THERMOPLASTIC MOULDING COMPOSITION CONTAINING POLYALKYLENE TEREPHTHALATE

Abstract

The present invention relates to a thermoplastic molding compound comprising a polyalkylene terephthalate and a polyimide, wherein the molding compound has a single glass transition temperature in DSC measurement. The present invention further relates to the use thereof and to fibers, films and shaped bodies produced from the molding compound.

Claims

1. A thermoplastic molding compound comprising a polyalkylene terephthalate and a polyimide, wherein the molding compound has a single glass transition temperature in DSC measurement, wherein the polyimide is obtained by reaction of at least one carboxylic dianhydride with at least one isocyanate, wherein the isocyanate comprises at least two isocyanate groups and wherein after the reaction of the at least one carboxylic dianhydride with the at least one isocyanate unconverted isocyanate groups were blocked with an alcohol or an amine and wherein the ratio of polyalkylene terephthalates are to polyimide is in the range from 1:1 to 9.9:1.

2. The thermoplastic molding compound according to claim 1, wherein the single glass transition temperature has a value of at least 45° C.

3. The thermoplastic molding compound according to claim 1, wherein the at least one carboxylic dianhydride is 1,2,4,5-benzenetetracarboxylic anhydride.

4. The thermoplastic molding compound according to claim 1, wherein the at least one isocyanate is 4,4′-diphenylmethane diisocyanate, oligomeric 4,4′-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, or a mixture thereof.

5. The thermoplastic molding compound according to claim 1, wherein a mixture of oligomeric 4,4′-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, and 2,6-Toluoldiisocyanat has been employed.

6. The thermoplastic molding compound according to claim 5, wherein the molar ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate is in the range from 1:1 to 10:1.

7. The thermoplastic molding compound according to claim 5, wherein the molar ratio of oligomeric 4,4′-diphenylmethane diisocyanate to the sum of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate is in the range from 1:1 to 0.1:1.

8. The thermoplastic molding compound according to claim 1, wherein after the reaction of the at least one carboxylic dianhydride with the at least one isocyanate, a reaction with an alcohol is carried out.

9. The thermoplastic molding compound according to claim 1, wherein the alcohol is tert-butanol.

10. The thermoplastic molding compound according to claim 1, wherein the polyimide has an isocyanate content of less than 1% by weight based on the total weight of the polyimide.

11. The thermoplastic molding compound according to claim 1, wherein the ratio of the weight fractions of polyalkylene terephthalate to polyimide is in the range from 2:1 to 9:1.

12. The thermoplastic molding compound according to claim 1, wherein the proportion of polyalkylene terephthalate based on the total weight of the molding compound is at least 50% by weight.

13. The thermoplastic molding compound according to claim 1, wherein reinforcing fibers, in particular glass fibers, are also present.

14. (canceled)

15. A fiber, film or shaped body produced from a thermoplastic molding compound according to claim 1.

16. (canceled)

17. The thermoplastic molding compound according to claim 1, wherein the polyalkylene terephthalate is polybutylene terephthalate.

18. The thermoplastic molding compound according to claim 1, wherein the polyimide is isocyanate-free.

Description

EXAMPLES

[0094] 1. Production of Polyimides

[0095] 1.1. Production of PMDI-MDI-PDA-tBuOH (PI-1)

[0096] Reagents and Reactants:

[0097] 42.00 g (0.192 mol) of 1,2,4,5-benzentetracarboxylic dianhydride (PDA)

[0098] 18.43 g (0.0275 mol) of Lupranat® M20 (oligomeric MDI, polyMDI, PMDI)

[0099] 6.88 g (0.0275 mol) of MDI

[0100] 29.47 g (0.398 mol) of tert-butanol

[0101] 144.2 ml of NMP

[0102] Reaction Procedure:

[0103] In a standard stirring apparatus comprising a 500 ml four-necked flask fitted with a dropping funnel, a Teflon stirrer, a reflux condenser and a thermometer, 1,2,4,5-benzentetracarboxylic dianhydride was dissolved in NMP at 80° C. with stirring. A mixture of Lupranat® M20 and MDI was added dropwise to the solution under a nitrogen atmosphere and the oil bath temperature was maintained at 80° C. A slightly exothermic reaction with evolution of gas was observable. The mixture was maintained at 80° C. for 3 hours with stirring.

[0104] After cooling of the reaction mixture to 50° C., tert-butanol was slowly added via the dropping funnel. The course of the reaction was monitored by IR measurement. After complete disappearance of the NCO band the solution was distilled at 80° C. under vacuum (20 mbar) to remove excess tert-butanol.

[0105] The polyimide solution was added dropwise to a water bath, thus causing the polyimide to precipitate as a yellow powder.

[0106] 1.2. Production of Further Polyimides

[0107] Further polyimides were produced by analogy to the production process at 1.1. The composition of all of the polyimides is apparent from the following table:

TABLE-US-00001 Polyimide Composition Proportions T.sub.g (° C.) PI-1 PMDI-MDI-PDA-.sup.tBuOH 0.5-0.5-3.5-excess 225 PI-2 PMDI-MDI-PDA-.sup.tBuOH 0.75-0.25-3.5-excess 238 PI-3 PMDI-TDI80*-PDA-.sup.tBuOH 0.4-0.6-3.5-excess 233 PI-4 PMDI-TDI80*-PDA-.sup.tBuOH 0.3-0.7-3.5-excess 219 PI-5 PMDI-TDI80*-PDA** 0.3-0.7-3.5 242 *TDI80 = (20:80 mixture of 2,6- and 2,4-toluene diisocyanate) **no addition of tert-butanol

[0108] 2. Production of Molding Materials

[0109] To produce the molding compounds (FM-1 to FM-5) mixtures of the polyimides with polybutylene terephthalate (Ultradur® B4500, PBT) were added to an Xplore MC 15 mini extruder in an amount of 15 g and mixed at a temperature of 260° C. to 300° C. at 80 rpm for 3 minutes. The obtained molding compounds showed a single T.sub.g value in DSC measurement. The mixing ratios and obtained T.sub.g values are summarized in the following table:

TABLE-US-00002 FM-1 FM-2 FM-3 FM-4 FM-5 PBT 100 75 75 89.4 75 PI-1 25 PI-2 25 PI-3 10.6 PI-4 25 T.sub.g (° C.) 39 64.9 59 50.2 82.5

[0110] As is apparent the addition of PI made it possible to markedly elevate the T.sub.g of polybutylene terephthalate.

[0111] To produce the molding compounds FM6 to FM9 the components were mixed in a ZSK 18 extruder at a barrel temperature of 260° C., a screw speed of 300 rpm and a throughput of 6 kg/h, pelletized and subsequently dried in a drying cabinet at 100° C. for 6 hours. The tensile bars were produced by injection molding at a melt temperature of 260° C. and a mold temperature of 60° C.

[0112] The obtained test specimens were tested at 23° C. according to ISO 527. The results obtained are summarized in the table that follows.

[0113] The glass fiber used was an E-glass fiber endowed with an epoxy size; staple fibers were employed.

TABLE-US-00003 FM-6 FM-7 FM-8 FM-9 PBT 70 59.5 56 52.5 PI-4 — 10.5 14 17.5 Glass fibers 30 30 30 30 Tg [° C.] 45 57 62 66 Modulus of 9170 9350 9400 9420 elasticity [MPa] Tear strength 124 134 136 134 [MPa]

[0114] The glass fiber-reinforced molding compounds exhibit not only an elevated glass transition temperature but surprisingly also higher stiffness and strength.