Molding compositions comprising polyphenylene ether, polysulfone and vinyl aromatic-diene block copolymer

Molding compositions comprising a polyphenylene ether, a polysulfone, and a selectively hydrogenated linear or radial block copolymer comprising vinyl aromatic compound and dienes, optionally further including a plasticizer, possess excellent impact resistance, and heat aging resistance.

The present invention relates to novel molding compositions based on 
polyphenylene ether--polysulfone modified by a content of a block polymer 
as agent imparting superior physical properties to molded articles 
prepared therefrom. The invention includes the novel molding compositions 
themselves with and without conventional molding composition additives, 
methods of preparing the compositions, molded articles made from the 
compositions, and methods of making the moldings. 
BACKGROUND OF THE INVENTION 
From Netherlands patent publication No. 6716106, it is known that molding 
compositions based on one or more of the thermoplastic polyphenylene 
ethers and one or more of the thermoplastic polysulfones, when molded at 
elevated temperature and pressure, provide shaped articles which possess 
very satisfactory impact strength. However, samples molded from such 
compositions show phase incompatibility in differential scanning 
calorimetry tests and the moldings are laminar. It is obvious if this 
shortcoming is avoided, then the compositions will provide molded articles 
which are superior in the above respects. It has now been discovered that 
the impact properties and heat age resistance is increased, and lamination 
is decreased or even eliminated, when the molding composition has a 
content of a selectively hydrogenated linear or radial thermoplastic block 
copolymer which consists essentially of vinyl aromatic compound, e.g., 
styrene and a diene, e.g. butadiene. 
It has further been found that properties, especially impact strength and 
processability can be further improved by adding an effective amount of a 
plasticizer, e.g. triphenyl phosphate. The preferred plasticizers also 
function to enhance the flame retardancy of the new compositions. 
Suitable block copolymers are commercially available at low cost. The 
present invention thus substantially expands the field of utility of 
polyphenylene ether--polysulfone moldings in an economical way. 
DESCRIPTION OF THE INVENTION 
According to the present invention, there are provided molding compositions 
comprising a polyphenylene either, a polysulfone, and an impact improving 
amount of a selectively hydrogenated block copolymer of the linear or 
radial teleblock type comprising blocks of polymerized vinyl aromatic 
compound and blocks of polymerized diene. The polyphenylene ethers (also 
termed "polyphenylene oxides" and "PPO") are known as a class (see Hay 
U.S. Pat. Nos. 3,306,874 and 3,306,875 and Stamatoff U.S. Pat. Nos. 
3,257,357 and 3,257,358, which disclose a number of suitable members of 
the class and methods for their preparation). They are composed of 
repeating units having the theoretical formula: 
##STR1## 
wherein the oxygen ether atom of one unit is connected to the benzene 
nucleus of the next repeating unit, n is a positive integer and is at 
least 50, and each Q is a monovalent substituent selected from the group 
consisting of hydrogen, halogen, hydrocarbon radicals free of a tertiary 
.alpha.-carbon atom, halohydrocarbon radicals having at least two carbon 
atoms between the halogen atom and phenyl nucleus and being free of a 
tertiary .alpha.-carbon atom, and halohydrocarbonoxy radicals having at 
least 2 carbon atoms between the halogen atom and phenyl nucleus and being 
free of tertiary .alpha.-carbon atom. 
The polymer can contain minor percentages of other units so long as these 
units do not significantly alter the essential character of the polymer. 
Examples of suitable polymers in this group are disclosed in the 
above-identified patents and additional suitable polyphenylene ethers can 
be prepared in accordance with the methods shown there. Polymers in which 
the Q's in the 2,6-position are alkyl of from 1 to 4 carbon atoms, the 
remaining Q's being hydrogen, are preferred. 
Poly-(2,6-dimethyl-1,4-phenylene) ether is especially preferred because of 
its very satisfactory compatibility with the other components of the 
composition. The latter polymer is commercially available, e.g., from 
General Electric Co., Pittsfield, Mass. 
The polysulfones which are present in the compositions of the present 
invention are also a known class and can be prepared by reacting the 
sodium salt of a bis(hydroxyphenyl)propane with an equimolar quantity of a 
dichlorodiphenyl sulfone. See The Encyclopedia of Polymer Science and 
Technology, Vol. 11, New York, Interscience Publishers, 1969, pages 
447-463, the disclosure of which is incorporated herein by reference. 
When the reaction is performed with 2,2-bis(4-hydroxyphenyl)propane and 
4,4'-dichlorodiphenyl sulfone, a linear polymer is obtained which is 
composed of, typically, from 50 to 80 of the following recurring units: 
##STR2## 
The polymerization can be terminated at any desired point by adding a 
monofunctional chain stopper, for example methyl chloride. The molecular 
weight of the polymer can thereby be controlled, with production of a 
polymer of good thermal stability. 
The polymer when molded forms rigid strong thermoplastic pieces which are 
resistant to deflection by heat up to 345.degree. F. and which are 
sufficiently stable to permit their continuous use in the atmosphere at 
temperatures up to 300.degree. F. They can be heated to 500.degree. F. for 
brief periods of time without significant degradation. 
The phenyl and methyl groups in the formula given above can carry inert 
thermostable substituents, for example methoxy, ethoxy, carbethoxy, 
carbomethoxy, phenyl and diethylamino, in moderate number so long as these 
groups do not change the essential character of the polymer, or increase 
the flow point of the polymer substantially above the flow point of the 
polyphenylene ether. A suitable commercial material is the product of 
Union Carbide Co. known as Polysulfone P 1700. 
As has been mentioned, the polysulfones are significantly effective in 
increasing the impact resistance of polyphenylene ether moldings when they 
are present in minor proportions. In the compositions of the present 
invention, therefore, the polysulfone is present in such proportion that 
the weight of the polysulfone ranges from 15 to 50 parts per 100 parts of 
combined polysulfone, polyphenylene ether and block copolymer. 
The block copolymers which are the third principal component of the 
compositions of the present invention are linear or radial teleblock 
copolymers which are substantially composed of blocks of vinyl aromatic 
compounds, e.g., styrene or substituted styrenes, and blocks of diene, 
e.g., butadiene or isoprene. The latter blocks are the selectively 
hydrogenated in a post polymerization reaction which saturates the 
residual bonds of the polymerized diene blocks with hydrogen. The styrene 
blocks and the saturated rubber blocks are present in weight ratio between 
90:10 and 10:90, depending on the properties desired, the styrene blocks 
generally providing stiffness and the saturated rubber blocks generally 
providing toughness. The intermediate ratio of 30:70 (styrene-butadiene) 
has given very satisfactory results and is therefore preferred. The block 
copolymers are linear or branched, (radial teleblock). 
The styrene blocks may contain components such as .alpha.-methylstyrene, 
.alpha.-chlorostyrene, o-methylstyrene, an acrylonitrile. 
The saturated rubber blocks may be blocks of staturated polyisoprene or 
saturated polychloroprene, but blocks of saturated butadiene are preferred 
because of the very satisfactory elastomeric properties which these blocks 
impart. 
Block copolymers having selectively hydrogenated conjugated diene blocks 
are disclosed in Wald et al., U.S. Pat. No. 3,595,942, incorporated herein 
by reference. Block polymers which are suitable for use in the 
compositions of the present invention are sold under the trademarks 
Solprene 502, (Phillips), Kraton G-1651 and G-1652 (Shell). Kraton G-1651 
and 1652 are linear block copolymers containing an elastomeric center 
block of hydrogenated poly-butadiene, and their end blocks are 
polystyrene; Solprene 502 is a radial teleblock copolymer of styrene and 
hydrogenated polybutadiene. 
The polyphenylene ether and the polysulfone are respectively present in the 
compositions of the present invention in weight ratio between 99:1 and 
1:99, again depending on the physical properties which are desired. The 
best combination of physical properties from the point of view of tensile 
strength, elongation and impact resistance appear to be obtained when a 
moderate amount of the polysulfone is present, and therefore the ratio 
range of 85:15 to 50:50 is preferred. 
In preferred compositions, there will also be present a small, effective 
amount of a plasticizer. This will generally comprise a high boiling 
liquid which serves to improve processability, without at the same time 
lowering important properties in articles ultimately molded therefrom. 
Although many such plasticizers are known to be suitable for this purpose, 
it is preferred to use a phosphate compound, e.g., a triaryl phosphate 
such as triphenyl phosphate, tri-o-cresyl phosphate, and the like. These, 
in addition to their plasticizing effect also serve to enhance the 
self-extinguishing characteristics of the composition. Conventional 
amounts of plasticizer will be used, e.g., from 10 to 30 parts by weight 
per 100 parts by weight total of the compositions. 
The auxiliary materials which are frequently present in thermoplastic 
molding compositions can be added at any convenient point in the mixing 
operation. These auxiliary materials include pigments such as ultramarine 
blue, titanium dioxide white, and carbon black; flame retardants; 
antioxidants; plasticizers; fillers such as whiting; and fibrous 
strengtheners such as asbestos fibers and glass fibers. Generally these 
materials are most conveniently added while the polymeric components are 
being mixed. If preferred, however, the auxiliary agents can be added to 
one of the components before the component is mixed with the other 
components, or they can be divided and added to two or to each of the 
components before the step where all the components are mixed together. 
Thus the materials can be added to a mixture of the polyphenylene ether 
and the polysulfone, before addition of the block copolymer. The 
proportions in which these materials are added are conventional and are 
not features of the invention. 
The compositions can be made and molded in conventional ways. For example, 
the ingredients can be extrusion blended and chopped to produce molding 
pellets. The molding pellets can then be used in a suitable injection 
molding machine.

The invention is further described in the examples which follow. These 
examples are preferred embodiments of the invention, and are not to be 
constued in limitation thereof. 
EXAMPLES 1-4 
Compositions according to this invention is prepared by extruding the 
ingredients set forth in a 28 mm. Werner-Pfleiderer extruder at 
550.degree. F. and chopping the extrudate into pellets. The pellets are 
injection molded into test samples in a 3 oz. Newbury machine at 
520.degree. F. (cylinder) and 190.degree. F. (mold). For examplary 
purposes, compositions with a plasticizer/flame retardant are also 
prepared, molded and tested. The results are set forth in the Table. 
TABLE 
______________________________________ 
Composition Comprising Polyphenylene Ether, Polysulfone, 
and Block Copolymer 
Example 
1 2 3 4 
______________________________________ 
Composition (parts by weight) 
Poly(2,6-dimethyl-1,4-phenylene) 
45 45 60 60 
ether.sup.a 
Polysulfone.sup.b 40 40 20 20 
Selectively hydrogenated block co- 
15 15 20 20 
polymer of styrene and butadiene.sup.c 
Plasticizer, triphenyl phosphate 
-- 10 -- 10 
Properties 
Tensile elongation, % 
23 41 37 55 
Izod impact strength, ft.-lbs./in. notch 
1.0 2.6 1.4 18.4 
Gardner impact strength, in.-lbs. 
&lt;10 130 10 240 
Deflection temp. under load, .degree.F. 
N.D.* 259 N.D. 243 
at 260 psi. 
Flammability rating, Underwriters' 
N.D. SE-0 N.D. SE-1 
Laboratory, Bulletin 94 
______________________________________ 
*N.D.--not determined 
.sup.a General Electric Co., PPO 
.sup.b Union Carbide P1700 
.sup.c Shell Chemical, Kraton G 
The results show the beneficial effect of including the plasticizer. 
Especially noteworthy is the high impact strength in the notched Izod test 
for Example 4. In addition to the foregoing improved properties, the 
present compositions should heat age quite well. 
Obviously, many variations will suggest themselves to those skilled in this 
art in light of the above, detailed disclosure. For example, the 
plasticizer can be omitted, and flame retardants, stabilizers, fillers, 
reinforcements, etc., can be added. In addition, compatible resins, such 
as polystyrenes particularly rubber modified high impact polystyrenes can 
be added. All such obvious variations are within the full intended scope 
of the appended claims.