Novel resin compositions based on polyphenylene ether

A resin composition based on a polyphenylene ether comprising 99 to 1 part by weight of a polyphenylene ether copolymer derived from 99.5 to 85 mole-% of 2,6-dimethylphenol and 0.5 to 15 mole-% of 3-methyl-6-tert-butylphenol and 1 to 99 parts by weight of a styrene polymer (making up 100 parts by weight in total); and said resin composition further containing 0.1 to 100 parts by weight of a rubber-like polymer for 100 parts by weight of the said resin composition. These resin compositions have excellent mechanical strength, heat resistance, and moldability and are suitable as molding resin materials in practical use fields.

This invention relates to a resin composition containing a polyphenylene 
ether copolymer and provides a resin composition which is improved in heat 
resistance and long-term stability to oxidation at high temperatures and 
is excellent in mechanical properties and processibility. Polyphenylene 
ethers, typically poly(2,6-dimethyl-1,4-phenylene) ether, are known as 
thermoplastic resins excellent in heat resistance, mechanical and 
electrical properties. When used alone, however, they manifest 
insufficient processibility and poor stability to oxidation at high 
temperatures. These defects have confined the use of polyphenylene ethers 
as an engineering resin material and a general-purpose molding material 
within a narrow field. As is well known, in order to overcome partly the 
above difficulties, the polyphenylene ether is incorporated with various 
resins, particularly styrene resins, and the resulting resin compositions 
are now being in actual use as general-purpose molding materials with 
improved moldability (for example, U.S. Pat. No. 3,383,435 and Japanese 
Patent Publication No. 17,812/1968). However, although such a resin 
composition has improved moldability and is formable at a lower 
temperature, it unavoidably becomes inferior in heat resistance or 
mechanical properties, which is characteristic of a polyphenylene ether. 
In the field of molding materials prepared by modifying a polyphenylene 
ether, many attempts have heretofore been made to incorporate other resins 
into a polyphenylene ether, whereas very few attempts have been made to 
modify chemically the polyphenylene ether itself. The present inventors 
conducted studies on the copolymerizability of phenols in the oxidative 
polycondensation and, as a result, found that monomeric phenols in a 
specific combination show remarkably good copolymerizability and, 
moreover, the resulting polyphenylene ether copolymer exhibits entirely 
unexpectable performance characteristics. 
The present inventors performed further investigations on the resin 
compositions comprising the above polyphenylene ether copolymer 
incorporated with other resins and found that a resin composition 
comprising a certain polyphenylene ether copolymer and a polystyrene or a 
styrene copolymer incorporated therein can be extremely valuable for 
practical use, and can be free of the aforementioned general defects of 
polyphenylene ethers have been eliminated. These findings have led to the 
present invention. 
An object of this invention is to provide a novel resin composition having 
excellent performance characteristics comprising a polyphenylene ether 
copolymer and a styrene polymer with or without an additional rubber-like 
polymer. 
Other objects and advantages of this invention will become apparent from 
the following description. 
According to this invention there are provided a resin composition based on 
a polyphenylene ether comprising 99 to 1 part by weight of a polyphenylene 
ether copolymer derived from 99.5 to 85 mole-% of 2,6-dimethylphenol and 
0.5 to 15 mole-% of 3-methyl-6-tertbutylphenol and 1 to 99 parts by weight 
of a styrene-base polymer (the sum of both resins being 100 parts by 
weight); and a resin composition based on a polyphenylene ether comprising 
99 to 1 part by weight of a polyphenylene ether copolymer derived from 
99.5 to 85 mole-% of 2,6-dimethylphenol and 0.5 to 15 mole-% of 
3-methyl-6-tert-butylphenol and 1 to 99 parts by weight of a styrene 
polymer (the sum of both resins being 100 parts by weight), and 0.1 to 100 
parts by weight of a rubber-like polymer for 100 parts by weight of the 
sum of said two resins. 
The resin composition of this invention is much improved in various 
performance characteristics compared with known resin compositions 
comprising a polyphenylene ether and a styrene polymer, and there is 
provided a novel resin composition imparted with those performance 
characteristics which have never been achieved by the conventional resin 
compositions. The properties which characterize the present composition 
include heat resistance, and mechanical properties such as tensile 
strength, flexural strength, elongation, and impact resistance. Above all, 
a remarkable improvement in impact strength unaccompanied by deterioration 
of heat resistance greatly contributes to the expansion of the use of the 
composition in the field of molded articles. Because of the excellent 
moldability together with retained mechanical strengths and heat 
resistance, the resin composition of this invention is very useful as a 
practical molding material. 
The polyphenylene ether copolymer used in the present resin composition 
having excellent performance characteristics is that derived from 99.5 to 
85 mole-% of 2,6-dimethylphenol and 0.5 to 15 mole-% of 
3-methyl-6-tert-butylphenol (hereinafter referred to as 3M6B) and has a 
random and/or block structure. This copolymer may be prepared by passing 
oxygen or an oxygen-containing gas through said monomeric phenols in the 
presence of a catalyst to effect oxidative polycondensation. More 
particularly, it may be prepared by adding the whole of a predetermined 
amount of 3M6B to 2,6-dimethylphenol to be subjected to the known 
oxidative polycondensation, or by adding one of the monomers to the other 
monomer undergoing the oxidative polycondensation, or by allowing each 
monomer to polymerize independently to a predetermined polymerization 
degree and then combining both reaction mixtures to continue the oxidative 
polycondensation. 
The proportion of the structural unit derived from 3M6B in the 
polyphenylene ether copolymer for use in the present composition is 0.5 to 
15, preferably 1 to 10, most preferably 1.5 to 5 mole-%. In particular, a 
copolymer containing 2 to 3 mole-% of 3M6B has especially improved in 
mechanical characteristics. If the proportion of 3M6B is higher than 15 
mole-%, the polycondensation is likely not to proceed smoothly, the final 
molecular weight is not sufficiently high, and the heat resistance is 
deteriorated, while if the proportion is below 0.5 mole-%, characteristic 
features of the copolymer will not be sufficiently developed. 
On comparative examination of copolymers with other alkylphenols, no 
improvement in physical properties as remarkable as that obtained with 
3M6B was found. 
The other resin component used in the present composition mixed with the 
polyphenylene ether copolymer is a styrene polymer. The styrene polymers, 
as herein referred to, include polystyrenes and styrene-based copolymers 
which can be used each alone or in mixtures. The polystyrenes, as herein 
referred to, include homo- and co-polymers of styrene and derivatives 
thereof (hereinafter referred to briefly as vinyl aromatic monomers), 
typically styrene, .alpha.-methylstyrene, vinyltoluene and chlorostyrene. 
The styrene-based copolymer, as herein referred to, is a copolymer resin 
having a polymeric structure derived from a vinyl aromatic monomer and a 
monomer copolymerizable therewith. Representatives of such copolymer 
resins are impact-resistant polystyrenes, styrene-acrylonitrile copolymer, 
styrene-butadiene block copolymer, styrene-butadiene random copolymer, 
styrene-methyl methacrylate copolymer, styrene-butadiene-acrylonitrile 
copolymer, styrene-maleic anhydride copolymer, rubber-modified 
styrene-maleic anhydride copolymer, ethylene-styrene copolymer, and 
ethylene-propylene-butadiene-styrene copolymer. 
The vinyl aromatic monomers used in the styrene-based copolymers include 
styrene and derivatives thereof, as described above. The monomers 
copolymerizable with vinyl aromatic monomers include olefins, typically 
ethylene and propylene; acrylic monomers, typically acrylonitrile and 
methyl methacrylate; and conjugated diene monomers, typically butadiene, 
isoprene and chloroprene. 
The rubber-like polymers used in combination with the polyphenylene ether 
copolymer and a styrene-based copolymer to enhance the characteristics of 
the resin composition include for example polybutadiene, butadiene-styrene 
copolymer, ethylene-propylene copolymer, ethylene-propylene-conjugated 
diene copolymer, polyisoprene, polyisobutylene, polychloroprene, acrylic 
ester copolymer, and high-styrene rubber. 
The compounding ratio of the above compounds in the resin composition of 
this invention depends upon the type of each component such as the 
composition of polyphenylene ether copolymer, the type and properties of 
polystyrenes or styrene-based copolymers, and the intended use of the 
resin composition. In ordinary cases, suitable resin compositions contain 
99 to 1, preferably 95 to 5 parts by weight of the polyphenylene ether 
copolymer and 1 to 99, preferably 5 to 95 parts by weight of a 
styrene-based copolymer (making up a total of 100 parts by weight). 
The amount of rubber-like polymer, which is added if necessary, is 
desirably 0.1 to 100 parts by weight for 100 parts by weight of the resin 
compositions. 
In practicing the present invention, any known blending techniques can be 
used for blending a polyphenylene ether copolymer and a styrene polymer 
and further a rubber-like polymer. 
The resin components can be physically intermixed, for example, by 
dissolving the components each in a common solvent, mixing the resulting 
solutions, and co-precipitating the components by the addition of a 
precipitant, by blending the resin components together in a blender and 
extruding the resulting blend from an extruder or by blending the resin 
components by means of Bunbury's mixer or a kneader. The compounding can 
also be effected chemically, for example, by polymerizing, copolymerizing 
or graft-copolymerizing in the presence of the polyphenylene ether 
copolymer a vinyl aromatic monomer or a mixture of a vinyl aromatic 
monomer and a copolymerizable monomer, or by subjecting a mixture of 
2,6-dimethylphenol and 3M6B to oxidative co-condensation in the presence 
of a styrene-based copolymer and subjecting the resulting mixture to 
co-precipitation. Polymerization or graft-copolymerization can be carried 
out by any of the techniques of bulk-polymerization, suspension 
polymerization, solution polymerization and emulsion polymerization. A 
rubber-like polymer can be added to the polymerization system. 
The resin composition of this invention can be incorporated, if necessary, 
with various additives such as thermal stabilizers, pigments, fire 
retardants, plasticizers, lubricants, UV absorbers and colorants as well 
as fibrous reinforcements such as glass fiber, asbestos fiber, carbon 
fiber and alumina fiber. It is also possible to compound with other resin 
components unless the characteristics of the resin composition are injured 
.

The invention is illustrated below in detail with reference to Examples, 
but the invention is not limited thereto. 
REFERENCE EXAMPLE 1 
A solution containing 47.9 g of 2,6-dimethylphenol and 1.31 g of 3M6B 
dissolved in 196 g of xylene was placed in a 500-ml separable flask 
provided with an inlet tube for oxygen, a reflux condenser and a stirrer. 
A solution of 1.0 g of dehydrated manganese chloride in 84 g of methanol 
and a solution of 4.8 g of ethylenediamine, in 84 g of methanol were added 
into the flask. Oxygen was introduced with stirring into the reactant 
mixture at a flow rate of 100 ml/minute. After allowing the reaction to 
proceed at 30.degree. C. for about 3 hours, the oxygen stream was turned 
off. The resulting reaction mixture was admixed with 17 ml of concentrated 
hydrochloric acid and heated with stirring at 60.degree. C. for 1.5 hours. 
After cooling, the reaction mixture was poured into 1,000 g of methanol to 
precipitate the formed polymer which was then collected by filtration, 
washed with methanol and dried to obtain a polymer in a yield of 94%. The 
resulting polymer showed an intrinsic viscosity, [.eta.], of 0.55 dl/g, as 
determined in chloroform at 25.degree. C., and contained about 2 mole-% of 
the structural unit derived from 3M6B, as determined by NMR spectroscopy. 
EXAMPLE 1 
A mixture comprising 40 parts of the polyphenylene ether copolymer prepared 
in Reference Example 1, 53.6 parts of a commercial impact-resistant 
polystyrene (ESBRITE.RTM.500 A of Nippon Polystyrene Co.) and 6.4 parts of 
a commercial styrene-butadiene copolymer (Solprene 1204 of Showa Denko 
Co.) was milled by means of a Brabender Plastograph at 250.degree. C. for 
10 minutes and compression molded to obtain a molded specimen (A) having 
physical properties as shown in Table 1. 
For comparison, another molded specimen (B) was prepared in the same manner 
as above, except that 40 parts of poly(2,6-dimethyl-1,4-phenylene) ether 
having an intrinsic viscosity, [.eta.], of 0.55 dl/g were used in place of 
40 parts of the polyphenylene ether copolymer. The physical properties of 
the molded specimen (B) were as shown in Table 1. 
As is apparent from Table 1, the resin composition containing a 
polyphenylene ether copolymer derived from 2,6-dimethylphenol and 3M6B 
showed substantially identical heat distortion temperature and a 
remarkably improved impact resistance, as compared with the resin 
composition containing poly(2,6-dimethyl-1,4-phenylene) ether. 
TABLE 1 
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Type of molded 
Physical specimen 
property A B 
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Heat distortion temperature (.degree.C.), 
(load: 18.4 kg/cm.sup.2) 
111 113 
Tensile strength (kg/cm.sup.2) 
535 560 
Elongation (%) 45 30 
Flexural strength (kg/cm.sup.2) 
950 945 
Izod impact strength (kg . cm/cm) 
22 13 
(Notched; 1/3 inch) 
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EXAMPLE 2 
A mixture of 40 parts of a polyphenylene ether copolymer having an 
intrinsic viscosity, [.eta.], of 0.58 dl/g (in chloroform at 25.degree. 
C.), which had been derived from a monomer mixture of 97 mole-% of 
2,6-dimethylphenol and 3 mole-% of 3M6B, and 60 parts of a commercial 
impact-resistant polystyrene (ESBRITE.RTM. 500 A of Nippon Polystryene 
Co.) was milled in a Brabender Plastograph at 250.degree. C. for 10 
minutes and compression molded. The molded specimen showed an Izod impact 
strength of 9 kg.cm/cm (notched; 1/3 inch). 
Another compression molded specimen was prepared by using a 
poly(2,6-dimethyl-1,4-phenylene) ether having an intrinsic viscosity 
[.eta.], of 0.60 dl/g and milling and molding in the same manner as above. 
Upon testing, the Izod impact strength was found to be as low as 4 
kg.cm/cm. 
EXAMPLES 3 to 8 and COMATIVE EXAMPLES 1 to 5 
A mixture comprising 40 parts of a polyphenylene ether copolymer derived 
from 2,6-dimethylphenol and an another phenol, 53.6 parts of a commercial 
impact-resistant polystyrene (ESBRITE.RTM. 500 AS of Nippon Polystyrene 
Co.) and 6.4 parts of a styrene-butadiene copolymer (Solprene.RTM. 1204 of 
Showa Denko Co.) was milled and molded in the same manner as in Example 1. 
The molded specimen was tested for heat distortion temperature and impact 
strength. The results obtained were as shown in Table 2. 
TABLE 2 
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Izod impact 
Heat distor- 
strength 
tion temp. 
(kg . cm/cm) 
Phenolic [.eta.] 
(.degree.C.) (load: 
(notched; 
No. co-monomer 
Mole-% 
dl/g 
18.4 kg/cm.sup.2) 
1/3 in.) 
__________________________________________________________________________ 
Comparative Example 1 
-- -- 0.50 
113 13 
Comparative Example 2 
2,5-Xylenol 
2 0.84 
110 14 
Comparative Example 3 
Thymol 2 0.60 
110 13 
Comparative Example 4 
Thymol 5 0.50 
104 14 
Example 3 3M6B 1 0.80 
112 15 
Example 4 3M6B 2 0.60 
111 24 
Example 5 3M6B 3 0.52 
111 22 
Example 6 3M6B 5 0.50 
111 17 
Example 7 3M6B 10 0.65 
107 15 
Example 8 3M6B 15 0.55 
104 13 
Comparative Example 5 
3M6B 20 0.31 
96 6 
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EXAMPLE 9 
A mixture comprising 50 parts of a polyphenylene ether copolymer having an 
intrinsic viscosity of 0.5 dl/g (in chloroform at 25.degree. C.), which 
had been derived from a mixture of 2,6-dimethylphenol and 3M6B in a molar 
ratio of 95:5, 35 parts of a commercial impact-resistant polystyrene 
(ESBRITE.RTM. 500 A of Nippon Polystyrene Co.), 15 parts of a mixed resin 
of styrene-butadiene copolymer and polystyrene in a weight ratio of 
1.1:1.0, 5 parts of triphenyl phosphate, 7 parts of titanium oxide and 1 
part of a thermal stabilizer was thoroughly milled in a Henschell mixer 
and pelletized by means of a twinscrew extruder. The pellets were easily 
molded at an injection pressure of 1,100 kg/cm.sup.2 and a maximum 
injection temperature of 260.degree. C. The characteristics of this resin 
composition were as follows: heat distortion temperature, 120.degree. C.; 
tensile strength, 560 kg/cm.sup.2 ; elongation, 40%; flexural strength, 
890 kg/cm.sup.2 ; Izod impact strength (notched; 1/3 inch), 17 kg.cm/cm. 
EXAMPLE 10 
A solution containing a total of 10% by weight of 2,6-dimethylphenol and 
3M6B was prepared by dissolving both compounds in a toluene solution 
containing 7% by weight of an impact-resistant polystyrene. An oxygen 
stream was introduced into the solution in the presence of a 
manganese-amine complex catalyst to effect oxidative polycondensation of 
both phenols. There was thus obtained a resin composition comprising a 
polyphenylene ether copolymer derived from 2,6-dimethylphenol and 3M6B in 
a molar ratio of 97:3 and an impact-resistant polystyrene. The ratio 
between the polyphenylene ether copolymer and the impact-resistant 
polystyrene in the resin composition was 60:40 by weight. To 100 parts of 
the said resin composition, were added 1 part of a thermal stabilizer, 5 
parts of triphenyl phosphate, and 7 parts of titanium oxide. The mixture 
was thoroughly mixed in a Henschel mixer and pelletized by extruding from 
a twin-screw extruder. The physical properties of the molded specimen 
prepared from the resin composition were as follows: heat distortion 
temperature, 130.degree. ; Izod impact strength, 15 kg.cm/cm.