PROCESS FOR PREPARING A FLUID CONDUIT

Abstract

The invention relates to a process for preparing a fluid conduit comprising a mono-layer comprising a thermoplastic elastomer in an amount of at least 80 wt % with respect to the total weight of the mono-layer, comprising at least the 5 following steps: a. Melting a composition comprising at least a thermoplastic elastomer having a melt volume flow rate measured at 230 C. under a load of 10 kg (MVR 230 C./10 kg), according to IS01133 (2011) of at most 40 g/10 min and having a heat resistance of at least 250 hours at 175 C. at which the 10 elongation at break remains at least 100% as measured according to ISO 527 with a test speed of 50 mm/min; b. Forming a parison from the melt; c. Placing the parsion in a mold; d. Blow-up the parison against the mold; 15 e. Cooling down the mold, thereby obtaining the fluid conduit comprising the mono-layer. The invention also relates to a fluid conduit.

Claims

1. Process for preparing a fluid conduit comprising a mono-layer comprising a thermoplastic elastomer in an amount of at least 80 wt % with respect to the total weight of the mono-layer, comprising at least the following steps: a. Melting a composition comprising at least a thermoplastic elastomer having a melt volume flow rate measured at 230 C. under a load of 10 kg (MVR 230 C./10 kg), according to ISO1133 (2011) of at most 40 g/10 min and having a heat resistance of at least 250 hours at 175 C. at which the elongation at break remains at least 100% as measured according to ISO 527 with a test speed of 50 mm/min; b. Forming a parison from the melt; c. Placing the parsion in a mold; d. Blow-up the parison against the mold; e. Cooling down the mold, thereby obtaining the fluid conduit comprising the mono-layer.

2. Process according to claim 2 wherein in step c) the parison is placed in a mold by drawing the parison through the mold by reduced pressure or by clamping the parison in a mold.

3. Process according to claim 1, wherein the thermoplastic elastomer is a block copolymer elastomer comprising hard and soft segments.

4. Process according to claim 3, wherein the block copolymer elastomer comprises hard segments (a) chosen from the group consisting of polyester, polyamide and polyurethane and soft segments (b) chosen from the group consisting of aliphatic polyether, aliphatic polyester and aliphatic polycarbonate.

5. Process according to claim 3, wherein the soft segment is an aliphatic polycarbonate and is made up of repeating units from at least one alkylene carbonate

6. Process according to claim 5, wherein the alkylene carbonate repeating unit is represented by the formula: ##STR00005## where R=H and/or alkyl, and X=2-20.

7. Process according to claim 6, wherein R=H and X=6.

8. Process according to claim 3, wherein the hard segment is a polyester.

9. Process according to claim 1 above, wherein the mono-layer comprises at least 90 wt % of thermoplastic elastomer with respect to the total weight of the mono-layer.

10. Fluid conduit comprising a mono-layer comprising a thermoplastic elastomer in an amount of at least 80 wt % with respect to the total weight of the mono-layer, wherein the fluid conduit has a heat resistance of at least 250 hours at 175 C. at which the elongation at break remains at least 100% as measured according to ISO 527 with a test speed of 50 mm/min and wherein the thermoplastic elastomer has a melt volume flow rate measured at 230 C. under a load of 10 kg (MVR 230 C./10 kg), according to ISO1133 (2011) of at most 40 g/10 min.

11. Fluid conduit obtainable by the process according to claim 1.

12. Fluid conduit according to claim 10, being a hot charge air duct or a clean air duct.

Description

EXAMPLES

Test Methods:

[0061] The melting temperature was measured with DSC, according to ISO 11357-1:1997 under air atmosphere (purge 50 ml/min) using a heating and cooling rate of 20 K/min.

[0062] The melt volume flow rate (MVR) was measured according to ISO 1133 (2011) at 230 C. under a load of 10 kg.

[0063] Elongation at break of the materials were measured at a specific temperature on tensile bars type 1BA, punched out from an injection moulded plate perpendicular to the flow direction of moulding, according to ISO 527 with a test speed of 50 mm/min (150527-2/1BA/50). Elongation at break of fluid conduits were measured at a specific temperature on tensile bars type 1BA cut from the fluid conduit.

[0064] Heat resistance is defined as the time until which the elongation at break remains above 100%.

[0065] Modulus was measured by a Dynamic Mechanical Spectrometer (DMS) on a test-sample that was dynamically elongated at a temperature range at a frequency of 1 Hz, following ASTM D5026. The values are provided at a temperature of 160 C.

[0066] Hardness according to Shore D was measured at room temperature with a method following the instructions of ISO 868.

[0067] Test samples were prepared by injection molding a plate of the material of 2 mm thick. Subsequently a test bar (type1BA) was punched out of the injection molded plate, perpendicular to the flow direction during molding. These test bars represent the material as present in a fluid conduit prepared by the process according to the invention.

Materials Used

[0068] Material 1 is a block copolyester elastomer of hardness shore D 61, modulus at 160 C. of 71 MPa, MVR (230 C., 10 kg) of 22.7 and melting point of 211 C., based on 72 wt % polybutylene terephthalate hard blocks and 28 wt % hexamethylene carbonate soft blocks. Elongation at break (%) during ageing at 175 C. is given in Table 1.

[0069] Material 2 is a block copolyester elastomer of hardness shore D 52, modulus at 160 C. of 35 MPa, MVR (230, 10 kg) of 14.5 and melting point of 205 C., based on 65% polybutylene terephthalate hard blocks and 35% hexamethylene carbonate soft blocks.

[0070] Material 3 is a block copolyester elastomer of hardness shore D 55, modulus at 160 C. of 42 MPa, MVR (230 C., 2.16 kg) of 8.6 and melting point of 206 C., based on 64.8 wt % polybutylene terephthalate hard blocks and 35.2 wt % Poly Butylene Adipate soft blocks. Elongation at break (%) during ageing at 175 C. is given in Table the table 1.

[0071] Material A is a block copolyester elastomer of hardness shore D 55, modulus at 160 C. of 86 MPa, MVR (230 C., 10 kg) of 2.9 and melting point of 220 C., based on 70 wt % polybutylene terephthalate hard blocks and 30wt % ethylene oxide-terminated poly(propylene oxide)diol, comprising about 30 mass % of ethylene oxide soft blocks. Elongation at break during ageing @175 C. was measured and is present in Table 2.

[0072] Material B is a block copolyester elastomer of hardness shore D 50, modulus at 160 C. of 30 MPa, MVR (230 C., 10 kg) of 2 and melting point of 202 C., based on 67.5wt % polybutylene terephthalate hard blocks and 32.5wt % ethylene oxide-terminated poly(propylene oxide)diol, comprising about 30 mass % of ethylene oxide soft blocks. Elongation at break during ageing @175 C. was measured and is present in Table 2.

[0073] Material C (Hytrel 4275) comprises a block copolyester elastomer of hardness shore D 52, modulus at 160 C. of 23 MPa, MVR(230 C., 10kg) of 6 and melting point of 192 C., based on 64 wt % polybutylene terephthalate hard blocks and 36 wt % polytetrahydrofuran soft block. Elongation at break during ageing @165 C. was measured and is present in Table 3.

[0074] Material D (Hytrel 8441) comprises a block copolyester elastomer of hardness shore D 52, modulus at 160 C. of 41 MPa, MVR(230 C., 10 kg) of 10 and melting point of 211 C. based on 66 wt % polybutylene terephthalate hard blocks and 34 wt % ethylene oxide-terminated poly(propylene oxide)diol, comprising about 30 mass % of ethylene oxide soft blocks. Elongation at break during ageing @165 C. was measured and is present in Table 3.

[0075] Material E (Hytrel 8797) comprises a block copolyester elastomer, modulus at 160 C. of 41 MPa, melting point of 215 C., which copolyester elastomer is based on 66 wt % polybutylene terephthalate hard blocks and 34 wt % ethylene oxide-terminated poly(propylene oxide)diol, comprising about 30 mass % of ethylene oxide soft blocks. Elongation at break during ageing @165 C. was measured and is present in Table 3.

TABLE-US-00001 TABLE 1 Elongation at break at 175 C.; materials for a fluid conduit according to the invention Time (hrs) Material 1 Material 2 Material 3 0 639 650 650 250 504 646 300 480 500 398 414 415 2000 216 280 2135 230 3000 68 193 150

[0076] Material 1 thus has a heat resistance at 175 C. of at least 2500 hours and material 2 has a heat resistance of more than 3000 hours. Material 3 has a heat resistance of more than 3000 hours.

TABLE-US-00002 TABLE 2 Comparative data Elongation at break at 175 C. Time (hrs) Material A Material B 0 640 670 24 551 537 100 376 297 250 6 7

[0077] Both material A and B showed a heat resistance of less than 250 hours and are thus unsuitable for a fluid conduit according to the invention.

TABLE-US-00003 TABLE 3 Comparative data Elongation at break at @ 165 C.: Time (hrs) Material C Material D Material E 0 622 532 527 200 81 23 327 500 0 0 0

[0078] The heat resistance of material C, D and E was measured at 165 C. At this temperature the time to reach 100% elongation at break was below 200 hrs for C and D and between 200 and 500 hours for E. This means that at 175 C. the heat resistance performance of material C and D will be even shorter, i.e. the time to reach 100% elongation at break will be shorter than 200 hrs.

[0079] The decrease in elongation at break of material E at 165 C. was very similar to the decrease of elongation at break of materials A and B. Since materials A and B have a heat resistance (time to reach 100% elongation at break) at 175 C. shorter than 250 hrs, the heat resistance of material E (time to reach 100% elongation at break) at 175 C. is also shorter than 250 hrs.

[0080] Surprisingly, material 1 and 2 and 3 exhibited a high heat resistance in combination with an MFI of at most 40, which makes these materials highly suitable for blow molding of a fluid conduit. Comparative material A and B clearly showed a much lower heat resistance, which makes them unsuitable for application in a fluid conduit for high temperature applications. Also comparative materials C to E did not show a sufficient heat resistance.

[0081] Air ducts were prepared by blow molding material 1 and 2. Similar heat resistance was observed for these air ducts, when a test bar type 1BA was cut from the air duct and elongation at break was measured at a temperature of 175 C.