Patent ID: 12214548

EXAMPLES

The following components are used:Semicrystalline polyamide (component (A)):

(P1)nylon-6 (Ultramid ® B27, BASF SE)Amorphous polyamide (component (B)):

(AP1)nylon-6I/6T (Grivory G16, EMS), with a molar ratio 6I:6T of1.9:1Amorphous polymer (component (C)):

(HP1)polysulfone (Ultrason S2010, BASF SE)(HP2)styrene-N-phenylmaleimide-maleic anhydride copolymer(Denka IP MS-NB, Denka)Additive:

(A1)Irganox 1098 (N,N′-hexane-1,6-diylbis(3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)), BASF SE)(A2)polyhydroxy ether-thermoplastic-thermoset resin (Phenoxy Resin,InChem)

Table 1 states the essential parameters of the semicrystalline polyamides used (component (A)), table 2 states essential parameters of the amorphous polyamides used (component (B)), and tables 3 states essential parameters of the amorphous polymers used (component (C)).

TABLE 1Zero shearrate viscosityAEGCEGTMTGη0at 240° C.Type[mmol/kg][mmol/kg][° C.][° C.][Pas]P1PA 63654220.053399

TABLE 2Zero shearrate viscosityAEGCEGTGη0at 240° C.Type[mmol/kg][mmol/kg][° C.][Pas]AP1PA 6I/6T3786125770

TABLE 3ViscosityMelt volumeTGDensitynumber VNflow rate MVRType[° C.]ρ [g/cm3][ml/g][g/10 min]HP1Polysulfone1851.2346390(360° C., 10 kg)HP2Styrene-N-1961.183phenylmale-(265° C., 10 kg)imide-maleicanhydridecopolymer

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 (semicrystalline polyamide or amorphous polyamide) 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.

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 (semicrystalline polyamide or amorphous polyamide) 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.

The melting temperature (TM) of the semicrystalline polyamides and all glass transition temperatures (TG) were each determined by means of differential scanning calorimetry.

For determination of the melting temperature (TM), as described above, a first heating run (H1) at a heating rate of 20 K/min was measured. The melting temperature (TM) then corresponded to the temperature at the maximum of the melting peak of the heating run (H1).

For determination of the glass transition temperature (TG), after the first heating run (H1), a cooling run (C) 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 (TG) was then determined as described above at half the step height of the second heating run (H2).

The zero shear rate viscosity no 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 analyzed 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.

Density was determined to DIN EN ISO 1183-1:2013.

The melt volume flow rate (MVR) was determined to DIN EN ISO 1133-1:2011.

Viscosity number was determined to ISO 307, 1157, 1628.

Blends Comprising a Single Amorphous Polymer

For production of blends, the components specified in table 4 were compounded in the ratios specified in table 4 in a DSM 15 cm3miniextruder (DSM-Micro15 microcompounder) at a speed of 80 rpm (revolutions per minute) at 260° C. for a mixing time of 3 min (minutes) and then extruded. The extrudates obtained were then ground in a mill and sieved to a particle size of <200 μm.

The blends obtained were characterized. The results can be seen in table 5.

TABLE 4(P1)(AP1)(HP1)(A1)(A2)(A3)[%[%[%[%[%[%Exampleby wt.]by wt.]by wt.]by wt.]by wt.]by wt.]C1100C27921C378.6210.4I479.6180.42

TABLE 5MagnitudeRatio ofof complexviscositySinteringviscosity atafterwindow0.5 rad/s,aging toSinteringW afterExam-240° C.beforeTMTCwindowagingple[Pas]aging[° C.][° C.]W [C][C]C13700.11219.7187.816.711.2C24830.39219.5173.224.523.9C35695.75217.7175.825.827.9I47401.18219.1187.318.115.3

The melting temperature (TM) was determined as described above.

The crystallization temperature (TC) was determined by means of differential scanning calorimetry. For this purpose, first a heating run (H) at a heating rate of 20 K/min and then a cooling run (C) at a cooling rate of 20 K/min were measured. The crystallization temperature (TC) is the temperature at the extreme of the crystallization peak.

The magnitude of the complex shear viscosity was determined by means of a plate-plate rotary rheometer at an angular frequency of 0.5 rad/s and a temperature of 240° C. A “DHR-1” rotary viscometer from TA Instruments was used, 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 are then analyzed 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 time: 20 min, preheating time after sample preparation: 1.5 min.

The sintering window (W) was determined, as described above, as the difference between the onset temperature of melting (TMonset) and the onset temperature of crystallization (TConset).

To determine the thermooxidative stability of the blends, the complex shear viscosity of freshly produced blends and of blends after oven aging at 0.5% oxygen and 195° C. for 16 hours was determined. The ratio of viscosity after storage (after aging) to the viscosity before storage (before aging) was determined. The viscosity is measured by means of rotary rheology at a measurement frequency of 0.5 rad/s at a temperature of 240° C.

It can be seen from the examples in table 5 that the use of inventive components (A), (B) and (C) in the blend achieves improved thermal stability over the pure component (A). In addition, a broadened sintering window is achieved, especially after thermal storage.

Sinter Powder for Selective Laser Sintering

For production of sinter powders, the components specified in table 6 were compounded in the ratio specified in table 6 in a twin-screw extruder (MC26) at a speed of 300 rpm (revolutions per minute) and a throughput of 10 kg/h at a temperature of 270° C. with subsequent extrudate pelletization. The pelletized material thus obtained was ground to a particle size of 20 to 100 μm.

The sinter powders obtained were characterized as described above. The results can be seen in table 7.

TABLE 6(P1)(AP1)(HP1)(HP2)(A1)(A2)[%[%[%[%[%[%Exampleby wt.]by wt.]by wt.]by wt.]by wt.]by wt.]C5100C67921C778.5210.5I858.521180.52C958.521200.5I1060.521180.5

TABLE 7Broadening ofBroadening ofMagnitude ofRatio ofsinteringsinteringcomplex viscosityviscosity afterSinteringwindow ΔWwindow ΔWat 0.5 rad/s,aging toTMTCTGSinteringwindow W aftercompared to (C8)compared to (C8)Example240° C. [Pas]before aging[° C.][° C.][° C.]window W [C]aging [C][C]after aging [C]C53700.11219.7187.85316.711.2——C66370.25217.9173.46624.123.9——C76922.92217.8170.26628.226.8——I813621.47215.01677328.831.40.64.6C915511.21215.7166.77029.431.51.24.7I1013021.08216.4168.07127.728.9−0.52.1

The sinter powders from inventive examples 18 and 110 and from comparative example C9 exhibit a distinctly broadened sintering window after aging. There is likewise a distinct improvement in the aging stability, characterized by the viscosity ratio after aging to before aging, over comparative examples C5, C6 and C7. As shown further down, the elongation at break properties of shaped bodies produced from the sinter powder according to comparative example C9, however, are much poorer than those of the shaped bodies produced from the inventive sinter powders according to examples I8 and I10.

Laser Sintering Experiments

The sinter powder was introduced with a layer thickness of 0.12 mm into the cavity at the temperature specified in table 8. The sinter powder was subsequently exposed to a laser with the laser power output specified in table 8 and the point spacing specified, with a speed of the laser over the sample during exposure of 5 m/s. The point spacing is also known as laser spacing or lane spacing. Selective laser sintering typically involves scanning in stripes. The point spacing gives the distance between the centers of the stripes, i.e. between the two centers of the laser beam for two stripes.

TABLE 8TemperatureLaser powerLaser speedPoint spacingExample[° C.]output [W][m/s][mm]C52091850.2C61952050.2C72002550.2I81952550.2C91952550.2I101982550.2

Subsequently, the properties of the tensile bars (sinter bars) obtained were determined. The tensile bars (sinter bars) obtained were tested in the dry state after drying at 80° C. for 336 h under reduced pressure. The results are shown in table 9. In addition, Charpy bars were produced, which were likewise tested in dry form (according to ISO179-2/1 eU: 1997+Amd.1:2011).

The warpage of the sinter bars obtained was determined by placing the sinter bar with the concave side down onto a planar surface. The distance (am) between the planar surface and the upper edge of the middle of the sinter bar was then determined. In addition, the thickness (dm) in the middle of the sinter bar was determined. Warpage in % is then determined by the following formula:
V=100·(am−dm)/dm

The dimensions of the sinter bars were typically length 80 mm, width 10 mm and thickness 4 mm.

The flexural strength corresponds to the maximum stress in the bending test. The bending test is a three-point bending test according to EN ISO 178:2010+A1:2013.

Processability was assessed quantitatively with “2” meaning “good”, i.e. low warpage of the component, and “5” meaning “inadequate”, i.e. severe warpage of the component.

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

The water absorption of the tensile bars (sinter bars) obtained was determined by weighing the tensile bars in the dried state (after storage at 80° C. under reduced pressure for 336 hours) and in the conditioned state (after storage at 70° C. and 62% relative humidity for 336 hours).

TABLE 9CharpyCharpyWarpageTensileimpactnotchof flexuralFlexuralTensilemodulusElongationresistanceimpactWaterbar fromProcessibilitystrengthstrengthof elasticityat breakaCUstrengthabsorptionExampleSLS [%]in SLS[MPa][MPa][MPa][%][kJ/m2][kJ/m2][% by wt.]C545-554C6not2determinedC752 ± 1421006436001.95.01.52.7I832 ± 71957633002.87.61.651.9C930 ± 314328.531000.9—I100.4 ± 1.21—68.935002.58.1

It is apparent that a shaped body produced with the sinter powder according to comparative example C9 does have low warpage, but also exhibits only very low elongation at break.

The shaped bodies produced from the inventive sinter powders according to examples I8 and I10 have reduced warpage together with elevated elongation at break and impact resistance.

It is apparent that shaped bodies produced with the sinter powder (SP) of the invention give a lower water absorption of only 1.9% by weight. The theoretical expectation was 2.16% by weight, the theoretical calculation being based on the assumption that, when the sinter powder (SP) comprises 20% by weight of polyamides of various components that do not absorb water, the sinter powder exhibits 80% of the water absorption of a sinter powder comprising exclusively polyamide (C7).