Polyphenylene ether resin composition

A polyphenylene ether resin composition comprising PA0 (A) a polyphenylene ether resin modified with a 1,2-substituted olefin compound having an acid anhydride group, the polyphenylene either resin before modification having structural units represented by the following ##STR1## wherein R.sup.1 represents a lower alkyl group having 1 to 3 carbon atoms, and R.sup.2 and R.sup.3, independently from each other, represent a hydrogen atom or a lower alkyl group having 1 to 3 carbon atoms, in the main chain, and PA0 (B) a polyamide resin having recurring units represented by the following formula (II) EQU --R.sup.4 --NHCO--R.sup.5 --CONH-- (II) PA0 wherein R.sup.4 represents a xylylene group, and R.sup.5 represents a linear alkylene group having 4 to 10 carbon atoms.

This invention relates to a polyphenylene ether resin composition. More 
specifically, it relates to a polyphenylene ether resin composition 
comprising a modified polyphenylene ether resin and a polyamide and as 
required, a rubber-modified styrene polymer and/or glass fibers, and 
having excellent moisture absorption characteristics, moldability, 
mechanical properties and impact strength. 
Polyphenylene ether resins have excellent thermal, mechanical and 
electrical properties, but have the defect of being inferior in 
moldability because the melt processing temperatures for them is high and 
their flowability is low. They have strong resistance to inorganic 
chemicals such as acids and alkalies, but in contact with certain kinds of 
organic solvents, these resins are dissolved or swollen. It has been 
strongly desired therefore to improve the solvent resistance and oil 
resistance of the polyphenylene ether resins. 
As an attempt to improve both moldability and oil resistance, there have 
been proposed a method comprising incorporating not more than 20% of a 
polyamide in a polyphenylene ether resin (Japanese Patent Publication No. 
997/1970) and a method comprising incorporating 30 to 95% of a polyamide 
in a polyphenylene ether resin (Japanese Patent Publication No. 
41663/1984). The addition of a small amount of polyamide leads to some 
improvement in moldability, but can never sufficiently improve oil 
resistance. On the other hand, a large amount of polyamide improves 
solvent resistance, but gives a brittle material without toughness. This 
is believed to be due to the inherently poor compatibility between a 
polyphenylene ether resin and a polyamide resin. 
Various methods have previously been known for enhancing compatibility 
between a polyphenylene ether resin (to be referred to as PPE) and a 
polyamide resin. They include, for example a method in which a compound 
having a carbon-carbon double bond and a functional group such as a 
carboxylic acid group, an acid anhydride group, an acid amide group or an 
imide group in the molecule, such as maleic acid or maleimide, is 
incorporated as a third component in a composition comprising PPE and a 
polyamide (Japanese Laid-Open Patent Publication No. 26913/1981); a method 
in which a 1,2-substituted olefin compound having a carboxyl group or an 
acid anhydride structure is reacted with PPE in the presence of a radical 
initiator (Japanese Patent Publication No. 66452/1984); a method in which 
a copolymer of a styrene compound and an alpha,beta-unsaturated 
dicarboxylic acid is incorporated in a composition comprising PPE and a 
polyamide resin (Japanese Patent Publication No. 33614/1984); and a method 
in which a melt-mixed product of a mixture of PPE and an ethylenically 
unsaturated carboxyl compound is blended with a polyamide (Japanese 
Laid-Open Patent Publication No. 138553/1987). The addition of maleic 
anhydride or maleimide as a third component to the composition cannot 
bring about a sufficient improvement in compatibility. Molding of the 
resulting resin compositions at high temperatures and high speeds as in 
injection molding gives molded articles which develop delamination or poor 
appearance, and materials having sufficient toughness are difficult to 
obtain. Incorporation of a copolymer of maleic anhydride and styrene 
results in a reduction in thermal resistance. On the other hand, a 
polyamide resin obtained from a xylylenediamine and an alpha,omega-linear 
aliphatic dicarboxylic acid has excellent thermal properties, mechanical 
properties upon moisture absorption, and solvent resistance, but does not 
have sufficient impact strength. 
It is an object of this invention to provide a polyphenylene ether resin 
composition having a novel chemical composition. 
Another object of this invention is to provide a polyphenylene ether resin 
composition comprising a modified polyphenylene ether resin and a 
polyamide resin having xylylenediamine as a diamine component. 
Still another object of this invention is to provide a polyphenylene ether 
resin composition having excellent moisture absorption characteristics, 
moldability, mechanical properties and impact strength. 
Yet another object of this invention is to provide a polyphenylene ether 
resin composition which changes little in properties during water 
absorption and in dimension and requires only a short cooling time during 
molding. 
Further objects of this invention along with its advantages will become 
apparent from the following description. 
According to this invention, these objects and advantages of the invention 
are achieved by a polyphenylene ether resin composition comprising 
(A) a polyphenylene ether resin modified with a 1,2-substituted olefin 
compound having an acid anhydride group, the polyphenylene ether resin 
before modification having structural units represented by the following 
formula (I) 
##STR2## 
wherein R.sup.1 represents a lower alkyl group having 1 to 3 carbon atoms, 
and R.sup.2 and R.sup.3, independently from each other, represent a 
hydrogen atom or a lower alkyl group having 1 to 3 carbon atoms, in the 
main chain, and 
(B) a polyamide resin having recurring units represented by the following 
formula (II) 
EQU --R.sup.4 --NHCO--R.sup.5 --CONH-- (II) 
wherein R.sup.4 represents a xylylene group, and R.sup.5 represents a 
linear alkylene group having 4 to 10 carbon atoms. 
The modified polyphenylene ether resin (A) constituting the composition of 
the invention is a modification product of polyphenylene ether having 
structural units of the following formula (I) 
##STR3## 
wherein R.sup.1 represents an alkyl group having 1 to 3 carbon atoms, and 
R.sup.2 and R.sup.3, independently from each other, represent a hydrogen 
atom or an alkyl group having 1 to 3 carbon atoms, in the main chain. 
The lower alkyl group of 1 to 3 carbon atoms represented by R.sup.1, 
R.sup.2 and R.sup.3 in formula (I) may be linear or branched, and may, for 
example, be methyl, ethyl, n-propyl, and isopropyl. 
The polyphenylene ether resin of formula (I) may be a homopolymer, a 
copolymer or a graft copolymer. Specific examples include 
poly(2,6-dimethyl-1,4-phenylene)ether, 
poly(2,6-diethyl-1,4-phenylene)ether, 
poly(2,6-dipropyl-1,4-phenylene)ether, 
poly(2-methyl-6-ethyl-1,4-phenylene)ether, and 
poly(2-methyl-6-propyl-1,4-phenylene)ether. 
Poly(2,6-dimethyl-1,4-phenylene)ether and 
2,6-dimethylphenol/2,3,6-trimethylphenol copolymer, and grafted copolymers 
obtained by grafting styrene thereto are especially preferred as the 
polyphenylene ether resin used in this invention. 
The modified polyphenylene ether resin (to be referred to sometimes as the 
modified PPE) used in this invention is obtained by modifying the above 
unmodified polyphenylene ether resin with a 1,2-substituted olefin 
compound having an acid anhydride group (--CO--O--CO--). 
Modification of PPE with the 1,2-substituted olefin compound can be 
achieved by melt-kneading the two compounds under heat in the absence of 
catalyst. Melt-kneading may be carried out by using conventional machines 
such as a kneader, a Banbury mixer and an extruder. From the viewpoint of 
operability, the extruder is preferably used. As required, the 
modification of PPE with the 1,2-substituted olefin compound may be 
carried out in the presence of a radical initiator such as benzoyl 
peroxide, dicumyl peroxide or cumene hydroperoxide. 
Examples of the 1,2-substituted olefin compound having an acid anhydride 
group are maleic anhydride, itaconic anhydride, and citraconic anhydride. 
The maleic anhydride is especially preferred. 
The amount of the acid anhydride required for modifying PPE is 0.01 to 10 
parts by weight, preferably 0.1 to 3 parts by weight, especially 
preferably 0.1 to 1 parts by weight, per 100 parts by weight of PPE. If 
the acid anhydride is used in smaller amounts, the effect of improving 
compatibility between PPE and the polyamide resin is small, and a tough 
composition is difficult to obtain. If it is used in larger amounts, 
troubles such as thermal decomposition of the excess of the acid anhydride 
occur, and undesirable phenomena such as reduced thermal resistance and 
poor appearance occur in the resulting resin composition. 
The polyamide resin (B) constituting the resin composition of this 
invention is composed of structural units represented by the following 
formula (II) 
EQU --R.sup.4 --NHCO--R.sup.5 --CONH-- (II) 
wherein R.sup.4 represents a xylylene group, and R.sup.5 represents a 
linear alkylene group having 4 to 10 carbon atoms. 
Preferably, the xylylene group for R.sup.4 in formula (II) is, for example, 
a m-xylylene or p-xylylene group. 
The linear alkylene group having 4 to 10 carbon atoms for R.sup.5 may be a 
polymethylene group having 4 to 10 carbon atoms, such as a tetramethylene, 
pentamethylene, hexamethylene, heptamethylene, octamethylene, 
nonamethylene or decamethylene group. 
The polyamide resin (B) may be obtained by polycondensing a xylylenediamine 
and an alpha,omega-linear alkylene dibasic acid in a customary manner. 
The xylylenediamine may, for example, be m-xylylenediamine, 
p-xylylenediamine or a mixture thereof, particularly a mixture of at least 
60 mole % of m-xylylenediamine and not more than 40 mole % of 
p-xylylenediamine. 
Examples of the alpha,omega-linear alkylene dibasic acid are adipic acid, 
sebacic acid, suberic acid, undecanoic acid and dodecanoic acid. Adipic 
acid and sebasic acid are preferred. 
The blending weight ratio of the modified PPE (A) to the polyamide resin 
(B) may be varied over a wide range, preferably from 0.1 to 5, especially 
preferably from 0.3 to 3. If this ratio is outside the range specified, 
there is an increasing tendency toward deterioration in water resistance, 
dimensional stability and oil resistance which are the characteristics of 
the modified PPE (A)/polyamide resin (B) composition. 
The resin composition of this invention may, as required, further contain 
polyhexamethylene adipamide (nylon 66). The resin composition of this 
invention containing nylon 66 is particularly conducive to shortening of 
the molding cycle. The proportion of nylon 66 to be added may effectively 
range over a wide range from the standpoint of shortening the molding 
cycle. But when the physical properties of the resulting molded article 
are considered also, it is 0.03 to 6 parts, preferably 0.03 to 4 parts, by 
weight per part by weight of the polyamide resin (B). If it is less than 
the specified lower limit, there is no appreciable effect on the 
shortening of the molding cycle. If, on the other hand, it exceeds the 
specified upper limit, the resulting composition greatly decrease in 
strength and changes in dimension upon water absorption and troubles in 
practical applications occur. 
The proportion of the modified PPE (A) to be blended is preferably 0.1 to 5 
times, especially preferably 0.3 to 3 times, the total weight of the 
polyamide resin (B) and nylon 66. If the proportion of the modified PPE 
(A) is below the specified lower limit, the effect of improving thermal 
resistance and water absorption characteristics is small. If it exceeds 
the specified upper limit, the flowability of the molten resin is 
undesirably reduced during molding. 
If required, the resin composition of this invention may further comprise a 
rubber-modified styrene resin. The resin composition of this invention 
containing the rubber-modified styrene resin has especially improved 
toughness. 
The rubber-modified styrene resin used in this invention is a 
rubber-modified styrene polymer obtained by copolymerizing a conjugated 
diolefin compound and styrene with or without at least one monovinyl 
compound copolymerizable with the conjugated diolefin compound. 
Examples of the rubber-modified styrene resin used in this invention are 
polybutadiene-styrene copolymer, polybutadiene-acrylonitrile-styrene 
copolymer and polybutadiene-methyl methacrylate-styrene copolymer. 
The amount of the rubber-modified styrene resin is 2 to 100 parts by 
weight, preferably 5 to 60 parts by weight, per 100 parts by weight of the 
polyamide resin (B) and nylon 66 combined. If it is smaller than the 
specified lower limit, there is no appreciable effect of improving 
toughness. If, on the other than, it exceeds the specified upper limit, 
mechanical properties such as strength and modulus are reduced and the 
resulting composition has a low heat distortion temperature. Consequently, 
troubles occur in practical applications. 
The resin composition of this invention comprising the polyamide resin (B), 
nylon 66 and the rubber-modified styrene resin may further contain a 
fibrous reinforcing material such as glass fibers and carbon fibers. 
Furthermore, as required, it may contain various additives for polymeric 
materials, such as stabilizers, pigments, dyes, mold releasing agents, 
lubricants and fillers. 
According to this invention, there is also provided a resin composition 
comprising the modified PPE (A), the polyamide resin (B), nylon 66 and 
glass fibers. 
The suitable amount of the glass fibers is 10 to 150 parts by weight per 
100 parts by weight of the modified PPE (A), the polyamide resin (B) and 
nylon 66 combined. If the amount of the glass fibers is smaller than the 
specified lower limit, no sufficient effect is obtained of improving 
mechanical properties and heat distortion temperature. If it is larger 
than the specified upper limit, the composition in the molten state has 
reduced flowability, and operational troubles occur during injection 
molding, and the surface condition of the resin tends to be worse. 
A fibrous reinforcing material such as carbon fibers may be incorporated in 
this composition. Furthermore, as required, it may further comprise 
various additives generally used for polymeric materials, such as 
stabilizers, pigments, dyes, mold releasing agents, lubricants, and 
fillers. 
This resin composition may be produced by melt-kneading the ingredients by 
using an ordinary vent-type extruder or the like. The melt-kneading 
temperature is preferably 5.degree. to 50.degree. C. higher than the 
melting point of the resin composition.

The following Examples and Comparative Examples illustrate the present 
invention more specifically. All parts in these examples are by weight. 
EXAMPLE 1 AND COMATIVE EXAMPLE 1 
Maleic anhydride (25 g) was added to 5 kg of PPE having an inherent 
viscosity, measured in chloroform at 25.degree. C., of 0.45 dl/g, and they 
were mixed for 3 minutes by a supermixer. Then, the mixture was 
melt-kneaded under heat in a twin-screw extruder to give maleic 
anhydride-modified PPE. 
Fifty parts of the resulting maleic anhydride-modified PPE and 50 parts of 
m-xylylene adipamide resin obtained by polycondensation of 
m-xylylenediamine and adipic acid and having a melting point, measured by 
DSC, of 230.degree. C. (produced by Mitsubishi Gas Chemical Company, Inc.; 
to be referred to as nylon MXD6) were dry-blended by a tumbler, and then 
melt-mixed in an extruder to give a resin composition. 
The resin composition was molded by a molding machine to form various test 
pieces. The properties of the test pieces measured are shown in Table 1. 
Tensile strength was measured in accordance with ASTM D638, and flexural 
modulus, in accordance with ASTM D790. 
For comparison, a resin composition was prepared in the same way as above 
except that nylon 66 was used instead of the nylon MXD6. The results are 
also shown in Table 1 (Comparative Example 1). 
Table 1 shows that the resin composition of Example 1 show little 
deterioration in mechanical properties after water absorption. 
TABLE 1 
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Comparative 
Test item Example 1 Example 1 
______________________________________ 
Heat distortion temperature 
144 170 
(.degree. C.) 
Tensile strength (kg/cm.sup.2) 
After drying (*1) 873 760 
After moisture 803 650 
absorption (*2) 
Flexural modulus (kg/cm.sup.2) 
After drying (*1) 32,400 26,100 
After moisture 30,100 23,300 
absorption (*2) 
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(*1): After drying 
After molding, the molded article was left to stand for 24 hours at 
23.degree. C. and 50% RH, and then subjected to measurement. 
(*2): After moisture absorption 
The molded article was immersed in water at 23.degree. C., then taken out 
and wiped free of adhering moisture, and thereafter subjected to 
measurement in an atmosphere at 23.degree. C. and 50% RH. 
EXAMPLE 2 AND COMATIVE EXAMPLE 2 
Maleic anhydride (25 g) was added to 5 kg of PPE (Iupiace CPX 100, a 
tradename for a product of Mitsubishi Gas Chemical Co., Ltd.), and they 
were mixed for 30 minutes by a supermixer. The mixture was melt-kneaded at 
300.degree. C. in a twin-screw extruder to give maleic anhydride-modified 
PPE. 
The resulting maleic anhydride-modified PPE (42.5 parts), 42.5 parts of 
nylon MXD6 having a number average molecular weight of 1600, 5 parts of 
nylon 66 having a number average molecular weight of 18000 and 10 parts of 
styrene/butadiene copolymer having a number average molecular weight of 
60000 and a combined styrene content of 43% by weight (Stereon 840A, a 
tradename for a product of Firestone Company) were mixed in a mixer and 
melt-kneaded in a single-screw extruder at a cylinder temperature of 
285.degree. C. and extruded into a strand. The strand was cooled with ice, 
cut into pellets and dried to give a resin composition. 
The pellets were molded by an injection-molding machine at a mold 
temperature of 130.degree. C. and a cylinder temperature of 285.degree. C. 
to prepare various test pieces. The properties of the test pieces were 
measured, and the results are shown in Table 2. 
For comparison, a resin composition was prepared from 47.5 parts of nylon 
MXD6, 42.5 parts of the modified PPE and 10 parts of styrene-butadiene 
copolymer (the same as those used in Example 2 above) was prepared, and 
its properties were measured as above. The results are also shown in Table 
2 (Comparative Example 2). 
The results demonstrate that the addition of nylon 66 greatly shortened the 
time required for cooling during molding. 
TABLE 2 
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Comparative 
Proportions and test items 
Example 2 Example 2 
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Proportions (parts) 
Nylon MXD6 42.5 47.5 
Nylon 66 5 0 
Modified PPE 42.5 42.5 
Styrene/butadiene 10 10 
copolymer 
Properties 
Tensile strength 
(kg/cm.sup.2) 
After drying (*1) 641 650 
After moisture 587 582 
absorption (*2) 
Flexural modulus 
(10.sup.3 kg/cm.sup.2) 
After drying (*1) 26 30 
After moisture 24 26 
absorption (*2) 
Izod impact strength 
6.7 5.9 
(notched) (*3) (kg-cm/cm) 
Moldability 
Time required for 16 30 
cooling (*4) (sec) 
Molding pressure 420 420 
(kg/cm.sup.2) 
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(*1) and (*2): Same as the footnote to Table 1. 
(*3): Measured after drying (*1). 
(*4): In injection molding at a molding temperature of 130.degree. C. by 
an injection molding machine, the time required for cooling until the 
surface hardness of the molded article immediately after mold opening 
reaches a Barcol hardness of 20. 
EXAMPLES 3-4 
Maleic acid (50 g) was added to 5 kg of PPE (Iupiace CPX 100, a tradename 
for a product of Mitsubishi Gas Chemical Company, Inc.), and they were 
mixed by a supermixer for 3 minutes. The mixture was melt-kneaded at 
300.degree. C. in a twin-screw extruder to give maleic anhydride-modified 
PPE. 
The resulting maleic anhydride-modified PPE (35 parts), 30 parts of nylon 
MXD6 having a number average molecular weight of 16000, 5 parts of nylon 
66 having a number average molecular weight of 18000 and 30 parts of 
chopped strands of glass fibers having a length of 3 mm were blended and 
melt-kneaded in a single-screw extruder at a cylinder temperature of 
285.degree. C. and extruded into a strand. The strand was cooled, cut into 
pellets, and dried to form a molding resin composition. 
The pellets were molded by an injection-molding machine at a mold 
temperature of 130.degree. C. and a cylinder temperature of 285.degree. C. 
to prepare various test pieces. 
The flexural strength, flexural modulus and coolant resistance within a 
temperature range of 20.degree. to 140.degree. C. of the test pieces were 
measured. The results are shown in Table 3. 
The methods of measurements were as follows: 
(1) Flexural strength: ASTM D790 
(2) Flexural modulus: ASTM D790 
(3) Coolant resistance: 
Retention: The test piece was immersed for 7 days at 120.degree. C. in a 
coolant liquid (Yamaha Long Life Coolant 1 PC, made by Yamaha Engine Co., 
Ltd.). The retention is the percentage of the tensile strength of the test 
piece measured after immersion based on its tensile strength. (The tensile 
strength was measured in accordance with ASTM D638.) 
Weight increase: The percent increase in weight when the above retention is 
measured. 
TABLE 3 
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Proportions and test items 
Example 3 Example 4 
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Proportions (parts) 
Nylon MXD6 20 30 
Nylon 66 10 5 
Modified PPE 20 15 
Glass fibers 50 50 
Properties 
Flexural strength (kg/cm.sup.2) 
Temperature (.degree.C.) 
20 3010 3320 
80 2250 2400 
100 1930 2000 
120 1610 1680 
140 1460 1510 
Flexural modulus (10.sup.3 kg/cm.sup.2) 
Temperature (.degree.C.) 
20 142 145 
80 107 105 
100 92 82 
120 85 73 
140 74 70 
Coolant resistance 
Retention of 51.6 55.1 
tensile strength 
(%) 
Weight increase 3.8 4.3 
(%) 
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EXAMPLES 5-6 AND COMATIVE EXAMPLES 3-5 
In each run, a resin composition was prepared and molded into test pieces 
in the same way as in Example 3 except that the amounts of the ingredients 
were changed as indicated in Table 4. 
The tensile strengths and flexural moduli of the test pieces were measured 
as in Example 1, and the moldabilities of the test pieces were determined 
as in Example 4. 
For comparison, the above procedure was repeated except that nylon MXD6 or 
nylon 66 was not used in preparing the resin composition. 
The results are shown in Table 4. 
TABLE 4 
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Comparative 
Proportions and 
Example Example 
test items 5 6 3 4 5 
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Proportions (parts) 
Nylon MXD6 22 32 0 10 40 
Nylon 66 6 4 30 0 0 
Modified PPE 22 14 20 40 10 
Glass fibers 50 50 50 50 50 
Properties 
Tensile strength 
(kg/cm.sup.2) 
After drying (*1) 
2380 2510 2130 1990 2610 
After moisture 
2365 2388 1990 1980 2540 
absorption (*2) 
Flexural modulus 
(10.sup.3 kg/cm.sup.2) 
After drying (*1) 
124 152 105 144 164 
After moisture 
121 148 94 143 160 
absorption (*2) 
Moldability 
Time required for 
15 16 13 13 39 
cooling (*3) (sec) 
Molding pressure 
700 680 800 1330 770 
(kg/cm.sup.2) 
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(*1) and (*2): Same as the footnote to Table 1. 
(*3): Same as the footnote (*4) to Table 2. 
From the results given in Table 4, it is seen that the molding resin 
compositions comprising the modified PPE and glass fibers and the mixed 
polyamide of nylon MXD6 and nylon 66 have excellent improved strength, 
rigidity, water resistance and moldability.