Process for producing a three-dimensional object

Abstract

A process for producing a three-dimensional object by selectively layer-by-layer solidification of a powdery material layer at the locations corresponding to the cross-section of the object in a respective layer by exposure to electromagnetic radiation. The powdery material comprises at least one polymer which is obtainable from its melt only in substantially amorphous or completely amorphous form, or a polyblend which is obtainable from its melt only in substantially amorphous or completely amorphous form. The powdery material has a specific melting enthalpy of at least 1 J/g.

Claims

1. A process for producing a three-dimensional object, the process comprising: selectively solidifying, layer-by-layer, a powdery material at locations corresponding to a cross-section of the object in a respective layer by exposure to electromagnetic radiation, wherein the powdery material comprises at least one polymer which is obtainable from its melt only in substantially amorphous or completely amorphous form, or a polyblend which is obtainable from its melt only in substantially amorphous or completely amorphous form; wherein the powdery material has a specific melting enthalpy of at least 1 J/g; wherein the powdery material has a powder distribution with (i) a d90 value of <150 μm and (ii) a mean particle size (d50 value) of at least 20 μm; and wherein the powdery material has a bulk density of at least 0.35 g/cm.sup.3.

2. The process according to claim 1, wherein the powdery material comprises at least one of polymers selected from the group consisting of polyetherimides, polycarbonates, polyphenylene sulfones, polyphenylene oxides, polyethersulfones, acrylonitrile-butadiene-styrene copolymers (ABS), acrylonitrile-styrene-acrylate copolymers (ASA), polyvinyl chloride, polyacrylates, polyesters, polyamides, polyaryletherketones, polyethers, polyurethanes, polyimides, polyamidimides, polysiloxanes, polyolefins and copolymers which comprise at least two different repeating units of the abovementioned polymers, and/or at least one polyblend based on the abovementioned polymers and/or copolymers.

3. The process according to claim 1, wherein the powdery material is preheated before being solidified by exposure to electromagnetic radiation; and wherein the processing temperature is (i) at least 10° C. above a glass transition temperature of the at least one polymer or copolymer or polyblend; and/or (ii) at most at the maximum processing temperature at which the powdery material refrains from sticking together.

4. The process according to claim 1, wherein the powdery material has additionally one or more of the following features: (iii) the mean particle size (d50 value) is at most 100 μm; (iv) the powdery polymer material has a sphericity greater than 0.8; (v) the powdery polymer material has a distribution width ((d90−d10)/d50) of less than 3; (vi) the powdery polymer material has a bulk density of at most 0.70 g/cm.sup.3, (vii) the powdery polymer material has a melt viscosity, determined by ISO-1133 at 5 kg load and a test temperature in a temperature range of 50-80° C. above the highest melting temperature, of at least 10 cm.sup.3/10 min and/or at most 150 cm.sup.3/10 min.

5. The process according to claim 1, wherein the powdery material has a polyetherimide content of at least 1% by weight and/or of at most 90% by weight, wherein the polyetherimide content respectively refers to a total content of polymers in the powdery material without taking additives and fillers into account, and wherein, in a case of the use of a polyetherimide-containing polyblend, a polyetherimide proportion by weight of a polyetherimide-containing polyblend is included in the polyetherimide content.

6. The process according to claim 1, wherein the powdery material comprises a polyetherimide selected from the group consisting of: a polyetherimide having repeating units A according to a formula ##STR00033## and repeating units B according to a formula ##STR00034## where a proportion of repeating units A and a proportion of repeating units B, respectively based on a total content of A and B, respectively is at least 1% and/or at most 99%, wherein R.sub.1 and R.sub.3 are moieties which are different from each other and which are independently selected from the group consisting of ##STR00035## and wherein R.sub.2 and R.sub.4 are moieties which are different from each other and which are independent of each other and independent of R.sub.1 and R.sub.3 selected from the group consisting of ##STR00036## a polyetherimide having repeating units according to a formula ##STR00037## wherein R.sub.5 is a moiety selected from the group consisting of ##STR00038## and wherein R.sub.6 is a moiety independent of R.sub.5 selected from the group consisting of ##STR00039## a polyetherimide having repeating units C according to a formula ##STR00040## and repeating units D according to a formula ##STR00041## wherein a proportion of the repeating units C and a proportion of the repeating units D, respectively based on a total content of C and D, respectively is at least 1% and/or at most 99%, wherein R.sub.7 is a moiety selected from the group consisting of ##STR00042## and wherein R.sub.8 is a moiety independent of R.sub.7 selected from the group consisting of ##STR00043##

7. The process according to claim 1, wherein the powdery material comprises a polyetherimide having repeating units according to a formula ##STR00044## wherein R.sub.5 is a moiety selected from the group consisting of ##STR00045## and wherein R.sub.6 is a moiety independent of R.sub.5 selected from the group consisting of ##STR00046## wherein the powdery material comprises polyetherimide having repeating units according to a formula ##STR00047## or repeating units according to a formula ##STR00048## or repeating units according to a formula ##STR00049##

8. The process according to claim 1, wherein the powdery material comprises a polyetherimide-polysiloxane copolymer having repeating units E according to a formula ##STR00050## and repeating units F according to a formula ##STR00051## wherein a proportion of the repeating units E and the proportion of the repeating units F, respectively based on the total content of E and F, respectively is at least 1% and/or at most 99%.

9. The process according to claim 1, wherein the powdery material comprises polycarbonate having repeating units G according to a formula ##STR00052## and repeating units H according to a formula ##STR00053## wherein R.sub.9 and R.sub.10 are moieties which are different from each other and which are independently selected from the group consisting of ##STR00054## wherein a proportion of the repeating units G and a proportion of the repeating units H, respectively based on the total content of G and H, respectively is at least 1% and/or at most 99%.

10. The process according to claim 1, wherein the powdery material comprises polycarbonate having repeating units according to a formula ##STR00055## wherein R.sub.11 is a moiety selected from the group consisting of ##STR00056##

11. The process according to claim 1, wherein the powdery material comprises a copolymer having repeating units according to a formula ##STR00057##

12. The process according to claim 1, wherein the specific melting enthalpy of the powdery material is at least 2 J/g.

13. The process according to claim 1, wherein the powdery material additionally comprises an additive, selected from the group consisting of polysiloxanes, heat stabilizers, oxidation stabilizers, UV stabilizers, fillers, reinforcing fibers, flame retardants, coloring agents, IR absorbers, and flow additives, and mixtures thereof.

14. The process according to claim 1, wherein the three-dimensional object is produced so as to have at least substantially amorphous or completely amorphous regions; and/or wherein the three-dimensional object is at least partially composed of a composite material and is produced so that the matrix of the composite material has at least substantially amorphous or completely amorphous regions.

15. The process according to claim 1, wherein the three-dimensional object is produced to have an xy-shrinkage factor during its solidification of at most 2%.

16. The process according to claim 1, wherein the powdery material previously had been produced by a process selected from any of the following Processes I to III: Process I comprising the steps: dissolving in a first organic solvent a polymer material comprising at least one polymer which is obtainable from its melt only in substantially amorphous or completely amorphous form so as to create a solution; emulsifying the solution with a liquid having a lower vapor pressure than the first organic solvent, in the presence of an emulsion stabilizer; precipitating particulate polymer by evaporation of at least part of the first organic solvent, or by extraction of the first organic solvent by a second organic solvent which is miscible with the first organic solvent and the liquid for emulsification, and evaporation of at least part of the first organic solvent; and obtaining the powdery material; Process II comprising the steps: dissolving in an organic solvent a polymer material comprising at least one polymer which is obtainable from its melt only in substantially amorphous or completely amorphous form so as to create a solution; precipitating particulate polymer by adding the solution to a liquid which does not itself crystallize and in which the organic solvent, in which the polymer material was dissolved, is partially or completely soluble and in which the at least one polymer is less soluble than in the organic solvent in which the polymer material was dissolved, and obtaining the powdery material; Process III comprising the steps: bringing a polymer material comprising at least one polymer, which is obtainable from its melt only in substantially amorphous or completely amorphous form, into contact with a solvent which, at a first lower temperature does not dissolve the polymer at the first temperature, but which dissolves the polymer at a second temperature which is higher than the first lower temperature, so as to obtain a polymer-solvent mixture; heating the polymer-solvent mixture while stirring to the second temperature or higher to dissolve the polymer in the solvent; cooling to or below the first temperature with stirring, wherein the polymer precipitates and crystallizes; and obtaining the powdery material.

17. The process according to claim 1, wherein the powdery material previously had been produced by a process selected from Process A) or B): Process A) comprising the steps: crystallizing a particulate polymer material comprising at least one polymer, which is obtainable from its melt only in substantially amorphous form, by contacting the particulate polymer material in an organic non-solvent or partial solvent to swell the polymer, wherein the contacting is carried out with stirring for a sufficient time that the polymer material is crystallized, separation of the non-solvent or partial solvent, and subsequently drying, grinding for reducing the primary particle size of the crystallized powdery polymer material, post-crystallization after grinding by tempering or by treatment with non-solvent or partial solvent and subsequent separation of the non-solvent or partial solvent, and obtaining the powdery material; Process B) comprising the steps: producing crystalline or semi-crystalline particulate polymer by polymerizing monomers which are capable of making the polymer in a solvent, the solvent being for the monomers but is a non-solvent for the polymer and in which the polymer crystallizes to obtain a crystalline or semi-crystalline powder, post-crystallization by tempering or by treatment with a non-solvent or a partial solvent, and obtaining the powdery material.

18. The process according to claim 17, wherein in Process A), prior to the crystallization step, the particulate polymer material for forming amorphous polymer is carried out by melt based powder generation processes selected from melt dispersion, microgranulation and fiber spinning plus cutting; or wherein in Process B) the degree of crystallization and/or a grain size distribution is obtained directly in the step of polymerization and crystallization, wherein the particle size distribution and/or the degree of crystallization in the polymerization is controlled by type of non-solvent, by a temperature profile, by a stirring rate, by a polymerization reaction rate and/or by a choice of monomers; or wherein in Process B) a semi-crystalline coarse powder is obtained which is subsequently further comminuted by grinding into a desired grain size distribution.

19. The process according to claim 17, wherein the powdery material has been obtained in a final particle form and final particle size/size distribution without subjecting particulate polymer intermediate product or the powdery material to a primary particle size-reducing treatment.

20. The process according to claim 1, wherein the powdery material previously had been produced by a process comprising the steps: providing a polymer which is obtainable from its melt only in substantially amorphous or completely amorphous form, spinning fibers from a melt or a solution of the polymer so as to obtain polymer fibers, stretching the polymer fibers to produce semi-crystalline proportions, comminution of the polymer fibers to powdery material.

21. The process according to claim 17, wherein the powdery material has been subjected to a tempering treatment below the highest melting point and above the highest glass transition temperature, after the powdery material is produced and before the powdery material is subjected to the production of the three-dimensional object; and/or the powdery material has been subjected to a tempering treatment which leads to a formation of only one melting point in the presence of a plurality of melting points.

22. The process according to claim 1, wherein the polymer or the polyblend of the powdery material subjected to the process for producing the three-dimensional object previously had been obtained by spinning of the polymer or the polyblend from melt or from solution to make fibers of the polymer or the polyblend, stretching the fibers of the polymer or the polyblend for making semi-crystalline proportions, and diminution of the fibers into the powdery material.

23. The process according to claim 1, wherein the powdery material comprises a polyetherimide or a polyblend of polyetherimide and at least one other polymer.

24. A powdery material for additive manufacturing, comprising at least one melt-amorphous polymer or melt-amorphous polyblend by being obtainable from its melt only in substantially amorphous or completely amorphous form, wherein the powdery material has a specific melting enthalpy of at least 1 J/g; wherein the powdery material has a powder distribution with (i) a d90 value of <150 μm and (ii) a mean particle size (d50 value) of at least 20 μm; and wherein the powdery polymer material has a bulk density of at least 0.35 g/cm.sup.3 and/or at most 0.70 g/cm.sup.3, wherein the powdery material comprises at least one of the polymers selected from the group consisting of polyetherimides, polycarbonates, polyphenylene sulfones, polyphenylene oxides, polyethersulfones, acrylonitrile-butadiene-styrene copolymers (ABS), acrylonitrile-styrene-acrylate copolymers (ASA), polyvinyl chloride, polyacrylates, polyesters, polyamides, polyaryletherketones, polyethers, polyurethanes, polyimides, polyamidimides, polysiloxanes, polyolefins and copolymers which comprise at least two different repeating units of the abovementioned polymers, and/or at least one polyblend based on the abovementioned polymers and copolymers.

25. The powdery material according to claim 24 comprising a polymer selected from the group consisting of a polymer, copolymer or polyblend of a polyetherimide having repeating units according to a formula ##STR00058## wherein R.sub.5 is a moiety selected from the group consisting of ##STR00059## and wherein R.sub.6 is a moiety independently of R.sub.5 selected from the group consisting of ##STR00060## a polymer, copolymer or polyblend comprises repeating units according to a formula ##STR00061## a polymer, copolymer or polyblend of a polyetherimide having a property selected from: having a melting point of at least 260° C. and a specific melting enthalpy of at least 4 J/g, having a bulk density of at least 0.40 g/cm′ and/or at most 0.70 g/cm.sup.3, having a grain size distribution defined as d90<150 μm and d50 of at least 30 μm and/or at most 70 μm, having a sphericity of at least 0.8, having a melt viscosity determined by ISO-1133 at 5 kg load and 360° C. test temperature of at least 10 cm.sup.3/10 min and/or at most 150 cm.sup.3/10 min.

26. A three-dimensional object obtained by selective layer-by-layer solidification of a powdery material as defined in claim 24.

27. The powdery material according to claim 24 having one or more of the following characteristics: a mean particle size (d50 value) of at least 20 μm and/or of at most 100 μm; a sphericity of at least 0.8; a distribution width ((d90−d10)/d50) of less than 3.

28. The powdery material according to claim 24, having been obtained by spinning of the melt-amorphous polymer or the melt-amorphous polyblend from melt or from solution to make fibers of the polymer or the polyblend, stretching the fibers of the polymer or the polyblend for making semi-crystalline proportions, and diminution of the fibers into the powdery material, wherein the resulting powdery material has an aspect ratio of about 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the invention result from the description of the examples with reference to the attached figures.

(2) FIG. 1 shows a schematic and vertical view of a device that can be used to carry out the inventive process for producing a three-dimensional object.

(3) FIG. 2 Block diagram of the process for producing the powdery material according to a first variant of an embodiment of the invention.

(4) FIG. 3 Block diagram of the process for producing the powdery material according to a second variant of this embodiment.

(5) FIG. 4 Block diagram of the process for producing the powdery material according to a further embodiment of the invention.

(6) FIG. 5 Block diagram of the process for producing the powdery material according to another further embodiment of the invention.

(7) FIG. 6 shows a microscopic image of a powdery material according to an example of the present invention.

(8) FIG. 7 shows DSC curves for an example according to the invention, and

(9) FIG. 8 shows another DSC curve for the same example.

(10) FIG. 9 shows DSC curves for another example according to the invention, and

(11) FIG. 10 shows another DSC curve for the same example.

(12) FIG. 11 shows DSC curves for another example according to the invention, and

(13) FIG. 12 shows another DSC curve for the same example.

(14) FIG. 13 shows DSC curves for another example according to the invention, and

(15) FIG. 14 shows another DSC curve for the same example.

(16) FIG. 15 shows DSC curves for another example according to the invention.

(17) FIG. 16 shows DSC curves for yet another example according to the invention, and

(18) FIG. 17 shows a microscopic image of a powdery material according to the same example.

(19) FIG. 18 shows a microscopic image of a powdery material according to another example of the present invention.

(20) FIG. 19 shows DSC curves for another example according to the invention.

(21) FIG. 20 shows DSC curves for a comparative example which was not prepared according to the invention.

(22) FIG. 21 shows DSC curves for another comparative example which was not prepared according to the invention.

(23) FIG. 22 shows a microscopic image of a powdery material according to a comparative example (sample P4 from test series V26).

(24) FIG. 23 shows a thin-film image of sample P4 from test series V26.

(25) FIG. 24 shows a thin film image of sample P3—according to the invention—from test series V26.

(26) FIG. 25 shows DSC curves with polymer powders of the example series V26.

(27) FIG. 26 shows DSC curves of built parts obtained with polymer powders from example series V26.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(28) The device shown in FIG. 1 is a laser sintering or laser melting device 1 for producing an object 2 from a powdery material 15. In this context, powdery material 15 is also referred to as “build-up material”. For the choice of powdery material, reference is made to the description above.

(29) The device 1 contains a process chamber 3 with a chamber wall 4. In the process chamber 3 an open top container 5 with a container wall 6 is arranged. A working plane 7 is defined by the upper opening of the vessel 5, whereby the area of working plane 7 within the opening which can be used to construct object 2 is referred to as construction area 8. A support 10 movable in a vertical direction V is arranged in the container 5, to which a base plate 11 is attached, which closes off the container 5 downwards and thus forms its bottom. The base plate 11 can be a plate formed separately from the support 10 and attached to the support 10, or it can be formed integrally with the support 10. Depending on the powder used and the process, a building platform 12 can be placed on the base plate 11 as a building base on which object 2 is built. Object 2 can also be mounted on the base plate 11 itself, which then serves as the building base. In FIG. 1, the object to be constructed is shown in an intermediate state. It consists of several solidified layers and is surrounded by unsolidified powdery material 13.

(30) The device 1 further contains a storage container 14 for a powdery material 15 solidifiable by electromagnetic radiation and a coater 16 movable in a horizontal direction H for applying layers of the powdery material 15 within the construction area 8. Preferably a radiation heating 17 is arranged in the process chamber 3, which serves for heating the applied powdery material 15. An infrared radiator, for example, can be provided as radiation heater 17.

(31) The apparatus 1 further comprises an radiation device 20 with a laser 21 which generates a laser beam 22 which is deflected by a deflection device 23 and focused by a focusing device 24 onto the working plane 7 via a coupling window 25 mounted on the upper side of the process chamber 3 in the chamber wall 4 via a coupling window 25.

(32) The apparatus 1 further comprises control means 29 by means of which the individual components of the apparatus 1 are controlled in a coordinated manner to perform a process of producing a three-dimensional object 2. The controller 29 may include a CPU whose operation is controlled by a computer program (software). The computer program may be stored separately from device 1 on a storage medium from which it can be loaded into device 1, in particular into control device 29.

(33) Depending on the processing temperature, the laser sintering devices distributed by the applicant under the type designations P110, P396, P770 and P800, for example, have proved to be suitable for carrying out the invention.

(34) During operation, to apply a layer of powdery material 15, the carrier 10 is lowered by a height which preferably corresponds to the desired thickness of the layer of powdery material 15. The coater 16 first moves to the storage container 14 and takes from it a sufficient quantity of powdery material 15 to apply a layer. Then the coater 16 moves over the construction area 8 and applies a thin layer of the powdery material 15 onto the construction base 10, 11, 12 or an already existing powder layer. The application takes place at least over the entire cross-section of the object to be produced, preferably over the entire construction area 8. The powdery material 15 is preferably heated to a processing temperature by means of radiant heating 17. The cross-section of the object 2 to be produced is then scanned by the laser beam 22 so that this area of the applied layer is solidified. The steps are repeated until object 2 is finished and can be removed from container 5.

(35) The invention is preferably applied to laser sintering or laser melting, but is not limited to it. It can be applied to various processes as far as these involve the production of a three-dimensional object by layer-by-layer application and selective solidification of a powdery material by exposure to electromagnetic radiation.

(36) The radiation facility 20 may, for example, include one or more gas or solid-state lasers or lasers of any other type, such as laser diodes, in particular VCSEL (Vertical Cavity Surface Emitting Laser) or VECSEL (Vertical External Cavity Surface Emitting Laser) line exposure devices. In general, any radiation source can be used as a radiation device with which electromagnetic radiation can be selectively applied to a layer of powdery material. For example, instead of a laser, another light source or any other source of electromagnetic radiation capable of solidifying the powdery material 15 can be used. Instead of deflecting a beam, exposure with a mobile line exposer can also be used. Also on selective mask sintering, where a two-dimensional light source and a mask are used, or on high-speed sintering (HSS), where a material is selectively applied to the powdery material, which increases the radiation absorption at the locations corresponding to the cross-section of the three-dimensional object 2 (absorption sintering) or reduces it at the remaining locations of the construction area 8 (inhibition sintering), and is then exposed non-selectively over a large area or with a movable line exposer, the invention can be applied.

(37) According to the invention, it is preferable to preheat the powdery material 15 before it is solidified by exposure to electromagnetic radiation. During preheating, the powdery material 15 is heated to an elevated processing temperature so that less energy is required from the electromagnetic radiation used for selective solidification. Preheating can, for example, be carried out by means of radiant heating. The maximum processing temperature is defined as the processing temperature of the powdery material 15 at which the powdery material 15 just does not fuse, so that no aggregates of powder particles form, and the powdery material is still sufficiently flowable for the coating process. The maximum processing temperature depends in particular on the type of powdery material used. The processing temperature is preferably selected so that it is at least 10° C. (more preferably at least 15° C. and even more preferably at least 20° C.) above the glass transition temperature of the at least one polymer or copolymer or polyblend and/or at most at the maximum processing temperature (more preferably at most 20° C., even more preferably at most 15° C. and even more preferably at most 10° C. below the melting point of the at least one polymer or copolymer or polyblend). The processing temperature shall preferably be above the glass transition temperature and below the melting point of the at least one polymer. This ensures that the processing temperature is as high as possible without the powder material sticking together. If a polyblend is used, it is preferred that the processing temperature is at least 10° C. (more preferably at least 15° C. and even more preferably at least 20° C.) above the highest glass transition temperature of the polyblend and/or at most the maximum processing temperature (more preferably at most 50° C., even more preferably at most 20° C. and even more preferably at most 10° C. below the highest melting point of the polyblend) in order to achieve as high a processing temperature as possible without sticking of the powdery material. The processing temperature is preferably above the highest glass transition temperature and below the highest melting point of the polyblend.

(38) If the powdery material comprises a polyblend based on at least one polyetherimide and one polycarbonate, the invention states that it is preferable to preheat the powdery material before it is solidified by the action of electromagnetic radiation and to select the processing temperature accordingly, in that it is at least 10° C. (more preferably at least 15° C. and even more preferably at least 20° C.) above the glass transition temperature of the polyetherimide and at most 20° C. (more preferably at most 15° C. and even more preferably at most 10° C.) below the melting point of the polycarbonate in order to achieve as high a processing temperature as possible without the powdery material sticking together in the process.

(39) Process for Producing the Powdery Material

(40) The process described above for producing the powdery material according to a first and a second variant of a first embodiment is illustrated schematically in the block diagrams shown in FIG. 2 and FIG. 3, respectively. The process described above for producing the powdery material according to a second embodiment is illustrated schematically in the block diagram shown in FIG. 4. The process described above for producing the powdery material according to a third embodiment is schematically illustrated in the block diagram shown in FIG. 5.

(41) Methods Applied

(42) For the examples described below, among others, results obtained by means of dynamic differential calorimetry (hereinafter referred to as “DSC”, derived from the English term “Differential Scanning calorimetry”) are given. In addition, optical methods are used to provide certain measurement results for the size and shape of particles of powdery material. For example, the degree of crystallinity was determined using the method described in the book by Rudolf Allmann and Amt Kern “Röntgenpulverdiffraktometrie—Rechnergestütze Auswertung, Phaseanalyse and Strukturbestimmung” (Springer-Verlag Berlin Heidelberg 2003).

(43) 1. DSC:

(44) The measurements were performed on a DSC instrument of the type “Mettler Toledo DSC823e” with automatic sample changer. The evaluations were performed with the software “STARe Software”, version 9.30 (or version 15.00 from V26). Nitrogen 5.0, i.e. nitrogen with a purity of 99.999 volume percent, was used as purge gas. The measurements were carried out in accordance with DIN EN ISO 11357.

(45) For the DSC measurements, the methods DSC1 to DSC4 and DSC6 were used, which differ from each other with regard to the temperature program. The methods used for the DSC measurements are described below. A DSC measurement is divided into successive sections (“segments”). The sample is either kept at a constant temperature during a segment, in which case the operating mode is referred to as “isothermal”, or heated or cooled, in which case the operating mode is referred to as “dynamic”. In the tables below, for each segment with an “isothermal” mode, the duration of the segment, referred to as the “hold time”, is given. The holding time is the time for which the sample is held at the specified temperature (start temperature or, identical to this, end temperature). In the following tables, for each segment with the “dynamic” mode of operation, the rate at which the temperature of the sample is changed until it reaches the end temperature at the end of the segment, starting from the start temperature at the beginning of the segment. If the temperature increases during the segment, the rate has a positive sign and is referred to as the “heating rate”. If the temperature decreases during a segment, the rate has a negative sign and is referred to as the “cooling rate”.

(46) From DSC measurements, the glass transition temperature T.sub.g, the melting point T.sub.m and the specific melting enthalpy ΔH.sub.m were determined for various samples in accordance with the DIN EN ISO 11357 standard. In the DSC curves shown in the figures, the glass transition temperature T.sub.g is designated as “Midpoint”. In the DSC curves shown in the figures, the melting point T.sub.m is marked with “Peak”. The integral of the melting peak of a DSC curve is referred to as “integral” in the DSC curves shown in the figures. The specific melting enthalpy ΔH.sub.m is referred to as “normalized” in the DSC curves shown in the figures.

(47) The conditions of the DSC1 method are described in Table 1. This serves to determine the melting point, melting enthalpy and crystallization point according to the heating and cooling rate recommended in the standard DIN EN ISO 11357. The glass transition temperature is also determined with this method in the same heating run, but deviating from the standard DIN EN ISO 11357 with a rate of 20° C./min.

(48) TABLE-US-00001 TABLE 1 Start- Final- Heating/cooling rate Operating Temperature Temperature [° C./min] or holding Segment mode [° C.] [° C.] time [min] ]1[ isothermal 0 0 3 min ]2[ dynamic 0 400  20° C./min ]3[ isothermal 400 400 3 min ]4[ dynamic 400 0 −20° C./min ]5[ isothermal 0 0 3 min ]6[ dynamic 0 400  20° C./min

(49) The DSC2 method is used to simulate a laser sintering process with a processing temperature of 250° C. The process is performed by means of the DSC2 method. In the segment ]2[ the sample is heated up to the processing temperature. In the segments ]3[ and ]4[ the effect of a laser beam on the sample is simulated by very rapid heating to a temperature above the processing temperature immediately followed by very rapid cooling, as is the case with laser sintering. In the segment ]5[, whose final temperature is below the glass transition temperature of the sample, slow cooling takes place in order to simulate the cooling process in the course of laser sintering. In the segment ]8[ the sample is analyzed in the course of a new heating. The conditions of the DSC2 method are described in Table 2.

(50) TABLE-US-00002 TABLE 2 Start- Final- Heating/cooling Operating Temperature Temperature rate [° C./min] or Segment mode [° C.] [° C.] holding time [min] ]1[ isothermal 0 0 3 min ]2[ dynamic 0 250  20° C./min ]3[ dynamic 250 350  50° C./min ]4[ dynamic 350 250 −50° C./mm ]5[ dynamic 250 200 −0.1° C./min  ]6[ dynamic 200 0 −20° C./min ]7[ isothermal 0 0 3 min ]8[ dynamic 0 350  20° C./min

(51) The DSC3 method is used to simulate a laser sintering process with a processing temperature of 215° C. In the segment ]2[the sample is heated up to the processing temperature. In the segments ]3[ and ]4[ the effect of a laser beam on the sample is simulated by very rapid heating to a temperature above the processing temperature immediately followed by very rapid cooling, as is the case with laser sintering. In the segment ]5[, whose final temperature is below the glass transition temperature of the sample, slow cooling takes place in order to simulate the cooling process in the course of laser sintering. In the segment ]8[ the sample is analyzed in the course of a new heating. The conditions of the DSC3 method are described in Table 3.

(52) TABLE-US-00003 TABLE 3 Heating/cooling Start- Final- rate [° C./min] Operating Temperature Temperature or holding Segment mode [° C.] [° C.] time [min] ]1[ isothermal 0 0 3 min ]2[ dynamic 0 215  20° C./min ]3[ dynamic 215 300  50° C./min ]4[ dynamic 300 215 −50° C./min ]5[ dynamic 215 150 −0.1° C./min  ]6[ dynamic 150 0 −20° C./min ]7[ isothermal 0 0 3 min ]8[ dynamic 0 300  20° C./min

(53) The DSC4 method is used to simulate a laser sintering process with a processing temperature of 250° C., whereby the sample is only partially melted. In the segment ]2[ the sample is heated to the processing temperature. In the segments ]3[ and ]4[, the short-term effect of a laser beam on the sample is simulated by very rapid heating to a temperature above the processing temperature immediately followed by very rapid cooling, as is the case with laser sintering. The final temperature of the segment ]3[ is lower than in the case of the DSC2 method, at which the processing temperature is also 250° C. The temperature of the laser beam is also lower than in the case of the DSC2 method. In the segment ]5[, whose final temperature is below the glass transition temperature of the sample, slow cooling takes place in order to simulate the cooling process in the course of laser sintering. In the segment ]8[ the sample is analyzed in the course of a new heating. The conditions of the DSC4 method are described in Table 4.

(54) TABLE-US-00004 TABLE 4 Heating/cooling Start- Final- rate [° C./min] Operating Temperature Temperature or holding Segment mode [° C.] [° C.] time [min] ]1[ isothermal 0 0 3 min ]2[ dynamic 0 250  20° C./min ]3[ dynamic 250 275  50° C./min ]4[ dynamic 275 250 −50° C./min ]5[ dynamic 250 150 −0.1° C./min  ]6[ dynamic 150 0 −20° C./min ]7[ isothermal 0 0 3 min ]8[ dynamic 0 350  20° C./min

(55) The conditions of the DSC6 method are described in Table 5.

(56) TABLE-US-00005 TABLE 5 Heating/cooling Start- Final- rate [° C./min] Operating Temperature Temperature or holding Segment mode [° C.] [° C.] time [min] ]1[ isothermal 0 0 3 min ]2[ dynamic 0 360 20° C./min ]3[ isothermal 360 360 3 min ]4[ dynamic 360 0 −1° C./min ]5[ isothermal 0 0 3 min ]6[ dynamic 0 360 20° C./min

(57) 2. Optical Methods to Determine Particle Size and Shape:

(58) The optical methods used to determine particle size and shape are based on the ISO 13322-2 standard. The sample is dispersed in a liquid medium. The liquid medium is pumped so that it flows past a calibrated optical unit. For evaluation, 10000 individual images are taken. The particle sizes and shapes are determined on the basis of defined measuring parameters. Determined parameters are the minimum chord length (given as d10, d50 and d90, i.e. as 10% quantile, 50% quantile and 90% quantile of the volumetric particle size distribution) as a measure for the particle sizes and the sphericity SPHT as a roundness measure according to the following definition:

(59) $\mathrm{SPHT}=\frac{4.Math.\pi .Math.A}{U^2}$

(60) U is the measured circumference of the particle projection. A is the measured area of the particle projection. The mean sphericity of all measured particles is given. According to the definition, the result for a sphere is SPHT=1. The more the shape of a particle deviates from the shape of a sphere, the smaller the value for SPHT.

(61) From the quantiles determined as described above, the distribution width of the particle size distribution can be calculated according to the following formula:

(62) $\mathrm{Distribution}\mathrm{width}=\frac{d90-d10}{d50}$

(63) To perform the optical methods, distilled water with the X-Flow module is placed and degassed in a reservoir in a Camsizer XT measuring instrument (Retsch Technology, software version 6.0.3.1008) with the X-Flow module. The surface density of measured particles/air bubbles is less than 0.01%. A sample quantity of approximately 1 to 3 mg of the powdery material to be examined is dispersed in 2 to 3 mL of a solution of Triton X in water. The concentration of Triton X in the solution is 3 mass percent. The dispersed sample is slowly dripped into the distilled water in the receiver until a measured areal density of 0.4% to 0.6% is obtained. The measurement is started and repeated several times to produce a statistical measured value.

EXAMPLES

(64) Several examples of this invention are described below. The examples described below serve to illustrate this invention and therefore do not limit the scope of this invention in any way. For the person skilled in the art, it is obvious in the context of the entire disclosure that the examples described below can be rearranged and modified. The characteristics of the individual examples can, where possible, be combined as desired.

Examples V1 and V2

(65) In the case of examples V1 and V2, the powdery material is a polyetherimide which contains repeating units according to the formula

(66) ##STR00031##

(67) SABIC distributes the polyetherimide used as the starting material under the trade names “Ultem® 1000”, “Ultem® 1010” and “Ultem® 1040”. The products sold under the trade names mentioned differ in the molecular weight of the polyetherimide molecules; this is higher for “Ultem® 1000” than for “Ultem®1010” and higher for “Ultem® 1010” than for “Ultem® 1040”.

(68) The polyetherimide, which basically has the property of melt-amorphousness and is therefore initially completely amorphous or substantially amorphous, was dissolved in dichloromethane so that a solution with 20 mass percent polyetherimide was obtained. To prepare the solution, polyetherimide in powder or granulated form was preferably treated with dichloromethane. A solution of a protective colloid of the polyvinyl alcohol type in distilled water with a protective colloid concentration of 5% by mass was added at room temperature. The volume ratio between the polyetherimide solution and the protective colloid solution was 1:3.3. An emulsion was produced by stirring with a vane stirrer, for example at 450 or 600 rounds per minute. Dichloromethane was distilled off by applying a vacuum and heating for 3 to 5 hours. The dispersion formed was stirred. The precipitated polymer was filtered off, washed with warm water and dried at 150° C. in a nitrogen atmosphere in a circulating air furnace. The powdery material produced in this way has a very round shape (i.e. a sphericity close to 1).

(69) The examples V1 and V2 differ with regard to the production of the powdery material in that in the case of example V1 the vane stirrer was operated at a stirring rate of 600 rounds per minute, while in the case of example V2 it was operated at a stirring rate of 450 rounds per minute.

(70) Table 6 shows the results obtained by DSC and optical methods for samples of powdery material obtained from “Ultem® 1040” according to examples V1 and V2. The values are given for the melting point T.sub.m and the specific melting enthalpy ΔH.sub.m determined by the DSC1 method. Values for particle size and SPHT determined by optical methods are also given. The starting material used was a polyetherimide sold under the trade name “Ultem® 1040”.

(71) TABLE-US-00006 TABLE 6 T.sub.m ΔH.sub.m Particle size [μm] Example Polymer [° C.] [J/g] d10 d50 d90 SPHT V1 Ultem 1040, SABIC 273 3.5 36 83 150 0.98 V2 Ultem 1040, SABIC 290 2.0 42 144 227 0.98

(72) The fact that the stirring rate of the vane stirrer has a significant influence on the particle size can be seen from the values given in Table 6: faster stirring can therefore lead to smaller particle size and changed particle size distribution.

(73) FIG. 6 shows a microscopic image of the powdery material produced according to example V2.

(74) FIG. 7 shows DSC curves obtained for example V1 using the DSC1 method. The highest of the three curves corresponds to the segment ]2[ (heating), the lowest curve corresponds to the segment ]4[ (cooling), the middle curve corresponds to the segment ]6[ (heating). The uppermost curve shows a melting peak corresponding to a melting point of T.sub.m=273° C. and a specific melting enthalpy of ΔH.sub.m=3.5 J/g, i.e. the sample of the powdery material produced was initially (at the beginning of the segment ]2[) at least partially semi-crystalline. The mean curve shows no melt peak, i.e. the sample was substantially amorphous or completely amorphous at the beginning of the segment ]6[. It follows from this that the initially at least partially semi-crystalline sample solidified after initial melting (segment ]2[) during cooling (segment ]4[) not in the form of a semi-crystalline material but in the form of a substantially amorphous or completely amorphous material. Powdery material produced according to example V1 thus loses its initially present crystalline part due to melting, i.e. it solidifies during cooling in such a way that the crystalline part present at the beginning of the segment ]2[ does not form again or does not form again to a substantial extent. The property of melt-amorphousness, which originally existed by nature for the polymer, thus reappears after the procedure according to the invention has been carried out.

(75) FIG. 8 shows the curve corresponding to the segment ]8[, which was obtained for another sample of the powdery material according to example V1 using the method DSC2. The curve shows no melt peak. Since the DSC2 method simulates the laser sintering of an object and the segment ]8[ represents an analysis of this object, it follows from the absence of the melting peak that an object made of the powdery material produced, which is initially at least semi-crystalline, by means of laser sintering is made of an substantially amorphous or completely amorphous material.

(76) The DSC curves obtained for the powdery material according to example V2 by means of methods DSC1 and DSC2 have at least qualitatively similar properties to the DSC curves shown in FIG. 7 and FIG. 8 for example V1. In particular, even in the case of example V2, the curve corresponding to segment ]2[ of method DSC1 has a melting peak which the curves corresponding to segments ]6[ of method DSC1 and ]8[ of method DSC2 do not have. Therefore, it can also be concluded for example V2 that the powdery material was at least partially semi-crystalline before the first melting and substantially amorphous or completely amorphous after the re-solidification, i.e. solidified after the first melting not in the form of a semi-crystalline material but in the form of a substantially amorphous or completely amorphous material. The powdery material produced according to example V2 loses its initially existing crystalline part due to the melting. Furthermore, it can be concluded that an object made of the initially at least partially semi-crystalline powdery material according to Example V2 by laser sintering consists of a substantially amorphous or completely amorphous material.

Examples V3 to V8

(77) The production of powdery material according to the examples V3 to V8 corresponded, apart from the fact that an additive was dispersed in the polymer solution, to the production of powdery material according to the examples V1 and V2 described in detail above. In the case of the examples V3, V5, V7 and V8, the vane stirrer was operated at a stirring rate of 600 rounds per minute, while in the case of the examples V4 and V6, it was operated at a stirring rate of 450 rounds per minute.

(78) The additive was carbon black particles (V3 to V6) or fumed silica (V7 and V8). Nanoparticles were preferred as additives. The quantities of the additive dispersed in the polymer solution were chosen differently as desired.

(79) Table 7 shows results obtained by the DSC1 method (T.sub.m and ΔH.sub.m) and by optical methods (particle size and SPHT) for samples of powdery material according to the examples V3 to V8. Polyetherimide with the trade names “Ultem® 1040” (V3 to V7) and “Ultem® 1000” (V8) was used.

(80) TABLE-US-00007 TABLE 7 T.sub.m ΔH.sub.m Particle size [μm] Example Additive [° C.] [J/g] d10 d50 d90 SPHT V3 1. quantity of 275 3.2 10 35 88 0.95 carbon black V4 1. quantity of 292 1.2 36 130 271 0.97 carbon black V5 2. quantity of 280 1.1 15 28 41 0.94 carbon black V6 2. quantity of 292 1.3 27 93 252 0.97 carbon black V7 1. quantity of 290 2.5 10 40 131 0.93 fumed silica V8 2. quantity of 298 1.0 19 41 68 0.96 fumed silica

(81) The fact that the stirring rate of the vane stirrer has an influence on the particle size can be seen from the values given in Table 7: Faster stirring can lead to smaller particle size and changed particle size distribution as shown by the comparison of V3 with V4 and the comparison of V5 with V6. The variable amount of the additive dispersed in the polymer solution has an influence on the melting point, the specific melting enthalpy and the particle size, as can also be seen from the values given in Table 7.

(82) FIG. 9 shows DSC curves obtained for example V3 using the DSC1 method. The uppermost curve corresponding to segment ]2[ shows a melting peak, i.e. the sample of the powdery material produced was initially (at the beginning of segment ]2[) at least partially semi-crystalline. The mean curve shows no melt peak, i.e. the sample was substantially amorphous or completely amorphous at the beginning of segment ]6[. It follows from this that the initially at least partially semi-crystalline sample solidified after initial melting (segment ]2[) during cooling (segment ]4[) not in the form of a semi-crystalline material but in the form of a substantially amorphous or completely amorphous material. Powdery material produced according to example V3 thus loses its initially present crystalline part due to melting, i.e. it solidifies during cooling in such a way that the crystalline part present at the beginning of the segment ]2[ does not form again or does not form again to a substantial extent.

(83) FIG. 10 shows the curve corresponding to the segment ]8[ obtained for another sample of the powdery material according to example V3 using the DSC2 method. The curve shows no melt peak. It follows from this that an object made of the produced powdery material, which is initially at least semi-crystalline, by laser sintering, consists of a substantially amorphous or completely amorphous material.

(84) The DSC curves obtained for the powdery material according to the examples V4 to V8 by means of the methods DSC1 and DSC2 show at least qualitatively similar properties as the DSC curves shown in FIG. 9 and FIG. 10 for the example V3. In particular, even in the case of examples V4 to V8, the curve corresponding to segment ]2[ of method DSC1 has a melting peak which the curves corresponding to segments ]6[ of method DSC1 and ]8[ of method DSC2 do not have. Therefore, it can also be concluded for the examples V4 to V8 that the powdery material was at least partially semi-crystalline before the first melting—also with the addition of functional additives—and substantially amorphous or completely amorphous after the re-solidification, i.e. after the first melting it did not solidify in the form of a semi-crystalline material but in the form of an substantially amorphous or completely amorphous material. Furthermore, it can be concluded that an object made from the initially at least partially semi-crystalline powdery material according to the examples V4 to V8 by means of laser sintering consists of a substantially amorphous or completely amorphous material.

Examples V9 to V11

(85) The production of powdery material according to examples V9 to V11, apart from the fact that a polycarbonate was used as the polymer and drying was carried out in a nitrogen atmosphere in a convection furnace at 130° C., corresponded to the production of powdery material according to examples V1 and V5 described in detail above. The vane stirrer was operated at a stirring rate of 600 rounds per minute.

(86) The polycarbonates used as starting materials for the production of the powdery material are marketed by SABIC under the trade names “RMC 8089” (examples V9 and V10) and “Lexan® 143R” (example V11).

(87) In the case of example V10, unlike examples V9 and V11, an additive was dispersed in the polymer solution. For example, the additive consists of carbon black particles in the desired quantity.

(88) Table 8 shows results obtained by the DSC1 method (T.sub.m and ΔH.sub.m) and by optical methods (particle size and SPHT) for samples of the powdery material according to examples V9 to V11.

(89) TABLE-US-00008 TABLE 8 T.sub.m ΔH.sub.m Particle size [μm] Example Polymer [° C.] [J/g] d10 d50 d90 SPHT V9  RMC 8089, 240 25 20 38 62 0.93 SABIC V10 RMC 8089, 233 25 13 28 46 0.94 SABIC V11 Lexan 143R, 290 50 — — — — SABIC

(90) A comparison of the specific melting enthalpy values determined for the examples V1 to V11 shows that higher values can be expected for the specific melting enthalpy when using polycarbonates than for polyetherimides.

(91) FIG. 11 shows DSC curves obtained for example V10 using the DSC1 method. The uppermost curve, corresponding to segment ]2[, shows a melting peak, i.e. the sample of the powdery material produced was initially—and also with the addition of functional additives—at least partially semi-crystalline (at the beginning of segment ]2[). The mean curve shows no melt peak, i.e. the sample was substantially amorphous or completely amorphous at the beginning of segment ]6[. It follows from this that the initially at least partially semi-crystalline sample solidified after initial melting (segment ]2[) during cooling (segment ]4[) not in the form of a semi-crystalline material but in the form of a substantially amorphous or completely amorphous material. Thus, powdery material produced according to example V10 loses its initially present crystalline part due to melting, i.e. it solidifies during cooling in such a way that the crystalline part present at the beginning of the segment ]2[ does not form again or does not form again to a substantial extent.

(92) FIG. 12 shows the curve corresponding to the segment ]8[ obtained for another sample of the powdery material according to example V10 using the DSC3 method. The curve shows no melt peak. It follows from this that an object made of the produced powdery material, which is initially at least semi-crystalline, by laser sintering, consists of a substantially amorphous or completely amorphous material.

(93) The DSC curves obtained for the powdery material according to the V9 and V11 examples using the DSC1 and DSC3 methods have at least qualitatively similar properties to the DSC curves shown in FIG. 11 and FIG. 12 for the V10 example. In particular, even in the case of examples V9 and V11, the curve corresponding to segment ]2[ of method DSC1 has a melting peak which the curves corresponding to segments ]6[ of method DSC1 and ]8[ of method DSC2 do not have. Therefore, it can also be concluded for the examples V9 and V11 that the powdery material was at least partially semi-crystalline before the first melting and substantially amorphous or completely amorphous after the re-solidification, i.e. after the first melting (segment ]2[) it did not solidify in the form of a semi-crystalline material but in the form of a substantially amorphous or completely amorphous material during the cooling (segment ]4[). The powdery material produced according to the examples V9 and V11 thus loses its initially present crystalline portion through melting. Furthermore, it can be concluded that an object made of the initially at least semi-crystalline powdery material according to the examples V9 and V11 by laser sintering is made of a substantially amorphous or completely amorphous material.

Examples V12 to V19

(94) The production of powdery material according to the examples V12 to V15 and V19 corresponds, apart from the fact that polycarbonate and polyetherimide were dissolved together in dichloromethane and the precipitated polymer or polyblend was dried in a nitrogen atmosphere in a convection furnace at 130° C., to the production of powdery material described in detail above according to example V1. The vane stirrer was operated at a stirring rate of 600 rounds per minute.

(95) Polycarbonate and polyetherimide were used in a mass ratio of 1:1 (examples V12 and V13), 2:1 (example V14), 1:2 (example 15) and 2:3 (example V19). The V12 and V13 examples differ in the rate at which dichloromethane was distilled, V13 had a higher rate than V12, so that the DSC curve for V13 has a peak at 245° C. (see FIG. 13) which corresponds to the kinetically preferred crystallite structure and which the DSC curve does not have for V12.

(96) The polycarbonate used as starting material and the polyetherimide used as starting material are sold by SABIC under the trade names “Lexan® 143R” and “Ultem® 1000” respectively.

(97) Polycarbonate and polyetherimide were dissolved together in dichloromethane to produce the powdery material. The concentration of the solution of polycarbonate and polyetherimide was 20 mass percent. The powdery material was precipitated from the solution. At least in part, the precipitated powdery material was a polyblend of polycarbonate and polyetherimide.

(98) For the production of the powdery material, the powdery material was tempered according to example V15 in the case of examples V16 to V18. For tempering, the powdery material was placed in an aluminum shell in a layer about 1 to 2 cm thick and the aluminum shell was closed with a perforated aluminum lid in a convection furnace (manufacturer: Hereaus) the powdery material was tempered under nitrogen atmosphere (inflow: 1.5 m.sup.3/h nitrogen with a purity of >99%). The furnace was heated from room temperature to 200° C. within one hour. The furnace was then heated to the target temperature (e.g. 220° C., 240° C., 250° C.) within one hour. The target temperature was maintained for another hour. Natural cooling in the furnace to below 60° C. then followed. The powdery material was sieved. The target temperature was 220° C. (example V16), 240° C. (example V17) or 250° C. (example V18).

(99) Table 9 shows results obtained using the DSC1 method (T.sub.m and ΔH.sub.m) and optical methods (particle size and SPHT) for samples of powdery material according to the examples V12 to V19. If a double peak is present, as is the case with the DSC curves corresponding to the segment ]2[ for the examples V13 to V15 and V19, the melting point and the specific melting enthalpy are given in Table 9 for each of the two peaks (referred to as P1 and P2) of the double peak within a table field.

(100) TABLE-US-00009 TABLE 9 T.sub.m ΔH.sub.m Particle size [μm] Example Polymers [° C.] [J/g] d10 d50 d90 SPHT V12 Lexan 280 15 7 24 67 0.91 143R + Ultem 1000 (1:1) V13 Lexan 245 (P1) 6 (P1) 7 32 147 0.89 143R + 273 (P2) 8 (P2) Ultem 1000 (1:1) V14 Lexan 245 (P1) 10 (P1) — — — — 143R + 278 (P2) 8 (P2) Ultem 1000 (2:1) V15 Lexan 247 (P1) 7 (P1) — — — — 143R + 269 (P2) 4 (P2) Ultem 1000 (1:2) V16 V15, 252 27 — — — — tempered at 220° C. V17 V15, 266 26 — — — — tempered at 240° C. V18 V15, 273 18 — — — — tempered at 250° C. V19 Lexan 243 (P1) 4 (P1) 9 20 54 0.91 143R + 262 (P2) 4 (P2) Ultem 1000 (2:3)

(101) FIG. 13 shows DSC curves obtained for example V13 using the DSC1 method. The uppermost curve corresponding to segment ]2[ has a double peak corresponding to two melting peaks, i.e. the sample of the powdery material produced was initially (at the beginning of segment ]2[) at least partially semi-crystalline. The mean curve shows no melt peak, i.e. the sample was substantially amorphous or completely amorphous at the beginning of segment ]6[. It follows from this that the initially at least partially semi-crystalline sample solidified after initial melting (segment ]2[) during cooling (segment ]4[) not in the form of a semi-crystalline material but in the form of a substantially amorphous or completely amorphous material. Powdery material produced according to example V13 thus loses its initial crystalline part due to melting, i.e. it solidifies during cooling in such a way that the crystalline part present at the beginning of the segment ]2[ does not form again or does not form again to a substantial extent. Furthermore, it can be seen in FIG. 13 that the uppermost curve shows three glass transitions, one for the polycarbonate, one for the polyetherimide and a mixed glass transition. From this it can be concluded that a polyblend with several phases is partially present. The middle curve shows only the mixed glass transition.

(102) FIG. 14 shows the curve corresponding to the segment ]8[ obtained for another sample of the powdery material according to example V13 using the DSC2 method. The curve shows no melt peak. It follows from this that an object made of the powdery material produced, which is initially at least semi-crystalline, by laser sintering is made of a substantially amorphous or completely amorphous material. Furthermore, only the glass transitions for polycarbonate and polyetherimide are visible in FIG. 14, but no glass transition for the polyblend, which indicates that in an object produced from the produced powdery material by laser sintering, the polyblend is substantially segregated and thus a polyphase polyblend is present.

(103) In the case of examples V12 and V14 to V19, the curve corresponding to segment ]2[ of method DSC1 has melting peaks (in the form of a double peak) which the curves corresponding to segments ]6[ of method DSC1 and ]8[ of method DSC2 do not have. Therefore, it can also be concluded for the examples V12 and V14 to V19 that the powdery material was at least partially semi-crystalline before the first melting and substantially amorphous or completely amorphous after the re-solidification, i.e. solidified after the first melting not in the form of a semi-crystalline material but in the form of a substantially amorphous or completely amorphous material. The powdery material produced according to the examples V12 and V14 to V19 thus loses its initially present crystalline portion as a result of melting. Furthermore, it can be concluded that an object made of the initially at least semi-crystalline powdery material according to the examples V12 and V14 to V19 by means of laser sintering consists of a substantially amorphous or completely amorphous material.

(104) FIG. 15 shows DSC curves obtained for example V17 using the DSC1 method. The uppermost curve, corresponding to segment ]2[, has a single melt peak and no double peak.

(105) A comparison of the values given for the example V15 on the one hand and the examples V16 to V18 in Table 9 shows that the melting enthalpy ΔH.sub.m can be significantly increased by tempering. This reduces, for example, the sticking together of the powder particles. In addition, tempering shifts the melting point to a higher temperature, enabling a higher processing temperature. At the same time, the half-width of the melting peak may be reduced.

Examples V20 to V23

(106) A polyetherimide preferably in powdery or granulated form was dissolved in N,N-dimethylacetamide to give a solution of 5 mass percent polyetherimide. An additive was dispersed in the polymer solution. The additive was carbon black particles in the desired amount. In particular, nanoparticles were used as additives. The polymer solution was slowly added at room temperature to a liquid known as a “non-solvent” in which the N,N-dimethylacetamide is soluble and in which the polyetherimide is insoluble or poorly soluble. A vane stirrer was used to stir at 250 rounds per minute. After dropping, the volume ratio between N,N-dimethylacetamide and the non-solvent was 1:3.3. By dropping the polymer solution into the non-solvent, the polyetherimide precipitated from the solution. The precipitated polymer was filtered off, washed with warm water and dried at 150° C. in a nitrogen atmosphere in a convection furnace.

(107) Polyetherimides suitable as starting materials are marketed by SABIC under the trade names “Ultem® 1000”, “Ultem® 1010” and “Ultem® 1040”. Ultem® 1040 was used in the examples.

(108) The following non-solvent materials were used: ethyl acetate (example V20), acetone (example V21), 96% ethanol (example V22) and distilled water (example V23).

(109) Table 10 shows results obtained using the DSC1 method (T.sub.m and ΔH.sub.m) and optical methods (particle size and SPHT) for samples of powdery material according to the examples V20 to V23.

(110) TABLE-US-00010 TABLE 10 T.sub.m ΔH.sub.m Particle size [μm] Example Non-solvent [° C.] [J/g] d10 d50 d90 SPHT V20 ethyl acetate 290 2.2 20 42 69 0.81 V21 Acetone 291 1.2 12 33 62 0.80 V22 Ethanol 96 % 289 1.1 8 22 40 0.83 V23 distilled water 287 1.2 7 21 38 0.84

(111) FIG. 16 shows DSC curves obtained for example V20 using the DSC1 method. The uppermost curve corresponding to segment ]2[ has a melting peak, i.e. the sample of the powdery material produced was initially (at the beginning of segment ]2[) at least partially semi-crystalline. The mean curve shows no melt peak, i.e. the sample was substantially amorphous or completely amorphous at the beginning of segment ]6[. It follows from this that the initially at least partially semi-crystalline sample solidified after initial melting (segment ]2[) during cooling (segment ]4[) not in the form of a semi-crystalline material but in the form of a substantially amorphous or completely amorphous material. The powdery material produced according to example V20 thus loses its initially present crystalline part due to melting, i.e. it solidifies during cooling in such a way that the crystalline part present at the beginning of the segment ]2[ does not form again or does not form again to a substantial extent.

(112) Microscopic analysis of the powdery material shows that the particles are composed of partly aggregated primary particles and that the particles have a high surface area and a low sphericity. Particle size, aggregation tendency and surface roughness increase with decreasing polarity of the non-solvent. FIG. 17 shows a microscopic image of the powdery material produced according to example V20. FIG. 18 shows a microscopic image of the powdery material produced according to example V22. A comparison of these two images with the image shown in FIG. 6 of the powdery material produced according to example V2 shows that powder particles with considerably higher sphericity were obtained by the process used in example V2 to produce the powdery material than by the process used in examples V20 and V22.

Example V24

(113) The powdery material according to example V24 was produced and tempered like the powdery material according to example V17. However, the examination of the powdery material was carried out differently than in the case of example V17 using the DSC4 method. The DSC4 method simulates a laser sintering process in which the powdery material only partially melts.

(114) FIG. 19 shows DSC curves obtained for the V24 example using the DSC4 method. No crystallization was visible during cooling. In the segment ]8[ a melting peak corresponding to a melting point of T.sub.m=290° C. and a melting enthalpy of ΔH.sub.m=3.5 J/g can be recognized. For example V17, a melting peak at T.sub.m=266° C. and a melting enthalpy of ΔH.sub.m=26 J/g (see Table 9), i.e. a considerably higher value than 3.5 J/g, was detected. It follows from this that in the case of example V24, the first partial melting (segments ]2[ and ]3[) resulted in a reduction of the crystalline portion of the sample and that no crystallization occurred during cooling (segments ]4[, ]5[ and ]6[). This means that solidifying material did not solidify in the form of a semi-crystalline material but in the form of a substantially amorphous or completely amorphous material.

Example V25

(115) The powdery material according to example V25 is produced like the powdery material in example V1. However, the polyetherimide copolymer marketed by SABIC under the trade name Ultem® 5001 is used as the starting material.

(116) The analysis results from the article by K. M. NELSON et al. quoted above. By appropriate treatment, it is possible to achieve a crystallinity of up to 30% for the melt-amorphous material.

COMPARATIVE EXAMPLES

(117) The samples used for comparative experiments, which were not carried out according to the invention, were untreated powdery materials which, for example, were used as starting materials in the case of examples V1 and V2 or V11, i.e. these materials were not treated by dissolving them in a solvent such as dichloromethane or N,N-dimethylacetamide and precipitating them from this solution.

(118) FIGS. 20 and 21 show DSC curves from comparative experiments. FIG. 20 shows DSC curves for the polyetherimide, which was used as the starting material in examples V1 and V2, and FIG. 21 shows DSC curves for the polycarbonate, which was used as the starting material in example V11. The DSC curves were obtained using the DSC6 method. In contrast to the examples V1, V2 and V11, the uppermost curve corresponding to segment ]2[ has no melting peak, i.e. the sample of the powdery material was already substantially amorphous or completely amorphous at the beginning of segment ]2[. In contrast, the powdery material is selected or treated according to the invention in such a way that it is initially at least partially semi-crystalline. Also, the middle curve shows no melt peak, i.e. the sample was also at the beginning of the segment ]6[ substantially or completely amorphous. It follows from this that after the first melting (segment ]2[) the sample solidified again during cooling (segment ]4[) in the form of a substantially amorphous or completely amorphous material. In order to exclude the possibility that the solidification in amorphous form could only have taken place due to relatively rapid cooling, the cooling rate corresponding to segment ]4[was chosen relatively low (considerably lower than in method DSC1, see Table 1).

Example Series V26

(119) A non-crystalline melt-amorphous polyetherimide having repeating units according to the formula

(120) ##STR00032##

(121) which is marketed by SABIC under the trade name “Ultem® CRS5001”, has been subjected to a crystallization treatment in unground granular form by the action of at least 24 hours of dichloromethane. The almost complete crystallization after this period was demonstrated in preliminary tests by analysis of the granules using the DSC1 method. Longer residence times showed no increase in melt enthalpy.

(122) After crystallization had been completed, the non-solvent was removed and the crystallized polymer granulate was subjected to grinding on a Torbellino type pin mill under cooling. The product was fractionated using a turbo sieve with a mesh size of 75 μm. The screen passage was used as product.

(123) By varying the grinding parameters different products could be produced: Products P1, P2, and P3.

(124) In a comparative example, the same granulate Ultem CRS5001 was ground in amorphous form, without prior crystallization treatment. In contrast to the products P1 to P3, fractionation was carried out with the turbo sieve at a mesh size of 104 μm. In addition, before the analysis of the sample, a protective sieving was carried out with a vibrating sieve at 106 μm mesh size. The product of this grinding is referred to as P4 in the following.

(125) In a further modification, product P4 was then crystallized in dichloromethane to obtain product P5.

(126) Table 11 shows the particle size distribution and grain shape of the products obtained. It becomes clear that the grinding of the pre-crystallized material results in an even, narrow particle size distribution, independent of the selected grinding parameters. The grain shape is also comparable in all cases.

(127) On the other hand, the material that was ground in amorphous form is basically coarser and the grinding throughput in kg/h is reduced by about the factor XY compared to the pre-crystallized material. The latter has a negative effect on the economic efficiency of powder production. Grinding with a finer sieve showed no significant sieve passage. Mostly fibrous particles were formed, as they are still present in sample P4 (FIG. 22). Such fibrous particles lead to the formation of lumps, which lead to processing problems on the LS system and in particular have a negative effect on the powder application density due to deteriorated flow behavior. This is indicated by the bulk density according to DIN EN ISO 60, which is also included in Table 11. The amorphous ground powder P4 shows a significantly reduced bulk density compared to the samples P1 to P3 ground in semi-crystalline form. The post-crystallized material P5 also shows a significant increase in bulk density, which can be attributed to the detectable rounding effect caused by the solvent treatment (SPHT=0.91). A corresponding rounding effect can also be expected for semi-crystalline ground powder. A disadvantage for the amorphously ground, subsequently crystallized material P5, however, is the high distribution width and the high proportion of fine powder, which experience has shown can lead to problems during processing on LS systems. This effect is not to be expected to this extent in the post-crystallization of semi-crystalline ground powders, since the formation of the fine fraction is due in particular to the fibrous structures. The fibers, which have very small diameters, clump or break to very fine particles with diameters smaller than 10 μm.

(128) TABLE-US-00011 TABLE 11 d10 d50 d90 SPHT Bulk density Example [μM] [μM] [μM] [—] [g/100 cm.sup.3] P1 27 56 77 0.89 44.0 P2 24 49 74 0.89 46.0 P3 23 50 77 0.89 45.4 P4 24 56 103 0.86 41.0 P5 11 71 123 0.91 45.4

(129) FIG. 25 shows the first heating run (segment 2) of the various products P1 to P5, measured using the DSC1 method. As expected, the amorphous ground granulate (product P4) is also amorphous in the powder state. Depending on the grinding parameters, an increased melting enthalpy can be observed in the grinding of the crystallized granulate, P1 to P3, in ascending order. The exact values can be found in Table 12. The powder P5 crystallized after amorphous grinding shows the highest melting enthalpy. A corresponding melting enthalpy and melting temperature can also be expected during the post-crystallization of the semi-crystalline ground powder.

(130) The different powdery polymer materials P1 to P5 obtained in this way were then used for a laser sintering process under otherwise identical conditions. The processing was carried out on a modified EOS P396 laser sintering machine from EOS GmbH—Electro Optical Systems. In particular, the following parameters were selected for processing: Withdrawal chamber temperature: 180° C. Process chamber temperature: upper processing temperature Energy input during exposure with laser: 0.70 J/mm.sup.3

(131) The upper processing temperature was checked by checking the indentation of a drawn pair of tweezers in the powder bed at the appropriate temperature. If the tweezers do not sink into the powder bed and leave no (relevant) impression, the upper processing temperature is reached. Otherwise, the process chamber temperature is increased by 1-2° C., and after a defined number of layers, the powder bed is checked again until the expected effect occurs. At the upper processing temperature, there is also a homogeneous coating process during which there is no adhesion of the particles in the coater, as can be seen, for example, by the formation of stripes parallel to the coating direction within the new powder layer. The upper processing temperatures of the various products are also shown in Table 12. Block-shaped test specimens with the dimensions 20×4×16 (X×Y×Z) and modified tensile test specimens based on DIN EN ISO 527-2 type 1BB with a total length of 60 mm, a height of 2.5 mm and a width in the parallel specimen range of 4 mm in X orientation are produced. There is an obvious dependence of the maximum processing temperature on the enthalpy of the melt. A higher processing temperature is necessary in order to keep the required energy input by means of the laser radiation at a suitable level, on the one hand to obtain an economical processing process and on the other hand to achieve a complete melting of the powder with suitable bonding of the layers and the most possible pore-free solidification of the material without degrading the material. This relationship can be established by the tensile strength and elongation at break of laser-sintered specimens of the material as well as by thin sections of laser-sintered specimens. An exemplary thin section for the amorphously processed material P4 is shown in FIG. 23. The black areas within the white polymer matrix are air inclusions/pores which occur due to insufficient flow at too low a processing temperature. This is particularly noticeable by the unshapely shape of the inclusions of formed gas bubbles (round).

(132) In contrast, the invention material from the processing of P3 (FIG. 24) has significantly fewer inclusions. An examination of the tensile strengths in Table 12 also clearly shows that a higher processing temperature due to higher melting enthalpy has a beneficial effect on the component properties. However, it should also be noted that the melt viscosity determined in accordance with ISO 1133 for the material used was not in the preferred range at a test temperature of 360° C. and 5 kg load. A material with a lower viscosity but chemically identical structure, as marketed by Sabic under the name “Ultem® CRS5011”, should exhibit further improved processing. For example, a melt viscosity of 5 cm.sup.3/10 min for CRS5001 and a melt viscosity of 16 cm.sup.3/10 min for CRS5011 were obtained for exemplary batches.

(133) TABLE-US-00012 TABLE 12 Max. processing Tensile T.sub.g T.sub.m ΔH.sub.m temperature* strength Example [° C.] [° C.] [J/g] [° C.] [MPa] P1 217 256 3.6 254 16.9 P2 217 256 6.2 258 22.3 P3 217 256 9.8 262 24.5 P4 223 n/a n/a 252 13.5 P5 n/a 268 23.8 266 n/a *The maximum processing temperature at P1-P5 was determined by the pyrometer of the LS machine; due to the modification of the machine EOS P396 for applications >200° C. construction temperature with a reduction of installation space, this does not mean a quantitative value, but only a qualitative value.

(134) FIG. 26 shows the first heating run (segment 2) of the various components obtained from the products P1 to P5, measured using the DSC1 method. This makes it clear that the materials P1 to P5 solidify in amorphous form, independent of the initial crystallinity, i.e. that the materials are melt-amorphous.

(135) The results show significantly better effects if the powdery material was produced according to the invention method or if the powdery material had the invention properties.