EP3691900A1

EP3691900A1 - Sintered powder containing a near-infrared reflector for producing moulded bodies

Info

Publication number: EP3691900A1
Application number: EP18774081.6A
Authority: EP
Inventors: Claus Gabriel; Thomas Meier; Natalie Beatrice Janine Herle; Leander VERBELEN; Kara Ann NOACK
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2017-10-04
Filing date: 2018-10-01
Publication date: 2020-08-12
Also published as: JP7309699B2; CN111448072A; KR20200056454A; KR20240096728A; WO2019068658A1; US20200230875A1; JP2021508291A

Abstract

The invention relates to a method for producing a moulded body, according to which, in step i), a layer of a sintered powder (SP) containing at least one near-infrared reflector, inter alia, is provided, and in step ii), the layer provided in step i) is exposed. The invention also relates to a method for producing a sintered powder (SP), to the sintered powder (SP) that can be produced by said method, and to the use of a near-infrared reflector in a sintered powder (SP). The invention further relates to a moulded body that can be produced by the method according to the invention.

Description

The present invention relates to a method for the production of a shaped body, wherein in step i) a layer of a sintering powder (SP) containing inter alia at least one near-infrared reflector is provided and in step ii) the layer provided in step i) is exposed. Furthermore, the present invention relates to a method for producing a sintered powder (SP) and the sintered powder (SP) obtainable by this method and the use of a near-infrared reflector in a sintered powder (SP). Moreover, the present invention relates to a molded article obtainable by the process according to the invention.

Rapid deployment of prototypes is a common task in recent times. One method which is particularly suitable for this so-called "rapid prototyping" is selective laser sintering (SLS), in which a plastic powder in a chamber is selectively exposed to a laser beam, the powder melts, the molten particles run into each other and solidify again. Repeated application of plastic powder and subsequent exposure with a laser allows the modeling of three-dimensional moldings.

The process of selective laser sintering for the production of molded articles from pulverulent polymers is described in detail in US Pat. Nos. 6,136,948 and WO 96/06881.

The selective laser sintering is often too time-consuming for the production of a larger number of moldings, so that high-speed sintering (HSS) or the so-called Multijet Fusion Technology (MJF) from HP can be used to produce larger quantities of moldings. In high-speed sintering, by spraying an infrared-absorbing ink onto the component cross-section to be sintered and then exposing with an infrared radiator, a higher processing speed is achieved compared to selective laser sintering.

A disadvantage of the high-speed sintering, however, is that the powder should not sinter outside of the molded body cross-section to be sintered, nor should it stick together. Therefore, the lowest possible installation space temperature must be used during production. This often leads to the fact that the molded body does not fuse well in the Förmkörperquerschnitt to be sintered and / or a high component distortion results.

Even selective laser sintering often leads to component distortion. If, in addition to a pure polyamide or another pure semicrystalline polymer, further components are contained in the sintering powder, is the selective laser sintering often reduces the sintering window of the sintering powder. A reduction of the sintering window often leads to distortion of the moldings during production by selective laser sintering. By this delay, a use or further processing of the molded body is almost impossible. The delay can already be so strong during the production of the moldings that a further layer application is not possible and therefore the production process must be terminated.

The object underlying the present invention was therefore to provide a process for the production of moldings which does not or only to a small extent has the aforementioned disadvantages of the processes described in the prior art. The process should also be simple and inexpensive to carry out. This object is achieved by a method for producing a shaped body, comprising the steps of: i) providing a layer of a sintering powder (SP) which comprises the components (A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

(C) contains at least one near-infrared reflector, ii) exposing the layer of the sintering powder (SP) provided in step i).

It has surprisingly been found that a higher installation space temperature, in particular when the method according to the invention is a high-speed sintering method or a Multijet fusion method, can be used in the method according to the invention, than in methods as described in the prior art. As a result, the component melts better in the cross section to be sintered and the distortion is significantly reduced compared to methods as described in the prior art. In addition, the sintering powder (SP) used according to the invention has good thermooxidative stability, which results in good recyclability of the sintering powder (SP), ie good recyclability from the construction space.

In particular, the method according to the invention is also well suited as a selective laser sintering method, since the sintering powder (SP) used according to the invention has a broad sintering window. In addition, moldings which have good mechanical properties, in particular a high modulus and good tensile strengths, are obtained by the process according to the invention.

5 If the at least one near-infrared reflector is a color pigment or a dye, through-colored moldings are obtained which retain their color even during the grinding and / or polishing after their preparation.

If the at least one near-infrared reflector is a black pigment, particularly deep-black egg-colored shaped bodies are obtained in process 10 according to the invention. Such deep blackening is often difficult or impossible to achieve with sintered powders (SP) as described in the prior art.

The method according to the invention will be explained in more detail below.

15 step \)

In step i), a layer of the sintering powder (SP) is provided.

The layer of sintering powder (SP) can be provided by all methods known to those skilled in the art. Usually, the layer of sintering powder (SP) is provided in a construction space on a building platform. The installation space can optionally be tempered.

The installation space has, for example, a temperature which is 1 to 100 K (Kelvin), 25 preferably 5 to 50 K and particularly preferably 10 to 25 K below the melting point (T _M ) of the sintering powder (SP).

The installation space has, for example, a temperature in the range of 150 to 250 ° C, preferably in the range of 160 to 230 ° C and particularly preferably in the range of 30 170 to 210 ° C.

The provision of the layer of sintering powder (SP) can be carried out by all methods known to the person skilled in the art. For example, the layer of the sintering powder (SP) is provided by a squeegee or a roller in the thickness to be achieved in the installation space 35.

The thickness of the layer of sintering powder (SP) provided in step i) may be arbitrary. For example, it is in the range of 50 to 300 μηη, preferably in the range of 70 to 200 μηη and particularly preferably in the range of 90 to 150 μηη. Sintered powder (SP)

According to the invention, the sintered powder (SP) contains at least one partially crystalline polyamide as component (A), at least one amorphous polyamide as component (B) and at least one near-infrared reflector as component (C).

In the context of the present invention, the terms "component (A)" and "at least one partially crystalline polyamide" are used synonymously and therefore have the same meaning.

10

The same applies to the terms "component (B)" and "at least one amorphous polyamide". These terms are also used synonymously in the context of the present invention and therefore have the same meaning.

Accordingly, the terms "component (C)" and "at least one near-infrared reflector" are used synonymously in the context of the present invention and have the same meaning.

The sintering powder (SP) may contain the components (A), (B) and (C) in any desired amounts.

For example, the sintered powder (SP) contains in the range of 50 to 94.95% by weight of component (A), in the range of 5 to 40% by weight of component (B) and in the range of 0.05 to 10% by weight .-% of component (C), in each case based on the sum of 25 weight percent of components (A), (B) and (C), preferably based on the total weight of the sintering powder (SP).

Preferably, the sintering powder (SP) contains in the range of 60 to 94.9 wt .-% of component (A), in the range of 5 to 30 wt .-% of component (B) and in the range 30 from 0, 1 to 8 % By weight of component (C), in each case based on the sum of the percentages by weight of components (A), (B) and (C), preferably based on the total weight of the sintering powder (SP).

Most preferably, the sintering powder (SP) in the range of 70 to 35 contains 91.9% by weight of component (A), in the range of 8 to 25% by weight of component (B) and in the range of 0.1 to 5 wt .-% of component (C), in each case based on the sum of the weight percent of components (A), (B) and (C), preferably based on the total weight of the sintering powder (SP).

The present invention therefore also provides a process in which the sintering powder (SP) is in the range from 50 to 94.95% by weight of component (A), in the range from 5 to 40% by weight of component (B ) and in the range of 0.05 to 10 wt .-% of Component (C), in each case based on the total weight of the sintered powder (SP).

The sintering powder (SP) may further comprise at least one additive. For example, the at least one additive is selected from the group consisting of antinucleating agents, stabilizers, flow aids and end group functionalizers.

A suitable antinucleating agent is, for example, lithium chloride.

Suitable stabilizers are, for example, phenols, phosphites and copper stabilizers.

Suitable end group functionalizers are, for example, terephthalic acid, adipic acid and propionic acid.

Suitable flow aids are, for example, silicic acids or aluminum oxides. As a flow aid is preferred alumina. A suitable aluminum oxide is, for example, Aeroxide® Alu C from Evonik.

For example, the sintering powder (SP) contains in the range of 0.1 to 10 wt .-% of the at least one additive, preferably in the range of 0.2 to 5 wt .-% and particularly preferably in the range of 0.3 to 2.5 % By weight, in each case based on the total weight of the sintering powder (SP).

The present invention therefore also provides a process in which the sintering powder (SP) additionally contains in the range from 0.1 to 10% by weight of at least one additive selected from the group consisting of antinucleating agents, stabilizers and end group functionalizing, based on the Total weight of the sintering powder (SP).

Preferably, the sintering powder (SP) additionally contains at least one reinforcing agent. For example, the sintering powder (SP) contains in the range of 5 to 60 wt .-%, preferably in the range of 10 to 50 wt .-% and particularly preferably in the range of 15 to 40 wt .-% of at least one Verstärkungsmitteis, each based on the Total weight of the sintering powder (SP). The percentages by weight of components (A), (B) and (C) and, if appropriate, of the at least one additive and the at least one reinforcing agent usually add up to 100% by weight. "At least one reinforcing agent" in the context of the present invention means both exactly one reinforcing agent and a mixture of two or more reinforcing agents.

5

In the context of the present invention, a reinforcing agent is understood as meaning a material which improves the mechanical properties of shaped bodies produced by the process according to the invention compared to shaped bodies which do not contain the reinforcing agent.

10

Reinforcing agents as such are known to the person skilled in the art. For example, the at least one reinforcing agent may be spherical, platelet-shaped or fibrous.

Preferably, the at least one reinforcing agent is platelet-shaped or fibrous.

By "fibrous reinforcing agent" is meant a reinforcing agent in which the ratio of the length of the fibrous reinforcing agent to the diameter of the fibrous reinforcing agent is in the range of 2: 1 to

20 is 40: 1, preferably in the range of 3: 1 to 30: 1 and particularly preferably in the range of 5: 1 to 20: 1, wherein the length of the fibrous Verstärkungsmitteis and the diameter of the fibrous Verstärkungsmitteis be determined by microscopy by means of image analysis Samples after ashing, with at least 70,000 parts of the fibrous reinforcing agent evaluated after ashing

25 will be.

The length of the fibrous Verstärkungsmitteis is then usually in the range of 5 to 1000 μηη, preferably in the range of 10 to 600 μηη and particularly preferably in the range of 20 to 500 μηη, determined by microscopy with 30 image analysis after incineration.

The diameter is then for example in the range of 1 to 30 μηη, preferably in the range of 2 to 20 μηη and particularly preferably in the range of 5 to 15 μηη, determined by microscopy with image analysis after incineration.

35

The at least one reinforcing agent is platelet-shaped in a further preferred embodiment. In the context of the present invention, "platelet-shaped" is understood to mean that the particles of the at least one reinforcing agent have a ratio of diameter to thickness in the range from 4: 1 to 40: 1, determined by microscopy with image evaluation after ashing. Suitable reinforcing agents are known to the person skilled in the art and are selected, for example, from the group consisting of carbon nanotubes, carbon fibers, boron fibers, glass fibers, glass beads, silica fibers, ceramic fibers, basalt fibers, aluminum silicates, aramid fibers and polyester fibers.

Preferably, the at least one reinforcing agent is selected from the group consisting of aluminum silicates, glass fibers and carbon fibers.

More preferably, the at least one reinforcing agent is selected from the group consisting of glass fibers and carbon fibers. These reinforcing agents can also be aminosilane-functionalized.

Suitable silica fibers are, for example, wollastonite. Suitable aluminum silicates are known to those skilled in the art. As aluminum silicates compounds are referred to containing Al ₂ 0 ₃ and Si0 ₂ . Structurally, the aluminum silicates have in common that the silicon atoms are tetrahedrally coordinated by oxygen atoms and the aluminum atoms are octahedrally coordinated by oxygen atoms. Aluminum silicates may also contain other elements.

Preferred as aluminum silicates are phyllosilicates. Particularly preferred as aluminum silicates are calcined aluminum silicates, particularly preferred are calcined sheet silicates. The aluminum silicate may also be aminosilane-functionalized.

If the at least one reinforcing agent is an aluminum silicate, the aluminum silicate can be used in any desired form. For example, it can be used as pure aluminum silicate, as it is also possible that the aluminum silicate is used as a mineral. Preferably, the aluminum silicate is used as a mineral. Examples of suitable aluminosilicates are feldspars, zeolites, sodalite, sillimanite, andalusite and kaolin. Kaolin is preferred as aluminum silicate.

The present invention therefore also provides a process in which the sintering powder (SP) additionally contains kaolin as at least one reinforcing agent.

Kaolin belongs to the clay stones and contains essentially the mineral kaolinite. The molecular formula of kaolinite is Al ₂ [(OH) 4 / Si ₂ O ₅ ]. Kaolinite is a layered silicate. Kaolin usually contains, in addition to kaolinite, other compounds such as, for example, titanium dioxide, sodium oxides and iron oxides. Kaolin preferred according to the invention contains at least 98% by weight of kaolinite, based on the total weight of the kaolin. The sintering powder (SP) has particles. These particles have, for example, a size in the range from 10 to 250 μm, preferably in the range from 15 to 200 μm, particularly preferably in the range from 20 to 120 μm, and particularly preferably in the range from 20 to 110 μm.

The sintered powder (SP) according to the invention has, for example, a D10 value in the range from 10 to 60 μm,

a D50 value in the range of 25 to 90 μηη and

a D90 value in the range of 50 to 150 μηη.

The sintering powder (SP) according to the invention preferably has a D10 value in the range from 20 to 50 μm,

a D50 value in the range of 40 to 80 μηη and

a D90 value in the range of 80 to 125 μηη.

The present invention therefore also provides a process in which the sintering powder (SP) has a D10 value in the range from 10 to 60 μm,

a D50 value in the range of 25 to 90 μηη and

has a D90 value in the range of 50 to 150 μηη.

In the context of the present invention, the "D10 value" is understood as meaning the particle size at which 10% by volume of the particles, based on the total volume of the particles, is less than or equal to the D10 value and 90% by volume of the particles, based on the total volume of the particles are greater than the D10 value. By analogy, the "D50 value" is understood to mean the particle size at which 50% by volume of the particles, based on the total volume of the particles, is less than or equal to the D50 value and 50% by volume of the particles, based on the total volume the particles are greater than the D50 value. Accordingly, the "D90 value" is understood to mean the particle size at which 90% by volume of the particles, based on the total volume of the particles, is less than or equal to the D90 value and 10% by volume of the particles, based on the total volume of the particles greater than the D90 value. To determine the particle sizes, the sintered powder (SP) is suspended by means of compressed air or in a solvent, such as water or ethanol, and measured this suspension. The determination of the D10, D50 and D90 value takes place using laser diffraction using a Master Sizers 3000 from Malvern. The evaluation is carried out by means of Fraunhofer diffraction.

The sintered powder (SP) usually has a melting temperature (T _M ) in the range of 160 to 280 ° C. Preferably, the melting temperature (T _M ) of the sintering powder (SP) is in the range of 170 to 265 ° C and particularly preferably in the range of 175 to 245 ° C.

The subject matter of the present invention is therefore also a process in which the sintering powder (SP) has a melting temperature (T _M ) in the range from 160 to 280 ° C.

The melting temperature (T _M ) is determined within the scope of the present invention by means of Differential Scanning Calorimetry (DSC). A heating run (H) and a cooling run (K) are usually measured, each with a heating rate or cooling rate of 20 K / min. In this case, a DSC diagram, as shown by way of example in FIG. 1, is obtained. The melting temperature (T _M ) is then understood to be the temperature at which the melting peak of the heating run (H) of the DSC diagram has a maximum.

The sintered powder (SP) also usually has a crystallization temperature (T _c ) in the range of 120 to 250 ° C. The crystallization temperature (T _c ) of the sintering powder (SP) is preferably in the range from 130 to 240 ° C. and particularly preferably in the range from 140 to 235 ° C.

The present invention therefore also provides a process in which the sintering powder (SP) has a crystallization temperature (T _c ) in the range from 120 to 250 ° C. The crystallization temperature (T _c ) is determined in the context of the present invention by means of differential scanning calorimetry (DSC). In this case, usually a heating (H) and a cooling (K), each with a heating rate or cooling rate of 20 K / min, measured. In this case, a DSC diagram, as shown by way of example in FIG. 1, is obtained. The crystallization temperature (T _c ) is then the temperature at the minimum of the crystallization peak of the DSC curve.

The sintered powder (SP) also usually has a sintering window (W _S p). The sintering window (W _S p) is, as described below, the difference between the onset temperature of the melting (T _M ^onset ) and the onset temperature of the crystallization (T _c ^onset ) - The onset temperature of the melting (T _M ^onset ) and the onset temperature of crystallization (T _c ^onset ) are determined as described below. The sintering window (W _S p) of the sintering powder (SP) is for example in the range of 10 to 40 K (Kelvin), more preferably in the range of 15 to 35 K and particularly preferably in the range of 18 to 30 K.

The sintered powder (SP) preferably reflects radiation having a wavelength in the near infrared range. The wavelength of the near infrared region is usually in the range of 780 nm to 2.5 μm. The sintered powder (SP) preferably reflects radiation having a wavelength in the range from 780 nm to 2.5 μm to 20 to 95%, more preferably 25 to 93% and particularly preferably 30 to 91%.

The reflection of the sintering powder (SP) is determined with a PerkinElmer UV / VIS / NI R spectrophotometer Lambda 950 with 150 mm integrating sphere. The reference is Spektraion White Standard from Labsphere.

The sintering powder (SP) can be prepared by all methods known to those skilled in the art. For example, the components (A), (B) and (C) and optionally the at least one additive and the at least one reinforcing agent can be ground together.

The grinding can be carried out by all methods known to the person skilled in the art, for example the components (A), (B) and (C) and optionally the at least one additive and the at least one reinforcing agent are added to a mill and ground therein.

Suitable mills are all mills known to the person skilled in the art, for example classifier mills, counter-jet mills, hammer mills, ball mills, vibrating mills or rotor mills.

Milling in the mill can also be carried out by all methods known to those skilled in the art. For example, the grinding may take place under inert gas and / or under cooling with liquid nitrogen. Cooling with liquid nitrogen is preferred. The temperature during grinding is arbitrary, preferably the grinding is carried out at temperatures of liquid nitrogen. The temperature of the components during grinding then ranges, for example, from -40 to -30 ° C. Preferably, the components are first mixed together and then ground. The method for producing the sintered powder (SP) then preferably comprises the steps a) mixing the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

(C) at least one near-infrared reflector, b) grinding the mixture obtained in step a) to obtain the sintering powder (SP).

The present invention therefore also provides a process for producing a sintered powder (SP), comprising the steps of a) mixing the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

(C) at least one near-infrared reflector b) grinding the mixture obtained in step a) to obtain the sintering powder (SP).

In a further preferred embodiment, the process for producing the sintering powder (SP) comprises the following steps: ai) mixing the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

(C) at least one mineral flame retardant, bi) grinding the mixture obtained in step ai) to obtain a polyamide, bii) mixing the polyamide powder obtained in step bi) with a flow aid to obtain the sintering powder (SP).

Suitable flow aids are, for example, silicic acids or aluminum oxides. As a flow aid is preferred alumina. A suitable alumina is, for example, Aeroxide ^® Alu C from Evonik.

In the event that the sintering powder (SP) contains a flow aid, it is preferably added in process step bii). The sintering powder (SP) contains in one Embodiment 0.1 to 1 wt .-%, preferably 0.2 to 0.8 wt .-% and particularly preferably 0.3 to 0.6 wt .-% flow aid, in each case based on the total weight of the sintering powder (SP) and the Rieselhilfe. Another object of the present invention is therefore also a process in which step b) comprises the following steps: bi) grinding the mixture obtained in step a) to obtain a polyamide powder, bii) mixing the polyamide powder obtained in step bi) with a flow aid to obtain the sintering powder (SP).

Processes for compounding (for mixing) in step a) are known to those skilled in the art. For example, the mixing can be carried out in an extruder, particularly preferably in a twin-screw extruder.

The present invention therefore also provides a process for producing a sintered powder (SP), in which the mixing of the components in step a) takes place in a twin-screw extruder.

For milling in step b), the above-described embodiments and preferences with regard to grinding apply accordingly. A further subject of the present invention is therefore also the sintering powder (SP) obtainable by the process according to the invention.

In one embodiment of the present invention, in the sintering powder (SP), the component (C) is coated with the component (A) and / or the component (B).

The subject matter of the present invention is therefore also a process in which the component (C) in the sintering powder (SP) is coated with the component (A) and / or with the component (B). The component (C) is usually coated with the component (A) and / or the component (B), if the production of the sintering powder (SP) by a method comprising the above-described steps a) and b), if First, the components (A), (B) and (C) are compounded together. In a further embodiment of the present invention, the sintering powder (SP) is present as a mixture. In other words, in this embodiment, the component (C) is contained in the components (A) and (B). Component (C) is then usually present in addition to components (A) and (B). The component (C) is usually present in addition to the components (A) and (B) when, for the preparation of the sintering powder (SP), the components (A), (B) and (C) are ground together without prior compounding.

The present invention therefore also provides a process in which the sintering powder (SP) is present as a mixture. Of course, it is also possible that one part of component (C) is coated with component (A) and / or component (B) and that another part of component (C) does not react with component (A) and / or the component (B) is coated. Component (A)

According to the invention, component (A) is at least one partially crystalline polyamide.

In the context of the present invention, "at least one partially crystalline polyamide" means both exactly one semicrystalline polyamide and one mixture of two or more partially crystalline polyamides.

"Partially crystalline" in the context of the present invention means that the polyamide has a melting enthalpy ΔΗ2 _(Α) of greater than 45 J / g, preferably greater than 50 J / g and particularly preferably greater than 55 J / g, in each case measured by means differential scanning calorimetry (DSC) according to ISO 1 1357-4: 2014.

The at least one partially crystalline polyamide (A) according to the invention therefore usually has a melting enthalpy ΔΗ2 _(Α) of greater than 45 J / g, preferably greater than 50 J / g and particularly preferably greater than 55 J / g, measured in each case by means of dynamic Differential scanning calorimetry (DSC) according to ISO 1 1357-4: 2014. The at least one partially crystalline polyamide (A) according to the invention usually has a melting enthalpy ΔΗ2 _(Α) of less than 200 J / g, preferably less than 150 J / g and particularly preferably less than 100 J / g, in each case measured by differential scanning calorimetry (differential scanning calorimetry, DSC) according to ISO 1 1357-4: 2014.

Suitable semicrystalline polyamides (A) generally have a viscosity number (VZ _(A) ) in the range from 90 to 350 ml / g, preferably in the range from 100 to 275 ml / g and particularly preferably in the range from 1 10 to 250 ml / g, determined in a 0.5% strength by weight solution of 96% strength by weight sulfuric acid at 25 ° C., measured in accordance with ISO 307: 2013-8. The present invention thus also provides a process in which component (A) has a viscosity number (VZ _(A) ) in the range from 90 to 350 ml / g, determined in a 0.5% strength by weight solution of the component (A) in 96 wt .-% sulfuric acid at 25 ° C. The component (A) according to the invention usually has a melting temperature (T _M <A ₎ ). Preferably, the melting temperature (T _M <A ₎ ) of the component (A) is in the range of 170 to 280 ° C, more preferably in the range of 180 to 265 ° C and particularly preferably in the range of 185 to 245 ° C, determined according to ISO 1 1357-3: 2014.

The present invention thus also provides a process in which component (A) has a melting temperature (T _M <A ₎ ), the melting temperature (T _M <A ₎ ) being in the range from 170 to 280 ° C. Suitable components (A) have a weight-average molecular weight (M _{W (A)} ) in the range of 500 to 2,000,000 g / mol, preferably in the range of 10,000 to 90,000 g / mol, and more preferably in the range of 20,000 to 70,000 g / mol. The weight-average molecular weight (M _{W (A)} ) is determined by SEC-MALLS (Size Exclusion Chromatography-Multi-Angle Laser Light Scattering) according to Chi-san Wu "Handbook of size exclusion chromatography and related techniques", page 19.

For example, semicrystalline polyamides (A) which are derived from lactams having 4 to 12 ring members are suitable as the at least one semicrystalline polyamide (A). Furthermore, partially crystalline polyamides (A) are suitable, which are obtained by reacting dicarboxylic acids with diamines. As at least one semicrystalline polyamide (A) derived from lactam, there are exemplified polyamides derived from polycaprolactam, polycapryllactam and / or polylaurolactam.

In the event that at least one partially crystalline polyamide (A) is used which is obtainable from dicarboxylic acids and diamines, the dicarboxylic acids which can be used are alkanedicarboxylic acids having 6 to 12 carbon atoms. In addition, aromatic dicarboxylic acids are suitable.

By way of example, adipic acid, azelaic acid, sebacic acid and dodecanedicarboxylic acid may be mentioned here as dicarboxylic acids. Suitable diamines are, for example, alkanediamines having 4 to 12 carbon atoms and aromatic or cyclic diamines, such as m-xylylenediamine, di (4-aminophenyl) methane, di (4-aminocyclohexyl) methane, 2,2-di (4 -aminophenyl) propane or 2,2-di (4-aminocyclohexyl) propane.

Preferred as component (A) are polycaprolactam (polyamide 6) and copolyamide 6/66 (polyamide 6 / 6.6). Copolyamide 6/66 preferably has a content of from 5 to 95% by weight of caprolactam units, based on the total weight of copolyamide 6/66.

Also suitable as at least one partially crystalline polyamide (P) are polyamides which are obtainable by copolymerization of two or more of the monomers mentioned above and below or mixtures of several polyamides, the mixing ratio being arbitrary. Particularly preferred are mixtures of polyamide 6 with other polyamides, in particular copolyamide 6/66.

The following, non-exhaustive list contains the above-mentioned and other suitable semicrystalline polyamides (A) and the monomers contained. AB-polymers:

PA 4 pyrrolidone

PA 6 ε-caprolactam

PA 7 enantholactam

PA 8 capryllactam

PA 9 9-aminopelargonic acid

P 1 1 1 1 -aminoundecanoic acid

P 12 Laurinlactam AA / BB polymers:

PA 46 tetramethylenediamine, adipic acid

PA 66 hexamethylenediamine, adipic acid

PA 69 hexamethylenediamine, azelaic acid

PA 610 hexamethylenediamine, sebacic acid

PA 612 hexamethylenediamine, decanedicarboxylic acid

PA 613 hexamethylenediamine, undecanedicarboxylic acid

PA 1212 1, 12-dodecanediamine, decanedicarboxylic acid

PA 1313 1, 13-diaminotridecane, undecanedicarboxylic acid

PA 6T hexamethylenediamine, terephthalic acid

PA MXD6 m-xylyenediamine, adipic acid

PA 6/66 (see PA 6 and PA 66) PA 6/12 (see PA 6 and PA 12)

PA 6 / 6.36 ε-caprolactam, hexamethylenediamine, C ₃₆ -dimeric acid

PA 6T / 6 (see PA 6T and PA 6) Preferably component (A) is selected from the group consisting of PA 4, PA 6, PA 7, PA 8, PA 9, PA 1 1, PA 12, PA 46, PA 66, PA 69, PA 6.10, PA 6.12, PA 6.13, PA6 / 6.36, PA 12.12, PA 13.13, PA 6T, PA 6T / 6, PA MXD6, PA 6/66, PA 6/12 and copolyamides of these. The present invention therefore also provides a process in which component (A) is selected from the group consisting of PA 4, PA 6, PA 7, PA 8, PA 9, PA 1 1, PA 12, PA 46, PA 66, PA 69, PA 6.10, PA 6.12, PA 6.13, PA 6 / 6.36, PA 12.12, PA 13.13, PA 6T, PA6T / 6, PA MXD6, PA 6/66, PA 6/12 and copolyamides of these.

More preferably, component (A) is selected from the group consisting of polyamide 6, polyamide 6/66, polyamide 6:10 and polyamide 66.

Most preferably, component (A) is selected from the group consisting of polyamide 6 and polyamide 6/66.

Component (B)

Component (B) is at least one amorphous polyamide.

"At least one amorphous polyamide" in the context of the present invention means both exactly one amorphous polyamide and one mixture of two or more amorphous polyamides. "Amorphous" in the context of the present invention means that the polyamide is used in Differential Scanning Calorimetry (Differential Scanning Calorimetry; DSC), measured according to ISO 1 1357, has no melting point.

"No melting point" means that the enthalpy of fusion of the amorphous polyamide ΔΗ2 (Β) is less than 10 J / g, preferably less than 8 J / g, and most preferably less than 5 J / g, each measured by differential scanning calorimetry (DDK; Scanning Calorimetry, DSC) according to ISO 1 1357-4: 2014.

The inventive at least one amorphous polyamide (B) thus usually has a melting enthalpy ΔΗ2 _(Β) of less than 10 J / g, preferably less than 8 J / g and particularly preferably less than 5 J / g, respectively measured by Differential Scanning Calorimetry (DSC) according to ISO 1 1357-4: 2014.

Suitable amorphous polyamides generally have a viscosity number (VZ _(B) ) in the range of 60 to 200 ml / g, preferably in the range of 70 to 150 ml / g and particularly preferably in the range of 75 to 125 ml / g, determined in a 0.5 wt .-% solution of component (B) in 96 wt .-% sulfuric acid at 25 ° C according to ISO 307: 2013-08. The component (B) of the invention usually has a glass transition temperature (T _G <B)), wherein the glass transition temperature (T _G <B)) usually in the range of 100 to 180 ° C, preferably in the range of 1 10 to 160 ° C and particularly preferably in the range of 120 to 155 ° C, determined by means of ISO 1 1357-2: 2014.

Suitable components (B) have a weight-average molecular weight (M _{W (B)} ) in the range of 5,000 to 35,000 g / mol, preferably in the range of 10,000 to 30,000 g / mol, and more preferably in the range of 15,000 to 25,000 g / mol. The weight-average molecular weight is determined by SEC-MALLS (Size Excision Chromatography Multi-Angle Laser Light Scattering) according to Chi-San Wu, "Handbook of Size Excision Chromatography and the Related Techniques", page 19.

Component (B) is preferably an amorphous partially aromatic polyamide. Such amorphous partially aromatic polyamides are known to the person skilled in the art and are selected, for example, from the group consisting of PA6I / 6T, PA 61 and PA 6 / 3T.

The present invention therefore also provides a process in which component (B) is selected from the group consisting of PA 6I / 6T, PA 61 and PA 6 / 3T.

If polyamide 6I / 6T is used as component (B), this may contain any proportions of 6I and 6T units. Preferably, the molar ratio of 6I units to 6T units in the range of 1 to 1 to 3 to 1, more preferably in the range of 1, 5 to 1 to 2.5 to 1 and particularly preferably in the range of 1, 8 to 1 to 2.3 to 1.

The MVR (275 ° C / 5 kg) (melt volume-flow rate, MVR) of component (B) is preferably in the range of 50 ml / 10 min to 150 ml / 10 min, more preferably in the range of 95 ml / 10 min to 105 ml / 10 min.

The zero viscosity rate η ₀ (zero shear rate viscosity) of component (B) is, for example, in the range from 770 to 3250 Pas. The zero viscosity η ₀ (zero shear rate viscosity) is determined using a TA Instruments "DHR-1" rotational viscometer and a 25 mm diameter plate-and-plate geometry with a gap spacing of 1 mm., Unpetted samples of component (B) are at 80 for 7 days Dried under vacuum and then measured with time-dependent frequency sweep (sequence test) with an angular frequency range of 500 to 0.5 rad / s The following further measurement parameters were used: deformation: 1, 0%, measuring temperature: 240 ° C, measuring time: 20 minutes, preheating time after sample preparation: 1.5 minutes Component (B) has an amino end group concentration (AEG) which is preferably in the range from 30 to 45 mmol / kg and particularly preferably in the range from 35 to 42 mmol / kg.

To determine the amino end group concentration (AEG), 1 g of component (B) is dissolved in 30 ml of a phenol / methanol mixture (phenol: methanol 75:25 by volume) and then titrated potentiometrically with 0.2 N hydrochloric acid in water.

The component (B) has a carboxyl end group concentration (CEG) which is preferably in the range of 60 to 155 mmol / kg, and more preferably in the range of 80 to 135 mmol / kg.

To determine the carboxyl end group concentration (CEG), 1 g of component (B) is dissolved in 30 ml of benzyl alcohol. It is then titrated visually at 120 ° C with 0.05 N potassium hydroxide in water.

Component (C)

According to the invention, component (C) is at least one near-infrared reflector.

In the context of the present invention, "at least one near-infrared reflector" means both exactly one near-infrared reflector and one mixture of two or more near-infrared reflectors. <br/> <br/> A near-infrared reflector in the context of the present invention is understood as meaning a compound which has radiation with a Wavelength, which lies in the range of the near infrared, reflects.

The near infrared wavelength is generally in the range of 780 nm to 2.5 m. Component (C) reflects this radiation, preferably at least 60%, more preferably at least 65%, and most preferably at least 70%.

It is preferred that component (C) reflects radiation having a wavelength in the range from 780 nm to 2.5 μm to 50 to 99%, preferably 50 to 95% and in particular 55 to 92%.

The subject matter of the present invention is therefore also a method in which component (C) reflects radiation having a wavelength in the range from 780 nm to 2.5 μm to at least 60%.

The reflection is determined with a Lambda 950 PerkinElmer UV / VIS / NIR spectrophotometer with 150 mm integrating sphere. The reference is Spektraion White Standard from Labsphere.

As component (C), all the near-infrared reflectors known to those skilled in the art are suitable. Preference is given to near-infrared-reflecting pigments. Especially preferred are near-infrared reflecting black pigments. It goes without saying that the component (C) is different from the optionally contained in the sintering powder (SP) at least one additive and the at least one reinforcing agent.

The sintering powder (SP) preferably contains no component which reflects radiation with a wavelength in the range from 780 nm to 2.5 μm to at least 60%, more preferably at least 65% and particularly preferably at least 70%, except for the component ( C).

Further preferably, the sintering powder (SP) contains no component which reflects radiation having a wavelength in the range of 780 nm to 2.5 μm to 55 to 92 5, preferably 50 to 95% and particularly preferably 50 to 99%, except component (C).

In the context of the present invention, a near-infrared-reflecting pigment is understood as meaning a colorant which reflects radiation having a wavelength in the range of the near infrared and which is insoluble in components (A) and (B).

The present invention therefore also provides a process in which component (C) is selected from the group consisting of near-infrared-reflecting pigments. Suitable near-infrared reflecting pigments are, for example, iron chromium oxides, titanium oxide, perylene dyes or aluminum pigments.

Suitable near-infrared-reflecting black pigments are, for example, iron chromium oxides or perylene dyes.

Preferred near-infrared reflectors are selected from the group consisting of iron chromium oxides and perylene dyes. A preferred iron chromium oxide is obtainable, for example, under the trade name Sicopal Black® K0095 from BASF SE.

A preferred perylene dye is obtainable, for example, under the trade names Lumogen® Black K0087 and Lumogen® Black FK 4281 from BASF SE or the trade name Paliogen® Black S 0084 from BASF SE.

A preferred titanium dioxide is available, for example, under the trade name Kronos 2220® and the trade name Kronos 2222®, in each case from Kronos. A preferred aluminum pigment is available, for example, under the trade name IReflex® 5000 White from Eckart.

Component (C) is preferably not carbon black. The component (C) is furthermore preferably no kaolin.

The present invention therefore also provides a process in which component (C) does not comprise carbon black.

The present invention also provides a process in which component (C) does not comprise kaolin.

Step ii)

In step ii), the layer of the sintering powder (SP) provided in step i) is exposed.

Upon exposure, at least part of the layer of sintering powder (SP) melts. The melted sinter powder (SP) flows into each other and forms a homogeneous melt. After exposure, the melted part of the layer of sintering powder (SP) cools again and the homogeneous melt solidifies again.

For exposure, all methods known to those skilled in the art are suitable. Preferably, the exposure in step ii) takes place with a radiation source. The radiation source is preferably selected from the group consisting of infrared radiators and lasers. As infrared radiators, near-infrared radiators are particularly preferred.

The present invention therefore also provides a method in which the exposure in step ii) is carried out with a radiation source which is selected from the group consisting of lasers and infrared radiators.

Suitable lasers are known to the person skilled in the art and, for example, fiber lasers, Nd: YAG lasers (neodymium-doped yttrium aluminum garnet lasers) or carbon dioxide lasers.

If a laser is used as the radiation source during exposure in step ii), the layer of the sintering powder (SP) provided in step i) is usually exposed to the laser beam locally and for a short time. In this case, only the parts of the sintering powder (SP), which have been exposed by the laser beam, selectively melted. If a laser is used in step ii), the method according to the invention is also referred to as selective laser sintering. Selective laser sintering is known to those skilled in the art. If an infrared emitter, in particular a near-infrared emitter, is used as the radiation source during the exposure in step ii), the wavelength at which the radiation source emits is usually in the range from 780 nm to 1000 μm, preferably in the range from 780 nm to 50 μηη and in particular in the range of 780 nm to 2.5 μηη.

During exposure in step ii), the entire layer of the sintering powder (SP) is then usually exposed. In order for only the desired areas of the sintering powder (SP) to be melted on exposure, an infrared-absorbing ink (IR-absorbing ink) is usually applied to the areas which are to be melted.

The method for producing the shaped body then preferably comprises between step i) and step ii) a step i-1), applying at least one IR-absorbing ink to at least a portion of the layer of sintering powder (SP) provided in step i).

The subject matter of the present invention is therefore also a process in which, between step i) and step ii), a step i-1) applying at least one IR-absorbing ink to at least a portion of the layer of sintering powder (SP) provided in step i) becomes. A further subject of the present invention is therefore also a process for producing a shaped body, comprising the steps of i) providing a layer of a sintering powder (SP) comprising the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

I-1) applying at least one IR-absorbing ink to at least part of the layer of sintering powder (SP) provided in step i) ii) exposing the layer of sintering powder provided in step i) ( SP).

Suitable IR-absorbing inks are all IR-absorbing inks known to those skilled in the art, in particular IR-absorbing inks for high-speed sintering known to those skilled in the art.

IR-absorbing inks usually contain at least one absorber that absorbs IR radiation, preferably NIR radiation (near-infrared radiation). When the layer of the sintering powder (SP) is exposed in step ii), the absorption of the IR radiation, preferably the NIR radiation, by the IR absorber contained in the IR-absorbing inks results in the part of the layer of the sintering powder (SP) being to which the IR absorbing ink has been applied is selectively heated.

The IR-absorbing ink may contain a carrier liquid in addition to the at least one absorber. Suitable carrier liquids are known to the person skilled in the art and, for example, oils or solvents.

The at least one absorber, an absorber can be present dissolved or dispersed in the carrier liquid.

If the exposure in step ii) is carried out with a radiation source selected from infrared emitters and step i-1) is carried out, then the method according to the invention is also referred to as high-speed sintering or multijet-fusion method. These methods are known to those skilled in the art.

After the step ii), the layer of the sintering powder (SP) is usually reduced by the layer thickness of the layer of the sintering powder (SP) provided in step i). lowered and applied another layer of sintering powder (SP). This is then re-exposed according to step ii).

Thereby, on the one hand, the upper layer of the sintering powder (SP) bonds to the lower layer of the sintering powder (SP), and moreover, the particles of the sintering powder (SP) are fused together within the upper layer by melting.

In the process according to the invention, the steps i) and ii) and optionally i-1) can therefore be repeated.

By repeating the lowering of the powder bed, the application of the sintering powder (SP) and the exposure and thus the melting of the sintering powder (SP), three-dimensional molded bodies are produced. It is possible to produce moldings which, for example, also have cavities. An additional support material is not necessary because the unmelted sinter powder (SP) itself acts as a support material.

A further subject of the present invention is therefore also a shaped article obtainable by the process according to the invention.

Of particular importance in the process according to the invention is the melting range of the sintering powder (SP), the so-called sintering window (W _S p) of the sintering powder (SP). The sintering window (W _S p) of the sintering powder (SP) can be determined, for example, by differential scanning calorimetry (DSC).

In differential scanning calorimetry, the temperature of a sample, in this case a sample of the sintering powder (SP), and the temperature of a reference are changed linearly with time. For this purpose, the sample and the reference heat is supplied or removed from it. It determines the amount of heat Q necessary to keep the sample at the same temperature as the reference. The reference value used is the quantity of heat Q _R supplied or discharged to the reference. When the sample undergoes endothermic phase transformation, an additional amount of heat, Q, must be supplied to maintain the sample at the same temperature as the reference. If an exothermic phase transformation takes place, a quantity of heat Q has to be removed in order to keep the sample at the same temperature as the reference. The measurement provides a DSC diagram in which the amount of heat Q, which is supplied to the sample and discharged from it, is plotted as a function of the temperature T. Usually, a heating run (H) is first carried out during the measurement, that is, the sample and the reference are heated linearly. During the melting of the sample (solid-liquid phase transformation), an additional amount of heat Q must be supplied to keep the sample at the same temperature as the reference 5. In the DSC diagram, a peak is then observed, the so-called melting peak.

Following the heating run (H), a cooling run (K) is usually measured. The sample and the reference are cooled linearly, so it is heat from the

10 sample and the reference dissipated. During the crystallization or solidification of the sample (liquid-solid phase transformation), a larger amount of heat Q has to be dissipated in order to keep the sample at the same temperature as the reference, since heat is released during crystallization or solidification. In the DSC diagram of the cooling run (K) then a peak, the so-called crystallization peak, in

15 opposite direction to the Aufschmelzpeak observed.

In the context of the present invention, the heating during the heating run usually takes place at a heating rate of 20 K / min. The cooling during the cooling is usually carried out in the context of the present invention with a cooling rate of 20 20 K / min.

A DSC diagram with a heating run (H) and a cooling run (K) is shown by way of example in FIG. On the basis of the DSC diagram, the onset temperature of the melting (T _M ^onset ) and the onset temperature of the crystallization (T _c ^onset ) can be determined 25.

To determine the onset temperature of the reflow (T _M ^onset ), a tangent is applied to the baseline of the heating run (H), which runs at the temperatures below the melting peak. A second tangent is applied to the first inflection point of the reflow peak, which at temperatures below the temperature is at the maximum of the reflow peak. The two tangents are extrapolated to intersect. The vertical extrapolation of the point of intersection to the temperature axis indicates the onset temperature of the melting (T _M ^onset ).

35

To determine the onset temperature of the crystallization (T _c ^onset ), a tangent is applied to the baseline of the cooling run (K), which runs at the temperatures above the crystallization peak. A second tangent is applied to the inflection point of the crystallization peak, which at temperatures above the temperature is at the 40 minimum of the crystallization peak. The two tangents are extrapolated to intersect. The vertical extrapolation of the point of intersection to the temperature axis indicates the onset temperature of the crystallization (T _c ^onset ). The sintering window (W) results from the difference between the onset temperature of the melting (T _M ^onset ) and the onset temperature of the crystallization (T _c ^onset ).

W = T _M ^onset - T _c ^onset .

In the context of the present invention, the terms "sintering window (W _S p)", "size of the sintering window (W _S P)" and "difference between the onset temperature of the melting (T _M ^onset ) and the onset temperature of the crystallization ( T _c ^onset ) "have the same meaning and are used synonymously.

The sintering powder (SP) according to the invention is particularly suitable for use in a sintering process.

The present invention therefore also relates to the use of a sintered powder (SP) containing the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

(C) contains at least one near-infrared reflector, in a sintering process. moldings

By the method according to the invention a shaped body is obtained. The shaped body can be removed from the powder bed directly after the solidification of the sintering powder (SP) melted during the exposure in step ii). It is also possible to cool the shaped body first and then remove it from the powder bed. Optionally adhering particles of the sintering powder that have not been melted can be mechanically removed from the surface by known methods. Methods of surface treatment of the molded article include, for example, tumbling or sliding cutting, and sandblasting, glass bead blasting or microblasting.

It is also possible to further process the resulting shaped articles or, for example, to treat the surface. A further subject of the present invention is therefore a shaped body obtainable by the process according to the invention. The resulting molded articles usually contain in the range from 50 to 94.95% by weight of component (A), in the range from 5 to 40% by weight of component (B) and in the range from 0.05 to 10% by weight. % of component (C), in each case based on the total weight of the molding.

The shaped body preferably contains in the range from 60 to 94.9% by weight of component (A), in the range from 5 to 30% by weight of component (B) and in the range from 0.1 to 8% by weight. the component (C), in each case based on the total weight of the molding.

Most preferably, the molded body contains in the range of 70 to 91, 9 wt .-% of component (A), in the range of 8 to 25 wt .-% of component (B) and in the range of 0.1 to 5 wt. -% of component (C), in each case based on the total weight of the molding.

In the present invention, the component (A) is the component (A) contained in the sintered powder (SP). Also, the component (B) is the component (B) contained in the sintering powder (SP) and the component (C) is the component (C) contained in the sintering powder (SP).

If the sintering powder (SP) contains the at least one additive and / or the at least one reinforcing agent, the shaped body obtained according to the invention usually also contains the at least one additive and / or the at least one reinforcing agent.

When step i-1) has been performed, the molded article may further contain the IR absorbing ink.

It is clear to the person skilled in the art that the exposure of the sintering powder (SP) allows the components (A), (B) and (C) and optionally the at least one additive and the at least one reinforcing agent to undergo chemical reactions and thus to change. Such reactions are known in the art.

The components (A), (B) and (C) and, if appropriate, the at least one additive and the at least one reinforcing agent do not undergo a chemical reaction during the exposure in step ii), but the sintered powder (SP) merely melts.

By using the near-infrared reflector (component (C)) in the sintered powder, warpage in the production of molded articles from the sintered powder (SP) by exposing the sintered powder (SP) is reduced. The present invention therefore also relates to the use of a near-infrared reflector in a sintered powder (SP) comprising the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

(C) contains at least one near-infrared reflector, for reducing the delay in the production of moldings from the sintered powder (SP) by exposing the sintering powder (SP).

The invention will be explained in more detail below by means of examples, without limiting it thereto.

Examples

The following components are used.

Semi-crystalline polyamide (component (A)):

(P1) Polyamide 6/66 (Ultramid C33, BASF SE)

amorphous polyamide (component (B)):

(AP1) Polyamide 6I / 6T (Grivory G16, Ems) with a molar ratio of 6I: 6T of 1.9: 1

- Near-infrared reflector (component (C)):

(C1) titanium dioxide (Kronos 2220, Kronos)

(C2) iron chromium oxide (Sicopal Black K0095, BASF SE)

(C3) titanium dioxide (Kronos 2222, Kronos company)

(C4) Perylene Pigment (Lumogen Black FK 4281, BASF SE)

(C5) perylene pigment (Lumogen Black K 0087, BASF SE)

(C6) perylene pigment (Paliogen Black S 0084, BASF SE)

(C7) aluminum pigment (IReflex 5000 White, Eckart)

Reinforcing agent:

(VS1) kaolin (Translink 445, BASF SE) Additive: phenolic antioxidant (Irganox 1098 (N, N'-hexane-1,6-diylbis (3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide))), BASF SE)

Special black 4 (carbon black CAS No. 1333-86-4, Evonik)

Alu C (Rieselhilfe, Evonik) with a BET surface area of 100 ± 15 m ² / g and a pH of 4.5 to 5.5

Irgaphos 168 (phosphitic antioxidant, BASF)

Table 1 shows the essential parameters of the semicrystalline polyamides used (component (A)), in Table 2 the essential parameters of the amorphous polyamides used (component (B)).

Table 1

AEG indicates the amino end group concentration. This is determined by means of titration. To determine the amino end group concentration (AEG), 1 g of the component (semicrystalline polyamide or amorphous polyamide) is dissolved in 30 ml of a phenol / methanol mixture (phenol to methanol 75:25 by volume) and then titrated visually with 0.2 N hydrochloric acid in water ,

CEG indicates the carboxyl end group concentration. This is determined by means of titration. To determine the carboxyl end group concentration (CEG), 1 g of the component (semicrystalline polyamide or amorphous polyamide) is dissolved in 30 ml of benzyl alcohol and then titrated visually at 120 ° C. with 0.05 N potassium hydroxide in water.

The melting temperature (T _M ) of the partially crystalline polyamides and all glass transition temperatures (T _G ) were determined in each case by means of differential scanning calorimetry. To determine the melting temperature (T _M ), as described above, a first heating run (H 1) was measured at a heating rate of 20 K / min. The melting temperature (T _M ) then corresponded to the temperature at the maximum of the melting peak of the first heating run (H 1).

To determine the glass transition temperature (T _G ), a cooling run (K) and subsequently a second heating run (H2) were measured after the first heating run (H 1). The cooling was measured at a cooling rate of 20 K / min. The first heating (H 1) and the second heating (H2) were measured at a heating rate of 20 K / min. The glass transition temperature (T _G ) was then determined halfway up the stage of the second heating run (H2).

The zero shear rate viscosity η ₀ was determined using a TA Instruments "DHR-1" rotational viscometer and a 25 mm diameter plate-and-plate geometry with a gap spacing of 1 mm Days were dried under vacuum at 80 ° C. and then measured with a time-dependent frequency sweep (sequence test) with an angular frequency range of 500 to 0.5 rad / s The following further measuring parameters were used: deformation: 1.0%, measuring temperature: 240 ° C. , Measuring time: 20 min, preheating time after sample preparation: 1, 5 min.

Production of Sintered Powders in a Twin-Screw Extruder For the production of sintered powders, the components indicated in Table 3 were in the ratio shown in Table 3 in a twin-screw extruder (ZE25) with a throughput of 20 kg / h, a speed of 230 rpm, a length To a diameter ratio of 40 and a housing temperature of 245 ° C, compounded and then processed with a liquid nitrogen cooled pin mill to powders (particle size distribution 10 to 100 μηη).

Table 3

In (P1) (AP1) (A1) (VS1) (A2) (C1) (C2) (A3) (wt%) [wt%] [wt%] [wt%] [Wt%] [wt%] [wt%] [wt%]

V1 55.98 8.77 0.25 35 - - - 0.4

V2 55.68 8.77 0.25 35 0.3 - - 0.4

B3 55.55 8.7 0.25 35 - 0.5 - 0.4

B4 55.48 8.77 0.25 35 - - 0.5 0.4

B5 85.38 13.37 0.25 - - 1 - 0.4 For the powders, the melting temperature (T _M ) was determined as described above. The crystallization temperature (T _c ) was determined by Differential Scanning Calorimetry (DSC). For this purpose, first a heating run (H) with a heating rate of 20 K / min and then a cooling run (K) with a cooling rate of 20 K / min were measured. The crystallization temperature (T _c ) is the temperature at the extremum of the crystallization peak.

The amount of complex shear viscosity was determined by a plate-plate rotary rheometer at an angular frequency of 0.5 rad / s and a temperature of 240 ° C. A rotary viscometer "DHR-1" from TA Instruments was used, the diameter being 25 mm and the gap spacing being 1 mm, and unannealed samples were dried for 7 days at 80 ° C. under vacuum and then subjected to a time-dependent frequency sweep (sequence test). measured with a circular frequency range of 500 to 0.5 rad / s The following further measuring parameters were used: deformation: 1, 0%, measuring 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 the melting (T _M ^onset ) and the onset temperature of the crystallization (T _c ^onset ). To determine the thermooxidative stability of the sintering powder, the complex shear viscosity of freshly prepared sintering powders and of sintering powders after furnace storage at 0.5% oxygen was determined for 16 hours and 195 ° C. The ratio of the viscosity after storage (after aging) to the viscosity before storage (before aging) was determined. The viscosity is measured by means of rotational rheology at a measuring frequency of 0.5 rad / s at a temperature of 240 ° C.

The particle size distribution, reported as D10, D50 and D90, was determined as described above using a Malvern Mastersizer. The incineration residue was determined gravimetrically after incineration.

The results are shown in Table 4. Table 4

* nb: not determined

For the sintering powder (SP) also their reflection in the wavelength range of the near infrared was determined. The determination was carried out with a PerkinElmer UV / VIS / NI R spectrophotometer Lambda 950 with 150 mm integrating sphere, reference: Spektraion white standard from Labsphere; Cuvette: special fiber cuvette made of quartz glass (d = 0.5 cm); Data interval: 1, 0 nm; Gap width: UV / VIS (200-800 nm) = 2.0 nm, NI R (810-2,100 nm): servo; Integration time: UV / VIS: 0.2 s, NI R: 0.2s; Gain: UV / VIS: auto, NI R: 15; Measuring speed: UV / VIS / NI R: 285 nm / min ,, wavelength range: 300 - 2500 nm; Gloss trap: closed.

The results are shown in Table 5. Table 5

Example middle middle middle middle

Reflection, Reflection, Reflection, Reflection, WavelengthsWavelengthsWavelength range range 400 - 800 nm 200 - 2500 nm 800 - 2500 nm 1200 - 2500 nm

[%] [%] [%] [%]

V1 63.8 52.3 53.2 50.0

V2 12.5 15.3 16.3 17.0

B3 60.4 48.9 49.8 47.0

B4 34.0 43.4 48.6 47.3

B5 81, 5 62.7 60.8 54.0 It can be clearly seen that the sintering powders (SP) according to the invention have a good reflection of the radiation in the near infrared range.

In addition, it is possible with the sintering powder (SP) according to the invention to produce black-colored shaped bodies, the sintering powders simultaneously having a high reflection in the NI R range.

Laser sintering tests The sintered powders (SP) were introduced into the space at the temperature indicated in Table 6 with a layer thickness of 0.1 mm. Subsequently, the sintering powders were exposed with a laser, with the laser power indicated in Table 6 and the specified point distance, the speed of the laser over the sample during the exposure being 15 m / sec. The dot pitch is also referred to as laser spacing or track pitch. In selective laser sintering, scanning is usually done in stripes. The dot spacing indicates the distance between the centers of the stripes, ie between the two centers of the laser beam of two stripes.

Table 6

Subsequently, the properties of the obtained tensile bars (sintered bars) were determined. The test of the resulting tensile bars (sintered rods) was carried out in a dry state after drying at 80 ° C for 336 hours in vacuo. The results are shown in Table 7.

Charpy rods were also prepared, which were also tested dry (according to ISO 179-2 / 1 eU: 1997 + Amd. 1: 201 1 and according to ISO 179-2 / 1 eA (F): 1997 + Amd. 1: 201 1) The tensile tests were carried out in accordance with ISO 527-2: 2012.

The heat deflection temperature (HDT) was determined according to ISO 75-2: 2013, using both method A with a Randfaserspannung of 1, 8 N / mm ² , and Method B was used with a marginal fiber tension of 0.45 N / mm ² .

Table 7

Table 8 shows the properties of the shaped bodies in the conditioned state. For conditioning, the moldings were stored after the drying described above for 336 hours at 70 ° C and 62% relative humidity. Table 8

Production of powders in a mini extruder

For the near infrared reflectors as well as for the component (A2) (special black 4), the reflection in the near infrared wavelength range was determined as described above.

The results are shown in Table 9. Table 9

Subsequently, to prepare powders, the components shown in Table 10 were in the ratio shown in Table 10 in a DSM 15 cm ³ -inline extruder (DSM-Micro15 microcompounder) at a speed of 80 rpm (revolutions per minute) at 250 ° C compounded for a mixing time of 3 min (minutes) and then milled to a particle size of <200 μηη. Table 10

For the resulting sintered powder (SP), the reflection in the wavelength range of the near infrared was then determined. The determination was made as described above. The results are shown in Table 1 1.

n. b. *: not determined

It can be clearly seen that an increased reflection, in particular in the wavelength range from 800 to 2500 nm (800 nm to 2.5 μm), is achieved by the near-infrared reflectors according to the invention in sintered powders (SP) compared to sintered powders without near-infrared reflector (Comparative Example C6).

High Speed Sintering HSS (Multi-Jet Fusion, HP) trials:

To prepare the sintering powders for high-speed sintering, the components indicated in Table 12 were compounded in the ratios shown there as described above before Table 3 and then ground. Table 12: Formulations for high-speed sintering tests

Table 13: Analytical data of the powders for HSS experiments

Table 14: Experimental parameters of the HSS experiments

Powder V2 can not be processed into components by HSS, as there is no significant difference in temperature between the surface of the component to be sintered and the surface of the surrounding powder. Powder B18 can be very well processed despite blackening with a significant temperature difference. Table 15: Mechanical properties of the rapid test specimens according to HSS

To attempt

The mechanical properties of the moldings obtained in the HSS tests were determined on rapid test specimens (type 2 according to ISO 8256 or according to ISO 527-2: 2012 type CW, test speed 1 mm / min at 23 ° C. and 50% relative humidity Dry specimens after 336 hours in vacuo at 80 ° C).

Claims

claims

1 . A method of producing a shaped article comprising the steps of: i) providing a layer of a sintering powder (SP) comprising the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

2. The method according to claim 1, characterized in that the component (C) radiation having a wavelength in the range of 780 nm to 2.5 μηη to at least 60% reflected.

3. The method according to claim 1 or 2, characterized in that the component (C) is selected from the group consisting of near-infrared-reflecting pigments.

4. The method according to any one of claims 1 to 3, characterized in that the exposure in step ii) is carried out with a radiation source which is selected from the group consisting of lasers and infrared radiators.

5. The method according to any one of claims 1 to 4, characterized in that the sintering powder (SP) in the range of 50 to 94.95 wt .-% of component (A), in the range of 5 to 40 wt .-% of the component (B) and in the range of 0.05 to 10 wt .-% of component (C), in each case based on the total weight of the sintering powder (SP).

6. The method according to any one of claims 1 to 5, characterized in that the component (A) is selected from the group consisting of PA 4, PA 6,

PA 7, PA 8, PA 9, PA 1 1, PA 12, PA 46, PA 66, PA 69, PA 6.10, PA 6.12, PA 6.13, PA 6 / 6.36, PA 12.12, PA 13.13, PA 6T, PA6T / 6, PA MXD6, PA 6/66, PA 6/12 and copolyamides of these.

7. The method according to any one of claims 1 to 6, characterized in that the component (B) is selected from the group consisting of PA 6I / 6T, PA 61 and PA 6 / 3T.

8. The method according to any one of claims 1 to 7, characterized in that between step i) and step ii) a step i-1) applying at least one I R-absorbing ink on at least a portion of the provided in step i) layer of the sintering powder (SP) is performed.

9. The method according to any one of claims 1 to 8, characterized in that the sintering powder (SP) additionally in the range of 0, 1 to 10 wt .-% of at least one additive selected from the group consisting of

Containing antinucleating agents, stabilizers and end group functionalizing, based on the total weight of the sintering powder (SP).

10. The method according to any one of claims 1 to 9, characterized in that in the sintering powder (SP), the component (C) with the component (A) and / or with the component (B) is coated.

1 1. Process for producing a sintered powder (SP) comprising the steps of a) mixing the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

12. sintering powder (SP) obtainable by a process according to claim 1 1.

13. Using a near-infrared reflector in a sintered powder (SP) containing the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

(C) at least one near-infrared reflector contains, for reducing the delay in the production of moldings from the sintered powder (SP) by exposing the sintering powder (SP).

14. Use of a sintering powder (SP) containing the components

(A) at least one partially crystalline polyamide,

(B) at least one amorphous polyamide,

(C) contains at least one near-infrared reflector, in a sintering process.

15. Shaped article obtainable by a process according to one of claims 1 to 10.