Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D179/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen, with or without oxygen, or carbon only, not provided for in groups C09D161/00 - C09D177/00
  • C09D179/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
  • C09D179/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors

Definitions

• the present invention relates to a coating composition
• a coating composition comprising a polyimide soluble in organic solvents (soluble polyamide) and a film formed therefrom.
• Polyimide is known as an egineering plastic, which has substantially constant heat resistance, electric insulation, mechanical properties such as flexibility, etc., and radiation resistance in a relatively wide temperature range from a very low temperature to a high temperature (e.g. 250 to 300°C), and is used in aerospace industries, electric and electronic industries which lay severe conditions to materials.
• the polyimide has imide bonds in the backbone, and usually prepared by the polycondensation of an acid anhydride and a diamine.
• an aromatic polyimide comprising an aromatic acid anhydride and an aromatic diamine has good heat resistance.
• Aromatic polyimide is supplied in the form of a film or a molded article. Usually, the film and the molded article are not directly produced from the aromatic polyimide, since many aromatic polyamides do not have a clear melting point or there is no solvent suitable for dissolving the aromatic polyamides as such.
• a polyamic acid which is a precursor of an aromatic polyamide is dissolved in a solvent to form a solution, and then the solution is processed to form a film and so on, as disclosed in JP-A-10-96826 and JP-A-10-171265.
• the solution of the precusor polyamic acid is stored and treated under dry conditions, since the polyamic acid is easily decomposed and has low storage stability.
• the processing of the polyamic acid solution involves heating to remove the solvent and also to convert the precursor to the aromatic polyimide through a dehydration ring- closing reaction (imidation reaction) . In the imidation reaction, water is formed as a by-product.
• aromatic polyamides which can be soluble in the solvents after the completion of imidation are known.
• the soluble aromaci polyimides are prepared using diphenylsulfone-3,3',4,4'-tetracarboxylic anhydride as an acid anhydride, and commercially available in the name of RIKACOAT from SHIN-NIPPON RJKA KABUSHIKIKAISHA.
• the soluble aromatic polyimides can form an aromatic polyimide films without the imidation during the removal of the organic solvents. Although applicable to other polyimide films, the films of the soluble aromatic polyimides have low mechanical properties, in particular, tear strength, if the aromatic polyimide films have good mechanical properties as well as good heat resistance, they can be widely used as intermediate transfer belts of machines such as electrophtographyic copying machines, flexible print circuits (FPC), or other structural members, electronic parts, optical parts, etc.
• machines such as electrophtographyic copying machines, flexible print circuits (FPC), or other structural members, electronic parts, optical parts, etc.
• One object of the present invention is to provide a coating composition comprising a soluble aromatic polyimide which has good heat resistance and mechanical strength, and the film formed from such a soluble aromatic polyimide.
• the present invention provides a coating composition comprising a polyimide soluble in organic solvents, wherein said polyimide is a compound of the formula (I):
• R's represent independently from one another a hydrogen atom, a halogen atom, a C]-C ⁇ 0 alkyl group or a -Cio alkoxy group, a phenyl group, or a phenyl group which is substituted with 1 to 4 halogen atoms and/or C C ⁇ o alkyl groups;
• A is a C 6 -C 20 tetravalent aromatic group or a group of the formula (II):
• B is a covalent bond, a >C(R 2 ) 2 group, a carbonyl group, an oxygen atom, a sulfur atom, a >SO 2 group, a >Si(CH 3 ) 2 group, a >Si(C 2 H 5 ) 2 group, a >NR 3 group or a bifunctional ether group in which R 2 is a hydrogen atom or C(R ) 3 R 3 is a hydrogen atom, a C ⁇ -C 20 alkyl group or a C 6 -C 2 o aryl group, and R 4 is a hydrogen atom, a fluorine atom or a chlorine atom;
• Ar is a monocyclic or polycyclic C 6 -C 20 , aromatic nucleus or a group of the formula (HI):
• Ar and B are the same as defined above, and each p is an integer of 0 to 10; m is an integer of 1 to 10, and said polyimide has a weight average molecular weight of 150,000 to 1,000,000 in terms of a polystyrene molecular weight measured with gel permeation chromatography.
• the present invention provides a coating composition
• a polyimide soluble in organic solvents wherein said polyimide is a polycondensate polymer of 3,3 ',4,4' -biphenyltetracarboxylic dianhydride, a diamine having an aromatic ether group, a 9, 9-bis (4-amylaryl) fluorene, znc optionally pyromellitic dianhydride (1,2,4,5- benzenetetracarboxylic dianhydride), and said polyimide has a weight average molecular weight of 150,000 to 1,000,000 in terms of a polystyrene molecular weight measured with gel permeation chromatography.
• the present invention provides a film formed from the above coating composition of the present invention.
• the coating composition of the present invention is prepared by dissolving the soluble polyimide in an organic solvent.
• the polyimide is the aromatic polyimide having a plurality of pendant fluorene structural units, as represented by the formula (I) .
• the pendant fluorene structural units allow the polyimide to be dissolved in the organic solvent.
• the chemical structure of the formula ( ) will be explained in detail.
• the four R groups included in one repeating unit are independent from one another. That is, they may be the same or different.
• Each R is a hydrogen atom, a halogen atom, a C C ⁇ 0 alkyl group or a Ci-Ci 0 alkoxy group a phenyl group, or a phenyl group which is substituted with 1 to 4 halogen atoms and/or C ⁇ -C ⁇ 0 alkyl groups, m is an integer of 1 to 10.
• Raw materials corresponding to the polyamide having such a chemical structure may be commercially available or can be easily synthesized.
• A is a C 6 -C 2 o tetravalent aromatic group or a group of the above formula (II).
• B is a covalent bond, a >C(R 2 ) 2 group, a carbonyl group, an oxygen atom, a sulfur atom, a >SO 2 group, a >Si (CH 3 ) 2 group, a >Si(C 2 H 5 ) 2 group, a >NR 3 group, or a bifunctional ether group (e.g. a group derived from a dihydric phenol such as bisphenol A, from the phenolid hydroxyl groups of which hydrogen atoms are removed).
• a bifunctional ether group e.g. a group derived from a dihydric phenol such as bisphenol A, from the phenolid hydroxyl groups of which hydrogen atoms are removed.
• R 2 is a hydrogen atom or -C (R 4 ) 3
• R 3 is a hydrogen atom, a C ⁇ -C 20 alkyl group or a C 6 -C 20 aryl group
• R 4 is a hydrogen atom, a fluorine atom or a chlorine atom.
• Ar in the formula (I) is a monocyclic or polycyclic C 6 -C 20 , aromatic nucleus or a group of the formula (HI) .
• Two suffixes p in the formula (HI) are the same or different, and each p is an integer of 0 to 10.
• the weight average molecular weight of the soluble aromatic polyimide of the formula (I) is from 150,000 to 1,000,000, preferably from 200,000 to 600,000, in terms of a polystyrene molecular weight measured with gel permeation chromatography (GPC).
• GPC gel permeation chromatography
• a preferable aromatic carboxylic anhydride constituting the soluble aromatic polyimide is 3,3',4,4'-biphenyltetracarboxylic dianhydride.
• the residue derived from such a dianhydride preferably constitutes the group A, since such a group can impart good elasticity to the film or sheet formed from the soluble aromatic polyimide.
• 3,3',4,4'-Biphenyltetracarboxylic dianhydride is commercially available under the trade name of s-
• pyromellitic dianhydride is used as a further aromatic carboxylic anhydride.
• the use of pyromellitic dianhydride decreases the elastic modulus of the film or sheet of the aromatic polyimide, and thus the elastic modulus of the film or sheet can be adjusted in accordance with the applications of the film or sheet.
• the diamine which constitutes the soluble aromatic polyimide preferably has an aromatic ether functional group and in turn, such a functional group constitutes (Ar) m , from the viewpoint of the flexibility of the film or sheet formed from the soluble aromatic polyimide.
• the diamine is diaminodiphenyl ether (ODA) or 1, 3-bis(4-aminophenoxy)benzene, it can impart flexibility to the film or sheet without deteriorating the durability of the polyimide.
• the fluorene is usually 9, 9-bis(4-aminoaryl)fluorene, preferably 9, 9-bis(4- aminophenyl)fluorene (BAF) or 9, 9bis(4-amiono-3-methylphenyl)fluorene (OTBAF), since they can be relatively easily available.
• BAF 9, 9-bis(4- aminophenyl)fluorene
• OTBAF 9, 9bis(4-amiono-3-methylphenyl)fluorene
• the soluble aromatic polyimide maybe prepared as follows:
• the acid anhydride, the diamine and the fluorene derivative are mixed in a specific molar ratio. Then, the mixture is stirred at room temperature for a specific time to form a polyamic acid.
• the polyamic acid is imidated with acetic anhydride and preferably absolute (dry) pyridine. More in detail, acetic anhydride and anhydrous pyridine are added to the polyamic acid to form a solution. Then, the solution is heated at 120° to 140°C while stirring to obtain the aromatic polyimide. Then, the aromatic polyimide is cooled to about 25°C followed by purification with tetrahydrofuran (THF) and water.
• THF tetrahydrofuran
• THF When THF is used, it is possible to isolate high purity aromatic polyimide having a high molecular weight and a saturation solubility in THF of 50 g/liter or less, preferably 10 g/liter or less, from the unreacted monomers, low molecular weight aromatic polyimide and an imidization catalyst used.
• the purified aromatic polyimide is dried to obtain the powder product.
• the polyimide which is produced as described above, has good heat resistance due to its aromatic nature.
• the aromatic polyimide is hardly decomposed since the imidization is completed. As a result, it is not necessary to store or treat the aromatic polyimide under dry conditions.
• the aromatic polyimide is dissolved in the organic solvent to prepare the coating composition.
• the inorganic solvent is not limited in the present invention.
• Preferred examples of the organic solvent include organic polar solvents such as N-methylpyrrolidone
• NMP l,3-dimethyl-2-imidazolidinone, dimethylsulfoxide, N,N,N',N',N",N"-hexamethylphosphorylamide.
• the aromatic polyimide can be dissolved in an amide solvent (e.g. N,N-dimethylformamide (DMF), N,N-dimethylacetoamide, etc.) or an ether solvent (e.g. tetrahydrofuran (THF), dioxane, cyclopentanone, cyclohexanone, etc.).
• amide solvent e.g. N,N-dimethylformamide (DMF), N,N-dimethylacetoamide, etc.
• an ether solvent e.g. tetrahydrofuran (THF), dioxane, cyclopentanone, cyclohexanone, etc.
• the concentration of the aromatic polyimide in the coating composition may be suitable adjusted according to the thickness of the film or sheet formed. Typically, 8 to 20 parts by weight of the aromatic polyimide is dissolved in 92 to 80 parts by weight of the organic solvent. When the amount of the aromatic polyimide dissolved is less than 8 parts by weight, it is necessary to thickly apply the coating composition to form the film or sheet having a desired thickness, and thus it takes a long time to dry the applied composition, on the other hand, it is very difficult to dissolve more than 20 parts by weight of the aromatic polyimide.
• the coating composition can be applied on a substrate with a coating means such as a knife coater at a desired thickness, and then the organic solvent is removed by heating and drying to form a heat resistant film.
• the heating and drying time of the applied solution can be shortened when the soluble aromatic polyimide according to the present invention is used, since the imidation of the aromatic polyimide is completed as explained above, and thus the undesirable by-products (for example, water), which should be removed together with the organic solvent, are not generated, hi particular, in the case of the coating composition comprising the aromatic polyimide and the organic polar solvent, the heating and drying of the applied composition can be completed in a relatively short time, and thus such a composition is suitable for substrates having low heat resistance (for example, electronic parts such as FPC, or optical parts).
• the undesirable by-products for example, water
• the film of the polyimide has good mechanical properties such as tear strength, elastic modulus, etc.
• the tear strength is rather high.
• the film thickness is in the range between 40 and 150 /mi, a tear strength of 160 to 490 N/mm, preferably 185 to 490 N/mm, more preferably 190 to 490 N/mm is achieved.
• the film can be advantageously used as, for example, a conveying belt.
• a conductive film having a volume resistivity of 10 8 to 10 12 ⁇ cm can be obtained.
• the thickness of the film is usually from 50 to 150 ⁇ m, preferably from 70 to 130 ⁇ m.
• the film thickness is less than the lower limit, the film has insufficient strength.
• the film thickness exceeds the upper limit, the film has low flexibility.
• the film having such a thin thickness can produce a belt having sufficient strength.
• the acid anhydride as the raw material of the polyimide is not limited to 3,3',4,4'-biphenyltetracarboxylic dianhydride, and any other carboxylic anhydrides may be used insofar as they are aromatic ones.
• Examples of other acid anhydrides include pyromellitic anhydride, bis(phthalic anhydride)sulfone, bis(phthalic anhydride) ether, 2,2-bis(phenoxyphthalic anhydride)propane, lJJ,3,3,3-hexafluoropropane-2,2bis(phthalic anhydride), 2,3,3',4'-biphenylte tracarboxylic dianhydride, benzophenonetetracarbocylic dianhydride, etc.
• the diamine is not limited to the diamine having the aromatic ether group, and any other diamines may be used insofar as they are aromatic ones.
• the other diamines include bis(4-aminophenyl)methane, 2, 2-bis(4-aminophenyl)propane, phenylenediamine, bis(4- aminophenyl)sulfone, etc.
• the fluorene is not limited to 9, 9-bis(4-aminoaryl)fluorene, and any other fluorene derivatives may be used insofar as they are bifunctional ones.
• the other fluorene derivatives include 9, 9-bis(4-aminophenoxyphenyl)fluorene, etc.
• the solution was cooled to about 25 °C, and dropwise added to 3 liters of THF to obtain a precipitate.
• the precipitate was once isolated from THF by decantation, washed with water, immersed in 1.5 liters of THF for 18 hours, and again isolated from THF by decantation.
• the isolated precipitate was heated and dried in an oven at about 100°C for 18 hours to obtain a powdery aromatic polyimide.
• the weight average molecular weight of the obtained aromatic polyamide was measured with gel permeation chromatography, and was about 290,000 in terms of the polystyrene molecular weight.
• NMP N-methylpyrrolidone
• the aromatic polyimide film was peeled off from the substrate and its tear strength was measured according to JIS K 7128-3.
• the tear strength of the film of this Example was 265 N/mm.
• An aromatic polyimide was synthesized, and a film was produced therefrom and evaluated in the same manner as in Example 1 except that 52.26g of BAS, lO.Olg of 3,4'-ODA and 58.84g of s-BPDA were used.
• the polyimide had a weight average molecular weight was about 250,000 in terms of a polystyrene molecular weight measured with gel permeation chromatography, and the film had a tear strength of 167 N/mm.
• the polyimide had a weight average molecular weight was about 260,000 in terms of a polystyrene molecular weight measured by gel permeation chromatography. A film was produced from this polyimide and evaluated. It had a tear strength of 216 N/mm.
• the powdery aromatic polyimide prepared in Example 3 (50g) was dissolved in 45 Og of NMP to obtain a coating composition containing 10% by weight of the aromatic polyimide. Then, the coating composition was uniformly applied with a knife coater having a gap length of 900 ⁇ m on an inner wall surface of a hollow cylinder of stainless steel having an inner diameter of 438 mm and a width of 50 mm. Then, the cylinder carrying the coating composition applied was dried with a hot air using a drier at about 80°C for 8 hours to obtain a seamless film (or an endless loop film).
• the seamless film was removed from the hollow cylinder and heated at about 250°C for 30 minutes to remove substantially all the solvent.
• the heated seamless film had a thickness of about 75 ⁇ m.
• the tear strength of the seamless film was 235 N/mm when measured according to HS F 7128-3.
• a heated seamless film was produced in the same manner as in Example 4 except that a coating composition was prepared by dissolving and dispersing 30g of the powdery polyamide and conductive titanium oxide (FT2000 manufactured by ISHIHARA SANGYO KAISHA, LTD.) in 270g of NMP.
• the tear strength of the seamless film was 167 N/mm when measured according to JIS K 7128-3.
• a film was prepared and evaluated in the same manner as in Example 1 except that a solution of a polyamide (RIKACOAT SN 20 (trade name) manufactured by SHIN-NIPPON RLKA KABUSHIKIKAJSHA,L weight average molecular weight of about 130,000 in terms of a polystyrene molecular weight measured by gel permeation chromatography)
• the tear strength of the film was 147 N/mm.
• the coating composition of the present invention can be dried in a relatively short time, and molded products such as a film or a sheet produced therefrom have good heat resistance and mechanical strength, in particular, tear strength.

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• Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)
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• 2001
  • 2001-11-30 AU AU2002228685A patent/AU2002228685A1/en not_active Abandoned
  • 2001-11-30 WO PCT/US2001/045092 patent/WO2002044291A2/en not_active Application Discontinuation
  • 2001-11-30 EP EP01989808A patent/EP1354011A2/en not_active Withdrawn
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