Modified thermoplastic resins

The present invention relates to high impact strength polymeric compositions comprising acrylonitrile-butadiene-styrene terpolymers, carbon black and a nitrile rubber additive. The presence of the rubber additive restores the impact strength of the acrylonitrile-butadiene-styrene compositions, which is normally substantially degraded by the addition of carbon black.

BACKGROUND OF THE INVENTION 
The invention relates to new and improved high impact strength resin 
compositions having physical properties which make the same valuable for 
applications where toughness and high impact strength are required, such 
as in plastic pipe. 
ABS, i.e., acrylonitrile-butadiene-styrene terpolymer and similar related 
compositions are well known in the art. Where these and related 
compositions are used for certain applications, such as making plastic 
pipe or other articles which might be exposed to ultraviolet light 
sources, carbon black is usually incorporated therein in small amounts as 
a pigment for screening out ultraviolet light. However, the addition of 
required amounts of carbon black for this purpose usually has been found 
to cause severe degradation of the impact strength thereof. This is 
especially disadvantageous where it is desired to use ABS compositions for 
uses where carbon black is required, for example, to make drain, waste and 
vent (DWV) pipe which has certain impact strength standards for ambient 
(e.g., about 23.degree. C.) temperatures, or where high impact strength at 
sub-zero (e.g., about -40.degree. C.) temperatures is also desired. See 
ASTM D-2661 (1974). Accordingly, it is an object of this invention to 
provide ABS termpolymer/carbon black polymeric compositions which have 
high impact strength and good toughness, as determined by standard Notched 
Izod and Gardner drop weight tests at ambient and sub-zero temperatures. 
SUMMARY OF THE INVENTION 
It has been surprisingly discovered the impact strength and other desirable 
properties of ABS and ABS-type polymeric resins can be retained despite 
the addition of carbon black (said compositions being sometimes referred 
to herein as ABS or ABS-type/CB resins) thereto, by incorporating therein 
certain nitrile rubber copolymers. These nitrile rubber copolymers can 
advantageously be added during the preparation of the ABS resin mixture, 
or can be melt-blended with the ABS terpolymer before or after the carbon 
black (CB) addition, or can be premixed with the carbon black to form a 
concentrate for melt-blending with the ABS or ABS-type resin. The 
resulting modified polymeric compositions retain or exceed the desired 
high ambient impact strength of the ABS or ABS-type resin used and 
additionally have good low temperature impact resistance and increased 
overall toughness, such as determined by Gardner drop weight tests. The 
compositions of the present invention are thus highly useful for 
applications such as making plastic pipe containing CB. 
DETAILED DESCRIPTION OF THE INVENTION 
The invention, in its broadest form, concerns a polymeric composition 
comprising (a) an ABS or ABS-type terpolymer comprising an alkenyl 
aromatic monomer, a vinyl cyanide monomer and a rubber monomer or 
rubber-containing copolymer, (b) carbon black, and (c) a sufficient amount 
of a butadiene-acrylonitrile copolymer rubber to substantially minimize 
the detrimental effect of carbon black on the impact strength of (a). In a 
highly preferred embodiment, the invention concerns polymeric compositions 
which comprise (a) an acrylonitrile-butadiene-styrene terpolymer, e.g., 
ABS resin, (b) carbon black, and (c) a butadiene-acrylonitrile copolymer 
rubber in a sufficient amount to substantially minimize the detrimental 
effect of carbon black on the impact strength of (a). The term 
"substantially minimize" means that the impact strength (hereinafter to be 
construed as determined by the standard Notched Izod or drop-weight type 
Impact Strength (ft-lb/inch) at 73.degree. C. of the polymeric composition 
is about equal to or greater than the impact strength of the terpolymer 
composition (a) alone. Sufficient amounts of the copolymer rubber are 
preferably used to provide a polymeric composition having an impact 
strength (at 73.degree. F.) greater than the impact strength of the 
terpolymer component (a) alone under the same test conditions. Preferably, 
amounts of the copolymer rubber sufficient to provide from about 0.2 to 
about 20.0 weight % thereof of total polymeric composition are employed. 
In another preferred embodiment, the amount of copolymer rubber employed 
is sufficient to provide a polymeric composition characterized by high 
impact strengths at ambient and sub-zero temperatures. In a further 
embodiment, a polymeric composition having sufficient amounts of copolymer 
rubber to provide impact strengths about the same as or greater than the 
impact strengths of component (a) at 73.degree. F. and -40.degree. F. 
temperatures is preferred. In still another embodiment, the polymeric 
compositions of the present invention are preferably melt blends of a 
component (a) terpolymer with the carbon black and nitrile rubber 
components (b) and (c), components (b) and (c) further being preferably 
employed together in a concentrate form. 
By the term "alkenyl aromatic monomer" is meant an alkenyl aromatic 
compound having the general formula 
##STR1## 
wherein Ar represents an aromatic hydrocarbon radical, or an aromatic 
halohydrocarbon radical of the benzene series, and R is hydrogen or the 
methyl radical. Examples of such alkenyl aromatic monomers are styrene, 
.alpha.-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 
ar-ethylstyrene, ar-vinylxylene, ar-chlorostyrene or ar-bromostyrene and 
the like. Beneficially, such monomers are employed in an amount up to 
about 75 weight percent of the total terpolymer composition (a), and 
advantageously from about 50 to 60 weight percent of the terpolymer 
composition. 
Suitable vinyl cyanide monomers include methacrylonitrile, acrylonitrile 
and the like, which are usually employed in amounts of from about 15 to 
about 30 wt. % of the total terpolymer composition (a). 
The rubber can be one or more conjugated diene, e.g., 1,3-butadiene, 
isoprene, piperylene, chloroprene, etc., including homopolymers and 
interpolymers thereof. The rubber can also comprise up to an equal amount 
by weight of one or more copolymerizable monoethylenically unsaturated 
monomers, such as monovinylidene aromatic hydrocarbons (e.g., styrene; an 
aralkylstyrene, such as the o-, m- and p-methylstyrenes, 
2,4-dimethylstyrene, the ar-ethylstyrenes, p-tert-butyl-styrene, etc.; an 
.alpha.-alkylstyrene, such as .alpha.-methylstyrene, .alpha.-ethylstyrene, 
.alpha.-methyl-p-methylstyrene, etc.; vinyl naphthalene, etc.) ar-halo 
monovinylidene aromatic hydrocarbons (e.g., the o-, m- and 
p-chlorostyrenes, 2,4-dibromostyrene, 2-methyl-4-chlorostyrene, etc.); 
acrylonitrile; methacrylonitrile; alkyl acrylates (e.g., methyl acrylate, 
butyl acrylate, 2-ethylhexyl acrylate, etc.), the corresponding alkyl 
methacrylates; acrylamides (e.g., acrylamide, methacrylamide, N-butyl 
acrylamide, etc.); unsaturated ketones (e.g., vinyl methyl ketone, methyl 
isopropenyl ketone, etc.); .alpha.-olefins (e.g., ethylene, propylene, 
etc.); pyridines; vinyl esters (e.g., vinyl acetate, vinyl stearate, 
etc.); vinyl and vinylidene halides (e.g., the vinyl and vinylidene 
chlorides and bromides, etc.); and the like. 
Numerous ABS resins which can be used as component (a) herein are made by a 
variety of processes and are commercially available. These generally 
comprise from about 6 to about 30 wt. % total rubber; from about 15 to 
about 30 wt. % acrylonitrile, from about 0.5 to about 1.5 wt. % additives, 
(e.g., anti-oxidants, stabilizers, and the like), the balance being 
styrene. As hereinafter referred to, the phrase "the balance being 
essentially styrene" is understood to be inclusive of the amounts of 
typically employed additives. Preferably, component (a) comprises from 
about 6 to about 20 wt. % total rubber, from about 17 to about 25 wt. % 
acrylonitrile, the balance being essentially styrene and small amounts of 
additives. A preferred component (a) comprises approximately about 12 to 
about 20 wt. % total rubber, about 20-25 wt. % acrylonitrile, the balance 
being styrene and small amounts of typical additives. 
The rubber copolymer component (c) likewise may be any conventional rubbery 
copolymer containing, for example, from about 20 to about 50 or more % by 
weight acrylonitrile and correspondingly from about 80 to about 50 or less 
wt. % of butadiene, with small amounts of typical additives, which is 
effective to at least substantially minimize the detrimental effect of 
carbon black on the impact strength of component (a). Representative 
examples of such rubbery copolymers include those known in the trade, such 
as the Hycar series, e.g., -1432, 1034-60, etc., as described in a 1976 
Bulletin E-2, Manual HM-1 (revised) by the B. F. Goodrich Chemical Co., 
Chemigum nitrile rubbers, e.g., -N318B, N715B, etc., as described in 
"Technical Book Facts (CG-39) on Chemigum", 1974, by the Goodyear Tire and 
Rubber Co., Paracril (UniRoyal Chemical Co.), FR-N (Firestone Synthetic 
Rubber and Latex Co.) Krynac (Polysar, Inc.) and the like. 
Illustratively, Hycar 1053 is a non-crosslinked, low temperature 
polymerized random copolymer of about 29 wt. % acrylonitrile and about 71 
wt. % butadiene. Nitrile rubbers having a nominal acrylonitrile (AN) of 
from about 25 to about 35 wt. % are preferred. Further preferred are the 
preceding compositions having an average Mooney viscosity (ML-4 @ 
100.degree. C.) of from about 30 to about 65. The rubbery copolymer may be 
premixed with the carbon black such as, for example, Regal 300, Regal 
SRF-S, Raven 1000, and the like by solution or, preferably, melt blending. 
The carbon black is usually employed in amounts of from about 0.2 to about 
0.5 wt. % or more of the polymeric composition, depending upon the desired 
end use, with amounts of about 0.35 wt. % typically being used for DWV 
pipe applications. 
Preferably, a premix concentrate (hereinafter NRBC concentrate) comprising 
the rubbery copolymer (about 20 to about 80, preferably about 20 to about 
40% by weight), carbon black (about 2 to about 50% by weight), the balance 
being ABS or an ABS-type terpolymer (usually from about 10 to about 75 
weight %) is employed to form the finished polymeric compositions 
disclosed herein and constitutes a preferred embodiment of the invention. 
In a particular preferred embodiment, the NRBC concentrate comprises from 
about 30 to about 40 weight % rubbery copolymer, the remainder being 
carbon black and an ABS or ABS-type resin, e.g., a terpolymer comprising 
an alkenyl aromatic monomer, a vinyl cyanide monomer and a rubber monomer 
or rubber-containing copolymer. In another preferred embodiment, the NRBC 
concentrate comprises from about 30 to about 35 weight % carbon black, 
from about 30 to about 35 weight % rubbery copolymer and about 30 to about 
35 weight % ABS or ABS-type resin. Preferably, ABS is used in foregoing 
embodiments. A plasticizer, such as dioctyl-adipate, dioctyl-phthalate or 
the like can be employed, if desired, in amounts ranging from about 1 to 
about 6% by weight of the concentrate. In a highly preferred embodiment, 
the concentrate comprises about 35 weight % carbon black and about 32.5 
weight % each of ABS and rubbery copolymer. While a concentrate of NR and 
CB alone can be prepared, the same is usually either undesirably tacky 
and/or tends to cross-link to a detrimental degree. Accordingly, use of 
ABS or an ABS-type terpolymer, preferably ABS, and amounts of rubbery 
copolymer ranging from about 20 to about 40 weight %, are preferred for 
avoiding the noted disadvantages and for preparing NRBC concentrates of 
the present invention; such concentrates can be used to provide ABS or 
ABS-type resins having impact strengths higher than would be expected when 
CB is incorporated therein. The ABS resin used in the concentrate 
preferably comprises from about 15 to about 23 weight % acrylonitrile, 
from about 6 to about 16 weight % total rubber, the balance being mostly 
stryrene (including typical additives). The rubber copolymer preferably 
comprises about 25-35 weight % acrylonitrile and about 65-75 wt. % 
butadiene. The concentrate compositions can be prepared by melt blending 
(by internal mixer, extruder, roll mill, etc.) although solution blending 
can be employed. In a melt blend process, the ingredients are mixed at an 
appropriate temperature, usually about 200.degree. C. for a period of 
about 2 to about 3 minutes using an internal mixer, such as a Banbury 
mixer. Where solution blending is desired, the carbon black can be mixed 
using an ultrasonic bath, with a dispersant medium such as acetone, or the 
like and the rubber copolymer then mixed therewith. The resulting mixture 
can be poured onto a tray and the dispersant medium evaporated therefrom, 
with the residue obtained being dried in an oven. 
The polymeric compositions of the present invention can be prepared by 
melt-blending the NRBC concentrate, or a carbon black concentrate and 
rubbery copolymer (c), each as separate ingredients, with the desired 
component (a) terpolymer, or by adding the nitrile rubber during mass 
polymerization preparation of the component (a) terpolymer, and melt 
blending the resulting composition with the carbon black. Sufficient 
amounts of the concentrate or of the separate ingredients thereof are used 
to provide a desired concentration of the carbon black and rubber 
copolymer in the finished polymeric composition. While ranges for the 
rubber copolymer and carbon black have been previously noted, those 
skilled in the art will recognize the amount of each to be employed will 
vary depending upon the particular end use desired, the NR or CB being 
employed, etc. The amount needed for any particular application can, 
however, be readily determined by simple experimental evaluation according 
to the teachings of the specification and the examples given herein. In a 
preferred embodiment, about one part by weight of an NRBC concentrate 
comprising about 30-35% each of carbon black, nitrile rubber copolymer and 
ABS resin is melt-blended with about 99 parts by weight of the component 
(a) terpolymer to form a preferred polymeric composition. 
In what is believed to be the best mode presently known for preparing the 
polymeric products of the present invention, an NRBC premix concentrate is 
melt-blended with the component (a) terpolymer by extruding (2 passes) the 
premix and component (a) at about 193.degree. C. using a screw speed 
setting of about 40 or more rpm for a two-stage 3/4" single screw Killion 
extruder (L/D=20/1) or corresponding screw speed for other extruders 
employed. It has also been found that components (a) and (c) can be 
melt-blended in a twin-screw extruder (0.8" Welding Engineer's) using a 
single extrusion pass, optimum results being obtained using a high shear 
screw arrangement, high screw speed, and lowest possible barrel 
temperature. 
Where it is desired to incorporate the nitrile rubber component (c) 
directly into component (a) during preparation of (a), the same can be 
done provided the process for preparing component (a) is a mass 
polymerization process. The resulting product can then be melt blended 
with the carbon black. However, it is to be understood that, where 
component (a) is to be melt-blended with components (b) and (c) separately 
or with (b) and (c) as a premix, the component (a) source is not limited 
by any particular method used to prepare the same. Thus, where it is 
desired to add the nitrile rubber during the mass polymerization 
preparation of ABS component (a), it is believed the best mode presently 
known for accomplishing the same comprises introducing the nitrile rubber 
component with a second feed stream of diluent and additional monomers to 
the second stage of a typical 3-stage mass polymerization reactor system. 
This particular method appears desirable as phase inversion of the base 
rubber monomer does not appear to be delayed, and may be accelerated by 
the addition of the nitrile rubber, which is incompatible with the base 
rubber of the ABS resin. While it is not desired to limit this aspect of 
the invention to any particular theory of operation, it appears that the 
rubbery copolymer (b) causes a reduction in the final rubber particle size 
of the finished resin, and also enters into some type of bond with the 
carbon black particles. Such bonding may result in an overall stronger 
association of the carbon black with the styrene-acrylonitrile matrix 
phase of the component (a) resin.

EXAMPLE 1 
Carbon black and carbon black-nitrile rubber concentrates can typically be 
prepared by solution blending or by melt-blending procedures. In an 
illustrative melt-blending procedure, the carbon black, nitrile rubber 
(e.g., Hycar 1053) and an ABS resin, are melt-blended at about 
201.degree.-204.degree. C. for about 1-3 minutes in a conventional Banbury 
mixer. 200 ppm of polyglycol E400 were added to each concentrate before 
packaging. In other procedures where only a CB concentrate (no NR) is 
desired, the same can be prepared by milling the carbon black with an 
ABS-type resin (using a two-roll mill) to first obtain an even dispersion 
of the carbon black, then melt-blending the composition in a Banbury 
mixer. The various carbon black (SBC or EBC) or nitrile rubber-carbon 
black (NRBC) concentrates prepared by the above or other known procedures 
were as follows (all % are by weight): 
______________________________________ 
% Carbon % Nitrile % ABS.sup.(a) 
Reference Code 
Black Rubber Resin 
______________________________________ 
1. SBC #1.sup.(b) 
35.0 0 59.0 
2. SBC #2 " " " 
3. EBC #1 " " " 
4. EBC #2 " " " 
5. NRBC #1 5.0 72.0.sup.(c) 
23.0 
6. NRBC #2 7.0 70.0 " 
7. NRBC #3 35.0 32.5 32.5 
______________________________________ 
.sup.(a) ABS resin = nominally 17% acrylonitrile, 7% butadiene, balance 
styrene. 
.sup.(b) Samples 1-4 all contain about 6% dioctylphthalate plasticizer; 
Regal 300 Carbon Black used in Samples 1-2, Regal SRFS Carbon Black used 
in Samples 3-8. 
.sup.(c) The nitrile rubber in Samples 5-7 was 29% acrylonitrile, 71% 
butadiene (Hycar 1053); Hycar 1453 (crumb form of 1053) used in Sample No 
7. 
EXAMPLE 2 
The concentrates of Example 1 above were then melt-blended by extrusion 
with ABS thermoplastic resins as component (a) of the compositions of the 
invention, sufficient amounts of the concentrates being employed to 
provide 0.35 wt. % of carbon black in the final thermoplastic composition 
(0.35 wt. % carbon black being the amount typically used to protect DWV 
pipe against UV degradation). Thus, for example, 1 part of NRBC #3 per 99 
parts of ABS is utilized to provide 0.35 wt. % in the melt-blended 
composition. Specimens of the prepared compositions were then molded for 
impact testing. 
MELT BLENDING 
A small two-stage 3/4" single screw Killion extruder (L/D=20/1) was used 
for all extrusions. The extruder was equipped with a cooling water through 
and a pellet cutter. The materials were hand-mixed and dried at around 
60.degree. C. in a vacuum oven before and after each extrusion. The 
extrusion conditions were as follows: 
Barrel temperature: 380.degree. F. (193.degree. C.) (all three zones) 
Nozzle temperature: 380.degree. F. (193.degree. C.) 
Screw speed: 54 rpm 
Number of extrusion passes: 2. 
SPECIMEN PREATION 
All impact specimens were compression molded unless mentioned otherwise. 
The molding procedure is as follows: 
(1) Preheat mold with sample in hot press for 10 minutes at 410.degree. F. 
(210.degree. C.). 
(2) Pressure up gradually to 20 tons in 11/4 minutes. 
(3) Hold at 20 tons and 210.degree. C. for 2 minutes. 
(4) Turn off heat. Cooling in place under 20 tons with cooling water to 
room temperature (.about.15 minutes). 
(5) Release pressure and remove specimens from the mold. 
SPECIMEN CONDITIONING AND TESTING 
All 73.degree. F. testing specimens were conditioned at 73.degree. F. and 
50% relative humidity at least overnight before testing. The -40.degree. 
F. testing specimens were cooled in a freezer at -40.degree. F. overnight 
before testing. 
Notched Izod impact testing was conducted according to ASTM D256 Method A. 
An Izod tester by Testing Machines, Inc. was used. Gardner drop-weight 
impact tests were also conducted. Two Gardner drop-dart impact testers 
were used. One Gardner tester (a) consisted of a 4-lb. dart with a 1/2" 
diameter round tip, and specimen support with a 5/8" hemispherical hole in 
line with the dart. The other Gardner tester (b) was equipped with an 
8-lb. dart (1/2" diameter, round top) and a specimen support with a 11/4" 
hole. The Bruceton staircase method (Moritz, W. J., "Fair-Sensitivity 
Criterion for Evaluating Falling Dart-Impact Tests", Modern Plastics, 60, 
Nov. 1975) was used for calculating energy at 50% failure. 
The results of the various operations are set forth in the following Tables 
I-III. (All data are from compression molded samples, all % are by 
weight), and the concentrate source identified is as indicated in Example 
1 above): 
TABLE I 
__________________________________________________________________________ 
EFFECT OF CARBON BLACK ON IMT STRENGTH OF ABS 
Notched Izod Impact.sup.a 
Gardner Impact 
Carbon Black % (Ft-Lb/In) (In-Lb) 
Sample No. 
(Concentrate Source) 
73.degree. F. 
-40.degree. F. 
73.degree. F. 
-40.degree. F. 
__________________________________________________________________________ 
ABS-1.sup.d 
0 3.5 .+-. 0.2 
1.8 .+-. 0.1 
54.sup.b 
41.sup.b 
ABS-1 
0.35 2.4 .+-. 0.1 
1.3 .+-. 0.3 
37.sup.b 
27.sup.b 
(SBC #1) 
ABS-2.sup.e 
0 7.4 .+-. 0.3 
3.0 70.sup.b 
64.sup.b 
ABS-2 
0.35 5.4 .+-. 0.3 
1.9 .+-. 0.2 
51.sup.b 
36.sup.b 
(SBC #1) 
ABS-3.sup.f 
0 6.5 .+-. 1.0 
2.0 .+-. 0.1 
189 .+-. 9.sup.c 
83 .+-. 3.sup.c 
ABS-3 
0.35 4.6 .+-. 0.1 
1.8 .+-. 0.1 
-- -- 
(SBC #1) 
" 0.35 5.8 .+-. 0.5 
1.7 .+-. 0.1 
121 .+-. 12.sup.c 
65 .+-. 4.sup.c 
(SBC # 2) 
" 0.35 5.1 .+-. 0.2 
1.7 .+-. 0.1 
-- -- 
(EBC #1) 
" 0.35 5.1 .+-. 0.1 
1.7 .+-. 0.1 
148 .+-. 7.sup.c 
83 .+-. 3.sup.c 
(EBC #2) 
__________________________________________________________________________ 
.sup.a Average of 5 specimens. The .+-. values indicate 95% confidence 
limits. For converting to SI unit: 1 ftlb/in = 53.3787 J/m. 
.sup.b Energy at 50% failure of 16 tests using the Gardner tester (a). Th 
nominal specimen thickness is 0.075 in. 
.sup.c Energy at 50% failure of 20 specimens (30) specimens for 
-40.degree. F.) tested on Gardner tester (b). Nominal specimen size: 2" 
.times. 2" .times. 0.15". The .+-. values indicate 95% confidence limits. 
.sup.d ABS1 resin = nominally 23% acrylonitrile, 15% rubber, 60% styrene. 
.sup.e ABS2 resin = nominally 23% acrylonitrile, 17% rubber, 58% styrene. 
.sup.f ABS3 resin = nominally 22% acrylonitrile, 19% rubber, 57% styrene. 
The detrimental effect of carbon black on the impact strength and toughness 
of each of the ABS resins is clearly shown in Table I. All three ABS 
resins decreased considerably in impact strength when 0.35% of carbon 
black was added. This undesirable effect on impact strength and toughness 
is evidenced by both notched Izod impact and Gardner drop dart impact data 
of the materials at both 73 and -40.degree. F. The ABS designations in the 
following tables are as noted in Table I. 
In Table II, SBC, EBC and NRBC compositions were evaluated with ABS-3. 
These results also show the same trend with ABS-3 as for ABS-1 and ABS-2, 
i.e., that NRBC has a remedial as well as an improved effect on the 
detrimental behavior of carbon black on the impact strength/toughness of 
ABS resins. 
TABLE II 
__________________________________________________________________________ 
COMISON OF THE IMT STRENGTH TOUGHNESS 
OF ABS-3 WITH OR WITHOUT CARBON BLACK 
IN THE PRESENCE OR ABSENCE OF NITRILE RUBBER 
% Carbon Black % Notched Izod Impact.sup.b 
Gardner Impact.sup.c 
(Concentrate Nitrile 
(Ft-Lb/In) (In-Lb) 
Sample No. 
Source) Rubber.sup.a 
73.degree. F. 
-40.degree. F. 
73.degree. F. 
-40.degree. F. 
__________________________________________________________________________ 
ABS-3 
0 0 6.5 .+-. 1.0 
2.0 .+-. 0.1 
182 .+-. 9 
83 .+-. 3 
" 0.35 0 5.8 .+-. 0.5 
1.7 .+-. 0.1 
121 .+-. 12 
65 .+-. 4 
(SBC-#1) 
" 0.35 0 5.1 .+-. 0.1 
1.7 .+-. 0.1 
148 .+-. 7 
83 .+-. 3 
(EBC-#2) 
" 0.35 0 5.1 .+-. 0.2 
1.7 .+-. 0.1 
-- -- 
(EBC-#1) 
" 0.35 5.04 8.9 .+-. 0.4 
2.5 .+-. 0.1 
214 .+-. 11 
111 .+-. 6 
(NRBC-#1) 
" 0.35 3.50 8.9 .+-. 0.3 
2.2 .+-. 0.1 
239 .+-. 5 
124 .+-. 6 
(NRBC-#2) 
__________________________________________________________________________ 
.sup.a Nitrile Rubber = Hycar 1053. 
.sup.b Average of 5 specimens. The .+-. values represent 95% confidence 
limits. For converting to SI unit: 1 ftlb/in = 53.3787 J/m. 
.sup.c Energy at 50% failure of 16 tests using Gardner tester (a). The 
nominal specimen thickness is 0.075". 
Two ABS resins (#2 and #3) were melt-blended with either an NRBC 
concentrate or NR and a conventional black concentrate (SBC or EBC). 
Impact data show that the resulting blends from all operations are 
comparable in impact strength/toughness (Table III). Thus, NR minimizes 
the detrimental effect of carbon black on the impact strength/toughness of 
ABS resins (note control data for ABS-#2 and ABS-#3 in previous Tables I 
and II), regardless whether carbon black was added as a concentrate premix 
with the NR or added to the ABS resin before or after separate NR 
addition. 
TABLE III 
__________________________________________________________________________ 
COMISON OF THE IMT STRENGTH/TOUGHNESS OF ABS 
WITH EITHER NITRILE RUBBER CARBON BLACK CONCENTRATE 
OR CARBON BLACK CONCENTRATE PLUS NITRILE RUBBER 
% Carbon Black % Notched Izod Impact.sup.b 
Gardner Impact.sup.c 
(Concentrate Nitrile 
(Ft-Lb/In) (In-Lb) 
Sample No. 
Source) Rubber.sup.a 
73.degree. F. 
-40.degree. F. 
73.degree. F. 
-40.degree. F. 
__________________________________________________________________________ 
1. ABS-#2 
0.35 5 8.8 .+-. 1.1 
3.1 .+-. 0.4 
78.sup.c 
52.sup.c 
(SBC-#1) 
2. ABS-#3 
0.35 5 8.9 .+-. 0.4 
2.5 .+-. 0.1 
214 .+-. 11.sup.d 
111.+-. 6.sup.d 
(NRBC-#1) 
3. ABS-#3 
0.35 5 8.9 .+-. 0.5 
2.4 .+-. 0.1 
251 .+-. 5.sup.d 
119 .+-. 4.sup.d 
(EBC-#2) 
__________________________________________________________________________ 
.sup.a Hycar 1053, added separately in Samples 2 and 4. 
.sup.b Average of 5 specimens. The .+-. values indicate 95% confidence 
limits. For converting to SI unit: 1 ftlb/in = 53.3787 J/m. 
.sup.c Energy at 50% failure of 16 tests using the old tester. The nomina 
specimen thickness is 0.075". 
.sup.d Energy at 50% failure of 20 specimens (30 specimens for -40.degree 
F.) tested on the Gardner tester (b). Nominal specimen dimensions: 2" 
.times. 2" .times. 0.15". The .+-. values indicate 95% confidence limits. 
EXAMPLE 3 
In other operations, the butadiene-acrylonitrile rubbery copolymer 
additives of the present invention were evaluated in side-by-side tests 
with other rubber additives and samples of the compositions impact tested. 
As is apparent from the data set forth in Table IV below, both the Gardner 
and notched Izod impact strengths of the blend composition containing 
carbon black were restored and increased when a nitrile rubber of the 
present invention was employed, but were even further reduced below the 
control sample impact strengths when other rubber copolymer additives were 
employed. The data thus establish the nitrile rubbers of the present 
invention appear to be unique as to the restoration and improvement in 
toughness of ABS-type resins containing carbon black. 
TABLE IV 
______________________________________ 
COMISON OF THE IMT STRENGTH/TOUGHNESS 
OF CARBON BLACK ABS MELT-BLENDED 
WITH VARIOUS RUBBERS 
Notched 
Rubber 
Izod Impact.sup.a 
Gardner Impact .sup.b 
Addi- (Ft-Lb/In) (In-Lb) 
Sample No. 
tive % 73.degree. F. 
-40.degree. F. 
73.degree. F. 
-40 .degree. F. 
______________________________________ 
1. ABS-#2- 0 5.4 .+-. 0.3 
1.9 .+-. 0.2 
51 36 
SBC #1.sup.c 
2. ABS-#2- 5.0.sup.d 
8.8 .+-. 1.1 
3.1 .+-. 0.4 
78 52 
SBC #1.sup.c 
3. ABS-#2- 5.0.sup.e 
2.7 .+-. 0.3 
1.3 .+-. 0.3 
19 6 
SBC #1.sup.c 
4. ABS-#2- 5.0.sup.f 
2.4 35 1.0 .+-. 0.1 
24 8 
SBC #1.sup.c 
______________________________________ 
.sup.a Average of 5 specimens injection molded. The .+-. values indicate 
95% confidence limits. For converting to SI unit = 1 ftlb/in = 53.3787 
J/m. 
.sup.b Energy at 50% failure of 16 tests using tester a. The nominal 
specimen thickness is 0.075". 
.sup.c ABS# 2/SBC#1 ratio = 99:1; 0.35% carbon black in final composition 
.sup.d Butadiene (71%)acrylonitrile (29%) copolymer. 
.sup.3 Oil extended copolymer comprising about 1/3 mineral oil, 2/3 
stryene (30%) and butadiene (70%). 
.sup.f Stryrene (30%)butadiene (70%) block copolymer. 
EXAMPLE 4 
In further operations, the use of NRBC in improving the blendability, e.g., 
of a high-impact strength ABS resin with a low-impact strength ABS resin 
(as is often done in the industry for purposes of economy) was evaluated 
to determine if the proportion of the low-impact resin utilized in such 
blends could be increased without sacrificing desired impact strength 
properties of the blend. In these operations, a high impact resin (ABS-3) 
and a low impact resin ABS-4 (about 15-19% acrylonitrile, about 7-9% 
rubber, balance styrene including about 1-1.5% additives). All final 
blends contained 0.35% carbon black and 0.325% nitrile rubber. The results 
of the various tests are set forth below in Table V: 
TABLE V 
______________________________________ 
COMISON OF THE IMT STRENGTH OF 
ABS-3/ABS-4 MELT-BLENDED 
WITH 1% CARBON BLACK CONCENTRATE OR 
NITRILE RUBBER CARBON BLACK CONCENTRATE 
Injection Molded 
Compression 
Notched Molded 
ABS-3/ Black Izod Impact.sup.a 
Gardner Impact.sup.b 
ABS-4 Concentrate 
(Ft-Lb/In) (In-Lb) 
Ratio Type 73.degree. F. 
-40.degree. F. 
73.degree. F. 
-40.degree. F. 
______________________________________ 
1. 60/40 
EBC #1 6.2 .+-. 0.2 
1.8 .+-. 0.2 
71 .+-. 10 
42 .+-. 4 
2. 50/50 
EBC #1 5.4 .+-. 0.2 
1.6 .+-. 0.3 
54 .+-. 6 
31 .+-. 3 
3. 50/50 
NRBC-#3 6.1 .+-. 0.4 
1.6 .+-. 0.2 
79 .+-. 5 
43 .+-. 4 
4. 40/60 
NRBC-#3 5.2 .+-. 0.3 
1.7 .+-. 0.2 
55 .+-. 4 
31 .+-. 4 
______________________________________ 
.sup.a Average of 5 specimens. The .+-. indicate 95% confidence limits. 
For converting to SI unit: 1 ftlb/in = 53.3787 J/m. 
.sup.b Energy at 50% failure of 20 specimens (30 specimens for -40.degree 
F.) tested on the Gardner tester (b). Nominal specimen dimensions: 2" 
.times. 2" .times. 0.15". The .+-. values indicate 95% confidence limits. 
The foregoing data indicate that the concentration or ratio of the low 
impact strength ABS-4 resin in the total composition can be increased by 
about 10% even by the addition of a very low amount (0.325 wt. %) nitrile 
rubber to the composition. For example, the impact strengths of the 
composition of Sample No. 3 (50/50 ratio), mixed with only a very low 
amount (0.325%) of nitrile rubber, are comparable with those of the 60/40 
resin of Sample No. 1, even though the Sample No. 3 composition contains 
10% more of the low-impact ABS-4 resin. Similar results are indicated for 
Sample No. 4, which contains 10% more of the low-impact ABS-4 resin than 
the Sample No. 2 composition. As is apparent from the above, the NR 
addition not only overcomes the detrimental effect of carbon black 
evidenced in preceding examples, but also allows the blending of greater 
amounts of low-impact resins without substantially affecting the desired 
impact strength of the final blend. Blends incorporating even greater 
amounts of the low impact resin while maintaining the desired blend impact 
strength, or blends having improved impact strength, can be obtained by 
using increased amounts of the NR.