A PROCESS FOR THE PRODUCTION OF A MOULDED ARTICLE

Abstract

Disclosed herein is a process for the production of a moulded article (MA). Additionally disclosed herein is a method of using at least one blowing gas (C) in the production of a moulded article (MA) for reducing the warpage of the moulded article (MA), where the moulded article (MA) includes at least one thermoplastic polymer (A) and at least one reinforcing fibre (B). Further disclosed herein is the moulded article (MA) obtained by the process.

Claims

1. A process for the production of a moulded article (MA) comprising the following steps a) to d) of a) providing a flowable composition (FC) comprising at least the following components (A) to (C) (A) at least one thermoplastic polymer, (B) at least one reinforcing fibre and (C) at least one blowing gas, b) injecting the flowable composition (FC) provided in step a) into a mould at a first pressure (p.sub.1), c) cooling the flowable composition (FC) injected in step b) at a holding pressure (p.sub.2), wherein the holding pressure (p.sub.2) is lower than the first pressure (p.sub.1), to obtain the moulded article (MA), and d) removing the moulded article (MA) from the mould, wherein the at least one thermoplastic polymer (A) is selected from the group consisting of polyamide 6 (PA 6), polyamide 66 (PA 66), polyamide 6/66 (PA 6/66), polyamide 66/6 (PA 66/6), polyamide 610 (PA 610), polyamide 6/6T (PA 6/6T), polyamide 6T/6I (PA 6T/6I), polyamide 12 (PA12), polyamide 4T (PA 4T), polyamide 9T (PA 9T), polyamide 46 (PA 46), polyamide 1010 (PA1010) and polyamide 1212 (PA1212), wherein, in step b), the first pressure (p1) is in the range from 1000 to 2000 bar, and, in step c), the holding pressure (p2) is in the range from 600 to 1300 bar.

2. The process according to claim 1, wherein the moulded article (MA) obtained in step c) comprises less of the at least one blowing gas (C) than the flowable composition (FC) provided in step a).

3. The process according to claim 1, wherein, in step b), the flowable composition (FC) is injected at a temperature in the range from 150 to 400° C. into the mould.

4. The process according to claim 1, wherein the mould into which the flowable composition (FC) is injected in step b) has a temperature T.sub.M in the range from 20 to 120° C.

5. The process according to claim 1, wherein the at least one thermoplastic polymer (A) is selected from the group consisting of polyamides, polyesters, polycarbonates, polyolefins, polyurethanes, polyethers, polysulfones, polymethacrylates, polystyrenes and polyoxymethylene.

6. The process according to claim 1, wherein the at least one reinforcing fibre (B) is selected from the group consisting of natural fibres, basalt fibres, aramid fibres, glass fibres and carbon fibres.

7. The process according to claim 1, wherein the at least one reinforcing fibre (B) is selected from the group consisting of glass fibres, wherein the ratio of the length of the glass fibres to the diameter of the glass fibres is in the range from 20:1 to 30:1.

8. The process according to claim 1, wherein the at least one blowing gas (C) is selected from the group consisting of nitrogen, carbon dioxide and carbon monoxide.

9. The process according to claim 1, wherein, in step a), the flowable composition (FC) comprises in the range from 0.01 to 10% by volume of the at least one blowing gas (C), based on the total volume of the flowable composition (FC).

10. The process according to claim 1, wherein the flowable composition (FC) is provided by compounding a polymer composition (PC) comprising at least the following components (A), (B) and (C*) (A) at least one thermoplastic polymer, (B) at least one reinforcing fibre and (C*) at least one blowing agent, in an extruder, wherein the at least one blowing agent (C*) is decomposed to obtain the at least one blowing gas (C), to obtain the flowable composition (FC) comprising at least the components (A) to (C).

11. The process according to claim 10, wherein the at least one blowing agent (C*) is selected from the group consisting of gas-releasing polymers, gas-releasing additives and mixtures therefrom.

12. The process according to claim 10, wherein the polymer composition (PC) comprises in the range from 35 to 99.98% by weight of component (A), in the range from 0.01 to 60% by weight of component (B) and from 0.01 to 5% by weight of component (C*), based in each case on the total weight of the polymer composition (PC).

13. The process according to claim 1, wherein the flowable composition (FC) further comprises at least one carbon black (D).

14. The process according to claim 1, wherein the flowable composition (FC) comprises at least one further additive (E) selected from the group consisting of stabilizers, dyes, pigments, impact modifiers, flame retardants and plasticizers.

15. A method of using at least one blowing gas (C) in the process for the production of a moulded article (MA) according to claim 1, the method comprising using the at least one blowing gas (C) for reducing the warpage of the moulded article (MA), wherein the moulded article (MA) comprises at least one thermoplastic polymer (A) and at least one reinforcing fibre (B).

16. A moulded article (MA) obtained by a process according to claim 1.

17. (canceled)

18. (canceled)

19. (canceled)

20. The process according to claim 1, wherein the moulded article (MA) obtained in step c) comprises in the range from 0 to 3% by volume of the at least one blowing gas (C), based on the total volume of the moulded article (MA).

Description

EXAMPLES

[0174] The following components were employed:

Thermoplastic Polymer (A):

[0175] (A1) Polyamide 6 (PA 6) (Ultramid® B27E; BASF SE)

Reinforcing Fibre (B):

[0176] (B1) Glass Fibre (ECS 03 T-249H; Nippon Electric Glass)

Blowing Agent (C):

[0177] (C1) Styrene-maleic-anhydride-copolymer (SMA® 3000; Cray Valley)

Carbon Black (D):

[0178] (D1) Ensaco® 250G (Imerys Graphite & Carbon Switzerland Ltd.)

Additives (E):

[0179] (E1) N,N′-Ethylenebis(stearamide) [0180] (E2) Masterbatch comprising CuI and KI

[0181] Table 1 states the essential parameters of the thermoplastic polymer used (component (A)).

TABLE-US-00003 TABLE 1 Zero shear rate AEG CEG T.sub.M T.sub.G viscosity η.sub.0 at Type [mmol/kg] [mmol/kg] [° C.] [° C.] 240° C. [Pas] (A1) PA 6 36 54 220.0 53 399

[0182] AEG indicates the amino end group concentration. This is determined by means of titration. For determination of the amino end group concentration (AEG), 1 g of the component (thermoplastic polymer) was dissolved in 30 mL of a phenol/methanol mixture (volume ratio of phenol:methanol 75:25) and then subjected to potentiometric titration with 0.2 N hydrochloric acid in water.

[0183] The CEG indicates the carboxyl end group concentration. This is determined by means of titration. For determination of the carboxyl end group concentration (CEG), 1 g of the component (thermoplastic polymer) was dissolved in 30 mL of benzyl alcohol. This was followed by visual titration at 120° C. with 0.05 N potassium hydroxide solution in water.

[0184] The melting temperature (T.sub.M) of the thermoplastic polymer and the glass transition temperature (T.sub.G) were each determined by means of differential scanning calorimetry.

[0185] For determination of the melting temperature (T.sub.M), a first heating run (H1) at a heating rate of 20 K/min was measured. The melting temperature (T.sub.M) then corresponded to the temperature at the maximum of the melting peak of the heating run (H1).

[0186] For determination of the glass transition temperature (T.sub.G), after the first heating run (H1), a cooling run (C1) and subsequently a second heating run (H2) were measured. The cooling run was measured at a cooling rate of 20 K/min; the first heating run (H1) and the second heating run (H2) were measured at a heating rate of 20 K/min. The glass transition temperature (T.sub.G) was then determined at half the step height of the second heating run (H2).

[0187] The zero shear rate viscosity η.sub.0 was determined with a “DHR-1” rotary viscometer from TA Instruments and a plate-plate geometry with a diameter of 25 mm and a plate separation of 1 mm. Unequilibrated samples were dried at 80° C. under reduced pressure for 7 days and these were then analysed with a time-dependent frequency sweep (sequence test) with an angular frequency range of 500 to 0.5 rad/s. The following further analysis parameters were used: deformation: 1.0%, analysis temperature: 240° C., analysis time: 20 min, preheating time after sample preparation: 1.5 min.

Production of a Carbon Black Masterbatch (MB1)

[0188] The components reported in table 2 were compounded in the ratio reported in table 2 in a twin-screw extruder (ZE25A UXTI) at 280 rpm, a barrel temperature of 260° C. and a throughput of 11.2 kg/h with subsequent extrudate pelletization.

TABLE-US-00004 TABLE 2 Example (A1) [wt %] (D1) [wt %] (MB1) 70 30

Provision of the Flowable Composition (FC)

[0189] The components reported in table 3 were compounded in the ratio reported in table 3 in a twin-screw extruder (ZE25A UXTI) at 280 rpm, a barrel temperature of 260° C. and a throughput of 11.2 kg/h.

TABLE-US-00005 TABLE 3 Example E1 E2 C3 (A1) [wt %] 61.34 61.34 62.34 (B1) [wt %] 35 35 35 (C1) [wt %] 1 1 — (MB1) [wt %] 1.67 1.67 1.67 (E1) [wt %] 0.3 0.3 0.3 (E2) [wt %] 0.69 0.69 0.69

Production of Moulded Parts

[0190] The above provided flowable composition (FC) is then injection-moulded on an injection moulding machine to give moulded parts of a thickness of 2 mm, and of dimensions of 60×60 mm. The melt temperature in the inventive example E1 as well as in the comparative example C3 was 300° C. at 280 rpm, and in the inventive example E2 280° C. at 180 rpm. The flowable composition (FC) is injected at a first pressure (p.sub.1). The flowable composition is then cooled at a holding pressure (p.sub.2) to obtain the moulded article (MA), and the moulded article (MA) is removed from the mould. The first pressure (p.sub.1) and the holding pressure (p.sub.2) for the inventive examples E1 and E2, as well as for the comparative example C3, are listed in table 4.

TABLE-US-00006 TABLE 4 Example E1 E2 C3 first pressure (p.sub.1) [bar] 1300 1329 697 holding pressure (p.sub.2) [bar] 938 940 632

[0191] Subsequently, the properties of the moulded parts obtained were determined. The moulded parts obtained were tested in the dry state after drying at 80° C. for 336 h under reduced pressure. The results are shown in table 5. In addition, Charpy specimen were produced, which were likewise tested under dry conditions (according to ISO179-2/1eU: 1997+Amd.1:2011).

[0192] Tensile strength, tensile modulus of elasticity and elongation at break were determined according to ISO 527-1:2012.

[0193] The shrinkage was determined according to ISO 294.

TABLE-US-00007 TABLE 5 Example E1 E2 C3 Parallel Shrinkage [%] 0.61 0.72 0.27 Perpendicular Shrinkage [%] 1.02 1.07 0.88 Perpendicular Shrinkage/ <2 <1.5 >3 Parallel Shrinkage Tensile modulus of 11400 11090 elasticity [MPa] Tensile strength [MPa] 170 177 Elongation at break [%] 3.9 3.0 Charpy impact resistance, 98 82 unnotched [kJ/m.sup.2]

[0194] It is clearly apparent from table 5 that by the use of the at least one blowing gas (C) in the production of the moulded article (MA), wherein the moulded article (MA) comprises at least one thermoplastic polymer (A) and at least one reinforcing fibre (B), especially the parallel shrinkage of the moulded article (MA) is increased and, therefore, a reduced warpage of the moulded article (MA) is achieved. The moulded articles also show, despite the high shrinkage, good mechanical properties like a high tensile modulus of elasticity and a high tensile strength.