obtained pellets was smooth 
and no fish eyes were seen. These were further injection molded to make 
test pieces and properties thereof were measured in the same manner as in 
Example 3 to obtain the results as shown in Table 13. These results show 
the superiority of the rubber modified thermoplastic resin produced in 
this Example. 
TABLE 13 
______________________________________ 
Items Results 
______________________________________ 
Total light transmission 
88% 
Dynstat impact strength 
19 Kg cm/cm.sup.2 
Rockwell hardness 76 
______________________________________ 
EXAMPLE 9 
140 parts of the same latex as in Example 4, 100 parts of a 1 wt. % aqueous 
sulfuric acid solution and 10 parts of toluene were continuously fed to an 
apparatus having successively a feed opening for the polymer latex, the 
aqueous sulfuric acid solution and toluene, a mixing part, a dehydrating 
part, a devolatilizing part, a feed opening for resin and a melt-mixing 
part and water separated in the apparatus was discharged from the 
dehydrating part. Volatile components mainly composed of toluene were 
devolatilized from the devolatilizing part by heating and then 50 parts of 
the same acrylonitirle-styrene copolymer as used in Example 5 was 
continuously fed from the resin feed opening provided down the 
devolatilizing part to melt-mix with the 
acrylonitrile-.alpha.-methylstyrene copolymer. 
Then, thus obtained thermoplastic resin mixture was extruded into strands 
from the apparatus and they were pelletized and dried. These pellets were 
injection molded into a transparent sheet of 3 mm thick. Vicat softening 
point (load 5 Kg) of this sheet according to ISO R-306 was measured to 
obtain 116.degree. C. Rockwell hardness HRM of the sheet was 92. These 
results show that the thermoplastic resin produced in this Example was 
excellent as a heat resistant resin. 
As is clear from the above explanation, according to the method of this 
invention, operations of coagulating polymer latex to make wet powder and 
dehydrating and drying the wet powder are not required and especially 
because heat loss at drier can be avoided, it has become possible to 
produce thermoplastic resins of high competitiveness in cost. Furthermore, 
in this invention, water is separated with an organic agent and so 
discharging of water is easy and there is no problem of clogging of the 
aperture provided at barrel part of the conventional dehydration extruder. 
Besides, since highly viscous polymer is dealt with, no consideration is 
necessary for wearing-out of apparatus. In addition, the evaporation 
latent heat of the organic agent is generally markedly smaller than water 
and reduction of quantity of heat can be accomplished. 
Thus, this invention has a high industrial value.