POLYIMIDE RESIN COMPOSITION

Abstract: This invention is a polyimide resin composition containing 100 parts by weight of polyimide having recurring units of the following formula : (where Y is a bond, divalent hydrocarbon radical having from 1 to 10 carbons, hexafluorinated isopropylidene radical, carbonyl radical, thio radical, sulfinyl radical, sulfonyl radical or oxide, and R is a tetra-­ valent radical of aliphatic radical having at least 2 carbons, alicyclic radical, monoaromatic radical, condensed polyaromatic radical, or non-­ condensed polyaromatic radical wherein aromatic radicals are mutually connected with a bond or a crosslinking function) and from 5 to 100 parts by weight of fluororesin. The resin composition can provide molded products which are excellent in high-temperature stability, dimensional stability and mechanical strength and moreover have a low friction coefficient and good wear resistance. Therefore, the composition is useful as the material for electric and electronic devices, precision instrument parts etc. Polyimide of this invention can be prepared from aromatic diamines and tetracarboxylic acid dianhydrides. Suitable aromatic diamines are 4,4′-bis(3-aminophenoxy)biphenyl, 2,2-bis[4-(3-amino­ phenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl] sulfide etc. Suitable tetracarboxylic acid dianhydrides are pyromellitic dianhydride and 3,3′, 4,4′-benzophenonetetracarboxylic dianhydride. Representative fluororesin which can be used in this invention is polytetrafluoroethylene.

Description: The present invention relates to a novel polyimide resin composition having excellent sliding properties. Polyimides obtained by reacting tetracarboxylic acid dianhydrides with diamines are hereafter expected to be used for a variety of sliding parts because of their various excellent properties and good high-temperature stability as well as outstanding wear resistance. Many polyimides which have so far been developed exhibit outstanding properties. Even polyimides, however, which have excellent sliding properties and high-temperature stability do not have a definite glass transition temperature. Therefore, it is difficult to process these polyimides by injection molding and special procedures are required for preparing products having desired shapes. On the other hand, polyimide resin having a low glass transition temperature and excellent processability is restricted as regards its use for sliding parts by the upper limit of its application temperature. Thus the performance of polyimide has both merits and drawbacks. An object of this invention is to provide a novel polyimide resin composition for use as a material for high performance sliding parts. Such sliding parts have excellent high-temperature stability and solvent resistance in addition to the sliding property. Furthermore they can be molded in a variety of shapes by relatively simple injection molding technology. The object of this invention is, more specifically, to provide a polyimide resin composition having an extraordinarily low coefficient of friction together with outstanding wear resistance and capable of being used for precision machine parts. Machine parts which may be made include, for example, various types of bearing component, piston rings, piston skirts, gears, hoppers, slides, various kinds of pump component, cams, rollers, packings and many types of valve part. The present inventors have investigated extensively to achieve the above objective. As a consequence, they have found that a polyimide resin composition comprising a novel polyimide and a specific amount of a fluororesin is particularly effective. Accordingly, the present invention provides a polyimide resin composition which comprises 100 parts by weight of a polyimide having recurring units of the formula: (where Y is a direct bond, or a divalent hydrocarbon radical having from 1 to 10 carbon atoms, a hexafluorinated isopropylidene radical, a carbonyl radical, a thio radical, a sulfinyl radical, a sulfonyl radical or oxygen, and R is a tetra-valent radical selected from aliphatic radicals having 2 or more carbon atoms, alicyclic radicals, monocyclic aromatic radicals, fused polycyclic aromatic radicals, and polycyclic aromatic radicals wherein the aromatic radicals are linked to one another either by a direct bond or via a bridging group); and from 5 to 100 parts by weight of a fluororesin. The polyimide resin which can be used in the present invention is a polyimide prepared by reacting an ether-diamine represented by the following formula: (where Y is a direct bond, or a divalent hydrocarbon radical having from 1 to 10 carbon atoms, a hexafluorinated isopropylidene radical, a carbonyl radical, a thio radical, a sulfinyl radical, a sulfonyl radical or oxygen) with a tetracarboxylic acid dianhydride. Suitable ether-diamines which can be used include 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, 2,2-bis[4-(3-aminophenoxy)phenyl]butane, 2,2-bis[4-(3-amino-phenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4'-bis(3-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfoxide, bis[4-(3-aminophenoxy)phenyl]sulfone and bis[4-(3-aminophenoxy)phenyl]ether. Representative diamines which can be particularly preferred in the present invention include 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 4,4'-bis(3-aminophenoxy)biphenyl and bis[4-(3-aminophenoxy)phenyl]sulfide. These ether-diamines may be used alone or in mixtures of two or more. Tetracarboxylic dianhydrides for use in the method of this invention have the following formula: (where R is a tetra-valent radical selected from aliphatic radicals having not less than two carbons, cycloaliphatic radicals, monocyclic aromatic radicals, fused polycyclic aromatic radicals, and polycyclic aromatic radicals wherein the aromatic radicals are linked to one another either by a direct bond or via a bridging group). Illustrative dianhydrides which can be used in the method include, for example, ethylenetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,2′,3,3′-biphenyltetracarboxylic dianhydride, 2,2-bis)3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane 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 dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride and 1,2,7,8-phenanthrenetetracarboxylic dianhydride. Representative dianhydrides which can be particularly preferred in this invention include pyromellitic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, and bis (3,4-dicarboxyphenyl) sulfone dianhydride. These tetracarboxylic dianhydrides may be used alone or in mixtures of two or more. The ether-diamine and the tetracarboxylic dianhydride are reacted by a known method to give a polyamic acid represented by the following formula: (where Y is a direct bond, or a divalent hydrocarbon radical having from 1 to 10 carbon atoms, a hexafluorinated isopropylidene radical, a carbonyl radical, a thio radical, a sulfinyl radical, a sulfonyl radical or oxygen, and R is a tetra-valent radical selected from aliphatic radicals, having 2 or more carbon atoms, alicyclic radicals, monocyclic aromatic radicals, fused polycyclic aromatic radicals, and polycyclic aromatic radicals wherein the aromatic radicals are linked to one another either by a direct bond or via a bridging group); and the polyamic acid is successively subjected to dehydration and ring-closing reaction to obtain polyimide. The term fluororesin as used herein means synthetic high polymers containing fluorine atoms in the molecule. When compared with other synthetic resins, the fluororesin excels in high-temperature stability, chemical resistance and electrical properties (high-frequency properties in particular), and provides a specific low friction property and non-tackiness. Representative fluororesins which can be used in the present invention are those having the following rational formulas; and at least one of the resins is used. The fluororesins include, for example, (1) (CF₂CF₂) n : Polytetrafluoroethylene (PTFE) (2) (CF₂CF₂) n [CF(CF₃)CF₂] p : Tetrafluroethylene hexafluoropropylene copolymer (FEP), (3) (CF₂CF₂) n [CF(OC m H 2m+1 )CF₂] p : Tetrafluoroethylene perfluoroalkylvinylether copolymer (PEA), (4) (CH₂CH₂) n [CF₂CF₂] p : Ethylene tetrafluoroethylene copolymer (ETFE), (5) (CH₂CH₂) n [CFClCF₂] p : Ethylene chlorotrifluoroethylene copolymer (ECTFE) and (6) (CF₂CH₂) n : Polyvinylidene fluoride (PVDF). Polytetrafluoroethylene (PTFE) is used most preferably among the fluororesins in this invention. The polytetrafluoroethylenes which are commercially available include, for example, TEFLON KPL-610 (a trade mark of Du Pont . Mitsui Fluoro Chemicals Co., Ltd.) The fluororesin for use in this invention is usually in powder form and its grain size is in the range of about 1 to about 25 microns, preferably about 5 to about 10 microns. The fluororesin in this invention is contained in an amount of from 5 to 100 parts by weight, preferably from 10 to 60 parts by weight per 100 parts by weight of the polyimide. When the content is less than the above-mentioned range, the composition does not have the desired properties. On the other hand, when the content exceeds this range, the composition is hardly further improved in its properties but rather is there a detrimental effect on the wear resistance and mechanical strength of sliding parts made from the composition. The polyimide composition in the practice of this invention can be prepared by the usually known methods and preferably by the following methods in particular. (1) The polyimide powder and the fluororesin are premixed by using a mortar, Henschel mixer, drum blender, tumbler blender, ball mill, ribbon blender etc. The resultant mixture is then kneaded by a known fusion mixer or hot roll to form pellets or powder. (2) The polyimide powder is pre-dissolved or suspended in an organic solvent. The fluororesin is added to the resulting solution or suspension and uniformly dispersed. Then the solvent is removed by heating in a hot air oven. The residual mass is pelletized or powdered. The organic solvents used in this method include, for example, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethyl-methoxyacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl] ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, pyridine, picoline, dimethyl sulfoxide, dimethyl sulfone, tetramethylurea, hexamethylphosphoramide, m-cresol, p-chlorophenol and anisole. There solvents can be used alone or in mixtures of two or more. (3) The polyamic acid precursor of the polyimide is dissolved in the aforesaid organic solvent. The fluororesin is suspended in the resultant solution, followed by imidization by subjecting to a heat treatment at a temperature of from 100 to 400°C or a chemical imidization with a known imidizing agent. The solvent is then removed and the residue is pelletized or powdered. The polyimide resin composition of this invention may also have added to it at least one solid lubricant. Suitable solid lubricants which may be used include, for example, molybdenum disulfide, graphite, boron nitride, lead monoxide and lead powder. In addition, one or more reinforcing materials may be added. Representative reinforcing materials which may be added include, for example, glass fibre, carbon fibre, aromatic polyamide fibre, potassium titanate fibre, and glass beads. Furthermore, the composition of this invention may have added one or more known additives in a range such that the objective of this invention is still attained. Illustrative additives include antioxidants, heat stabilizers, ultra violet absorbers, flame retardants, auxiliary flame retardants, antistatic agents, lubricants, and colorants. In practical applications, the polyimide resin composition of this invention may be molded by known processing methods such as injection molding, extrusion molding, rotation molding etc. EXAMPLES The present invention will be hereinafter illustrated by examples of synthesis of the diamines, followed by examples of production of the polyimide/fluororesin product and some comparative examples of compositions outside the scope of the invention. Synthesis example 1 A 3 l glass reaction vessel was charged with 186 grams (1.0 mol) of 4,4'-dihydroxybiphenyl, 438 grams (2.6 mols) of m-dinitrobenzene, 363 grams of potassium carbonate and 2,000 ml of N,N-dimethylformamide. The mixture was reacted at a temperature of 145-150°C for 16 hours. After completing the reaction, the resultant mixture was cooled and filtered to remove potassium nitrite. The solvent was distilled off from the filtrate under reduced pressure. The residue was cooled to 65°C, 2,000 ml of methanol were added and the mixture stirred for an hour. The resulting crystals were filtered, washed with water, washed with methanol and dried to obtain 426 grams (99.5% yield) of 4,4'-bis(3-nitrophenoxy)biphenyl as brown crystals. In the next step, a 1 l glass reaction vessel was charged with 100 grams (0.23 mol) of crude 4,4'-bis)3-nitrophenoxy)biphenyl, 10 grams of active carbon, 1 gram of ferric chloride hexahydrate and 500 ml of 2-methoxyethanol. The mixture was stirred for 30 minutes under reflux and then 46 grams (0.92 mol) of hydrazine hydrate were added dropwise during 3 hours at 70-80°C. The reaction was terminated by stirring for 5 hours at 70-80°C after ending the dropwise addition. The reaction mixture was cooled, filtered to remove the catalyst and poured into 500 ml of water. The separated crystals were filtered, 48 grams of 35% hydrochloric acid and 540 ml of 50% isopropyl alcohol were added and the mixture warmed. The solution thus obtained was allowed to cool. The separated 4,4'-bis(3-aminophenoxy)biphenyl hydrochloride was filtered, 540 ml of 50% isopropyl alcohol were added and the mixture warmed. The solution thus obtained had added to it 5 grams of active carbon, and was then filtered and neutralized with aqueous ammonia. The separated crystals were filtered, washed with water and dried to give 72.0 grams (85% yield) of 4,4'-bis(3-aminophenoxy)biphenyl as colorless crystals having a melting point of 144-146°C. The purity was 99.6% according to high-speed liquid chromatography. Synthesis example 2 A 1 l glass reaction vessel was charged with 85.6 grams (0.375 mol) of 2,2-bis(4-hydroxyphenyl)propane, 151.2 grams (0.9 mol) of m-dinitrobenzene, 124.6 grams of potassium carbonate and 660 ml of N,N-dimethyl formamide. The mixture was reacted for 10 hours at a temperature of 145-150°C. After completing the reaction, the resultant mixture was cooled and filtered to remove potassium nitrite. The solvent was distilled off from the filtrate under reduced pressure. The residue was cooled to 65°C, 450 ml of methanol were added and the mixture stirred for an hour. The resulting crystals were filtered, washed with water, washed with methanol, and dried to obtain 164.8 grams (93.5% yield) of 2,2-bis[4-(3-nitrophenoxy)phenyl]propane as brown crystals. In the next step, a 500 ml glass reaction vessel was charged with 100 grams (0.21 mol) of 2,2-bis[4-(3-nitrophenoxy)phenyl]propane, 10 grams of active carbon, 1 gram of ferric chloride hexahydrate and 300 ml of 2-methoxyethanol. The mixture was stirred for 30 minutes under reflux and then 42 grams (0.84 mol) of hydrazine hydrate were added dropwise during 2 hours at 70-80°C. The reaction mixture was further stirred for 5 hours at 70-80°C, cooled, filtered to remove the catalyst, and 150 ml of 2-methoxyethanol was distilled off. The residue thus obtained had added to it 270 grams of 20% aqueous hydrochloric acid solution and also 30 grams of sodium chloride, and was then cooled to 20-25°C with stirring. The separated crystals were filtered and neutralized in 30% isopropyl alcohol with aqueous ammonia. The separated crystals were filtered, washed with water, dried and recrystallized from a solvent mixture of benzene and n-hexane. Thus 2,2-bis[4-(3-aminophenoxy)phenyl]propane was obtained in amount 69.2 grams (75% yield) in the form of colorless crystals having a melting point of 106-108°C. The purity was 99. 6% according to high-speed liquid chromatography. Synthesis example 3 A 3 l glass reaction vessel was charged with 218 grams (1 mol) of bis(4-hydroxyphenol) sulfide, 403 grams (2.4 mols) of m-dinitrobenzene, 331 grams (2.0 mols) of potassium carbonate and 2.5 l of N,N-dimethylformamide. The mixture was reacted for 20 hours at a temperature of 145-150°C. After completing the reaction, the resultant mixture was cooled and filtered and the solvent was distilled from the filtrate under reduced pressure. The residue thus obtained had added to it 800 ml of methanol and was stirred for an hour. The crystals obtained were filtered, washed with methanol and dried to give 429 grams (92.3% yield) of bis[4-(3-nitrophenoxy)phenyl] sulfide as crystals. In the next step, 428 grams (0.93 mol) of the crude intermediate was charged into a 3 l glass reaction vessel and 22.6 grams of active carbon, 0.9 gram of ferric chloride hexahydrate and 1.5 l of 2-methoxyethanol were added. The mixture was stirred for 30 minutes under reflux, and then 155.2 grams (3.1 mols) of hydrazine hydrate were added dropwise during 2 hours at 110-115°C. The resultant mixture was further stirred for 3.5 hours under reflux, cooled and filtered to remove the catalyst. The filtrate was concentrated under reduced pressure and 205 ml of 35% hydrochloric acid, 1120 ml of water and 480 ml of isopropyl alcohol were added. The mixture was warmed to obtain a solution, 20 grams of active carbon were added and the mixture was then hot filtered. The filtrate then had added to it 112 grams of sodium chloride, after which it was cooled and the hydrochloride crystals that separated were filtered off. The hydrochloride crystals were neutralized with aqueous ammonia by a known procedure to obtain 265 grams (66% yield) of the desired bis[4-(3-aminophenoxy)phenyl] sulfide as colorless crystals having a melting point of 112.4-113.4°C (corr). The purity was higher than 99.9%. Product Examples 1-4 A reaction vessel equipped with a stirrer, reflux condenser and nitrogen inlet tube was charged with 36.8 kilograms (100 mols) of 4,4'-bis(3-aminophenoxy)biphenyl and 175.8 kilograms of N,N-dimethylacetamide. The mixture had added to it 21.8 kilograms (100 mols) of pyromellitic dianhydride portion by portion at room temperature under a nitrogen atmosphere with care taken to prevent temperature rise of the mixture, and was then stirred for 20 hours at room temperature. The polyamic acid thus obtained had an inherent viscosity of 2.47 dl/g. In the next step, 150 kilograms of the above polyamic acid solution had added to it 337.5 kilograms of N,N-dimethylacetamide, the mixture was warmed to 70°C with stirring under a nitrogen atmosphere, and 26.1 kilograms (26 mols) of acetic anhydride and 9.50 kilograms (9 mols) of triethylamine were added dropwise. Yellow polyimide powder started to separate about 10 minutes after terminating the dropwise addition, and the mixture was further stirred for 2 hours with warming, and then hot filtered. The polyimide powder thus obtained was washed with methanol and dried at 150°C for 5 hours under reduced pressure to afford 34.5 kilograms (98% yield) of polyimide powder. To 100 parts by weight of the polyimide powder above obtained, fluororesin (commercially available TEFLON KPL-610, a trade mark of Du Pont . Mitsui Fluoro Chemicals Co., Ltd.) was added in the various amounts given for Examples 1-4 in Table 1 and in each case mixed in a Henschel mixer (from Kawada Seisakusho). The resultant mixture was kneaded in a molten state at a temperature of 380°C in a single screw extruder having a 30 mm aperture. The strands thus obtained were air-cooled and cut into pellets. The pellets obtained were injection molded with an Arburg injection molding machine having a maximum mold clamping force of 35 tons (35.56 tonnes) under the conditions; injection pressure of 500 kg/cm², cylinder temperature of 400°C, and mold temperature of 180°C. Specimens for measuring the sliding properties were thus prepared. As to the sliding properties, friction coefficient and wear coefficient were measured and the results obtained are given in Table 1. The friction coefficient was measured by rubbing against stainless steel 45C under a sliding load of 10 kg/cm² with a sliding velocity of 6 m/min. The wear coefficient was measured by rubbing against stainless steel 45C under a sliding load of 5 kg/cm² with a sliding velocity of 100 m/min. Product Example 5 To 100 parts by weight of the polyimide powder obtained by the same procedure as in Product Examples 1 to 4, 150 parts by weight of N,N-dimethylacetamide were added to make a suspension. The suspension further had added to it 30 parts by weight of fluororesin having an average diameter of 10 microns (TEFLON KPL-610) which was uniformly dispersed in the mixture. After preliminary drying of the resultant mixture in a hot air oven at 200°C for 20 hours, it was further dried in a vacuum desiccator at 150°C for 5 hours under reduced pressure in order to completely remove the N,N-dimethylacetamide solvent. The powder mixture thus obtained was pelletized by the same procedure as in Product examples 1 to 4 and used to make specimens for testing the physical properties. The physical properties were tested by the same procedure as in Product Examples 1 to 4 and the results are given in Table 1. Product Example 6 To 400 parts by weight of the polyamic acid solution obtained by the same procedure as in Product Examples 1 to 4, 30 parts by weight of the fluororesin used in Product Examples 1 to 4 (TEFLON KPL-610) were added and uniformly dispersed. The resultant mixture was heated and dried by the same procedure as in Product Example 5 to obtain a powder mixture. Then the procedure of Product Example 5 was repeated with the powder mixture to obtain test results which are given in Table 1. Product Examples 7-9 To 100 parts by weight of each of the polyimide powders derived from the diamines and the tetracarboxylic acid dianhydrides which are given for these Examples in Table 1, 30 parts by weight of the fluororesin used in Product Examples 1 to 4 (TEFLON KPL-610) was added. The same further procedures as in Product Examples 1 to 4 were then carried out in each case to obtain the test results as given in Table 1. Product Examples 10-18 To 100 parts by weight of the polyimide powder of Product Examples 1 to 4, 10 parts by weight of the fluororesin used in Product Examples 1 to 4 (TEFLON KPL-610) were added. Separate quantities of this mixture then had added to them, respectively, the solid lubricants or reinforcing materials listed for these Examples in Table 1, in the amounts given in Table 1. The solid lubricants included lead powder, graphite, boron nitride and molybdenum sulfide, having a grain size of 200 to 300 mesh. The reinforcing materials were silane-treated glass fibre having a 3 mm fibre length and a 13 micron fibre diameter (Trade Mark; CS-3PE-476S; from Nitto Boseki Co.), carbon fibre having a 3 mm fibre length and a 12 micron fibre diameter (Trade Mark; TORAYCO, from Toray Industries), aromatic polyamide fibre having a 3 mm fibre length (Trade Mark; KEVLAR, from E.I.Du Pont de Nemours & Co.), and potassium titanate fibre having a 20 micron average fibre length and a 0.2 micron sectional diameter (Trade Mark; TISMO-D from Ohtsuka Chemicals Co.). The resultant compositions were then individually treated and tested by the same procedure as in Product Examples 1 to 4. The test results obtained are given in Table 1. Comparative Examples 1-3 To 100 parts by weight of the polyimide powder of Product Examples 1 to 4, the fluororesin used in Product Examples 1 to 4 (TEFLON; KPL-610) was added in the amounts given in Table 1 for these Comparative Examples. In the case of Comparative Example 1 it will be seen that none was added. The same procedures as in Examples 1 to 4 were then carried out to obtain the test results as given in Table 1.

Claims: A polyimide resin composition which comprises 100 parts by weight of a polyimide having recurring units of the formula: (where Y is a direct bond, or a divalent hydrocarbon radical having from 1 to 10 carbon atoms, a hexafluorinated isopropylidene radical, a carbonyl radical, a thio radical, a sulfinyl radical, a sulfonyl radical or oxygen, and R is a tetra-valent radical selected from aliphatic radicals having 2 or more carbon atoms, alicyclic radicals, monocyclic aromatic radicals, fused polycyclic aromatic radicals, and polycyclic aromatic radicals wherein the aromatic radicals are linked to one another either by a direct bond or via a bridging group); and from 5 to 100 parts by weight of a fluororesin. The polyimide resin composition as claimed in claim 1, wherein Y is a direct bond, an isopropylidene radical or a thio radical. The polyimide resin composition as claimed in claim 1, wherein Y is a direct bond. The polyimide resin composition as claimed in claim 1, wherein Y is an isopropylidene radical. The polyimide resin composition as claimed in claim 1, wherein Y is a thio radical. The polyimide resin composition as claimed in any of claims 1 to 5, wherein R is a tetra-valent radical selected from The polyimide resin composition as claimed in any of claims 1 to 5, wherein R is a tetravalent radical of the form The polyimide resin composition as claimed in any of claims 1 to 5, wherein R is a tetra-valent radical of the form The polyimide resin composition as claimed in any preceding claim, wherein the fluororesin is selected from polytetrafluoroethylene, tetrafluoroethylene hexafluoropropylene copolymer, tetrafluoroethylene perfluoroalkylvinylether copolymer, ethylene tetrafluoroethylene copolymer, ethylene chlorotrifluoroethylene copolymer and polyvinylidene fluoride. The polyimide resin composition as claimed in any of claims 1 to 8, wherein the fluororesin is polytetrafluoroethylene.

Inventors: BABA, KENICHI, KOGA, NOBUHITO, YAMAYA, NORIMASA
Applicants: MITSUI TOATSU CHEMICALS INC.
Application year: 1987
Main classification: C08L79
IPC codes: C08L27, C08L87, C08L79