US-12624223-B2 - Polymer powder for 3D printing

US12624223B2US 12624223 B2US12624223 B2US 12624223B2US-12624223-B2

Abstract

The invention is targeted mainly at a polymer powder suitable for 3D printing by sintering, comprising: (a) a polymer composition comprising at least one thermoplastic elastomer; (b) a pigment composition comprising at least one pigment exhibiting an absorbance of the light with a wavelength of 1000 nm, as measured according to the standard ASTM E1790, of less than 50%; and also, if appropriate, (c) one or more fillers or reinforcements; and (d) one or more additional additives. The invention is also targeted at a process for the preparation of said powder and also at the use of said powder for 3D printing by sintering. Finally, it is targeted at the use of a pigment exhibiting an absorbance of the light with a wavelength of 1000 nm, as measured according to the standard ASTM E1790, of less than 50% to improve the definition and/or the mechanical properties of the articles printed by a process of 3D printing by sintering of a thermoplastic elastomer powder.

Inventors

Alexis MORFIN

Assignees

ARKEMA FRANCE

Dates

Publication Date: 20260512
Application Date: 20220114
Priority Date: 20210114

Claims (9)

1 . A polymer powder suitable for three-dimensional (3D) printing by sintering, comprising: (a) a polymer composition comprising at least one thermoplastic elastomer; (b) a pigment composition comprising at least one pigment exhibiting an absorbance of the light with wavelengths of the spectrum from 750 to 1250 nm, as measured according to the standard ASTM E1790, of less than 35%; (c) optionally, one or more fillers or reinforcements; and (d) optionally, one or more additional additives, wherein the pigment has a volume-median diameter Dv50 less than that of the polymer powder, wherein the polymer powder comprises from 0.3% by weight to 2% by weight of the pigment composition.
2 . The powder as claimed in claim 1 , wherein the polymer powder exhibits a Dv50 diameter, as measured according to the standard ISO 9276-Parts 1 to 6, of 40 to 150 μm.
3 . The powder as claimed in claim 1 , wherein the thermoplastic elastomer is selected from the group consisting of a copolymer having polystyrene and polybutadiene blocks (SBS), a copolymer having polystyrene and polyisoprene blocks (SIS), a copolymer having polystyrene and poly(ethylene/butylene) blocks (SEBS), a copolymer having isocyanate and ether or ester blocks (TPU), a copolymer having polyester and polyester or polyether blocks (COPE), a copolymer having polyamide and polyether blocks (PEBA), and mixtures and alloys thereof.
4 . The powder as claimed in claim 3 , wherein the thermoplastic elastomer is selected from PEBA.
5 . The powder as claimed in claim 1 , wherein the thermoplastic elastomer is selected from the group consisting of thermoplastic polyolefin (TPO), a copolymer of butadiene and acrylonitrile, vulcanized or not, dispersed in a polypropylene (PP/NBR), a chlorinated polyethylene dispersed in a polyolefin (PO/CPE-VD), an ethylene vinylidene acetate dispersed in vinylidene chloride (EVA/VC), a copolymer of butadiene and acrylonitrile, vulcanized or not, dispersed in a polyvinyl chloride (PVC/NBR), and mixtures thereof.
6 . The powder as claimed in claim 1 , wherein the pigment is at least one compound selected form the group consisting of metal oxides, transition metal oxides, and mixtures thereof, mixed oxides, and doped oxides.
7 . The powder as claimed in claim 6 , wherein the pigment is at least one oxide selected from the group consisting of tin, magnesium, copper, zinc, iron, manganese, cobalt, nickel, aluminum, antimony, chromium, titanium, or silicon oxides, and mixtures thereof, mixed oxides, and doped oxides.
8 . A three-dimensional (3D) printing process comprising sintering the polymer powder as claimed in claim 1 .
9 . An article obtained by three-dimensional (3D) printing by sintering of the polymer powder as defined in claim 1 .

Description

TECHNICAL FIELD The present patent application relates to a thermoplastic elastomer powder of use for 3D printing by sintering, to a process for its manufacture, and also to its use for 3D printing by sintering. It furthermore relates to the use of specific pigments to improve the definition and/or the mechanical properties of articles printed from thermoplastic elastomer by 3D printing by sintering. PRIOR ART 3D printing, or additive manufacturing, denotes various techniques for the manufacture of articles by addition of material and not by subtraction, and is currently experiencing remarkable growth. Among the 3D printing processes available today, some use a bed of polymer powder to build the article, layer by layer, by localized sintering of grains of powder, for example by means of a laser (technique called “selective laser sintering” or SLS) or of the targeted application of a binding agent and of a “detailing agent” and subsequent heating (technique called “Multi-jet fusion” or MJF). In most machines for 3D printing by sintering, the powder, preheated in a reservoir tank close to the the construction chamber, is introduced into the construction chamber, spread in a thin layer and then heated, for example from above by infrared (IR) radiation lamps, before being selectively melted by an electromagnetic energy source. The homogeneity of the temperature in the powder bed constitutes a particular challenge. This is because the powder is heated to a temperature situated in the interval between the crystallization temperature Tc and the melting temperature Tf of the polymer. This interval depends on the polymer used but is often quite small, of the order of 30° C. The processability window, defined as the range of temperatures at which the powder can give good quality parts, is even more restricted, and is most often less than 10° C., indeed even 5° C. Control of the temperature in the powder bed before its selective melting is thus very important. However, the homogeneous illumination of the entire bed is technically difficult, due to the modularity of the lamps used for this purpose. Moreover, the IR radiation does not heat the air but the surface of the solid which it strikes. This results in a variation in temperature in the powder bed and between the air in the construction chamber and the surface of the powder bed which can reach several degrees. However, a nonhomogeneous temperature in the powder can cause various problems. When the temperature of the powder is too high, the powder tends to agglomerate, a phenomenon which is called “caking”, and which prevents the powder from correctly spreading. Furthermore, the subsequent selective melting of a powder which is too hot can result in sintering of the neighboring grains as well, and harm the good definition of the articles. When, conversely, the temperature of the powder is too low, the grains can be incompletely sintered. This has the effect of damaging the mechanical properties of the printed article. Finally, a temperature difference, for example between the air of the chamber and the surface of the powder, can create stresses in the part, which cause its deformation. This phenomenon, called “curling”, often prevents the printing from being continued and thus has, as consequence, significant losses. The variations in temperature in the bed of polymer powder can thus have harmful consequences in terms of quality of the printed article, indeed even can compromise its production. Thermoplastic elastomers are particularly advantageous since they combine, in one and the same polymer, mechanical properties having very good resistance to thermal aging or aging under UV, and also a low density, and thus make possible the preparation of light and flexible articles. The variations in temperature in the powder are, however, particularly troublesome for these polymers because of their expanded melting temperature, especially when the enthalpy of fusion is low. Due to the problems discussed above, the articles obtained by 3D printing by sintering of powder of thermoplastic elastomers can be problematic to implement and the articles manufactured do not always exhibit the desired appearance and/or properties. There thus exists a need to provide a solution to the abovementioned problems, in particular to be able to manufacture, with a thermoplastic elastomer powder, by 3D printing by sintering, articles of good quality, having good mechanical properties and precise and well-defined dimensions and contours. There is also a need to provide a solution for widening the working window of these polymers, and thus implementing the printing process more easily and/or with more polymers. SUMMARY OF THE INVENTION It is an aim of the invention to provide a solution to one or more of the abovementioned problems. This is because the present invention is based on the unexpected observation that the addition, to the thermoplastic elastomer powder, of pigments having low absorba