Compositions derived from recycled polymers

Resinous compositions are prepared by blending an ABS copolymer or similar addition polymer, a polyphenylene ether-polystyrene blend, and a copolymer of an olefin such as ethylene and an epoxy compound such as glycidyl methacrylate. The first two constituents may be scrap materials. The resulting compositions have high impact strength and other advantageous properties.

This invention relates to recycled thermoplastic resins, and more 
particularly it relates to blends of a copolymer derived from an 
alkenylaromatic compound and a polymerizable nitrile and a composition 
comprising polyphenylene ether and poly(alkenylaromatic) resins. 
Countless pounds of plastic in the form of business machines, automobile 
interiors and the like are being sold to consumers every day. This results 
in hundreds of millions of pounds of non-biodegradable thermoplastic and 
some thermoset resin scrap that must be disposed of each year. For 
environmental reasons, it would be highly desirable to find additional 
uses for this large and ever growing amount of plastic waste, such as 
recycle of the scrap resin into useful products. 
Often the discarded items are made from incompatible resins. For example, 
business machines sold by one company may have housings made from an ABS 
(acrylonitrile-butadiene-styrene) resin, while business machines sold by 
another company may have housings made from a polyphenylene 
ether/polystyrene blend, the two of which are incompatible materials. For 
economic and environmental reasons, it would be desirable to find ways to 
process such incompatible scrap resins without sorting. 
Therefore, the present invention provides a composition prepared from the 
incompatible plastic resin, both virgin and scrap, capable of being molded 
into shaped articles which exhibit excellent mechanical properties. 
In one of its aspects, the present invention is a method for preparing a 
resinous composition which comprises blending under reactive conditions: 
(A) a virgin or scrap copolymer of at least one alkenylaromatic monomer, at 
least one of acrylonitrile and methacrylonitrile and at least one 
aliphatic diene; 
(B) a virgin or scrap thermoplastic composition comprising at least one 
polyphenylene ether resin and at least one poly(alkenylaromatic) resin; 
and 
(C) a copolymer of at least one ethylenically unsaturated epoxy compound 
and at least one olefin; 
the proportions of components A and B each being in the range of about 
1-95% and the proportion of component C in the range of about 5-40% by 
weight, based on the total of A and B. Another aspect of the invention is 
compositions prepared by said method. 
Component A according to the present invention is a copolymer of at least 
one alkenylaromatic monomer, at least one of acrylonitrile and 
methacrylonitrile and at least one aliphatic diene. Said copolymer may be 
virgin (i.e., freshly prepared) or a scrap or recycled copolymer. The 
invention is particularly advantageous for use with scrap copolymers of 
this type, by reason of its capability of improving the properties of 
blends containing such scrap polymers. 
Illustrative of the alkenylaromatic units which may be present in component 
A are those having the formula 
##STR1## 
wherein each of R.sup.1 and R.sup.2 is hydrogen or C.sub.1-6 alkyl, each 
of R.sup.3 and R.sup.4 is independently chloro, bromo, hydrogen or 
C.sub.1-6 alkyl, and each of R.sup.5 and R.sup.6 is independently hydrogen 
or C.sub.1-6 alkyl or R.sup.5 and R.sup.6 together with the atoms to which 
they are attached form a fused benzene ring. Suitable alkenylaromatic 
compounds include, for example, styrene and its analogs, such as a-methyl 
styrene, chloro- and bromostyrenes, 3,5 dimethylstyrene and 
t-butylstyrene. 
Also present in component A are units derived from at least one aliphatic 
diene such as butadiene, isoprene or chloroprene. Butadiene is usually 
preferred. 
Other structural units may also be present in component A. They include 
units derived from such ethylenically unsaturated monomers as methyl 
methacrylate, methyl acrylate, acrylic acid, methacrylic acid, acrylamide, 
methacrylamide, vinyl chloride, ethyl vinyl ether and maleic anhydride. 
Polymers useful as component A may be prepared by methods well known in the 
art, including emulsion, bulk and melt polymerization. A common method for 
preparing such polymers includes a first step of polymerizing the diene 
monomer or monomers in emulsion to form a latex, and subsequent grafting 
of the alkenylaromatic and nitrile monomers and any other monomers on said 
latex, also in emulsion. 
The resulting graft copolymer generally contains diene structural units in 
the amount of about 5-30% by weight, with the balance being grafted 
moieties containing the other structural units. Grafted structural units 
derived from the alkenylaromatic compound and nitrile generally comprise 
about 65-80% and about 20-35%, respectively, by weight of total grafted 
units. Other monomer units, if present, constitute up to about 20% of 
total grafted units. 
Component B is a virgin or scrap thermoplastic composition, also preferably 
scrap. It comprises a polyphenylene ether resin and a 
poly(alkenylaromatic) resin, the latter of which typically comprises 
structural units of formula I. 
The polyphenylene ethers are known polymers comprising a plurality of 
structural units of the formula 
##STR2## 
In each of said units independently, each Q.sup.1 is independently 
halogen, primary or secondary lower alkyl (i.e., alkyl containing up to 7 
carbon atoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or 
halohydrocarbonoxy wherein at least two carbon atoms separate the halogen 
and oxygen atoms; and each Q.sup.2 is independently hydrogen, halogen, 
primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy or 
halohydrocarbonoxy as defined for Q.sup.1. Most often, each Q.sup.1 is 
alkyl or phenyl, especially C.sub.1-4 alkyl, and each Q.sup.2 is hydrogen. 
Both homopolymer and copolymer polyphenylene ethers are included. The 
preferred homopolymers are those containing 2,6-dimethyl-1,4-phenylene 
ether units. Suitable copolymers include random copolymers containing such 
units in combination with (for example) 2,3,6-trimethyl-1,4-phenylene 
ether units. Also included are polyphenylene ethers containing moieties 
prepared by grafting onto the polyphenylene ether in known manner such 
materials as vinyl monomers or polymers such as polystyrenes and 
elastomers, as well as coupled polyphenylene ethers in which coupling 
agents such as low molecular weight polycarbonates, quinones, heterocycles 
and formals undergo reaction in known manner with the hydroxy groups of 
two polyphenylene ether chains to produce a higher molecular weight 
polymer, provided a substantial porportion of free OH groups remains. 
The polyphenylene ether generally has a number average molecular weight 
within the range of about 3,000-40,000 and a weight average molecular 
weight within the range of about 20,000-80,000, as determined by gel 
permeation chromatography. Its intrinsic viscosity is most often in the 
range of about 0.15-0.6 dl./g., as measured in chloroform at 25.degree. C. 
The polyphenylene ethers are typically prepared by the oxidative coupling 
of at least one monohydroxyaromatic compound such as 2,6-xylenol or 
2,3,6-trimethylphenol. Catalyst systems are generally employed for such 
coupling; they typically contain at least one heavy metal compound such as 
a copper, manganese or cobalt compound, usually in combination with 
various other materials. 
Particularly useful polyphenylene ethers for many purposes are those which 
comprise molecules having at least one aminoalkyl-containing end group. 
The aminoalkyl radical is typically located in an ortho position to the 
hydroxy group. Products containing such end groups may be obtained by 
incorporating an appropriate primary or secondary monoamine such as 
di-n-butylamine or dimethylamine as one of the constituents of the 
oxidative coupling reaction mixture. Also frequently present are 
4-hydroxybiphenyl end groups, typically obtained from reaction mixtures in 
which a by-product diphenoquinone is present, especially in a 
copper-halide-secondary or tertiary amine system. A substantial proportion 
of the polymer molecules, typically constituting as much as about 90% by 
weight of the polymer, may contain at least one of said 
aminoalkyl-containing and 4-hydroxybiphenyl end groups. 
It will be apparent to those skilled in the art from the foregoing that the 
polyphenylene ethers contemplated for use in the present invention include 
all those presently known, irrespective of variations in structural units 
or ancillary chemical features. 
The poly(alkenylaromatic) resin comprises structural units of formula I 
hereinabove, optionally in combination with other units. Included are 
rubber-modified polystyrenes. Suitable modifiers include natural and 
synthetic rubbers such as polyisoprene, polybutadiene, polychloroprene, 
ethylene-C.sub.3-10 monoolefin-diene terpolymers (EPDM rubber), 
styrene-butadiene copolymers (SBR rubber), styrene-acrylonitrile 
copolymers (SAN), ethylene-propylene copolymers (EP rubbers), polyurethane 
rubbers, and polyorganosiloxane (silicone) rubbers. The rubber content 
will generally be up to about 45 percent by weight, depending on the 
particular requirements of impact resistance modification desired. 
Since polyphenylene ethers and poly(alkenylaromatic) resins are miscible in 
all proportions, the proportions thereof in component B are not critical. 
In general, weight ratios of poly(alkenylaromatic) resin and polyphenylene 
ether are between about 5:95 and 95:5. 
Component C is a copolymer of at least one ethylenically unsaturated epoxy 
compound and at least one olefin. The olefins are illustrated by ethylene, 
propylene and 1-butene, with ethylene being preferred. 
Suitable epoxy structural units in component C include those having the 
formula 
##STR3## 
wherein R.sup.10 is a radical containing an epoxy group and each R.sup.9 
is independently hydrogen, C.sub.1-8 alkyl, C.sub.6-13 cycloalkyl or aryl, 
or aralkyl. Such compounds include glycidyl ethers of unsaturated alcohols 
such as allyl glycidyl ether, glycidyl ethers of alkenylphenols such as 
vinylphenyl glycidyl ether, vinyl and allyl esters of epoxy carboxylic 
acids such as vinyl epoxystearate, and glycidyl esters of unsaturated 
carboxylic acids, e.g., glycidyl methacrylate, glycidyl 2-ethylacrylate, 
glycidyl 2-propylacrylate and glycidyl acrylate. Glycidyl methacrylate 
(GMA) is preferred. 
Component C may also contain units derived from other ethylenically 
unsaturated monomers, especially vinyl esters as illustrated by vinyl 
acetate. 
The proportions of structural units in component C will generally be about 
70-95% olefin units and about 5-30% epoxy-containing units, by weight of 
said component. If other units are present, they will generally be in the 
amount of about 2-10%. 
As previously mentioned, the proportions of components A and B are each in 
the range of about 1-95% by weight; preferred proportions are about 50-75% 
A and about 25-50% B. The proportion of component C, on the same basis, is 
in the range of about 5-40%; it is preferably about 5-15% since impact 
strengths of the compositions of the invention are often maximized in that 
range. 
Components A and B may optionally also comprise up to about 40 percent by 
weight of filler material. Suitable filler materials include particulate 
and fibrous reinforcing agents, preferably glass fibers. 
According to the invention, components A, B and C are blended under 
reactive conditions. Such conditions may comprise solution or melt 
blending, typically at temperatures in the range of about 
200.degree.-300.degree. C. Melt blending is usually preferred by reason of 
its particular applicability and the availability of melt blending 
equipment in polymer processing facilities. Conventional melt blending 
apparatus of both the batch and continuous type may be employed. 
Typically, melt blending is effected by extrusion.

The invention is illustrated by the following examples. All parts, 
proportions and percentages are by weight. 
EXAMPLES 1-4 
Two reclaimed (scrap) polymer compositions were employed: an ABS copolymer 
and a blend of poly(2,6-dimethyl-1,4-phenylene ether) and polystyrene. The 
precise natures and proportions of structural units and polymers in these 
compositions are not known with certainty, since they were recovered from 
previous use. However, said proportions are known to be within the broad 
definitions provided hereinabove. 
The two polymer compositions were blended in a 2:1 ratio of ABS to 
polyphenylene ether-polystyrene, and the blend was granulated and extruded 
with either of two commercially available copolymers containing ethylene 
and glycidyl methacrylate units and, in Examples 3 and 4, vinyl acetate 
units. Extrusion was conducted in a twin screw extruder at about 
250.degree. C. The extrudates were pelletized and dried at 85.degree. C., 
and the dried blends were injection molded at about 250.degree. C. into 
test specimens which were evaluated for tensile elongation and impact 
properties, in comparison with a control containing only the ABS and 
polyphenylene ether-polystyrene blend. The results are given in the 
following table. 
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Example 
1 2 3 4 Control 
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Component C: 
Ethylene units 88 88 83 83 -- 
Glycidyl methacrylate units 
12 12 12 12 -- 
Vinyl acetate units 
-- -- 5 5 -- 
Percent (based on A + B + C) 
10 20 10 20 -- 
Tensile elongation, % 
20 39 15 65 17 
Notched Izod impact 
59 43 59 48 37 
strength, joules/m. 
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It will be apparent that the impact strengths of the compositions of this 
invention are substantially higher than that of the control, and tensile 
elongations are generally higher or at least equivalent. Maximum impact 
strengths are obtained when the proportion of component C is in the 
preferred 5-15% range.