Compositions suitable for 3D printing

Abstract

The present invention provides a composition suitable for 3D printing, comprising: The present invention relates to a polyester derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, the polyester having a degree of polymerization of 0.6 or less, the degree of polymerization being the ratio of the number of reacted functional groups to the maximum number of functional groups capable of reacting, the polyester comprising a solid filler and a diluent. The present invention also relates to a method for preparing a molded object, the method comprising the steps of providing a composition described herein, extruding the composition through a printer nozzle to form layers of the composition in a desired shape, stacking the layers on top of each other to form the molded object, and subjecting the molded object to a curing step to form a cured molded object, the curing step occurring during and / or after the extrusion step. The above molded object is also claimed.

Description

[Technical Field]

[0001] The present invention is directed to a composition suitable for 3D-printing. The present invention is also directed to the use of the composition in 3D printing and to the molded objects thus obtained. [Background technology]

[0002] 3D printing is an attractive method for obtaining custom-made objects and is finding widespread applications in many fields of use.

[0003] The problem with the current state of the art of 3D printed objects is that while it allows for the printing of thermoplastic polymers, thermosetting polymers have proven very difficult to process.

[0004] There is a need in the art for compositions based on thermosetting polymers that can be processed through 3D printing to form shaped objects and thus exhibit good thermal stability. Such compositions would be particularly attractive if they were based on biobased, fossil-free components. The compositions should be capable of providing 3D shapes with good stability and an attractive visual appearance. The compositions would also be particularly attractive if they were reusable and / or biodegradable. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides such a composition. [Means for solving the problem]

[0006] The present invention provides a composition suitable for 3D printing, comprising: A polyester derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, wherein the polyester has a degree of polymerization of 0.6 or less, the degree of polymerization being the ratio of the number of functional groups reacted to the maximum number of functional groups that can react. solid filler, Diluent The composition comprises:

[0007] The compositions according to the present invention can be processed using a 3D printer to form molded objects, which can be subjected to a curing step during or after printing. The polyesters used in the present invention are thermosetting materials, which provide good thermal stability of the molded objects. By appropriate selection of the filler and the source of the polyester, bio-based, fossil-free, renewable, recyclable, and / or biodegradable compositions can be obtained. Further advantages of the compositions of the present invention and specific and further embodiments thereof will become apparent from the further specification.

[0008] The present invention also provides a method for preparing a shaped object, comprising the steps of: Providing a composition described herein; extruding the composition through a printer nozzle to form layers of the composition in a desired shape and building up the layers on top of each other to form a shaped object; subjecting the shaped body to a curing step to form a hardened shaped body, wherein the curing step occurs during and / or after the extrusion step; The method includes the steps of:

[0009] The present invention further provides a 3D printed object comprising a polyester derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, wherein the polyester has a degree of polymerization of at least 0.5, particularly at least 0.6, where the degree of polymerization is the ratio of the number of reacted functional groups to the maximum number of functional groups that can react, and a filler.

[0010] The invention will be explained in more detail below. DETAILED DESCRIPTION OF THE INVENTION

[0011] polyester The starting composition according to the present invention comprises a polyester derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, wherein the polymer has a degree of polymerization of 0.1 to 0.6, the degree of polymerization being the ratio of the number of functional groups reacted to the maximum number of functional groups that can react.

[0012] The aliphatic polyalcohol used in the present invention contains at least two hydroxy groups, particularly at least three hydroxy groups. Generally, the number of hydroxy groups is 10 or less, more particularly 8 or less, or even 6 or less, particularly 2 or 3. The polyalcohol has 2 to 15 carbon atoms. More particularly, the polyalcohol has 3 to 10 carbon atoms. Preferably, the polyalcohol does not contain heteroatoms. More particularly, the polyalcohol is an aliphatic polyalkanol containing only C, H, and O atoms. Preferably, the polyalcohol does not contain non-carbon groups other than hydroxy groups. In a preferred embodiment of the present invention, the polyalcohol contains a relatively large number of hydroxy groups compared to its number of carbon atoms. For example, the ratio of the number of hydroxy groups to the number of carbon atoms is 1:4 (i.e., one hydroxy group per four carbon atoms, or eight carbon atoms per dialcohol) to 1:1 (i.e., one hydroxy group per carbon atom). In particular, the ratio of the number of hydroxy groups to the number of carbon atoms is from 1:3 to 1:1, more in particular from 1:2 to 1:1. Particularly preferred polyalcohol groups are those in which the ratio is from 1:1.5 to 1:1.

[0013] Compounds with a 1:1 ratio of hydroxy groups to carbon atoms are believed to be particularly preferred.

[0014] Examples of suitable polyalcohols include tri-alcohols selected from glycerol, sorbitol, xylitol and mannitol, and dialcohols selected from 1,2-propanediol, 1,3-propanediol and 1,2-ethanediol. The use of compounds selected from the group of glycerol, sorbitol, xylitol and mannitol is preferred, and the use of glycerol is particularly preferred.

[0015] The preference for glycerol is based on the following: First, glycerol has a melting point of 20°C, which allows for easy processing, especially compared to xylitol, sorbitol, and mannitol, which all have melting points well above 90°C. Furthermore, glycerol has been found to result in high quality polymers, thus combining the use of readily available sources of material with good processing conditions and a high quality product. Mixtures of various types of alcohols can also be used.

[0016] However, it is preferred that the polyalcohol consists of at least 50 mol%, preferably at least 70 mol%, more particularly at least 90 mol%, or even at least 95 mol% of glycerol, xylitol, sorbitol, or mannitol, in particular glycerol. In one embodiment, the polyalcohol consists essentially of glycerol.

[0017] The use of glycerol, a by-product of the production of biodiesel by the transesterification of glycerides with monoalcohols, is a specific embodiment of the present invention. Suitable monoalcohols include C1-C10 monoalcohols, particularly C1-C5 monoalcohols, more particularly C1-C3 monoalcohols, especially methanol. The glycerides are mono-, di-, and esters of glycerol with fatty acids, the fatty acids generally having 10 to 18 carbon atoms. Suitable methods for producing biodiesel with associated glycerol are known in the art.

[0018] The aliphatic polycarboxylic acid used in the present invention contains at least two carboxylic acid groups, particularly at least three carboxylic acid groups. Generally, the number of carboxylic acid groups is 10 or less, more particularly 8 or less, or even 6 or less. The polycarboxylic acid has 3 to 15 carbon atoms. More particularly, the polycarboxylic acid has 3 to 10 carbon atoms. Preferably, the polycarboxylic acid does not contain N or S heteroatoms. More particularly, the polycarboxylic acid is an aliphatic polycarboxylic acid containing only C, H, and O atoms.

[0019] In one embodiment, a dicarboxylic acid is used. When used, the dicarboxylic acid can be any dicarboxylic acid having two carboxylic acid groups, generally 15 or less carbon atoms. Examples of suitable dicarboxylic acids include itaconic acid, malic acid, succinic acid, glutaric acid, adipic acid, and sebacic acid. Itaconic acid and succinic acid can be preferred.

[0020] In one embodiment, a tricarboxylic acid is used. When used, the tricarboxylic acid can be any tricarboxylic acid having three carboxylic acid groups, generally 15 or fewer carbon atoms. Examples include citric acid, isocitric acid, aconitic acid (both cis and trans), and 3-carboxy-cis,cis-muconic acid. The use of citric acid is considered preferred for both cost and availability reasons.

[0021] Where applicable, the polycarboxylic acid may be provided wholly or partly in the form of an anhydride, for example citric anhydride.

[0022] The use of tricarboxylic acids has been found to result in polyesters with attractive properties. Thus, in one embodiment, the polyacid comprises at least 10% by weight of tricarboxylic acid, whether in combination with dicarboxylic acids, other tricarboxylic acids, and mixtures thereof. In one embodiment, the polyacid comprises at least 30% by weight, preferably at least 50% by weight, of tricarboxylic acid, calculated based on the total amount of polyacid. In one embodiment, the amount of tricarboxylic acid is at least 70% by weight, more particularly at least 90% by weight, or even at least 95% by weight. In one embodiment, the polyacid consists essentially of tricarboxylic acid, where the term "essentially" means that other acids may be present in amounts that do not affect the properties of the material.

[0023] In another embodiment of the invention, the acid comprises at least 10% by weight, preferably at least 30% by weight, more preferably at least 50% by weight, of dicarboxylic acids, calculated on the total amount of acids. In one embodiment, the amount of dicarboxylic acids is at least 70% by weight.

[0024] In one embodiment, the acid comprises a combination of at least 10% by weight of a tricarboxylic acid and at least 2% by weight of a dicarboxylic acid, more particularly at least 10% by weight of a tricarboxylic acid and at least 5% by weight of a dicarboxylic acid, or at least 10% by weight of a tricarboxylic acid and at least 10% by weight of a dicarboxylic acid. In this embodiment, the weight ratio between the two types of acid can vary widely depending on the desired material properties. In one embodiment, the dicarboxylic acid comprises a total of 2 to 90% by weight of dicarboxylic and tricarboxylic acids, particularly 5 to 90% by weight, more particularly 10 to 90% by weight, depending on the desired material properties. Note that the preferred ranges for tricarboxylic acids identified above are also applicable to this embodiment. The use of tricarboxylic acids, particularly citric acid, has been found to result in the formation of high-quality composite materials, especially in combination with the use of trialcohols such as glycerol.

[0025] Without being bound by theory, the inventors believe there are several reasons why the use of triacids, especially in combination with triols, results in the formation of high quality composites. First, the use of triacids, especially in combination with triols, creates highly cross-linked polymers, resulting in increased strength.

[0026] The molar ratio of the polyalcohol to the polyacid is controlled by the ratio of the number of reactive groups in the one or more alcohols used to the number of reactive groups in the one or more acids. Generally, the ratio of the number of OH groups to the number of acid groups is 5:1 to 1:5. More particularly, the ratio may be 2:1 to 1:2, more particularly 1.5:1 to 1:1.5, more preferably 1.1:1 to 1:1.1. The theoretical molar ratio is 1:1.

[0027] Optionally, a suitable catalyst can be used for preparing the polyester. Catalysts suitable for producing polyesters are known in the art. Preferred catalysts are heavy metal-free catalysts. Useful catalysts include, but are not limited to, strong acids such as hydrochloric acid, hydroiodic acid, and hydrobromic acid, sulfuric acid (H2SO4), nitric acid (HNO3), chloric acid (HClO3), boric acid, perchloric acid (HClO4), trifluoroacetic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid. Catalysts such as zinc acetate and manganese acetate can also be used, but may be less preferred.

[0028] In one embodiment, compounds are added to increase the interaction between the polymer and hydrophobic materials or to increase the water resistance of the final product. Suitable compounds include, for example, saturated or unsaturated C5-C22 fatty acids or their salts, saturated or unsaturated C5-C22 fatty alcohols, and dimeric and trimeric fatty acids or alcohols. For example, glycerol monostearate, triethyl citrate, and valeric acid can be used in the present invention.

[0029] The compound for increasing hydrophobicity will generally be applied in an amount of 0.1 to 5% by weight, more particularly in an amount of 0.3 to 3% by weight, calculated relative to the amount of polymer.

[0030] The polyester has a degree of polymerization of 0.6 or less when present in the composition before 3D printing.If the degree of polymerization is greater than 0.6, the processability of the polyester may be reduced, and in some embodiments, an unacceptably large amount of water may be required to keep the viscosity of the composition low enough for 3D printing.The evaporation of a large amount of water may cause the composition to shrink, which may make it unattractive.It may be preferable that the degree of polymerization of the composition before 3D printing is 0.5 or less.

[0031] It may be preferred that the degree of polymerization of the polyester before 3D printing is at least 0.1, particularly at least 0.2, more particularly at least 0.25, and even more particularly at least 0.3. A higher degree of polymerization before printing ensures that less curing is required after printing, which contributes to a more efficient process. Furthermore, a higher degree of polymerization may help limit excessive interaction between the polymer and the filler.

[0032] The polymer is formed by combining the alcohol and the acid to form a liquid phase. This can be done, depending on the nature of the components, by heating the mixture of components to a temperature at which the acid dissolves in the alcohol, particularly glycerol. This can be done at a temperature of, for example, 20 to 250°C, e.g., 40 to 200°C, e.g., 60 to 200°C, or 90 to 200°C, depending on the nature of the components. In one embodiment, the mixture can be heated and mixed at a temperature of 100 to 200°C, particularly 100 to 150°C, more particularly 100 to 140°C, for 5 minutes to 2 hours, more particularly 10 minutes to 45 minutes.

[0033] The composition prior to 3D printing typically contains at least 5% by weight of polyester. If less than 5% by weight of polyester is present, the resulting molded object will not have the polyester content necessary to achieve the desired properties. It may be preferred for the composition to contain at least 10% by weight, particularly at least 20% by weight, of polyester. The composition generally contains 85% by weight or less of polyester. If more than 85% by weight of polyester is present, there will not be enough room for additional components of the composition. It may be preferred for the composition to contain 75% by weight or less of polyester, particularly 60% by weight or less of polyester, and in some embodiments, 50% by weight or less of polyester.

[0034] Filler The composition includes a solid filler. The presence of a filler is required to give the composition moldability and prevent or limit the formation of bubbles when the composition is printed. The solid filler can also give the final product certain properties, such as a desirable appearance and feel, or a particular texture. The presence of a filler can also increase the strength of the product. By selecting the density of the filler, it is possible to influence the density of the final product.

[0035] The composition before 3D printing generally contains at least 10% by weight of filler. If there is less than 10% by weight of filler, it will be difficult to form a molded object. It may be preferred that the composition contains at least 20% by weight of filler. The composition generally contains 85% by weight or less of filler. If there is more than 85% by weight of filler, there will not be enough room for additional components of the composition. It may be preferred that the composition contains 80% by weight or less of filler, particularly 70% by weight or less of filler, in some embodiments, 60% by weight or less of filler, or even 50% by weight or less of filler.

[0036] The filler used in the composition according to the present invention can be any solid material that is in a form that can be processed through the nozzle of the intended 3D printer.It will be clear to those skilled in the art that the composition of the paste to be printed must be adapted to the nozzle of the 3D printer, and vice versa.It is within the scope of those skilled in the art to perform such adaptation.

[0037] Typically the filler is a particulate material, but it is also possible to combine the use of thread-type fibers with 3D printing processes prepared for the processing of thread-type fibers, such printer nozzles being known in the art.

[0038] When particulate fillers are used, they generally have a maximum particle size of 50 mm or less, determined across their longest axis, depending on the type of material. In the context of this specification, the term "particulate" does not impose any requirements on the shape of the material. The particulate material can be fibrous or non-fibrous. If the particles are non-fibrous, they generally have a maximum particle size of 10 mm or less, determined across their longest axis, depending on the type of material. It may be preferable to use a combination of larger and smaller particles.

[0039] In one embodiment, particles are used that have an average particle size (determined across their longest axis) of less than or equal to 5 mm, in particular less than or equal to 2 mm. As a minimum value, an average particle size of 0.001 mm can be mentioned.

[0040] In one embodiment, relatively small particles are used. In this case, the average particle size is preferably 0.5 mm or less. In some embodiments, the average particle size is 0.1 mm or less, or even 0.05 mm or less.

[0041] In another embodiment, larger particles are used, in which case the average particle size is, for example, 0.5 to 5 mm, in particular 0.5 to 2 mm.

[0042] For articles with a relatively smooth surface finish, it may be preferred in part that the filler has a maximum particle size (Dv90) of 1 mm or less, especially 0.5 mm or less. For articles with a relatively rough surface finish, it may be preferred that the filler contain a fraction of particles, for example 5-50% by volume, having a particle size of at least 1 mm.

[0043] In one embodiment, the filler comprises a natural material, such as a plant- or animal-derived material.

[0044] Examples of plant-based materials include cellulose-based materials, such as virgin or post-consumer paper, virgin or post-consumer cardboard, any form of wood or other plant material, or a combination thereof. In one embodiment, a cellulose-based material derived from so-called virgin pulp, obtained directly from the wood pulping process, is used. This pulp can be derived from any plant material, but is mostly derived from wood. Wood pulp is derived from softwood trees, such as spruce, pine, fir, larch, and hemlock, and hardwoods, such as eucalyptus, poplar, aspen, and birch. In one embodiment, the cellulose-based material includes cellulose material derived from recycled paper, such as cellulose pulp obtained from recycled books, paper, newspapers, and periodicals, egg cartons, and other recycled paper or cardboard products. A particular source is the use of rejected paper fibers, which are paper fibers that are too short to be suitable for use in paper production. A combination of cellulose sources can also be used. Further examples of materials of plant origin are cotton, flax, hemp, grass, reeds, bamboo, coffee grounds, seed husks from e.g. rice, jute, kenaf, ramie, sisal, etc., and materials derived therefrom. Generally, plant material that has been ground to a suitable particle size and, if necessary, dried to a suitable moisture content may be used.

[0045] Examples of animal-derived materials include feathers, down, hair and derivatives thereof such as wool, and also bone meal.

[0046] The use of cellulose-based materials such as wood dust, wood pulp, and other cellulose-based materials such as hemp-derived dust and pulp has been found to give particularly attractive results.

[0047] Further examples of suitable fillers include ceramic fillers, including oxides such as alumina, beryllia, ceria, zirconia, silica, titania, and mixtures and combinations thereof, and non-oxides such as carbides, borides, nitrides, silicides, and mixtures and combinations thereof, such as silicon carbide. For purposes of this specification, glass is considered a ceramic material. Glass can be used in the form of, for example, short fibers, glass beads, whether solid or hollow, and ground glass particles. Suitable fillers further include micaceous fillers, calcium carbonate, and inorganic materials such as phyllosilicates. Clay, sand, and the like can also be used.

[0048] Suitable fillers also include polymer fillers such as particles or short fibers of polyethylene, polypropylene, polystyrene, polyesters such as polyethylene terephthalate, polyvinyl chloride, polyamides (e.g., nylon-6, nylon 6.6, etc.), polyacrylamide, and arylamide polymers such as aramid. Suitable fillers also include carbon fibers and carbon particulate materials. The comminuted cured polyester resin used in the present invention can also be used as a filler. The comminuted cured polyester resin containing a filler can also be used. This allows used articles according to the present invention to be recycled into new articles.

[0049] Generally, as fillers, composites can also be used, such as polymer particles provided with fillers.

[0050] Suitable additional fillers include materials that can be dissolved in the polyester composition at low concentrations, such as starch. When this type of material is used, it should be used in an amount sufficient to ensure that it is also present in solid form.

[0051] Combinations of fillers of different types and materials may also be used.

[0052] Diluent The composition suitable for 3D printing according to the present invention includes a diluent. It has been found that a diluent is necessary to ensure that the composition has an appropriate viscosity at all stages of the production process when it is fed into the 3D printer. In particular, when a substantial amount of filler is to be incorporated into the polyester, a diluent is needed to ensure effective viscosity during mixing.

[0053] A suitable diluent must meet several requirements: it must be a low-viscosity liquid; it must have no or low reactivity with the polyol and the carboxylic acid; it must be a good solvent for the polyol and the carboxylic acid; and it must evaporate easily from the composition after 3D printing. The latter point is necessary to ensure that the printed product is stable enough to retain its shape even before the printed object is subjected to a curing process.

[0054] Although other liquids are possible, the use of water is considered preferable for technical, economic, and environmental reasons. Thus, the diluent generally consists of at least 50% by weight, in particular at least 70% by weight, more in particular at least 90% by weight, and even more in particular at least 95% by weight of water.

[0055] Compositions suitable for 3D printing generally contain at least 5% by weight of diluent. If there is less diluent present, the aforementioned effects will not be obtained. The amount of diluent may be preferred to be at least 10% by weight, particularly at least 15% by weight, more particularly at least 20% by weight. On the other hand, the amount of diluent should not be too high. The amount of diluent is generally not more than 70% by weight. At higher percentages, the stability of the object obtained after printing may be insufficient unless very high printing temperatures are used. It may be preferred to use not more than 60% by weight, particularly not more than 50% by weight, of diluent.

[0056] Further ingredients The composition may include additional ingredients, such as stabilizers.

[0057] In one embodiment, stabilizers are used to improve the properties and processability of the composition prior to printing by helping to increase the interaction of the diluent, the filler, and the polyester to provide a processable material without separating the diluent from the other components.

[0058] In another embodiment, stabilizers are added to improve the properties and processability of the composition during and after printing, but before curing. In this case, the stabilizers are added to ensure that the printed composition has a suitably high viscosity under printing conditions and that the printed object has sufficient rigidity after printing, but before curing. Generally, these stabilizers increase the pseudoplasticity of the composition by binding water, polyesters, and fillers, thereby allowing the cantilever to increase the "overhang"—the extent to which the object's base can be extended—toward the object's base. Suitable stabilizers include polymers such as starch, carboxymethyl cellulose, polyethylene glycol, hydroxypropyl cellulose or carboxypropyl cellulose, hydroxyethyl cellulose or carboxyethyl cellulose, and proteins. Suitable stabilizers also include inorganic salts, such as calcium oxide, calcium hydroxide, and calcium carbonate. These inorganic salts have been found to be attractive when rapid solidification of the composition is required. On the other hand, said inorganic salts can sometimes also lead to increased brittleness of the final product depending on its further composition.

[0059] The amount of stabilizer to be added will depend on the effect to be achieved and the other components in the composition. Generally, the stabilizer will be added in an amount of 0.1 to 30% by weight, calculated relative to the weight of the starting composition before printing. If too little stabilizer is used, no effect will be observed. If too much stabilizer is used, the viscosity of the composition may become unacceptably high, and no additional beneficial effect will be obtained. Amounts of 0.1 to 25% by weight, particularly 0.5 to 20% by weight, and more particularly 1 to 15% by weight, are generally preferred.

[0060] The composition may contain additional components. Examples of additional components that may be attractive to add include pigments, dyes, and ground recycled materials according to the present invention, as discussed above. The addition of hardened particles containing polyesters derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, with or without a filler, may also be considered.

[0061] In one embodiment, a composition suitable for 3D printing is provided, comprising 20 to 50 wt. % polyester derived from glycerol and citric acid, having a degree of polymerization of 0.1 to 0.6, particularly 0.2 to 0.6. This can be combined with a total of preferably 10 to 80 wt. % filler. The filler can be selected, for example, from cellulose-containing materials such as wood pulp, wood dust, or paper fibers. The filler can be selected, for example, from glass spheres, particularly hollow glass spheres, to obtain low-density materials, or cotton fibers. Combinations of various types of fillers can also be used. The use of cured polyester particles derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, optionally containing a filler, is also attractive. The composition preferably comprises a stabilizer, in particular starch, in an amount of, for example, 0.5 to 25% by weight, in particular 1 to 20% by weight, or calcium hydroxide in an amount of, for example, 0.5 to 20% by weight or 1 to 15% by weight, which have been found to give good results.

[0062] Preparation and Use of the Composition The composition can be obtained by mixing the various components. Generally, it is preferred to prepare the polymer by first starting with a monomer solution, optionally in the presence of water, and then adding the further components. The further components can be added in a single step or in multiple steps, at the same or different temperatures.

[0063] The present invention also provides a method for preparing a shaped object, comprising the steps of: providing a composition comprising the aforementioned polyester, a filler, and a diluent; extruding the composition through a printer nozzle to form layers of the composition in a desired shape and stacking the layers on top of each other to form a shaped object; and subjecting the shaped body to a curing step during and / or after the extrusion step to form a cured shaped body. The method further comprises the steps of:

[0064] This method is also referred to herein as 3D printing.

[0065] The extrusion step involves extruding the composition through a printer nozzle, and it is within the skill of the art to adapt the viscosity of the composition to that printer nozzle, for example, by adapting the temperature of the composition or by selecting the appropriate amount of diluent or stabilizer, if present.

[0066] Since the diluent must be in the liquid phase in the composition, the minimum temperature is the melting point of the diluent.

[0067] Extrusion at elevated temperatures results in the appropriate viscosity of the composition. The extrusion process is preferably carried out at elevated temperatures, for example at least 25°C, particularly at least 40°C, as determined by the composition immediately prior to extrusion. The temperature is preferably below the boiling point of the diluent, since processing above the boiling point of the diluent can result in uncontrolled gas formation.

[0068] The temperature can be brought to the desired value by providing an air stream, in particular hot air, or by using microwave or infrared or other suitable heating means that will be apparent to the skilled person.

[0069] Depending on the temperature during the extrusion step, curing of the polymer may occur during extrusion or immediately thereafter, nevertheless it will generally be preferable to perform a separate (additional) curing step.

[0070] If desired, the molded object may be subjected to a drying step before the curing step. The drying step, generally carried out at room temperature, e.g., 15°C or 20°C to 100°C, is carried out to remove the diluent from the molded object. Drying at a relatively low temperature, e.g., below 80°C or below 50°C, may be preferred due to its low energy consumption. Drying may be carried out for, e.g., 0.1 hours to 3 days, or 0.25 hours to 3 days, depending on the size and shape of the object, the amount of water present therein, and the amount of water in the molded object. Selecting suitable drying conditions is within the skill of a person skilled in the art. The application of a vacuum may be considered to help increase water evaporation.

[0071] The curing step is intended to further polymerize the polyester. The most important aspect of the curing step is that the polyester is at a reaction temperature, for example, 80 to 250°C, particularly 100 to 200°C. Curing can be carried out using heating techniques known in the art, for example, in an oven having an oven temperature of 80 to 450°C. Various types of ovens can be used, including, but not limited to, belt ovens, convection ovens, microwave ovens, infrared ovens, hot air ovens, conventional baking ovens, and combinations thereof. Curing can be carried out in a single step or multiple steps. The curing time is 5 seconds to 24 hours, depending on the size and shape of the object and the type and temperature of the oven used. Selecting appropriate curing conditions is within the skill of a person skilled in the art. Since longer curing times may be unattractive, a curing time of 5 seconds to 12 hours, particularly 5 seconds to 8 hours, more particularly 5 seconds to 4 hours, or 5 seconds to 2 hours may be preferred. In particular, for objects having a larger size, it may be preferable to apply a temperature gradient during curing, where the temperature at the beginning of the curing process is lower than the temperature at the end of the curing process. Applying a temperature gradient can control the rate of water removal from the object, thereby helping to prevent the formation of surface unevenness. For larger objects, the above-mentioned drying process is considered preferable, as discussed above.

[0072] After curing, the degree of polymerization, as determined gravimetrically, will generally be at least 0.5, particularly at least 0.6, more particularly at least 0.7, even more particularly at least 0.8, and in some embodiments, at least 0.9. The theoretical maximum degree of polymerization is 1.0.

[0073] After hardening, the moisture content of the hardened shaped body is generally less than 10% by weight, particularly less than 5% by weight, more particularly less than 2% by weight.

[0074] The present invention also relates to a 3D printed object comprising a polyester derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, wherein the polymer has a degree of polymerization of at least 0.5, particularly at least 0.6, where the degree of polymerization is the ratio of the number of reacted functional groups to the maximum number of functional groups that can react, a filler, and generally less than 10 wt. % water.

[0075] The preferences set forth above for composition, moisture content, and degree of polymerization (the latter two for the cured body) also apply to this embodiment.

[0076] The cured article can be subjected to post-treatments known in the art, such as sanding, coating, or polishing, painting, or other surface treatments.

[0077] The present invention is suitable for providing objects for many applications, including decorative objects, furniture, etc. A particular use is in the generation of large scale prototypes. The use of 3D printing allows for custom production in a manner that is cheaper than machining a substrate and less prone to deformation than 3D printed thermoplastics.

[0078] As will be apparent to one skilled in the art, preferred embodiments of the various aspects of the invention may be combined, except where mutually exclusive.

[0079] The present invention is illustrated by, but not limited to, the following examples.

[0080] Example 1 Preparation of polyester polymer solution 1.0 kg of glycerol with a purity of >99% and 2.0 kg of citric acid (purity >99%) were placed in a stirred and heated reactor. 9 g of boric acid (0.5 m / m, >99% purity) was also added. The mixture was heated to 135°C for approximately 15 minutes and maintained at that temperature for 15 minutes, subsequently diluted with tap water to a water content of 60% and further cooled. The resulting polymer had a degree of polymerization of 0.4.

[0081] Example 2 Manufacturing molded objects using wood dust and starch A composition suitable for 3D printing was prepared as follows: 10 kilograms of polyester polymer as described in Example 1 was heated to 90°C and combined with 0.75 kg of starch and 0.75 kg of wood dust, followed by stirring. The mixture was cooled to below 50°C, and an additional 1.5 kg of starch and 1.5 kg of wood dust were added, followed by mixing.

[0082] The resulting composition consisted of 28% by weight polyester, 15% by weight starch, 15% by weight wood dust, and 42% by weight water. The degree of polymerization of the polyester remained at 0.4.

[0083] The composition was used to print shaped objects using a 3D printer. The composition was fed into the 3D printer nozzle at a temperature of 50-60°C and extruded through an 8mm nozzle at a rate of 20mm / s to a layer thickness of 3mm. Upon exiting the nozzle, the material was blown with hot air (above 200°C). The hot air blowing is intended to stimulate the binding properties of the starch.

[0084] The molded body was subsequently dried and cured in a circulating hot air oven at a temperature of 200° C. for 2 hours.

[0085] The moisture content of the hardened mass was less than 5% by weight and the mass had a degree of polymerization greater than 0.8.

[0086] Figure 1 shows the object during printing, and as can be seen, the present invention allows for the production of complex shapes in a controlled and reproducible manner, and is stable enough to allow for the printing of objects with "overhangs," i.e., portions of the object's sides that extend beyond the base surface.

[0087] Example 3 Fabrication of molded objects using wood dust, starch, and hollow glass pearls Fifteen grams of starch was mixed with 300 grams of the resin of Example 1 (containing 40% by weight of polymer and 60% by weight of water). The mixture was heated to 80°C and stirred until the starch was dissolved. It was then cooled to less than 50°C, and an additional 30 grams of starch was added. 40 grams of wood dust and 45% by weight of hollow glass pearls were added, followed by mixing. The resulting composition consisted of 28% by weight of polyester, 10% by weight of starch, 10% by weight of wood dust, 10% by weight of hollow glass pearls, and 42% by weight of water.

[0088] The degree of polymerization of the polyester was 0.4.

[0089] The mixture was 3D printed, dried, and cured as described in Example 2. The moisture content of the cured object was less than 5% by weight. The object had a degree of polymerization greater than 0.8.

[0090] The cured object is shown in Figure 2. As can be seen, the present invention allows for the production of complex shapes and is stable enough to allow the printing of objects with "overhangs," i.e., portions where the sides of the object extend beyond the base surface. The use of hollow glass pearls resulted in the formation of an object that, even though it is low density, still has a natural look and feel because it can be obtained from the use of wood dust.

[0091] Example 4 Manufacturing of shaped objects using wood dust and calcium hydroxide 30 grams of calcium hydroxide and 70 grams of wood dust were mixed. The mixture was added in portions to 300 grams of the resin of Example 1 (containing 40% by weight of polymer and 60% by weight of water), while ensuring that the temperature did not exceed 50°C. The resulting composition contained 30% by weight of resin, 7.5% by weight of calcium hydroxide, 17.5% by weight of wood dust, and 45% by weight of water. The degree of polymerization of the polyester was 0.4.

[0092] The mixture was 3D printed, dried, and cured as described in Example 2. The moisture content of the cured object was less than 5% by weight. The object had a degree of polymerization greater than 0.8.

[0093] The cured object is shown in Figure 3. As can be seen, this composition allows for the printing of complex 3D shapes with high precision.

[0094] Example 5 Production of molded objects using starch and cotton fibers Fifteen grams of starch was mixed with 300 grams of the resin of Example 1 (containing 40% by weight of polymer and 60% by weight of water). The mixture was heated to 80°C and stirred until the starch was dissolved. It was then cooled to less than 50°C, and an additional 30 grams of starch was added. 75 grams of cotton fiber and 10 grams of Aerosil (fumed silica) as a thickener were added, followed by mixing. The resulting composition consisted of 28% by weight of polyester, 10% by weight of starch, 17% by weight of cotton fiber, 2% by weight of aerosol, and 42% by weight of water.

[0095] The degree of polymerization of the polyester was 0.4.

[0096] The mixture was 3D printed, dried, and cured as described in Example 2. The moisture content of the cured object was less than 5% by weight. The object had a degree of polymerization greater than 0.8.

[0097] The cured object is shown in Figure 4. As can be seen, this composition with longer fibers results in an object with a rougher surface, allowing for the printing of complex 3D shapes.

[0098] Example 6 Fabrication of molded objects using CMC and rejected paper fibers. 300 grams of the resin from Example 1 was heated to 80°C. 75 grams of rejected paper fiber and 9 grams of carboxymethyl cellulose stabilizer were added followed by mixing. The resulting composition consisted of 31% by weight polyester, 2% by weight CMC, 20% by weight rejected paper fiber, and 47% by weight water. The degree of polymerization of the polyester was 0.4.

[0099] The mixture was 3D printed, dried, and cured as described in Example 2. The moisture content of the cured object was less than 5% by weight. The object had a degree of polymerization greater than 0.8.

[0100] The hardened object is shown in Figure 5. As can be seen from the figure, the present invention allows for the conversion of rejected paper fibers into products with attractive 3D shapes. Rejected paper fibers are a waste stream from the paper recycling industry. They contain fibers that are too short to be reused in new paper. In addition to the fibers, the fraction also contains 10-30% by weight of calcium carbonate.

[0101] Example 7 Manufacturing of large-scale objects based on hemp particles Five kilograms of water was heated to 100°C in a 25-liter planetary mixer. 0.75 kg of starch was mixed with 1 kg of hemp particles, and the mixture was added to the water. The hemp particles were a mixture of hemp shives and fibrous material, containing materials of various particle sizes, the largest being approximately 5 mm. Next, 5 kg of the resin prepared according to Example 1 was added. The mixture was stirred and cooled to room temperature. 0.35 kg of hemp particles was mixed with 1 kg of calcium hydroxide. Half of this mixture was added to the resin composition, and the mixture was stirred for 1 hour. The remaining half of the hemp and calcium hydroxide mixture was added, followed by stirring again. The resulting composition consisted of 31% by weight polyester, 10% by weight hemp particles, 8% by weight CaOH, 6% by weight starch, and the remainder water. The degree of polymerization of the polyester was 0.4.

[0102] The composition was used to print shaped objects using a 3D printer. The composition was supplied to the 3D printer nozzle at a temperature of 70°C and extruded through an 11 mm nozzle at a rate of 20 mm / s to a layer thickness of 5 mm. Upon exiting the nozzle, the material was blown with hot air (above 200°C). The blown hot air is intended to stimulate water evaporation, resulting in increased stability of the object.

[0103] The molded body was then dried and cured in a circulating hot air oven at a temperature of 160° C. for 2 hours.

[0104] The moisture content of the hardened mass was less than 5% by weight and the mass had a degree of polymerization greater than 0.8.

[0105] A photograph of the object immediately after 3D printing is in Figure 6. A photograph of the cured object is in Figure 7 (pen is for scale). As can be seen from the photograph, the object is stable and free-standing. The object had the following dimensions: height 35 cm, width 43 cm, and thickness 13 cm.

Claims

1. 1. A method for preparing a shaped object, comprising: Providing a composition, wherein the composition comprises: A polyester derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, wherein the polyester has a degree of polymerization of 0.6 or less, the degree of polymerization being the ratio of the number of functional groups that have reacted to the maximum number of functional groups that can react. solid fillers, and Diluent Including, extruding the composition through a printer nozzle to form layers of the composition in a desired shape and stacking the layers on top of each other to form a shaped object; subjecting the shaped body to a curing step to form a hardened shaped body, wherein the curing step occurs during and / or after the extrusion step; The method, comprising the steps of:

2. The method of claim 1 , wherein a separate curing step is performed after the extrusion step.

3. 3. The method of claim 1, wherein the curing is carried out at a temperature of from 80 to 250°C.

4. The method of any one of claims 1 to 3, wherein the hardened molded body has a degree of polymerization, determined gravimetrically, of at least 0.

8.

5. A method according to any one of claims 1 to 4, wherein the hardened molded object has a moisture content of less than 10% by weight.

6. 1. A 3D printed object, the 3D printed object comprising a polyester derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, a filler, and less than 10 wt. % water, wherein the polyester has a degree of polymerization of at least 0.5, the degree of polymerization being the ratio of the number of reacted functional groups to the maximum number of functional groups capable of reacting.

7. A composition for use in the method of claim 1, comprising: A polyester derived from an aliphatic polyol having 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having 3 to 15 carbon atoms, wherein the polyester has a degree of polymerization of 0.6 or less, the degree of polymerization being the ratio of the number of functional groups that have reacted to the maximum number of functional groups that can react. solid filler, Diluent The composition comprising:

8. The composition of claim 7, wherein the degree of polymerization of the polyester is at least 0.

1.

9. The composition of claim 7, wherein the composition comprises 0.1 to 30% by weight of a stabilizer.

10. 10. The composition of claim 9, wherein the stabilizer is selected from the group of polymers and inorganic salts.

11. The composition of claim 10, wherein the stabilizer comprises a polymer stabilizer selected from the group consisting of starch, carboxymethyl cellulose, polyethylene glycol, hydroxypropyl cellulose or carboxypropyl cellulose, hydroxyethyl cellulose or carboxyethyl cellulose, and proteins.

12. The composition of claim 10 or 11, wherein the stabilizer comprises an inorganic salt selected from calcium oxide, calcium hydroxide, and calcium carbonate.

13. 8. The composition of claim 7, wherein the aliphatic polycarboxylic acid comprises at least 30% by weight of tricarboxylic acid, calculated on the total amount of polyacid.

14. 8. The composition of claim 7, wherein the aliphatic polyol consists of at least 50 mole percent glycerol.

15. The composition of claim 7 comprising 20 to 50 weight percent polyester.

16. 8. The composition of claim 7, comprising a total of 10 to 85% by weight of filler.

17. 8. The composition of claim 7, wherein the solid filler is selected from one or more of a cellulose-containing material, glass spheres, and particles comprising a cured polyester derived from an aliphatic polyol having from 2 to 15 carbon atoms and an aliphatic polycarboxylic acid having from 3 to 15 carbon atoms.

18. The composition of claim 7, wherein the composition comprises 20 to 70% by weight of a diluent.

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