POLYESTER FOR PROFILE EXTRUSION AND/OR PIPE EXTRUSION

Abstract

Thermoplastic molding compositions containing A) from 29 to 99.99% by weight of a polyester, B) from 0.01 to 10% by weight of an ionomer composed of at least one copolymer of B.sub.1) from 30 to 99.9% by weight of ethylene B.sub.2) from 0 to 60% by weight of 1-octene or 1-butene or propylene or a mixture of these and B.sub.3) from 0.01 to 70% by weight of functional monomers, where the functional monomers are selected from the group of the carboxylic acid groups, carboxylic anhydride groups, carboxylic ester groups and mixtures of these, where component B) has been neutralized to an extent of at least 20% with alkali metal ions, based on 100% by weight of A) and B), and C) from 0 to 70% by weight of other additional substances, where the sum of the % by weight values for A) to C) is 100%, for use in the production of cable sheathing or optical-conductor sheathing via blow molding, profile extrusion, and/or pipe extrusion.

Claims

1. A thermoplastic molding composition comprising, as essential components, A) from 29 to 99.99% by weight of a polyester, B) from 0.01 to 10% by weight of an ionomer composed of at least one copolymer of B.sub.1) from 30 to 99.9% by weight of ethylene B.sub.2) from 0 to 60% by weight of 1-octene or 1-butene or propylene or a mixture of these, and B.sub.3) from 0.01 to 70% by weight of functional monomers, where the functional monomers are selected from the group of the carboxylic acid groups, carboxylic anhydride groups, carboxylic ester groups, and mixtures of these, where component B) has been neutralized to an extent of at least 20% with alkali metal ions, based on 100% by weight of A) and B), and C) from 0 to 70% by weight of other additional substances, where the sum of the % by weight values for A) to C) is 100%, for use in the production of cable sheathing or optical-conductor sheathing via blow molding, profile extrusion, and/or pipe extrusion.

2. The composition for use according to claim 1, where the alkali metal of component B) comprises sodium or potassium or of a mixture of these.

3. The composition for use according to claim 1, where the intrinsic viscosity (IV) of component A) in accordance with ISO 1628 is at least 140 ml/g.

4. The composition for use according to claim 1, where the carboxy end group content of component A) is from 10 to 50 meq/kg of polyester.

5. The composition for use according to claim 1, where component B) has been neutralized to an extent of at least 50%.

6. The composition for use according to claim 1, where component B.sub.3) comprises an ethylenically unsaturated mono- or dicarboxylic acid or of a functional derivative of such an acid.

7. The composition for use according to claim 1, where component B.sub.3) comprises acrylic acid, methacrylic acid, maleic anhydride, maleic acid, or fumaric acid, or of a (meth)acrylate having from 1 to 18 C atoms.

8. The use according to claim 1, where component B) comprises B.sub.1) from 35 to 89.95% by weight of ethylene B.sub.2) from 10 to 60% by weight of 1-octene or 1-butene or propylene or a mixture of these and B.sub.3) from 0.05 to 50% by weight of functional monomers according to claim 1.

9. The composition for use according to claim 1, where component B) comprises B.sub.1) from 50 to 98% by weight of ethylene B.sub.2) from 0 to 50% by weight of 1-octene or 1-butene or propylene or a mixture of these and B.sub.3) from 2 to 50% by weight of functional monomers according to claim 1.

10. A cable sheathing or optical-conductor sheathing obtained according to the thermoplastic molding composition according to claim 1.

Description

EXAMPLES

[0180] Component A:

[0181] Polybutylene terephthalate with viscosity 160 ml/g and carboxy end group content 34 meq/kg+(Ultradur B 6550 from BASF SE) (IV measured in 0.5% by weight solution in phenol/o-dichlorobenzene, 1:1 mixture, at 25 C. in accordance with ISO 1628), with melt volume rate MVR 9.5 cm.sup.3/10 min (measured in accordance with ISO 1133 at 250 C. with 2.16 kg load).

[0182] Component B/1

[0183] AClyn 285 P from Honeywell International Inc.:

[0184] An ionomer of an ethylene-acrylic acid copolymer which has been neutralized to an extent of 80% with sodium ions. Acrylic acid content is 15%.

[0185] Component B/2

[0186] A maleic anhydride-diisobutylene copolymer with molar mass 12 000 g/mol (determined by GPC). The product has been partially neutralized (75%) with NaOH, and its pH in aqueous solution is 11.5.

[0187] Component C/1

[0188] Talc

[0189] Component C/2

[0190] Ca stearate

[0191] Component B1comp

[0192] Sodium Carbonate

[0193] The molding compositions were produced in a ZSK25 with flat temperature profile at from 260 to 275 C. and subsequent pelletization. Metering of the additives was achieved here together with the pellets in the cold feed system.

TABLE-US-00001 TABLE 1 Compositions Component comp1 comp2 Ex. (1) Ex. (2) Ex. (3) Ex. (4) [% by wt.] [% by wt.] [% by wt.] [% by wt.] [% by wt.] [% by wt.] [% by wt.] A 99.9 99.6 99 97 99 97 B/1 1 3 B/2 1 3 B1comp 0.4 C/1 0.02 C/2 0.04

TABLE-US-00002 TABLE 2 Increase of melt stiffness/shear viscosity by means of additive-modification: Melt volume rate [250 C./2.16 kg] Unit comp1 comp2 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Retention time 4 min cm.sup.3/10 min 31.6 13.6 18.6 10.8 19.1 7.5 Retention time 10 min cm.sup.3/10 min 35.6 13.9 18.2 8.1 19.0 5.7 Retention time 20 min cm.sup.3/10 min 41.5 15.8 18.4 6.3 20.7 4.8 Retention time 30 min cm.sup.3/10 min 48.2 18 21.8 6.3 23.2 4.9

[0194] The examples in table 2 illustrate the improved melt stiffness when the salts of the invention are added, in comparison with the polyester not using additive-modification in the invention. In the case of the polyester not using additive-modification, the melt volume rate increases with prolonged retention time as a result of polymer degradation, whereas in the case of the samples using additive-modification the melt flow rate (determined in accordance with ISO 1133) remains constant, this possibly being attributable to the formation of a microstructure. This effect is particularly distinctly discernible in Ex (1). Specifically, greatly reduced melt flow and therefore increased melt strength can be observed at an elevated concentration (3%) of the additives 1/2. The increased stiffness of the melt permits stable conduct of the process during extrusion, resulting in very homogeneous thickness of the cable sheathing and low ovality.

TABLE-US-00003 TABLE 3 Increase of recrystallization temperature through additive-modification Recrystallization Unit A comp1 comp2 Ex. (1) Ex. (2) Ex. (3) Ex. (4) T.sub.pc C. 176.7 196.2 198 196.3 200.1 196.1 198.3

[0195] Table 3 shows calorimetric investigations by means of DSC in accordance with ISO 11357, heating and cooling rate 20 K/min. The peak crystallization temperature T.sub.pc was determined in the first cooling procedure. The examples in table 3 illustrate recrystallization at elevated temperature on addition of the salts of the invention, in comparison with the polyester not using additive-modification. A very sharp increase can already be discerned with the talc-nucleated material. A further increase of from 2.1 to 3.9 C. relative to the comparative example comp1 can be observed for the compounded materials of the invention with 3% loading.

[0196] I. Production of Optical-Conductor Sheathing Using Additive-Modification

[0197] Additive-modification of the polybutylene terephthalate by means of compounding results in reduced molecular weight. The additive-modified optical-conductor sheathing was produced by the process of the invention by way of additive concentrates. The concentrates were produced in a twin-screw extruder with 25 mm screw diameter (see table 4). Metering of the additives was achieved here together with the pellets in the cold feed system. In another step, the concentrates were mixed in a mixer with high-viscosity polymer pellets not subjected to additive-modification. It was thus possible in the subsequent processing step to obtain optical-conductor sheathing with high-molecular-weight polybutylene terephthalate.

TABLE-US-00004 TABLE 4 Production of concentrates Conc. (1) Conc. (2) Component [% by wt.] [% by wt.] A 95 79.94 B1comp 5 B/1 20

[0198] Concentrate 2 also comprised 0.02% of C/1 and 0.04% of C/2.

[0199] Production of the Pellet Mixtures of the Invention:

[0200] The mixtures were produced in the form of pellets/pellet mixtures in a tumbling mixer.

TABLE-US-00005 TABLE 5 Composition of the cable sheathing of the invention Component [% by wt.] C1 C2 C3 A 99.94 91.94 84.94 C/1 0.02 0.02 0.02 C/2 0.04 0.04 0.04 Conc (1) 8 Conc (2) 15

[0201] Production of Sheathed Optical-Conductor Cables:

[0202] The further processing of these pellet mixtures was achieved by means of a single-screw extruder with annular die. The production of such sheathing is described by way of example in the following document: H. J. Mair; Kunststoffe in der Kabeltechnik [Plastics in cable technology], chapter 9, Expertverlag 1983.

[0203] A 60 mm (L/D=24) Maillefer single-screw extruder was used. The line speed achieved during processing was 300 m/min.

TABLE-US-00006 TABLE 6 TEMPERATURE PROFILE DURING PROCESSING Zone Feed Zone Zone Zone Zone Water Water zone 1 2 3 4 Adapter Head Head trough 1 trough 1 Temperature [ C.] 210 275 275 275 275 275 275 275 55 18

[0204] During the production of the cable, a gel (jelly) (trade name: Unigel 400), the temperature of which was controlled to 80 C., was introduced between cable and sheathing. The sheathing procedure here was carried out with 12 glass-fiber conductors as core. The internal and external diameter of the glass-fiber cable sheathing can be found in table 5.

[0205] During the production of the cable C2, very significant formation of deposits could be observed on the annular die after only a short time; this did not occur in the case of the cable C3 of the invention.

[0206] 1.1. Characterization of the Cable Sheathing

[0207] The additive-modified cable sheathing of the invention exhibited substantially higher compressive strength (FIG. 1) than the prior art. Compressive strength was determined by means of a Zwick tester and pressure plate of length 80 mm, after removal of the optical conductor.

[0208] The substantially improved mechanical properties of the cable sheathing of the invention are also discernible in the tensile test, e.g. in substantially increased yield stress (FIG. 2). The tensile test was carried out with a Zwick Z050/BTC-FR050THA1 K in accordance with DIN EN ISO 527-1/-2 after removal of the optical conductor from the sheathing.

[0209] The experiments presented also revealed that, in comparison with the prior art, the formulations of the invention: [0210] I. exhibit increased mechanical protective effect versus (e.g. U.S. Pat. No. 6,262,185B1) [0211] II. exhibit substantially improved processability (no deposit on the annular die) versus WO2014146912A1.