POLYMERS AS SUPPORT MATERIAL FOR USE IN FUSED FILAMENT FABRICATION

Abstract

The present invention relates to the use of a polymer comprising polymerized units (A) and (B): (A) at least one first monomer of the formula (I) where n is 3 to 12; m is 0 to 3; R.sup.1 is C.sub.1-C.sub.10-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl; R.sup.2, R.sup.3 and R.sup.4 are each, independently of one another, hydrogen, C.sub.1-C.sub.10-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl; and (B) at least one second monomer of the formula (II) where R.sup.5, R.sup.6 and R.sup.7 are each, independently of one another, hydrogen, C.sub.1-C.sub.10-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl; R.sup.8 is C.sub.1-C.sub.20-alkyl, C.sub.2-C.sub.10alkenyl, aryl or aralkyl; as a support material in a fused filament fabrication process.

##STR00001##

Claims

1-14. (canceled)

15. A process fbr producing a three-dimensional object, the process comprising the steps: i) depositing a support material into a build chamber with a layer-based additive technique to form a support structure; ii) depositing a modeling material into the build chamber with the layer-based additive technique to form the three-dimensional object, wherein the three-dimensional object comprises at least one region supported by the support structure; and iii) removing the support structure from the three-dimensional object with an aqueous solution, wherein the support material comprises a polymer comprising polymerized units (A) and (B): (A) at least one first monomer of formula (I): ##STR00013## where n is 3 to 12; m is 0 to 3; R.sup.1 is C.sub.1-C.sub.10-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl; R.sup.2, R.sup.3 and R.sup.4 are each, independently of one another, hydrogen, C.sub.1-C.sub.10-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl; and (B) at least one second monomer of formula (II) ##STR00014## where R.sup.5, R.sup.6 and R.sup.7 are each, independently of one another, hydrogen, C.sub.1-C.sub.10-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl; R.sup.8 is C.sub.1-C.sub.20-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl.

16. The process according to claim 15, wherein the polymer comprises at least 20% by weight of polymerized Unit (A), based on the total weight of the polymer.

17. The process according to claim 15, wherein the polymer comprises 20 to 80% by weight of polymerized unit (A) and 80 to 20% by weight of polymerized unit (B), based on the total weight of the polymer.

18. The process according to claim 15, wherein polymerized unit (A) comprises at least one monomer selected from the group consisting of N-vinylpyrrolidone, N-vinylpiperidone, and N-vinylcaprolactame.

19. The process according to claim 15, wherein polymerized unit (A) comprises at least 80% by weight of N-viaylpyrrolidone, and 0 to 20% by weight of at least one monomer of (I) which is different from N-vinylpyrrolidone, based on the total weight of component (A).

20. The process according to claim 15, wherein polymerized unit (A) comprises at least 80% by weight of N-vinylpyrrolidone, and 0 to 20% by weight of N-vinylcaprolactam, based on the total weight of component (A).

21. The process according to claim 15, wherein polymerized unit (B) comprises at least 80% by weight of vinyl acetate, and 0 to 20% by weight of at least one monomer of formula (H) which is different from N-vinyl acetate, based on the total weight of component (B).

22. The process according to claim 15, wherein polymerized unit (B) comprises at least 80% by weight of vinyl acetate, and 0 to 20% by weight of at least one monovinyl ester of a C.sub.4 to C.sub.20 monocarboxylic acid, based on the total weight o component (B).

23. The process according to claim 15, wherein the polymer has a mass average molecular (Mw) in the range of 30 to 1000 kg/mol.

24. The process according to claim 15, wherein the polymer has a glass transition temperature in the range of 40 to 200C.

25. The process according to claim 15, wherein the viscosity of the polymer is in the range of 1 to 10,000 Pa.Math.s, measured at 240 C. at a shear rate of 10 rad/s.

26. The process according to claim 15, wherein the polymer comprises: 20 to 80% by weight of polymerized unit (A) consisting of N-vinylpyrrolidone and 80 to 20% by weight of polymerized unit (B) consisting of vinyl acetate, based on the total weight of the polymer.

27. The process according to claim 15, wherein the polymer comprises 20 to 80% by weight of polymerized unit (A) consisting of N-vinylpyrrolidone, 80 to 20% by weight of polymerized unit (B) consisting of vinyl acetate and 1 to 10% by weight of a polymerized. unit (C) consisting of N-vinylcaprolactam, based on the total weight of the polymer.

28. The process according to claim 15, wherein the polymer comprises 20 to 80% by weight of polymerized unit (A) consisting of N-vinylpyrrolidone, 80 to 20% by weight of polymerized unit (B) consisting of vinyl acetate and 1 to 10% by weight of a polymerized unit (C) consisting of at least one monovinyl ester of formula (III) ##STR00015## where R.sup.9 is a C.sub.3-C.sub.20-alkyl, based on the total weight of the polymer.

29. A fused filament fabrication process, the process comprising: modelling a structure around a support material comprising a polymer, wherein the polymer comprises polymerized units (A) and (B): (A) at least one first monomer of formula (I): ##STR00016## where n is 3 to 12; m is 0 to 3; R.sup.1 is C.sub.1-C.sub.10-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl; R.sup.2, R.sup.3 and R.sup.4 are each, independently of one another, hydrogen, C.sub.1-C.sub.10-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl; and (B) at least one second monomer of formula (II) ##STR00017## where R.sup.5, R.sup.6 and R.sup.7 are each, independently of one another, hydrogen, C.sub.1-C.sub.10-alkyl, C.sub.2C.sub.10-alkenyl, aryl or aralkyl; and R.sup.8 is C.sub.1-C.sub.20-alkyl, C.sub.2-C.sub.10-alkenyl, aryl or aralkyl.

Description

[0200] The present invention is illustrated below by reference to examples, without limitation thereto.

[0201] The following polymers where tested:

[0202] Comparative example 1 (C1): acrylic copolymer; trade name P400 SR obtained from Stratasys.

[0203] Comparative example (C2): N-vinylpyrrolidone K30 homopolymer

[0204] Comparative example (C3): N-vinylpyrrolidone K90 homopolymer

[0205] Inventive example (E4): Copolymer comprising polymerized units of N-vinylpyrrolidone and vinyl acetate

[0206] Inventive example (E5): Copolymer comprising polymerized units of N-vinylpyrrolidone, vinyl acetate and a monovinyl ester of a C.sub.4 to C.sub.20 monocarboxylic acid

[0207] The weight average molecular weights (Mw) where determined by gel permeation chromatography using polymethyl methacrylate standards (PSS Polymer standards services GmbH). The measurements were performed at an oven temperature of 40 C. with hexafluoroisopropanol (HFIP, with 0.05 wt % trifluoroacetic acid sodium salt). A HFIP-LG guard column in combination with two HFIPgel columns (i.D. of 7.5 mm and length of 30 cm) (Polymer Laboratories Ltd.) were used, along with a RI detector.

[0208] The viscosity of the polymers was measured at a temperature of 240 C. at a shear rate of 10 rad/s by means of rotation rheology measurements using a plate-plate configuration on a DHR-1 TA Instruments rotational rheometer. A frequency sweep was performed between 0.06 and 400 rad/s at a temperature of 240C.

[0209] The glass transition temperatures (T.sub.g) were measured by differential scanning calorimetry (DSC) according to DIN 53765 using a TA Instruments Q2000 and a temperature ramp speed of 20K/min.

[0210] The time for solubilisation was measured in distilled water or in an aqueous solution consisting of distilled water and 0.1M NaOH at a temperature of 20 C. Therefore 0.25 g of the polymer was placed in 50 ml of distilled water or an aqueous solution consisting of distilled water and 0.1M NaOH, respectively. The time required until no undissolved polymer remains was measured and was taken as the time for solubilisation.

[0211] The results are shown below in table 1.

TABLE-US-00001 TABLE 1 Viscosity at Time for solubilisation M.sub.w 10 rad/s T.sub.g [min] Example [kg/mol] [Pa*s] [ C.] Water 0.1M NaOH C1 140 835 94.5 insoluble 30 C2 50 9000 168 4 0.5 C3 1400 10000 176 4 3 E4 40 13 107 2.5 0.5 E5 190 1650 112 17 16

[0212] The polymers according to the invention (examples E4 and E5) show glass transition temperatures (T.sub.g) similar to that of conventionally used modeling materials. The viscosities of the polymers according to the invention make these polymers ideal for the use in a fused filament fabrication process. Moreover, the time for solubilisation is significantly shortened compared to support materials described in the state of the art.

[0213] The polymer according to comparative example C1 shows a suitable viscosity to be used in a fused filament fabrication process; however in water it is insoluble so that the removement of this support material is difficult. The polymers according to comparative examples C2 and C3 show good solubilisation times; however the high viscosities make them difficult to process. Moreover, these polymers are highly hygroscopic and therefore difficult to store.

[0214] As shown above the polymers according to the invention meet at one and the same time the requirements of high glass transition temperature, good compatibility with the modeling material, suitable viscosity and easy removability.

[0215] Table 2 gives results for blends of the support material used in comparative example (C3) and the support material used in inventive example E4, namely a blend of a N-vinylpyrrolidone K90 homopolymer (C3) and a copolymer comprising polymerized units of N-vinylpyrrolidone and vinylacetate (E4) .

[0216] Three-Point Bending Test

[0217] Unnotched charpy bars with dimensions (1048 mm) were injected after processing the buffered polymer on a DSM mini-extruder. The polymer was extruded twice for 2 min each using a screw-speed of 80 rpm. These were bars used as test specimens to determine the flexural modulus as well as the stress and elongation at break in flexural tension using an ISO 178:2010 test. The flex-rate was set at 2 mm/min. The tests were performed at room temperature (23 C.).

TABLE-US-00002 TABLE 2 Flexural mechanical Viscosity properties Content Content at 10 Flexural Elongation C3 E4 Mw rad/s Tg modulus at break Example [wt %] [wt %] [kg/mol] [Pa .Math. s] [ C.] [MPa] [%] E6 10 90 126 300 105 3642 0.7 E7 20 80 176 366 105 3660 1.07 E8 30 70 246 575 106 3712 0.96

[0218] The inventive examples E6, E7 and E8 show the good mechanical properties of the blends. They show a high stiffness together with a glass transition temperature (T.sub.g) and a viscosity that are ideal for the use in a fused filament fabrication process.