Biodegradable and / or compostable bio-based powders for additive manufacturing and methods of use thereof

Abstract

The present invention is directed to certain biodegradable and / or compostable bio-based granular compositions for additive manufacturing, such as those comprising polyhydroxyalkanoate (PHA) powder, the granular composition and / or PHA powder having (a) a loose bulk density greater than 0.30 g / mL as determined by ASTM D1895-96, and (b) a sinterable range greater than 15 degrees Celsius. The present invention is also directed to certain methods of making the biodegradable and / or compostable bio-based granular compositions useful as powdered building materials for additive manufacturing processes. In addition, the present invention is directed to additive manufacturing processes utilizing the biodegradable and / or compostable bio-based granular compositions described elsewhere, as well as articles printed therefrom.

Description

[Technical field]

[0001] The present invention relates to certain biodegradable biologically derived powders for 3D printing, their use in 3D printing processes, and processes for their manufacture.Furthermore, the present invention relates to compositions containing certain biodegradable biologically derived powders, 3D printed articles produced therefrom, and methods for producing 3D printed articles using compositions containing the certain biodegradable biologically derived powders.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application No. 21179131.4, filed June 11, 2021, which is incorporated herein by reference. [Background technology]

[0003] A variety of additive manufacturing processes are known and used. One subset of these processes that utilize powder as the build medium is particularly useful for some end applications. These powder additive manufacturing processes include selective laser sintering (SLS), high speed sintering (HSS), or multi-jet fusion (MJF). Although there are known variations between these processes, all powder additive manufacturing methods generally involve the application of a high-density, high-energy radiation source, such as a laser, to selectively melt or fuse a portion of the particles into a desired shape. A control mechanism functions to direct both the path and intensity of the laser to fuse the powder, often in layers, within a specified boundary. Each layer, or "slice," represents a cross-section of the final component to be produced at a specified thickness. A machine control selectively operates to sinter successive layers of powder, producing a finished part that includes multiple slices sintered together. The machine control mechanism is preferably computer-directed and utilizes CAD files of various formats to determine the boundaries defined for each slice.

[0004] The part may be fabricated by depositing a first portion of a sinterable powder on a target surface of a part bed, scanning a laser directed over the target surface, and sintering a first layer of the first portion of the powder on the target surface to form a first slice. The powder is then sintered by operating a laser beam directed within a boundary defining the first slice with sufficient energy or fluence to sinter the powder. The first slice corresponds to a first cross-sectional area of ​​the part.

[0005] A second portion of powder may then be deposited on the part bed and the surface of the first sintered slice resting thereon, and a directed laser beam may be scanned over the powder covering the first sintered slice. A second layer of the second portion of powder is then sintered by operating the laser beam within a boundary, thereby defining a second slice. The sintered second slice is formed at a temperature sufficient to sinter it to the first slice, and the two slices are fused together into a single portion of the object to be built. Subsequent layers of powder are deposited on the previously sintered slice, each layer being sintered in turn to form additional slices.

[0006] A wide variety of materials can be used in powder-based additive manufacturing processes. Many thermoplastics, metals or ceramics are often used. Thermoplastic powders are preferred because they facilitate the creation of three-dimensional components with a wide variety of properties that may be suitable for many end uses. Preferred polymer powders include semi-crystalline thermoplastics because of their high sinterability compared to more crystalline thermoplastic materials.

[0007] Types of thermoplastic polymers that can be used in powder-based additive manufacturing processes include polyolefins, polyarylketones, polyamides, polyimides, polyesters, polyphenylene sulfides, polyarylketones, liquid crystal polymers, polyacetals, and fluorochemical resins.

[0008] Currently, the most common class of thermoplastics available for additive manufacturing includes polyamides. Two of the best known polyamides are poly(hexamethylene adipamide) (PA66 or nylon 6,6) and polycaprolactam (PA6 or nylon 6). Both PA6 (CAS number #25038-54-4) and PA66 (CAS number #32131-17-2) have excellent mechanical properties including high tensile strength, toughness, flexibility, elasticity, and low creep. They are easy to dye, have a low coefficient of friction (self-lubricating), and exhibit excellent abrasion resistance. Nylons typically have high melting and glass transition temperatures, which allows the solid polymers formed therefrom to have excellent mechanical properties even at high temperatures.

[0009] Additionally, certain polyesters are also known and described. Polyesters offer certain advantages that may be useful for some end uses. For example, nylons such as nylon 6,12 do not easily facilitate the incorporation of certain additives, such as flame retardants. Rather, such additives must be added to the various nylons via so-called "dry mixes." With polyesters, easier incorporation of such additives may be facilitated. Furthermore, polyesters generally have less water uptake than comparable polyamides. Furthermore, polyesters offer a sustainable advantage over other plastics. In addition to the fact that many polyesters are biodegradable or at least compostable, the means and infrastructure for recycling polyesters exceed those of virtually all other thermoplastic materials, thus providing an easier circular solution. Polyester powders for additive manufacturing are originally described in WO 2020 / 085912, assigned to DSM IP Assets BV.

[0010] Considering the increasing use of plastics worldwide, there is a strong and growing demand to provide more sustainable solutions. By way of preamble, additive manufacturing techniques facilitate this, as their relatively complex manufacturing methods provide a higher degree of customization than traditional manufacturing techniques, while producing less final waste. Furthermore, as described, some plastics are easily recyclable, which facilitates multiple functional uses from a given unit of starting material. Furthermore, more and more manufacturers are providing thermoplastic materials from bio-based sources, rather than petroleum-based sources. "Bio-based" means that the material is synthesized in whole or in part from a living source, such as a plant, animal, or microorganism.

[0011] In addition to the aforementioned approaches, it would also be desirable to increase the use of biodegradable or at least compostable plastics. As is widely known, most plastics in use today do not easily decompose or degrade at the end of their useful life, and they are typically disposed of either by incineration or by deposition in landfills. Unfortunately, much of the used plastic is increasingly entering the waterways and oceans of the planet. This accumulation of plastic is not only unsightly, but also has harmful effects on certain marine organisms. It is therefore particularly desirable to secure and utilize more plastics that are "biodegradable", i.e., plastics that can be easily broken down by living organisms into natural by-products such as water, carbon dioxide, and biomass.

[0012] Many types of biodegradable plastics are known. Biodegradable plastics can come from biological or petroleum-derived sources. From a sustainability perspective, biologically derived plastics are typically preferred. Biodegradable plastics include cellulosic plastics such as polyhydroxyalkanoates (PHAs), polylactic acids (PLAs), mixtures of starch with other biodegradable plasticizers, and certain cellulose esters.

[0013] There have been some attempts to provide specific biodegradable bio-based plastics for 3D printing. US Patent Application Publication No. 2019 / 375149A1, assigned to Tepha Inc., relates to a method for making objects by 3D printing poly-4-hydroxybutyrate (P4HB) and its copolymers. In one method, these objects are produced by processing continuously fused filaments using equipment and conditions that overcome the problem of insufficient filament feeding resulting from low filament softening temperature and thermal creep along the fed filament. A method is disclosed that uses an equipment including a heat sink, a melt tube, a heating block and a nozzle, and a transition zone between the heat sink and the heating block, where the melt tube extends through the heat sink, the transition zone and the heating block to the nozzle. 3D objects are also printed by fused pellet deposition (FPD), melt extrusion deposition (MED), selective laser melting (SLM), printing of slurries and solutions using a coagulation bath, and printing using binding solutions and polymer granules.

[0014] Brazilian Patent Application Publication No. BRPI1003549A2, assigned to Ct de Tecnologia Da Informacco Renato Archer, describes a solution to provide a dispersible poly(3-hydroxybutyrate) (P3HB) for implant scaffolding and / or prototypes.

[0015] WO 2019 / 043137A1, assigned to Evonik Rohm Gmbh, is directed to biocompatible polymer powders for use in 3D printing applications, with examples based on polylactic acid (PLLA), poylactic acid polycaprolactone (PCL), and polycaprolactone (PCL). More specifically, the 3D printing process enables tool-free manufacturing of medical devices, especially in the implantable or regenerative space. Its flowability and other processing properties allegedly make it eligible for use in selective laser sintering, but it would also be suitable for other powder 3D printing techniques.

[0016] It is known that most of the known biodegradable bio-based polymers, such as PHA and PHB, crystallize relatively quickly from the melt compared to other known polymers, such as polyamides. This characteristic can be advantageous in injection molding applications due to the resulting shorter cycle times, lower molding temperatures, and excellent dimensional stability, but makes processability in laser sintering applications more difficult. This is because the viable operating window of the additive manufacturing process correlates with the difference between melting and crystallization of the particular material processed. Thus, a small delta between melting and crystallization causes a small viable operating window, which makes an effective additive manufacturing process difficult or potentially impossible to achieve. In the SLS process, for example, a new layer of cooler powder is deposited on a warmer recently sintered layer. If the difference between the melting and crystallization temperatures of the sintered material is too narrow, the cooler new powder can cause a temperature drop to a point below the crystallization temperature of that material. This can result in deformation, curvature, or warping of the rapidly cooled part, and can also result in parts without proper density or part uniformity.

[0017] Furthermore, due to the inherent limitations of the three-dimensional printing process, a large portion of the polymer powder is not transformed into the desired shape. This remaining polymer powder (including waste, failed shapes, agglomerated particles, and flowed powder) is typically exposed to high temperatures, oxygen, contaminants, and / or processing fluids for extended periods of time. As a result of such exposure, the powder can, for example, suffer adverse effects on its melting properties. Thus, even after regrind, the material, especially those that begin with narrow sinterable regions, cannot be reliably used again in MJF, HSS, or SLS printing processes.

[0018] Existing PHAs for additive manufacturing also do not offer sufficient processability / recyclability because they do not flow properly due to particle size variations and / or are not formulated to provide sufficient difference between melting and crystallization temperatures.

[0019] It is desirable to provide powders for additive manufacturing processes that allow for the exploitation of the advantages of biodegradable (or compostable) biologically derived materials such as PHA. Alternatively, or additionally, it would be beneficial to provide such powders with a higher and wider "sinterability window", which is the difference between the melting onset temperature of a polymer and its crystallization onset temperature, to improve suitability for use in 3D printing processes.

[0020] Thus, despite the aforementioned attempts, to date there exists an unmet need to provide certain biodegradable (or compostable), biologically derived polymer powders, and in particular certain polyhydroxyalkanoates, for use in additive manufacturing applications that offer improved utility and / or performance, such as through improved printability, flowability, and / or mechanical properties of objects made therefrom. Summary of the Invention

[0021] A first aspect of the present invention is directed to a method for producing a granular composition useful as a powder building material for additive manufacturing sintering processes, the method comprising the steps of: (a) providing a starting material comprising a homopolymer or copolymer of 3-hydroxybutyric acid; (b) optionally consolidating the starting material at a consolidation pressure of >40 kN, thereby obtaining a consolidated material; (c) heating the starting material of step (a) or the consolidated material of step (b) to a temperature sufficient to prevent sticking of the starting material or the consolidated material, thereby obtaining an annealed material; and (d) grinding the annealed material of step (c) to a powder having a D50 particle size value of 20 to 100 microns, thereby obtaining a ground material.

[0022] A second aspect of the present invention is a granular composition for additive manufacturing. According to a preferred embodiment of the second aspect, the granular composition comprises, consists of, or consists essentially of a polyhydroxyalkanoate (PHA) powder, the granular composition and / or the PHA powder having (i) a loose bulk density, as determined by ASTM D1895-96, of more than 0.30 g / mL, and (ii) a sinterable region above 15 degrees Celsius, the sinterable region being greater than ... i,m From T f,c is determined by subtracting

[0023] According to a further preferred embodiment of the second aspect, the granular composition is used as a building material for an additive manufacturing sintering process and is obtainable by a method according to any of the embodiments of the first aspect.

[0024] A third aspect of the invention comprises an additive manufacturing process comprising any of the granular compositions and / or PHA powders according to any of the embodiments of the second aspect of the invention, and / or any of the granular compositions made by the process described in any of the embodiments of the first aspect.

[0025] According to a preferred embodiment of the third aspect, the process comprises the steps of: (a) providing a layer of a granular composition for additive manufacturing comprising a PHA powder according to any of the embodiments of the second aspect; (b) optionally selectively depositing a liquid composition onto the layer of granular composition, where at least one of the granular composition or the liquid composition comprises a fusing agent; (c) applying electromagnetic radiation to either (i) specific locations on the layer of granular composition or (ii) locations of the liquid composition selectively deposited on the granular composition, where the granular composition undergoes melting to form a fused portion at least in a portion of the locations where the electromagnetic radiation and / or the liquid composition is applied, according to computer data corresponding to a portion of the three-dimensional object to be formed; and (d) repeating steps (a), optionally steps (b), and (c) multiple times to form a fused three-dimensional object.

[0026] A fourth aspect of the invention is an article printed via any of the processes described in the third aspect. The article printed according to the fourth aspect is preferably derived from a granular composition according to any of the embodiments of the second aspect, which granular composition preferably originates via any of the embodiments described according to the first aspect of the invention. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 shows the DSC curves of sample materials, and is further shown to facilitate the determination of the various melting and crystallization points of particular materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The present invention is directed to providing biodegradable and / or compostable biological powders with enhanced suitability for 3D printing. Described herein are methods for making such powders as build materials for additive manufacturing sintering processes, build materials produced therefrom, methods for using the build materials in additive manufacturing processes, and articles printed therefrom. Also described herein are specific granular compositions for use in additive manufacturing processes that include polyhydroxyalkanoate (PHA) powders, which compositions and / or powders are configured to have certain novel characteristics that make them particularly suitable for use in 3D printing processes. Also described are methods for performing additive manufacturing processes, which include utilizing granular compositions that include PHA powders, and articles produced therefrom.

[0029] A first aspect of the invention is a method for producing a granular composition suitable as a powder building material for an additive manufacturing sintering process, comprising the steps of: (a) providing a starting material comprising a homopolymer or copolymer of 3-hydroxybutyric acid; (b) optionally consolidating the starting material at a consolidation pressure of >40 kN, thereby obtaining a consolidated material; (c) heating the starting material of step (a) or the consolidated material of step (b) to a temperature sufficient to prevent sticking of the starting material or consolidated material, thereby obtaining an annealed material; (d) grinding the annealed material of step (c) into a powder having a D50 particle size value of 20-100 microns, thereby obtaining a ground material.

[0030] In an embodiment of the first aspect, a starting material is provided. The starting material comprises a homopolymer or copolymer of 3-hydroxybutyric acid. 3-hydroxybutyric acid, also known as β-hydroxybutyric acid, is an organic compound and a beta hydroxy acid with the chemical formula CH3CH(OH)CH2CO2H, whose conjugate base is β-hydroxybutyrate, also known as 3-hydroxybutyrate. β-hydroxybutyric acid is a chiral compound with two enantiomers, D-β-hydroxybutyric acid and L-β-hydroxybutyric acid. Its oxidized polymeric derivatives occur widely in nature. 3-hydroxybutyric acid is a precursor of poly(3-hydroxybutyrate) (P3HB), a biodegradable polyester. The chemical structure of P3HB is shown below. [ka]

[0031] In a preferred embodiment, the starting material comprises, consists of, or consists essentially of P3HB polymer. At standard temperature and pressure, the P3HB polymer may be in any suitable form, such as powder, flakes, or granules. Of these, powders are preferred.

[0032] In various embodiments, the starting material comprises a (co)polymer of 3-hydroxybutyric acid and an additional acid. The additional acid may be of any suitable type that ensures compatibility and biodegradability of the resulting polymer, but particularly preferred additional acids include 3-hydroxyhexanoic acid and 3-hydroxyvaleric acid. As used herein, the copolymer of 3-hydroxybutyric acid and 3-hydroxyhexanoic acid is referred to as "PHBH", while the copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid is referred to as "PHBV". Furthermore, as used herein, the general name of the homopolymer of 3-hydroxybutyric acid or the copolymer of 3-hydroxybutyric acid and any additional acid is referred to herein according to the general name "PHBx".

[0033] When used, the comonomers may be incorporated in any amounts relative to one another as desired, such as in amounts of 1 to 50 mole percent, preferably 1 to 15 mole percent.

[0034] P3HB occurs naturally, such as through the bacterium alcaligenes eutrophus, but it can also be produced synthetically - along with other PHBx polymers. A known general such process for the production of PHBx involves the fermentation of suitable bacteria in the presence of sucrose to obtain a mixture. The resulting PHBx can then be isolated from the bacteria. At this stage, the PHBx has a typical particle size on the order of 0.25 to 1 micron. Most commercial processes then have an aggregation step, which results in the polymer having an average particle size of 1 to 200 microns. Other processes for the synthesis of powders, flakes or granules of PHBx will be understood by those skilled in the art to which the present invention pertains.

[0035] The starting material according to various embodiments of the first aspect is subjected to various processes to obtain a powdered building material suitable for an additive manufacturing sintering process. According to certain embodiments, the starting material is consolidated. The inventors have found that existing PHBx powders known so far are not sufficient to serve as a building material suitable for an additive manufacturing process. The inventors have found that most are friable powders that do not provide optimal flowability (or even sufficient flowability) and, even if they allow the construction of printed parts, they may not allow the creation of printed objects with the necessary dimensional accuracy and precision required for many end uses. Moreover, such powders do not facilitate the creation of objects with sufficient mechanical properties. As such, they can only be used in limited applications, such as bone or tissue scaffolds.

[0036] Thus, in some embodiments according to the first aspect, the starting material is first subjected to a compaction step. In preferred embodiments, compaction is carried out by any suitable apparatus for compacting such materials, including, for example, a Bepex Labor Kompaktor. The force and / or pressure applied to the starting material may vary as desired, but in preferred embodiments, the starting material is compacted with a specific linear force that is at least 40 kilonewtons per centimeter (kN / cm), more preferably at least 80 kN / cm, more preferably at least 100 kN / cm, or between 40 and 400 kN / cm, or between 80 and 300 kN / cm, or between 100 and 25 kN / cm. Such compaction may be achieved between two rollers. In another embodiment, compaction is carried out with a specific linear force of at least 5 kN / cm for the material. 2 More preferably, 25 kN / cm 2 More preferably, more than 40 kN / cm 2 or 5~400kN / cm 2 , or 25~300kN / cm 2 , or 40~200kN / cm 2 The inventors have surprisingly discovered that the beneficial effects of this consolidation step remain in the starting material even after subsequent downstream processing described elsewhere herein, such that the resulting processed material retains improved suitability for use in additive manufacturing applications.

[0037] According to some embodiments of the first aspect, the consolidated material from the consolidation step is then heated to produce an annealed material. In the heating step, the consolidated material is preferably heated to a temperature sufficient to prevent sticking of the consolidated material. The heating process preferably includes annealing in the sense that the consolidated material is heated to a temperature below its glass transition temperature or peak melting temperature for a moderate period of time and then cooled again to reduce its internal stresses.

[0038] The method of heating will vary depending on several factors that will be understood by those skilled in the art to which the present invention pertains, such as, but not limited to, the desired amount of material to be heat treated. General common techniques include batch heating and continuous heating. Batch heating typically involves forced convection in an oven, although for laboratory-scale quantities, other methods can be used, such as inserting a flask containing the material into a hot oil bath or tumble dryer under vacuum while purging with inert gas. Continuous heating, on the other hand, typically involves passing the material along a conveyor into a heated tube or chamber. This method is more suitable for industrial-scale heating processes, as it allows less restriction of airflow. Regardless of whether a batch or continuous heating process is utilized, other heating methods, such as through the application of infrared radiation, may be employed as an alternative to the aforementioned convection heating.

[0039] Regardless of the overall technique, the process typically involves heating the material (i) to a desired temperature, (ii) at a controlled rate, (iii) maintaining this desired temperature for a specified period of time, and then (iv) cooling the material at a controlled rate to (v) a final temperature. Any of (i)-(v) can be varied as desired, as will be appreciated by those skilled in the art, with it being further understood that different PHBx polymers will require different conditions since they will have disparate material properties.

[0040] However, in various embodiments, (i) is selected to be at most 120° C., or 130° C., or 135° C., or 140° C., or 150° C., or 160° C., or 170° C. The final desired temperature (i) should be selected so as not to exceed the peak melting temperature of the material being utilized, but not to exceed the melting point onset temperature (T m , onset) for at least a short period of time. In other embodiments, (i) can vary depending on the material, such as from 100 to 200°C, or from 120 to 180°C, or from 130 to 160°C.

[0041] Regardless of the final heating temperature, various (ii) heating rates may be selected, for example 1° C. / hr to 100° C. / hr, or 2° C. / hr to 25° C. / hr, more preferably 5° C. / hr to 10° C. / hr, although other rates may be suitably used. The heating rate of (ii) is not necessarily as critical as (i) or (iii), provided that the material is heated uniformly and does not locally exceed the peak melting temperature. It will, of course, be understood that rapid heating is desirable to minimize overall processing time.

[0042] It is further understood that heating can occur continuously or in a stepwise process, i.e. the material can be heated to a particular intermediate value below the final desired peak temperature (i), maintained for a specified period of time, and then further increased as required. This stepwise process can occur in the presence of two or more so-called intermediate desired temperatures, with one, two, or more than two intermediate hold times in between.

[0043] Once the final desired temperature (i) is achieved, the material may be maintained at such temperature for any specified length of time (iii), in one embodiment, (iii) is from 1 minute to 4 hours, or from 30 minutes to 2 hours.

[0044] Finally, the material is preferably cooled from the desired temperature to return to an equilibrium temperature for use in further processing of the material. It is understood that this cooling can occur at any rate (iv), and that the cooling can be in a continuous or stepwise manner and can be under application of a N2 atmosphere and / or reduced pressure. Meanwhile, the final equilibrium temperature (v) is preferably at or near ambient or room temperature.

[0045] In one embodiment, the method according to the first aspect of the invention comprises, after the heating step, an optional step of grinding the annealed material to form a ground material, inter alia having a desired average particle size or particle size distribution. This step is necessary if the starting material is in the form of flakes, granules or another powder having an average particle size larger than the desired final average particle size of the final build material for a given additive manufacturing process.

[0046] In any event, this annealed material may be subjected to a grinding or micronization process to provide a particle size suitable for the intended printing process. Grinding may be performed at or near room temperature (e.g., 10-30°C), but may be lower in other methods such as cryogenic grinding. In cryogenic grinding, or cryo-grinding, the polymer is cooled by liquid nitrogen (alternatives to N2 include solid or liquid carbon dioxide) to prevent softening and clogging of the equipment during grinding. Physical sorting or sieving may then be performed to keep the particles below a desired maximum size.

[0047] Other well-known grinding techniques include jet milling and mechanical grinding. Jet milling processes use, for example, high-velocity jets of compressed air or inert gas to pulverize materials by colliding particles against each other. Jet mills can be designed or used to output particles below a certain size, and continuously grind particles above that size, resulting in a narrow particle size distribution of the resulting product. Particles exiting the mill can be separated from the gas stream by cyclone separation.

[0048] Milling techniques, particularly mechanical milling, may be carried out in a pinned disk mill, a fluidized bed opposed jet mill, or a baffle plate impact mill. Regardless of the milling technique and equipment used (all of which are well known in the art to which the present invention applies), the process should be carried out so that the resulting particle size distribution has a median particle size D50 in the range of 1-650 microns, or more preferably 1-400 microns, or, for example, 10-200 microns, 20-100 microns, or 40-50 microns. The median particle size D50 may be determined via a variety of methods, including TEM, SEM, dynamic light scattering, and static light scattering. Non-limiting examples of suitable equipment for measuring particle size include the LB-550 equipment available from Horiba Instruments, Inc., which measures particle size by dynamic light scattering. A preferred method for determining the D50 median particle size is by laser diffraction particle size analysis according to ISO 13320-1.

[0049] In a preferred embodiment, the annealed powder is milled to a particle size distribution having a D50 particle size in the range of 20-100 microns, or 30-90 microns, or 30-80 microns, or 40-90 microns, or 40-80 microns, or 40-50 microns. A narrow particle size distribution with average particles of the recited sizes is desirable as it tends to improve the flowability of the final powder made therefrom. This ensures good processability and reduced agglomeration when the powder is used in powder-based additive manufacturing processes such as multi-jet fusion or selective laser sintering.

[0050] In a preferred embodiment, the milling step comprises a jet milling or mechanical milling process, wherein the jet milling or mechanical milling process is carried out at a temperature of 15-35°C, or 15-30°C.

[0051] After grinding, the particles can be subjected to post-treatment in a mixer with high shear forces, preferably below the melting point onset temperature or glass transition temperature of the polymer, to round the particles. Other further treatments of the particles to round the particles and improve flowability can include a fractionation step via sieving, sieving, or the addition of powder flow aids. Rounding the particles is advantageous because it promotes the creation of particles with increased sphericity. This then has a positive effect on the flow potential of the powder to maximize its suitability in 3D printing applications.

[0052] According to other embodiments of the first aspect, the consolidation step may not be required. In addition to these material providing, consolidating, heating, and grinding steps, additional steps may also be inserted. These steps may be included before, between, or after any of the aforementioned steps as desired, and they may be performed once or more than once.

[0053] In one embodiment, the process according to the first aspect also involves adding one or more compositional additives to the starting material, the compacted material, the annealed material, and / or the ground material. When an additive is included, the granular composition will contain both the additive component as well as the product of the processed starting material (such as a homopolymer or copolymer of 3-hydroxybutyric acid).

[0054] Such additives may be any suitable additive used in 3D printing, including, but not limited to, flame retardants, flow aids, fillers, pigments, and stabilizers. Suitable flow aids include fumed silica, precipitated silica. Suitable fillers include glass particles and glass fibers (having lengths up to, but preferably less than, 100 microns), glass beads, metal particles, and ceramic particles. Suitable pigments include titanium dioxide, rutile-based particles, anatase-based particles, carbon black particles, carbon fibers, and stabilizers such as thermal stabilizers and UV stabilizers. If used, in one embodiment, one or more flow aids may be included in an amount of 0.05 to 20% by weight of the total granular composition.

[0055] The introduction of additives can occur before the consolidation step, between the consolidation and heating steps, between the heating and grinding steps, or after the grinding step. The additives can be included in the dry mix or can be blended into the starting material, the consolidated material, the annealed material, and / or the ground material as required.

[0056] Various additional additives are known that can be incorporated into the granular composition according to the invention at one or more of the steps of the aforementioned process. Suitable additives for the granular composition for additive manufacturing according to various embodiments of the invention include, for example, flow aids (other than the monomeric, oligomeric or polymeric flow aids described elsewhere herein), fillers (chopped or crushed glass fibers, chopped or crushed carbon fibers, nanofillers, dispersed reinforcing materials such as clay, wollastonite and mica, and continuous reinforcing materials), pigments, processing aids (such as release agents), leveling agents, degassing agents, stabilizers (such as antioxidants and UV stabilizers), plasticizers, impact modifiers (core-shell rubber particles), and carrier polymers.

[0057] Other examples of fillers that are known and commonly used in thermoplastic resin compositions include inorganic fillers such as clay, mica, talc, and glass spheres or beads. Reinforcing fibers are, for example, glass fibers. The advantage of resin compositions containing glass fibers is their high strength and stiffness, especially at high temperatures, which allows them to be used at temperatures up to close to the melting point of the polymer in the relevant composition.

[0058] Inorganic materials are particularly suitable as fillers because they tend to impart water resistance, heat resistance, and robust mechanical properties to the composition. In one embodiment of the present invention, the filler is inorganic and includes ceramics such as silica (SiO2) nanoparticles, i.e., particles with an average particle size of 1 nanometer (nm) to 999 nm or 5 nm to 800 nm, or microparticles, i.e., particles with an average particle size of 1 micrometer (μm) to 999 μm or 1 to 100 μm. The average particle size can be measured using various techniques such as scanning electron microscopy or laser diffraction particle size analysis according to ISO 13320-1. For further examples of silica nanoparticles, see U.S. Pat. No. 6,013,714.

[0059] In other embodiments of the present invention, alternative inorganic filler materials may be used, such as those containing glass or metal particles.Specific non-limiting examples of such materials include glass powder, alumina, alumina hydrate, magnesium oxide, magnesium hydroxide, barium sulfate, calcium sulfate, calcium carbonate, magnesium carbonate, silicate minerals, diatomaceous earth, silica sand, silica powder, titanium oxide, aluminum powder, bronze, zinc powder, copper powder, lead powder, gold powder, silver dust, glass fiber, cellulose fiber, cellulose nanocrystals, potassium titanate whisker, carbon whisker, sapphire whisker, verification rear whisker, boron carbide whisker, silicon carbide whisker, and silicon nitride whisker.

[0060] However, in one embodiment, the granular composition according to the invention is substantially free of any fillers, which may be beneficial because it ensures improved workability (i.e. flowability, surface finish) of the sintered product formed therefrom.

[0061] Suitable impact modifiers are rubbery polymers that contain polar monomers such as olefins, but also polar or reactive monomers such as acrylates and epoxides, acid- or anhydride-containing monomers, among others. Examples include copolymers of ethylene and (meth)acrylic acid, or ethylene / propylene copolymers functionalized with anhydride groups. The advantage of impact modifiers is that they not only improve the impact strength of the resin composition, but also contribute to an increase in viscosity. Suitable impact modifiers are, for example, maleic anhydride-functionalized polyolefins.

[0062] Colorants such as pigments or dyes may also be optionally included in various embodiments. Colorants may be, for example, carbon black or nigrosine. EP2935430 describes a variety of other common pigments that may be suitably used herein, including, for example, titanium dioxide in one or more of the three crystal forms (rutile, anatase, and titanyl), ultramarine, iron oxide, bismuth vanadate, metallic pigments such as aluminum flakes, and pearlescent pigments such as mica, as well as organic pigments such as phthalocyanines, perylenes, azo compounds, isoindolines, quinophthalones, diketopyrrolopyrroles, quinacridones, dioxazines, and indanthrones.

[0063] The granular composition may further comprise one or more stabilizers. The presence of a stabilizer is optional. Stabilizers are known per se and are intended to counteract deterioration as a result of the effects formed, for example, by heat, light and radicals. Known stabilizers that may be applied to the composition include, for example, hindered amine stabilizers, hindered phenols, phenolic antioxidants, copper salts and halides, preferably bromides and iodides, and mixtures of copper salts and halides, such as copper iodide / potassium iodide compositions, as well as phosphites, phosphonites, thioethers, substituted reorcinols, salicylates, benzotriazoles, hindered benzoates, and benzophenones. Preferably, the stabilizer is selected from the group consisting of inorganic, hindered phenolic oxidizers, hindered amine stabilizers, and combinations thereof. More preferably, the stabilizer is a combination of inorganic stabilizers, phenolic antioxidants, and hindered amines. In one embodiment, when the composition includes a stabilizer component, such component is present in an amount of from about 0.05% to about 2.0% by weight, or from about 0.1 to 1.5% by weight, or from 0.3% to 1.2% by weight, based on the total composition.

[0064] In one embodiment, the granular composition also contains one or more lubricants. Such substances include long chain fatty acids, especially stearic acid or behenic acid, their salts, especially Ca stearate or Zn stearate, and their ester or amide derivatives, especially ethylene-bis-stearylamide, montan wax, and low molecular weight polyethylene or polypropylene waxes. In one embodiment, suitable lubricants include esters or amides of saturated or unsaturated aliphatic carboxylic acids of 8 to 40 carbon atoms with saturated aliphatic alcohols or amines of 2 to 40 carbon atoms, and metal salts of saturated or unsaturated aliphatic carboxylic acids of 8 to 40 carbon atoms used with ethylene bis-stearylamide, and calcium stearate.

[0065] The foregoing list of additives is not intended to be limiting, and any other suitable additives may be employed as would be normally understood by one skilled in the art to which the present invention applies. Further such examples include UV stabilizers, gamma radiation stabilizers, hydrolysis stabilizers, heat stabilizers, antistatic agents, emulsifiers, nucleating agents, drip agents (such as polytetrafluoroethylene or polyvinylpyrrolidone), and plasticizers.

[0066] The additives described herein, when included, may be used alone or in combination of two or more, and may be blended, molecularly mixed, or dry mixed with a granular composition suitable as a powder modeling material for additive manufacturing according to the present invention. When any additives are present, the granular composition may contain 0.001% to 80% by weight, or 0.1% to 60% by weight, or 0.5% to 25% by weight of the additive, based on the total weight of the granular composition.

[0067] According to various non-limiting embodiments, the material may also be subjected to a screening step. The screening step may be performed once or multiple times to select a subset of particles, flakes or granules contained in the material for further manipulation or use. This is typically accomplished through sieving or screening, and the screening and / or screening device may be selected with one or more sieves or sieves to screen out particles above and / or below any specified size. In one embodiment, the starting material is sieved to ensure that particles below 30 microns and above 100 microns are not retained to any substantial extent. The screening step may be performed at any point or points along the process, but is usually performed before the consolidation step. Alternatively, it may be performed before the heating step, after the heating step, before the grinding step, after the grinding step, or not at all. In alternative embodiments, the screening step is performed before or after multiple steps of the process, or even before or after each step of the process. The screening step is preferably performed as a final step to ensure that the final granular composition is optimized for suitability as a powder build material for use in an additive manufacturing process.

[0068] According to another embodiment, the PHA of the PHA powder has a weight average molecular weight Mw of 200000-1000000 g / mol, determined by gel permeation chromatography on polymethylmethacrylate with hexafluoroisopropanol (HFIP) as eluent. The HFIP eluent may also contain potassium trifluoroacetate, for example in an amount of 0.1% by weight. The GPC analysis may be carried out at a temperature above room temperature, for example at 35° C. The Mw is preferably 350000-900000 g / mol, and more preferably 380000-800000 g / mol. Such high molecular weights in polymers can be obtained via biotechnology processes.

[0069] A second aspect of the invention is a granular composition for additive manufacturing, preferably obtained by the above-mentioned method according to any of the embodiments of the first aspect of the invention. According to a preferred embodiment of the second aspect, the granular composition for additive manufacturing has a loose bulk density above a certain threshold and / or a sinterable domain above a certain threshold. A particularly preferred embodiment according to the second aspect is directed to a granular composition for additive manufacturing comprising, consisting of or essentially consisting of a polyhydroxyalkanoate (PHA) powder, wherein the granular composition and / or the PHA powder are (i) a loose bulk density, as determined by ASTM D1895-96, greater than 0.30 g / mL; and (ii) a sinterability range above 15 degrees Celsius, the sinterability range being T according to ISO 11357-1 (2009) i,m From T f,c The sinterable region is determined by subtracting the value of

[0070] The useful PHAs according to the second embodiment are polyesters that can occur in nature by a large number of microorganisms, including through bacterial fermentation of sugars or lipids. This class of biodegradable biologically derived polymers involves the inclusion of over 150 different monomers that can be combined to obtain materials with a wide range of properties. These materials are described in Biopolymers, Volume 4 (Polyesters III-Applications and Commercial Products); Doi, Yoshiharu; Steinbuchel, Alexander (2002); Weinheim, Germany: Wiley-VCH (ISBN 978-3-527-30225-3).

[0071] PHA polymers encompass many more species than the PHBx polymers described elsewhere herein below, but a preferred subset of PHAs includes species from the PHBx family. Particularly preferred PHAs useful as powders include poly-3-hydroxybutyrate (P3HB), poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO), polyhydroxydecanoate (PHD), polyhydroxydodecanoate (PHDD), or copolymers thereof. Thus, in one embodiment, the PHA powder comprises, consists of, or consists essentially of P3HB, P4HB, PHV, PHH, PHO, PHD, PHDD, or any combination thereof. In particularly preferred embodiments, the PHA powder comprises, consists of, or consists essentially of P3HB.

[0072] The PHA powders useful in the second aspect of the present invention can be provided through various processes and / or methods, including non-limiting examples such as the general process for the synthesis of PHBx polymers set forth above, below, and through the methods described in Biopolymers, to name a few.

[0073] The granular compositions according to the second aspect may be provided alone or as a kit of materials and they may comprise one or more additives. In an embodiment, the PHA powder is dry mixed with one or more additives to form the granular composition. In another embodiment, the PHA powder and / or the granular composition is a polymeric compound powder containing other biopolymers (PLA, cellulose or starch based) or biomonomers. The granular composition itself may further comprise one or more additives, more than the PHA powder, to obtain a granular composition for additive manufacturing, as specified below and elsewhere in this specification, with respect to the first aspect of the invention. For the avoidance of doubt, such additives as described in relation to the first aspect of the invention may be used in the same amounts as described with respect to the granular composition according to the second aspect.

[0074] Additives including flame retardants, flow aids, fillers, pigments, stabilizers, and glass fillers are common and may be used alone or in any combination as appropriate for the desired end use of the three-dimensional parts made therefrom. Such additives may be similarly incorporated or added at any stage or step, and in any manner, described elsewhere herein, as will be understood by those of skill in the art.

[0075] In addition to the additives mentioned elsewhere herein, the non-PHA portion of the granular composition may comprise, consist of, or consist essentially of other granular polymers. In a preferred embodiment, the non-PHA portion of the granular composition comprises, consists of, or consists essentially of polyester powders, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or copolymers thereof. Considering that PHA is also a polyester, in one embodiment the granular composition comprises, consists of, or consists essentially of polyester. Of course, in the absence of additives or other polymers, the granular composition according to the second aspect may comprise, consist of, or consist essentially of PHA powder. Thus, in another non-limiting embodiment, the polyester content in the granular composition consists essentially of PHA, PHBx, PHBH, or P3HB, or a combination thereof, or consists essentially of PHA, PHBx, PHBH, or P3HB, or a combination thereof.

[0076] As described, the granular composition and / or PHA powder is configured to have a certain density value. The inventors have found that such granular composition and / or powder will not provide sufficient printability unless it has the required density value. Most available powders have a density that is too low to be suitable. The density of such materials can be increased through a number of means, including the methods described elsewhere herein, preferably with respect to the consolidation step of the first aspect of the present invention.

[0077] The density of granular materials or powders can be measured in a number of different ways, but "apparent density" (also known as "free bulk density" (FBD) and referred to as such herein) and "tapped bulk density" (TBD) are two commonly used methods. FBD is a measure of the density of an unconsolidated powder sample and depends on both the intrinsic density of each particle as well as the arrangement between the particles. TBD, on the other hand, depends only on measurements after mechanically compacting a container containing the powder sample to the point where no further specified volume change is observed. A non-limiting method for determining FBD and TBD is ASTM D1895-96(2010), Test Method A.

[0078] Thus, in one embodiment, the FBD of the granular composition is greater than 0.35 g / ml, or greater than 0.40 g / ml, or between 0.30 and 0.9 g / ml, or between 0.30 and 0.6 g / ml, or between 0.30 and 0.50 g / ml, or between 0.40 and 0.9 g / ml, or between 0.40 and 0.8 g / ml, or between 0.40 and 0.7 g / ml, or between 0.40 and 0.60 g / ml, or between 0.40 and 0.50 g / ml. In other embodiments, the TBD of the granular composition is greater than 0.3 g / ml, or greater than 0.4 g / ml, or greater than 0.5 g / ml, or between 0.3 and 0.9 g / ml, or between 0.3 and 0.75 g / ml, or between 0.3 and 0.65 g / ml, or between 0.4 and 0.9 g / ml, or between 0.4 and 0.75 g / ml, or between 0.4 and 0.65 g / ml, or between 0.5 and 0.9 g / ml, or between 0.5 and 0.75 g / ml, or between 0.5 and 0.65 g / ml.

[0079] However, due to the inherent properties of certain additives and the amounts used, the density of the granular composition may vary and it may be more appropriate to measure the density only for the PHA powder component alone. Thus, in another embodiment, the FBD of the PHA powder is greater than 0.40 g / ml, or between 0.30 and 0.6 g / ml, or between 0.30 and 0.50 g / ml, or between 0.40 and 0.7 g / ml, or between 0.40 and 0.60 g / ml, or between 0.40 and 0.50 g / ml. In still other embodiments, the TBD of the PHA powder is greater than 0.3 g / ml, or greater than 0.4 g / ml, or greater than 0.5 g / ml, or between 0.3 and 0.9 g / ml, or between 0.3 and 0.75 g / ml, or between 0.3 and 0.65 g / ml, or between 0.4 and 0.9 g / ml, or between 0.4 and 0.75 g / ml, or between 0.4 and 0.65 g / ml, or between 0.5 and 0.9 g / ml, or between 0.5 and 0.75 g / ml, or between 0.5 and 0.65 g / ml.

[0080] On the other hand, if the density value is too high, the PHA powder will not have sufficient fluidity. Therefore, the FBD and / or TBD of the granular composition and / or the PHA powder is preferably less than 100 g / mL, more preferably less than 5 g / mL, or even less than 1 g / mL.

[0081] In addition to having the required density properties, in order to optimize suitability for use in additive manufacturing processes, the granular composition and / or PHA according to the second aspect of the invention also preferably have specified thermal properties. Such properties of polymer powders are usually described as the crystallization temperature (T c ) and melting point temperature (T m However, the inventors believe that a more important determining factor for evaluating its potential suitability for use in an additive manufacturing process is the powder's melting onset temperature (T m , onset) and crystallization onset temperature (T c , onset), which is mathematically defined herein as ΔT=(T m ,onset-T cThis is because the difference between these values, expressed as ΔT, onset, represents the temperature range within which the inventors estimate that the powder will be suitable for use in an additive manufacturing process. The ΔT of a powder, synonymously referred to herein as its "sinterability region", must be maximized to ensure that the powder will behave in a consistent manner in the additive manufacturing process in which it is used, even with natural temperature fluctuations. Powders of the present invention may exhibit a wider sinterability region than conventional powders of the same type. To accomplish this, powders of the present invention also have a higher ΔT m , onset value may also be present. Alternatively, a lower T c , onset values. Furthermore, they may exhibit higher T m ,onset value and lower T c , onset values ​​may be present simultaneously.

[0082] As used throughout this specification, unless otherwise specified, T m The value of onset is T c ,onset, are determined by the method specified in ISO 11357-1(2009). i,m It is called T m The onset is measured by determining the first detectable deviation (e.g., 0.1 mW) of the melting peak curve from the extrapolated onset baseline when the material being evaluated is heated at a constant heating rate of 10°C / min during the first heating cycle as evidenced by differential scanning calorimetry (DSC). c ,onset is determined in a relevant manner according to ISO 11357-1, and it is f,c This is referred to as the last detectable deviation of the curve from the extrapolated end baseline of the crystallization peak curve of the material being evaluated.

[0083] A hypothetical DSC curve with associated points as specified in ISO 11357-1 (2009) is shown in Figure 1. With reference to Figure 1, a thermograph shows the measured heat flow (also called dQ / dt) on the y-axis for a sample being evaluated as a function of temperature on the x-axis. Various points along this curve are designated with names that will be understood by one of ordinary skill in the art with reference to ISO 11357-1.

[0084] As used herein, the sinterable domain of a material is defined as T f,c (Equivalently, in this specification, m , onset) from the temperature value determined at i,m (Equivalently, in this specification, c , onset) is determined by subtracting the value of the temperature determined at

[0085] Thus, the granular composition and / or PHA powder of the second embodiment has a specified sinterable region. As mentioned above, by maintaining a higher sinterable region than known similar granular compositions and / or PHA powders for additive manufacturing, the powder of the present invention facilitates improved usability in additive manufacturing processes such as selective laser sintering or multi-jet fusion processes with which such particles are associated. Furthermore, as described, powders with a wider sinterable region will more easily provide for the manufacture of three-dimensional components with higher dimensional accuracy, less warping, curvature, and deformation, and improved structure and homogeneity. Characterizing the "sinterable region" as defined herein is believed to be a better proxy for real-world utility than other methods of obtaining higher and lower temperatures on the melting and crystallization curves, respectively. This is because, even if in theory the powder could remain operable at temperatures further along the melting curve, in practice, some of the applied powder may begin to agglomerate even at these early stages along the melting curve. Therefore, to ensure optimal printability, it would be useful to know the exact range in which such agglomeration or powder decomposition risk can be avoided to the greatest extent possible. Other methods provide an apparent wider operating range (e.g. T according to ISO 11357-1). ei,m and T ef,c and ), gives no true indication of the extent to which the risk of warping or curvature of the part is minimized. Various points related to the above are illustrated in Figure 1.

[0086] Thus, in one embodiment, the granular composition of the second aspect has a sinterability region of at least 0° C. Having such a value ensures that there is no overlap between the point at which the granular composition begins to melt and the point at which it begins to crystallize. In preferred embodiments, the granular composition has a sinterability region of at least 15° C., or at least 20, or at least 25, or at least 30, or at least 35° C., or 15-60, or 15-45, or 18-60, or 18-45° C.

[0087] However, due to the inherent properties of certain additives and the amounts used, the sinterable region of a non-uniform granular composition may vary (or may differ locally), so it may be more appropriate to measure the density only for the PHA powder component alone. Thus, in one embodiment, the PHA powder of the second aspect has a sinterable region of at least 0°C. Having such a value ensures that there is no overlap between the point at which the PHA powder begins to melt and the point at which it begins to crystallize. In a preferred embodiment, the PHA powder has a sinterable region of at least 15°C, or at least 20, or at least 25, or at least 30, or at least 35°C, or 15-60, or 15-45, or 18-60, or 18-45°C.

[0088] In yet other embodiments, the sinterable region of the granular composition and / or PHA powder is between 15 and 50 degrees Celsius, or between 15 and 42°C, or between 18 and 42°C, or between 20 and 40°C, as determined by ISO 11357-1 (2009).

[0089] The inventors have surprisingly found that the thermal properties of the PHA powder, especially the sinterable region, can be dramatically improved through a specific heat treatment method. The PHA powder and / or granular composition of the second aspect of the invention is preferably subjected to a heating step (b) as described elsewhere herein below with respect to the first aspect of the invention. The inventors have demonstrated herein that a specific processing of the raw powder can improve its thermal properties so as to render it suitable for use in additive manufacturing processes.

[0090] As mentioned above, physical properties can vary significantly between different PHA polymers. It is therefore understood that there is no single preferred Tm,onset or Tc,onset value, but rather that the sinterability region is generally more important. Nevertheless, the PHA powder and / or granular composition should be selected such that its aforementioned onset value is compatible within the operating limits of the additive manufacturing device with which it is used. Thus, in one embodiment, the PHA has a Tm,onset value of at least 100°C, or at least 120°C, or at least 125°C, or between 100 and 180°C, or between 120 and 150°C. Furthermore, in one embodiment, the PHA powder has a Tc,onset value of less than 135°C, or less than 125°C, or less than 110°C, or between 90 and 130°C, or between 95 and 125°C.

[0091] In yet further embodiments, the PHA powder is configured to have a specified crystalline property. Crystallinity refers to the degree of structural order in a solid. For polymers, particularly semi-crystalline polymers, crystallinity is a measure of the percentage of the volume of a particular substance that is in a crystalline state, as opposed to being amorphous. Crystallinity is known to affect many mechanical properties of a material, such as its hardness, density, and thermal properties. The crystallinity of a substance can be measured by a number of means, such as X-ray crystallography or calorimetry. In one embodiment, the PHA has a crystallinity of at least 10%, or at least 20%, or at least 30%, or at least 50%, or at least 60%, or at least 65%. In a preferred embodiment, the crystallinity is determined by dividing the enthalpy change (ΔH) determined by DSC by the theoretical maximum of 146 Joules per gram (J / g).

[0092] In order to maximize suitability for use in various additive manufacturing processes, it is desirable that the granular composition and / or PHA powder of the second aspect be configured to have a consistent particle size and particle size distribution. It is known to those skilled in the art that a particular particle size distribution may promote optimal processability and flowability in additive manufacturing processes. Thus, in one embodiment according to the second aspect of the invention, the granular composition and / or PHA powder has a D50 particle size in the range of 30-100 microns, or 20-50 microns, or 40-50 microns. Excessively small particles, such as particles less than about 20 microns, may inhibit the flowability of the powder particles. Conversely, if the particles tend to be too large, for example more than 50 microns, depending on the application requirements, the resolution of the final printed object will be affected. Furthermore, particles that are too large also tend not to be well packed, so that voids may be present in the fused object.

[0093] For particle size distribution, the median is called D50 (or x50 if certain ISO guidelines are followed). D50 is the diameter (specified in microns herein unless otherwise stated) at which the distribution is divided into two halves, one above this diameter and the other below this diameter. As used in the embodiment of the third aspect of the present specification, particle size distribution and D50 particle size are determined by laser diffraction particle size analysis according to ISO 13320-1. Other related terms correspond to the median of other methods of analyzing the distribution of particles. For example, Dv50 (or Dv0.5) is the median of the volume distribution. Similarly, Dn50 is used for number distribution and Ds50 is used for areal distribution. Since the primary result of laser diffraction is the volume distribution, the default D50 mentioned is the volume median, and D50 typically means Dv50 without the "v". Similarly, other values ​​such as D10 and D90 also used herein follow a similar nomenclature and relate to the 10th and 90th percentiles of particle size by volume distribution, respectively.

[0094] In one embodiment, the granular composition and / or PHA powder therefore has a D10 value of at least 15 microns, or at least 20 microns, or at least 30 microns, and / or a D90 value of less than 100 microns, or less than 90 microns, or less than 80 microns.

[0095] The particle size and / or particle size distribution can be adjusted as required through various methods, including those described elsewhere herein with respect to the first embodiment of the present invention. In particular, the screening step (e) described in relation to the first embodiment can be particularly useful for narrowing the particle size distribution, while the grinding method disclosed in step (c) above can be particularly useful for reducing the average particle size. Of course, it is contemplated that a combination of screening and grinding, among other methods, can be used to process the granular composition and / or PHA powder according to specific design requirements.

[0096] A third aspect of the invention is an additive manufacturing process comprising a granular composition and / or a PHA powder according to any of the embodiments of the second aspect of the invention and / or any granular composition suitable as powder building material for an additive manufacturing process according to any of the embodiments of the first aspect.

[0097] According to a preferred embodiment of the third aspect, the process comprises the steps of: (a) providing a layer of a granular composition for additive manufacturing comprising a PHA powder according to any of the embodiments of the second aspect; (b) optionally selectively depositing a liquid composition onto the layer of granular composition, where at least one of the granular composition or the liquid composition comprises a fusing agent; (c) applying electromagnetic radiation to either (i) specific locations on the layer of granular composition or (ii) locations of the liquid composition selectively deposited on the granular composition, where the granular composition undergoes melting to form a fused portion at least in a portion of the locations where the electromagnetic radiation and / or the liquid composition is applied, according to computer data corresponding to a portion of the three-dimensional object to be formed; and (d) repeating steps (a), optionally steps (b), and (c) multiple times to form a fused three-dimensional object.

[0098] The granular composition and / or PHA powder defined in the present invention are particularly suitable for various rapid prototyping / rapid manufacturing methods, including but not limited to selective laser sintering (SLS), powder / binder methods, and multi-jet fusion (MJF). In the SLS process, polymer particles are introduced into a chamber and selectively exposed to a laser beam for a short period of time, which melts the particles affected by the laser beam. The molten particles coalesce and rapidly become solid again, obtaining a solid mass. This process can simply and quickly produce three-dimensional structures by constantly applying new layers and repeatedly exposing the layers to laser light to melt them and then coalesce in the form of a three-dimensional object.

[0099] Other additive manufacturing methods that can suitably incorporate the granular composition and / or PHA powder of the present invention include high speed sintering (HSS) and multi-jet fusion (MJF). These methods utilize multiple jets that deposit successive layers of infrared absorbing fluid onto powder material, and then apply energy, typically infrared energy exposure, to selectively melt the powder layers. Yet another suitable additive manufacturing process is 3D printing by electrophotography. This method uses a rotating photoconductor that builds up the layers of an object layer by layer from a base.

[0100] Regardless of the variations in this particular process, each of these 3D printing methods typically utilizes a similar arrangement of movable powder beds used to manufacture the object. Moreover, each process, despite the slightly different heating mechanisms used, applies similar stresses to the object constructed in each case, thus necessitating the utilization of powders with similar material performance. Thus, in one embodiment, the granular composition and / or PHA powder of any of the described aspects of the present invention is used in an SLS process, or an MJF process, or an HSS process, or a powder / binder process, or an electrophotographic 3D printing process.

[0101] In one embodiment the invention involves a method of forming a three-dimensional object comprising the steps of forming a layer of a granular composition according to any of the embodiments of the second aspect of the invention and / or a layer of a granular composition made according to any of the embodiments of the first aspect of the invention, selectively depositing a liquid composition onto the layer of granular composition in accordance with computer data corresponding to a shape of at least a portion of the three-dimensional object, where at least one of the granular composition or the liquid composition comprises a fusing agent, applying electromagnetic radiation to at least one location of the layer of granular composition onto which the liquid composition has been deposited, whereby the granular composition undergoes melting at said at least one location, and repeating the aforementioned steps a number of times to form the three-dimensional object.

[0102] The method according to the third aspect utilises a granular composition as described or made by any of the embodiments of either the first or second aspect of the invention. Advantageously, the granular composition of the second aspect is made according to the method according to the first aspect.

[0103] The formation of three-dimensional objects from granular compositions can be promoted or aided by the inclusion of additional materials. Such materials can be granular solids or liquids and can be interspersed within the polymer powder or deposited thereon, for example by selective jetting. Fusing agents, among others described in WO2017196361A1, are commonly included examples of additional materials commonly used in MJF or HSS processes. Fusing agents typically include, as active components, one or more energy absorbers, or components, capable of absorbing electromagnetic radiation to generate heat. They may also include thermal initiators and / or photoinitiators. Such components may absorb electromagnetic radiation in the UV, UV-vis, visible, near infrared, or infrared parts of the spectrum. These fusing agents, when applied in selective locations, can melt only in the areas where they are applied and / or where electromagnetic radiation is applied to the polymer powder.

[0104] Non-limiting examples of fusing agents include pigments such as carbon black, tungsten bronze, molybdenum bronze, and metal nanoparticles, phosphates with various counterions such as copper, zinc, iron, magnesium, calcium, and strontium, and silicates, especially silicates with the same or similar counterions as phosphates.In addition, laser dyes and cyclic lactone dye precursors may be used.Near infrared absorbing dyes may also be used, including examples such as aluminum dyes, tetraaryldiamine dyes, cyanine dyes, pthalocyanine dyes, dithiolene dyes, and combinations thereof.

[0105] Additionally, conjugated polymers can be used as fusing agents. Examples of near infrared absorbing conjugated polymers include poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), polythiophene, poly(p-phenylene sulfide), polyaniline, poly(pyrrole), poly(acetylene), poly(p-phenylenevinylene), polyparaphenylene, or combinations thereof.

[0106] The amount of fusing agent can vary depending on the components used. In one embodiment, the fusing agent can be between 0.1% and 20% by weight. In one example, the concentration of the energy absorber in the fusing agent can be between 0.1% and 15% by weight. In another example, the concentration can be between 0.1% and 8% by weight. In yet another example, the concentration can be between 0.5% and 2% by weight. In a particular example, the concentration can be between 0.5% and 1.2% by weight.

[0107] The coalescent may also include one or more initiators capable of initiating polymerization of the resin components. These initiators include thermal initiators and photoinitiators.

[0108] Thermal initiators include, but are not limited to, thermal free radical polymerization initiators and peroxides. Examples of thermal free radical polymerization initiators include, but are not limited to, azo compounds such as azoisobutyronitrile (AIBN), 1,1'-azobis(cyclohexanenitrile), 1,1'-azobis(2,4,4-trimethylpentane), CC labile compounds such as benzopinacol, peroxides, and mixtures thereof.

[0109] Examples of peroxides potentially suitable as thermal initiators include, for example, percarbonates (of formula OC(O)O), peroxyesters (of formula C(O)OO), diacyl peroxides (also known as peranhydrides) (of formula C(O)OOC(O)), dialkyl peroxides or perethers (of formula -OO), hydroperoxides (of formula -OOH), etc. The peroxides may also be oligomeric or polymeric in nature. Examples of organic peroxides include tertiary alkyl hydroperoxides (e.g., t-butyl hydroperoxide, etc.), other hydroperoxides (e.g., cumene hydroperoxide, etc.), ketone peroxides (perketones, which are addition products of hydrogen peroxide and ketones, such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, and acetylacetone peroxide, etc.), peroxyesters or peracids (e.g., t-butyl perester, benzoyl peroxide, peracetate, and perbenzoate, lauroyl peroxide, including (di)peroxyesters, perethers (e.g., peroxydiethyl ether, etc.), and the like.

[0110] Thermal free radical polymerization initiators may include, for example, percarbonates, peresters, or peranhydrides. Peranhydrides are, for example, benzoyl peroxide (BPO) and lauroyl peroxide (commercially available under the Laurox trademark). Peresters are, for example, t-butyl perbenzoate and 2-ethylhexyl perlaurate. Percarbonates are, for example, di-t-butyl percarbonate and di-2-ethylhexyl percarbonate or monopercarbonate.

[0111] Finally, photoinitiators for three-dimensional printing are also known and are described, inter alia, in US Pat. No. 9,951,198.

[0112] The granular composition and fusing agent described herein may be present in one single composition / formulation, or they may be stored separately and selectively applied to each other during an additive manufacturing process. Accordingly, an embodiment of the present invention is directed to a kit of materials comprising at least one combination of: (a) a granular composition or PHA powder formed by or according to any of the embodiments of the first or second aspects described elsewhere herein; (b) a fusing agent, the fusing agent further comprising an energy absorber, a thermal initiator, or a photoinitiator.

[0113] A fourth aspect of the invention is an article printed via any of the processes described in the third aspect. The article printed according to the fourth aspect is preferably derived from a granular composition according to any of the embodiments of the second aspect, which preferably originates via any of the embodiments described according to the first aspect of the invention. Such articles may be utilized in a variety of applications and / or markets, including prototypes, automotive, aerospace, medical, dental, lighting, electrical, and footwear, to name a few non-limiting examples.

[0114] These following examples further illustrate the invention but, of course, should not be construed as in any way limiting its scope. EXAMPLES

[0115] The following examples are intended as illustrations of certain preferred embodiments of the invention, and no limitation of the invention is implied. Table 1 shows the D10 / D50 / D90 particle size (expressed in microns or μm), loose bulk density (FBD) and packed bulk density (TBD) (expressed in g / ml), melting temperature (T m ), peak crystallization temperature (T c ), melting point onset temperature (T m ,onset), crystallization onset temperature (T c A summary of the performance of each Example / Comparative Example is provided, including a listing of the melting point (T), melting temperature ...

[0116] The means by which each granular composition used in the examples herein is provided is further described below. Specifically, unless otherwise specified below (e.g., C8 was a milled version of C7), Comparative Examples 1-10 (C1-C10) were as provided by their suppliers and were not further processed by the inventors. Further explanatory details of each of these materials are provided below. Additionally, the specific means by which the granular compositions used in Examples 1-8 are used are described in more detail below.

[0117] Comparative Examples 1 to 10 C1 is a dispersible powder of poly(3-hydroxybutyrate) (PHB) manufactured by TianAn Biologic Materials and supplied by Helian Polymers (The Netherlands), commercially available under the name Enmat Y3000, analyzed as shown in Table 1 below, and designated "dispersible Enmat Y3000".

[0118] C2 is a PHB dispersible powder available from Biomer Biopolyesters, Germany, analyzed as shown in Table 1 below and designated "Biomer dispersible".

[0119] C3 is a dispersible powder of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) manufactured by TianAn Biologic Materials and supplied by NaturePlast (France), commercially available under the name Enmat Y1000, analyzed as shown in Table 1 below, and designated "dispersible Enmat Y1000".

[0120] C4 is a PHBV dispersible powder marketed under the trade name Ceraflour and supplied by Byk (The Netherlands), analysed as shown in Table 1 below and designated "dispersible Ceraflour".

[0121] C5 is a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) PHBH powder having a melting point of 144° C. and further properties identified below in Table 1. It is identified in Table 1 as “PHBH Powder 1.”

[0122] C6 is a PHBH powder having a melting point of 100° C. and further properties specified in Table 1 below, where it is designated “PHBH Powder 2.”

[0123] C7 is a PHBH material having a melting point of 152° C. and further properties specified below in Table 1, where it is designated "PHBH Granules."

[0124] C8 is the PHBH granule material of C7 cryogenically milled on a Hosokawa UPZ 100 cryomill at -40°C with a pin disc speed of 20000 rpm. The resulting powder was sieved through a 125um sieve to remove pass-through particles. The final powder was analyzed as shown in Table 1 below and designated "C7 after Cryomill".

[0125] C9 is a PHBH material provided in granular form having a melting point of 146° C. and further properties specified in Table 1 below, where it is designated “PHBH Granules 2.”

[0126] C10 is a PHBH material provided in granular form having a melting point of 131° C. and further properties specified in Table 1 below, where it is designated "PHBH Granules 3."

[0127] Examples 1 to 8 Example 1 190kN force (378kN / cm in this example) 2 Tablets of PHB Y3000 with a diameter of 0.4 cm were pressed from the friable powder (powder of C1) using a press mould at a pressure equal to 1000 MPa (equivalent to a pressure of 1000 MPa). The tablets were then ground to a powder on a Retsch ZM1 device equipped with a 1 mm sieve. The fraction of particles less than 200 microns was isolated by sieving. The final granular composition of the PHB powder was analysed as shown in Table 1 and is designated "compacted C1". Example 1a

[0128] As disclosed in Example 1 above, 3 grams of the final powder were placed in a 25 ml round bottom flask and heated to 100° C. with electrical heating while rotating. The flask was placed under vacuum (1 mbar) and then backfilled with N2 to remove all air. This procedure was repeated three times. The temperature was increased to 145° C. and maintained at that temperature for 1 hour. The temperature was then increased to 155° C. over 1 hour and then to 165° C. over 1.5 hours. After the minimum steps, the powder was cooled. The final granular composition of the PHB powder was analyzed as shown in Table 1 and is designated "After compaction / annealing C1".

[0129] Example 2 10 kg of Ceraflour dispersible powder from PHBV (powder from C4) was compacted in a Bepex Labor Kompaktor L200 / 50 (roller width 5 cm) with a force of 40 kN. Since the compactor works with two rollers pressed against each other, the specific linear pressure of the press can be calculated. This is the force divided by the roller width, 40 / 5=8 kN / cm. With the rollers, the powder was pressed into pill shapes with a cross section of 4.6 x 1 cm, and then the pills were crushed into flakes on a Retsch SM2000 machine equipped with an 8 mm sieve. The flakes were then mixed with fresh dispersible powder from C4 in a weight ratio of 2:1 (flakes:C4 powder). This mixture was compacted again with a force of 110-120 kN (specific linear pressure 24 kN / cm). The resulting pills were milled first in an SM2000 equipped with an 8 mm sieve and then again for a second time with the 8 mm sieve replaced by a 4 mm sieve. The final flakes were then milled into powder using a Hosokawa ACM (Air Classifier Mill) and a sieve to remove fines. The final granular composition of PHBV powder was analyzed as shown in Table 1 and is designated "Post-Consolidation C4".

[0130] Example 3 As disclosed in Example 2 above, 2 kg of the final powder was placed in a 10 liter round bottom flask and heated to 100°C while rotating in a heated oil bath. The flask was placed under vacuum (1 mbar) and then backfilled with N2 to remove all air. The temperature of the oil bath was heated to 145°C and maintained at that temperature for 1 hour while purging with a N2 flow of 7.2 liters / hour at atmospheric pressure. The temperature was then increased stepwise to 150°C, 155°C, 160°C, 165°C, and finally 168°C, whereby the temperature of each respective step was maintained for 1 hour before the temperature was further increased. After that smallest step, the powder was cooled under the same N2 flow by removing the flask from the oil bath.

[0131] The final granular composition of PHBV powder was analyzed as shown in Table 1 and is designated "Consolidated / Annealed C4".

[0132] Example 4 First, 5 kg of PHBH powder (from C5) was sieved through a 125um sieve to remove larger particles. Then, 2.7 kg of this sieved powder was placed in a 10 liter round bottom flask and heated to 100°C while rotating in a hot oil bath. The flask was then purged with a flow of 8 liters per hour with N2 under a vacuum of 4 mbar. After a drying step of 1.5 hours, the temperature of the oil bath was heated to 115°C and maintained at that temperature for 1 hour. The temperature was then increased stepwise to 120°C, 125°C, 130°C, and finally to 135°C, whereby the temperature of each respective step was maintained for 1 hour before the temperature was further increased. After that minimum step, the powder was cooled under N2 and vacuum by removing the flask from the oil bath. The final granular composition of PHBH powder was analyzed as shown in Table 1 and is designated as "C5 after annealing".

[0133] Example 5 First, 10 kg of PHBH powder (of C5) was compacted into 10x30 mm pills with a diameter of 5 mm at a pressure of 80 kN using a Bepex Labor Kompaktor L200 / 50. The pills were then crushed into flakes in a Retsch SM2000 device equipped with an 8 mm sieve. Afterwards, 3.8 kg of the resulting flakes were placed in a 10 liter round-bottom flask and heated to 100°C while rotating in a hot oil bath. The flask was placed under vacuum pressure of 1 mbar while purging with a flow of 7.2 liters per hour of N2. After a drying stage of 1.5 hours, the temperature of the oil bath was heated to 115°C and maintained at that temperature for 1 hour. The temperature was then increased stepwise to 120°C, 125°C, 130°C, and finally to 135°C, whereby the temperature in each respective step was maintained for 1 hour before the temperature was further increased. After that small step, the flask was removed from the oil bath and the powder was cooled under N2 and reduced pressure.

[0134] The final flakes were ground into powder in a cryogenic mill equipped with a 100 μm sieve. The final granular composition of the PHBH powder was analyzed as shown in Table 1 and is designated as "Consolidated / Annealed C5".

[0135] Example 6 In this example, 3.5 kg of PHBH granular material of C7 was placed in a 10 liter round bottom flask and heated to 105°C while rotating in a heated oil bath. The flask was purged with a flow of 10 liters per hour with N2 under a vacuum of 1 mbar. After a drying step of 1 hour, the temperature of the oil bath was heated to 110°C and maintained at that temperature for another hour. The temperature was then increased stepwise to 115°C, 120°C, 125°C, and 130°C, thereby increasing the temperature further after maintaining the temperature for 1 hour at each of the previous steps. The temperature was then increased one more time to 135°C, after which this final temperature was maintained for 2 hours. After that minimum step, the flask was removed from the oil bath and the powder was cooled under N2 and vacuum. The resulting annealed granules were ground to powder in an ACM (Air Classifier Mill). The final granular composition of PHBH powder was analyzed as shown in Table 1 and is designated "Annealed C7".

[0136] Example 7 3.7 kg of PHBH granular material C9 was placed in a 10 liter round bottom flask and heated to 105°C while rotating in a heated oil bath. The flask was purged with a flow of 7.2 liters per hour with N2 under a vacuum of 1 mbar. After a drying step of 1.5 hours, the temperature of the oil bath was heated to 100°C and maintained at that temperature for 1 hour. The temperature was then increased stepwise to 110°C, 115°C, 120°C, 125°C, 130°C, and finally to 135°C, whereby the temperature of each respective step was maintained for 1 hour before the temperature was further increased. After the smallest step, the flask was removed from the oil bath and the powder was cooled under N2 and vacuum. The resulting annealed material was then ground to powder in an ACM (Air Classifier Mill). The final granular composition of PHBH powder was analyzed as shown in Table 1 and is designated "Annealed C9".

[0137] Example 8 110 g of PHBH granular material of C10 was placed in a 250 ml round bottom flask and heated to 85° C. while rotating in a heated oil bath. The flask was purged with a flow of 7.2 liters per hour of N2 while applying a vacuum of 1 mbar. The temperature of the oil bath was then heated stepwise to 130° C. with intermediate steps of 5° C., whereby the temperature was maintained for 20 minutes after each successive step temperature was achieved. After this designated step, the temperature reached a temperature of 130° C. and was held at that final temperature for an additional 100 minutes. After that minimum step, the flask was removed from the oil bath and the powder was cooled under N2 and vacuum. The resulting annealed material was then powdered by cryogenic grinding. The final granular composition of the PHBH powder was analyzed as shown in Table 1 and is designated as “Annealed C10”.

[0138] D10 / D50 / D90 particle size The particle size values ​​D10, D50, and D90 were measured according to ISO 13320-1, as referred to elsewhere herein. The particle size distribution (PSD) of the powder from which these values ​​were derived was measured using laser diffraction on a SYMPATEC HELOS system (model HELOS / H3982) equipped with a RODOS dry dispersion unit, R5 4.5-875um. D50 represents the statistical volume median of the particle size, while D10 / D90 represent the 10th and 90th percentiles of these values, respectively. This value for the various samples was recorded and reported in Table 1 below. Values ​​are reported in microns unless otherwise stated.

[0139] density The loose bulk density (FBD) or apparent density was measured according to ASTM D1895-96. Test method A described herein was used. A cylindrical measuring cup with a volume of 100 ml and a diameter of 40 mm was connected to a funnel with a 9.5 mm diameter opening at the bottom, such that the funnel was mounted at a height of 38 mm above the measuring cup. The packed bulk density (TBD) was determined by placing the cup on a vibrating plate with an amplitude of 0.2 mm until the volume was constant. The values ​​for each composition are reported in grams per milliliter (g / ml) in Table 1 below.

[0140] T m , T c , T m ,onset,T c , onset, and sintering region T m , T m , T c , T m ,onset,T c The temperature, onset, and sinterability regions were determined via Differential Scanning Calorimetry (DSC). DSC measurements were performed on a Mettler DSC823e equipped with an FS0812R0 sample robot and a Mettler TS0800GC1 gas control. All samples were recorded in aluminium sealed pans. Calibration of the DSC instrument was performed with indium. DSC thermograms of the materials (quantities of 3–10 mg) were then recorded at a scan rate of 10 °C / min in the temperature range T f,m The temperatures ranged from a higher 25 °C to 15 °C (± 5 °C). After reaching the maximum temperature, the temperature was held constant for 1 min and then cooled to 25 °C at a scan rate of 10 °C / min. Data collection was performed using STARe software.

[0141] Next, T m , T c , T m ,onset,T c The values ​​of , onset, and sinterability region were determined by DSC thermography according to ISO 11357-3 (2009). i,mwas determined by taking the first detectable deviation of the curve from the extrapolated starting baseline of the melting peak curve when the sample being evaluated was heated at a constant heating rate of 10°C / min as evidenced by the DSC method during the first heating cycle. Furthermore, the "first detectable deviation of the curve from the extrapolated starting baseline" was defined as the point at which the thermograph showed a deviation of at least 0.15 mW from the baseline. The T derived from this ISO method i,m Record the value of T and enter it in Table 1. m , and is reported as onset.

[0142] On the other hand, T f,c was then determined according to the same ISO method, which means the last detectable deviation of the curve from the extrapolated end baseline of the crystallization peak curve of the material being evaluated, but the "last detectable deviation" was defined as the point where the deviation from the baseline was less than 0.1 mW. f,c Record the value of T and enter it in Table 1. c , and is reported as onset.

[0143] In a similar fashion, T m and T c , respectively. p,m and T p,c These values ​​are also reported in Table 1 below.

[0144] Finally, the sinterable region was determined for each sample by T m ,onset to T c , by subtracting the value of onset, i.e., T in ISO 11357-3 i,m -T f,c This value is reported in Table 1 below in the column marked "ΔT."

[0145] The T reported herein m , T m ,onset,T c , T cAll values ​​for temperature, onset, and sinterability region are expressed in degrees Celsius (° C.) unless otherwise stated. GPC The number average molecular weight (Mn) and weight average molecular weight (Mw) were determined by gel permeation chromatography (GPC) at 35°C against polymethylmethacrylate in a solution of hexafluoroisopropanol (HFIP) and 0.1 wt% potassium trifluoroacetate. The separation column used was provided by Polymer Standards Service GmbH (Germany). Three model PFG linear XL 7 μm, 300×8.0 mm columns (particle size: 7 um) with precolumn were then applied. GPC analysis was performed using a Viscotek GPC Max (system ID: LT-8) equipped with a Viscotek Triple detector array 305, including ultraviolet (UV), refractive index (RI), differential viscometer (DV), and right angle light scattering (RALS) detectors. Finally, data acquisition and calculations were performed using Malvern OmniSEC 4.7.0 software. [Table 1]

[0146] [Table 2]

[0147] nd = not determined, but MW data is similar to Example 5 (consolidation is not expected to change MW data)

[0148] Unless otherwise specified, the term weight percent refers to the mass of a particular component relative to the total composition in which it is incorporated.

[0149] The use of the terms "a" and "an" and "the" and similar references in the context of describing the present invention (particularly in the context of the claims that follow) should be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Unless otherwise indicated, the terms "comprising," "having," "including," and "containing" should be construed as open-ended terms (i.e., meaning "including, but not limited to"). The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referring to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually set forth herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "etc.") provided herein is intended merely to better clarify the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0150] Preferred embodiments of the present invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of these preferred embodiments may become apparent to those skilled in the art upon reading the foregoing description. The inventors anticipate that those skilled in the art will employ such variations as necessary, and the inventors intend the invention to be practiced otherwise than as specifically described herein. Accordingly, the present invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto to the extent permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the present invention unless otherwise indicated herein or clearly contradicted by context.

[0151] While the present invention has been described in terms of specific embodiments, including presently preferred modes of carrying out the invention, those skilled in the art will recognize that there are numerous variations and permutations of the above-described systems and techniques which fall within the spirit and scope of the invention, as set forth in the appended claims.

Claims

1. A granular composition for additive manufacturing, comprising polyhydroxyalkanoate (PHA) powder, consisting of polyhydroxyalkanoate (PHA) powder, or consisting essentially of polyhydroxyalkanoate (PHA) powder, wherein the granular composition and / or the PHA powder has a. a bulk density exceeding 0.30 g / mL as determined by ASTM D1895-96, and b. A sinterable region exceeding 15 degrees Celsius, the sinterable region having a value determined by subtracting T ｉ，ｍ from T ｆ，ｃ according to ISO 11357-1 (2009), and being a granular composition having a sinterable region. ｉ，ｍ from T ｆ，ｃ to be subtracted, and being a granular composition having a sinterable region.

2. The PHA powder has a crystallinity exceeding 30%, or exceeding 40%, or exceeding 50%, or exceeding 60%, and the crystallinity is determined by dividing the melting enthalpy (ΔH) determined by the DSC method by the theoretical maximum value of 146 joules per gram (J / g). The granular composition according to Claim 1.

3. When the sintering region of the granular composition and / or the PHA powder is determined by ISO 11357-1 (2009), it is 15 to 50 °C, or 15 to 42 °C, or 18 to 42 °C, or 20 to 40 °C. The granular composition according to Claim 1.

4. The PHA powder has a bulk density of 0.3 to 0.65 g / mL, or 0.4 to 0.5 g / mL. The granular composition according to Claim 1.

5. The granular composition comprises polyester, consists essentially of polyester, or consists of polyester. The granular composition according to Claim 1.

6. The granular composition and the PHA powder comprise polyhydroxyalkanoate (PHA), consist essentially of polyhydroxyalkanoate (PHA), or consist of polyhydroxyalkanoate (PHA). The granular composition according to Claim 1.

7. The granular composition and / or the PHA powder contains poly-3-hydroxybutyrate (P3HB), poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO), polyhydroxydecanoate (PHD), polyhydroxydodecanoate (PHDD), or a copolymer thereof, and is essentially composed of poly-3-hydroxybutyrate (P3HB), poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO), polyhydroxydecanoate (PHD), polyhydroxydodecanoate (PHDD), or a copolymer thereof, or is composed of poly-3-hydroxybutyrate (P3HB), poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO), polyhydroxydecanoate (PHD), polyhydroxydodecanoate (PHDD), or a copolymer thereof, the granular composition according to claim 1.

8. The granular composition and / or the PHA powder contains P3HB, is essentially composed of P3HB, or is composed of P3HB, the granular composition according to claim 1.

9. The granular composition and / or the PHA powder has a D50 particle size of 30 to 100 microns as determined by laser diffraction particle size analysis in accordance with ISO 13320-1, the granular composition according to claim 1.

10. The granular composition and / or the PHA powder has a D90 particle size of 100 microns or less and a D10 particle size of at least 30 microns as determined by laser diffraction particle size analysis in accordance with ISO 13320-1, the granular composition according to claim 1.

11. The PHA powder has a Tm, onset value of at least 100 °C, or at least 120 °C, or at least 125 °C, the granular composition according to claim 1.

12. The PHA powder has a Tc, onset value of less than 135 °C, or less than 125 °C, or less than 110 °C, the granular composition according to claim 1.

13. The granular composition according to claim 1, further comprising one or more additives.

14. The granular composition according to claim 13, wherein the additive includes a flow aid, and the additive is present in an amount of 0.5% to 20% by weight based on the entire granular composition.

15. The PHA of the PHA powder has a weight average molecular weight Mw of 200,000 to 1,000,000 g / mol, which is determined by gel permeation chromatography based on polymethyl methacrylate using hexafluoroisopropanol (HFIP) as an eluent, and the granular composition according to claim 1.

16. A method of forming an object through a laminated manufacturing process, comprising: (a) providing a layer of a granular composition for laminated manufacturing containing the PHA powder according to any one of claims 1 to 15; (b) optionally, selectively depositing a liquid composition on the layer of the granular composition, wherein at least one of the granular composition or the liquid composition contains a fusing agent, the step of selectively depositing; (c) applying electromagnetic radiation to (i) a specific location on the layer of the granular composition, or (ii) the location of the liquid composition selectively deposited on the granular composition, the step of applying, wherein the granular composition is melted at least in part at the location where the electromagnetic radiation and / or the liquid composition is applied according to computer data corresponding to a part of the three-dimensional object to be formed, to form a fused part; (d) repeating step (a), optionally step (b), and step (c) a plurality of times to form a fused three-dimensional object.

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