Polymerization process

Abstract

The present invention relates to a process comprising the step of melt-mixing a semi-aromatic polyamide (A) having a melting point on second heating of 295° C. or less comprising terephthalamide repeat units and a polyamide oligomer (B) comprising terephthalamide repeat units and having an amine end group concentration of less than 2000 me q/Kg and an inherent viscosity of at least 0.10, at a temperature which is greater than the melting point on first heating of both semi-aromatic polyamide (A) and polyamide oligomer (B) for a time period sufficient to produce semi-aromatic polyamide (C) having a melting point on second heating which is greater than or equal to 300° C.

Claims

1. A process comprising the step of melt-mixing a semi-aromatic polyamide (A) having a melting point on second heating of 295° C. or less comprising terephthalamide repeat units and a polyamide oligomer (B) having a melting point on second heating at least 10° C. greater than the melting point on second heating of semi-aromatic polyamide (A), said polyamide oligomer (B) comprising terephthalamide repeat units and having an amine end group concentration of less than 2000 me q/Kg and an inherent viscosity of at least 0.10 measured according to ISO 307:2007, at a temperature which is greater than the melting point on first heating of both semi-aromatic polyamide (A) and polyamide oligomer (B) for a time period sufficient to produce semi-aromatic polyamide (C) having a melting point on second heating which is greater than or equal to 300° C., wherein said melting points on first and second heating are determined according to ASTM D3418:2015.

2. The process of claim 1 wherein semi-aromatic polyamide (A) comprises repeat units derived from: (a) at least one dicarboxylic acid comprising: (i) greater than 20 to about 100 mole percent terephthalic acid; (ii) from 0 to about 80 mole percent dicarboxylic acid selected from isophthalic acid and aliphatic diacids comprising 4 to 20 carbon atoms; and (b) at least one aliphatic diamine having 4 to 20 carbon atoms; and optionally (c) an aliphatic lactam or an aliphatic amino carboxylic acid with 6 to 20 carbon atoms.

3. The process of claim 1 wherein polyamide oligomer (B) comprises the same terephthalamide repeat units of semi-aromatic polyamide (A).

4. The process of claim 1 wherein the semi-aromatic polyamide (A) is selected from the group consisting of: PA6T/6I, PA6T/610, PA6T/66, PA 6T/612, PA10T/1010, PA10T/101, PA 10T/11, PAST/510, PA6T/DT, PA4T/410, PA6T/9T, PA9T/10T, PAST/5I, PA6T/6I/6, and PA6T/6I/66.

5. The process of claim 1 in which the melt-mixing takes place in an extruder.

6. The process of claim 5 wherein the extruder is a twin-screw extruder.

7. The process of claim 1 wherein polyamide oligomer (B) has an amine end group concentration of less than or equal to 1000 meq/Kg and an IV of at least 0.15.

8. The process of claim 1 wherein the time period is less than 3 minutes.

9. The process of claim 1 wherein the time period is less than 1 minute.

10. The process of claim 1 wherein the weight percent of semi-aromatic polyamide (A) ranges from 60 to 90 and polyamide oligomer (B) ranges from 10 to 40 weight percent based on the weight percent of A and B.

11. The process of claim 1 wherein semi-aromatic polyamide (C) comprises at least 5 mole percent higher terephthalamide content than semi-aromatic polyamide (A).

12. The process of claim 1 wherein semi-aromatic polyamide (C) has an excess of amine end groups.

13. The process of claim 1 wherein semi-aromatic polyamide (C) has an excess of acid end groups.

14. The process of claim 1 wherein the melt-mixing temperature is between 425° C. and 250° C.

15. The process of claim 1 wherein the time period sufficient to produce semi-aromatic polyamide (C) ranges from about 15 seconds to 4 minutes.

16. The process of claim 1 wherein the melt-mixing temperature ranges from about 305° C. to 400° C.

17. The process of claim 1 wherein polyamide oligomer (B) comprises at least 10 mole percent higher content of terephthalamide repeat units than semi-aromatic polyamide (A), based on the total molar content of dicarboxylic acid repeat units in semi-aromatic polyamide (A).

18. The process of claim 17 wherein the terephthalamide repeat units are hexamethylene terephthalamide repeat units.

Description

EXAMPLES

(1) The novel processes and polyamides disclosed herein are further defined by the following Examples. It should be understood that these examples, while indicating certain preferred aspects of the disclosure, are given by way of illustration only. From the above discussion and these examples, one skilled in the art can ascertain the essential characteristics of this disclosure, and without departing from the spirit and scope thereof, can make various changes and modifications to adapt it to various uses and conditions.

(2) The exemplary articles are identified by “E” in the tables below are intended only to further illuminate and not to limit the scope of compounds, processes, and articles described and recited herein. Comparative examples are identified in the tables below by “C”.

(3) Test Methods

(4) Melting and Freezing Points

(5) Herein melting points and freezing points were determined by DSC (TA Instruments Q2000 or Q1000, TA Instruments, New Castle, Del., USA) at a scan rate of 10° C./min in the both first and second heating scans and in the cooling cycle according to ASTM D3418:2015 wherein the melting point is taken at the maximum of the endothermic peak and wherein the final temperature and isothermal hold time are as indicated in the tables. All samples were tested in aluminum pans under nitrogen at a purge rate of 50 ml/min. When two values are listed in the tables for a melting point, it indicates that the sample had two melting points. All melting points and freezing points in the tables are in ° C.

(6) For DSC data in tables 3A, 3B, 3C, and 3D a TA Instruments Q1000 was used with the following selections.

(7) Sample mass: 3+/−1 mg

(8) Sample form: pellet cut into quarters to obtain 3 mg sample

(9) For DSC data in tables 1B, 2A, 2B, 3E, 3F, and 3G a TA Instruments Q2000 was used with the following selections.

(10) Sample mass: 10+/−1 mg

(11) Sample form: pellets were cryogenically ground to fine powder

(12) Inherent Viscosity

(13) Inherent viscosity was measured in two different solvents depending on the material to be tested.

(14) Inherent viscosity (IV) was measured on a 0.5% solution of the polyamide to be tested in either 98% sulfuric acid or in m-cresol at 25° C., using a Schott AVS310 viscosity measuring unit, a Schott CK300 cooling unit, and a Schott CT52 constant temperature bath according to the method described in ISO 307:2007.

(15) Amine End Determination

(16) Amine Ends were measured in two different solvents depending on the material to be tested.

(17) Amine ends of the samples were determined by titrating a 1 percent solution of polyamide or oligomer in a phenol/methanol mixture (90:10 by volume) or hexafluoroisopropanol with 0.025 N perchloric acid solution. The end point was determined potentiometrically, using a Metrohm “Tiamo” operating system with a Titrando 809 and Dosino 800 burette, along with a Metrohm pH electrode, all available from Metrohm USA, Riverview, Fla., USA.

(18) Acid End Determination

(19) Polymer samples were dissolved in a blend (55:45 by volume) of two solvents: solvent 1=95:5 o-cresol/o-dichlorobenzene and solvent 2=20% lithium chloride in methanol; followed by addition of 1 wt % perchloric acid in methanol, in slight excess of the amount required to react with the amine ends until the solution is acidic. The polymer solutions were titrated with 0.04 N tetrabutylammonium hydroxide in benzyl alcohol, through the potentiometric endpoint for the excess perchloric acid, to the end point for the carboxyl ends. A Metrohm “Tiamo” operating system with a Titrando 809 and Dosino 800 burette, along with a Metrohm pH electrode, all available from Metrohm USA, Riverview, Fla., USA, was used. The difference in the titres for the two endpoints was used to calculate the carboxyl ends concentration.

(20) Materials

(21) In the compounds, processes, and articles exemplified in the tables below, the following materials were used. All percent values are by weight unless indicated otherwise.

(22) Synthesis of Semi-Aromatic Polyamide (A) 6T/6I

(23) The 6T/6I semi-aromatic polyamide (A) used in examples E1 to E13, E14a, E14b, C1a, and C1b were made in a 400-gallon agitated autoclave in a one-step all melt batch process as described below. Amounts of ingredients and temperatures used for each semi-aromatic polyamide (A) are listed in Table 1.

(24) A salt reactor was charged with hexamethylenediamine (HMD), water, terephthalic acid (TPA), isophthalic acid (IPA). The salt reactor is a jacketed agitated reactor with steam at the jacket to provide heat. The salt reactor was heated under nitrogen to 90° C. while continuously mixing the ingredients and at 15 psia to make a salt solution. Salt pH was measured to ensure the proper diamine to diacid ratio and adjusted accordingly with diamine or diacid. The salt solution was then pumped to a 400 gal autoclave and the remaining ingredients (acetic acid, sodium hypophosphate (SHP) and antifoam agent) were charged to the autoclave. The autoclave was heated while stirring to 160° C. and at a pressure of 65 psia for the evaporation cycle. The total evaporation cycle time was 120 to 130 minutes.

(25) The pressure on the now concentrated salt solution was increased in a first cycle from 65 psia to 265 psia over a time period of from 55 to 75 minutes. A pressure control valve was manipulated in a manner to achieve the desired pressure/temperature required for different cycles. The pressure was held constant at 265 psia in a second cycle while the temperature was increased from 160° C. to 230° C. at which point the pressure was gradually increased at 5.3 psi/min. to a final pressure of 345 psia. The temperature was also gradually increased during this time to a cycle two end temperature as indicated in table 1. The total reaction time for the second cycle was 85-95 min. During the third cycle, the pressure and temperature were slowly dropped in stages 3A to 3C as shown in table 1. During the final (vacuum) cycle (cycle 4), agitator power was used as an indication of the melt viscosity and molecular weight of polyamide resin (A). Vacuum cycle typically lasted about 10 to 15 min.

(26) TABLE-US-00001 TABLE 1 6T/6I 6T/6I 6T/6I Ingredients (60/40) (56/44) (52/48) Water (lb) 1333 1375 1280 HMD (lb) (90% solution) 430 444 414 TPA (lb) 331 318 276 IPA (lb) 220.5 250 254 Acetic acid (lb) 11.3 11.7 10.9 SHP (gr) 74 75.8 70.8 Carbowax 8000 (gr) (antifoam) 9.2 9.5 8.8 Reactor Conditions Cycle 2 end temperature (° C.) 300 290 280 Cycle C3A pressure ramp down rate 6 6 6 (psi/min) Cycle 3A final pressure (psia) 255 255 255 Cycle 3A minimum end temperature 305 295 285 (° C.) Cycle 3B pressure ramp down rate 8 8 8 (psi/min) Cycle 3B final pressure (psia) 55 55 55 Cycle 3B minimum end temperature 310 300 290 (° C.) Cycle 3C pressure ramp down rate 4 4 4 (psi/min) Cycle 3C final pressure (psia) 17 17 17 Cycle 3C minimum end temperature 315 305 295 (° C.) Cycle 4 final pressure (psia) 10.5 10.5 10.5 Cycle 4 ramp rate (psi/min) 0.5 0.5 0.5 Cycle 4 maximum temperature (° C.) 320 ± 2 310 ± 5 300 ± 5 Cycle 4 max time (min) 10-15 10-15 10-15
Synthesis of Semi-Aromatic Polyamide (A): 10T/1010 80/20

(27) The 10T/1010 semi-aromatic polyamide (A) used in examples E15 and E16 were prepared in a 12 L agitated autoclave in a one-step all melt batch process similar to the process used to prepare 6T/6I as described below. Amounts of ingredients and temperatures used are listed in Table 1A.

(28) A 12 L heatable autoclave equipped with a helical agitator was charged with all the ingredients listed in Table 1A. The autoclave was sealed and agitated at 5 RPM for 10 min under continuous nitrogen purge and then heated while stirring to 155° C. at a pressure of 55 psia for the evaporation cycle to provide a concentrated salt solution. The total evaporation time was 30 to 45 min.

(29) Pressure on the concentrated salt solution was increased in a first cycle from 55 psia to 200 psia over a time period of about 15 to 25 min. A pressure control valve was manipulated in a manner to achieve the desired pressure/temperature required for different cycles. The pressure was held constant at 200 psia in a second cycle while the temperature was increased from 155° C. to 230° C. at which point the pressure was gradually increased at 3.2 psi/min. to a final pressure of 345 psia. The temperature was also gradually increased during this time to a final temperature as indicated in table 1A. The total reaction time for the second cycle was 120-135 min. During the third cycle, the pressure and temperature were slowly dropped at 7.3 psi/min to atmospheric pressure. During the final (vacuum) cycle (cycle 4), agitator torque was used as an indication of the melt viscosity and molecular weight of polyamide resin (A) to terminate the final cycle and start casting. Vacuum cycle typically lasted about 20 min or until the target torque was reached.

(30) TABLE-US-00002 TABLE 1A 10T1010 Ingredients (gr) (80/20) Water (gr) 2510 1,10-Diaminodecane 1686 TPA 1269 Sebacic acid 386 Acetic acid 23 SHP 0.74 1% Carbowax 8000 solution (antifoam) 14.8 Reactor Conditions Cycle 2 end temperature (° C.) 290 Cycle C3 pressure ramp down rate 7.3 (psi/min) Cycle 4 final pressure (psia) 10 Cycle 4 maximum temperature (° C.) 315 ± 2 Cycle 4 max time (min) Max. 20 min or until desired torque of the agitator shaft is reached

(31) Synthesis of Semi-Aromatic Polyamide (A) 6T/66 (25/75)

(32) Semi-aromatic polyamide A (6T/66 25/75) was prepared by melt mixing 73.5 wt % commercial PA66 (DuPont Zytel® 101) and 26.5 wt % 6T oligomer in a 26 mm extruder, both fed through the main feed port, using the following conditions: melt temperature at the die was 368° C., throughput: 50 pph, screw RPM: 800. Physical properties of PA-6A are shown in table 1B.

(33) Table 1B shows physical properties of different semi-aromatic polyamides (A) used in the novel processes disclosed herein to prepare semi-aromatic polyamide (C).

(34) TABLE-US-00003 TABLE 1B PA-1A PA-2A PA-3A PA-4A PA-5A PA-6A 6T 60 52 56 52 25 6I 40 48 44 48 1010 20 10T 80 66 75 Properties IV 0.92.sup.1 0.96.sup.1 0.95.sup.1 0.90.sup.1 0.90.sup.2 0.96.sup.2 Amine Ends.sup.2 32 24 27 28 Not fully dissolved Carboxyl 120 93 112 98 Not fully Ends dissolved Capped 65 65 65 65 130 0 Ends MP.sup.4 (1.sup.st 296 289 288 288 279 252 heating) 292 MP.sup.4 (2.sup.nd 290 276 279 279 284 239 heating) 297 FP.sup.4 238 223 214 218 257 225 Concentrations are in mol % .sup.1in m-cresol .sup.2in sulfuric acid .sup.3in phenol-methanol .sup.4MP and FP determined by DSC at 350° C. maximum temperature with 1 min isothermal hold
Polyamide Oligomer (B): 6T

(35) Polyamide oligomer (B), 6T, used in examples E1 to E13, E14a, E14b, C1a, and C1b was prepared according to the following procedure.

(36) A 45-gallon salt reactor was charged with 33 kg of water, 11.4 kg of 70% hexamethylenediamine solution, 11.5 kg of terephthalic acid, 173 gr of 1% sodium hypophosphate solution, and 86 gr of 1% Carbowax 8000 solution and then heated to 90° C. at a pressure of 14.5 psig for 60 minutes while stirring the ingredients resulting in a clear solution of in-situ-formed nylon salts. The salt solution was then pumped to a plough reactor at atmospheric pressure. The plough reactor was equipped with a heating jacket, a plough mixer, and a high shear chopper. Hot oil from a hot oil skid was used to provide heat for evaporation and reaction through the plough reactor jacket. The oligomerization process in the plough reactor started by providing heat through the jacket while mixing by plough mixer and chopper. The autogenous pressure in the plough reactor was increased to 365 psia in about 4 hours. The plough reactor was vented at this point and temperature slowly increased from 220° C. to 245° C. in 2 hours. When temperature of the oligomer solution reached 245° C., the plough reactor pressure was ramped down in about 45 min to atmospheric pressure. This resulted in a phase transition in which the polyamide oligomer becomes the solid phase. The polyamide oligomer was cooled to 60° C. in about 2 hours and discharged from the plough reactor to provide polyamide oligomer (B) used in the examples. Tables 2A and 2B disclose the IV and amine end group concentration of various 6T polyamide oligomers (B) except for O-13B which is 10T.

(37) TABLE-US-00004 TABLE 2A Properties O-1B O-2B O-3B 0-4B O-5B O-6B O-7B A/D ratio 0.99 0.99 0.95 0.97 0.97 0.97 0.95 IV.sup.1 0.20 0.23 0.22 0.25 0.26 0.24 0.23 Amine Ends.sup.2 813 587 793 605 544 678 673 MP* (1.sup.st 365 369 365 366 369 368 366 heating) 375 374 MP* (2.sup.nd 355 360 354 362 360 358 358 heating) FP* 325 333 323 337 334 328 330 *MP and FP determined by DSC at 395° C. maximum temperature with 1 min isothermal hold .sup.198% sulfuric acid .sup.2hexafluoroisopropanol

(38) TABLE-US-00005 TABLE 2B Properties O-8B O-9B 0-10B O-11B O-12B O-13B O-14B 0-15B A/D ratio 0.93 0.90 0.23 0.25 0.23 0.97 0.95 IV.sup.1 0.23 0.27 0.90 1.2 0.51 0.25 0.26 Amine Ends.sup.2 802 694 656 N/A 694 555 MP* (1.sup.st 364 358 357 367 367 302 367 367 heating) 373 369 372 312 MP* (2.sup.nd 356 350 352 355 355 290 355 352 heating) 360 FP* 329 326 333 329 328 263 329 323 *MP and FP determined by DSC at 395° C. maximum temperature with 1 min isothermal hold .sup.198% sulfuric acid .sup.2hexafluoroisopropanol
Polyamide Oligomer (B): 10T

(39) Polyamide oligomer (B), 10T, was prepared according to the following procedure. Properties are listed in Table 2B as sample O-13B.

(40) A salt reactor was charged with 20 kg of water, 10.3 kg of 1,10-diaminodecane, 9.6 kg of terephthalic acid, 176 gm of 1% sodium hypophosphate solution, and 88 gm of 1% Carbowax 8000 solution. The mixture was heated to 80° C. at atmospheric pressure for 60 minutes while stirring the ingredients until the 1,10 diaminodecane was dissolved. The resulting slurry was pumped to the plough reactor at atmospheric pressure. The 10T salt was processed under the same conditions as the 6T oligomers to provide 10T oligomers in powder form. The amine ends of O-13B could not be accurately determined due to undissolved oligomer.

(41) Semi-Aromatic Polyamide (C)

(42) Novel semi-aromatic polyamides (C) disclosed herein and listed in tables 3A to 3C were prepared by the following process:

(43) The 6T/6I polymer with less than 0.5% moisture was fed through a loss-in-weight main feeder to the first barrel of a 26 mm co-rotating intermeshing twin screw extruder. The extruder consists of 14 barrels, two vent ports and one side feeding port. 6T oligomer with less than 0.5% moisture is fed through the side feeder at barrel 6 or through the main feeder along with semi-aromatic polyamide (A). The first vent port was located downstream of the main feeding port to remove moisture from the polymer at a vacuum of 21 mmHg and the second vent port was located downstream of oligomer side feeding port at a vacuum level of 21 mmHg to remove water generated from the amidation reaction. 6T oligomer feeding rate was adjusted to have the desired weight percent of 6T oligomer relative to semi-aromatic polyamide (A). The average barrel temperatures ranged from about 335 to about 355° C. and screw RPM ranged from 350 to 575 and were adjusted to have a semi-aromatic polyamide (C) melt temperature in the range of 380 to 385° C. at the exit die as measured by a hand held device. Depending on the size and throughput of the extruder, residence time within the extruder ranges from about 30 seconds to less than 1 minute. Semi-aromatic polyamide (C) was collected by extruding into a chilled water bath and pelletized.

(44) TABLE-US-00006 TABLE 3A E1 E2 E3 E4 E5 E6 E7 Polyamide PA-1A PA-2A PA-3A PA-2A PA-2A PA-2A PA-3A resin (A) 6T/6I (mol %) 60/40 52/48 56/44 52/48 52/48 52/48 56/44 Wt % A 87.5 73 79.5 73 73 73 79.5 Oligomer (B) O-3B O-3B O-4B O-4B O-2B O-5B O-5B Wt % B 12.5 27 20.5 27 27 27 20.5 Properties Polyamide 65/35 65/35 65/35 65/35 65/35 65/35 65/35 resin (C) (6T/6I) (mol %) IV.sup.1 1.08 1.12 1.08 1.08 0.98 1.04 1.01 Amine Ends.sup.2 27 40 31 33 28 30 31 Carboxyl 80 63 83 81 104 91 105 Ends Capped 57 47 52 47 47 47 52 Ends MP* (1.sup.st 317 332 329 335 330 336 329 heating) MP* (2.sup.nd 311 313 313 317 313 315 313 heating) FP* 270 277 271 271 272 278 272 *MP and FP determined by DSC at 350° C. maximum temperature with 3 min isothermal hold .sup.1m-cresol .sup.2phenol/methanol

(45) The results in Table 3A show the reproducibility of the processes disclosed herein and the use of different semi-aromatic polyamides (A) and polyamide oligomers (B) to arrive at semi-aromatic polyamides (C) having the same 65/35 molar ratio. Examples E1 to E2 use different molar ratios of 6T/6I for semi-aromatic polyamide (A), but different concentrations of polyamide oligomer (B), to prepare semi-aromatic polyamide (C) having a 6T/6I molar ratio of 65/35. Examples E4 to E6 use 52/48 molar ratios of 6T/6I for semi-aromatic polyamide (A) to prepare semi-aromatic polyamide (C) having a 6T/6I molar ratio of 65/35 by using different polyamide oligomers (B). Examples E3 and E7 start with semi-aromatic polyamide (A) having a 6T/6I molar ratio of 56/44 to arrive at semi-aromatic polyamide (C) having a 6T/6I molar ratio of 65/35.

(46) TABLE-US-00007 TABLE 3B E8 E9 E10 E11 E12 E13 Polyamide PA-2A PA-1A PA-2A PA-2A PA-2A PA-2A resin (A) 6T/6I (mol %) 52/48 60/40 52/48 52/48 52/48 52/48 Wt % A 83 73 67 61 61 73 Oligomer (B) 0-11B O-3B 0-11B O-12B O-9B O-14B Wt % B 17 27 33 39 39 27 Polyamide 60/40 71/29 68/32 71/29 71/29 65/35 resin (C) (6T/6I) (mol %) IV    0.86.sup.1    1.16.sup.2    1.09.sup.2    1.16.sup.2    1.12.sup.2    1.1.sup.2 Amine Ends  34.sup.3  38.sup.4  60.sup.4  70.sup.4  55.sup.4  41.sup.4 Carboxyl 86 ND ND ND ND 74 Ends Capped 54 47 43 39 39 47 Ends MP.sup.5 (1.sup.st 321  336  337  343  338  336  heating) MP.sup.5 (2.sup.nd 301  325  320  327  327  317  heating) FP.sup.5 255  287  278  288  285  276  .sup.1m-cresol .sup.2sulfuric acid .sup.3phenol/methanol .sup.4hexafluoroisopropanol .sup.5MP AND FP determined by DSC at 350° C. maximum temperature with 3 min isothermal hold

(47) The results in Table 3B show various semi-aromatic polyamides (C) having different molar ratios of 6T/6I which may be produced by the novel processes disclosed herein. Examples E9, E11, and E12 use different semi-aromatic polyamide (A) and different polyamide oligomers (B) to arrive at semi-aromatic polyamide (C) having the same 6T/6I molar ratio of 71/29 which is a relatively high molar concentration of 6T. Examples E10 and E13 provide semi-aromatic polyamides (C) having molar ratios of 68/32 and 65/35 respectively. Example E8 shows semi-aromatic polyamide (C) comprising 6T/6I (60/40 molar ratio) prepared from a semi-aromatic polyamide (A) having a 52/48 molar ratio of 6T/6I.

(48) Additionally, examples E1 to E13 were tested by DSC at 390° C. and there was only a single melting point observed for the first heating, indicating that reaction between semi-aromatic polyamide (A) and polyamide oligomer (B) had occurred.

(49) TABLE-US-00008 TABLE 3C E14a E14b C1a C1b Polyamide PA-2A PA-2A PA-2A PA-2A resin (A) 6T/6I (mol %) 52/48 52/48 52/48 52/48 Wt % A 73 73 73 73 Oligomer (B) O-14B O-14B 0-12B 0-12B Wt % B 27 27 27 27 Properties Polyamide 65/35 65/35 65/35 65/35 resin (C) (6T/6I) (mol %) IV.sup.1   1.1   1.1    0.98.sup.1    0.98.sup.1 Amine Ends.sup.2 41 41 50 50 Carboxyl 74 74 ND ND Ends Capped 47 47 47 47 Ends MP* (1.sup.st 336  337  295  292  heating) 368  MP* (2.sup.nd 317  301  289  303  heating) FP* 276  264  238  264  DSC* max. 350° C. 390° C. 350° C. 390° C. temp. *MP AND FP determined by DSC at maximum temperature indicated with 3 min isothermal hold .sup.1sulfuric acid .sup.2hexafluoroisopropanol

(50) Table 3C provides clear evidence that for polyamide oligomer (B) to react with semi-aromatic polyamide (A) to form semi-aromatic polyamide (C) in the processes disclosed herein, polyamide oligomer (B) must be at, preferably above, its melting point such that both semi-aromatic polyamide (A) and polyamide oligomer (B) are in the melt state. E14a and E14b in Table 3C represent a single polymer test sample which has been tested at two different maximum temperatures by DSC—350° C. and 390° C. C1a and C1 b represent a single polymer test sample which has also been tested by DSC at both 350° C. and 390° C.

(51) C1 and E14 in table 3C use the same semi-aromatic polyamide (A) and similar 6T polyamide oligomers (B) to prepare polyamides having the same 65/35 (6T/6I) molar ratios. The same extruder was used to prepare E14 and C1 except the temperatures in the extruder to prepare C1 were different than E14. For C1, polymer exit melt temperature was 355° C. which is above the mp of semi-aromatic polyamide (A) but below the melting point of polyamide oligomer (B) which is about 370° C. Under these extruder conditions, reaction of polyamide oligomer (B) with semi-aromatic polyamide (A) does not readily occur as reflected by the dual melting point (1st heating) of C1 b. The two first melting points of C1 b when tested at 390° C. is due to the presence of semi-aromatic polyamide (A) and unreacted polyamide oligomer (B) which have different melting points.

(52) When tested at 350° C. (C1a) the melting point of polyamide oligomer (B), which is about 370° C., is not reached due to the maximum test temperature of 350 C, resulting in a single melting peak for semi-aromatic polyamide (A).

(53) It should also be noted that when C1 is tested at 390° C., for the second heating, the dual melting points disappear and only a single melting point is present. This is due to the fact that semi-aromatic polyamide (A) and polyamide oligomer (B) reacted during testing resulting in semi-aromatic polyamide (C) having a melting point of 303° C.

(54) E14, when tested by DSC at both 350° C. (E14a) and 390° C. (E14b), exhibits a single melting point at both DSC test temperatures and for both heat cycles indicating that semi-aromatic polyamide (A) and polyamide oligomer (B) have reacted to form semi-aromatic polyamide (C).

(55) TABLE-US-00009 TABLE 3D E15 E16 E17 Polyamide 10T/1010 10T/1010 PA-6A resin (A) 10T/1010 80/20 80/20 — (mol %) Wt % A 75 75  59 Oligomer (B) 10T 10T O-15B Wt % B 25 25  41 Properties Polyamide 85/15 85/15 55/45 resin (C) (10T/1010) (10T/1010) (6T/66) (mol %) IV.sup.1 1.0 1.04    1.08.sup.3 Amine 47 44 ND.sup.4 Ends.sup.2 Carboxyl N/A N/A ND.sup.4 Ends Capped 97.5 97.5  0 Ends MP* (1.sup.st 299 286 337 heating) 287 298 MP* (2.sup.nd 289 288 322 heating) FP* 271 270 280 *mp determined by DSC at 350° C. maximum temperature with 3 min isothermal hold .sup.1m-cresol .sup.2hexafluoroisopropanol .sup.3sulfuric acid .sup.4Not Dissolved

(56) Table 3D shows various semi-aromatic polyamides (C) which are produced by the processes disclosed herein using 10T/1010 semi-aromatic polyamide (A) and 10T polyamide oligomer (B). The terephthalic acid content of semi-aromatic polyamide (A) is increased from 80 mol % to 85 mol % using the novel processes disclosed herein to provide semi-aromatic polyamides (C) as shown by E14 and E15.

(57) Polyamide PA-6A (59 wt %) was fed into an extruder with 6T oligomer O-15B (41 wt %), both fed through main feed port, under the following conditions to make semi-aromatic polyamide (C) E17: melt temperature at the die: 370° C., throughput: 50 pph, screw RPM: 500.

(58) TABLE-US-00010 TABLE 3E C2 C3 C4 PA 6T/6I 65/35 68/32 (mol %) PA 6T/66 55/45 (mol %) Properties IV     0.88.sup.1     0.84.sup.1     0.99.sup.1 Amine Ends  23.sup.2  25.sup.2  65.sup.2 Carboxyl  97 116  68 Ends Capped  40 105  65 Ends MP* (1.sup.st 315 326 312 heating) MP* (2.sup.nd 309 314 267 heating) FP* 244 271 304 *MP and FP determined by DSC at 350° C. maximum temperature with 1 min isothermal hold .sup.1m-cresol .sup.2phenol/methanol

(59) Table 3E shows the properties of 6T/6I and 6T/66 polyamides produced by an all melt continuous process as disclosed in U.S. Pat. No. 6,759,505. C2 has a 6T/6I molar ratio of 65/35 and a freezing point of 244° C., compared to 6T/6I polyamides having the same molar ratio of repeat units but which have been prepared by the novel processes disclosed herein (E1 to E7). The lowest freezing point of examples E1 to E7 is 270° C., which is 26° C. above the freezing point of C2.

(60) C3 has a 6T/6I molar ratio of 68/32 and a freezing point of 271° C., compared to E10 which has the same molar ratio of repeat units but which has been prepared by the novel processes disclosed herein. E10 has a freezing point of 278° C., which is 7° C. above the freezing point of C3. It should also be noted that as the molar concentration of terephthalic acid increases in the polyamide, the freezing point also increases as shown by C3.

(61) TABLE-US-00011 TABLE 3F C5 10T/1010 Properties 85/15 (mol %) IV     0.84.sup.1 Amine Ends  20.sup.2 Carboxyl Ends Capped Ends 140 MP* (1.sup.st 286 heating) 300 MP* (2.sup.nd 289 heating) FP* 262 *MP and FP determined by DSC at 350° C. maximum temperature with 1 min isothermal hold .sup.198% sulfuric acid .sup.2hexafluoroisopropanol

(62) C5 in table 3F is produced in an autoclave by an all melt batch process and has a freezing point of 262° C. compared to examples E15 and E16 which have the same 10T/1010 molar ratio as C6 (85/15) but which have been prepared by the processes disclosed herein. The freezing points of E15 and E16 are 271° C. and 270° C., respectively, which are at least 8° C. above the freezing point of C5.

(63) TABLE-US-00012 E1 C2 E10 C3 E15 C5 E17 C4 Polymer 6T/6I  6T/6I  6T/6I  6T/6I  .sup. 10T/1010 .sup. 10T/1010 6T/66 6T/66 mol % 65/35 65/35 68/32 68/32 85/15 85/15 .sup. 55/45 .sup. 55/45 MP.sup.1 (1.sup.st 317 315 337 326 299/287 299/286 335 312 heating) MP.sup.1 (2.sup.nd 305 309 320 314 289 289 322 304 heating) FP.sup.1 262 244 278 271 271 264 279 267 FP Δ* 18 7 7 12 *Difference between FP of example and comparative example .sup.1All MP and FP at 350° C. with 1 min isothermal hold

(64) Table 3G summaries the differences in freezing points between semi-aromatic polyamides prepared by the processes disclosed herein and all-melt continuous or batch processes. The semi-aromatic polyamides in comparative examples C2, C3, and C4 are prepared by all-melt continuous processes as disclosed in U.S. Pat. No. 6,759,505, example 3. C5 is produced by a batch process.

(65) As shown by table 3G, E1 and C2 have identical molar ratios of 6T/6I. E1 has the lowest FP of all the 65/35 examples at 269° C. and C2 has a FP of 244° C., a difference of 25° C. E10 and C3 have identical molar ratios of 6T/6I and prepared by different processes. E10 has a FP of 278° C. and C3 has a FP of 271° C., a difference of 7° C. A difference in FP's of 7° C. and 12° C. is shown between E15 and C5, and E17 and C4 respectively.

(66) These differences in freezing points is a clear indication of differences in chemical structure between semi-aromatic polyamides prepared by the processed disclosed herein and by existing all-melt continuous or batch processes.