Thermoplastic resin composition

0001This invention relates to a novel thermoplastic resin composition suitable for shaped articles, sheet or film by injection molding or extrusion molding. More particularly, it relates to a novel thermoplastic resin composition superior in heat resistance, mechanical properties and processability, which contains a mutual compatibilizer in a resin composition containing a dispersing phase of polyphenylene ether and a polyamide matrix phase.

0002Polyphenylene ether is a thermoplastic resin superior in various mechanical properties, heat resistance, electrical properties, chemical resistance, hot water resistance, flame resistance and dimension stability, but inferior In processability due to a high melt viscosity and a relatively inferior impact resistance.

0003A composition comprising polyphenylene ether and polystyrene is proposed in order to lessen the melt viscosity of polyphenylene ether and to improve the processability thereof, leaving various other good properties of polyphenylene ether unchanged. However, such inherent good properties of polyphenylene as heat resistance, flame resistance and chemical resistance are somewhat damaged when enough polystyrene is added to provide processability practically No sufficient improvement is seen in impact resistance, either, even after polystyrnee is added.

0004On the other hand. crystalline thermoplastic resins are usually superior in heat resistance, stiffness. strength and oil resistance, but are inferior in impact resistance in many cases. In order to improve the impact strength of the resins, rubber components are blended or copolymerized therewith to obtain a large reduction in heat resistance and surface hardness. Further, crystalline thermoplastic resins when molten decrease in viscosity and can readily be molded. However, when they are molded at temperatures even slightly lower than their crystallizing solidification temperature, they are rapidly hardend and thus only a narrow range of molding conditions can be used. Moreover, they exhibit a change of properties and size during practical use. Further, most heat resistant crystalline thermoplastic resins are highly susceptibile to water and not only exhibit a change of properties and dimension, but are inferior in appearance.

0005New applications would be expected for a resin composition prepared by blending polyphenylene ether and a crystalline thermoplastic resin, so as to maintain the favorite properties of both components and to achieve improved processability and impact strength However. polyphenylene ether and crystalline thermoplastic resins are greatly different in melt viscosity from each other and they are very poor in compatibility. Simple blending of them encounters the following difficulties: <ul id="ul0001" list-style="none" compact="compact"><li>1. hardness in stable take-up of strands extruded and greatly lower processability in molding, because their melt viscosity difference is very large; and</li><li>2. no improvement in the mechanical properties of shaped articles, particularly impact resistance, but rather lower than expected on the basis of their respective values.</li></ul>

0006One approach to solve these problems is addition of additives having reactivity or compatibility to a system of polyphenylene ether and polyamide as disclosed in Japanese Patent Publication (Kokoku) No. 60-11966 and Japanese Patent Publication (Kokai) Nos. 56-47432, 57-10642 and 60-58463. Especially, the methods disclosed in Japanese Patent Publication (Kokoku) No. 60-11966 and Japanese Patent Publication (Kokai) No. 56-47432 afford good effect, but impact strength is still not enough.

0007Furthermore, Japanese Patent Publication (Kokai) Nos. 56-49753, 57-10642, 57-165448 and 59-66452 disclose the use of additives reactive with modified polystyrene, polyphenylene ether or rubber. However, the disperse phase is not clear and even when polyphenylene ether is the disperse phase, no mention is made of particle size. Such a composition is out of balance between impact resistance and heat resistance and besides the improvement of impact resistance is still not sufficient.

0008After a study of resin compositions of polyphenylene ether and crystalline thermoplastic resins. we have found that a resin composition having a good balance between heat resistance and impact resistance, markedly improved impact resistance and superior processability is obtained by adding a mutual compatibilizer (C) to a composition of a polyphenylene ether disperse phase (A) and a polyamide matrix phase (B) with a specific particle size of said disperse phase

0009Accordingly, the invention provides a thermoplastic resin composition which comprises a composition comprising (A) a dispersed phase of polyphenylene ether having a reduced viscosity of from 0.45 to 0.55 measured in chloroform solution at 25°C and being obtainable by oxidation polymerization of at least one phenol compound represented by the formula <chemistry id="chem0001" num="0001"><img file="EP0262901B2_D0001.tif" /></chemistry> wherein R₁, R₂, R₃, R₄ and R₅ each represents a hydrogen atom, a halogen atom or a substituted or unsubstituted hydrocarbon residue and at least one of them is a hydrogen atom. (B) a polyamide matrix phase and (C) a mutual compatibilizer compatible with (A) and or (B) which is at least one compound containing in its molecule, at least one of carboxyl group, acid anhydride group, acid amide group, imide group, carboxylate group, amino group, isocyanate group, oxazoline ring-containing group and hydroxyl group, with the proviso that neither a block copolymer comprising units of a vinyl aromatic compound and a diene nor an epoxy compound is present, the average particle diameter in said dispersing phase being 0.01 - 10 µm, the amount of (A) being at least 1 % by weight, that of (B) being 35 - 98.9% by weight and that of (C) being 0.1 - 50% by weight, the percentages being based on the combined weight of (A), (B) and (C).

0010The polyphenylene ether (A) is obtainable, for example, by oxidation polymerization of one or more phenol compounds having the above formula with molecular oxygen or a gas containing the same in the presence of an oxidation coupling catalyst.

0011Examples of R₁-R₅ are a hydrogen atom, a chlorine atom. a bromine atom, a fluorine atom, an iodine atom, a methyl group, an ethyl group, an n- or iso-propyl group, a pri.-, sec.-or tert.-butyl group, a chloroethyl group, a hydroxyethyl group, a phenylethyl group, a benzyl group, a hydroxymethyl group, a carboxyethyl group, a methoxycarbonylethyl group, a cyanoethyl group, a phenyl group, a chlorophenyl group, a methylphenyl group, a dimethylphenyl group, an ethylphenyl group or an allyl group.

0012Examples of phenol compounds are phenol, o-. m-or p-cresol, 2.6-, 2.5-, 2,4- or 3,5-dimethylphenol, 2-methyl-6-phenylphenol, 2,6-diphenylphenol, 2,6-diethylphenol, 2-methyl-6-ethylphenol, 2,3,5-, 2,3,6- or 2,4,6-trimethylphenol, 3-methyl-6-t. butylphenol, thymol and 2-methyl-6-allylphenol. Alternatively, a copolymer of any of the phenol compounds listed above and another phenol compound, for example, a polyhydroxy aromatic compound. may be employed. The polyhydroxy aromatic compound is, for example, bisphenol A, tetrabromobisphenol A, resorcin, hydroquinone or novolack resin.

0013Preferably polymers are a homopolymer of 2,6-dimethylphenol or 2,6-diphenylphenol and copolymers of a large amount of 2.6-xylenol and a small amount of 3-methyl-6-t-butylphenol or of 2,3,6-trimethylphenol.

0014Any oxydation coupling catalyst may be employed for oxydation polymerization of the phenol compound, as long as it has polymerization ability. Examples are cuprous compound/tert. amine such as cuprous chloride/triethylamine and cuprous chloride/pyridine; cupric compound/amide/alkali metal hydroxide such as cupric chloride/pyridine potassium hydroxide; manganese salt/primary amine such as manganese chloride/ethanolamine and manganese acetate/ethylenediamine; manganese salt/alcolate or phenolate such as manganese chloride/sodium methylate and manganese chloride/sodium phenolate; and cobalt salt/tert amine.

0015The polymerisation temperature for preparing polyphenylene ether is 40°C or higher (high temperature polymerization) or lower (low temperature polymerization) Either temperature may be used, although polymers produced thereby have different properties.

0016Polyphenylene ether (A) may be grafted with a styrenic polymer or another polymer. For instance, a grafted polymer is obtained by graft-polymerizing styrene monomer and/or other-comonomer in the presence of polyphenylene ether and organic peroxide (Japanese Patent Publications (Kokoku) 47-47862. 48-12197, 49-5623, 52-38596 and 52-30991) or by melt-kneading polyphenylene ether and polystyrene in the presence of a radical initiator (Japanese Patent Publication (Kokai) 52-142799).

0017The reduced viscosity of polyphenylene ether (A) measured in 0.5 g/dl chloroform solution at 25 °C is 0.45 - 0.55. When the reduced viscosity is less than 0.45 or more than 0.60, the impact strength of the composition decreases.

0018As the polyamide, there may be used one obtainable by polycondensation of lactams of three or more membered rings, polymerizable ω-amino acids, dibasic acids with diamines, etc. As typical examples thereof, mention may be made of polymers of ε-caprolactam. aminocaproic acid, enantholactam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, etc., polymers obtained by polycondensation of diamines such as hexamethylenediamine, nonamethylenediamine undecamethylenediamine, dodecamethylenediamine, m-xylylenediamine, etc with dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, sebacic acid, dibasic dodecanoic acid, glutaric acid, etc., or copolymers thereof.

0019Typical examples of said polyamides are aliphatic polyamides such as polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 11, polyamide 12, polyamide 6, 12, etc. and aromatic polyamides such as polyhexamethylenediamine terephthalamide, polyhexamethylenediamine isophthalamide, xylene group-containing polyamides, etc. These may also be used as mixtures of copolymers of two or more of them.

0020The mutual compatibilizer (C) is compatible with the polyphenylene ether dispersed phase (A) and/or the polyamide matrix phase (B) and has a function to stabilize each of said phases and does not cause poor appearance or deterioration of properties due to unstable phases during actual use.

0021The mutual compatibilizer per se has affinity with or is able to react with (A) and/or (B) and has impact absorbing capacity.

0022As the mutual compatibilizer of low molecular weight, there is used at least one compound selected from compounds containing, in the molecule, at least one of carboxyl group, acid anhydride group, acid amide group, imide group, carboxylate group, amino group, isocyanate group, group having oxazoline ring and hydroxyl group. Examples of these compounds are aliphatic carboxylic acids, aromatic carboxylic acids, esters, acid anhydrides and acid amides of these acids, imides derived from these acids and/or acid anhydrides, aliphatic glycols or phenols, isocyanates such as toluene diisocyanate and methylenebis-(4-phenyl isocyanate), oxazolines such as 2-vinyl-2-oxazoline, aliphatic amines, aliphatic diamines, aliphatic triamines, aliphatic tetramines, aromatic amines such as m-phenylenediamine, 4,4'-methylenedianiline and benzidine. The following unsaturated compounds are more preferred.

0023Typical examples are maleic anhydride, maleic acid, fumaric acid, maleimide, maleic acid hydrazide, a reaction product of maleic anhydride and diamine, e.g., compounds having the formulas <chemistry id="chem0002" num="0002"><img file="EP0262901B2_D0002.tif" /></chemistry> wherein R is an aliphatic or aromatic group, methylnadic anhydride, dichloromaleic anhydride, maleic acid amide and, natural fats and oils such as soybean oil, tung oil, caster oil, linseed oil, hempseed oil, cottonseed oil, sesame oil, rapeseed oil, peanut oil, camellia oil, olive oil, coconut oil and sardine oil; unsaturated carboxylic acid such as acrylic acid, butenoic acid, crotonic acid, vinyl acetic acid, methacrylic acid, pentenoic acid, angelic acid, tiglic acid, 2-pentenoic acid, 3-pentenoic acid, α-ethylacrylic acid, β-methylcrotonic acid, 4-pentenoic acid, 2-hexenoic acod, 2-methyl-2-pentenoic acid, 3-methyl-2-pentenoic acid, α-ethylcrotonic acid, 2,2-dimethyl-3-butenoic acid, 2-heptenoic acid, 2-octenoic acid, 4-decenoic acid, 9-undecenoic acid, 10-undecenoic acid, 4-dodecenoic acid, 5-dodecenoic acid, 4-tetradecenoic acid, 9-tetradecenoic acid, 9-hexadecenoic acid, 2-octadecenoic acid, 9-octadecenoic acid, eicosenoic acid, docosenoic acid, erucic acid, tetracocenoic acid, mycolipenic acid, 2,4-pentadienic acid, 2,4-hexadienic acid, diallyl acetic acid, geranic acid, 2,4-decadienic acid, 2,4-dodecadienic acid, 9,12-hexadecadienic acid, 9,12-octadecadienic acid, hexadecatrienic acid, linolic acid, linolenic acid, octadecatrienic acid, eicosadienic acid, eicosatrienic acid, eicosatetraenic acid, ricinoleic acid, eleosteric acid, oleic acid, eicosapentaenic acid, erucic acid, docosadienic acid, docosatrienic acid, docosatetraenic acid, docosapentaenic acid, tetracosenoic acid, hexacosenoic acid, hexacodienoic acid, octacosenoic acid, and tetraaconitic acid; or ester, acid amide or anhydride of these unsaturated carboxylic acids; unsaturated oxazoline; unsaturated alcohol such as allyl alcohol, crotyl alcohol, methylvinyl carbinol, allyl carbinol, methylpropenyl carbinol, 4-penten-1-ol, 10-undecene-1-ol, propargyl alcohol, 1,4-pentadiene-3-ol, 1,4-hexadiene-3-ol, 3,5-hexadiene-2-ol, 2,4-hexadiene-1-ol, alcohol of the formula: C_nH_2n-5OH, C_nH_2n-7OH or C_nH_2n-9OH (n is an integer), 3-butene-1,2-diol, 2,5-dimethyl-3-hexene-2,5-diol, 1,5-hexadiene-3,4-diol or 2,6-octadiene-4,5-diol; and unsaturated amine such as that where an OH group of the unsaturated alcohol is replaced by an -NH₂ group.

0024Isocyanates such as toluene diisocyanate and methylenediphenyl diisocyanate are also included. There may be further included various polymers and rubbers of low molecular weight (e.g., 500 - 10,000) into which said compatibilizing agents are introduced.

0025Mutual compatibilizers of high molecular weight include polymers of high molecular weight (e.g., more than 10,000) into which said compatibilizers of low molecular weight are introduced. Preferred are polyethylene, polypropylene and polyolefin copolymers such as ethylene-propylene coplymer and ethylene-butene copolymers, and above mentioned polyamides, thermoplastic polyesters, and polyphenylene sulfide, polyacetal and polyether ether ketone into which compatibilizing agent of low molecular weight is introduced. These polymers include those copolymerized with other components. Further preferred are modified rubber-like materials.

0026"Modified rubber-like materials" in this invention mean those obtained by modification of rubber-like materials.

0027"Rubber-like material" in this invention mean natural and synthetic polymer materials which are elastic at room temperature.

0028As examples of rubber-like materials, mention may be made of natural rubber, butadiene polymer, isoprene polymer, chlorobutadiene polymers, butadiene-acrylonitrile copolymer, isobutylene polymer, isobutylene-butadiene copolymer, isobutylene-isoprene copolymer, acrylate ester copolymer, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-propylene-diene copolymer, Thiokol rubber, polysulfide rubber, polyurethane rubber, polyether rubber e.g., polypropylene oxide, epichlorohydrin rubber, polyester elastomer and polyamide elastomer.

0029These rubber-like materials may be produced by any method (e.g., emulsion polymerization or solution polymerization) and with any catalyst (e.g. a peroxide, trialkylaluminum, lithium halide or nickel catalyst).

0030Furthermore, there may also be used those which have various crosslinking degrees, various proportions of micro structures (e.g., cis structure, trans structure, vinyl group, etc.) or various average rubber particle sizes.

0031Various polymers such as random copolymers, block copolymers and graft copolymers may be used as the copolymers for rubber-like materials in this invention.

0032Modification of rubber-like materials may be effected by any method of introduction of at least one mutual compatibilizer of low molecular weight mentioned above. Generally, this is effected by copolymerization (including all of random copolymerization, block copolymerization, graft copolymerization, etc.) and reaction with main chain, side chain and terminal of molecule.

0033The compositional ratio of (A), (B) and (C) in the resin composition comprising (A) dispersing phase of polyphenylene ether, (B) polyamide matrix phase and (C) mutual compatibilizer compatible with (A) and/or (B) is preferably (A) 1 - 60%, (B) 40 - 98.9% and (C) 0.1 - 30% and most preferably (A) 1 - 60%, (B) 40 - 98.9% and (C) 0.1 - 20% (wherein % is by weight). When (A) is less than 1% by weight, the composition is inferior in heat resistance, dimension stability and processability and when more than 65% by weight, the dispersing phase is not formed and impact strength and processability are inferior. When (B) is less than 35% by weight, the matrix phase is not formed and impact strength and processability are deteriorated. When (B) is more than 98.9% by weight, heat resistance, dimension stability, hygroscopicity and processability are not improved. When (C) is less than 0.1% by weight, the phases become unstable and impact strength decreases. When (C) is more than 50% by weight, gelation occurs and deteriorates processability and besides, the matrix (B) is hardly formed and the phase is unstable, reducing impact strength.

0034The average particle size in the polyphenylene ether dispersing phase (A) is 0.01 - 10µm, preferably 0.05 - 5 µm, more preferably 0.05 - 3µm. Further preferred particle size is 0.1 - 2µm, more preferably 0.1 - 1.8µm. When the particle size is outside the above range, impact strength decreases.

0035The resin composition of this invention may further contain (D) fibrous reinforcing composites having an aspect ratio (ratio of major axis and minor axis) of at least 10 such as glass fiber, carbon fiber, polyamide fiber and metallic whisker or (E) inorganic filler (excluding fibrous filler) having an average particle size of 10µm or less such as silica, alumina, calcium carbonate, talc, mica, carbon black, TiO₂ and ZnO.

0036In a case where the fibrous reinforcing composite material (D) or the inorganic filler (E) is added, addition amount thereof is 1 - 50 parts by weight per 100 parts by weight of the resin composition comprising (A) the disperse phase comprising polyphenylene ether, (B) the polyamide matrix phase and (C) the mutual compatibilizer.

0037One preferred embodiment of this invention may be to use the resin composition in the form of a composite material wherein flame retardants such as Sb203 or flame retardant aids; lubricants; nuclear agents; plasticizers; dyes; pigments; antistatic agents; antioxidants; weatherability providing agents, etc. are added.

0038Any process is used to prepare the present resin composition.

0039Melt-blending methods for the components are the best from an economical point of view, although it is possible to blend the components in a solution and evaporate the solvent or precipitate in a non-solvent. Melt-blending is carried out in a single-screw or a twin-screw extruder, a kneader or so, preferably a highspeed twin-screw extruder.

0040Before kneading, it is preferable to uniformly blend powder or pellets of the component resins in a tumbler or a Henschel mixer. The first blending above is not always necessary. Alternatively, each resin may be fed to a kneader through a metering apparatus. Resin composition, after kneaded, is molded according to injection, extrusion and the like. Alternatively, dry blending the resin materials at the injection or extrusion molding without prekneading and direct kneading are made in the melt processing to produce a shaped article. Any order is used in the kneading step. For example, (A) and (B), and (C) are kneaded together, or (A) and (B) are first kneaded before (C) is then kneaded or, preferably, (A) and (C) are first kneaded before compound (B) is then kneaded. It is not desirable to knead compounds for (B) and (C) and then add compound for (A), because gellation occurs and a desirable resin composition is not produced.

0041The resin composition of this invention is used as shaped articles, sheets, tubes, films, fibers, laminates, coating materials, etc. made by injection molding or extrusion molding, especially as automobile parts such as bumper, inverness, fender, trim, door panel, wheel cover, side protector, garnish, trunk lid, bonnet, roof, etc., interior and exterior materials and mechanical parts required to have heat resistance. Furthermore, the resin composition is used as parts for motor bicycles such as covering material, muffler cover, leg shield, etc. and electrical and electronic parts such as housing, chassis, connector, base for printed circuit, pulley and other parts required to have strength and heat resistance.

0042This invention is explained referring to examples below, wherein they are merely illustrative ones and this invention is not limited to them. Heat distortion temperature test (H.D.T.), Izod impact strength test (3.2 mm thick) and M.I. are observed in accordance with JIS K7207, JIS K7110 and JIS K7210, respectively.

0043Polyphenylene ether and modified rubber-like materials used in the examples and comparative examples are obtained below.

(1) Polyphenylene ether:

0044Manganese chloride/ethylenediamine is added to a solution of 2,6-dimethylphenol in toluene and methanol and then the solution is subjected to oxidation polymerization under a molecular oxygen atmosphere at 30°C.

(2) Modified rubber-like material:

0045A mixture of ethylenepropylene rubber, maleic anhydride and tert-butyl peroxylaurate is extruded from an extruder (screw diameter: 30 mm; L/D = 28; barrel temperature: 230°C; screw rotation: 60 rpm). Modified rubber strands extruded are cooled in water and pelletized,

(3) Polyamide:

0046<tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Polyamide 6,6</entry><entry namest="col2" nameend="col2" align="left">UBE Nylon ® 2020B (Ube Industries, Ltd.)</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Polyamide 6</entry><entry namest="col2" nameend="col2" align="left">UBE Nylon ® 1013B (Ube Industries, Ltd.)</entry></row></tbody></tgroup></table></tables>

Example 1

004740 wt% of polyphenylene ether ηsp/c = 0.47 dl/g (reduced viscosity measured in 0.5 g/dl chloroform at 25°C), 50 wt% of polyamide 66 "UBE Nylon" ® 2020B and 10 wt % of maleic anhydride grafted ethylene propylene rubber (amount of maleic anhydride grafted: 0.7 wt % of ethylene propylene rubber) were melted and kneaded at resin temperature of 310°C and screw rotation of 500 rpm in a continuous twin-screw kneader (TEX-44 ® of Nippon steel Manufacturing Co. Ltd.) and the product was granulated and test specimens were made therefrom by an injection molding machine (IS-150 of Toshiba Co.). Properties of the test specimens were measured. The results are shown in Table 1.

0048An Izod impact strength test specimen before subjected to the test was subjected to finishing on its cross section by microtome and dipped in carbon tetrachloride which is a good solvent for polyphenylene ether for 30 minutes at room temperature to etch polyphenylene ether. This test specimen was examined by a scanning type electron microscope to measure diameter of dispersed particles of polyphenylene ether. Weight average particle size was calculated on the basis of maximum size of each particle. The results are also shown in Table 1.

Comparative Example 1

0049Example 1 was repeated except that polyphenylene ether of ηsp/c = 0.25 was used. The results are shown in Table 1.

Example 2

0050Example 1 was repeated using 40 wt % of polyphenylene ether (ηsp/c = 0.52), 50 wt% of polyamide 6 "UBE Nylon" ® 1013B and 10 wt % of maleic anhydride grafted ethylene propylene rubber. The results are shown in Table 4.

Example 3

0051Example 2 was repeated except that polyamide 66 "UBE Nylon"® 2020B was used in place of polyamide 6. The results are shown in Table 2.

0052From these examples and comparative examples, it will be seen that Izod impact strength increases with decrease in average particle diameter of disperse phase comprising polyphenylene ether and decreases to a practically unacceptable value when the particle diameter exceeds 10 µ and thus the particle diameter of disperse phase of polyphenylene ether is an important factor.

0053It has been found that this dispersed particle diameter varies depending on molecular weight of polyphenylene ether, kind of the compatibilising agent and kneading method. These are surprising facts unexpectable from the conventional technique on polyphenylene ether composition.

Example 4

0054Example 1 was repeated except that polyphenylene ether of ηspc = 0.55 was used. The results are shown in Table 1.

0055Surprisingly, it is seen from Table 1 that reduced viscosity of polyphenylene ether has a suitable range and when it is less than 0.40, diameter of dispersed particles increases to cause reduction of Izod impact strength and when it reaches 0.60, the diameter also tends to increase.

Example 6

005640 wt% of polyphenylene ether (ηsp/c = 0.47 dl/g), 50 wt% of polyamide 66 "UBE Nylon" ® 2020B and 10 wt% of maleic anhydride grafted ethylene propylene rubber (amount of maleic anhydride: 97 wt% of the ethylene propylene rubber) were kneaded at 260°C for 5 minutes in a small batchwise twin-screw kneader "LABOPLASTMIL" ® at a screw rotation of 90 rpm. The resulting composition was pressed (270°C) to produce test specimens and properties thereof were measured. The results are shown in Table 3.

Example 7

0057Example 6 was repeated except that the kneading was effected at 280°C The results are shown in Table 3.

0058It is recognized from Examples 6 and 7 that even if composition is the same. particle diameter of disperse phase of polyphenylene ether changes and further impact strength markedly changes with change in kneading conditions That is, importance of diameter of dispersed particles is clearly shown.

Example 8

005950 wt% of polyphenylene ether (ηsp/c = 047 dl/g), 10 wt% of maleic anhydride grafted ethylene propylene rubber (amount of maleic anhydride grafted: 0.7 wt% of ethylene propylene rubber) and 0.6 part by weight (based on the total composition) of maleic anhydride were introduced into a twin-screw continuous kneader ("TEX-44"® of Nippon Steel Manufacturing Co., Ltd.) from its first hopper and 40 wt% of polyamide 6 "UBE Nylon" ® 1013B was introduced from second hopper provided between the first hopper and vent hole and they were melted and kneaded at resin temperature of 310°C - 340°C and a screw rotation of 380 rpm and then granulated. Then, test specimens were made by an injection molding machine (IS-150E of Toshiba Machine Co.. Ltd.) and properties were measured The results are shown in Table 4.

Example 9

0060Example 8 was repeated except that ethylene propylene rubber was used in place of maleic anhydride grafted ethylene propylene rubber. The results are shown in Table 4.

Example 10

0061Example 10 was repeated except that 10 wt% of 2-vinyl-2-oxazoline grafted polystyrene ("RPS" ® of Dow Chemical Co.) was used in place of 0.6 part by weight of the maleic anhydride and amount of polyphenylene ether was changed to 40 wt%. The results are shown in Table 4. <tables id="tabl0002" num="0002"><img file="EP0262901B2_D0003.tif" /></tables><tables id="tabl0003" num="0003"><img file="EP0262901B2_D0004.tif" /></tables><tables id="tabl0004" num="0004"><img file="EP0262901B2_D0005.tif" /></tables>

0062It has been found from the above examples and comparative examples that in composition of polyphenylene ether, polyamide and mutual compatibilizer, the particle diameter of dispersing phase of the polyphenylene ether has conspicuous effects on impact strength and is 0.01 - 10 µm, preferably 0.05 - 5 µm, more preferably 0.05 - 3 µm, further preferably 0.1 - 2 µm, the most preferably 0.1 - 1.8 µm.

0063As explained above, the resin composition of this invention comprises a dispersing phase consisting polyphenylene ether, a polyamide and a mutual compatibilizer which is compatible with both or either one of said two phases. The impact strength of this composition, which has not been improved by conventional techniques, can be improved with substantially no reduction in heat resistance by specifying a particle diameter of the polyphenylene ether phase.

0064Especially, hitherto no attention has been given to the fact that the diameter of dispersed particles in a composition containing polyphenylene ether has a great effect on impact strength and so a rubber component must have been used in a large amount in order to improve impact strength which is accompanied by reduction of heat resistance.

0065This invention can provide more readily a novel composition having a superior balance between impact strength and heat resistance by specifying a particle diameter for the disperse phase of polyphenylene ether, using a mutual compatibilizer which serves to obtain the specific particle diameter and specifying the molecular weight of polyphenylene ether.

0066The novel composition provided by this invention can be processed into a shaped article, e.g. a sheet, film, tube or coating material by processing methods employed for thermoplastic resins such as injection molding, extrusion molding, to afford articles having an excellent balance of properties such as heat resistance, impact strength, processability and dimension stability.