Use of multi-block copolymers as sacrificial material in 3D printing processes

Abstract

The present invention relates to the use of multi-block copolymer compositions as sacrificial materials for 3D fused deposition modeling.

Description

Technical Field

[0001] This invention relates to the use of multiblock copolymers or multiblock copolymer compositions as sacrificial materials for 3D fused deposition modeling. Only block copolymers are used in this invention. This excludes any other polymers having a structure in the form of a non-block copolymer.

[0002] These materials exhibit rapid dissolution or dispersion in a variety of solvents, and combined with thermomechanical properties, they are well-suited for manufacturing threaded parts or rods that can be used in 3D printing (fused deposition modeling) to support polymers that make up the parts to be manufactured, including polymers with high glass transition temperatures (Tg), and are then removed by dissolving them in solvents.

[0003] 3D printing (or 3D modeling) enables the additive manufacturing (or AM) of real objects based on virtual objects. It's based on slicing a 3D virtual object into very thin 2D slices. These slices are then deposited one after another, attached to previous slices, to reconstruct the real object. The materials used to construct this object include plastics (particularly acrylonitrile-butadiene-styrene (ABS) and polylactic acid (PLA)), but also polyaryletherketone (PAEK) and polyetherimide (PEI). wax Materials can be metals or ceramics. Examples of additive manufacturing technologies include fused filament fabrication (FFF) and laser sintering.

[0004] Fused deposition modeling (FDM) is a technique that melts a filament through an extrusion nozzle. A molten filament, approximately millimeters in diameter, is extruded from this nozzle. This filament is deposited onto a wire and then bonded to the previously deposited wire by remelting. This technique allows for the manufacture of parts from suitable materials that possess the same mechanical and thermal properties and stability as injection-molded thermoplastic parts, but are generally lighter. In the case of polymers, this technique requires a support structure for part production due to mechanical consolidation; this support structure is also extruded simultaneously. This structural support structure is made of a different material than that constituting the object being created, and it is removed from the object when the process of constructing the object is complete.

[0005] The structural support typically corresponds to a soluble or dispersible polymer composition with very precise specifications. Among the desired properties, in addition to mechanical strength, the copolymer's glass transition temperature (which must be similar to the glass transition temperature of the material to be printed), its thermal stability or processability, and its dissolution or dispersion kinetics in various solvents (especially water) are crucial. When the dissolution or dispersion solvent is water, the material must also be well preserved. This latter property is not always readily achieved, as water-soluble or water-dispersible compositions and filaments can prove difficult to store in humid environments. Agglomeration of particles or filament binding to spools has been observed during storage due to ambient humidity. Background Technology

[0006] This 3D printing technology requires support materials to enable the construction of complex parts; this is described, for example, in WO2010 / 045147. Other water-soluble support materials include:

[0007] - Polyvinyl alcohol

[0008] -Butene diol / vinyl alcohol (BVOH) copolymer

[0009] -(meth)acrylic acid copolymers.

[0010] These supporting polymer compositions always contain several copolymers, which serve to adjust parameters such as solubility and mechanical properties, making development more difficult.

[0011] Among other support materials that are soluble in other solvents, one could mention high-impact polystyrene (HIPS) that is soluble in limonene.

[0012] It is known in the prior art that the glass transition temperature (Tg) of the support must be relatively close to the glass transition temperature of the polymer constituting the object to be printed, within the order of 10°C lower than the Tg of the polymer constituting the object to be printed.

[0013] Otherwise, the construction of the part to be printed cannot be performed correctly because the support material exhibits too much creep. This is explained, for example, in US5866058.

[0014] Surprisingly, the applicant discovered that when block copolymers are used alone or in combination as sacrificial support materials, it is no longer necessary for the Tg of the material to be printed to be close to that of the support material. This provides an advantage because there are more possibilities for defining other properties of the support polymer. Therefore, if the Tg remains lower than that of the polymer constituting the object to be printed, it is easier to adjust other parameters, such as mechanical parameters or solubility parameters in aqueous media, without worrying about sacrificing the Tg of the support polymer. Thus, block copolymers with one of their blocks having a highest Tg of, for example, 50°C, can be used as support materials for constructing objects made of materials with Tg in the range of 50°C to 200°C. When combined with other block copolymers having at least one block with a glass transition temperature (Tg) below 0°C and at least one block with a Tg above 0°C, they provide compositions that also have very good mechanical properties.

[0015] This opens up new possibilities for printing objects made of polyaryletherketone (PAEK), polyetherimide (PEI), polyamide-imide (PAI), polysulfone (PSU), polyethersulfone (PES), and polyphenylene sulfide (PPS), for which the choice of sacrificial support polymers is very limited and has other drawbacks. Summary of the Invention

[0016] The use of at least one multiblock copolymer (I) as a sacrificial material in a process for 3D printing polymers selected from PEEK, PEKK, PEI, PAI, PSU, and PPS with a Tg between 140 and 200 °C, wherein the at least one multiblock copolymer (I) comprises at least one monomer M composed of i monomers M randomly linked together. i The constituent segments and at least one of j types of monomers M randomly connected together j The segments formed, where i is an integer from 2 to 5 (inclusive), and j is an integer from 2 to 5 (inclusive); M i The monomers selected are monomer A, whose homopolymer has a Tg below 0°C, and hydrophilic monomer B, with the mass ratio of A ranging from 80% to 95% and the mass ratio of B ranging from 5% to 20%.

[0017] M j The monomers are selected from monomer C, whose homopolymer has a Tg below 0°C, monomer D, whose homopolymer has a Tg above 25°C, and hydrophilic monomer E, with the mass ratios of monomers C, D, and E being between 25% and 35%, 25% and 35%, and 35% and 45%, respectively. Detailed Implementation

[0018] There is every reason to believe that any type of monomer having the characteristics and relevant proportions of the block copolymer (I) described in the invention will produce performance that is conducive to solving the technical problems described in the background art.

[0019] The chemicals used were not anticipated.

[0020] However, there are very few chemicals that allow for the preparation of such a structure in block copolymers.

[0021] The reactive blocks can be prepared, for example, by polycondensation or ring-opening, so that other blocks can be linked in a second step, the selection and proportion of monomers being as described in the invention.

[0022] Blocks can also be prepared in the same way by free radical or anionic polymerization, i.e., block-by-block, so that other blocks can be connected together step by step, with the selection and proportion of monomers as described in the invention.

[0023] In preferred techniques, controlled radical polymerization will be used because it allows block copolymers to be obtained in sequential steps within the same process operation.

[0024] RAFT (Radical Addition Fragmentation Transfer) or NMP (Nitrogen Oxide-Mediated Polymerization) may be mentioned in a non-limiting manner.

[0025] NMP is preferably selected, and more preferably, NMP of the anti-radical N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl oxynitride is used. This anti-radical is widely described and used in the literature and is employed by alkoxyamines or poly(poly)alkoxyamines of 2-([tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino]oxy)-2-methylpropionic acid.

[0026] Regarding the monomers of the block copolymer (I) described in the invention, monomer A is selected from the following:

[0027] Alkyl methacrylates (the alkyl group having a straight or substituted C4-C18 chain and optionally containing oxygen), particularly the following monomers: butyl acrylate (buA), 2-ethylhexyl acrylate (2EHA), methoxyethyl acrylate (MEA), lauryl methacrylate (lauMA), and stearyl methacrylate (SMA).

[0028] Monomer B is selected from the following: acrylic acid (AA), methacrylic acid (MAA), styrene sulfonate / ester, 2-acrylamido-2-propanesulfonic acid.

[0029] Monomer C is selected from the following:

[0030] Alkyl methacrylates (the alkyl group having a straight or substituted C4-C18 chain and optionally containing oxygen), particularly the following monomers: butyl acrylate (buA), 2-ethylhexyl acrylate (2EHA), methoxyethyl acrylate (MEA), lauryl methacrylate (lauMA), and stearyl methacrylate (SMA).

[0031] Monomer D is selected from the following:

[0032] Styrene (S); methyl methacrylate (MMA), acrylonitrile (AN), isobornyl acrylate.

[0033] Monomer E is selected from the following: acrylic acid (AA) and methacrylic acid (MAA).

[0034] Preferably, A is butyl acrylate or 2-ethylhexyl acrylate, more preferably butyl acrylate; B is acrylic acid or methacrylic acid; C is butyl acrylate or 2-ethylhexyl acrylate, more preferably butyl acrylate; D is styrene, acrylonitrile, methyl methacrylate or isobornyl acrylate, more preferably styrene or isobornyl acrylate; and E is acrylic acid or methacrylic acid.

[0035] Polymers printed using the sacrificial polymer compositions of the present invention can have a glass transition temperature (Tg) higher than 50°C, wherein polylactic acid (PLA), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylonitrile (ASA), polyamide (PA), polycarbonate (PC), polymethyl methacrylate (PMMA), copolyesters (e.g., polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyolefins (PE, PP)), and, for polymers having a high Tg between 140 and 200°C, polyaryletherketone (PAEK) (represented according to the aryl etherketone sequence as PEEK, PEKK, PEK, PAKEKK, PEEKK, PEKK), polyetherimide (PEI), polyamide-imide (PAI), polysulfone (PSU), polyethersulfone (PES), or polyphenylene sulfide (PPS) may be mentioned without limitation.

[0036] Block copolymers are particularly useful as water-soluble support materials for high-temperature polymers such as PEEK, PEKK, PEI, PAI, PSU, and PPS. Other polymers with lower Tg mentioned can also be printed, but other solutions already exist.

[0037] Therefore, the preferred scope of the invention extends to the use of block copolymers described in the invention to print polymers with a Tg between 50 and 200°C, preferably between 140 and 200°C.

[0038] The block copolymer (I) described in the invention is preferably a diblock copolymer or a triblock copolymer, more preferably a diblock copolymer. In the definition of these copolymers, i can take a value between 2 and 5, preferably between 2 and 3 (including the limit), more preferably 2. In the definition of these copolymers, j can take a value between 2 and 5, preferably between 2 and 3 (including the limit), more preferably 3.

[0039] They have blocks (block 1) composed of group A and group B monomers in a mass ratio of 5% to 40% (preferably between 10% and 30%), and blocks (block 2) composed of monomers C, D and E in a mass ratio of 50% to 90% (preferably between 60% and 80%).

[0040] In a non-limiting manner, the performance balance associated with the selection of monomers in this invention enables these copolymers to be soluble in solvents selected from water, DMSO, alcohols, or ketones. Water is a preferred solvent in a pH range of 7 to 12, preferably 10 to 12.

[0041] In addition to the block copolymers (I) used in this invention, these can also be combined with at least one block polymer (II). Therefore, this invention also relates to the use of combinations of copolymers (I) and (II) as sacrificial material compositions in 3D printing processes.

[0042] Block copolymers (II) are preferably diblock copolymers or triblock copolymers, more preferably triblock copolymers. They are prepared using the same type of polymerization chemistry and process as block copolymers (I), and according to the same type of preference for polymerization chemistry and process.

[0043] The copolymer (II) has at least one block with a glass transition temperature (Tg) below 0°C and at least one block with a Tg above 0°C.

[0044] Regarding the monomers of the block copolymer (II), they are selected from the following:

[0045] For blocks with a Tg below 0°C, the selection is made from butyl acrylate, 2-ethylhexyl acrylate, and preferably butyl acrylate.

[0046] For blocks with a Tg above 0°C, the composition is selected from methyl methacrylate, styrene, acrylic acid, methacrylic acid, dimethacrylamide, isopropylacrylamide, and isobornyl acrylate, with methyl methacrylate, dimethacrylamide, isobornyl acrylate, and isopropylacrylamide being preferred. In the case of dimethacrylamide or isopropylacrylamide, the mass percentage of the composition relative to the total amount of (II) is between 1% and 30%, preferably between 5% and 15%.

[0047] When the dissolving or dispersing solvent is water, the compositions of the present invention exhibit very good solubility at high pH values ​​(e.g., 12) with or without copolymer (II), but much poorer solubility at pH 7. This provides an advantage because spools of threads produced from these copolymers have better storage stability, especially in humid environments.

[0048] The copolymer (I) described in the invention has a weight-average molecular weight between 80,000 and 150,000 g / mol and a dispersibility index between 1 and 3, preferably between 1.5 and 2.5, as measured by using the SEC of a polystyrene standard.

[0049] They can be blended with other block copolymers to adjust certain properties.

[0050] The block copolymer (II) has a weight-average molecular weight between 50,000 and 150,000 g / mol and a dispersibility index between 1 and 3, preferably between 1.5 and 2.5, as measured by using the SEC of a polystyrene standard.

[0051] These block copolymers (II) can be used in the composition in proportions of 1% to 50% by mass (preferably 3% to 15% by mass) of the total weight of (I) + (II).

[0052] The glass transition temperature (Tg) was measured by DSC.

[0053] Figure 1 The DMA performance of the sacrificial polymer (I) and its combination with copolymer (II) (sacrificial polymer + 5% M52N) is described.

[0054] Example:

[0055] Example 1 - Synthesis of copolymer (I) P(BA-AA)–b–P(BA-S-MAA)

[0056] This embodiment involves a diblock copolymer iMi-jMj, where i=2 and j=3, denoted as mMnN-block-oOpPqQ.

[0057] Segment 1:

[0058] M: Butyl acrylate (buA), m = 90% of block 1.

[0059] N: Acrylic acid (AA), n = 10% of block 1.

[0060] Segment 2:

[0061] O:buA, o = 30% of segment 2.

[0062] P: Styrene (S), p = 30% of block 2.

[0063] Q: Methacrylic acid (MAA), q = 40% of block 2.

[0064] The synthesis of this diblock copolymer is carried out in two steps:

[0065] The first block P(BA–AA) was synthesized from bulk, and then the unreacted monomers were stripped.

[0066] The second block P(BA-S–MAA) was synthesized in a solvent.

[0067] 1.1. Synthesis of block P(BA–AA)

[0068] The first block was synthesized using a bulk polymerization process in an Ingenieur Büro reactor.

[0069] Reactants:

[0070] -Butyl acrylate (BA)

[0071] 208.7 g

[0072] - Acrylic acid (AA)

[0073] 22.9 g

[0074] -BlocBuilder®

[0075] 2.51 g

[0076] The goal is to achieve a number-average molecular weight of 27,000 g / mol with a conversion rate of 70%.

[0077] The reactants were weighed and mixed under magnetic stirring, then introduced into the reactor under vacuum pressure. The reactor was stirred (250 rpm). The medium was degassed by three cycles of alternating nitrogen pressure and vacuum. Polymerization occurred in three temperature phases: 105°C for 60 minutes, then 110°C for 90 minutes. The total polymerization time was 300 minutes. Conversion was monitored by dry extract, with samples taken hourly (at 150°C thermal equilibrium and in a 125°C vacuum oven).

[0078] When the target conversion rate is reached, lower the temperature to 80°C. Once the setpoint is reached, gradually place the apparatus under vacuum and distill the unreacted monomers (recovering them in a liquid nitrogen trap). Incubate the system at 80°C and maximum vacuum for approximately 90 minutes. When distillation is complete, lower the setpoint to 40°C, and once this setpoint is reached, introduce 160 g of toluene (under vacuum pressure) to dilute the medium. Stir the system at 40°C for several hours to ensure complete homogenization. Then collect the solution.

[0079] 1.2. Synthesis of block P(BA-S–MAA)

[0080] The synthesis was carried out in a solvent process using an ethanol / toluene mixture at a mass ratio of 60 / 40. The solvent was used at 45% relative to the total feedstock.

[0081] A mixture of BA / S / MAA with a mass ratio of 30 / 30 / 40 was introduced.

[0082] The goal is a copolymer P(BA-AA)-bP(BA-S-MAA) with a 30 / 70 mass composition and a 70% conversion of the second block.

[0083] The preparation of the raw materials is as follows:

[0084] The first block diluted in ethanol: 154.8 g

[0085] BA / S / AMA:154.8 / 154.8 / 206.4(g)

[0086] Ethanol / Toluene 329 / 219.5 (g)

[0087] The molar mass (PS equivalent) of the copolymer is as follows:

[0088] Mp = 95000 g / mol

[0089] Mn = 53000 g / mol

[0090] Mw = 95000 g / mol

[0091] PI = 1.81

[0092] In Examples 2 to 4 (of the present invention 2 to 4), the iMi-jMj diblock copolymer (where i=2 and j=3, denoted as mMnN-block-oOpPqQ) was prepared under the same synthesis conditions as in Example 1, with the same ratio of blocks and the same ratio of monomers. The following monomers were selected in Table 1:

[0093] [Table 1]

[0094]

[0095] The proportions m, n, o, p, and q remained the same as those in Example 1. The resulting polymers exhibited similar molecular weight properties, with a molecular weight variation of no more than 10% compared to the polymers obtained in Example 1.

[0096] Example 5: Solubility Test

[0097] Testing was conducted on the particles of the support material of this invention and commercially available Aquasis. ® Products 120 and 180 dissolve completely.

[0098] The granules were prepared by pressing at 200°C. Dissolution of the granules was carried out at pH 7 and pH 12 and at 60°C.

[0099] Example 6: Filament Extrusion:

[0100] The coil is formed directly from the material of this invention.

[0101] Spinning was performed on a single-screw "Labtech LBE20-30 / C" extruder (screw diameter: 20 mm). The bar was removed at a constant speed (9.1-9.4 m / min) using a caterpillar haul-off device.

[0102] Adjust the extruder and gear pump to 190°C.

[0103] The screw speed of the extruder is 30-34 rpm, and the pressure is P=55 bar.

[0104] Commercial comparison product Aquasis ® 120 and Aquasis ® The 180 is supplied in the form of a spool and can be used directly in 3D printing equipment.

[0105] Example 7: 3D Printing

[0106] The parts were printed on an "Original Prusa i3 MK3S+" 3D printer. Other available printers may also be used. Sacrificial resin in filament form according to the invention, or Aquasis® 180 control, was printed onto a plate at 250°C and a speed of 40 mm / s, with the first layer at 122°C and subsequent layers at 120°C. The layer height was 0.2 mm, and the infill was 100% concentric.

[0107] The sacrificial resin in filament form according to the invention or Aquasis® 120 control is printed onto a plate at a temperature of 220°C and a speed of 10 mm / s, with the first layer at 120°C and subsequent layers at 105°C. The layer height is 0.2 mm, and the filler is 100% concentric.

[0108] The polymer resin for the part to be constructed is printed under the following conditions:

[0109] ABS, 3DFilTech: 250℃; 10 mm / s.

[0110] PLA, eMotion TECH: 210℃; 10 mm / s.

[0111] PEI: ThermaX PEI-Ultem 9085: 360℃; 10 mm / s.

[0112] PEKK, ThermaX PEKK 3DXTech: 360°C; 10 mm / s.

[0113] The constructed part is a 4 cm x 1 cm x 0.5 cm sacrificial polymer rod (in this invention and control), on which rods of the same size are constructed using target polymers (PLA, ABS, PEKK, PEI, etc.).

[0114] Example 8:

[0115] Once the part is constructed, when possible (depending on whether a control sacrificial resin or the sacrificial resin of this invention is used with a given polymer to be printed), the entire part is immersed in water at 60°C and pH 7 or 12, and the time it takes for all the sacrificial material to dissolve is recorded. When this test is deemed impossible, it means that the part to be constructed does not meet the requirements for 3D digital molding.

[0116] The results of the dissolution and 3D printing tests are shown in Table 2:

[0117] [Table 2]

[0118]

[0119] T1: Total dissolution time (in minutes) at 60°C and pH 7.

[0120] T2: Total dissolution time (in minutes) at 60°C and pH 12.

[0121] It can be seen that, regardless of the polymer to be printed in Table 2, the sacrificial resin of the present invention can support the polymer to be printed.

[0122] Example 9:

[0123] The mechanical properties of the sacrificial polymer 1 of the present invention were evaluated by tensile testing with or without the addition of copolymer (II).

[0124] Measurements were performed on a filament 14 cm in length and 1.75 mm in diameter. Elongation at break was measured using a Zwick Roell Z005 instrument with a 5 kN sensor at a speed of 5 mm / min and a jaw spacing of 61 mm.

[0125] The tested copolymer (II) can be branded Nanostrength ® Commercially available, reference numbers M52N and M65N. These copolymers conform to the description for copolymer (II) in terms of composition and molecular weight. They are added in amounts of 5% by mass and 10% by mass, respectively.

[0126] Table 3 shows the assessments conducted:

[0127] [Table 3]

[0128]

[0129] It was found that the addition of copolymer (II) improved the elongation at break and maintained this elongation after one month of storage.

[0130] As shown in Table 4, the solubility of some materials in Example 9 (with and without copolymer (II)) was affected at 60°C and pH 12, and it was shown that the presence of copolymer (II) had only a minor adverse effect.

[0131] [Table 4]

[0132]

[0133] The materials of Example 1 (I) and Example 9 (I+II) using 5% M52N were tested using DMA (Dynamic Mechanical Analysis). Curve 1 shows that the rheological properties of the two materials are very similar.

Claims

1. The use of at least one multiblock copolymer I as a sacrificial material in a process for 3D printing polymers selected from PEEK, PEKK, PEK, PEKEKK, PEEKK, PEI, PAI, PSU, and PPS with a Tg between 140 and 200 °C, wherein the at least one multiblock copolymer I comprises at least one monomer M randomly linked together. i The constituent segments and at least one of j types of monomers M randomly connected together j The segments formed, where i is an integer from 2 to 5, inclusive, j is an integer from 2 to 5, inclusive; M i The monomer A, whose homopolymer has a Tg below 0°C, and the hydrophilic monomer B, are selected from the monomer A, which has a mass percentage in the range of 80% to 95%, and the mass percentage B has a mass percentage in the range of 5% to 20%. M j The monomers are selected from monomer C, whose homopolymer has a Tg below 0°C, monomer D, whose homopolymer has a Tg above 25°C, and hydrophilic monomer E, wherein the mass ratios of monomers C, D, and E are between 25% and 35%, 25% and 35%, and 35% and 45%, respectively.

2. The use as described in claim 1, wherein, At least one block copolymer II is present in a mass ratio of 1% to 50% of the total weight of the multiblock copolymer I and the block copolymer II.

3. The use as described in claim 1 or 2, wherein, The at least one multiblock copolymer I is a diblock copolymer or a triblock copolymer.

4. The use as described in claim 3, wherein, The multiblock copolymer I is a diblock copolymer.

5. The use as described in claim 4, wherein, The diblock copolymer has a block 1 composed of group A and group B monomers in a mass ratio of 5% to 40% and a block 2 composed of monomers C, D and E in a mass ratio of 50% to 90%.

6. The use as described in claim 2, wherein, The block copolymer II has at least one block with a glass transition temperature below 0°C and at least one block with a glass transition temperature above 0°C.

7. The use as described in claim 2, wherein, The multiblock copolymer I and / or the block copolymer II are prepared by controlled free radical polymerization.

8. The use as described in claim 7, wherein, The multiblock copolymer I and / or the block copolymer II are prepared by oxynitride-mediated free radical polymerization.

9. The use as described in claim 8, wherein, The multiblock copolymer I and / or the block copolymer II are prepared by free radical polymerization mediated by N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl oxynitride.

10. The use as described in claim 8, wherein, At least one multiblock copolymer I is composed of block 1 using butyl acrylate and acrylic acid and block 2 using butyl acrylate, styrene and methacrylic acid.

11. The use as described in claim 1, wherein, The weight-average molecular weight of at least one multiblock copolymer I is between 80,000 g / mol and 150,000 g / mol.

12. The use as described in claim 2, wherein, The weight-average molecular weight of the block copolymer II is between 50,000 g / mol and 150,000 g / mol.

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