Other

International Harvester Company

Imi-Tech Corporation

John V Long

John Gagliani

George D Cremer

Methods and compositions for producing imide precursors and polyimide coating and adhesives. Basically a mixture of an oxoimine such as caprolactam, a dianhydride such as 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride and a solvent such as dimethyl formamide is heated to a temperature of about 60.degree. to 120.degree. C. for a suitable period, then the mixture is cooled and a suitable diamine is added to produce the imide precursor. This mixture may be dried to a powder form or may be used directly as a coating or adhesive. The final polyimide is produced by heating the precursor to a suitable temperature over an appropriate period.

Methods and compositions for producing polyimide adhesive bonds

Methods and compositions for producing polyimide coatings

A composition and a process for the preparation of modified polyimide foams possessing outstanding resistance to high humidity environments which comprises the step of preparing a foamable composition by mixing a solution of an ester of benzophenonetetracarboxylic acid dianhydride and caprolactam with a polyamine to form a resin precursor which when heated foams contemporaneously with the polymerization of the reactants. Two solvents with different boiling points are used to produce a two phase system which yields spray dried powders completely free of the lower boiling point solvent.

Steam resistant modified polyimide foams

Methods of making modified polyimide adhesives and laminating compositions. These adhesives are also particularly useful as the matrix material in high strength fiber reinforced composites. The adhesive compositions are prepared by initially reacting an oxoimine with one or more tetracarboxylic acid dianhydrides, which is primarily 1, 2, 3, 4-butanetetracarboxylic acid dianhydride. The resulting bisimide is dissolved in a non-reactive solvent and a suitable diamine is added to react with the bisimide, producing a liquid resin solution which is essentially a polyamide resin solution. This solution is useful as an adhesive or a fiber composite matrix which can be cured to a polyimide at moderate processing temperatures. The final adhesive bond or matrix is found to be flexible, strong and very resistant to flame, high temperatures, oils and solvents.

Polyimide adhesive and method of making from lactam, dianhydride mixture

A method of re-shaping polyimide and modified polyimide foam sheets into selected shapes. Polyimide foam sheets can be made by any of a number of methods, some of which produce sheets of selected thicknesses directly and others of which produce blocks or buns of foam which are sliced into sheets. A sheet is placed in a mold having the desired configuration, such as a half-pipe. The sheet is compressed to about 0 to 99% of the original thickness with heating of one or both major surfaces of the sheet to a temperature of from about 250.degree. to 320.degree. C. for about 0.5 to 5 minutes. Upon removal from the mold, the polyimide foam is found to be self-supporting and to have taken on the mold shape. A moisture impervious densified skin is found on the heated side(s).

Forming techniques for shaping polyimide foams

Methods of making low density modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxime. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder. A suitable hydrated compound which is stable up to at least about 100.degree. C. is mixed with the powder. A foam is then produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. The addition of the hydrated compound is found to result in an exceptionally low density foam. Depending upon heating conditions, a polyimide, polyimide-amide or mixture thereof may be produced, resulting in foams having selectively variable physical properties.

Low density, modified polyimide foams and methods of making same

Methods of producing high molecular weight polyamide-imide foams having superior flame resistance and the foam products produced thereby. Initially, an imidocarboxylic acid is prepared by reacting a suitable oxoimine with a suitable cyclic dianhydride at a temperature of from about 25.degree. to 250.degree. C. in the presence of a solvent or by melt condensation without a solvent. The ratio of oxoimine to dianhydride may be varied to vary the number of imido groups in the final monomer. The imidocarboxylic acid monomer is reacted with an organic isocyanate in the presence of a suitable tertiary diamine catalyst and water to produce the polyamide-imide foam. The material foams spontaneously at room temperature. The reaction may be accelerated by heat or the addition of suitable metal salts. Additives, such as surfactants, flame retardants, fillers, etc., may be added if desired.

Polyamide-imide foams and methods of making same

Methods of making water soluble polyimide resin compositions. A carboxy terminated bisimide is prepared by reacting a suitable aromatic dianhydride with a suitable oxoimine. The bisimide is then mixed with a sufficient quantity of a water soluble solvent to dissolve the bisimide. Water is added to make a solution of the desired viscosity. An aromatic diamine is added to this water solution. To the mixture is added a suitable quantity of a tertiary amine to stabilize the resin. The solution is coated onto a surface and dried to produce a smooth, flexible coating. The coating can then be heated to an appropriate temperature to produce a fully polymerized coating which is thermally stable and resistant to oils and solvents.

Water soluble imide coating composition and method of making from

Methods of foaming and fully curing polyimide resins entirely by the application of microwave energy. Foamable polyimide resins may be prepared by esterifying a suitable dianhydride, reacting the product with a suitable diamine, drying the resulting product and heating to spontaneously form a foam. In the past, such materials could be foamed but could not be satisfactorily cured to a resilient foam entirely by microwave energy. Post-foaming direct application of thermal energy was required to produce a satisfactory foam. We have found that adding a suitable oxoimine, such as caprolactam, to the reaction mixture results in a foam material which is fully and completely cured entirely by the application of microwave energy, considerably simplifying the process and reducing costs.

Foaming and curing polyimide resins by application of microwave energy

Methods of making modified polyimide compositions and the resulting compositions. A polyimide forming material is prepared by treating an aromatic dianhydride with an esterifying solvent, then adding a suitable diamine. In order to obtain a foam which is non-friable and resistant to repeated compressive forces, the selected diamine must contain an aliphatic moiety in the chain. This material is dried to a powder or film. A foam is produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient, flexible non-friable foam.

Polyimide compositions and foams and methods of making same

Methods of making modified polyimide/polyimide-amide foams having selected compressive resistance and density characteristics and the resulting compositions. A suitable aromatic dianhydride is mixed with a suitable oxoimine and alcohol, which initially is believed to form a monoimide which is substantially/simultaneously esterified by the alcohol. To this mixture is added a suitable diamine to produce a polyimide forming material. This material is dried to a powder or film. A foam is produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. Depending upon heating conditions, a polyimide, polyimide-amide or mixture thereof may be produced, resulting in foams having varying physical properties. Within the mole ratio range of oxoimine to dianhydride of about 1.5:1 to about 0.05:1 the compressive resistance of the final foam can be selected in accordance with the intended end use of the foam. Density and compressive resistance varies inversely with the oxoimine quantity in the ratio, being greatest with the 0.05:1 ratio and lowest with the 1.5:1 ratio.

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El Cajon, CA, United States of America

John V Long