Pretreated Material for Laser Sintering

Abstract

Disclosed is a composition, in particular to a building material for an additive manufacturing process, wherein the composition is treated by heat. Further, the present invention is directed to a process for the manufacturing of the inventive composition and to a device comprising the inventive composition and the use of the inventive composition.

Claims

1. A composition comprising at least one polymer in the form of a powder; wherein the polymer comprises at least one thermoplastic polymer selected from the group consisting of a polyetherimide, a polycarbonate, a polysulfone, a polyphenylene sulfone, a polyphenylene oxide, a polyether sulfone, an acrylnitrile-butadiene-styrol-copolymer (ABS), an acrylnitrile-styrol-acrylate-copolymer (ASA), a polyvinyl chloride, a polyacrylate, a polyester, a polyamide, a polypropylene, a polyethylene, a polyarylether ketone, a polyether, a polyurethane, a polyimide, polyamide imide, a polyolefine, a polyarylene sulfide and copolymers thereof; wherein the polymer is treated by heat at a temperature of at least about 0.1° C. below the melting point and not more than about 2° C. below the melting point; and wherein the heat treatment is carried out for at least about 1 hour and/or not more than about 24 hours.

2. A composition according to claim 1, wherein the polymer comprises at least one semicrystalline polymer; and/or at least one amorphous polymer.

3. A composition according to claim 1, wherein the polymer blend comprises a polypropylene and/or a copolymer and/or a polymer blend thereof.

4. A composition according to claim 1, wherein the polypropylene has a melting temperature Tm of at least about 100° C., and/or wherein the polypropylene has a glass transition temperature Tg of at least about −25° C.

5. A composition according to claim 2, having a process window of at least about 10° C.

6. A composition according to claim 1, wherein the polymer particles of the composition have a particle size distribution as follows: d10=at least 30 μm and/or not more than 50 μm; d50=at least 70 μm and/or not more than 90 μm; d90=at least 90 μm and/or not more than 120 μm.

7. A composition according to claim 1, wherein the composition has a distribution width (d90−d10)/d50 of at least 0.50.

8. A composition according to claim 1, wherein the polymer particles have a sphericity of at least about 0.8.

9. A composition according to claim 1, wherein the composition comprises at least one flow agent.

10. A process for the manufacture of a composition according to claim 1, wherein the process comprises the following steps: (i) providing at least one thermoplastic polymer, wherein the polymer comprises at least one thermoplastic polymer selected from the group consisting of a polyetherimide, a polycarbonate, a polysulfone, a polyphenylene sulfone, a polyphenylene oxide, a polyether sulfone, an acrylnitrile-butadiene-styrol-copolymer (ABS), an acrylnitrile-styrol-acrylate-copolymer (ASA), a polyvinyl chloride, a polyacrylate, a polyester, a polyamide, a polypropylene, a polyethylene, a polyarylether ketone, a polyether, a polyurethane, a polyimide, polyamide imide, a polyolefine, a polyarylene sulfide and copolymers thereof; and treating the polymer by heat at a temperature of at least about 0.1° C. below the melting point and not more than about 2° C. below the melting point for at least about 1 hour and/or not more than about 24 hours.

11. A process for the manufacture of a composition according to claim 10, wherein the process comprises the following steps: (a) the at least one thermoplastic polymer is treated by heat to increase a difference between the melting temperature and/or the onset melting temperature and the recrystallisation temperature and/or onset recrystallisation temperature; and/or (b) the least one thermoplastic polymer has been treated by heat to increase a temperature at which onset of melting occurs for the at least one thermoplastic polymer.

12. A process for the manufacture of a 3D object, comprising the steps: (i) applying a layer of a composition according to claim 1 onto a production panel; (ii) selectively solidifying the applied layer of the composition at sites representing a cross section of the object to be manufactured; and (iii) lowering the carrier and repeating the steps for applying and solidifying until the 3D object is finished.

13. A composition obtained by a process according to claim 10 or 11.

14. A 3D object comprising a composition according to claim 1.

15. A method of manufacturing a 3D object comprising: applying a composition according to claim 1 in a manufacturing process selected from the group consisting of laser sintering, high speed sintering, binder jetting, multi jet fusion, selective mask sintering, selective laser melting, and laser pro fusion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0127] Further characteristics of the present invention are derived from the examples in combination with the claims and the figures. Single features may be, in a particular embodiment, realised in combination with other features and do not limit the scope of protection of the present invention. The following description of the examples according to the invention may relate to the figures, whereby

[0128] FIG. 1 shows the DSC curves for the untreated and treated Polymer 05 pellets (heat treatment 142° C. for 6 hrs). There is a clear increase in both the Tmo and Tm of the material as well as a reduction in the difference between the Tmo and Tm.

[0129] FIG. 2 shows the DSC curves for the untreated and treated Polymer 09 pellets (heat treatment 147° C. for 8 hrs). Increases to the Tmo and Tm as well as a reduction in the difference between the Tmo and Tm are displayed.

[0130] FIG. 3 shows the DSC curves for the untreated and treated Polymer 18 pellets (heat treatment 147° C. for 8 hrs). Increases to the Tmo and Tm as well as a reduction in the difference between the Tmo and Tm are displayed.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Examples

Materials:

[0131] a) Polymer 05 (Braskem, Polypropylene pellets)

[0132] b) Polymer 09 (Braskem, Polypropylene pellets)

[0133] c) Polymer 18 (Braskem, Polypropylene pellets)

Heat Treatment:

[0134] The polymer samples listed above were heated in a heating device (Grieve, Truck Oven TCH-550). The optimal heating parameters for each polymer sample were as follows:

[0135] (1) Polymer 05 was heated to a temperature of 142° C. for 6 hours,

[0136] (2) Polymer 09 was heated to a temperature of 147° C. for 8 hours, and

[0137] (3) Polymer 18 was heated to a temperature of 147° C. for 8 hours.

Temperature Measurements by DSC:

[0138] The temperature measurements for all samples listed above were produced according to ASTM D3418-03 (Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallisation of Polymers by Differential Scanning calorimetry) with a TA Instruments TA Q20 DSC tool.

[0139] For the evaluation of the Tm, the Trc and the onset points Tmo and Tro, standard aluminum pans were used and the heating and cooling was performed for all samples as follows: (1) equilibrating at 40° C., (2) ramping at 10° C./min to 175° C., (3) holding isothermal for 1 minute, (4) ramping at −10° C./min to 40° C., (5) holding isothermal for 1 minute. [0140] The melting point of polypropylene in general can range between 120−170° C.

TABLE-US-00001 TABLE 1 Melt and recrystallisation data for various heat treated Polymer 05 samples. Melting Melting Recrys- Recrys- Peak Onset tallisation tallisation Sample (“Tm”) (“Tmo”) Peak (“Trc”) Onset (“Tro”) Polymer 05 143.86° C. 124.12° C. 106.08° C. 109.86° C. Control Sample, Untreated Polymer 05, 149.87° C. 141.72° C. 106.06° C. 109.83° C. heat treated 6 hours at 142° C. Polymer 05, 143.44° C. 130.33° C. 107.22° C. 111.33° C. heat treated 16 hours at 128° C. Polymer 05, 144.83° C. 132.01° C. 107.30° C. 111.53° C. heat treated 16 hours at 131° C. Polymer 05, 145.23° C. 136.35° C. 107.57° C. 111.54° C. heat treated 14 hours at 135° C.

TABLE-US-00002 TABLE 2 Melt and recrystallisation data for various heat treated Polymer 09 samples. Melting Melting Recrys- Recrys- Peak Onset tallisation tallisation Sample (“Tm”) (“Tmo”) Peak (“Trc”) Onset (“Tro”) Polymer 09 147.67° C. 134.00° C. 104.89° C. 108.18° C. Control Sample, Untreated Polymer 09, 154.29° C. 146.97° C. 103.32° C. 107.35° C. heat treated 8 hours at 147° C.

TABLE-US-00003 TABLE 3 Melt and recrystallisation data for various heat treated Polymer 18 samples. Melting Melting Recrys- Recrys- Peak Onset tallisation tallisation Sample (“Tm”) (“Tmo”) Peak (“Trc”) Onset (“Tro”) Polymer 18 147.94° C. 135.45° C. 119.07° C. 122.64° C. Control Sample, Untreated Polymer 18, 153.49° C. 146.77° C. 118.57° C. 122.23° C. heat treated 8 hours at 147° C.

Grinding

[0141] The polymer samples are then optionally ground to a powder with particle size d50 of 80 μm in a cryogenic grinding process (Vortec, Impact Mill M-1).

Laser Sintering

[0142] Now that the polymer samples are in powder form they can be used in the SLS machines (Integra, Sinterstation 2500 Plus) and (EOS, P396).

[0143] The invention illustratively described herein suitably may be practised in the absence of any element or elements, limitation or limitations which is/are not specifically disclosed herein. Thus, for example, in each instance herein any of the terms “comprising”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.

[0144] All references cited in this specification are herewith incorporated by reference with respect to their entire disclosure content and the disclosure content specifically mentioned in this specification.