Process for preparing polyimides

Abstract

The invention relates to stoichiometric salts of tetracarboxylic acids and diamines of the general formula (I) wherein R1 is selected from the group consisting of tetravalent residues of butane, cyclobutane, cyclopentane, cyclohexane, tetrahydrofuran and benzophenone and R2 is selected from the group consisting of divalent residues of unbranched, branched or cyclic aliphatic hydrocarbons having 3 to 15 carbon atoms, with the proviso that the salts of the formula (I) are water-soluble and are selected from the group consisting of compounds (1) to (28); and to polyimides prepared from these salts by polycondensation.

Description

[0001] This invention relates to a novel method for preparing polyimide. Background Technology

[0002] Polyimides are valuable materials for a wide range of applications. They are typically synthesized by polycondensation of a diamine with a tetracarboxylic acid or its dianhydride in solution, in the molten state, or even in the solid state. A common method is to form a stoichiometric salt of the diamine and the tetracarboxylic acid or its dianhydride prior to polymerization. This is usually done by simply mixing the monomers in water and separating the water-insoluble and thus precipitated salt, as also described, for example, in WO 2016 / 032299 A1. The anhydride undergoes hydrolysis to form the free tetracarboxylic acid, in which each of the two carboxyl groups forms an ammonium salt with the amino group (Unterlass et al., “Mechanistic study of hydrothermal synthesis of aromatic polyimides”, Polym. Chem. 2011, 2, 1744). In the monomer salts obtained in this way, sometimes called “AH salts” (similar to the synthesis of polyamides and especially nylon), the two monomers are present in an exact 1:1 molar ratio, which is why subsequent polymerization produces extremely pure polyimides. The following is an example of the reaction process for two typical aromatic monomers:

[0003]

[0004] In recent years, it has been discovered that some diamine and tetracarboxylic acid monomer salts are water-soluble, which offers significant advantages in the manufacture of polyimides because it eliminates the need for organic solvents. For example, aqueous solutions of the salts can be used to coat surfaces, and the coating can then be dried by heating and simultaneously imidized, with water vapor as the only byproduct. However, corresponding disclosures for the preparation of water-soluble monomer salts are only found in a few patent documents, namely JP 2000 / 319389 A, JP 2002 / 121348 A, and JP 2013 / 256642 A, as well as the inventor's patent family based on AT 519.038.

[0005] Of all three Japanese patent applications cited above, only one monomer salt is actually produced and undergoes polyimide formation, namely, by benzophenone tetracarboxylic acid and m-xylenediamine:

[0006]

[0007] JP 2002 / 121348 A and, in particular, the earlier application JP 2000 / 319389 A from the same applicant, list other examples of diamines and tetracarboxylic acids whose combinations allegedly produce water-soluble monomeric salts. In the latter document, these primarily include (i.e., 35) aromatic diamines, but also include some (10) alicyclic diamines based on cyclohexyl residues, some (14) aliphatic diamines, and two polyether diamines. The tetracarboxylic acids listed as being compatible with the said diamines are also primarily (8) aromatic and several (3) alicyclic (cyclopropane, cyclopentane, and hexanetetracarboxylic acids), with butanetetracarboxylic acid being the only aliphatic representative. However, neither document examines nor demonstrates whether the monomeric salts to be prepared from their combinations are actually water-soluble.

[0008] In the earlier work of the inventors of this invention (the results of which are disclosed in the Austrian patent family AT 519.038 A1), the inventors developed several monomeric salts derived from combinations of m-xylenediamine and ethylenediamine with three tetracarboxylic acids, namely benzophenonetetracarboxylic acid, butanetetracarboxylic acid, and tetrahydrofurantetracarboxylic acid (and thus also including the aforementioned salts derived from benzophenonetetracarboxylic acid and m-xylenediamine) and confirmed their water solubility in each case. However, the inventors have also prepared a series of monomeric salts that have proven to be non-water-soluble.

[0009] In this context, the objective of the present invention is to provide other monomer salts that have been shown to be water-soluble and to treat their aqueous solutions to form polyimides. Summary of the Invention

[0010] In a first aspect, this invention achieves this objective by providing a stoichiometric salt of a tetracarboxylic acid and a diamine of the following general formula (I):

[0011]

[0012] Wherein R1 is selected from tetravalent residues of butane, cyclobutane, cyclopentane, cyclohexane, tetrahydrofuran, and benzophenone, and R2 is selected from divalent residues of straight-chain, branched, or cyclic aliphatic hydrocarbons having 3 to 15 carbon atoms, the stoichiometric salt of formula (I) is characterized by

[0013] i) It is water-soluble; and

[0014] ii) It is selected from the following compounds:

[0015] a) Salts of tetrahydrofuran-2,3,4,5-tetracarboxylic acid and aliphatic diamines

[0016] Propane-1,3-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (1),

[0017] Butane-1,4-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (2),

[0018] Pentane-1,5-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (3),

[0019] 2,2-Dimethylpropane-1,3-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (4),

[0020] Hexane-1,6-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (5),

[0021] 2-Methylpentane-1,5-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (6),

[0022] Heptane 1,7-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (7),

[0023] Octane-1,8-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (8),

[0024] Nonane-1,9-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (9);

[0025] b) Salts of tetrahydrofuran-2,3,4,5-tetracarboxylic acid and alicyclic diamines

[0026] Cyclohexane-1,2-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (10),

[0027] Cyclohexane-1,3-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (11),

[0028] Cyclohexane-1,4-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (12),

[0029] Cyclohexane-1,3-bis(methaneammonium)dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (13),

[0030] Cyclohexane-1,4-bis(methaneammonium)dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (14),

[0031] Norbornene-bis(methylammonium)dihydrotetrahydrofuran 2,3,4,5-tetracarboxylate (15),

[0032] Isophorone diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (16),

[0033] Three Rings [5.2.1.0] 2,6] Decane-3(4),8(9)-bis(methaneammonium)dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (17),

[0034] 4,4'-methylene-bis(2-methylcyclohexylammonium)dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (18);

[0035] c) Salts of 1,2,3,4-butanetetracarboxylic acid and alicyclic diamines

[0036] Norbornene-bis(methylammonium)dihydro-1,2,3,4-butanetetracarboxylate (19),

[0037] Three Rings [5.2.1.0] 2,6 ] Decane-3(4),8(9)-bis(methaneammonium)dihydro-1,2,3,4-butanetetracarboxylate (20);

[0038] d) Salts of 1,2,3,4-cyclobutanetetracarboxylic acid and alicyclic diamines

[0039] Norbornene-bis(methylammonium)dihydro-1,2,3,4-cyclobutanetetracarboxylate (21),

[0040] Three Rings [5.2.1.0] 2,6 ] Decane-3(4),8(9)-bis(methaneammonium)dihydro-1,2,3,4-cyclobutanetetracarboxylate (22);

[0041] e) Salts of 1,2,3,4-cyclopentanetetracarboxylic acid and alicyclic diamines

[0042] Norbornene-bis(methylammonium)dihydro-1,2,3,4-cyclopentanetetracarboxylate (23),

[0043] Three Rings [5.2.1.0] 2,6 ] Decane-3(4),8(9)-bis(methaneammonium)dihydro-1,2,3,4-cyclopentanetetracarboxylate (24);

[0044] f) Salts of 1,2,4,5-cyclohexanetetracarboxylic acid and alicyclic diamines

[0045] Norbornene-bis(methylammonium)dihydro-1,2,4,5-cyclohexanetetracarboxylate (25),

[0046] Three Rings [5.2.1.0] 2,6 ] Decane-3(4),8(9)-bis(methaneammonium)dihydro-1,2,4,5-cyclohexanetetracarboxylate (26); and

[0047] g) Salt of 3,3',4,4'-benzophenone tetracarboxylic acid and alicyclic diamine

[0048] Norbornene-bis(methylammonium)dihydro-3,3′,4,4′-benzophenone tetracarboxylate (27),

[0049] Three Rings [5.2.1.0] 2,6 ] Decane-3(4),8(9)-bis(methaneammonium)dihydro-3,3′,4,4′benzophenone tetracarboxylate (28).

[0050] All of these stoichiometric salts of formula (I) (1) to (28) have never been described in the literature and have not been proposed as a possible combination of tetracarboxylic acid and diamine, and they are all readily soluble in water.

[0051] A person skilled in the art might think that, given the prior art cited at the outset (in which many tetracarboxylic acid / diamine salt combinations are disclosed as water-soluble), it would be obvious to prepare salts from other combinations and examine their water solubility. However, in the course of their research, the inventors of this application also prepared many combinations from those disclosed as water-soluble in JP 2000 / 319389 A and found that most of the diamine and tetracarboxylic acid combinations listed there should not be water-soluble. More precisely, all the salts tested using at least one aromatic reactant were not water-soluble, even the salts from benzophenone tetracarboxylic acid and p-xylenediamine, although the salt of m-xylenediamine (which is the only salt actually prepared and tested in JP2000 / 319389 A) is indeed water-soluble, forming the basis of the aforementioned Japanese patent application, which is extremely unexpected. However, some salts of non-aromatic diamines or tetracarboxylic acids listed in JP 2000 / 319389 A are also insoluble in water, as specifically demonstrated in the following comparative examples. As a result, it can be assumed that of the more than 700 possible combinations produced by the acids and amines listed in JP 2000 / 319389 A, more than 600 are actually not water-soluble. Therefore, the fact that the vast majority of these combinations would prove to be water-soluble when other combinations are examined is extremely unexpected and entirely unpredictable to the inventors of the subject matter of this application.

[0052] In a preferred embodiment of the invention, the salt of formula (I) is selected from compounds (2), (3) and (5) to (9) above or from compounds (10) to (28) above for the reasons stated below, wherein the residue R2 of the alicyclic diammonium ion is present in each case as a mixture of multiple isomers.

[0053] On the one hand, these choices are based on the unexpected discovery that, in the case of aqueous solutions of salts derived from tetrahydrofuran-2,3,4,5-tetracarboxylic acid and aliphatic diamines, good film-forming properties were found only in the case of salts starting with a diamine chain length of 4 carbon atoms (i.e., 1,4-diaminobutane in compound (2)). In contrast, in the case of aqueous solutions of salts derived from tetrahydrofuran-2,3,4,5-tetracarboxylic acid and 1,3-diaminopropane (i.e., compound (1)) and salts derived from 2,2-dimethyldiaminopropane (i.e., compound (4)), as well as salts previously prepared by the inventors using ethylenediamine (see AT 519.038A1), each exhibited strong foaming properties, which resulted in the formation of bubbles when used as a surface coating.

[0054] Furthermore, it was unexpectedly discovered that if an aliphatic diamine has a chain length of more than 10 carbon atoms, it is no longer possible to obtain a water-soluble salt regardless of which tetracarboxylic acid is used.

[0055] Furthermore, on the other hand, in compounds (10) to (28), all are salts of alicyclic diamines and various acids, including benzophenone tetracarboxylic acid, wherein those salts in which alicyclic diamines exist as a mixture of multiple stereoisomers are preferred, as mentioned above. This is based on another unexpected discovery by the inventors that when a mixture of isomers is present, the salts have better solubility than when using alicyclic diamines in which only one stereoisomer is present. This is particularly evident because, in the two diamines 4,4'-methylene-bis(cyclohexylamine) and its dimethyl derivative 4,4'-methylene-bis(2-methylcyclohexylamine), when combined with three different tetracarboxylic acids (aromatic, alicyclic, and aliphatic), only the methylated derivative produces a water-soluble salt in all three cases, but the unmethylated diamine does not produce a water-soluble salt. However, since this is completely opposite to the water solubility of the two diamines, the presence of stereoisomers obviously improves the water solubility of stoichiometric salts.

[0056] All of this is explained and documented in more detail in the following examples and comparisons.

[0057] In a second aspect, the present invention also provides a method for preparing a salt according to formula (I) of the first aspect by mixing the corresponding tetracarboxylic acid or its dianhydride with the corresponding diamine in a solvent and subsequently separating the stoichiometric salt formed in this manner, the method being characterized in that...

[0058] Optionally, a tetracarboxylic acid or its dianhydride is dissolved under heating in an organic solvent that is a solvent for both reactants but not a solvent for the salt. A diamine is then added and the reaction mixture is stirred to form a stoichiometric salt, which is subsequently precipitated from the solution and separated.

[0059] Optionally, i.e. in the preferred embodiment,

[0060] Add an aliphatic diamine with a chain length of 4 to 9 carbon atoms; or

[0061] Alicyclic diamines are added in the form of a mixture of multiple isomers.

[0062] In contrast to the method disclosed in AT 519.038 A1, according to the present invention, the tetracarboxylic acid and diamine are not combined directly in water, which is the solvent for salt formation, but rather in an organic solvent capable of dissolving both reactants but not their salt. The advantage of this method is that the salt formed in this manner precipitates from the solution, while any impurities remain at least largely in the solution.

[0063] Polar solvents, especially protic polar solvents, are preferred for this purpose, and isopropanol is specifically used because it readily evaporates from the precipitated salt.

[0064] In a third aspect, the invention also provides the use of the salt of formula (I) according to the first aspect for the preparation of polyimides. For this purpose, in a preferred embodiment, the polyimide is prepared by subjecting an aqueous solution of the salt of formula (I) to a treatment step and subsequently heating it to induce polycondensation while simultaneously evaporating water. This provides the advantage that no organic solvents escape into the environment during the treatment and subsequent polycondensation.

[0065] In the processing steps, the aqueous salt solution is preferably formed into the desired shape or applied to a surface, followed by heating. In a preferred embodiment, the aqueous solution is formed into the desired shape by foaming, and it is possible to add a foaming agent and / or foam stabilizer as needed before foaming. For this purpose, one or more fatty acid dialkylolamides may be added.

[0066] Furthermore, in a final aspect, the present invention also relates to polyimides of general formula (II) prepared using salts of formula (I):

[0067]

[0068] Where R1 and R2 are as previously defined and n≥2, the resulting polyimide is characterized by being selected from the following:

[0069] a) Polyimides derived from tetrahydrofuran-2,3,4,5-tetracarboxylic acid and aliphatic diamines

[0070] Poly(N,N′-(1,3-propylidene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(101),

[0071] Poly(N,N′-(1,4-butylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(102),

[0072] Poly(N,N′-(1,5-pentylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(103),

[0073] Poly(N,N′-(2,2-dimethyl-1,3-propylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(104),

[0074] Poly(N,N′-(1,6-hexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(105),

[0075] Poly(N,N′-(2-methyl-1,5-pentylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(106),

[0076] Poly(N,N′-(1,7-heptanyl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(107),

[0077] Poly(N,N′-(1,8-octylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(108),

[0078] Poly(N,N′-(1,9-nonylidene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(109);

[0079] b) Polyimides derived from tetrahydrofuran-2,3,4,5-tetracarboxylic acid and alicyclic diamines

[0080] Poly(N,N′-(1,2-cyclohexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(110),

[0081] Poly(N,N′-(1,3-cyclohexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(111),

[0082] Poly(N,N′-(1,4-cyclohexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(112),

[0083] Poly(N,N′-(cyclohexane-1,3-dimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(113),

[0084] Poly(N,N′-(cyclohexane-1,4-dimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(114),

[0085] Poly(N,N′-(norbornenedimethyl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(115),

[0086] Poly(N,N′-(isophoryl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(116),

[0087] Poly(N,N′-(tricyclic [5.2.1.0]) 2.6 ]decane-3(4),8(9)-dimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(117,

[0088] Poly(N,N'-(4,4'-methylene-bis(2-methylcyclohexyl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(118);

[0089] c) Polyimides derived from 1,2,3,4-butanetetracarboxylic acid and alicyclic diamines

[0090] Poly(N,N′-(norbornenedimethyl)butane-1,2,3,4-tetracarboxylic acid diimide)(119),

[0091] Poly(N,N'-(tricyclic [5.2.1.0]) 2.6 ] Decane-3(4),8(9)-dimethylene)butane-1,2,3,4-tetracarboxylic acid diimide)(120);

[0092] d) Polyimides derived from 1,2,3,4-cyclobutanetetracarboxylic acid and alicyclic diamines

[0093] Poly(N,N′-(norbornenedimethyl)cyclobutane-1,2,3,4-tetracarboxylic acid diimide)(121),

[0094] Poly(N,N'-(tricyclic [5.2.1.0]) 2.6 ] Decane-3(4),8(9)-dimethylene)cyclobutane-1,2,3,4-tetracarboxylic acid diimide)(122);

[0095] e) Polyimides derived from 1,2,3,4-cyclopentanetetracarboxylic acid and alicyclic diamines

[0096] Poly(N,N′-(norbornenedimethyl)cyclopentane-1,2,3,4-tetracarboxylic acid diimide)(123),

[0097] Poly(N,N'-(tricyclic [5.2.1.0]) 2.6 ] Decane-3(4),8(9)-dimethylene)cyclopentane-1,2,3,4-tetracarboxylic acid diimide)(124);

[0098] f) Polyimides derived from 1,2,4,5-cyclohexanetetracarboxylic acid and alicyclic diamines

[0099] Poly(N,N′-(norbornenedimethyl)cyclohexane-1,2,4,5-tetracarboxylic acid diimide)(125),

[0100] Poly(N,N'-(tricyclic [5.2.1.0]) 2.6 ]decane-3(4),8(9)-dimethylene)cyclohexane-1,2,4,5-tetracarboxylic acid diimide)(126); and

[0101] g) Polyimide derived from 3,3',4,4'-benzophenone tetracarboxylic acid and alicyclic diamine

[0102] Poly(N,N′-(norbornenedimethyl)-3,3′,4,4′-benzophenone tetracarboxylic acid diimide)(127),

[0103] Poly(N,N′-(tricyclic [5.2.1.0]) 2.6 ] Decane-3(4),8(9)-dimethylene)-3,3′,4,4′-benzophenone tetracarboxylic acid diimide)(128.

[0104] Similar to the stoichiometric monomer salts of formula (I) used to prepare these polyimides, these polyimides are novel, can be prepared from aqueous solutions of salts in a simple, inexpensive and environmentally friendly manner, and have advantageous properties, such as high flexibility in terms of coatings made from them.

[0105] Example

[0106] The invention will now be described in more detail based on specific exemplary embodiments and comparative examples.

[0107] All reagents were purchased from commercial sources and used without further purification. IR spectra were obtained on a Tensor 27 using FT-IR ATRR spectroscopy. 1 H and 13 C-NMR spectra were recorded on Avance 250 or DRX-400FT spectrometers operating at 250 or 400 MHz, both from Bruker. TGA measurements were performed using a Perkin Elmer TGA 8000 thermogravimetric analyzer, and a Hettich ROTANTA 460R centrifuge was used to centrifuge the monomeric salt suspension.

[0108] Synthesis 1

[0109] General scheme for preparing monomeric salts of formula (I)

[0110]

[0111] In a 50 mL round-bottom flask equipped with a reflux condenser, approximately 0.7 mmol of the corresponding tetracarboxylic acid R1(COOH)4 was mixed with 50 mL of isopropanol and magnetically stirred, optionally heated to no more than 80 °C, until a clear solution was formed, and then cooled. Subsequently, an equimolar amount of the corresponding diamine H2N-R2-NH2 was added at room temperature as a solid, or in the case of a liquid diamine, using a micropipette, and the mixture was stirred for several hours under standard conditions. The resulting suspension of the stoichiometric salt of the precipitate was centrifuged at 11,500 rpm for several minutes, decanted, washed again with isopropanol, and centrifuged again at 11,500 rpm for several minutes. The liquid phase was then decanted, and the solid salt was dried to constant weight under high vacuum. The yield achieved was always quantitative.

[0112] Synthesis 2

[0113] General instructions for the preparation of polyimides of formula (II)

[0114]

[0115] In a glass beaker, a consistent, clear solution of approximately 40% by weight of the corresponding monomer salt of formula (I) was prepared in 1 ml of distilled water. These solutions were applied to a glass or aluminum surface using a Pasteurized pipette, and the surface was placed in a programmable oven at 50°C and subsequently subjected to a temperature program from 50°C to 250°C for 38–62 h to evaporate the water and ensure complete polycondensation into polyimide of formula (II). After the sample cooled, the resulting polyimide film was peeled off the surface and analyzed by FT-IRR-ATR and TGA.

[0116] Compare Examples 1 to 107 with Examples 1 to 28

[0117] Preparation and study of stoichiometric salts of formula (I)

[0118] As described above under “Synthesis 1”, the stoichiometric salts of formula (I) are prepared, and their solubility is tested by mixing 1 ml of distilled water with about 20 to 40% by weight of the corresponding salt and stirring for 15 minutes. Those salts that do not produce a clear solution and leave no significant precipitate as sediment are called “insoluble in water”.

[0119] For this purpose, the following tetracarboxylic acid is used:

[0120]

[0121] The diamine used is i) one of the following aliphatic diamines:

[0122]

[0123]

[0124] and ii) the following alicyclic diamines:

[0125]

[0126]

[0127] and iii) the following aromatic diamines:

[0128]

[0129] The solubility results obtained for examples (B1 to B28) and comparative examples (C1 to C107) are summarized in the table for the back leaf.

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136] A careful examination of the results in the table above reveals that of the 107 salts in the comparative examples, only 40 are insoluble in water, while 67 are soluble. Furthermore, of the 107 salts, only 15 cannot be derived from the two lists disclosed in JP 2000 / 319389 A, while 91 can be derived from them. Therefore, at first glance, most (though not all) salts that can be derived from the prior art appear to be actually soluble in water. However, this first impression is misleading for the following reasons.

[0137] Following the initial discovery that salts of tetrahydrofuran and butanetetracarboxylic acids were insoluble in water, specifically the salts of dodecane-1,12-diamine or 4,4'-methylenebis(cyclohexylamine), and conversely, only the corresponding salts of the aromatic diamine m-xylenediamine were water-soluble, while all other salts of aromatic diamines were not water-soluble. Previously, the preparation of salts of the three cycloaliphatic tetracarboxylic acids (tetracarboxylic acids of cyclobutane, pentane, and hexane) with other aromatic diamines to test their water solubility had been neglected.

[0138] For these three acids, only their salts with m-xylenediamine are confirmed to be soluble in water, as is known from the prior art for the other three acids, including their salts with benzophenone tetracarboxylic acid. This is the basis for the disclosures in the three Japanese patent applications cited above. On the other hand, those skilled in the art can reasonably assume that the combination of the three cyclic aliphatic tetracarboxylic acids with other aromatic diamines will not produce water-soluble salts, which is the subject of the experiments currently being conducted by the inventors. This will produce an additional 27 water-insoluble salts that are derived from JP 2000 / 319389 A, which will balance the above ratio of soluble to insoluble salts to 67:67.

[0139] Furthermore, JP 2000 / 319389 A lists a total of 61 aromatic and 26 non-aromatic diamines, as well as 8 aromatic and 4 non-aromatic tetracarboxylic acids. Based on the assumptions of the above results, the vast majority of the 628 derivatizable salts containing at least one aromatic component are insoluble in water, and the majority of the 104 derivatizable salts without aromatic components are actually water-soluble. All combinations derivatizable from JP 2000 / 319389 A end with a soluble salt to insoluble salt ratio of approximately 1:6.

[0140] This hypothesis is also supported by the fact that even the two aromatic diamines, namely diaminopyridine (pyridine-2,6-diamine) and diaminotriazole (1,2,4-triazole-3,5-diamine) (which are relatively water-soluble diamines) that are not disclosed in the prior art for the preparation of stoichiometric salts and were first used for this purpose by the inventors, do not produce water-soluble salts with any of the three tetracarboxylic acids tested.

[0141] However, even more surprisingly, some salts exhibit opposite solubility despite their strong structural similarity.

[0142] First, there is a striking comparison between m-xylenediamine and p-xylenediamine, where the former consistently produces water-soluble salts, while the latter does not form water-soluble salts in any combination with tetracarboxylic acids, even though both diamines are readily miscible with water. Judging from the above findings of the inventors, they themselves, in their early work and the inventors of the aforementioned Japanese applications, have conveniently chosen the aromatic diamine m-xylenediamine for their research on the formation of water-soluble stoichiometric salts with various tetracarboxylic acids, although this is not the case for all other aromatic diamines tested.

[0143] Equally surprising is the behavior of salts prepared from two diamines, 4,4′-methylene-bis(cyclohexylamine) and its dimethyl derivative 4,4′-methylene-bis(2-methylcyclohexylamine), in combination with three different tetracarboxylic acids (aromatic, alicyclic, and aliphatic). In all three cases, only the methylated derivative produced a water-soluble salt, while the unmethylated diamine did not. This contrasts sharply with the water solubility of diamines; Wikipedia lists the water solubility of 4,4′-methylene-bis(cyclohexylamine) as approximately 4 g / L, while the water solubility of the dimethylated derivative 4,4′-methylene-bis(2-methylcyclohexylamine) is only approximately 88 mg / L (according to http: / / www.perflavory.com / docs / doc1195061.html), which is 45 times lower. Not wishing to be bound by any particular theory, the inventors deduced that the presence of stereoisomers increases the water solubility of stoichiometric salts because it increases the likelihood of hydration of the molecule in an aqueous environment. In the case of the dimethyl derivatives above, the cis-trans isomers exist on both cyclohexyl rings, which is not the case with nonmethylated diamines.

[0144] Therefore, in preparing water-soluble stoichiometric salts, it is preferable to select a mixture of tetracarboxylic acids and / or diamines that have multiple stereoisomers, rather than pure isomers, for salt formation, and more preferably, to use both a mixture of acid isomers and a mixture of diamine isomers. This applies not only to alicyclic compounds, but especially to them.

[0145] For this reason, the inventors chose norbornene-bis(methylamine) and tricyclic [5.2.1.0] 2,6 Decane-3(4),8(9)-bis(methylamine) is a novel diamine, which is not described in the literature for the preparation of such stoichiometric salts, and it exists in a variety of stereoisomers, and it can also be commercially available as a mixture of isomers without the need for special synthesis.

[0146] Therefore, in compounds (10) to (28), that is, salts of the present invention of alicyclic diamines and various acids (including benzophenone tetracarboxylic acid), wherein those salts in which the alicyclic group exists in the form of a mixture of various stereoisomers are preferred.

[0147] However, in the above situation, those skilled in the art will know that for any new combination of diamine and tetracarboxylic acid, it is impossible to predict whether the stoichiometric salt formed therefrom will be water-soluble, because solubility obviously does not or only depends on whether the acid and amine are individually soluble in water or to what extent they are soluble.

[0148] Furthermore, when using aqueous solutions of stoichiometric monomer salts to generate surface coatings, better film-forming properties were observed when using salts of tetrahydrofuran-2,3,4,5-tetracarboxylic acid with aliphatic diamines (i.e., compounds (1) to (9)) starting with a diamine chain length of 4 carbon atoms (i.e., starting with 1,4-diaminobutane in compound (2)). Significant foaming occurred in aqueous solutions of salts of tetrahydrofuran-2,3,4,5-tetracarboxylic acid with 1,3-diaminopropane (i.e., compound (1)) and with 2,2-dimethyldiaminopropane (i.e., compound (4)), as well as salts previously prepared by the inventors using ethylenediamine (see AT 519.038A1), which resulted in the formation of bubbles when used as surface coatings. For this reason, those compounds (2), (3) and (5) to (9) that are salts of formula (I) and aliphatic diamines and have a straight chain length of diamine residue R2 with at least 4 carbon atoms, are preferred according to the present invention if used for the production of polyimide films.

[0149] While it will be readily understood that the use of the novel monomer salts of formula (I) according to the invention is not limited to the production of polyimide films, this still represents preferred embodiments of their possible uses. However, as an alternative, these salts can also be processed into polyimides in any other way, such as by molding or foaming and subsequent heating to induce their polycondensation. During foaming, a foaming agent and / or foam stabilizer may be added as needed; for this purpose, one or more fatty acid dialkylolamides may be used. However, the following will only describe polyimides formed by surface coating and subsequent heating.

[0150] The novel compounds (1) to (28) prepared according to “Synthesis 1” were characterized as previously described. Data are presented below, where “Tp” represents the polymerization temperature and “Td” represents the decomposition temperature of the monomer salt, each determined by TGA at a heating rate of 10 K / min.

[0151] Example 1

[0152] Propane 1,3-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (1)

[0153] Tp.: 172℃; Td.: -

[0154] IR (cm) -1 ):2969,2826,1721,1561.

[0155] 1 H-NMR(250MHz,D2O)δ:4.82(dd,J=3.8,1.7Hz,2H),3,47(dd,J=3.8,1.7Hz,2H),3.10(m,4H),2.07(m,2H).

[0156] 13 C-NMR(100MHz,D2O)δ:177.91,175.76,81.52,52.28,36.54,24.79.

[0157] Example 2

[0158] Butane-1,4-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (2)

[0159] Tp.: 149°C; Td.: 394°C

[0160] IR (cm) -1 ):2941,2933,1720,1568.

[0161] 1 H-NMR(250MHz,D2O)δ:4,83(dd,J=3,8,1,6Hz,2H),3,51(dd,J=3,8,1,6Hz,2H),3,03(t,J=7,3

[0162] Hz, 4H), 1.74 (t, J = 7.3 Hz, 4H).

[0163] 13 C-NMR(100MHz,D2O)δ:178.11,176.08,81.63,52.62,38.79,23.84.

[0164] Example 3

[0165] Pentane-1,5-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (3)

[0166] Tp.: 149℃; Td.: 396℃

[0167] IR (cm) -1 ):2937,2873,1720,1568.

[0168] 1 H-NMR (250MHz, D2O) δ: 4.82 (dd, J=3.8, 1.5Hz, 2H), 3.47 (dd, J=3.8, 1.5Hz, 2H), 3.00 (m, 4H), 1.69 (m, 4H), 1.46 (m, 2H).

[0169] 13C-NMR(100MHz,D2O)δ:177.92,175.59,81.56,52.28,39.12,26.21,22.63.

[0170] Example 4

[0171] 2,2-Dimethylpropane-1,3-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (4)

[0172] Tp.: 148℃; Td.: -

[0173] IR (cm) -1 ):2969,2899,1719,1571.

[0174] 1 H-NMR (250MHz, D2O) δ: 4.81 (m, 2H), 3.45 (dd, J = 4.0, 1.6Hz, 2H), 3.01 (s, 4H), 1.14 (s, 6H).

[0175] 13 C-NMR(100MHz,D2O)δ:177.93,175.81,81.51,52.33,46.65,32.31,21.29.

[0176] Example 5

[0177] Hexane-1,6-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (5)

[0178] Tp.: 156℃; Td.: 444℃

[0179] IR (cm) -1 ):2934,2864,1716,1568.

[0180] 1 H-NMR (250MHz, D2O) δ: 4.83 (m, 2H), 3.47 (dd, J = 3.9, 1.5Hz, 2H), 2.99 (m, 4H), 1.70 (m, 4H), 1.41 (m, 4H).

[0181] 13 C-NMR(100MHz,D2O)δ:177.77,175.24,81.49,52.00,39.31,26.46,25.07.

[0182] Example 6

[0183] 2-Methylpentane-1,5-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (6)

[0185] Tp.: 142℃; Td.: 441℃

[0186] IR (cm) -1 ):2965,2934,1720,1568.

[0187] 1 H-NMR(400MHz,D2O)δ:4.83(dd,J=3.9,1.5Hz,2H),3.50(dd,J=3.9,1.5Hz,2H),3.0(m,3H ),2.82(m,1H),1.86(m,1H),1.70(m,2H),1.47(m,1H),1.29(m,1H),1.00(d,J=6.8Hz,3H).

[0188] 13 C-NMR(100MHz,D2O)δ:177.75,175.24,81.48,51.99,44.76,39.37,30.66,29.92,23.67,15.79.

[0189] Example 7

[0190] Heptane-1,7-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (7)

[0191] Tp.: 151℃; Td.: 442℃

[0192] IR (cm) -1 ):2932,2861,1722,1572.

[0193] 1 H-NMR (250MHz, D2O) δ: 4.84 (m, 2H), 3.50 (dd, J = 3.9, 1.5Hz, 2H), 2.98 (t, J = 7.6Hz, 4H), 1.65 (m, 4H), 1.37 (m, 6H).

[0194] 13 C-NMR(100MHz,D2O)δ:177.69,175.13,81.45,51.92,39.41,27.63,26.56,25.32.

[0195] Example 8

[0196] Octane-1,8-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (8)

[0197] Tp.: 145℃; Td.: 444℃

[0198] IR (cm) -1 ):2931,2859,1723,1574.

[0199] 1 H-NMR (250MHz, D2O) δ: 4.83 (m, 2H), 3.49 (dd, J = 3.9, 1.5Hz, 2H), 2.98 (t, J = 7.5Hz, 4H), 1.63 (m, 4H), 1.36 (m, 8H).

[0200] 13 C-NMR(100MHz,D2O)δ:177.80,175.27,81.51,52.05,39.46,27.92,26.64,25.44.

[0201] Example 9

[0202] Nonane-1,9-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (9)

[0203] Tp.: 147℃; Td.: 444℃

[0204] IR (cm) -1 ):2928,2857,1720,1572.

[0205] 1 H-NMR (250MHz, D2O) δ: 4.84 (dd, J=3.9, 1.5Hz, 2H), 3.50 (dd, J=3.9, 1.5Hz, 2H), 2.98 (t, J=7.5

[0206] Hz,4H),1.65(m,4H),1.33(m,10H).

[0207] 13 C-NMR(100MHz,D2O)δ:177.77,175.21,81.50,52.00,39.48,28.22,28.05,26.67,25.50.

[0208] Example 10

[0209] Cyclohexane-1,2-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (10)

[0210] Tp.: 172℃; Td.: 378℃

[0211] IR (cm) -1 ):2941,2872,1720,1558.

[0212] C-NM(100MHz,D2O)δ:177.71,175.60,81.33,52.07,52.01,49.77,29.28,25.69,22.73,20.15.

[0213] Example 11

[0214] Cyclohexane-1,3-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (11)

[0215] Tp.: 174℃; Td.: 380℃

[0216] IR (cm) -1 ):2969,2876,1721,1573.

[0217] 13 C-NMR(100MHz,D2O)δ:177.74,175.35,81.45,52.02,48.09,45.87,33.92,31.58,28.65,27.57,23.68,21.03,17.56.[ 13 C-NMR signals were determined using the APT method.

[0218] Example 12

[0219] Cyclohexane-1,4-diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (12)

[0220] Tp.: 196℃; Td.: 380℃

[0221] IR (cm) -1 ):2938,2874,1717,1566.

[0222] 13 C-NMR(100MHz,D2O)δ:178.34,176.97,81.80,53.35,48.42,46.98,27.98,23.69.

[0223] Example 13

[0224] Cyclohexane-1,3-bis(methaneammonium)dihydro-tetrahydrofuran-2,3,4,5-tetracarboxylate (13)

[0225] Tp.: 152℃; Td.: 451℃

[0226] IR (cm) -1 ):2926,2859,1720,1571.

[0227] 13 C-NMR(100MHz,D2O)δ:177.77,175.31,81.48,52.06,44.85,42.81,34.86,32.96,30.87,30.45,28.89,27.62,24.08,19.20.[ 13 C-NMR signals were determined using the APT method.

[0228] Example 14

[0229] Cyclohexane-1,4-bis(methaneammonium)dihydro-tetrahydrofuran-2,3,4,5-tetracarboxylate (14)

[0230] Tp.: 153℃; Td.: 454℃

[0231] IR (cm) -1 ):2925,2862,1720,1572.

[0232] 13 C-NMR(100MHz,D2O)δ:177.88,175.48,81.54,52.21,44.83,42.56,34.95,32.89,28.57,23.67.

[0233] Example 15

[0234] Norbornene-bis(methylammonium)dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (15)

[0235] Tp.: 160℃; Td.: 426℃

[0236] IR (cm) -1 ):2952,2875,1720,1569.

[0237] Example 16

[0238] Isophorone diammonium dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (16)

[0239] Tp.: 163℃; Td.: 389℃

[0240] IR (cm) -1):2958,2624,1718,1569.

[0241] 13 C-NMR(100MHz,D2O)δ:178.05,175.94,81.61,52.74,52.55,45.19,45.04,42.32,38.31,33.78,33.75,30.83,26.35,21.59.[ 13 C-NMR signals were determined using the APT method.

[0242] Example 17

[0243] Three Rings [5.2.1.0] 2,6 ] Decane-3(4),8(9)-bis(methaneammonium)dihydro-tetrahydrofuran-2,3,4,5-tetracarboxylate (17)

[0244] Tp.: 151℃; Td.: 433℃

[0245] IR (cm) -1 ):2944,2875,1718,1577.

[0246] Example 18

[0247] 4,4′-Methylene-bis(2-methylcyclohexylammonium)dihydrotetrahydrofuran-2,3,4,5-tetracarboxylate (18)

[0248] Tp.: 170℃; Td.: 409℃

[0249] IR (cm) -1 ):2962,2923,1720,1571.

[0250] Example 19

[0251] Norbornene-bis(methylammonium)dihydro-1,2,3,4-butanetetracarboxylate (19)

[0252] Tp.: 192℃; Td.: 430℃

[0253] IR (cm) -1 ):2949,2871,1621,1548.

[0254] Example 20

[0255] Three Rings [5.2.1.0] 2,6 ] Decane-3(4),8(9)-bis(methaneammonium)dihydro-1,2,3,4-butanetetracarboxylate (20)

[0256] Tp.: 163℃; Td.: 369℃

[0257] IR (cm) -1 ):2947,2869,1622,1548.

[0258] 13 C-NMR(100MHz,D2O)δ:181.16,180.09,52.64,47.81,45.19,45.01,42.32,38.70,38.24,33.75,30.82,27.51,26.37,25.96,21.61.[ 13 C-NMR signals were determined using the APT method.

[0259] Example 21

[0260] Norbornene-bis(methylammonium)dihydro-1,2,3,4-cyclobutanetetracarboxylate (21)

[0261] IR (cm) -1 ):2947,2869,1718,1548.

[0262] Example 22

[0263] Three Rings [5.2.1.0] 2,6 Decane-3(4),8(9)-bis(methaneammonium)dihydro-1,2,3,4-cyclobutanetetracarboxylate (22)

[0264] IR (cm) -1 ):2938,2871,1721,1545.

[0265] Example 23

[0266] Norbornene-bis(methylammonium)dihydro-1,2,3,4-cyclopentanetetracarboxylate (23)

[0267] Tp.: 154℃; Td.: 467℃

[0268] IR (cm) -1 ):2948,2871,1687,1560.

[0269] Example 24

[0270] Three Rings [5.2.1.0] 2,6 Decane-3(4),8(9)-bis(methaneammonium)dihydro-1,2,3,4-cyclopentanetetracarboxylate (24)

[0271] Tp.: 154℃; Td.: 444℃

[0272] IR (cm) -1 ):2943,2877,1686,1557.

[0273] Example 25

[0274] Norbornene-bis(methylammonium)dihydro-1,2,4,5-cyclohexanetetracarboxylate (25)

[0275] IR (cm) -1 ):2947,2870,1538.

[0276] Example 26

[0277] Three Rings [5.2.1.0] 2,6 ] Decane-3(4),8(9)-bis(methaneammonium)dihydro-1,2,4,5-cyclohexanetetracarboxylate (26)

[0278] Tp.: 168℃; Td.: 458℃

[0279] IR (cm) -1 ):2943,2873,1549.

[0280] Example 27

[0281] norbornene-bis(methylammonium)dihydro3,3′,4,4′-benzophenone tetracarboxylate (27)

[0283] IR (cm) -1 ):2947,2871,1720,1556.

[0284] Example 28

[0285] Three Rings [5.2.1.0] 2,6 Decane-3(4),8(9)-bis(methaneammonium)dihydro-3,3′,4,4′-benzophenone tetracarboxylate (28)

[0286] Tp.: 183℃; Td.: 455℃

[0287] IR (cm) -1 ):2948,2876,1717,1652,1555.

[0288] Examples 29 to 56

[0289] Preparation of polyimide

[0290] As described in “Synthesis 2” above, membranes of the present invention are prepared from 28 novel stoichiometric salts of the following polyimides, which are characterized as previously described.

[0291] Example 29

[0292] Poly(N,N′-(1,3-propylidene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(101)

[0293] IR (cm) -1 ):2973,2890,1772,1703,1345.

[0294] Example 30

[0295] Poly(N,N′-(1,4-butylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(102)

[0296] Td.: 392℃

[0297] IR (cm) -1 ):2941,2871,1770,1690,1353.

[0298] Example 31

[0299] Poly(N,N′-(1,5-pentylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(103)

[0300] Td.: 395℃

[0301] IR (cm) -1 ):2940,2864,1780,1748,1686,1336.

[0302] Example 32

[0303] Poly(N,N′-(2,2-dimethyl-1,3-propylidene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(104)

[0304] IR (cm) -1 ):2968,2937,1771,1707,1334.

[0305] Example 33

[0306] Poly(N,N′-(1,6-hexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(105)

[0307] Td.: 419℃

[0308] IR (cm) -1 ):2935,2862,1782,1748,1686,1342.

[0309] Example 34

[0310] Poly(N,N′-(2-methyl-1,5-pentylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(106)

[0311] Td.: 405℃

[0312] IR (cm) -1 ):2959,2875,1785,1750,1686,1334.

[0313] Example 35

[0314] Poly(N,N′-(1,7-heptanyl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(107)

[0315] Td.: 410℃

[0316] IR (cm) -1 ):2932,2858,1785,1749,1685,1342.

[0317] Example 36

[0318] Poly(N,N′-(1,8-octylyl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(108)

[0319] Td.: 414℃

[0320] IR (cm) -1 ):2929,2855,1781,1746,1685,1344.

[0321] Example 37

[0322] Poly(N,N′-(1,9-nonylidene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(109)

[0323] Td.: 413℃

[0324] IR (cm) -1 ):2929,2857,1782,1749,1686,1340.

[0325] Example 38

[0326] Poly(N,N′-(1,2-cyclohexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(110)

[0327] Td.: 378℃

[0328] IR (cm) -1 ):2936,2862,1780,1706,1376.

[0329] Example 39

[0330] Poly(N,N′-(1,3-cyclohexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(111)

[0331] Td.: 380℃

[0332] IR (cm) -1 ):2938,2865,1778,1701,1365.

[0333] Example 40

[0334] Poly(N,N′-(1,4-cyclohexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(112)

[0335] Td.: 380℃

[0336] IR (cm) -1 ):2934,2865,1778,1697,1370.

[0337] Example 41

[0338] Poly(N,N′-(cyclohexane-1,3-dimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(113)

[0339] Td.: 438℃

[0340] IR (cm) -1 ):2925,2853,1782,1750,1690,1333.

[0341] Example 42

[0342] Poly(N,N′-(cyclohexane-1,4-dimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(114)

[0343] Td.: 415℃

[0344] IR (cm)-1 ):2923,2855,1771,1687,1353.

[0345] Example 43

[0346] Poly(N,N′-(norbornenedimethyl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(115)

[0347] Td.: 415℃

[0348] IR (cm) -1 ):2948,2872,1781,1747,1691,1334.

[0349] Example 44

[0350] Poly(N,N′-(isophoryl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(116)

[0351] Td.: 388℃

[0352] IR (cm) -1 ):2953,2872,1775,1698,1353.

[0353] Example 45

[0354] Poly(N,N′-(tricyclic [5.2.1.0]) 2,6 ] Decane-3(4),8(9)-dimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(117)

[0355] Td.: 437℃

[0356] IR (cm) -1 ):2946,2875,1780,1691,1355.

[0357] Example 46

[0358] Poly(N,N′-(4,4′-methylene-bis(2-methylcyclohexyl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide)(118)

[0359] Td.: 380℃

[0360] IR (cm) -1 ):2954,2922,1771,1770,1356.

[0361] Example 47

[0362] Poly(N,N′-(norbornenedimethyl)butane-1,2,3,4-tetracarboxylic acid diimide)(119)

[0363] Td.: 461℃

[0364] IR (cm) -1 ):2941,2866,1773,1692,1340.

[0365] Example 48

[0366] Poly(N,N′-(tricyclic [5.2.1.0]) 2,6 ] Decane-3(4),8(9)-dimethylene)butane-1,2,3,4-tetracarboxylic acid diimide)(120)

[0367] Td.: 375℃

[0368] IR (cm) -1 ):2952,2874,1776,1695,1365.

[0369] Example 49

[0370] Poly(N,N′-(norbornenedimethyl)cyclobutane-1,2,3,4-tetracarboxylic acid diimide)(121)

[0371] IR (cm) -1 ):2947,2872,1772,1695,1338.

[0372] Example 50

[0373] Poly(N,N′-(tricyclic [5.2.1.0]) 2,6 ] Decane-3(4),8(9)-dimethylene)cyclobutane-1,2,3,4-tetracarboxylic acid diimide)(122)

[0374] IR (cm) -1 ):2942,2874,1771,1697,1338.

[0375] Example 51

[0376] Poly(N,N′-(norbornenedimethyl)cyclopentane-1,2,3,4-tetracarboxylic acid diimide)(123)

[0377] Td.: 444℃

[0378] IR (cm) -1 ):2943,2870,1774,1692,1343.

[0379] Example 52

[0380] Poly(N,N′-(tricyclic [5.2.1.0]) 2,6 ] Decane-3(4),8(9)-dimethylene)cyclopentane-1,2,3,4-tetracarboxylic acid diimide)(124)

[0381] Td.: 444℃

[0382] IR (cm) -1 ):2938,2874,1775,1694,1349.

[0383] Example 53

[0384] Poly(N,N′-(norbornenedimethyl)cyclohexane-1,2,4,5-tetracarboxylic acid diimide)(125)

[0385] IR (cm) -1 ):2945,2871,1771,1694,1340.

[0386] Example 54

[0387] Poly(N,N′-(tricyclic [5.2.1.0]) 2,6 ] Decane-3(4),8(9)-dimethylene)cyclohexane-1,2,4,5-tetracarboxylic acid diimide)(126)

[0388] Td.: 458℃

[0389] IR (cm) -1 ):2936,2871,1771,1693,1342.

[0390] Example 55

[0391] Poly(N,N′-(norbornenedimethyl)-3,3′,4,4′-benzophenone tetracarboxylic acid diimide)(127)

[0392] IR (cm) -1 ):2946,2871,1772,1702,1341.

[0393] Example 56

[0394] Poly(N,N′-(tricyclic [5.2.1.0]) 2,6 ] Decane-3(4),8(9)-dimethylene)-3,3′,4,4′-benzophenone tetracarboxylic acid diimide)(128)

[0395] Td.: 455℃

[0396] IR (cm) -1 ):2943,2871,1773,1704,1347.

[0397] Therefore, the present invention provides a series of novel stoichiometric salts of tetracarboxylic acids and diamines, all of which are readily soluble in water and highly suitable for the preparation of polyimides, as demonstrated by providing the corresponding polyimides.

Claims

1. A stoichiometric salt of a tetracarboxylic acid of the general formula (I) with a diamine: ###0001### (I) wherein R1 is selected from the group consisting of tetravalent residues of butane, cyclobutane, cyclopentane, cyclohexane, tetrahydrofuran and benzophenone and R2 is selected from the group consisting of divalent residues of linear, branched or cyclic aliphatic hydrocarbons having 3 to 15 carbon atoms, characterized in that i) the salt of formula (I) is water-soluble; and ii) it is selected from the group consisting of the following compounds: a) salts of tetrahydrofuran-2,3,4,5-tetracarboxylic acid with aliphatic diamines butane-1,4-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (2), pentane-1,5-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (3), 2,2-dimethylpropane-1,3-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (4), hexane-1,6-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (5), 2-methylpentane 1,5-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (6), heptane 1,7-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (7), octane-1,8-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (8), nonane-1,9-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (9); b) salts of tetrahydrofuran-2,3,4,5-tetracarboxylic acid with cycloaliphatic diamines cyclohexane-1,2-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (10), cyclohexane-1,3-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (1 1 ), cyclohexane-1,4-diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (12), cyclohexane-1,3-bis(methanammonium) dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (13), cyclohexane-1,4-bis(methanammonium) dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (14), norbornane-bis(methylammonium) dihydrogen tetrahydrofuran 2,3,4,5-tetracarboxylate (15), isophorone diammonium dihydrogen tetrahydrofuran-2,3,4,5-tetracarboxylate (16), c) salts of 1,2,3,4-butane tetracarboxylic acid with cycloaliphatic diamines norbornane-bis(methylammonium) dihydrogen-1,2,3,4-butane tetracarboxylate (19), d) salts of 1,2,3,4-cyclobutane tetracarboxylic acid with cycloaliphatic diamines norbornane-bis(methylammonium) dihydrogen-1,2,3,4-cyclobutane tetracarboxylate (21 ), e) salts of 1,2,3,4-cyclopentane tetracarboxylic acid with cycloaliphatic diamines norbornane-bis(methylammonium) dihydrogen-1,2,3,4-cyclopentane tetracarboxylate (23), f) salts of 1,2,4,5-cyclohexane tetracarboxylic acid with cycloaliphatic diamines norbornane-bis(methylammonium) dihydrogen-1,2,4,5-cyclohexane tetracarboxylate (25), g) salts of 3,3',4,4'-benzophenone tetracarboxylic acid with cycloaliphatic diamines. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-bis(methaneammonium) dihydro tetrahydrofuran-2,3,4,5-tetracarboxylate (17), 4,4 ' - methylene-bis(2-methylcyclohexylammonium) dihydro-tetrahydro- furan-2,3,4,5-tetracarboxylate (18); ​ ​ tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-bis(methaneammonium) dihydro-1,2,3,4-butanetetracarboxylate (20); ​ ​ tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-bis(methaneammonium) dihydro-1,2,3,4-cyclobutane tetracarboxylate (22); ​ ​ tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-bis(methaneammonium) dihydro-1,2,3,4-cyclopentane tetracarboxylate (24); ​ ​ tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-bis(methaneammonium) dihydro-1,2,4,5-cyclohexanetetracarboxylate (26); and ​ norbornane-bis(methylammonium) dihydro-3,3 ' ,4,4 ' -benzophenonetetracarboxylate (27), tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-bis(methaneammonium) dihydro-3,3 ' ,4,4 ' benzophenonetetracarboxylate (28).

2. The salt of formula (I) according to claim 1, characterized in that The salt is selected from the above compounds (2), (3) and (5) to (9); or the salt is selected from the above compounds (10) to (28), wherein the residue R2 of the cycloaliphatic diammonium ion is in each case a mixture of isomers.

3. A process for the preparation of a salt of formula (I) according to claim 1 or 2 by mixing the corresponding tetracarboxylic acid or its dianhydride with the corresponding diamine in a solvent and subsequently isolating the stoichiometric salt formed in this way, characterized in that The tetracarboxylic acid or its dianhydride is optionally dissolved, optionally under heating, in an organic solvent which is a solvent for both reactants but a non-solvent for the salt, followed by adding the diamine and stirring the reaction mixture to form the stoichiometric salt, which is then precipitated from solution and isolated, wherein optionally an aliphatic diamine having a chain length of 4 to 9 carbon atoms is added; or a cycloaliphatic diamine is added in the form of a mixture of isomers.

4. The method of claim 3, wherein The solvent is a protic polar solvent.

5. The method of claim 4, wherein The solvent is isopropanol.

6. Use of a salt of formula (I) according to claim 1 or 2 for the preparation of a polyimide.

7. Use according to claim 6, characterized in that The polyimide is prepared by subjecting an aqueous solution of the salt of formula (I) to a treatment step and subsequently heating to induce polycondensation while evaporating water.

8. Use according to claim 7, characterized in that The aqueous solution of the salt is shaped into a desired shape or applied to a surface in the treatment step, followed by heating.

9. Use according to claim 8, characterized in that The aqueous solution of the salt is shaped into a desired shape by foaming, wherein a foaming agent and / or a foam stabilizer is optionally added to the aqueous solution of the salt, followed by foaming.

10. Use according to claim 9, characterized in that At least one fatty acid dialkanolamide is added as a foam stabilizer.

11. Use according to claim 6, characterized in that The polyimide is a polyimide of general formula (II): wherein R1 and R2 are as defined previously and n > 2, characterized in that the polyimide is selected from the following: a) polyimides from tetrahydrofuran-2,3,4,5-tetracarboxylic acid and aliphatic diamines Poly(N,N ' - (1,4-Butylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (102), Poly(N,N ' - (1,5-pentylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (103), Poly(N,N ' - (2,2-dimethyl-1,3-propylen)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (104), Poly(N,N ' - (1,6-hexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (105), Poly(N,N ' - (2-methyl-1,5-pentylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (106), Poly(N,N ' - (1,7-heptamethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (107), Poly(N,N ' - (1,8-octylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (108), Poly(N,N ' - (1,9-butyleneglycol)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (109); b) polyimides from tetrahydrofuran-2,3,4,5-tetracarboxylic acid and cycloaliphatic diamines Poly(N,N ' - (1,2-cyclohexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (110), Poly(N,N ' - (1,3-cyclohexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (111), Poly(N,N ' - (1,4-cyclohexylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (112), Poly(N,N ' - (cyclohexane-1,3-dimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (113), Poly(N,N ' - (cyclohexane-1,4-dimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (114), Poly(N,N ' - (norbornanedimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (115), Poly(N,N ' - (isophrone)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (116), Poly(N,N ' -(tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-dimethylene)tetrahydrofuran-2,3,4,5-tetracarboxylic diimide) (117), Poly(N,N'-(4,4'-methylene-bis(2-methylcyclohexyl)tetrahydrofuran-2,3,4,5-tetracarboxylic acid diimide) (118); c) polyimides from 1,2,3,4-butanetetracarboxylic acid and cycloaliphatic diamines Poly(N,N ' - (Norbornanedimethylene)butane-1,2,3,4-tetracarboxylic diimide) (119), Poly(N,N'-(tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-dimethylene)butane-1,2,3,4-tetracarboxylic diimide) (120); d) polyimides from 1,2,3,4-cyclobutanetetracarboxylic acid and cycloaliphatic diamines Poly(N,N ' - (Norbornanedimethylene)cyclobutane-1,2,3,4-tetracarboxylic diimide) (121), Poly(N,N'-(tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-dimethylene)cyclobutane-1,2,3,4-tetracarboxylic diimide) (122); e) polyimides from 1,2,3,4-cyclopentanetetracarboxylic acid and cycloaliphatic diamines Poly(N,N ' - (Bicyclo[2.2.1]hept-5-ene-2,3:5,6-tetra-carboxylic acid diimide) (123), Poly(N,N'-(tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-dimethylene)cyclopentane-1,2,3,4-tetracarboxylic diimide) (124); f) polyimides from 1,2,4,5-cyclohexanetetracarboxylic acid and cycloaliphatic diamines Poly(N,N ' - (Norbornanedimethylene)cyclohexane-1,2,4,5-tetracarboxylic diimide) (125), Poly(N,N'-(tricyclo[5.2.1.0 2,6 ]decane-3(4),8(9)-dimethylene)cyclohexane-1,2,4,5-tetracarboxylic diimide) (126); and g) polyimides from 3,3',4,4'-benzophenonetetracarboxylic acid and cycloaliphatic diamines Poly(N,N ' -(norbornanedimethylene)-3,3 ' ,4,4 ' -benzophenonetetracarboxylic diimide) (127).

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