Continuous process for producing rubber modified high-impact resins

In a continuous bulk or solution polymerization process for producing rubber modified high-impact resins which comprises continuously feeding a raw material solution comprising a mixture of an aromatic vinyl monomer and a vinyl cyanide monomer and a rubber component dissolved in the mixture, together with a radical polymerization initiator, to a first reactor, polymerizing the raw material solution under high-shear agitation to a conversion required to transform the rubber component phase into dispersed particles, withdrawing the reaction mixture continuously from the first reactor at a rate corresponding to the feed rate of the raw material solution, and feeding the reaction mixture to a second or more reactors for further polymerization, rubber modified high-impact resins exhibiting excellent chemical resistance, thermal resistance and rigidity and having a good surface gloss can be produced by properly determining the weight ratio of the aromatic vinyl monomer to the vinyl cyanide monomer present in the raw material solution, the content of the rubber component in the raw material solution, the content of the solvent in the raw material solution, the property of the rubber component, the property of the radical polymerization initiator and the amount of initiator used, as well as the conversion of the monomers at the first reactor.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to improvements in a continuous process for 
producing rubber modified high-impact resins. More particularly, it 
relates to an improved process for producing rubber modified high-impact 
resins wherein a raw material solution comprising a mixture of an aromatic 
vinyl monomer and a vinyl cyanide monomer and a rubber component dissolved 
therein is continuously subjected to bulk or solution polymerization to 
obtain a rubber modified high-impact resin exhibiting excellent chemical 
resistance, thermal resistance and rigidity and having a good surface 
gloss. 
2. Description of the Prior Art 
High-impact polystyrenes (hereinafter referred to as "HI-PS resins") are 
resins obtained by polymerizing styrene in the presence of a rubber 
component to improve the impact resistance of the polystyrene and are 
being used in a wide range of applications. Although HI-PS resins are 
sometimes produced by batch polymerization processes (such as 
bulk--suspension polymerization processes), there is a recent tendency 
toward the increasing use of continuous bulk polymerization processes. On 
the other hand, acrylonitrile-butadiene-styrene copolymeric resins 
(hereinafter referred as "ABS resins") obtained by polymerizing styrene 
and acrylonitrile in the presence of a rubber component have found many 
uses by reason of their excellent impact resistance, chemical resistance, 
thermal resistance and rigidity as well as their good surface gloss. 
Generally, ABS resins are being produced by the so-called emulsion 
polymerization process in which styrene and acrylonitrile are added to a 
latex containing a rubber component and the resulting mixture is subjected 
to polymerization. However, a number of problems are encountered in 
carrying out this emulsion polymerization process. Specifically, 
large-scale polymerization equipment is required because the latex must be 
used in an amount equal to several times that of the desired polymer; the 
process control is complicated because a number of incidental steps such 
as emulsification, coagulation, drying and other steps are involved; and 
the resulting polymer may be unavoidably contaminated with impurities 
because such additives as emulsifiers, coagulants and the like are used. 
Accordingly, Japanese Patent Publications No. 35354/'74 and No. 35355/'74 
have proposed improved emulsion polymerization processes for producing ABS 
resins in which the rubber component present in the latex is first 
extracted with styrene and acrylonitrile and the resulting reaction 
mixture is then subjected to continuous bulk polymerization. Although 
these improved processes are simpler than the conventional emulsion 
polymerization process, they still involved a complicated extraction step. 
In addition to the above, continuous bulk or solution polymerization 
processes for producing ABS resins have also been proposed. They are 
disclosed, for example, in B.P. No. 1,121,885, D.E. No. 2,152,945, U.S. 
Pat. No. 4,198,383 and the like. It is mentioned therein that these 
processes have the advantages of simplifying the polymerization and 
after-treatment steps and decreasing the production of waste materials 
tending to induce environmental pollution. However, these processes are 
disadvantageous in that the resulting resins do not always exhibit 
excellent properties, their surface gloss especially characteristic of ABS 
resins may be impaired, and/or special equipment is needed. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a continuous 
polymerization process for producing rubber modified high-impact resins 
exhibiting excellent chemical resistance, thermal resistance and rigidity 
and having a good surface gloss. 
It is another object of the present invention to provide a process for 
producing rubber modified high-impact resins having the above-described 
excellent properties by means of equipment in common use for the 
continuous bulk or solution polymerization of HI-PS resins. 
According to the present invention, there is provided a continuous bulk or 
solution polymerization process for producing rubber modified high-impact 
resins which comprises continuously feeding a raw material solution 
comprising a mixture of an aromatic vinyl monomer and a vinyl cyanide 
monomer and a rubber component dissolved in said mixture, together with a 
radical polymerization initiator, to a first reactor, polymerizating said 
raw material solution under high-shear agitation to the conversion 
required to transform the rubber component phase into dispersed particles, 
withdrawing the reaction mixture continuously from said frst reactor at a 
rate corresponding to the feed rate of said raw material solution, and 
feeding said reaction mixture to a second or more reactors for further 
polymerization, the process being characterized in that 
(A) the weight ratio of said aromatic vinyl monomer to said vinyl cyanide 
monomer present in said raw material solution ranges from 99/1 to 50/50; 
(B) said rubber component has a viscosity of not greater than 100 
centistokes when measured as a 5% solution in styrene at 30.degree. C.; 
(C) the content of said rubber component in said raw material solution is 
not greater than 10% by weight; 
(D) the content of the solvent in said raw material solution is not greater 
than 40% by weight; 
(E) said radical polymerization initiator has a 10-hour half-life 
decomposition temperature of 100.degree. C. or below; 
(F) said radical polymerization initiator is fed to said first reactor in 
an amount of not less than 30 ppm based on said raw material solution; and 
(G) the conversion of said monomers at said first reactor is controlled in 
such a way that it lies between 10 and 35% by weight. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As the aromatic vinyl monomer used in the process of the present invention, 
there may be used one or more compounds selected from styrene, 
.alpha.-methylstyrene, styrenes having alkyl substituents on the benzene 
ring (e.g., o-, m- or p-methylstyrene and o-, m- or p-tert-butylstyrene), 
styrenes having halogen substituents on the benzene ring (e.g., o-, m- or 
p-chlorostyrene and o-, m- or p-bromostyrene), and the like. As the vinyl 
cyanide monomer, there may be used one or more compounds selected from 
acrylonitrile, methacrylonitrile and the like. If desired, copolymerizable 
monomers such as acrylic esters (e.g., methyl methacrylate), maleic 
anhydride and the like may be added to the raw material solution. 
The weight ratio of the aromatic vinyl monomer to the vinyl cyanide monomer 
present in the raw material solution can range from 99/1 to 50/50 and 
preferably from 95/5 to 50/50. If the weight ratio of the aromatic vinyl 
monomer to the vinyl cyanide monomer is greater than 99/1, the resulting 
resin will have poor chemical resistance, rigidity and thermal resistance. 
If the weight ratio is less than 50/50, the resulting resin will have a 
poor surface gloss and low fluidity. 
The rubber component can be any common rubber that is soluble in the 
above-described monomers. Specific examples of useful rubbers include 
butadiene rubber, styrene-butadiene copolymeric rubber, 
acrylonitrile-butadiene copolymeric rubber, chloroprene rubber, 
ethylene-propylene copolymeric rubber, ethylene-propylenediene copolymeric 
rubber and the like. These rubbers should have a viscosity of not greater 
than 100 centistokes when measured as a 5% solution in styrene at 
30.degree. C. It is well known that, in the case of bulk or solution 
polymerization, the rubber component which is initially present in a 
homogeneous solution separates from the other components at or above a 
certain conversion of the monomers and takes the form of dispersed 
particles. This phenomenon is generally referred to as "phase inversion". 
If the rubber component present in the raw material solution has a 
solution viscosity of greater than 100 centistokes, the resulting 
dispersed particles of the rubber component will be unduly large and, 
hence, the resulting resin will have a poor surface gloss. 
The content of the rubber component in the raw material solution should be 
not greater than 10% by weight. If the content of the rubber component in 
the raw material solution is greater than 10% by weight, the dispersed 
particles resulting from the phase inversion of the rubber component at 
the first reactor will be unduly large and, hence, the resulting resin 
will have a poor surface gloss. 
The raw material solution used in the process of the present invention may 
consist solely of the aromatic vinyl monomer, the vinyl cyanide monomer 
and the rubber component. If desired, however, a solvent selected from 
aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, 
halogenated hydrocarbons, ketones and the like can be added thereto in an 
amount of not greater than 40% by weight. If the amount of solvent used is 
greater than 40% by weight, the chain transfer effect will undesirably be 
enhanced to enlarge the resulting dispersed particles of the rubber 
component and reduce the production efficiency. 
In the first step of the process of the present invention, polymerization 
is carried out by continuously feeding the raw material solution, together 
with a radical polymerization initiator as the catalyst, to a first 
reactor. Useful radical polymerization initiators are organic peroxides, 
azo compounds and the like, and they should have a 10-hour half-life 
decomposition temperature of 100.degree. C. or below and preferably 
90.degree. C. or below. Specific examples of such radical polymerization 
initiators include lauroyl peroxide, tert-butyl peroxy(2-ethylhexanoate), 
benzoyl peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 
azobisisobutyronitrile, azobis-2-methylbutyronitrile and the like, and 
these radical polymerization initiators may be used alone or in 
combination. If the polymerization within the first reactor is thermally 
initiated without the use of any radical polymerization initiator, the 
dispersed particles resulting from the phase inversion of the rubber 
component at th first reactor will be unduly large and, hence, the 
resulting resin will have a poor surface gloss. If the polymerization is 
initiated by means of a radical polymerization initiator but its 10-hour 
half-life decomposition temperature is above 100.degree. C., it will be 
necessary to raise the polymerization temperature. Thus, the proportion of 
thermally initiated polymerization will be increased to enlarge the 
dispersed particles of the rubber component to an undue extent. 
The radical polymerization initiator should be fed to the first reactor in 
an amount of not less than 30 ppm and preferably not less than 50 ppm 
based on the raw material solution. If the amount of radical 
polymerization initiator used is less than 30 ppm, it will be necessary to 
raise the polymerization temperature. Thus, the proportion of thermally 
initiated polymerization will be increased to enlarge the dispersed 
particles resulting from the phase transition of the rubber component 
within the first reactor. 
In the process of the present invention, the conversion of the monomers at 
the first reactor should suitably be controlled in such a way that it lies 
between 10 and 35% by weight and preferably between 13 and 30% by weight. 
If the conversion of the monomers at the first reactor is less than 10% by 
weight, the degree of conversion of the monomers is so low that phase 
inversion of the rubber component cannot occur or, if it occurs, the 
resulting dispersed particles will be unstable and unduly large. If the 
conversion of the monomers at the first reactor is greater than 35% by 
weight, the dispersed particles resulting from phase inversion of the 
rubber component will be unduly large and, hence, the resulting resin will 
have a poor surface gloss. Alternatively, it may happen that the rubber 
component does not undergo phase inversion and falls into a gel state. 
No particular limitation is placed on the type of the first reactor in 
which the rubber component phase present in the raw material solution is 
subjected to phase inversion, and any reactor in common use for bulk or 
solution polymerization may be used. However, it is preferable to use a 
reactor including a screw type agitator mounted in a draft tube and 
provided with an auxiliary agitator at the bottom and having an inlet port 
for the raw material solution in its bottom. In this case, the 
relationship between the agitation speed N (in rps) of the screw type 
agitator and the diameter D (in meters) of the screw type agitator is 
preferably represented by 
EQU N.sup.2 .multidot.D&gt;1.0. 
It is generally known that, in the phase inversion stage for transforming 
the rubber component into dispersed particles within a reactor, the size 
of the resulting dispersed particles depends on the agitation intensity of 
the reactor. 
If N.sup.2 .multidot.D.ltoreq.1.0, the agitation intensity is so low that 
the resulting dispersed particles of the rubber component will be unduly 
large and, hence, the surface gloss of the resulting resin will be 
impaired. 
The above-described first reactor for subjecting the rubber component 
present in the raw material solution to phase inversion may also comprise 
a reactor including a helical-ribbon-blade provided with an auxiliary 
agitator at the bottom and having an inlet port for the raw material 
solution in its bottom. In this case, the relationship between the 
agitation speed N (in rps) of the helical-ribbon-blade and the diameter D 
(in meters) of the helical-ribbon-blade is preferably represented by 
EQU N.sup.2 .multidot.D&gt;1.0. 
If N.sup.2 .multidot.D.ltoreq.1.0, the agitation intensity is so low that 
the resulting dispersed particles of the rubber component will be unduly 
large and, hence, the surface gloss of the resulting resin will be poor. 
Thus, the raw material solution comprising a mixture of the aromatic vinyl 
monomer and the vinyl cyanide monomer and the rubber component dissolved 
therein, together with the radical polymerization initiator, is 
continuously fed to the first reactor and polymerized under high-shear 
agitation so as to transform the rubber component into finely dispersed 
particles. The reaction mixture is then, continuously withdrawn from the 
first reactor at the rate corresponding to the feed rate of the raw 
material solution, and fed to a second or more reactors for further 
polymerization. No particular limitation is placed on the type of the 
second or more reactors in which the reaction mixture withdrawn 
continuously from the first reactor is subjected to further 
polymerization, and any reactor in common use for bulk or solution 
polymerization may be used. Preferably, one to five reactors, one to five 
tubular or tower reactors of the piston flow type, or a combination 
thereof is used for this purpose. It is a common practice to continue the 
polymerization of the monomers in these second or more reactors until the 
desired conversion is attached and then withdraw the reaction mixture 
continuously from the final reactor. The reaction mixture withdrawn from 
the final reactor is introduced into a conventionally known 
devolatilization device for removing unreacted monomers and the solvent. 
Thereafter, the polymer is recovered as a resin product. 
In the process of the present invention, a chain transfer agent such as a 
mercaptan may be used, if desired, in order to regulate the molecular 
weight of the resulting polymer. Where such a chain transfer agent is 
used, it may be totally added to the raw material solution. However, it is 
preferable to add a part of the chain transfer agent to the reaction 
mixture withdrawn from the first reactor. Moreover, if desired, an 
antioxidant such as an alkylated phenol and a plasticizer or lubricant 
such as butyl stearate, zinc stearate, mineral oil or the like may also be 
added either to the raw material solution or to the reaction mixture 
during the course of the polymerization or upon completion of the 
polymerization. 
According to the process of the present invention, an aromatic vinyl 
monomer and a vinyl cyanide monomer can be subjected to continuous bulk or 
solution polymerization in the presence of a rubber component by using 
equipment in common use for the continuous bulk or solution polymerization 
of HI-PS resins and following substantially the same procedure as for the 
continuous bulk or solution polymerization of HI-PS resins. Thus, ABS 
resins exhibiting excellent chemical resistance, thermal resistance and 
rigidity and having a good surface gloss can be produced. 
The present invention is further illustrated by the following examples in 
which parts are by weight:

EXAMPLE 1 
A raw material solution was prepared by using 6.0 parts of a polybutadiene, 
commercially available under the trade name of "Asaprene 700A" from Asahi 
Kasei Co., as the rubber component and dissolving it in a mixture (in a 
styrene/acrylonitrile weight ratio of 75/25) of 55.5 parts of styrene, 
18.5 parts of acrylonitrile, and 20.0 parts of ethylbenzene. Asaprene 700A 
has a viscosity of 45 centistokes when measured as a 5% solution in 
styrene at 30.degree. C. After the addition of 0.1 part of tert-dodecyl 
mercaptan, 0.02 part of benzoyl peroxide (BPO: 10-hour half-life 
decomposition temperature, 74.degree. C.) as a radical polymerization 
initiator, and 0.20 part of 2,6-di-tert-butylphenol as an antioxidant, the 
raw material solution was continuously fed at a rate of 15.0 liters per 
hour to a first reactor including a screw type agitator mounted in a draft 
tube and provided with an auxiliary agitator at the bottom and having an 
inlet port for the raw material solution in its bottom. The internal 
volume of the first reactor was 18.0 liters and the outer diameter of the 
screw type agitator was 0.18 meter. In the first reactor, polymerization 
was carried out at a temperature of 110.degree. C. with the agitator 
operated at a agitation speed of 3 rps, so that the rubber component was 
subjected to phase inversion (i.e., transformed into finely dispersed 
particles). The reaction mixture, having undergone polymerization in the 
first reactor, was continuously withdrawn therefrom and fed to a second 
reactor for further polymerization. The conversion of the monomers at the 
first reactor was 25% by weight. As the second reactor, there was used a 
perfect-mixing type reactor including a screw type agitator mounted in a 
draft tube and not provided with any auxiliary agitator. The reaction 
mixture, having undergone polymerization in the second reactor, was 
continuously withdrawn therefrom and successively fed to third, fourth and 
fifth reactors. Thus, the polymerization was continued in such a way that 
the conversion of the monomers at the fifth reactor was 73% by weight. The 
third, fourth and fifth reactors were of the same type as the second one. 
The reaction mixture withdrawn continuously from the fifth reactor was 
introduced into a conventionally known devolatilization device to remove 
unreacted monomers and the solvent at an elevated temperature and a high 
vacuum, and then pelletized with an extruder to obtain an ABS resin 
product. Using a 4-ounce injection molding machine, test pieces were made 
of the product and their properties were evaluated. The evaluation results 
are shown in Table 1. (The evaluation results obtained in the succeeding 
examples are also summarized in Table 1.) 
As can be seen from these evaluation results, the product exhibited 
excellent fluidity, impact resistance, rigidity and thermal resistance and 
had a good surface gloss. 
In the succeeding examples, the after-treatment and molding conditions were 
all the same as in this example. 
EXAMPLE 2 
The procedure of Example 1 was repeated except that the polybutadiene used 
as the rubber component in the raw material solution was replaced by a 
styrene-butadiene copolymer, commercially available under the trade name 
of "TUFDENE 2000A" from Asahi Kasei Co. and having a viscosity of 50 
centistokes when measured as a 5% solution in styrene at 30.degree. C. 
EXAMPLE 3 
The procedure of Example 1 was repeated except that the 
styrene/acrylonitrile weight ratio of the raw material solution was 
changed to 59/41 (i.e., 43.66 parts of styrene and 30.34 parts of 
acrylonitrile) and the polymerization temperature of the first reactor was 
reduced to 108.degree. C. Moreover, styrene was continuously added to the 
reaction mixture at the respective inlet ports of the second to fifth 
reactors so that the weight ratio of unreacted styrene to unreacted 
acrylonitrile might be adjusted to 59/41. 
EXAMPLE 4 
The procedure of Example 1 was repeated except that a raw material solution 
consisting of 8.0 parts of the rubber component, 54.0 parts of styrene, 
18.0 parts of acrylonitrile and 20.0 parts of ethylbenzene was used, the 
polymerization temperature of the first reactor was reduced to 109.degree. 
C., and the agitation speed of the agitator was raised to 4 rps. The 
conversion of the monomers at the first reactor was 23% by weight. 
EXAMPLE 5 
The procedure of Example 1 was repeated except that 0.04 part of lauroyl 
peroxide (LPO: 10-hour half-life decomposition temperature, 62.degree. C.) 
was used as the radical polymerization initiator and the polymerization 
temperature of the first reactor was reduced to 105.degree. C. The 
conversion of the monomers at the first reactor was 24% by weight. 
EXAMPLE 6 
The procedure of Example 1 was repeated except that the first reactor was 
replaced by a reactor including a helical-ribbon-blade provided with an 
auxiliary agitator at the bottom and having an inlet port for the raw 
material solution in its bottom, the raw material solution was fed at a 
rate of 16.2 liters per hour, and the agitation speed of the agitator was 
reduced to 2.5 rps. The internal volume of the first reactor was 18.8 
liters and the outer diameter of the helical-ribbon-blade was 0.25 meter. 
EXAMPLE 7 
The procedure of Example 1 was repeated except that the second to fifth 
reactors were replaced by four commonly-used tower reactors of the piston 
flow type. 
EXAMPLE 8 
The procedure of Example 1 was repeated except that a raw material solution 
was prepared by dissolving 5.0 parts of the polybutadiene, "Asaprene 
700A", in a mixture of 45.0 parts of styrene, 15.0 parts of acrylonitrile 
and 35.0 parts of ethylbenzene and then 0.03 part of BPO and 0.2 part of 
2,6-di-tert-butylphenol were added. The conversion of the monomers at the 
first reactor was 25% by weight. 
EXAMPLE 9 
The procedure of Example 1 was repeated except that a raw material solution 
was prepared by dissolving 6.0 parts of the polybutadiene, "Asaprene 
700A", in a mixture of 66.7 parts of styrene, 22.3 parts of acrylonitrile 
and 5.0 parts of ethylbenzene, then 0.01 part of BPO, 0.2 part of 
tert-dodecyl mercaptan and 0.2 part of 2,6-di-tert-butylphenol were added 
to the raw material solution, and an ethylbenzene/styrene/acrylonitrile 
mixture in a weight ratio of 50.0/37.5/12.5 was continuously fed to the 
inlet port of the second reactor at a rate of 4 liters per hour. The 
conversion of the monomers at the first reactor was 16% by weight. 
COMATIVE EXAMPLE 1 
The apparatus used in this comparative example was the same as used in 
Example 1. A raw material solution was prepared dissolving 6.0 parts of 
the polybutadiene, "Asaprene 700A", in a mixture of 74.0 parts of styrene 
and 20.0 parts of ethylbenzene. After the addition of 0.03 part of BPO as 
a polymerization initiator and 0.20 part of 2,6-di-tert-butylphenol as an 
antioxidant, the raw material solution was continuously fed to the first 
reactor at a rate of 12.0 liters per hour and polymerized at 115.degree. 
C. The conversion of the monomer at the first reactor was 22% by weight. 
The polymerization within the second and succeeding reactors was carried 
out in such a way that the conversion of the monomer at the fifth reactor 
was 73% by weight. In other respects, the procedure of Example 1 was 
repeated. The resulting product was inferior in impact resistance, 
rigidity and thermal resistance to the ABS resin obtained in Example 1. 
The evaluation results are shown in Table 2. (The evaluation results 
obtained in the succeeding comparative examples are also summarized in 
Table 2. The after-treatment and molding conditions were all the same as 
in Example 1.) 
COMATIVE EXAMPLE 2 
The procedure of Example 3 was repeated except that the 
styrene/acrylonitrile weight ratio of the raw material solution was 
changed to 40/60 (i.e., 29.6 parts of styrene and 44.4 parts of 
acrylonitrile) and 0.20 part of tert-dodecyl mercaptan was added to the 
raw material solution. The resulting product exhibited an increase in 
thermal resistance and rigidity, but a decrease in fluidity, impact 
strength and gloss. 
COMATIVE EXAMPLE 3 
The procedure of Example 1 was repeated except that another polybutadiene, 
commercially available under the trade name of "Diene NF55A" from Asahi 
Kasei Co. and having a viscosity of 160 centistokes when measured as a 5% 
solution in styrene at 30.degree. C., was used as the rubber component in 
the raw material solution. The dispersed particles of the rubber component 
were so large that the resulting product had a poor gloss. 
COMATIVE EXAMPLE 4 
The procedure of Example 1 was repeated except that a raw material solution 
consisting of 12.0 parts of the rubber component, 51.0 parts of styrene, 
17.0 parts of acrylonitrile and 20.0 parts of ethylbenzene was used. As a 
result, the reaction mixture increased in viscosity and formed a gel prior 
to phase inversion within the first reactor, so that no normal product 
could be obtained. 
COMATIVE EXAMPLE 5 
The procedure of Example 1 was repeated except that the polymerization 
initiator was replaced by 0.04 part of di-tert-butyl peroxide (DTBPO: 
10-hour half-life decomposition temperature, 124.degree. C.). The 
resulting product had a poor gloss. 
COMATIVE EXAMPLE 6 
The procedure of Example 1 was repeated except that no polymerization 
initiator was used and the polymerization was thermally initiated by 
raising the temperature of the first reactor to 130.degree. C. The 
resulting product had a poor gloss. 
COMATIVE EXAMPLE 7 
The procedure of Example 1 was repeated except that the polymerization 
temperature of the first reactor was reduced to 90.degree. C. The 
conversion of the monomers at the first reactor was 9% by weight and the 
reaction mixture residing in the first reactor did not undergo any phase 
invention. 
COMATIVE EXAMPLE 8 
The procedure of Example 1 was repeated except that the polymerization 
temperature was raised to 117.degree. C. The conversion of the monomers at 
the first reactor was 40% by weight. The resulting product had a poor 
gloss. 
COMATIVE EXAMPLE 9 
A raw material solution was prepared by dissolving 5.0 parts of the 
polybutadiene, "Asaprene 700A", in a mixture of 37.5 parts of styrene, 
12.5 parts of acrylonitrile and 45.0 parts of ethylbenzene. After the 
addition of 0.05 part of BPO and 0.2 part of 2,6-di-tert-butylphenol, the 
raw material solution was continuously fed to the first reactor. 
Thereafter, the procedure of Example 1 was repeated. Although the 
conversion of the monomers at the first reactor was 30% by weight, the 
dispersed particles of the rubber component were so large that the 
resulting product had a poor gloss. Moreover, its yield was decreased. 
REFERENCE EXAMPLE 
The procedure of Example 1 was repeated except that the agitation speed of 
the screw type agitator included in the first reactor was reduced to 2 
rps. The resulting product had a poor gloss. 
TABLE 1 
__________________________________________________________________________ 
Example No. 1 2 3 4 5 6 7 8 9 
__________________________________________________________________________ 
Raw material solution 
Rubber component (parts) 
6.0 6.0 6.0 8.0 6.0 6.0 6.0 5.0 6.0 
Type of rubber component 
Asaprene 
TUFDENE 
Asaprene 
Asaprene 
Asaprene 
Asaprene 
Asaprene 
Asaprene 
Asaprene 
700A 2000A 700A 700A 700A 700A 700A 700A 700A 
Styrene/acrylonitrile 
75/25 
75/25 59/41 
75/25 
75/25 
75/25 
75/25 
75/25 
75/25 
weight ratio 
Ethylbenzene (parts) 
20.0 20.0 20.0 20.0 20.0 20.0 20.0 35.0 5.0 
Initiator (parts) 
0.02 0.02 0.02 0.02 0.04 0.02 0.02 0.03 0.01 
Type of initiator 
BPO BPO BPO BPO LPO BPO BPO BPO BPO 
Conversion of monomers at first 
25 25 25 23 24 25 25 25 16 
reactor (% by weight) 
Agitation speed of agitator of 
3 3 3 4 3 2.5 3 3 3 
first reactor (rps) 
N.sup.2 .multidot. D 
1.62 1.62 1.62 2.88 1.62 1.56 1.62 1.62 1.62 
Properties 
Melt flow index.sup.1 
2.0 2.0 1.6 1.8 2.0 2.0 1.9 1.9 2.1 
(g/10 min) 
Yield strength in 
540 560 590 450 540 540 540 530 580 
tension.sup.2 (kg/cm.sup.2) 
Izod impact strength.sup.3 
11.1 11.5 10.6 14.8 11.2 11.2 11.5 12.1 9.8 
(kg-cm/cm) 
Gloss.sup.4 (%) 70 71 71 66 70 70 70 65 71 
Vicat softening point.sup.5 
108.2 
108.4 110.1 
107.6 
108.0 
108.3 
108.0 
108.6 
108.0 
(.degree.C.) 
Styrene/acrylonitrile weight 
75/25 
75/25 70/30 
75/25 
75/25 
75/25 
75/25 
75/25 
75/25 
ratio in polymer 
__________________________________________________________________________ 
(Notes) 
Molding conditions: 4ounce injection molding machine; molding temperature 
230.degree. C.; mold temperature, 50.degree. C. 
.sup.1 ASTM D1238 (200.degree. C.; 5,000 g). 
.sup.2 ASTM D638. 
.sup.3 ASTM D256 (1/4 inch .times. 1/2 inch notched specimen). 
.sup.4 JISZ-8741 (angle of incidence, 60.degree.). 
.sup.5 ASTM D1525 (load, 1 kg). 
TABLE 2 
__________________________________________________________________________ 
Refer- 
ence 
Ex- 
Comparative Example No. 
1 2 3 4 5 6 7 8 9 ample 
__________________________________________________________________________ 
Raw material solution 
Rubber component (parts) 
6.0 6.0 6.0 12.0 6.0 6.0 6.0 6.0 5.0 6.0 
Type of rubber component 
Asaprene 
Asaprene 
Diene 
Asaprene 
Asaprene 
Asaprene 
Asaprene 
Asaprene 
Asaprene 
Asa- 
700A 700A NF55A 
700A 700A 700A 700A 700A 700A prene 
700A 
Styrene/acrylonitrile 
100/0 
40/60 
75/25 
75/25 
75/25 
75/25 
75/25 
75/25 
75/25 
75/25 
weight ratio 
Ethylbenzene (parts) 
20.0 20.0 20.0 
20.0 20.0 20.0 20.0 20.0 45.0 20.0 
Initiator (parts) 
0.03 0.02 0.02 
0.02 0.04 0 0.02 0.02 0.05 0.02 
Type of initiator 
BPO BPO BPO BPO DTBPO 
-- BPO BPO BPO BPO 
Conversion of monomers at 
22 24 25 -- 23 23 9 40 30 25 
first reactor (% by weight) 
Agitation speed of agitator of 
3 3 3 3 3 3 3 3 3 2 
first reactor (rps) 
N.sup.2 .multidot. D 
1.62 1.62 1.62 
1.62 1.62 1.62 1.62 1.62 1.62 0.72 
Properties 
Melt flow index 
2.8 0.8 2.0 -- 2.1 2.0 -- 2.0 1.7 2.0 
(g/10 min) 
Yield strength in 
300 650 500 -- 510 500 -- 520 510 530 
tension (kg/cm.sup.2) 
Izod impact strength 
7.3 7.5 8.3 -- 8.5 8.3 -- 8.6 13.1 10.0 
(kg-cm/cm) 
Gloss (%) 65 62 18 -- 30 24 -- 33 38 48 
Vicat softening point 
102.4 
112.1 
108.1 
-- 107.9 
108.1 
-- 108.3 
107.7 
108.3 
(.degree.C.) 
Styrene/acrylonitrile weight 
100/0 
65/35 
75/25 
-- 75/25 
75/25 
-- 75/25 
75/25 
75/25 
ratio in polymer 
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