AROMATIC POLY(THIOETHERAMIDE-IMIDES)

Abstract: An aromatic poly(thioetheramide-imide) has a recurring unit of the following general formula (II): wherein each -Ar-, which may be the same or different represents a divalent aromatic residue. Preparation is by reacting an aromatic diamine H₂N-C₆H₄-S-Ar-S-C₆H₄-NH₂ with trimellitic anhydride or its chloride, preferably in a polar organic solvent in the presence of a HCl trapping agent, followed by dehyd­ ration. The polymer is moldable optionally with a filler, to form a shaped product, film or fibres of good strength.

Description: The present invention relates to aromatic polythioetheramide-imides that can be used widely for parts in the electric and electronic fields, housings, automobile parts, aircraft interior parts, sliding parts, gears, insulating materials, heat-resistant films, heat-resistant varnishes, and heat-resistant fibers. It is known that aromatic polyamide-imides that are excellent in their balance of mechanical properties and heat resistance can be obtained by polycondensation of aromatic tricarboxylic anhydrides or their derivatives with aromatic diamines. However, aromatic polyamide-imides that have hitherto been generally proposed are unsatisfactory in that they are poor in melt moldability and will partially decompose under some molding conditions. To improve the moldability, various methods have been suggested such as the following: 1. A method that uses aromatic diamines having an ether linkage as disclosed in Polymer Preprints , 15 (1), page 761 (1974). 2. A method that improves the moldability by copolymerization as disclosed in Japanese Laid-Open Patent Application No. 91724/1983. However, these methods are in practice unsatisfactory in view of the balance of moldability, heat resistance and mechanical strength which are taken into consideration as a whole. GB-A-1 082 694 discloses infusible polythioetheramide - imide coatings manufactured from trimellitic anhydride. There is no mention of using the acid chloride. An object of the present invention is to provide aromatic polythioetheramide-imides that are excellent in the balance of machanical properties, heat resistance and moldability. According to the present invention we provide aromatic poly(thioetheramide-imide) having a glass transition temperature of 150 to 300 °C and an inherent viscosity (in a N-methylpyrrolidone solution containing 0.2 % by weight of the polymer) at 30 °C of at least 0.2 dl/g, and having the recurring units of the following general formula (II): wherein -Ar-, which may be the same or different in the polymer, each represents a divalent aromatic residue, the polymers having been produced by (a) stirring a solution in an organic polar solvent of an aromatic diamine of formula (I) and trimellitic anhydride chloride at a temperature of -20° to 80°C for 1 to 10 hours in the presence of a hydrogen chloride trapping agent and (b) dehydrating the resultant polyamideamic acid in the liquid phase by chemical ring closing or thermal ring closing at 50°C to 400°C or by heating the solid polymer at 150° to 350°C. We also provide a process of preparing these polymers by reacting 1 mol of at least one aromatic diamine having a thioether linkage of the following general formula (I): wherein -Ar-, which may be the same or different, each represents a divalent aromatic residue, with 0.99 to 1.01 mol of trimellitic anhydride chloride of the following formula: These novel polymers have a recurring unit of the following general formula (II): wherein -Ar-, which may be the same or different in the polymer, each represents a divalent aromatic residue. Examples of aromatic diamines used as starting materials, having a thio-ether linkage of the general formula (I), include 1,4-bis(4-aminophenylthio)benzene, 1,3-bis(4-aminophenylthio)-benzene,2,4-bis(4-aminophenythio)nitrobenzene, 2,5- dimethyl-1,4-bis(4-aminophenylthio)benzene, 4,4' -bis(4-aminophenylthio)biphenyl, 4,4'-bis(4-aminophenylthio)diphenyl ether, 4,4'-bis(4-aminophenylthio)diphenyl sulfide, 1,4-bis[4-(4-aminophenylthio)phenylthio]benzene, α,ω-diaminopoly(1,4-thiophenylene) oligomer, 4,4'-bis(4-aminophenylthio)benzophenone, 4,4'-bis(4-aminophenylthio)diphenyl sulfoxide, 4,4'-bis(4-aminophenylthio)diphenyl sulfone, 3,3'-bis(4-aminophenylthio)diphenyl sulfone, 2,2-bis[4-(4-aminophenylthio)phenyl]propane and 4,4'-bis(4-aminophenylthio)diphenylmethane. Of these, preference is given to those diamines having as -Ar- a divalent aromatic residue of the following general formula: wherein A represents -O-, -CO-, -SO-, -SO₂- or -C y H 2y - in which y is an integer of from 1 to 10, Y represents an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, halogen or a nitro group, a, b, c, d, e and f each is 0 or an integer of from 1 to 4, and x is a number of from 0 to 20. The aromatic polythioetheramide-imides of the present invention are prepared by the aforesaid methods, as disclosed in Japanese Patent Publication No. 15637/1967 (GB 1056564A). In this preparation method, the raw materials are relatively readily available and a higher degree of polymerization can be attained under moderate conditions. The method of preparing the polymers is now further described in detail below. First Step : 1.00 mol of at least one aromatic diamine having a thioether linkage of the following general formula (I): wherein -Ar- has the same significance as in the above general formula (I), and 0.99 to 1.01 mol of trimellitic anhydride chloride are dissolved in an organic polar solvent, and the solution is stirred at a temperature of -20°C to +80°C and preferably -10°C to +30°C for 1 to 10 hours in the presence of a hydrogen chloride trapping agent to produce a polyamide-amic acid having a recurring unit of the following general formula: wherein -Ar- has the same significance as in the above general formula (II). As organic polar solvents used in the first step can be mentioned organic polar aprotic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, N,N-dimethylbenzamide, N-methylpyrrolidone, N-methylpiperidone, N-methyl-ε-caprolactam, hexamethylphosphoramide, tetramethylurea, sulfolane, dimethyl sulfoxide, and the mixtures thereof, with N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone being particularly preferred. Suitable chloride trapping agents added in the first step include (a) aliphatic tertiary amines (e.g., trimethylamine, triethylamine, tributylamine, etc.), (b) cyclic organic bases (e.g., pyridine, quinoline, pyrimidine, 2,6-lutidine), (c) alkali metal hydroxides, (d) alkali metal carbonates, (e) alkali metal acetates, (f) alkaline earth metal oxides, (g) alkaline earth metal hydroxides, (h) alkaline earth metal carbonates, (i) alkaline earth metal acetates, and (j) organic oxide compounds (e.g., ethylene oxide or propylene oxide). However, if an organic acid amide type solvent such as N-methylpyrrolidone is used as a reaction solvent, a hydrogen chloride trapping agent is not necessarily added. Second Step : The polyamide-amic acid obtained in the first step is dehydrated to perform a ring closing reaction to produce the aromatic polythioetheramide-imide of the present invention. This step can be carried out in either a liquid phase or a solid phase. The ring closing method in the liquid phase can be either a thermal ring closing process or a chemical ring closing process. In the thermal ring closing process, the polyamide-amic acid solution is heated to 50 to 400°C and preferably 120 to 250°C. In this case, it is more effective to use an azeotropic solvent useful for the removal of water such as benzene, toluene, xylene or chlorobenzene. In the chemical ring closing process, to the polyamide-amic acid solution is added (a) an aliphatic anhydride (e.g., acetic anhydride, propionic anhydride, etc.), (b) a halogen compound (e.g., phosphorus oxychloride, thionyl chloride) or (c) a chemical dehydrator (e.g., molecular sieves, silica gel, alumina, phosphorus pentachloride), and the reaction is carried out at 0 to 120°C and preferably 10 to 60°C. The aromatic polythioetheramide-imide produced by a ring closing reaction in the liquid phase is present generally in the state of a solution, and therefore, the solution is diluted with a solvent that does not dissolve the polymer but is compatible with the reaction solvent so as to precipitate the polymer, which is filtered off to be isolated. On the other hand, in the ring closing method in the solid phase, the polyamide-amic acid solution is charged into water or methanol to isolate the polymer and the polymer is heat-treated at 150 to 350°C. However, care should be taken since the balance of mechanical properties and fluidity of the polymer when melted will be lowered if the polymer is heated at a high temperature of 250°C or above for a longer period. The Polymer The aromatic polythioetheramide-imides of the present invention have a glass transition temperature of 150 to 300°C, and the inherent viscosity of an N-methylpyrrolidone solution containing 0.2% by weight of the polymer at 30°C is at least 0.2 dℓ/g. When the polymer of the present invention is molded, various known filler components can be added. Typical examples of filler components include (a) fibrous fillers such as glass fiber, carbon fiber, boron fiber, aramid fiber, alumina fiber,or silicon carbide fiber, and (b) inorganic fillers such as mica, talc, clay, graphite, carbon black, silica, asbestos, molybdenum sulfide, magnesium oxide or calcium oxide. The present invention will now be illustrated by reference to the following Examples. In the accompanying drawings: Figures 1 and 2 show the infrared absorption spectrum charts of the aromatic polythioetheramide-imides obtained as described in Example 2 and 4 respectively. EXAMPLE 1 10.7 g of 4,4'-bis(4-aminophenylthio)benzophenone (0.025 mol) and 20 mℓ of N-methylpyrrolidone were charged into a 500 mℓ four-necked flask equipped with a thermometer, a water separator having a Liebig condenser, a solid inlet, and a nitrogen gas inlet. Then, 5.26 g of trimellitic anhydride chloride (0.025 mol) in the solid form were added to the mixture at 0°C under a flow of nitrogen with vigorous stirring. Thereafter, the stirring was continued for 2 hours while the temperature is allowed to increase gradually to room temperature. Then, 20 mℓ of N-methylpyrrolidone (NMP) and 20 mℓ of toluene were added and the mixture was heated at 150°C for 4 hours. The water produced during the treatment was azeotropically removed together with the toluene. After the reaction mixture was cooled to room temperature, the mixture was charged into water to allow the produced polymer to precipitate, and the polymer was filtered, ground, washed with water, and dried at 150°C for 8 hours in a vacuum oven to obtain the aromatic polythioetheramide-imide having the following physical properties in a yield of 14.5 g (99% of theory). Inherent viscosity: 0.60 dℓ/g (measured at 30°C as an NMP solution containing 0.2 wt% of the polymer). Glass transition temperature: 240°C. Thermal decomposition starting temperature: 448°C. Infrared absorption spectrum (according to the Nujol method): 1780 cm⁻¹ and 1720 cm⁻¹ (imide), 1640 cm⁻¹ and 1525 cm⁻¹ (amide), 1640 cm⁻¹ (ketone), 1080 cm⁻¹ (thioether), and 820 cm⁻¹, 760 cm⁻¹ and 720 cm⁻¹ (aromatic ring). When this polymer was compression moulded at 320°C, a yellow tough resin plate having a tensile strength of 870 kg/cm² and a tensile modulus of 2.6 x 10⁴ kg/cm² was obtained. EXAMPLE 2 Example 1 was repeated except that 10.7 g of 4,4'-bis(4-aminophenylthio)benzophenone was substituted for 8.1 g of 1,4-bis(4-aminophenylthio)benzene (0.025 mol), resulting in an aromatic polythioetheramide-imide having the following physical properties in a yield of 11.8 g (98% of theory). Inherent viscosity: 0.20 dℓ/g (measured at 30°C as an NMP solution containing 0.2 wt% of the polymer). Glass transition temperature: 214°C. Softening point: 349°C. Infrared absorption spectrum (according to the Nujol method; see Figure 1): 1775 cm⁻¹ and 1720 cm⁻¹ (imide), 1650 cm⁻¹ and 1520 cm⁻¹ (amide), 1080 cm⁻¹ (thioether) and 810 cm⁻¹, 760 cm⁻¹ and 720 cm⁻¹ (aromatic ring). This polymer could be compression molded at 360°C. It was confirmed that this polymer had a recurring unit of the following formula: EXAMPLE 3 Example 1 was repeated except that 10.7 g of 4,4'-bis(4-aminophenylthio)benzophenone was substituted for 10.8 g of 4,4'-bis(4-aminophenylthio)diphenyl sulfide (0.025 mol), resulting in a polymer having the following physical properties in a yield of 14.6 g (99% of theory). Inherent viscosity: 0.25 dℓ/g (measured at 30°C as an NMP solution containing 0.2 wt% of the polymer). Glass transition temperature: 184°C. Softening point: 298°C. Infrared absorption spectrum (according to the Nujol method): 1770 cm⁻¹ and 1715 cm⁻¹ (imide), 1640 cm⁻¹ and 1510 cm⁻¹ (amide), 1070 cm⁻¹ (thioether) and 805 cm⁻¹, 760 cm⁻¹ and 720 cm⁻¹ (aromatic ring). This polymer could be compression molded at 310°C. EXAMPLE 4 Example 1 was repeated except that 10.7 g of 4,4'-bis(4-aminophenylthio)benzophenone was substituted for 11.6 g of 4,4'-bis(4-aminophenylthio)diphenyl sulfone (0.025 mol), resulting in a polymer having the following physical properties in a yield of 15.3 g (99% of theory). Inherent viscosity: 0.30 dℓ/g (measured at 30°C as an NMP solution containing 0.2 wt% of the polymer). Glass transition temperature: 253°C. Infrared absorption spectrum (according to the Nujol method; see Figure 2): 1775 cm⁻¹ and 1720 cm⁻¹ (imide), 1650 cm⁻¹ and 1610 cm⁻¹ (amide), 1150 cm⁻¹ (sulfone), 1070 cm⁻¹ (thioether) and 820 cm⁻¹, 760 cm⁻¹ and 720 cm⁻¹ (aromatic ring). This polymer could be compression molded at 300°C and had a recurring unit of the following formula: EXAMPLE 5 Example 1 was repeated except that 10.7 g of 4,4'-bis(4-aminophenylthio)benzophenone was substituted for 10.0 g of 4,4'-bis(4-aminophenylthio)biphenyl (0.025 mol), resulting in a polymer having the following physical properties in a yield of 13.8 g (99% of theory). Inherent viscosity: 0.42 dℓ/g (measured at 30°C as an NMP solution containing 0.2 wt% of the polymer). Glass transition temperature: 253°C. Infrared absorption spectrum (according to the Nujol method): 1775 cm⁻¹ and 1720 cm⁻¹ (imide), 1640 cm⁻¹ and 1510 cm⁻¹ (amide), 1080 cm⁻¹ (thioether) and 805 cm⁻¹, 760 cm⁻¹ and 720 cm⁻¹ (aromatic ring).

Claims: A melt-moldable aromatic poly(thioetheramide-imide) having a glass transition temperature of 150 to 300 °C and an inherent viscosity (in a N-methylpyrrolidone solution containing 0.2 % by weight of the polymer) at 30 °C of at least 0.2 dl/g, and having the recurring units of the following general formula (II): wherein -Ar-, which may be the same or different in the polymer, each represents a divalent aromatic residue, the polymers having been produced by (a) stirring a solution in an organic polar aprotic solvent of 1 mol of an aromatic diamine having a thioether linkage of the general formula: wherein -Ar- represents a divalent aromatic residue, and 0.99 to 1.01 mol of trimellitic anhydride chloride at a temperature of -20° to 80°C for 1 to 10 hours in the presence of a hydrogen chloride trapping agent and (b) dehydrating the resultant polyamide-amic acid (i) in the liquid phase by chemical ring closing or thermal ring closing at 50° to 400°C or (ii) by heating the solid polymer at 150° to 350°C. An aromatic poly(thioetheramide-imide) as claimed in Claim 1, wherein said divalent aromatic residue has the following general formula: or wherein A represents -O-, -CO-, -SO-, -SO₂- or -H y H 2y - in which y is an integer of from 1 to 10, Y represents an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, halogen or a nitro group, a, b, c, d, e and f each is 0 or an integer of from 1 to 4, and x is a number of from 0 to 20. A process of preparing a melt-moldable aromatic poly(thioether-amide-imide) having a glass transition temperature of 150 to 300 °C and an inherent viscosity (in a N-methylpyrrolidone solution containing 0.2 % by weight of the polymer) at 30 °C of at least 0.2 dl/g, and having the recurring units of the following general formula (II): wherein -Ar-, which may be the same or different in the polymer, each represents a divalent aromatic residue, which process comprises (a) stirring a solution in an organic polar aprotic solvent of 1 mol of an aromatic diamine having a thioether linkage of the general formula: wherein -Ar- represents a divalent aromatic residue, and 0.99 to 1.01 mol of trimellitic anhydride chloride at a temperature of -20° to 80°C for 1 to 10 hours in the presence of a hydrogen chloride trapping agent which is not essential if the polar solvent is an organic acid amide, so as to form a polyamide-amic acid, and (b) dehydrating the resultant polyamide-amic acid (i) in the liquid phase by chemical ring closing or thermal ring closing at 50° to 400°C or (ii) by heating the isolated solid polymer at 150° to 350°C. A molded product made from a polymer as claimed in Claim 1 or 2, optionally with a filler.

Inventors: ARITOMI, MITSUTOSHI MITSUBISHI PETROCHEM. CO. LTD., TERAUCHI, MAKOTO MITSUBISHI PETROCHEM. CO. LTD.
Applicants: MITSUBISHI PETROCHEMICAL CO., LTD.
Application year: 1986
Main classification: C08G73
IPC codes: C08G75, C08G73, C08G69