Heat resistant resin composition

Abstract: Heat resistant resin compositions consisting essentially of 5-95 wt.% of polyimide composed of recurring units represented by the formula (I): wherein X and Y are the same as defined in the claims, and 95-5 wt.% of known aromatic polyetherimide are disclosed. The resin compositions of this invention have good thermal stability in the high temperature region, particularly in the temperature range of 300-400°C. The compositions can be injection molded due to the retention of frictional property in aromatic polyetherimide and also have thermal resistance, impact resistance and abrasion resistance. Therefore the compositions can be widely used as the material of parts in any industrial fields such as automotives, business machines, electric and electronic appliances, automatic energy saving devices, aeronautics and space instruments and general purpose industrial machines, which renders this invention very valuable.

Description: This invention relates to a heat resistant resin composition. Polyimide obtained by the reaction of aromatic tetracarboxylic acid dianhydride with diamine is excellent in mechanical strength, dimensional stability, flame retardance, electrical insulation and chemical resistance in addition to having high-temperature resistance. Therefore, polyimide has so far been used in the field of electrical and electronic parts, aeronautics and space instruments, transport machinery and business machine members, and is hereafter expected to be widely used in fields where heat resistance is required. Although many kinds of polyimide which have been developed to date exhibit excellent properties, generally they have a high softening temperature and are insoluble in solvents, thereby causing difficulties in moulding. For example, a polyimide consisting of a polymer chain having repeating units represented by the following formula: (Trade Mark KAPTON and VESPEL, products of E.I. du Pont de Nemours and Co.) indicates no distinct glass transition temperature and has excellent heat resistance. The polyimide, however, is difficult to process by hot moulding. Aromatic polyetherimide (Trade Mark ULTEM, a product of General Electric Co.) is known to possess better processability than conventional polyimide. The typical aromatic polyetherimide has repeating units represented by the following formula: In spite of having imide linkages in the molecule similarly to conventional polyimide, polyetherimide can be fusion moulded and is excellent in mechanical strength, flame retardance, electrical properties and moulding ability, and thus is expected to be widely used. Aromatic polyetherimide, however, has a low heat distortion temperature of about 200°C as compared with that of conventional polyimide of 280°C. Accordingly, reduction of mechanical and abrasion properties at high temperatures has caused problems in the development of its application. In order to alleviate these disadvantages solid lubricants such as graphite, fluorine-containing-resin, titanium oxide and molybdenum disulfide have been added to the aromatic polyetherimide in combination with or separately from inorganic fillers such as glass fibres and carbon fibres. However, the addition of inorganic fillers leads to lower abrasion resistance and the addition of solid lubricants tends to cause marked reduction in mechanical strength. In addition, a method for the simultaneous use of aromatic polyetherimide and another resin such as aromatic polyamideimide has also been developed. Even in such a case, however, retention of mechanical strength, particularly impact and abrasion resistance, has still been unsatisfactory. Our own European Application Serial No. 235 294, discloses polyimides having repeating units represented by the formula: in which R represents an aliphatic group having two or more carbon atoms, a cycloaliphatic group, a monocyclic aromatic group, a fused ring polycyclic aromatic group, or a non-fused ring polycyclic aromatic group where the aromatic groups are linked to each other directly or through a linking member. These polyimides are said to be excellent heat-resistant adhesives. An object of this invention is to achieve a heat resistant resin composition having mechanical strength, particularly impact and abrasion resistance, at high temperatures, while maintaining other excellent properties such as flame retardance, good electrical properties, mechanical strength and mouldability which are the important characteristics of aromatic polyetherimides. According to the present invention, a heat resistant resin composition consists essentially of 90 to 5 weight % of an aromatic polyetherimide not containing recurring units of formula I and 10 to 95 weight % of a polyimide composed of recurring units represented by the formula I: in which X is a direct bond or -S-, and Y is an aliphatic group having at least two carbon atoms, an alicyclic group, a monocyclic aromatic group, a fused polycyclic aromatic group or a polycyclic aromatic group where the aromatic rings are connected to one another by a direct bond or by a bridging group. The aromatic polyetherimide which is used in this invention may be that described in Polymer Preprint 24 , (2), 312-313 (1983). That polyetherimide is a polymer consisting of ether and imide linkages as a required bonding unit and is substantially composed of recurring units which are represented by the following formula: in which Z is a trifunctional aromatic group where two functional groups out of the three are connected with adjacent carbon atoms, and both Q and Ar are residues of divalent aromatic groups. Representative examples of such aromatic polyetherimides include the compounds having recurring units represented by the following formulae: (p=0.1 ∼ 0.3, q=0.9 ∼ 0.7) Some of the above aromatic polyetherimides are commercially available from General Electric Co. with trade marks such as ULTEM-1000, ULTEM-4000 and ULTEM-6000. As the diamine component of the reaction to produce the polyimide having recurring units of formula I, an etherdiamine may be used represented by the formula: in which X is a direct bond or -S-. The etherdiamine is reacted with at least one tetracarboxylic acid dianhydride, and the resulting polyamic acid is subjected to dehydrating condensation to obtain the corresponding polyimide. Thus, the etherdiamines contemplated for use in this invention are 4,4'-bis(3-aminophenoxy)biphenyl and bis[4-(3-aminophenoxy)phenyl]sulfide. these diamines can be used alone or as a mixture. In addition, other diamines can be included with the etherdiamine in a range which will cause no adverse effect on the flowability of the molten polyimide. Diamines which may be used in admixture with the etherdiamine include, for example, m-aminobenzylamine, p-aminobenzylamine, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylether, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4′-bis(4-aminophenoxy)biphenyl, 4,4′-bis(4-aminophenoxy)ketone, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]methane, 1,1-bis[4-(3-aminophenoxy)phenyl]ethane, 1,2-bis[4-(3-aminophenoxy)phenyl]ethane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2-[4-(3-aminophenoxy)phenyl]-2-[4-(3-aminophenoxy)-3-methylphenyl]propane, 2,2-bis[4-(3-aminophenoxy)-3-methylphenyl]propane, 2-[4-(3-aminophenoxy)phenyl]-2-[4-(3-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(3-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]butane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4′-bis(3-aminophenoxy)biphenyl, 4,4′-bis(3-aminophenoxy)-3-methylbiphenyl, 4,4′-bis(3-aminophenoxy)-3,3′-dimethylbiphenyl, 4,4′-bis(3-aminophenoxy)-3,5-dimethylbiphenyl, 4,4′-bis(3-aminophenoxy)-3,3′,5,5′-tetramethylbiphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide and bis[4-(3-aminophenoxy)phenyl]sulfone. These diamines can be used in admixture with the etherdiamine of the above formula (II) in an amount of normally not more than 30 wt.%, and preferably not more than 5 wt.%. The polyimide can be prepared by reacting the aforesaid diamine with tetracarboxylic acid dianhydride in an organic solvent, followed by conducting dehydrating condensation. The tetracarboxylic acid dianhydride used in this process has the following formula: where Y is the same as above. Representative examples of these tetracarboxylic acid dianhydrides include ethylenetetracarboxylic acid dianhydride, 1,2,3,4-butanetetracarboxylic acid dianhydride, cyclopentanetetracarboxylic acid dianhydride, pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 2,2',3,3'-benzophenonetetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 1,2,3,4-benzenetetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,3,6,7-anthracenetetracarboxylic acid dianhydride, 1,2,7,8-phenanthrenetetracarboxylic acid dianhydride, 4,4'-(p-phenylenedioxy)diphthalic acid dianhydride and 4,4'-(m-phenylenedioxy)diphthalic acid dianhydride. Among these acid dianhydrides, pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride are particularly preferred. The tetracarboxylic acid dianhydrides can be used alone or as a mixture of two and more. The heat resistant resin composition of this invention consists essentially of 90 to 5 weight % of the aromatic polyetherimide and 10 to 95 weight % of the polyimide. A preferred composition consists of 90 to 10 weight % of aromatic polyetherimide and 10 to 90 weight % of polyimide. A more preferred composition consists of 80 to 20 weight % of aromatic polyetherimide and 20 to 80 weight % of polyimide. When the content of the aromatic polyetherimide or the polyimide is above 95 weight % or below 5 weight %, the composition cannot provide the desired combination of excellent characteristics i.e. flowability, mechanical strength and particularly impact and abrasion resistance. The composition of this invention may also include fillers such as are commonly used in resin compositions, in an amount which has no adverse effect on the desired properties. Possible fillers include abrasion resistance improvers such as graphite, carborundum, silica powder, molybdenum disulfide and fluorine-containing-resin; reinforcing materials such as glass fibres, carbon fibres, boron fibres, silicon carbide fibres, carbon whiskers, asbestos and metal fibres; flame retardance improvers such as antimony trioxide, magnesium carbonate and calcium carbonate; electrical property improvers such as clay and mica; tracking resistance improvers such as asbestos, silica and graphite; acid resistance improvers such as barium sulfate, silica and calcium metasilicate; thermal conductivity improvers such as iron powder, zinc powder, aluminum powder and copper powder; and other miscellaneous additives such as glass beads, glass spheres, talc, diatomaceous earth, alumina, silicate balloons, hydrated alumina, metal oxides, colouring agents and other materials which are stable above 300°C. The starting materials for the composition are mixed in advance. The mixing may be carried out by feeding each material separately to fusion mixing equipment, or by mixing the materials in a general purpose mixer, such as a Henschel mixer, ball mixer or ribbon blender, prior to feeding the materials to the fusion mixer. The temperature of the fusion mixer will normally be 250 to 400°C and preferably 300 to 380°C. Any moulding process, including compression moulding, sinter moulding, injection moulding and extrusion moulding, may be employed. Injection moulding and extrusion moulding are recommended, from the viewpoint of obtaining a uniformly fused blend and high productivity. The present invention will hereinafter be further illustrated by way of Synthesis Examples, Examples of moulding and Comparative Examples. Unless otherwise specified, % and part respectively mean % by weight and part by weight. Synthesis Example 1 A reaction vessel equipped with a stirrer reflux condenser and nitrogen inlet tube was charged with 4.0 kg (10 moles) of 4,4'-bis(3-aminophenoxy)diphenyl sulfide and 34.8 kg of N,N-dimethylacetamide. The mixture had added to it 2.14 kg (9.8 moles) of pyromellitic dianhydride in a nitrogen atmosphere at room temperature, with care taken to avoid temperature rise of the solution, and the mixture stirred for about 20 hours at room temperature. To the polyamic acid solution obtained, 2.02 kg (20 moles) of triethylamine and 2.55 kg (25 moles) of acetic anhydride were added dropwise in a nitrogen atmosphere at room temperature. The reaction mixture was stirred for about 20 hours to obtain a light yellow slurry. The slurry was filtered, washed with methanol, filtered again and dried at 180°C for 8 hours under reduced pressure to obtain 5.64 kg (about 97.5% yield) of polyimide powder. The inherent viscosity of the polyimide powder was 0.85 dl/g. The inherent viscosity was measured at 35°C after dissolving 0.5 g of the polyimide powder in 100 ml of a solvent (a mixture of p-chlorophenol and phenol in the ratio of 90:10) at elevated temperature. Examples 1-4 and Comparative Examples 1-2 The polyimide powder obtained in Synthesis Example 1 was dry blended with aromatic polyetherimide powder (Trade Mark; ULTEM 1000, a product of General Electric Co. in U.S.A.) in the ratios of Table 1 and the blend pelletized by extruding at 370 to 400°C with a twin screw extruder. The pellets thus obtained were fed to an injection moulding machine having a cylinder temperature of 360 to 390°C, an injection pressure of 1000 kg/cm² and a mould temperature of 100 to 150°C. The injection moulded specimens were measured as to their mechanical and abrasion properties. Some of the pellets obtained were fed to a Brabender type viscosimeter (Trade Mark; Laboplastomill, a product of Toyo Seiki Seisakusho Ltd.). Melt torque was measured under the conditions of 385°C temperature and 50 rpm rotor revolution. The results obtained are given in Table 1. Thermal properties were measured with a rectangular specimen having dimensions of 6 x 3 x 3 mm. The glass transition temperature Tg was measured with a thermo-mechanical analysis instrument (Trade Mark; TM-30, a product of Shimadzu Seisakusho Ltd.). Heat distortion temperature was examined with a load of 18.6 kg/cm² in accordance with ASTM D-648. Impact strength with a 1/8 inch (approximately 3.2 mm) notch was tested in accordance with ASTM D-256. Coefficient of abrasion was measured with a thrust abrader at a sliding velocity of 128 m/min and a surface pressure of 0.78 kg/cm². (Hereinafter the same testing methods as in Examples 1 to 4 were employed for all Examples and Comparative Examples.) Synthesis Examples 2-5 The same procedures as in Synthesis Example 1 were carried out except that various diamines were used in place of 4,4'-bis(3-aminophenoxy)diphenyl sulfide, various tetracarboxylic acid dianhydrides were used, and the amounts of the diamines, N,N-dimethylacetamide and tetracarboxylic acid dianhydrides were changed. As a result, various kinds of polyimide powder were obtained. Table 2 gives the materials and quantities used to prepare the polyimides and the inherent viscosities of the polyimides obtained. Examples 5-15 and Comparative Examples 3-5 The polyimide powder obtained in Synthesis Examples 2-5 was kneaded with aromatic polyetherimide powder (Trade Mark; ULTEM 1000, a product of General Electric Co. in U.S.A.) by fusing in various mixing ratios to obtain uniformly blended pellets. The pellets obtained were moulded under the same conditions as described in Example 1. Thermal, mechanical and abrasive properties were measured on the moulded specimens and are given in Tables 4-7. The polyimides used in these Examples and Comparative Examples are given in Table 3. Polyimide Example No. Comparative Example No. Table No. Synthesis Example 2 5 - 7 3 4 Synthesis Example 3 8 - 11 4 5 Synthesis Example 4 12 - 13 - 6 Synthesis Example 5 14 - 15 5 7 Synthesis Example 3 16 - 18 - 8 Examples 16-18 The polyimide powder obtained in Synthesis Example 3 was kneaded with aromatic polyetherimide powder (Trade Mark; ULTEM 6000, a product of General Electric Co. in U.S.A.) by fusing in various mixing ratios to obtain uniformly blended pellets. The pellets obtained were moulded under the same conditions as described in Example 1. Thermal and mechanical properties were measured on the moulded specimens and are given in Table 8. Example 16 17 18 Polymer (wt.%) Aromatic polyetherimide (ULTEM 6000) 10 50 90 Polyimide (Polymer obtained in synthesis Example 3) 90 50 10 Property Glass transition temperature (°C) 258 256 242 Heat distortion temperature (°C) 238 236 221 Izod impact strength (notched) (kg. cm/cm) 18.3 17.0 12.0

Claims: A heat resistant resin composition consisting essentially of 90 to 5 weight % of an aromatic polyetherimide not containing recurring units of formula I and 10 to 95 weight % of a polyimide composed of recurring units represented by the formula I: in which X is a direct bond or -S-, and Y is an aliphatic group having at least two carbon atoms, an alicyclic group, a monocyclic aromatic group, a fused polycyclic aromatic group or a polycyclic aromatic group where the aromatic rings are connected to one another by a direct bond or by a bridging group. A heat resistant resin composition as claimed in Claim 1 in which Y is a residue of pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride or 3,3',4,4'-biphenyltetracarboxylic acid dianhydride. A heat resistant resin composition as claimed in Claim 1 or Claim 2 in which X is a direct bond. A heat resistant resin composition as claimed in Claim 1 or Claim 2 in which X is -S-. A heat resistant resin composition as claimed in any preceding claim in which the aromatic polyetherimide is composed of recurring units represented by the formula: in which Z is a trifunctional aromatic group where two functional groups out of the three are connected with adjacent carbon atoms, and both Q and Ar are residues of divalent aromatic groups.

Inventors: OHTA MASAHIRO, YOSHIKAWA MASAO, OHTA, MASAHIRO, YOSHIKAWA, MASAO
Applicants: MITSUI TOATSU CHEMICALS, NTN TOYO BEARING CO LTD, MITSUI TOATSU CHEMICALS, INC., NTN CORPORATION
Application year: 1988
Main classification: C08L79
IPC codes: C08L79