ADDITIVE MANUFACTURING PROCESS USING AMINES FOR THE POST-HARDENING

Abstract

The invention relates to a method for producing an object, comprising the step of producing the object from a construction material by means of an additive manufacturing process, wherein the construction material comprising a polyurethane and/or polyester polyol. The construction material further comprises a polyamine component and during and/or after the production of the object, the construction material is heated to a temperature of 50 C. The invention also relates to an object obtained according to the claimed method.

Claims

1. A method of producing an article, comprising: producing the article in an additive manufacturing method from a build material, wherein the build material comprises a polyurethane polymer, a polyester polymer, or a combination thereof, wherein the build material further comprises a polyamine component and wherein the build material is heated to a temperature of 50 C. during the production of the article, after the production of the article, or both.

2. The method as claimed in claim 1, wherein the build material is free-radically crosslinkable and comprises groups having Zerewitinoff-active hydrogen atoms, and wherein the method further comprises: I) depositing free-radically crosslinked build material on a carrier so as to obtain a first layer of build material bonded to the carrier and corresponding to a first selected cross section of the precursor; II) depositing free-radically crosslinked build material onto the first layer or another previously applied layer of build material so as to obtain another layer of build material corresponding to another selected cross section of the precursor and bonded to the first layer or the previously applied layer; III) repeating step II) until a precursor is formed; wherein the depositing of free-radically crosslinked build material at least in step II) comprises exposure and/or irradiation of a selected region of free-radically crosslinkable build material corresponding to the respectively selected cross section of the precursor and wherein the free-radically crosslinkable build material has a viscosity of 5 mPas to 100 000 mPas at 23 C. based on DIN EN ISO 2884-1, wherein the free-radically crosslinkable build material comprises a curable component including ester groups, urethane groups, or a combination thereof and olefinic CC double bonds and wherein step III) is followed by a further step IV): IV) heating the precursor obtained after step III) to a temperature of 50 C. to obtain the article.

3. The method as claimed in claim 2, wherein: the carrier is arranged within a container that is vertically lowerable in the direction of gravity, the container contains the free-radically crosslinkable build material in an amount sufficient to cover at least the carrier, an uppermost surface of crosslinked build material deposited on the carrier, or a combination thereof as viewed in a vertical direction, before each step II) the carrier is lowered by a predetermined distance so that a layer of the free-radically crosslinkable build material is formed above an uppermost layer of the crosslinked build material as viewed in the vertical direction and in step II) an energy beam exposes, irradiates, or a combination thereof the selected region of the layer of the free-radically crosslinkable build material corresponding to the respectively selected cross section of the precursor.

4. The method as claimed in claim 2, wherein: the carrier is arranged within a container that is vertically raisable counter to the direction of gravity, the container provides the free-radically crosslinkable build material, before each step II) the carrier is raised by a predetermined distance so that a layer of the free-radically crosslinkable build material is formed below a lowermost layer of the crosslinked build material as viewed in a vertical direction and in step II) a multitude of energy beams simultaneously exposes, irradiates, or a combination thereof the selected region of the layer of the free-radically crosslinkable build material corresponding to the respectively selected cross section of the precursor.

5. The method as claimed in claim 2, wherein: in step II) the free-radically crosslinkable build material is applied from one or more print heads corresponding to the respectively selected cross section of the precursor and then exposed, irradiated, or a combination thereof.

6. The method as claimed in claim 1, wherein the polyamine component has an average number of Zerewitinoff-active hydrogen atoms of 2.

7. The method as claimed in claim 1, wherein the polyamine component comprises one or more of: adipic dihydrazide, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine, hexamethylenediamine, hydrazine, isophoronediamine, (4,4- and/or 2,4-)diaminodicyclohexylmethane, (4,4- and/or 2,4-)diamino-3,3-dimethyldicyclohexylmethane and N-(2-aminoethyl)-2-aminoethanol.

8. The method as claimed in claim 1, wherein the polyamine component is present in a proportion of 0.1% by weight to 20% by weight, based on the weight of the build material.

9. The method as claimed in claim 1, wherein the polyurethane polymer in the build material has an average molecular weight of linear repeat units M.sub.u of 100 g/mol to 2000 g/mol, where M.sub.u is calculated as follows:
M.sub.u=((M.sub.i/R.sub.i)+(M.sub.p/R.sub.p))*200 with: M.sub.i molecular weight of an NCO group M.sub.p molecular weight of an OH group R.sub.i average NCO group content in % by weight based on a total weight of polyisocyanates used in the build material for preparation of the polyurethane polymer, based on ISO 11909 R.sub.p average OH group content in % by weight based on a total weight of polyols used in the build material for preparation of the polyurethane polymer, based on DIN 53240.

10. The method as claimed in claim 1, wherein the polyester polymer in the build material has an average molecular weight of linear repeat units M.sub.u of 100 g/mol to 1000 g/mol, where M.sub.u is calculated as follows:
M.sub.u=((M.sub.i/R.sub.i)+(M.sub.p/R.sub.p))*200 with: M.sub.i molecular weight of an acid group M.sub.p molecular weight of an OH group R.sub.i average acyl group content in % by weight based on a total weight of polycarboxylic acid used in the build material for preparation of the polyester polymer or their equivalents, based on a titration of the average acid group content in water versus KOH of the polycarboxylic acids R.sub.p average OH group content in % by weight based on a total weight of polyols used in the build material for preparation of the polyester polymer, based on DIN 53240.

11. An article obtainable by the method as claimed in claim 1.

12. The article as claimed in claim 11, wherein the build material has a urea group content of 0.1% by weight to 15% by weight, an amide group content of 0.1% by weight to 10% by weight, or both.

13. The article as claimed in claim 11, wherein the build material has a melting point of 60 C. based on DSC.

14. The article as claimed in claim 11, wherein the build material has a different melting point than the build material present before commencement of the method of claim 1.

15. The article as claimed in claim 11, wherein the build material has a different modulus of elasticity than the build material present before commencement of the method of the claim 1 based on ISO 527.

Description

EXAMPLES

[0130]

TABLE-US-00003 Example 1 2* 3* 4* Feedstocks Weight [g] Polyisocyanate 33.8 33.8 33.8 33.8 HEMA 26.2 26.2 26.2 26.2 IBOMA 40 40 40 40 IPDA 2.98 HDA 2.03 Jeffamine 403 5.14 Omnirad 1173 3 3 3 3 UV curing + oven curing Assessment of film solid solid solid solid film film film film HM (Martens hardness 172 146 168 142 (N/mm.sup.2)) nIT (elastic deformation 59 67 66 62.9 component %) Tg first heating [ C.] 55/127 54/116 54/118 77/119 IR, NH.sub.2 (wagging) signal at 810 cm.sup.1

[0131] Comparative experiment 1 was conducted without use of an amine and showed the greatest hardness at 172 N/mm.sup.2. The use of an amine crosslinker in inventive experiments 2 to 4 showed a reduced hardness value and elasticization. This can be explained chemically by the incorporation of the amines into the polymer. In accordance with the functionality and equivalent weights of the amines, moreover, the Tg and the mechanical properties of the product mixture were altered, which can be explained by the formation of urea/amide bonds from existing ester and urethane bonds. The network density can increase or decrease according to the incorporation point.

TABLE-US-00004 Example 5 6 7 8 Feedstock Weight [g] Desmodur N 5.6 5.6 5.6 5.6 3600 HEMA 4.4 4.4 4.4 4.4 IBOMA 50 50 50 50 HDDMA 40 40 40 40 IPDA 2.98 HDA 2.03 Jeffamine 403 5.14 Omnirad 1173 3 3 3 3 UV curing and storage at RT for 24 h Assessment of solid film amine amine amine film incompletely incompletely incompletely reacted, reacted, reacted, tacky film tacky film tacky film IR, NH.sub.2 visible visible visible (wagging) signal at 810 cm.sup.1

[0132] Further comparative experiments were conducted with mixtures having a urethane density of <5% and storage at room temperature for 24 hours. In the case of comparative film 5 without amine, a solid film was found. In the case of comparative experiments 6, 7 and 8 with variation of the amines, the amine was incompletely incorporated into the film. Unconverted amine was clearly detectable both by the odor and in the infrared spectrum (IR) from the NH vibrations (also called NH wagging or NH.sub.2 wagging), and was manifested in a tacky film consistency.