United States of America As Represented by the Administrator of Nasa

The United States of America As Represented by the Administrator of the

USA As Represented by Secretary of the Navy

The United States of America As Represented by the United States

Polyone Corporation

Chun-Hua K Chuang

Roger W Avakian

Ling Hu

Ryon Christopher Warren

Raymond D Vannucci

Patrick B Stickler

Frank D MacDonald

Novel aromatic polyimides are disclosed with sufficient physical properties to be useful in 3D printing.

Aromatic polyimides suitable for 3D printing processes

A method for preparing asymmetric 3,4'-(hexafluroisopropylidene) dipthalic anhydride (a-6FDA) and asymmetric 3,4&#x2032;-(methylene)diphthalic anhydride (a-MDPA) from asymmetric 2,3,3&#x2032;,4&#x2032;-benzophenone dianhydride (a-BTDA). First, a-BTDA is converted to its corresponding N-alkyl or N-phenyl bisimides by reacting with either methylamine or aniline. The sequential addition of two trifluoromethyl (CF) groups to the carbonyl unit of a-BTDA produce the corresponding bisimides of asymmetric 6FDA, which is hydrolyzed to the asymmetric 6F-tetracarboxylic acid followed by cyclodehydration to obtain asymmetric 6F-dianhydride (a-6FDA). Separately, the carbonyl unit of bisimides of a-BTDA is reduced to a methylene unit to afford the corresponding bisimides of asymmetric 3,4&#x2032;-(methylene)diphthalic anhydride, which is hydrolyzed to the asymmetric methylene tetracarboxylic acid followed by cyclodehydration to obtain 3,4&#x2032;-(methylene)diphthalic anhydride (a-MDPA).

Asymmetric dianhyrdrides and methods of making the same

This invention relates to the composition and processes for preparing thermoset polyimides derived from an asymmetric dianhydride, namely 2,3,3',4&#x2032;-benzophenone dianhydride (a-BTDA) with at least one diamine, and a monofunctional terminal endcaps. The monofunctional terminating groups include 4-phenylethynylphthalic anhydride ester-acid derivatives, phenylethyl trimellitic anhydride (PETA) and its ester derivatives as well as 3-phenylethynylaniline. The process of polyimide composite comprises impregnating monomer reactants of dianhydride or its ester-acid derivatives, diamine and with monofunctional reactive endcaps into glass, carbon, quartz or synthetic fibers and fabrics, and then stack up into laminates and subsequently heated to between 150-375&#xb0; C. either at atmosphere or under pressure to promote the curing and crosslinking of the reactive endcaps to form a network of thermoset polyimides.

Polyimides derived from novel asymmetric benzophenone dianhydrides

This invention relates to the composition and a solvent-free process for preparing novel imide oligomers and polymers specifically formulated with effective amounts of a dianhydride such as 2,3,3',4-biphenyltetra carboxylic dianydride (a-BPDA), at least one aromatic diamine and an endcapped of 4-phenylethynylphthalic anhydride (PEPA) or nadic anhydride to produce imide oligomers that possess a low-melt viscosity of 1-60 poise at 260-280&#xb0; C. When the imide oligomer melt is cured at about 371&#xb0; C. in a press or autoclave under 100-500 psi, the melt resulted in a thermoset polyimide having a glass transition temperature (T) equal to and above 310&#xb0; C. A novel feature of this process is that the monomers; namely the dianhydrides, diamines and the endcaps, are melt processable to form imide oligomers at temperatures ranging between 232-280&#xb0; C. (450-535&#xb0; F.) without any solvent. These low-melt imide oligomers can be easily processed by resin transfer molding (RTM), vacuum-assisted resin transfer molding (VARTM) or the resin infusion process with fiber preforms e.g. carbon, glass or quartz preforms to produce polyimide matrix composites with 288-343&#xb0; C. (550-650&#xb0; F.) high temperature performance capability.This invention relates to compositions and a solvent-free reaction process for preparing imide oligomers and polymers specifically derived from effective amounts of dianhydrides such as 2,3,3&#x2032;,4&#x2032;-biphenyltetracarboxylic dianhydride (a-BPDA), at least one aromatic polyamine and an end-cap such as 4-phenylethynyphthalic anhydride (PEPA) or nadic anhydride to produce imide oligomers that possess a low-melt viscosity of 1-60 poise at 260&#xb0; C.-280&#xb0; C.

Solvent free low-melt viscosity imide oligomers and thermosetting polymide composites

This invention relates to the compositions and processes for preparing thermoset and thermoplastic polyimides derived from novel asymmetrical dianhydrides: specifically 2,3,3',4&#x2032; benzophenone dianhydride (a-BTDA), and 3,4&#x2032;-(hexafluoroisopropylidene)diphthalic anhydride (a-6FDA). The a-BTDA anhydride is prepared by Suzuki coupling with catalysts from a mixed anhydride of 3,4-dimethylbenzoic acid or 2,3-dimethylbenzoic acid with 2,3-dimethylphenylboronic acid or 3,4-dimethylphenylboronic acid respectively, to form 2,3,3&#x2032;,4&#x2032;-tetramethylbenzophenone which is oxidized to form 2,3,3&#x2032;,4&#x2032;-benzophenonetetracarboxylic acid followed by cyclodehydration to obtain a-BTDA. The a-6FDA is prepared by nucleophilic triflouoromethylation of 2,3,3&#x2032;,4&#x2032;-tetramethylbenzophenone with trifluoromethyltrimethylsilane to form 3,4&#x2032;-(trifluoromethylmethanol)-bis(o-xylene) which is converted to 3,4&#x2032;-(hexafluoroisopropylidene-bis(o-xylene). The 3,4&#x2032;-(hexafluoroisopropylidene)-bis(o-xylene) is oxidized to the corresponding tetraacid followed by cyclodehydration to yield a-6FDA.

Polyimides derived from novel asymmetric dianhydrides

This invention relates to processes for preparing asymmetrical biphenyl tetracarboxylic acids and the corresponding asymmetrical dianhydrides, namely 2,3,3',4&#x2032;-biphenyl dianhydride (a-BPDA), 2,3,3&#x2032;,4&#x2032;-benzophenone dianhydride (a-BTDA) and 3,4&#x2032;-methylenediphthalic anhydride (-MDPA). By cross-coupling reactions of reactive metal substituted o-xylenes or by cross-coupling o-xylene derivatives in the presence of catalysts, this invention specifically produces asymmetrical biphenyl intermediates that are subsequently oxidized or hydrolyzed and oxidized to provide asymmetric biphenyl tetracarboxylic acids in comparatively high yields. These asymmetrical biphenyl tetracarboxylic acids are subsequently converted to the corresponding asymmetrical dianhydrides without contamination by symmetrical biphenyl dianhydrides.

Synthesis of asymmetric tetracarboxylic acids and corresponding dianhydrides

This invention relates to the compositions and processes for preparing 2,3,3',4&#x2032;-tetramethylbenzophenone and asymmetrical dianhydrides such as 2,3,3&#x2032;,4&#x2032; benzophenone dianhydride (a-BTDA), and 3,4&#x2032;-(hexafluoroisopropylidene)diphthalic anhydride (a-6FDA). a-BTDA is prepared by Suzuki coupling with catalysts from a mixed anhydride of 3,4-dimethylbenzoic acid and 2,3-dimethylbenzoic acid with a respective 2,3-dimethylphenylboronic acid and 3,4-dimethyl phenylboronic acid to form 2,3,3&#x2032;,4&#x2032;-tetramethylbenzophenone which is oxidized to 2,3,3&#x2032;,4&#x2032;-benzophenonetetracarboxylic acid followed by cyclodehydration to obtain a-BTDA. The a-6FDA was prepared by nucleophilic trifluoromethylation of 2,3,3&#x2032;,4&#x2032;-tetramethylbenzophenone with trifluoromethyltrimethylsilane to form 3,4&#x2032;-(trifluoromethylmethanol) bis(o-xylene) which is converted to 3,4&#x2032;-(hexafluoroisopropylidene-bis(o-xylene). The 3,4&#x2032;-(hexafluoroisopropylidene)-bis(o-xylene) is oxidized to the corresponding tetraacid followed by cyclodehydration to yield a-6FDA.

Synthesis of asymmetric tetracarboxylic acids and dianhydrides

This invention relates to the composition and a solvent-free process for preparing novel imide oligomers and polymers specifically formulated with effective amounts of a dianhydride such as 2,3,3',4-biphenyltetra carboxylic dianydride (a-BPDA), at least one aromatic diamine and an endcapped of 4-phenylethynylphthalic anhydride (PEPA) or nadic anhydride to produce imide oligomers that possess a low-melt viscosity of 1&#x2013;60 poise at 260&#x2013;280&#xb0; C. When the imide oligomer melt is cured at about 371&#xb0; C. in a press or autoclave under 100&#x2013;500 psi, the melt resulted in a thermoset polyimide having a glass transition temperature (T) equal to and above 310&#xb0; C. A novel feature of this process is that the monomers; namely the dianhydrides, diamines and the endcaps, are melt processable to form imide oligomers at temperatures ranging between 232&#x2013;280&#xb0; C. (450&#x2013;535&#xb0; F.) without any solvent. These low-melt imide oligomers can be easily processed by resin transfer molding (RTM), vacuum-assisted resin transfer molding (VARTM) or the resin infusion process with fiber preforms e.g. carbon, glass or quartz preforms to produce polyimide matrix composites with 288&#x2013;343&#xb0; C. (550&#x2013;650&#xb0; F.) high temperature performance capability.

Solvent free low-melt viscosity imide oligomers and thermosetting polyimide composites

This invention is a highly concentrated stable solution of polyimide precursors (monomers) having a solids content ranging from about 80 to 98 percent by weight in lower aliphatic alcohols i.e. methyl and/or ethyl alcohol. The concentrated polyimide precursor solution comprises effective amounts of at least one aromatic diamine, at least one aromatic dianhydride or a lower molecular weight alkyl ester of said dianhydride, and a monofunctional endcap including monoamines, monoanhydrides and the lower alkyl esters of said monoanhydrides. These concentrated polyimide precursor solutions are particularly useful for the preparation of fibrous prepregs and composites for use in structural materials for military and civil applications.

High-solids polyimide precursor solutions

Provided is a fabrication that is simple to make and cost effective in optimizing performance for moderately extended high velocity missions of high performance airborne vehicles. To counter rapid thermal loading while providing a relatively low cost structure, a laminate, in a preferred embodiment an intermediate modulus carbon fiber laminated as fabric layers in a resin matrix, is stitched through with glass fiber material. This laminate is then cured and formed as a section of skin of a supersonic missile, enabling extended supersonic operation, nominally some minutes after the laminate's T has been reached or exceeded. Additionally, an airframe and airframe members constructed in accordance with a preferred embodiment of the present invention are disclosed. Compared to existing materials, it reduces cost and weight, increases thermal stability, and maximizes internal payload.

Low cost structural fabrication that resists catastrophic failure under rapid thermal loading

This invention relates the novel diamines, the polyimide oligomers and the polyimides derived therefrom and to the method of preparing the diamines, oligomers and the polyimides. The thermoplastic polyimides derived from the aromatic diamines of this invention are characterized as having a high glass transition temperature, good mechanical properties and improved processability in the manufacture of adhesives, electronic and composite materials for use in the automotive and aerospace industry. The distinction of the novel aromatic diamines of this invention is the 2,2',6,6'-substituted biphenyl radicals which exhibit noncoplanar conformation that enhances the solubility of the diamine as well as the processability of the polyimides, while retaining a relatively high glass transition temperature and improved mechanical properties at useful temperature ranges.

Aromatic diamines and polyimides based on 4,4'-bis-(4-aminophenoxy)-2,2'

This invention relates the novel diamines, the polyimide oligomers and the polyimides derived therefrom and to the method of preparing the diamines, oligomers and the polyimides. The thermoplastic polyimides derived from the aromatic diamines of this invention are characterized as having a high glass transition temperature, good mechanical properties and improved processability in the manufacture of adhesives, electronic and composite materials for use in the automotive and aerospace industry. The distinction of the novel aromatic diamines of this invention is the 2,2',6,6'-substituted biphenyl radicals which exhibit noncoplanar conformation that enhances the solubility of the diamine as well as the processability of the polyimides, while retaining a realatively high glass transition temperature and improved mechanical properties at useful temperature ranges.

Polyimides based on 4,4'-bis (4-aminophenoxy)-2,2'or 2,2',

Addition polyimide resins having improved thermo-oxidative stability and enhanced processability are prepared by the reaction of a mixture of monomers comprising a non-planar polyphenyl diamine (a), a diester of tetracarboxylic acid or the corresponding dianhydride (b) and an end-capping agent (c), or a diamine (d), a non-planar polyphenyl diester or dianhydride of a tetracarboxylic acid (e) and an end-capping agent (c).

Growing community of inventors

Brecksville, OH, United States of America

Chun-Hua K Chuang