THERMOPLASTIC COPOLYIMIDES

Abstract

The present invention relates to semiaromatic semicrystalline thermoplastic copolyimides obtained by polymerization of at least: (a) an aromatic compound comprising two anhydride functions and/or carboxylic acid and/or ester derivatives thereof; (b) a diamine of formula (I) NH2RNH2 in which R is a divalent aliphatic hydrocarbon-based radical optionally comprising heteroatoms, the two amine functions being separated by a number X of carbon atoms, X being between 4 and 12; and (c) a diamine of formula (II) NH2RNH2 in which R is a divalent aliphatic hydrocarbon-based radical optionally comprising heteroatoms, the two amine functions being separated by a number Y of carbon atoms, Y being between 10 and 20; it being understood that diamine (b) is different from diamine (c).

Claims

1-18. (canceled)

19. A semiaromatic semicrystalline thermoplastic copolyimide obtained by polymerization of at least: (a) an aromatic compound comprising two anhydride functions and/or carboxylic acid and/or ester derivatives thereof; (b) a diamine of formula (I) NH2RNH2 selected from the group consisting of: 1,4-diaminobutane, 1,5-diaminopentane, 2-methyl-1,5-diaminopentane, hexamethylenediamine, 3-methylhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,2,4- and 2,4,4-trimethyl-hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane; and (c) a diamine of formula (II) NH2RNH2 in which R is a saturated or unsaturated, linear or branched, divalent aliphatic hydrocarbon-based radical, optionally comprising heteroatoms, wherein the two amine functions are separated by a number Y of carbon atoms, Y is between 10 and 20, and the radical R comprises not more than 20 carbon atoms; wherein the copolyimide has at least two melting points Tf, and the melting points are between 50 C. and 330 C., measured by differential scanning calorimetry and heating the copolyimide from 20 C. at a rate of 10 C./minute.

20. The copolyimide as claimed in claim 19, wherein the copolyimide is obtained with addition of chain limiter(s) and/or supplemented with an excess of one of the monomers, so as to create a stoichiometric imbalance.

21. The copolyimide as claimed in claim 19, wherein the copolyimide has two melting points Tf between 50 C. and 330 C., measured by differential scanning calorimetry and heating the copolyimide from 20 C. at a rate of 10 C./minute.

22. The copolyimide as claimed in claim 19, wherein the copolyimide has a glass transition temperature Tg of between 50 C. and +170 C.

23. The copolyimide as claimed in claim 19, wherein the aromatic compound comprising two anhydride functions is selected from the group consisting of: pyromellitic anhydride, 3,3,4,4-biphenyltetracarboxylic dianhydride, 2,3,3,4-biphenyltetracarboxylic dianhydride, 2,2,3,3-biphenyltetracarboxylic dianhydride, 3,3,4,4-benzophenonetetracarboxylic dianhydride, 2,2,3,3-benzophenonetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride and 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropanetetracarboxylic dianhydride.

24. The copolyimide as claimed in claim 19, wherein the aromatic compound comprising carboxylic acid functions derived from the two anhydride functions is selected from the group consisting of: pyromellitic acid, 3,3,4,4-biphenyltetracarboxylic acid, 2,3,3,4-biphenyltetracarboxylic acid, 2,2,3,3-biphenyltetracarboxylic acid, 3,3,4,4-benzophenonetetracarboxylic acid, 2,2,3,3-benzophenonetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 2,3,5,6-pyridinetetracarboxylic acid, 3,4,9,10-perylenetetracarboxylic acid, 3,3,4,4-tetraphenylsilanetetracarboxylic acid, 2,2-bis(3,4-bicarboxyphenyl)hexafluoropropanetetracarboxylic acid.

25. The copolyimide as claimed in claim 19, wherein the diamine (b) is selected from the group consisting of: 1,4-diaminobutane, 1,5-diaminopentane, 2-methyl-1,5-diaminopentane, and hexamethylenediamine.

26. The copolyimide as claimed in claim 19, wherein the diamine (c) is selected from the group consisting of: 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,13-diaminotridecane, 1,14-diaminotetradecane, 1,15-diaminopentadecane, 1,16-diaminohexadecane, 1,17-diaminoheptadecane, 1,18-diaminooctodecane, 1,19-diaminononadecane and 1,20-diaminoeicosane.

27. The copolyimide as claimed in claim 19, wherein the number-average molar mass Mn of the copolyimide is between 500 g/mol and 50,000 g/mol.

28. A process for manufacturing a copolyimide, comprising copolymerizing at least: (a) an aromatic compound comprising two anhydride functions and/or carboxylic acid and/or ester derivatives thereof; (b) a diamine of formula (I) NH2RNH2 selected from the group consisting of: 1,4-diaminobutane, 1,5-diaminopentane, 2-methyl-1,5-diaminopentane, hexamethylenediamine, 3-methylhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,2,4- and 2,4,4-trimethyl-hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane; and (c) a diamine of formula (II) NH2RNH2 in which R is a saturated and/or unsaturated, linear or branched, divalent aliphatic hydrocarbon-based radical, optionally comprising heteroatoms, the two amine functions being separated by a number Y of carbon atoms, Y being between 10 and 20, the radical R comprising not more than 20 carbon atoms; wherein the copolyimide has at least two melting points Tf, and the melting points are between 50 C. and 330 C., measured by differential scanning calorimetry and heating the copolyimide from 20 C. at a rate of 10 C./minute.

29. A composition comprising at least one copolyimide as claimed in claim 19 and reinforcing or bulking fillers and/or impact modifiers and/or additives.

30. A process for producing a plastics article, comprising forming at least one copolyimide as claimed in claim 19.

31. The process of claim 28, wherein the step of forming comprises injection molding, melt extrusion, extrusion-blow molding, or rotary molding of the polyamide or placing the polyamide, in the solid or molten state, in contact with a fabric.

32. A salt of tetracarboxylic acid and of diamines in which a chain limiter is also present and/or which has a stoichiometric imbalance.

33. A process for preparing a (co)polyimide comprising polymerizing a salt according to claim 32.

34. The process according to claim 28, wherein the diamine of formula (I) is mixed with the diamine of formula (II), and then the mixture comprising the diamine of formula (I) and diamine of formula (II) is added to the aromatic compound.

Description

EXPERIMENTAL SECTION

[0097] Measuring standards:

[0098] The melting point (Tf) and the crystallization temperature on cooling (Tc) of the copolyimides are determined by differential scanning calorimetry (DSC) by means of a Perkin Elmer Pyris 1 instrument, at a rate of 10 C./min. The Tf and Tc of the copolyimides are determined at the top of the melting and crystallization peaks. The glass transition temperature (Tg) is determined on the same machine at a rate of 40 C./min (when possible, it is determined at 10 C./min and specified in the examples). The measurements are taken after melting the copolyimide formed at T>(Tf of the copolyimide +20 C.).

[0099] For the determination of the melting point of the salt, the end temperature of the endotherm measured by heating the salt at 10 C./min is considered.

[0100] Thermogravmetric analysis (TGA) is performed on a Perkin-Elmer TGA7 machine on a sample of about 10 mg. The precise conditions of use (temperature, time, heating rate) are defined in the examples.

[0101] The Fourier-transform infrared (FTIR) analysis is performed on a Brker Vector 22 machine (in reflection, ATR Diamant) on the powder of formed copolyimide.

EXAMPLE 1

Preparation of Copolyimides PI 10PMA/12PMA of 100/0, 75/25, 50/50, 25/75 and 0/100 mol/mol by Synthesis of Co-Salts

[0102] An ethanolic solution of pyromellitic acid is prepared by dissolving 0.00079 mol of pyromellitic acid in 4 mL of absolute ethanol. This solution is added dropwise to a solution heated to 50 C. containing 5 mL of absolute ethanol and 0.00079 mol of a mixture of 1,10-diaminodecane and 1,12-diaminododecane in 100%/0% (Example 1A), 75%/25% (Example 1B), 50%/50% (Example 1C), 25%/75% (Example 1D) and 0%/100% (Example 1E) mole proportions. During the introduction of the pyromellitic acid solution into the diamine mixture, the salt formed precipitates out immediately and is recovered by evaporating off the solvent. The salt is dried overnight under vacuum at 50 C.

[0103] The copolyimide formed is prepared by heat treatment above 200 C. of the salt powder and then analyzed by DSC in Table 1 below:

TABLE-US-00001 TABLE 1 Tf Salt TfPI HfPI TcPI TgPI* PI 10PMA/12PMA C. C. J/g C. C. 1A (homopolyimide) 245 334 47 306 115 1B 242 294 19 274 109 1C 237 269 26 255 104 1D 238 285 30 261 100 1E (homopolyimide) 260 303 35 274 96 *The Tg is determined at 10 C./min

[0104] It is also observed in Table 1 that the copolyimides are semicrystalline and have only one melting point, meaning that they are copolymers that are capable of co-crystallizing. This melting point may be between the Tf values of the two homopolyimides or even lower. It also appears that the heat of fusion is lower than the heat of fusion of the homopolymers but that it remains high irrespective of the molar composition of the diamines. Starting from the copolymerization, it is possible to transform the PI10PMA with a melting point of 334 C. that is difficult to transform via thermoplastic transformation techniques into a semicrystalline polymer with a melting point of less than 300 C. which is much easier to transform.

[0105] It will be noted that the FTIR analysis of the copolyimide powder has the characteristic absorption bands of imide functions at 1700 and 1767 cm-1 and the absence of characteristic absorption bands of amide functions is noted.

EXAMPLE 2

Preparation of Copolyimides PI 10PMA/13PMA of 100/0, 75/25, 50/50, 25/75 and 0/100 mol/mol by Synthesis of Co-Salts

[0106] According to the same procedure as previously, an ethanolic solution of pyromellitic acid is this time added dropwise to a stoichiometric amount of a mixture of 1,10-diaminodecane and 1,13-diaminotridecane dissolved in pure ethanol. The mole ratio chosen for the two C10/C13 diamines is 100%/0% (example 2A), 75%/25% (example 2B), 50%/50% (example 2C), 25%/75% (example 2D) and 0%/100% (example 2E). The salts formed precipitate out immediately and are recovered by evaporating off the solvent, and dried overnight under vacuum at 50 C.

[0107] The copolyimide formed is prepared by heat treatment above 200 C. of the salt powder and then analyzed by DSC in Table 2 below:

TABLE-US-00002 TABLE 2 Tf Salt TfPI1 TfPI2 HfPI1 HfPI2 TcPI1 TcPI2 TgPI * PI 10PMA/13PMA C. C. C. J/g J/g C. C. C. 2A (homopolyimide) 245 334 47 306 115 2B 254 325 310 15 8 291 291 N.D. 2C 234 299 276 5 4 262 205 N.D. 2D 238 256.7 249 7 7 231 227 N.D. 2E (homopolyimide) 230 271 36 238 N.D. * The Tg is determined at 10 C./min N.D. = not determined

[0108] It is first observed, as for the copolyimides PI 10PMA/12PMA of Example 1, that all the copolyimides PI 10PMA/13PMA are semicrystalline, but it is also observed in Table 2 that they have not just one melting point but two melting points TfPI1 and TfPI2, and associated enthalpies, and two crystallization temperatures TcPI1 and TcPI2. In all cases, they are copolymers, and not mixtures of homopolymers, since: [0109] their melting points are different from the melting points of the homopolymers, [0110] the sum of their associated heats of fusion is less than the sum of the enthalpies of the homopolymers in the proportions under consideration.

EXAMPLE 3

Preparation of Copolyimides PI 6PMA/10PMA by Synthesis of Co-Salts or Mixed Salts

[0111] The three ethanolic solutions are prepared in the following manner: [0112] Solution 1. 2.807 g of 97.6% pyromellitic acid dissolved in 51.806 g of absolute ethanol. Solution 1 has a concentration of 1.974x10-4 mol/g of pyromellitic acid. [0113] Solution 2. 0.831 g of an aqueous solution of hexamethylenediamine (C6 diamine) at 32.25% by weight dissolved in 16.754 g of ethanol. Solution 2 has a concentration of 1.31110-4 mol/g of hexamethylenediamine. [0114] Solution 3. 2.202 g of 99% 1,10-diaminodecane (C10 diamine) dissolved in 41.992 g of ethanol. Solution 3 has a concentration of 2.86310-4 mol/g of 1,10-diaminodecane.

[0115] Mixtures of the solutions of diamines 1 and 2 are prepared so as to have mole proportions of C6/C10 diamines equal to 0%/100% (Example 3A), 10%/90% (Example 3B), 15%/85% (Example 3C), 20%/80% (Example 3D) and 30%/70% (Example 3E). These diamine mixtures are then added with stirring to an amount of solution 1 so as to have a stoichiometric amount of diamines (0.0024 mol) and of pyromellitic acid (0.0024 mol). Stirring is maintained for 30 minutes. The salt formed precipitates out and is recovered by evaporating off the solvent, and then dried overnight under vacuum at 45 C.

[0116] The copolyimide formed is prepared by heat treatment at 200 C. for 4 hours of the salt powder while flushing with nitrogen, and then analyzed by DSC in Table 3.

TABLE-US-00003 TABLE 3 TfPI1 TfPI2 HfPI1 HfPI2 TcPI PI 6PMA/10PMA C. C. J/g J/g C. 3A (homopolyimide) 338 326 27 18 305 3B 329 319 12 22 300 3C 326 316 9 22 295 3D 322 310 5 24 288 3E 325 313 6 16 289

[0117] With this synthetic process, we obtain a double melting peak for PI 10PMA. It is observed in Table 3 that the copolyimides PI 6PMA/10PMA in the zone of molar compositions ranging from 0%/100% to 30%/70% are all semicrystalline. They have two melting points that are different and above all below the melting points of the homopolyimide PI 10PMA (Tf=338 C. and Tf=326 C.), meaning that they are indeed copolymers (insertion of C6 diamine into the PI 10PMA chain) and not mixtures of homopolymers. It is also seen that the sum of the heats of fusion of the two melting peaks of the copolymers is less than the sum of the heats of fusion of the two melting peaks of the homopolyimide PI 10PMA, but that it remains high irrespective of the molar composition of the diamines. Starting from the copolymerization by preparation of PI 6PMA/10PMA co-salts according to this procedure, it is possible to lower the highest melting point of PI 10PMA to about 322 C. (16 C.).

EXAMPLE 4

Preparation of Copolyimides PI 6PMA/10PMA by Sequential Addition of the Monomers

[0118] In contrast with Example 3 in which a mixture of C6 and C10 diamines is introduced into a pyromellitic acid solution, a sequential introduction of the diamines into the pyromellitic acid solution is performed here in Example 4: [0119] To begin with, the ethanolic solution of hexamethylenediamine (solution 2) is introduced into the pyromellitic acid solution (solution 1). [0120] The ethanolic solution of 1,10-diaminodecane (solution 3) is then introduced into the mixture of solution 1 and solution 2 thus constituted. [0121] Stirring is maintained for 30 minutes. The salt formed precipitates out and is recovered by evaporating off the solvent, and then dried overnight under vacuum at 45 C.

[0122] The introductions are performed so as to have finally 0.0024 mol of pyromellitic acid and 0.0024 mol of diamines. The molar proportions of C6/C10 diamines are respectively equal to 0%/100% (Example 4A), 10%/90% (Example 4B), 15%/85% (Example 4C), 20%/80% (Example 4D) and 30%/70% (Example 4E).

[0123] The copolyimide formed is prepared by heat treatment at 200 C. for 4 hours of the salt powder while flushing with nitrogen, and then analyzed by DSC in Table 4 below.

TABLE-US-00004 TABLE 4 TfPI1 TfPI2 HfPI1 HfPI2 TcPI PI 6PMA/10PMA C. C. J/g J/g C. 4A (homopolyimide) 338 326 27 18 306 4B 333 322 19 16 303 4C 334 323 12 22 303 4D 338 326 13 16 303 4E 334 323 17 15 308

[0124] It is seen that the melting points and crystallization temperatures of PI 10PMA are virtually unchanged irrespective of the mole proportions of C6 diamine. It is seen, by comparison of the thermal properties of the copolymers of Examples 3 and 4, that the mode of introduction of the monomers and comonomers gives rise to different structures: rather statistical in Example 3 and rather block in Example 4.