Highly-selective polyimide membranes with increased permeance, said membranes consisting of block copolyimides

Abstract

The present invention relates to novel block copolyimides for preparing highly selective integrally asymmetrical gas separation membranes of improved permeance, processes for preparing these block copolyimides, membranes prepared from the block copolyimides, and also the use of the block copolyimides and of the membranes prepared therefrom.

Claims

1. A block copolyimide, comprising the blocks (A) and (B) having the following structures (Ia) and (Ib) ##STR00015## wherein R1 comprises either or both of the functional groups R.sub.1a or R.sub.1b ##STR00016## R2 comprises at least one of the functional groups R.sub.2a, R.sub.2b or R.sub.2c ##STR00017## R3 comprises at least one of the functional groups R.sub.3a, R.sub.3b or R.sub.3c ##STR00018## and R4 comprises at least one of the following functional groups R.sub.4a, R.sub.4b or R.sub.4c ##STR00019## wherein at least one of the radicals X.sub.1 to X.sub.4, are equal to CH.sub.3 or a C.sub.2 to C.sub.4 alkyl radical and the functional groups R.sub.1 to R.sub.4 are selected such that the blocks A and B have a differing composition, wherein block lengths n and m of blocks (A) and (B) are each from 5 to 1000, and wherein the block copolyimide is soluble in an aprotic dipolar solvent.

2. The block copolyimide according to claim 1, wherein the block lengths n and m of blocks (A) and (B) are each from 5 to 150, and/or the molecular weight M.sub.n of the block copolyimide is, based on polystyrene standards, in the range from 10,000 to 200,000 g/mol, and/or the molecular weight M.sub.w of the block copolyimide is in the range from 10,000 to 500,000 g/mol, and/or the polydispersity index is in the range from 1 to 10.

3. The block copolyimide according to claim 1, wherein the block (B) in isolated form is soluble in an aprotic dipolar solvent.

4. The block copolyimide according to claim 1, wherein R.sub.1 consists in total to an extent >50 mol %, of groups R.sub.1a and R.sub.1b and also any further tetravalent, aromatic, functional groups, and/or R.sub.2 consists in total to an extent >50 mol %, of groups R.sub.ea, R.sub.2b and/or R.sub.2c and any further divalent, aromatic, functional groups, and/or R.sub.3 consists in total to an extent >50 mol %, of groups R.sub.3a, R.sub.3b and/or R.sub.3c and also any further tetravalent, aromatic, functional groups, and/or R.sub.4 consists in total to an extent >50 mol %, of groups R.sub.4a, R.sub.4b and/or R.sub.4c and any further divalent, aromatic, functional groups.

5. The block copolyimide according to claim 4, wherein R.sub.1 consists of 0 to 100 mol % R.sub.1a and 0 to 100 mol % R.sub.1b, wherein the mole percentages of the functional groups R.sub.1a and R.sub.1b are in each case chosen within the recited ranges such that they total 100 mol % of functional groups R.sub.1, and/or R.sub.2 consists of 0 to 100 mol % R.sub.2a and/or 0 to 100 mol % R.sub.2b and/or 0 to 100 mol % R.sub.2c, wherein the mole percentages of the functional groups R.sub.2a, R.sub.2b and R.sub.2c are in each case chosen within the recited ranges such that they total 100 mol % of functional groups R.sub.2, and/or R.sub.3 consists of 0 to 100 mol % R.sub.3a and/or 0 to 100 mol % R.sub.3b and/or 0 to 100 mol % R.sub.3c, wherein the mole percentages of the functional groups R.sub.3a, R.sub.3b and R.sub.3c are in each case chosen within the recited ranges such that they total 100 mol % of functional groups R.sub.3 and/or R.sub.4 consists of 0 to 100 mol % R.sub.4a and 0 to 100 mol % R.sub.4b and 0 to 100 mol % R.sub.4c, wherein the mole percentages of the functional groups R.sub.4a, R.sub.4b and R.sub.4c are in each case chosen within the recited ranges such that they total 100 mol % of functional groups R.sub.4.

6. The block copolyimide according to claim 1, wherein: block (A) consists of: 100 mol % R.sub.1b, 64 mol % R.sub.2a, 16 mol % R.sub.2b and 20 mol % R.sub.2c, or 40 mol % R.sub.1a, 60 mol % R.sub.1b, 80 mol % R.sub.2a and 20 mol % R.sub.2b, and block (B) consists of 40 to 60 mol % R.sub.3a, 0 to 10 mol % R.sub.ab, 60 to 30 mol % R.sub.3c, 90 to 100 mol % R.sub.4a, 0 to 10 mol % R.sub.0b and 0 to 10 mol % R.sub.0c, or 50 mol % R.sub.3a, 50 mol % R.sub.1c and 100 mol % R.sub.4a, wherein the recited mole percentages relate to the functional groups R.sub.1, R.sub.2, R.sub.3 and R.sub.4 such that the amounts of the various units are each selected such that the sum total is 100 mol % for each of these groups.

7. A process for preparing a block copolyimide according to claim 1, comprising the following steps: a. preparing an oligoimide having terminal anhydrides from at least one dianhydride of formula (II) ##STR00020## and at least one diamine of formula (III)
H.sub.2NR.sub.4NH.sub.2(III) wherein R.sub.3 and R.sub.4 are each as defined in claim 1, and b. reacting the oligo/polyimide of step a) with at least one dianhydride of formula (IV) ##STR00021## and at least one diisocyanate (V)
OCNR.sub.2NCO(V) wherein R.sub.1 and R.sub.2 are each as defined in claim 1, to form a block copolyimide.

8. The process according to claim 7, wherein step a) comprises the following subsidiary steps: a1) preparing an oligoamide acid from at least one diamine of formula (III) and at least one dicarboxylic anhydride of formula (II) in an aprotic dipolar solvent, wherein the dicarboxylic anhydride is present in molar excess, a2) imidating the oligoamide acid, a3) precipitating the oligoimide of step a2) a4) washing, and a5) drying, and/or conditioning.

9. The process according to claim 8, wherein the imidating in step a2) is effected thermally or chemically, wherein chemical imidizing is effected by adding a base and a water-withdrawing agent.

10. The process according to claim 9, wherein the base comprises tertiary organic amines and/or basic salts.

11. The process according to claim 7, wherein the step b) comprises the following subsidiary steps: b1) preparing a solution of the oligoimide of step a) in an aprotic dipolar solvent together with PMDA and/or with BTDA and with a basic catalyst, and b2) adding at least one diisocyanate selected from the group consisting of 2,4-TDI, 2,6-TDI and 4,4-MDI to form a block copolymer.

12. A process for preparing a block copolyimide according to claim 1, comprising the following steps: (i) preparing an oligoimide having terminal anhydrides from at least one dianhydride of formula (IV) ##STR00022## and at least one diisocyanate of formula (V)
OCNR.sub.2NCO(V) wherein R.sub.1 and R.sub.2 are each as defined in claim 1, and (ii) preparing a polyimide/polyamide acid block copolymer by reacting block (A) as obtained from step (i) with at least one dianhydride of formula (II) ##STR00023## and at least one diamine of formula (III)
H.sub.2NR.sub.4NH.sub.2(III), wherein R.sub.3 and R.sub.4 are each as defined in claim 1, and/or a block (B) having terminal amino groups, prepared from at least one dianhydride of formula (II) and at least one diamine of formula (III), and (iii) chemically imidating the polyimide/polyamide acid copolymer formed in step iii).

13. An asymmetrically integral hollow fiber membrane or asymmetrically integral flat sheet membrane prepared from a block copolyimide according to claim 1.

14. A hollow fiber membrane module comprising an asymmetrically integral hollow fiber membrane according to claim 13.

15. A process for separation of gases, comprising separating a gas mixture with an asymmetrically integral hollow fiber membrane or asymmetrically integral flat sheet membrane according to claim 13.

16. A device for separation of gases, comprising an asymmetrically integral hollow fiber membrane or asymmetrically integral flat sheet membrane according to claim 13.

17. An asymmetrically integral hollow fiber membrane or asymmetrically integral flat sheet membrane, prepared from a solution obtained by the process according to claim 7.

18. The process according to claim 7, wherein step b) is carried out using a tertiary organic amine or a basic salt as catalyst.

19. The block copolyimide according to claim 1, wherein R4 comprises at least one R.sub.4c functional group.

Description

EXAMPLE 1: PREPARING A POLYMERIC/OLIGOMERIC BLOCK (B)

(1) a) Preparing the Poly/Oligo Amide Acid (Degree of Polymerization m=20)

(2) In a 250 ml flask equipped with reflux condenser, mechanical stirrer and nitrogen flushing, 17.10 g (0.114 mol) of 2,4,6-trimethylbenzene-1,3-diamine (MesDA) are dissolved in 161 g of DMF. The yellow solution is cooled down to 10? C. and a mixture of 19.32 g (0.06 mol) of 3,34,4-benzophenonetetracarboxylic dianhydride (BTDA) and 13.08 g (0.06 mol) of pyromellitic dianhydride (PMDA) is added step by step to the solution. The solution is subsequently warmed to room temperature and stirred for 8 h.

(3) b) Imidating the Oligomeric Polyamide Acid (Degree of Polymerization m=20)

(4) The solution prepared in Example 1, step a) of an oligomeric polyamide acid has added to it, dropwise, a mixture of 27.91 g (0.274 mol) of acetic anhydride with 28 g of DMF in gradual fashion using a dropping funnel. This is followed by the addition of 0.05 g of 1,4-diazabicyclo[2.2.2]octane (DABCO). The solution is subsequently stirred at room temperature for 8 h and at 70? C. for a further 8 h.

(5) After the reaction has ended, the oligoimide is precipitated in water. The precipitate is washed with copious water and then dried in a vacuum drying cabinet at 70? C. The dry oligoimide is then conditioned at 230-260? C. for 2 h.

(6) The gel permeation chromatography of the oligoimide reveals a molecular mass M.sub.n of 35 501 g/mol, M.sub.w of 54 348 g/mol, M.sub.p of 55 413 g/mol and a polydispersity of 1.52.

EXAMPLES 2 AND 3: PREPARING FURTHER BLOCKS (B) (DEGREES OF POLYMERIZATION M=10 AND/OR M=33)

(7) Varying the amount of 2,4,6-trimethylbenzene-1,3-diamine (MesDA) makes possible the preparation of oligoimides having different degrees of polymerization. The oligoimides are prepared according to the same procedure as that described in Example 1. The composition of the reaction mixture and of the amounts of BTDA, PMDA, MesDA, DABCO and acetic anhydride which are used therefor are summarized in Table 1.

(8) TABLE-US-00002 TABLE 1 Degree of Acetic polymer- anhy- ization BTDA PMDA MesDA DMF dride DABCO Ex. BPM [g/mol] [g/mol] [g/mol] [g] [g/mol] [g] 2 10 19.32 13.08 16.20 158.5 26.44 0.04 (0.06) (0.06) (0.108) (0.259) 3 33 19.32 13.08 17.46 161.9 28.49 0.05 (0.06) (0.06) (0.116) (0.279)

(9) The molecular weights of the oligoimides obtained are summarized in Table 2.

(10) TABLE-US-00003 TABLE 2 Polydis- Ex. M.sub.n [g/mol] M.sub.w [g/mol] M.sub.p [g/mol] persity 2 28314 47802 49561 1.69 3 50174 100135 100452 2.00

EXAMPLES 4-8: PREPARING AN OLIGOMER BLOCK BY VARYING THE EMPLOYED DIANHYDRIDES/DIAMINES (B)

(11) Varying the monomers usednot only mixtures or alternative dianhydrides but also mixtures of alternative diamines (mesitylenediamine [MesDA], 2,3,5,6-tetramethyl-p-phenylenediamine [DurDA], 4,4-diamino-3,3-diethyl-5,5-dimethyldiphenylmethane (DDDDPM) 4,4-diamino-3,3-dimethyldiphenylmethane (DDDPM))makes possible the preparation of novel oligoimides that are in accordance with the present invention and have novel properties. The oligoimides are prepared according to the same procedure as that described in Example 1. The composition of the reaction mixture and of the amounts of dianhydrides, diamines, DABCO and acetic anhydride which are used therefor are summarized in Table 3.

(12) TABLE-US-00004 TABLE 3 Acetic anhy- BTDA PMDA ODPA 6-FDA MesDA DurDA DDDDPM DDDPM DMF dride DABCO Ex. [g (mol)] [g (mol)] [g (mol)] [g (mol)] [g (mol)] [g (mol)] [g (mol)] [g (mol)] [g] [g (mol)] [g] 4 27.05 15.99 17.10 198.7 27.91 0.06 (0.084) (0.036) (0.114) (0.274) 5 11.59 26.06 17.10 179.56 27.91 0.06 (0.036) (0.084) (0.114) (0.274) 6 6.44 4.36 10.37 71.50 9.30 0.02 (0.020) (0.020) (0.038) (0.091) 7 6.44 4.36 8.60 63.94 9.30 0.02 (0.020) (0.020) (0.038) (0.091) 8 13.52 9.16 7.98 2.18 3.76 119.60 19.54 0.03 (0.042) (0.042) (0.053) (0.013) (0.013) (0.192)

(13) The molecular weights of the oligoimides obtained are summarized in Table 4.

(14) TABLE-US-00005 TABLE 4 Polydis- Ex. M.sub.n [g/mol] M.sub.w [g/mol] M.sub.p [g/mol] persity 4 40164 73929 75908 1.84 5 38810 78853 78771 2.03 6 47041 95282 84396 2.03 7 74037 162969 126439 2.20 8 44329 79616 80057 1.80

EXAMPLE 9: PREPARING A BLOCK COPOLYIMIDE IN THE COMPOSITION OF BLOCKS A:B=45:55

(15) In a 250 ml flask equipped with reflux condenser, mechanical stirrer, nitrogen flushing and isocyanate metering, 19.32 g (0.06 mol) of 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA) and 8.72 g (0.04 mol) of pyromellitic dianhydride (PMDA) are presented as initial charge and 212.3 g of DMF are added. The reaction mixture is subsequently heated to 80? C. 45.40 g of the oligoimide (block (B)) from Example 2 are added to the solution. This is followed by the addition of 0.08 g of DABCO to the solution. The reddish brown solution subsequently has added to it 18.44 g (0.106 mol) of an isocyanate mixture consisting of 80% 2,4-tolylene diisocyanate and 20% 2,6-tolylene diisocyanate over 8 h with the evolution of CO.sub.2. The viscous solution is subsequently stirred at 80? C. until the reaction has ended.

(16) The viscous solution has a dynamic viscosity of 88 Pa.Math.s. The gel permeation chromatography of the block copolyimide solution shows a molecular weight M.sub.n of 77 006 g/mol, M.sub.w of 174 183 g/mol, M.sub.p of 127 156 g/mol and a polydispersity of 2.26.

EXAMPLES 10-15: PREPARATION OF FURTHER BLOCK COPOLYIMIDES OF DIFFERING COMPOSITION

(17) Different block copolyimides can be prepared on the basis of the procedure described in Example 9 by varying the ratios between blocks (A) and (B). The composition of each reaction batch is summarized in Table 5.

(18) TABLE-US-00006 TABLE 5 80% 2,4-TDI + Block 20% Ratio BTDA PMDA DMF (B) 2,6-TDI DABCO Ex. A/B [g/mol] [g/mol] [g] [g] [g/mol] [g] 10 70:30 55.55 25.07 338.3 45.40 51.07 0.15 (0.173) (0.115) (0.294) 11 65:35 44.11 19.91 333.2 45.40 40.77 0.13 (0.137) (0.091) (0.234) 12 55:45 28.98 13.08 259.4 45.40 27.14 0.10 (0.090) (0.060) (0.156) 13 50:50 23.67 10.68 233.5 45.40 22.36 0.09 (0.074) (0.049) (0.129) 14 40:60 15.68 7.08 194.5 45.40 15.17 0.08 (0.049) (0.032) (0.087) 15 25:75 7.70 3.47 155.6 45.40 7.98 0.06 (0.024) (0.016) (0.046)

(19) The block copolyimide solutions obtained were subsequently measured with regard to molecular weight and dynamic viscosity; the viscosities and molar masses characteristic for the block copolyimides are summarized in Table 6.

(20) TABLE-US-00007 TABLE 6 Dynamic Polydis- viscosity Ex. M.sub.n [g/mol] M.sub.w [g/mol] M.sub.p [g/mol] persity [Pa .Math. s] 10 75528 144515 131806 1.91 44 11 53454 127745 116475 2.39 62 12 56070 108207 103460 1.93 22 13 61648 114833 107564 1.86 18 14 63694 125253 115509 1.97 21 15 47371 142575 117321 3.01 46

EXAMPLES 16 AND 17: PREPARATION OF BLOCK COPOLYIMIDES HAVING DIFFERENT BLOCK LENGTHS FOR BLOCK (B)

(21) The operating instructions of Examples 9 to 15 can be used as a basis for preparing further block copolyimides, the properties of which can be adapted by varying the (B) block length. The oligoimides prepared in Examples 2 and 3 are used for this. The composition of the reaction mixtures is summarized in Table 7.

(22) TABLE-US-00008 TABLE 7 80% Degree of 2,4-TDI + polymer- Block 20% ization BTDA PMDA DMF (B) 2,6-TDI DABCO Ex. m BPM [g/mol] [g/mol] [g] [g] [g (mol)] [g] 16 10 20.35 9.19 226.7 48.51 20.48 0.09 (0.063) (0.042) (0.118) 17 33 21.09 9.52 230.9 49.43 19.74 0.09 (0.066) (0.044) (0.234)

(23) The polymer solution was subsequently measured with regard to its molar mass and dynamic viscosity; the characteristic data are summarized in Table 8.

(24) TABLE-US-00009 TABLE 8 Dynamic Polydis- Viscosity Ex. M.sub.n [g/mol] M.sub.w [g/mol] M.sub.p [g/mol] persity [Pa .Math. s] 16 55269 107337 105828 1.94 24 17 52169 122785 123479 2.35 23

EXAMPLE 18: PREPARING A BLOCK COPOLYIMIDE HAVING ALTERNATIVE (A) BLOCK AND THE COMPOSITION A:B=55:45

(25) In a 250 ml flask equipped with reflux condenser, mechanical stirrer, nitrogen flushing and isocyanate metering, 24.3 g (0.075 mol) of 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA) are introduced as initial charge and 170.0 g of DMF are added. The reaction mixture is subsequently heated to 85? C. 25.2 g of the oligoimide from Example 1 are added to the solution. This is followed by the addition to the solution of 1 g of DABCO and 1.47 g of toluenediamine. The reddish brown solution subsequently has added to it 13.53 g (0.077 mol) of 2,4-tolylene diisocyanate over 8 h with the evolution of CO.sub.2. The viscous solution is subsequently stirred at 85? C. until the reaction has ended.

(26) The viscous solution has a dynamic viscosity of 17 Pa.Math.s. The gel permeation chromatography of the block copolyimide solution shows a molecular weight M.sub.n of 59 268 g/mol, M.sub.w of 138 236 g/mol, M.sub.p of 124 001 g/mol with a PDI of 2.33.

EXAMPLE 19: PREPARING A BLOCK COPOLYIMIDE HAVING ALTERNATIVE (A) BLOCK AND THE COMPOSITION A:B=52:48

(27) In a 250 ml flask equipped with reflux condenser, mechanical stirrer, nitrogen flushing and isocyanate metering, 24.15 g (0.075 mol) of 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA) are introduced as initial charge and 187.7 g of DMAc are added. The reaction mixture is subsequently heated to 85? C. 29.80 g of the oligoimide from Example 1 are added to the solution. This is followed by the addition of 0.20 g of DABCO. The reddish brown solution subsequently has added to it 14.95 g (0.079 mol) of an isocyanate mixture consisting of 80% tolylene diisocyanate (80% 2,4-tolylene diisocyanate and 20% 2,6-tolylene diisocyanate) and 20% 4,4-methylenebis(phenyl isocyanate) (MDI), over 4.7 h with the evolution of CO.sub.2. The viscous solution is subsequently stirred at 85? C. until the reaction has ended.

EXAMPLES 20-24: PREPARING A BLOCK COPOLYIMIDE HAVING ALTERNATIVE (B) BLOCK AND THE COMPOSITION A:B=45:55

(28) The operating instructions of Examples 9 to 15 can be used as a basis for preparing further block copolyimides, the properties of which can be adapted by varying the (B) block composition. The oligoimides prepared in Examples 4 to 8 are used for this. The composition of the reaction mixtures is summarized in Table 9.

(29) TABLE-US-00010 TABLE 9 80% (B) 2,4-TDI + Block Block 20% from BTDA PMDA DMF (B) 2,6-TDI DABCO Ex. Ex [g (mol)] [g (mol)] [g] [g] [g (mol)] [g] 20 4 10.67 4.82 116.9 25.0 10.08 0.05 (0.033) (0.022) (0.058) 21 5 12.78 9.52 140.3 30.0 12.13 0.09 (0.040) (0.026) (0.070) 22 6 6.39 2.89 70.1 15.0 6.02 0.03 (0.020) (0.013) (0.035) 23 7 6.40 2.89 70.2 15.0 6.05 0.03 (0.020) (0.013) (0.035) 24 8 8.51 3.84 93.5 20.0 8.10 0.04 (0.026) (0.018) (0.035)

(30) The polymer solution was subsequently measured with regard to its molar mass; the characteristic data are summarized in Table 10.

(31) TABLE-US-00011 TABLE 10 Polydis- Ex. M.sub.n [g/mol] M.sub.w [g/mol] M.sub.p [g/mol] persity 20 51417 117337 106851 2.28 21 51276 110628 86517 2.16 22 38403 108133 45567 2.82 23 35614 120157 28816 3.37 24 57221 129584 119094 2.26

EXAMPLES 25-29: PREPARATION AS PER SECOND PREFERRED EMBODIMENT OF PROCESS ACCORDING TO THE PRESENT INVENTION WITH AN (A) BLOCK HAVING A DEGREE OF POLYMERIZATION N=19

(32) i) Preparation of (A) Block (Block Length n=10) in Solution:

(33) In a 2 L flask equipped with reflux condenser, mechanical stirrer, nitrogen flushing and isocyanate metering, 325.05 g (1.009 mol) of 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA) are introduced as initial charge and 1229.4 g of DMF are added. The reaction mixture is subsequently heated to 90? C. This is followed by the addition of 1.15 g of DABCO and 0.56 g of 2,4-toluenediamine. The reddish brown solution subsequently has added to it 157.18 g (0.908 mol) of 2,4-tolylene diisocyanate over 200 min with the evolution of CO.sub.2. The viscous solution is subsequently stirred at 90? C. until the reaction has ended. The solution is then emptied into a 2 L measuring flask and diluted to 2 L with DMF.

(34) ii) Preparing the Block Copolyimide

(35) In a flask, an initial charge of MesDA is dissolved with a defined amount of DMF. The solution is cooled to around 15? C. A mixture of PMDA and BTDA is then added in small portions.

(36) Following full reaction of the dianhydride with MesDA, a defined volume of the block (A) oligomer solution is added dropwise to the solution. Small amounts of BTDA are metered in subsequently to achieve high viscosities. The solution is stirred at 15? C. for a further 5 h to complete the reaction.

(37) iii) Imidation

(38) This is followed by the rapid dropwise addition of a mixture of acetic anhydride and pyridine and subsequent stirring at room temperature for an hour. The solution is stirred at 60? C. for a further 12 h to obtain an orange solution.

(39) Block copolyimides having different ratios between the (A) and (B) blocks are preparable by varying the initial weights. The initial weights used are summarized in Table 11.

(40) TABLE-US-00012 TABLE 11 Block (A) Acetic olig- acid omer Pyri- anhy- Ratio MesDA BTDA PMDA DMF solution dine dride Ex. A/B [g/mol] [g/mol] [g/mol] [g] [ml] [g] [g] 25 40:60 5.85 5.88 3.98 35 50 12.95 8.36 (0.039) (0.018) (0.018) 26 45:55 5.81 5.74 3.89 35 60 12.84 8.29 (0.039) (0.018) (0.018) 27 50:50 4.83 4.70 3.18 30 69 10.68 6.89 (0.032) (0.015) (0.015) 28 55:45 4.71 4.48 3.03 30 70 10.41 6.72 (0.031) (0.014) (0.014) 29 60:40 3.93 3.65 2.47 30 70 8.69 5.61 (0.026) (0.011) (0.011)

(41) The polymer solutions were subsequently measured for their molar masses by gel permeation chromatography. Characteristic molar masses are summarized in Table 12.

(42) TABLE-US-00013 TABLE 12 A:B where in the case of A Polydis- Ex. (n = 10) M.sub.n [g/mol] M.sub.w [g/mol] M.sub.p [g/mol] persity 25 40:60 89644 186153 175438 2.08 26 45:55 89731 181403 172219 2.02 27 50:50 74543 143948 142731 1.93 28 55:45 85964 176288 165535 2.05 29 60:40 79550 155592 150242 1.96

EXAMPLES 30-40: PREPARING A BLOCK COPOLYIMIDE HAVING DEFINED (A) BLOCKS (N=39 AND N=66)

(43) Proceeding on the basis of the operating procedure described in Examples 25-29, varying the amounts of 2,4-tolylene diisocyanate makes it possible to prepare oligoimides (block (A)) having differing block length (n=20 or n=33) and thus, after reaction with MesDA, PMDA and BTDA, further, novel block copolyimides. The composition of the reaction mixtures for preparing the oligoimides solution and the block copolyimide solution are summarized in Tables 13+14.

(44) Preparation of (A) block oligoimide solutions having different block lengths:

(45) TABLE-US-00014 TABLE 13 BTDA 2.4 TDI DABCO 2,4-Toluene- [g/mol] [g/mol] DMF [g] [g] diamine [g] Block A 325.05 166.93 1229.43 1.15 0.56 (n = 20) (1.009) (0.958) Block A 325.05 170.44 1229.43 1.15 0.34 (n = 33) (1.009) (0.978)

(46) Preparation of block copolyimides having both (A) blocks and different ratios A:B.

(47) TABLE-US-00015 TABLE 14 Block A Block A Acetic (n = 39) (n = 66) Pyri- anhy- MesDA BTDA PMDA DMF Solution Solution dine dride Ex. A:B [g/mol] [g/mol] [g/mol] [g] [ml] [ml] [g] [g] 30 40:60 5.67 5.88 3.98 35 50 12.53 8.09 (0.038) (0.018) (0.018) 31 45:55 5.58 5.74 3.89 35 60 12.35 7.97 (0.037) (0.018) (0.018) 32 50:50 4.60 4.70 3.18 30 69 10.18 6.57 (0.031) (0.015) (0.015) 33 55:45 4.44 4.48 3.03 30 70 9.83 6.34 (0.030) (0.014) (0.018) 34 60:40 3.67 3.65 2.47 30 70 8.11 5.24 (0.024) (0.011) (0.014) 35 25:75 7.73 8.21 5.55 60 35 17.10 11.04 (0.052) (0.026) (0.026) 36 35:65 6.90 7.27 4.92 60 50 15.25 9.84 (0.046) (0.023) (0.023) 37 45:55 5.49 5.74 3.89 55 60 12.15 7.84 (0.037) (0.018) (0.018) 38 55:45 4.65 4.80 3.25 50 75 10.28 6.63 (0.031) (0.015) (0.015) 39 65:35 3.11 3.16 2.14 35 75 6.89 4.45 (0.021) (0.001) (0.001) 40 75:25 2.66 2.61 1.77 30 100 5.88 3.79 (0.018) (0.008) (0.008)

(48) All resulting block copolyimide solutions were measured for their molar mass. Characteristic molecular weights are summarized in Tables 15 and 16:

(49) TABLE-US-00016 TABLE 15 A:B where A Polydis- Ex. (n = 20) M.sub.n [g/mol] M.sub.w [g/mol] M.sub.p [g/mol] persity 30 40:60 76779 162275 147753 2.11 31 45:55 83294 177832 159160 2.14 32 50:50 66720 125666 120010 1.88 33 55:45 72307 143676 133666 1.99 34 60:40 74012 157401 135920 2.13

(50) TABLE-US-00017 TABLE 16 A:B with A Polydis- Ex. (n = 33) M.sub.n [g/mol] M.sub.w [g/mol] M.sub.p [g/mol] persity 35 25:75 83468 234403 230832 2.81 36 35:65 81717 198041 181587 2.42 37 45:55 111354 178408 157482 1.60 38 55:45 66322 140685 131396 2.12 39 65:35 110925 205280 155428 1.85 40 75:25 50646 93336 93699 1.84

EXAMPLE 41: PREPARATION OF FOILS FROM THE BLOCK COPOLYIMIDE SOLUTIONS PRODUCED IN EXAMPLES 9-39

(51) The block copolyimide solutions from Examples 9-39 are filtered through a filtration cell having a 15 ?m filter and are then devolatilized in a desiccator. The foils are prepared using an Elcometer 4340 applicator with temperature-regulatable table. This table is temperature regulated to 30? C. The block copolymer solution is filled into the blade coater and applied to the temperature-regulated glass plate at a constant speed of drawdown. The blade gap is 400 ?m during the process. The glass plate is subsequently dried at 70? C. in a circulating air drying cabinet for one hour, then at 150? C. for a further hour and at 250? C. for a further 12 h. After cooling at room temperature, the foils are detached from the glass plate in a waterbath and dried. The foils have a thickness of 30-50 ?m and good mechanical properties.

(52) The dry foils are inspected to select flawless areas and circularly round samples 46 mm in diameter are cut out to measure the permeabilities and selectivities. The permeabilities of a very wide variety of gases are determined by the vacuum method. In this method, the foils are subjected to a single gas (e.g. nitrogen, oxygen, methane or carbon dioxide) at various pressures and the increase in the pressure on the permeate side is recorded. This is used to compute the permeability in barrers.

(53) The intrinsic permeabilities and selectivities of the individual block copolyimides are summarized in Table 17. The comparative examples used are foils obtained by the above method from the commercially available polymers P84 type 70 and P84 HT from Evonik Fibers GmbH.

(54) TABLE-US-00018 TABLE 17 Thickness P (O.sub.2) P (N2) Sel. P (CO.sub.2) P (CH.sub.4) Sel. Polymer [?m] [barrer] [barrer] O.sub.2/N.sub.2 [barrer] [barrer] CO.sub.2/CH.sub.4 Comparative 23.4 0.18 0.02 10.0 0.57 0.01 67.2 Example 1 P84 type 70 Comparative 41.4 0.53 0.04 13.2 1.69 0.01 169 Example 2 P84HT Example 9 29.1 3.81 0.49 7.8 (A:B = 45:55) Example 10 33.7 1.57 0.16 9.8 4.44 0.06 74.0 (A:B = 70:30) Example 11 49.2 2.38 0.26 9.0 7.70 0.12 66.8 (A:B = 65:35) Example 12 46.1 2.68 0.30 8.9 9.12 0.15 61.6 (A:B = 55:45) Example 13 37.9 3.24 0.44 7.3 (A:B = 50:50) Example 14 35.0 3.69 0.48 7.7 (A:B = 40:60) Example 15 46.4 5.06 0.76 6.7 28.15 0.71 39.9 (A:B = 25:75) Example 16 26.3 3.39 0.37 9.1 (A:B = 45:55 with B m = 10) Example 17 49.0 3.95 0.54 7.4 (A:B = 45:55 with B m = 10) Example 18 40.8 1.35 0.17 7.8 3.69 0.076 48.8 (A:B = 55:45) Example 19 25.4 1.92 0.26 7.3 (A:B = 52:48) Example 25 29.1 3.83 0.61 6.24 (A:B = 40:60 with A n = 10) Example 26 31.1 3.02 0.46 6.53 (A:B = 45:55 with A n = 10) Example 27 32.4 2.39 0.34 7.08 (A:B = 50:50 with A n = 10) Example 28 31.9 1.89 0.29 6.81 (A:B = 55:45 with A n = 10) Example 29 39.0 2.07 0.28 7.37 (A:B = 60:40 with A n = 10) Example 30 31.3 4.26 0.69 6.21 (A:B = 40:60 with A n = 20) Example 31 31.9 2.92 0.45 6.46 (A:B = 45:55 with A n = 20) Example 32 38.0 2.57 0.37 6.92 (A:B = 50:50 with A n = 20) Example 33 38.2 1.78 0.24 7.42 (A:B = 55:45 with A n = 20) Example 35 33.2 9.15 1.63 5.61 26.04 0.71 36.9 (A:B = 25:75 with A n = 33) Example 36 38.7 6.62 1.14 5.82 (A:B = 35:65 with A n = 33) Example 37 44.2 3.61 0.57 6.36 8.02 0.20 40.8 (A:B = 45:55 with A n = 33) Example 38 42.9 2.02 0.30 6.75 (A:B = 55:45 with A n = 33) Example 39 33.1 1.23 0.16 7.87 (A:B = 65:35 with A n = 33)

(55) For O.sub.2, the foils formed from the inventive block copolyimides were found to have permeabilities of 1.35 to 9.15 barrers. The prior art foils were found to have permeances of 0.18 and 0.53 barrers. Therefore, the permeabilities of the polymers according to the present invention are from 2.5 to 50.8 times better than those of the prior art polymers.

(56) For N.sub.2, the foils formed from the inventive block copolyimides were found to have permeabilities of 0.16 to 1.63 barrers. The prior art foils were found to have permeances of 0.02 and 0.04 barrers. Therefore, the permeabilities of the polymers according to the present invention are from 4 to 81.5 times better than those of the prior art polymers.

(57) As far as the selectivities are concerned, the foils formed from the inventive polymers were found to have values of 6.24 to 9.8 barrers for O.sub.2/N.sub.2. The prior art foils had values of 10 and 13.2. The selectivity of the inventive polymers is thus partly comparable, but at most 2.1 times worse than that of the prior art homopolymers. Weighing this slight loss of selectivity against the distinctly larger increase in the permeability by up to a factor of 81.5, the inventive polymers are found to embody a clear increase in permselectivity. The inventive polymers have a distinctly higher level of productivity for the gas pair O.sub.2/N.sub.2.

(58) These results were also confirmed for CO.sub.2/CH.sub.4. An increase in the permeability by a factor of 71 (cf. Example 26 with Comparative Example 1 or 2 for methane) was achieved. However, the selectivity decreased at most by a factor of 4 (cf. Example 26 with comparative example).

EXAMPLE 42: PREPARING A HOLLOW FIBER MEMBRANE FROM A BLOCK COPOLYIMIDE SOLUTION OF EXAMPLE 9

(59) A 27.5 wt % solution from Example 5 in DMF having a bulk viscosity of 65.9 Pa.Math.s.sup.?1 was thermostated to 50? C., devolatilized and filtered and gear pumped through a binary nozzle. The flow rate of the polymer solution was 337 g/h. While the polymer solution was conveyed in the exterior region of the binary nozzle, a mixture (bore solution) of 60% dimethylformamide and 40% water was conveyed on the inside in order to manufacture the hole in the hollow fibers. The flow rate of the bore solution was 110 ml/h. At a distance of 13 cm away from the nozzle, the hollow fiber entered warm water at 70? C. On the path between the nozzle and the coagulation bath, the hollow fiber was enveloped with a tube. A nitrogen stream of 1 l/min flowed through this tube after being preheated to 50? C. The fiber after the coagulation bath was pulled through a warm water wash bath at 70? C. and finally wound up at a speed of 50 m/min. Following an extraction with water for several hours, the hollow fibers were dipped into isopropanol. Following the exchange of solvents, the membranes were led at 70? C. through a drying sector and dried in about 40 seconds. During drying, the fiber was pulled once through a 0.3 wt % Sylgard 184 in isohexane solution and thereafter further dried. The membranes obtained contain about 2 wt % of residual water, ?0.5 wt % of residual solvent (isopropanol, isohexane) and <0.1 wt % of residual DMF and were subsequently heated at a heating rate of 2? C./min to a temperature of 310? C. in pure N.sub.2 (O.sub.2 content <0.001% by volume) and subsequently left at the final temperature for 1 h. After the annealing operation, the fibers were brought to below 250? C. as quickly as possible (about 5-10? C./min) and then further cooled down to room temperature.

(60) The hollow fiber membranes thus obtained had an O2 permeance of 46 GPU and an O.sub.2/N.sub.2 single gas selectivity of 7.8. A layer thickness of 83 nm was computed for the actively separating layer, based on O.sub.2, from the following formula:

(61) ${}^l\mathrm{HFM}=\frac{\mathrm{permeability}}{\mathrm{permeance}}*1000$

(62) where the layer thickness IHFM is in nm, the permeability is in barrers (10-10 cm3(STP).Math.cm.Math.cm-2.Math.s-1.Math.cmHg-1) and the permeance is in GPU (10-6 cm3(STP).Math.cm-2.Math.s-1.Math.cmHg-1). The permeance of hollow fiber membranes is determined as described in the methods of measurement section. The permeability, by contrast, is determined not on the hollow fiber membrane but on a foil of the same material, as described in the methods of measurement section. It must be noted in this connection that the permeability is a purely material property and/or polymer property and the permeance is a membrane property. Since the hollow fiber membrane is made from the same material as the foils, the intrinsic property of permeabilitydetermined on a foil basiscan be utilized to determine the layer thickness of hollow fiber membranes.

(63) A DMF solubility of 80% was determined for the hollow fiber membranes of this example. The strength and breaking extension of the fibers were 1.48 N and 17.7% respectively.

COMPARATIVE EXAMPLE 3: PREPARING A HOLLOW FIBER MEMBRANE FROM A P84HT SOLUTION OF WO 2011/009919 A1, EXAMPLE 7

(64) The P84 HT solution, in DMF, obtained from Example 7 of WO 2011/009919 A1 was thermostated to 50? C., devolatilized and filtered and gear pumped through a binary nozzle. The flow rate was 324 g/h. While the polymer solution was conveyed in the exterior region of the binary nozzle, a mixture (bore solution) of 70% dimethylformamide and 30% water was conveyed on the inside in order to manufacture the hole in the hollow fibers. The flow rate of the bore solution was 120 ml/h. At a distance of 13 cm away from the nozzle, the hollow fiber entered warm water at 50? C. On the path between the nozzle and the coagulation bath, the hollow fiber was enveloped with a tube. A nitrogen stream of 1 l/min flowed through this tube after being preheated to 50? C. The fiber was pulled through the warm water wash bath and finally wound up at a speed of 50 m/min. Following an extraction with water for several hours, the hollow fibers were dipped into isopropanol. Following this, the membranes were led at 70? C. through a drying sector and dried in about 40 seconds. The membranes obtained contain less than 2 wt % of water, ?0.5 wt % of residual solvent (isopropanol, hexane) and <0.1 wt % of residual DMF and were subsequently heated at a heating rate of 2? C./min to a temperature of 310? C. in pure N.sub.2 (O.sub.2 content <0.001% by volume) and subsequently left at the final temperature for 1 h. After the annealing operation, the fibers were brought to below 250? C. as quickly as possible (about 5-10? C./min) and then further cooled down to room temperature.

(65) The membranes obtained had an O.sub.2 permeance of 4.6 GPU and an O.sub.2/N.sub.2 single gas selectivity of 10.6. A separating layer thickness of 115 nm was computed. A DMF solubility of 70% was determined. The strength and breaking extension of the fibers were 2.04 N and 27.9% respectively.

COMPARATIVE EXAMPLE 4: PREPARING A HOLLOW FIBER MEMBRANE FROM A P84 TYPE 70 SOLUTION OF WO 2011/009919 A1, EXAMPLE 2

(66) The P84 type 70 solution obtained from WO 2011/009919 A1, Example 2 was thermostated to 50? C., devolatilized and filtered and gear pumped through a binary nozzle. The flow rate of the polymer solution was 324 g/h. While the polymer solution was conveyed in the exterior region of the binary nozzle, a mixture (bore solution) of 70% dimethylformamide and 30% water was conveyed on the inside in order to manufacture the hole in the hollow fibers. The flow rate of the bore solution was 120 ml/h. At a distance of 13 cm away from the nozzle, the hollow fiber entered warm water at 50? C. On the path between the nozzle and the coagulation bath, the hollow fiber was enveloped with a tube. A nitrogen stream of 0.5 l/min flowed through this tube after being preheated to 50? C. The fiber was pulled through the warm water wash bath and finally wound up at a speed of 50 m/min. Following an extraction with water for several hours, the hollow fibers were dipped into isopropanol. Following this, the membranes were led at 70? C. through a drying sector and dried in about 40 seconds. The membranes obtained contain less than 2 wt % of water, 0.5 wt % of residual solvent (isopropanol, hexane) and <0.1 wt % of residual DMF and were subsequently heated at a heating rate of 2? C./min to a temperature of 290? C. in pure N.sub.2 (O.sub.2 content <0.001% by volume) and subsequently left at the final temperature for 1 h. After the annealing operation, the fibers were brought to below 250? C. as quickly as possible (about 5-10? C./min) and then further cooled down to room temperature.

(67) The membranes obtained had an O.sub.2 permeance of 2.0 GPU and an O.sub.2/N.sub.2 single gas selectivity of 6.7. A separating layer (based on O.sub.2 thickness of 91 nm was computed. A DMF solubility of 70% was determined. The strength and breaking extension of the fibers were 2.16 N and 34.0% respectively.

(68) The O.sub.2 permeance of the hollow fiber membranes obtained is 10 times higher in Example 42 than in Comparative Example 3 and 23 times higher than in Comparative Example 4, in each of which the A blocks of the present invention were employed as homopolymers. This is particularly remarkable if only because there is but little difference between the thicknesses of the actively separating layers.