Polymer powder for producing three-dimensional objects
View Patent ↗The invention relates to the use of a powder made of a polymer, which of two or more components with functionalities suitable for Diels-Alder reactions, or of a powder mixture (dry blend) made of powders respectively of at least one of the reactive components, where these together enter into the Diels-Alder reaction with one another and are capable of a retro-Diels-Alder reaction, in a rapid-prototyping process. The invention further relates to moldings produced with use of said polymer powder through a layer-by-layer shaping process in which regions of a powder layer are melted selectively. The molding here can be removed from the powder bed after cooling and hardening of the regions previously melted layer-by-layer.
1. A process for laser-sintering a crosslinked powder material, the process comprising:
crosslinking a powder material by a Diels-Alder reaction or a hetero-Diels-Alder reaction at a temperature 1, said temperature 1 being from 0 to 80° C.;
providing a crosslinked powder material in form of a powder bed; and
selectively reversing the crosslinking of the powder material to an extent of at least 50% by heating the powder material at a temperature 2 said temperature 2 being higher than the temperature 1,
wherein the powder material comprises a component A having at least two dienophilic double bonds and a component B at least two diene functionalities, and
at least one of the components A and B has more than two of corresponding functionalities.
2. The process as claimed in claim 1 , wherein the temperature 1 is room temperature, and the powder material is flowable after heating the powder material to temperature 2.
3. The process as claimed in claim 2 , the process further comprising:
after heating the powder material to temperature 2, cooling the powder material in turn, thereby solidifying the powder material to obtain a molding.
4. The process as claimed in claim 1 ,
wherein at least one of the components A, B or both is a polymer.
5. The process as claimed in claim 4 ,
wherein the component A and the component B are polymers where the polymers thereof are identical or different.
6. The process as claimed in claim 5 ,
wherein the powder material is a mixture of at least two different powders, and
at least one powder is the component A and at least one other powder is the component B.
7. The process as claimed in claim 4 ,
of the components A, B, or both is at least one polymer selected from the group consisting of a polyacrylate, a polymethacrylate, a polystyrene, a copolymer of an acrylate, methacrylate, styrene, or any combination thereof, a polyacrylonitrile, a polyether, a polyester, a polylactic acid, a polyamide, a polyesteramide, a polyurethane, a polycarbonate, an amorphous or semicrystalline poly-αolefin, an EPDM, an EPM, a hydrogenated or non-hydrogenated polybutadiene, an ABS, an SBR, a polysiloxane, and a block, comb, star, or any combination copolymer thereof.
8. The process as claimed in claim 1 ,
wherein the components A and B make up at least 50% by weight of the powder material.
9. The process as claimed in claim 1 ,
wherein the powder material comprises at least 50% by weight of an inorganic component.
10. The process as claimed in claim 1 , wherein
said heating the powder material at a temperature 2 is carried out with electromagnetic radiation.
11. The process as claimed in claim 10 , wherein said electromagnetic radiation is in the form of laser radiation.
12. The process as claimed in claim 3 , further comprising:
processing the molding in turn via grinding to obtain the powder material, and
optionally recycling the powder material in turn in the process for laser-sintering the crosslinked powder material.
13. The process as claimed in claim 1 , further comprising:
controlling a temperature of the powder bed during the process to a temperature 3 which is between the temperature 1 and the temperature 2.
14. The process as claimed in claim 1 ,
wherein the component A is a compound with a carbon-sulfur double bond.
15. The process as claimed in claim 14 ,
wherein the component A is a compound of formula:
wherein Z is an electron-withdrawing group,
R m is a polyvalent organic group or a polymer, and
n is a number from 2 to 20.
16. A molding comprising a crosslinked material,
wherein the molding is obtained by the process according to claim 1 .