USE OF MULTIBLOCK COPOLYMERS AS SACRIFICIAL MATERIAL IN A 3D PRINTING PROCESS

Abstract

The present invention relates to the use of multiblock copolymer compositions as sacrificial materials of 3D fused deposition modeling.

Description

[0001] DESCRIPTION

[0002] TITLE: Use of multi-block copolymers as sacrificial material in a 3D printing process

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to the use of multi-block copolymers or multi-block copolymer compositions as sacrificial materials for 3D modeling by fused deposition modeling. Only block copolymers are used in this invention. This excludes any other architectural polymer not in the form of block copolymers.

[0005] Such materials exhibit rapid solubilization or dispersibility in a variety of solvents while combining the ideal thermomechanical properties to make them into wires or rods usable in 3D printing (fused deposition modeling) to support polymers constituting the part to be manufactured, including polymers with a high glass transition temperature (Tg), before being removed by dissolution in a solvent.

[0006] Three-dimensional printing (or 3D printing) allows the additive manufacturing (AM) of a real object from a virtual object. It is based on cutting the virtual 3D object into very thin 2D strips. These thin strips are deposited one by one by fixing them on the previous ones, which reconstitutes the real object. Among the materials constituting the object, we find plastic materials (notably acrylonitrile butadiene styrene (or ABS) and polylactic acid (or PLA)), but also Polyaryletherectones (PAEK), Polyetherimides (PEI), wax, metal or ceramics. Examples of additive techniques are fused filament fabrication (FFF) and laser sintering.

[0007] Fused Filament Deposition Modeling is a technique that involves melting a filament through an extrusion nozzle. From this nozzle emerges a molten filament, with a diameter of around one millimeter. This wire is deposited in line and is bonded by re-melting to what was previously deposited. This technique makes it possible to create parts made of good material, with mechanical and thermal characteristics and stability identical to injected thermoplastic parts and often lighter. In the case of polymers, for reasons of mechanical consolidation, this technique requires a support for the production of the parts, also extruded together. This construction support is made of a different material than that constituting the created object, a support which is eliminated from said object, when the construction process of the latter is finished.

[0008] The construction support is generally a soluble or dispersible polymer composition meeting very precise specifications. Among the desired properties, in addition to mechanical strength, the glass transition temperature of the copolymer, which must be close to the material to be printed, its thermal stability or ease of processing, the kinetics of solubilization or dispersion in a variety of solvents, particularly water, is of prime importance. The material must also have good preservation, when the solubilization or dispersion solvent is water. This last characteristic is not always easy to establish because water-soluble or water-dispersible compositions and filaments in water can be difficult to store in a humid atmosphere. Granules caking or filaments sticking to the spools are observed due to the presence of ambient humidity during storage.

[0009] TECHNICAL BACKGROUND

[0010] This 3D printing technique requires support materials that allow the construction of complex parts, this is for example described in W02010 / 045147. Other water-soluble support materials include:

[0011] Polyvinyl alcohol

[0012] BVOH butenediol / vinyl alcohol copolymer.

[0013] (Meth)acrylic copolymers.

[0014] These carrier polymer compositions always include several copolymers, whose role is to adjust solubility, mechanical properties or other parameters, resulting in more difficulties in development.

[0015] Other carrier materials soluble in other solvents include, for example, high impact polystyrene (HIPS), which is soluble in limonene.

[0016] It is known in the prior art that the support must have a glass transition temperature (Tg) relatively close to that of the polymer constituting the object to be printed within an order of magnitude 10°C lower than the Tg of the polymer constituting the object to be printed.

[0017] Otherwise, the construction of the part to be printed is not done correctly because the support material has too much creep. This is explained for example in US5866058.

[0018] Surprisingly, the applicant has found that when block copolymers are used alone or in combination as a sacrificial support material, this condition of proximity of the Tg of the materials to be printed - support material is no longer necessary. This presents an advantage because the definition of the other characteristics of the support polymer presents many more possibilities. It is thus easier to adjust the other parameters such as mechanical or solubilization in an aqueous medium without worrying about the Tg of the sacrificial support polymer, provided that they remain lower than that of the polymer constituting the object to be printed. Thus, with block copolymers whose highest Tg of one of the blocks is, for example, 50°C, such block copolymers can be used as a support material to construct objects made of material with a Tg ranging from 50°C to 200°C.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 a composition which also has very good mechanical properties.

[0019] This offers new possibilities for printing objects made of poly aryl ether ketones (PAEK), polyether imides (PEI), polamide-imide (PAI), polysulfone (PSU), poly(ethersulfone) (PES), poly(phenylene sulfide) (PPS) for which the choice of sacrificial support polymers is very limited and has other disadvantages. Summary of the invention:

[0020] Use of at least one multi-block copolymer (I) as a sacrificial material in a 3D printing process for polymers with a Tg of between 140 and 200°C. Chosen from PEEK, PEKK, PEI, PAI, PSU, and PPS, at least one multi-block copolymer(s) (I) comprising at least one block consisting of i monomers M± linked together in a statistical manner, i being an integer ranging from 2 to 5, limits included, and at least one block consisting of j monomers M j statistically linked, j being an integer ranging from 2 to 5, limits included, M± being selected from monomers A whose Tg of their homopolymers is less than 0°C and hydrophilic monomers B, the mass proportion of A varying from 80 to 95% and the mass proportion of B varying from 5 to 20%. M jbeing selected from monomers C whose Tg of their homopolymers is less than 0°C, monomers D whose Tg of their homopolymers is greater than 25°C and hydrophilic monomers E, the mass proportions of monomers C, D, E being respectively between 25-35%, 25-35%, 35-45%.

[0021] Detailed description

[0022] There is every reason to believe that any type of monomers having the characteristics and the associated proportions in block copolymers (I) as described in the summary of the invention lead to behavior favorable to the resolution of the technical problems as described in the technological background.

[0023] This does not prejudge the chemistry used. However, few chemistries allow the preparation of such structures in block copolymers.

[0024] For example, reactive blocks can be prepared by polycondensation or ring opening so that other blocks can be linked in a second step, with choices and proportions of monomers according to the summary of the invention.

[0025] The blocks can also be prepared by radical or anionic polymerization in the same way, i.e. block by block, so that other blocks can be linked in stages with choices and proportions of monomers according to the summary of the invention.

[0026] Among the preferred techniques, controlled radical polymerizations will be used because they make it possible to obtain block copolymers in sequential steps within the same process operation.

[0027] Examples include RAFT (Radical Addition Fragmentation Transfer) and NMP (Nitroxide Mediated Polymerization) in a non-limiting manner.

[0028] Preferably, NMP will be chosen, and preferably that which implements the counter radical N-tert-Butyl-1-diethylphosphono-2,2-dimethylpropyl Nitroxide. Such a counter radical is widely described and used in the literature and implemented through the alkoxyamine or polyalkoxyamines of 2-([tert-butyl[1-

[0029] (diethoxyphosphoryl)-2,2-dimethylpropyl ]amino]oxy)-2 methylpropionic acid.

[0030] With regard to the monomers of the block copolymers (I) as described in the summary of the invention, the monomers A will be chosen from the following: Oxygenated or non-oxygenated alkyl (meth)acrylates with a C4-C18 chain, linear or substituted and in particular the following monomers: Butyl acrylate (Abu), 2-ethylhexyl acrylate (AE2H), methoxyethyl acrylate (AME), Lauryl methacrylate (MAlau), stearyl methacrylate (MAS).

[0031] Monomers B will be chosen from the following: acrylic acid (AA), methacrylic acid (AMA), styrene sulfonate, 2-acrylamido-2-propane sulfonic acid. Monomers C will be chosen from the following:

[0032] Oxygenated or non-oxygenated alkyl (meth)acrylates with a C4-C18 chain, linear or substituted and in particular the following monomers: Butyl acrylate (Abu), 2-ethylhexyl acrylate (AE2H), methoxyethyl acrylate (AME), LAuryl methacrylate (MAlau), stearyl methacrylate (MAS).

[0033] The monomers D will be chosen from the following:

[0034] Styrene (S); Methyl methacrylate (MMA), Acrylonitrile (AN), Isobornyl acrylate.

[0035] The monomers E will be chosen from the following: acrylic acid (AA), methacrylic acid (AMA).

[0036] Preferably, A is butyl or 2-ethylhexyl acrylate, and more preferably butyl acrylate, B is acrylic acid or methacrylic acid, C is butyl or 2-ethylhexyl acrylate, and more preferably butyl acrylate, D is styrene, acrylonitrile, methyl methacrylate or isobornyl acrylate, and more preferably styrene or isobornyl acrylate, E is acrylic acid or methacrylic acid.

[0037] The polymers that can be printed using the sacrificial polymer compositions of the invention have glass transition temperatures (Tg) greater than 50°C, among which we can cite, without limitation, polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylonitrile (ASA), polyamides (PA), polycarbonate (PC), polymethyl methacrylate (PMMA), copolyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyolefins (PE, PP), and for polymers with a high Tg between 140 and 200°C, polyaryl ether ketones (PAEK), called PEEK, PEKK, PEK, PEKEKK, REEKK, REKK depending on the aryl-ether ketone chains, polyether imides (PEI), polamide-imide (PAI), polysulfone (PSU), poly(ethersulfone) (PES), or poly(phenylene sulfide) (PPS).

[0038] The use of block copolymers as water-soluble support materials for high-temperature polymers such as PEEK, PEKK, PEI, PAI PSU, and PPS is particularly useful. The other lower Tg polymers mentioned can also be printed, but other solutions already exist.

[0039] Thus, the preferences of the invention are for the use of block copolymers as described in the summary of the invention for printing polymers whose Tg is between 50 and 200°C, and preferably whose Tg is between 140 and 200°C.

[0040] The block copolymers (I) as described in the summary of the invention are preferably di or tri block copolymers, and more preferably di block copolymers. In the definition of these copolymers, i can take values ​​between 2 and 5, preferably between 2 and 3, inclusive, and more preferably 2. In the definition of these copolymers, j can take values ​​between 2 and 5, preferably between 2 and 3, inclusive, and preferably 3.

[0041] They have a mass proportion of blocks made up of monomers from family A and B varying from 5 to 40% (block 1), preferably between 10 and 30% and a mass proportion of blocks made up of monomers C, D, and E varying from 50 to 90% (block 2), preferably between 60 and 80%.

[0042] The balance of properties associated with the choices of monomers selected in the invention allows these copolymers to be soluble in solvents chosen from water, DMSO, alcohols, or ketones in a non-limiting manner. Water is the preferred solvent in a pH range which can vary from 7 to 12 and preferably from 10 to 12. In addition to the block copolymers (I) used in the invention, they can be combined with at least one block copolymer (II). Thus, the invention also relates to the use of the combination of copolymers (I) and (II) as a sacrificial material composition in a 3D printing process.

[0043] The block copolymers (II) are preferably di- or tri-block copolymers, and more preferably tri-block copolymers. They are prepared with the same type of polymerization process and chemistry and according to the same type of polymerization process and chemistry preferences as for the block copolymers (I).

[0044] The copolymers (II) have at least one block whose glass transition temperature (Tg) is less than 0°C and at least one block whose Tg is greater than 0°C. As regards the monomers of the block copolymers (II), they will be chosen from the following:

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

[0046] For blocks having a Tg greater than 0°C, methyl methacrylate, styrene, acrylic acid, methacrylic acid, dimethyl acrylamide, isopropylacrylamide, isobornyl acrylate, and preferably methyl methacrylate, dimethyl acrylamide, isobornyl acrylate and isopropyl acrylamide with mass proportions in the case of dimethyl acrylamide or isopropylacrylamide of between 1 and 30% by mass and preferably between 5 and 15% relative to the total of (II).

[0047] When the dissolution or dispersion solvent is water, the compositions of the invention in the presence or absence of the copolymer (II) exhibit very good solubilization at high pHs, 12 for example, and much less good solubilization at pH 7. This provides an advantage because the coils of wires manufactured with these copolymers exhibit better storage stability, particularly in a humid atmosphere.

[0048] The copolymers (I) as described in the summary of the invention have a molecular weight by weight of between 80,000 and 150,000 g / mol and a dispersity index of between 1 and 3, and preferably between 1.5 and 2.5) measured by SEC using polystyrene standards. They can be mixed with other block copolymers to adjust certain properties. The block copolymers (II) have a molecular weight by weight of between 50,000 and 150,000 g / mol and a dispersity of between 1 and 3, and preferably between 1.5 and 2.5) measured by SEC using polystyrene standards.

[0049] These block copolymers (II) can be used in the use of the composition in proportions varying from 1 to 50%, preferably between 3 and 15% by mass of the total weight (I) + (II).

[0050] Glass transition temperatures (Tg) are measured by DSC.

[0051] Figure 1 describes the DMA behavior of a sacrificial polymer (I) and its association with a copolymer (II) (sacrificial polymer + 5% M52N)

[0052] Examples:

[0053] Example 1 - Synthesis of a copolymer (I) P(BA - AA) - b - P(BA - S - AMA)

[0054] In this example we are targeting a di-block copolymer iMi-jMj, with i=2 and j=3 represented mMnN-block-oOpPqQ.

[0055] Block 1:

[0056] M: Butyl acrylate (Abu), m= 9% of block 1 N: Acrylic acid (AA), n= 10% of block 1.

[0057] Block 2:

[0058] O: Abu, o= 30% of block 2.

[0059] P: Styrene (S), p= 30% of block 2

[0060] Q: Methacrylic acid (MAA), q= 40% of block 2.

[0061] The synthesis of this di-block copolymer takes place in two stages:

[0062] 1 er P(BA - AA) block in bulk then stripping of the unreacted monomers. 2 ndP(BA - S - AMA) block in solvent 1.1. Synthesis of the P(BA - AA) block

[0063] The synthesis of this first block is carried out by a mass polymerization process using an Engineer Büro type reactor. Reagents: butyl acrylate (BA)

[0064] 208.7 g acrylic acid (AA)

[0065] 22.9 g

[0066] BlocBuilder ®

[0067] 2.51 g

[0068] A number-average molecular weight of 27,000 g / mol at 70% conversion is targeted.

[0069] The reactants are weighed and then mixed under magnetic stirring, then introduced into the reactor by vacuum. The reactor is stirred (250 rpm). The medium is degassed by alternating three times a nitrogen pressure and a vacuum. The polymerization is carried out in three temperature stages: 105°C for 60 min then

[0070] 110°C for 90 min. The polymerization time is 300 min. The conversion is monitored by dry extracts, samples are taken every hour. (thermo balance 150°C and vacuum oven 125°C).

[0071] When the target conversion is reached, the temperature is lowered to 80°C. Once the set point is reached, the equipment is gradually put under vacuum, the unreacted monomers will be distilled (recovery in liquid nitrogen traps). We remain at 80°C and under maximum vacuum for approximately 90 minutes. When the distillation is complete, the set point is lowered to 40°C. Once this set point is reached, 160g of toluene is introduced (by depression) in order to dilute the medium. We leave it for a few hours under stirring and at 40°C in order to homogenize the solution. This solution is then recovered.

[0072] 1.2. Synthesis of the P(BA - S - AMA) block We work in a solvent process, using an ethanol / toluene mixture with a mass ratio of 60 / 40. We work with 45% of solvent compared to the total charge.

[0073] A BA / S / AMA mixture with a mass ratio of 30 / 30 / 40 is introduced.

[0074] We are aiming for a P(BA - AA) - b - P(BA - S- AMA) copolymer with a mass composition of 30 / 70 with a conversion of 2 nd 70% block.

[0075] The charge is prepared as shown below: 1 er block diluted in ethanol: 154.8 g

[0076] BA / S / AMA: 154.8 / 154.8 / 206.4 (g)

[0077] Ethanol / Toluene: 329 / 219.5 (g)

[0078] The molar masses (PS equivalent) of this copolymer are as follows: Mp=95000 g / mol

[0079] Mn=53000 g / mol Mw=95000 g / mol Ip=l.81

[0080] In Examples 2 to 4 (inventions 2 to 4) di-block copolymers iMi-jMj are prepared, with i= 2 and j=3 represented mMnN-block-oOpPqQ with the same block ratio and the same proportions of monomers under the same synthesis conditions as for Example 1. In Table 1 the following monomers are selected:

[0081] [Table 1]

[0082] The proportions m, n, o, p, q remain identical to those of example 1. The polymers obtained have similar molecular mass characteristics not varying more than 10% in comparison with those obtained in example 1.

[0083] Example 5: dissolution tests.

[0084] The tests are carried out until a pellet of support material of the invention and the Aquasis products is completely dissolved. ® 120 and 180 available on the market.

[0085] The pellets are prepared by compression at 200°C. The pellets are dissolved at pH=7 and pH=12 at a temperature of 60°C.

[0086] Example 6: Filament extrusion:

[0087] Coils were formed directly from the materials of the inventions.

[0088] Spinning is carried out on a single-screw extruder "Labtech LBE20-30 / C" (screw diameter: 20mm). A caterpillar puller is used to drive the rod at a constant speed (9.1-9.4m / min).

[0089] The extruder and gear pump are set at 190°C. The extruder screw speed is 30-34 rpm, with a pressure P=55 bar.

[0090] Aquasis Trademark Products ® 120 and Aquasis ® 180 are available in the form of spools of wire that can be used directly in a 3D printing device.

[0091] Example 7: 3D Printing The parts were printed on an “Original Prusa i3 MK3S+” 3D printer. Other available printers can be used. The sacrificial resin in the form of filament according to the invention or the Aquasis® 180 control are printed at a temperature of 250°C on a plate at 122°C for the first layer then 120°C for the following layers at a speed of 40mm / s. The layer heights are 0.2mm and the filling is 100% concentric.

[0092] The sacrificial resin in the form of filament according to the invention or the Aquasis® 120 control are printed at a temperature of 220°C on a plate at 120°C for the first layer then 105°C for the following layers at a speed of 10mm / s. The layer heights are 0.2mm and the filling is 100% concentric.

[0093] The polymer resins of the parts to be built are printed under the following conditions:

[0094] ABS, 3DFilTech: 250°C; 10mm / s.

[0095] PLA, eMotion TECH: 210°C; 10mm / s.

[0096] PEI: ThermaX PEI - Ultem 9085: 360°C; 10mm / s.

[0097] PEKK, ThermaX PEKK 3DXTech: 360°C; 10mm / s.

[0098] The constructed parts are 4cm X 1cm X 0.5cm bars of a sacrificial polymer bar (invention and control) on which a bar of identical dimension is constructed using the target polymer (PLA, ABS, PEKK, PEI, etc.).

[0099] Example 8:

[0100] Once the parts have been built, when possible using the control sacrificial resins or the invention with a given polymer to be printed, the assembly is immersed in water at 60°C at a pH of 7 or 12 and the time taken for all the sacrificial material to dissolve is noted. When the test is deemed impossible, this means that the part to be built does not conform to the desired 3D digital model.

[0101] The results of dissolution and 3D printing tests are given in Table 2:

[0102] [Table 2]

[0103] Tl: Time in minutes, total dissolution at 60°C, water pH 7 T2: Time in minutes, total dissolution at 60°C, water pH 12

[0104] It is noted that whatever the polymer to be printed in Table 2, the sacrificial resins of the invention make it possible to support the polymer to be printed.

[0105] Example 9:

[0106] The mechanical properties of the sacrificial polymer of the invention 1 were evaluated with a tensile test, with or without addition of copolymer (II).

[0107] The measurement is made on a filament of length 14 cm and diameter 1.75 mm. The elongation at break is measured using equipment type "Zwick Roell Z005", with a 5 kN sensor, speed: 5 mm / min, distance between the jaws = 6 lmm.

[0108] The copolymers (II) tested are commercially available under the brand name Nanostrength ® with the references M52N and M65N. These copolymers conform in composition and molecular masses to the description given of the copolymers (II). They were added at a rate of 5 and 10% by mass. Table 3 shows the evaluations carried out:

[0109] [Table 3]

[0110] It is found that the addition of copolymer (II) improves the elongation at break on the one hand, and that this elongation is preserved after one month of storage on the other hand. The dissolution of a part of the materials of Example 9, with and without copolymer (II) was carried out at 60 °C and pH 12 and shows that it is only affected in small proportions when the copolymer (II) is present as shown in Table 4.

[0111] [Table 4]

[0112] The materials of examples 1 (I) and 9 (I+II) using 5% M52N were examined by DMA (dynamical mechanical analysis). Curve 1 shows that the rheological behaviors of the two materials are very similar.

Claims

DEMANDS 1. Use of at least one multiblock copolymer (I) as a sacrificial material in a 3D printing process for polymers with a Tg between 140 and 200 0 Choose from PEEK, PEKK, PEK, PEKEKK, PEEKK, PEKK, PE I, PAI, PSU, and PPS, at least one multiblock copolymer(s) (I) comprising at least one block consisting of i monomers M± linked statistically, i being an integer ranging from 2 to 5 inclusive, and at least one block consisting of j monomers M j statistically linked, j being an integer ranging from 2 to 5, inclusive, M± being selected from monomers A whose Tg of their homopolymers is less than 0°C and hydrophilic monomers B, the mass proportion of A ranging from 80 to 95% and the mass proportion of B ranging from 5 to 20%. M jbeing selected from monomers C whose Tg of their homopolymers is less than 0°C, monomers D whose Tg of their homopolymers is greater than 25°C and hydrophilic monomers E, the mass proportions of monomers C, D, E being respectively between 25-35%, 25-35%, 35-45%. 2 use according to claim 1 wherein at least one block copolymer (II) is present in mass proportions between 1 and 50% of the total weight (I) + (II).

3. Use according to claim 1 or 2 wherein the at least block copolymer (I) is a diblock copolymer or a triblock copolymer.

4. Use according to claim 3 wherein the block copolymer (I) is a diblock copolymer.

5. Use according to claim 4 wherein the diblock copolymer (I) has a mass proportion of blocks consisting of monomers of families A and B ranging from 5 to 40% (block 1) and a mass proportion of blocks consisting of monomers C, D, and E ranging from 50 to 90% (block 2).

6. Use according to claims 1 to 5 wherein the copolymer (II) has at least one block having a glass transition temperature below 0°C and at least one block having a glass transition temperature above 0°C.

7. Use according to claim 1 or 2 wherein the block copolymers are prepared by controlled radical polymerization.

8. Use according to claim 7 wherein the block copolymers are prepared by nitroxide-controlled radical polymerization.

9. Use according to claim 8 wherein the block copolymers are prepared by radical polymerization controlled by N-tert-Butyl-1-diethylphosphono-2,2-dimethylpropyl Nitroxide.

10. Use according to claim 8 wherein at least one block copolymer (I) is made up of blocks 1 incorporating butyl acrylate and acrylic acid and blocks 2 implementing butyl acrylate, styrene and methacrylic acid.

11. Use according to claim 1 wherein at least one block copolymer (I) has a molecular mass by weight between 80000 g / mol and 150000 g / mol.

12. Use according to claim 2 wherein the copolymer (II) has a molecular mass by weight between 50000 g / mol and 150000 g / mol.