DE102021125715A1 - PROCESS FOR SEPARATION OF POLYMER ELEMENTS MANUFACTURED BY AN ADDITIVE MANUFACTURING PROCESS USING GRANULAR MEANS - Google Patents

Abstract

The present invention relates to a method for treating polymer elements obtained by an additive manufacturing process. The method comprises providing a treatment liquid in a chamber (1) of a device (100) and providing the polymer elements to be treated. The method further optionally includes a heating step of heating a treatment liquid to a temperature below an upper threshold temperature, the upper threshold temperature being in a range of 1°C to 80°C below the melting temperature of the polymer from which the polymer elements are formed. The method further comprises a smoothing step, wherein the polymer elements are or come into contact with the treatment liquid at a temperature above a lower threshold temperature and below the upper threshold temperature for a predetermined period of time. This occurs under conditions where the treatment liquid is in liquid form. Furthermore, the method optionally includes a cooling step for cooling the polymer elements. The present invention also relates to a device for treating polymer elements.

Description

The present invention relates to a method for the preferred treatment of polymer elements, in particular as bulk material, which were obtained by an additive manufacturing process, according to claim 1 and also a device for the treatment of polymer elements according to claim 35 or according to the preambles or generic terms of these claims. The present invention also relates to a control or regulating device.

Additive processes, also known as three-dimensional (3D) printing processes, come in different forms based on building materials in liquid, viscous, solid or powder form.

Fused Filament Fabrication (FFF) uses a continuous filament of a thermoplastic material that is applied in molten form to the growing (nascent) workpiece.

Another type of 3D printing process uses build material in powder form, which is selectively consolidated by sintering, melting, melting, or binding the powder at selected locations to create elements. These elements are built up by depositing powdered build material layer by layer.

The building material can be a polymer, metal, ceramic or composite material. One class of polymers that is useful for additive manufacturing is the class of polyamide polymers and polyamide blends, e.g. B. Mixtures. An element is formed by depositing a layer of powdered build material on a build platform and then, based on computer-generated data, selectively heating or bonding the powder in the parts of the layer that are to become part of the element. For example, the powder can be liquefied or melted by infrared radiation, sintered by a laser beam, or bonded by a binding material. The platform is then lowered, another layer of building material is added in powder form and melted, fused or glued again. These steps are repeated until the item is created.

Selective heating can be achieved by a laser beam, such as in selective laser sintering (SLS), or by infrared radiation, such as in multi-jet fusion (MJF) processes, including high-speed sintering (HSS).

A selective solidification can be achieved, among other things, by binder jetting processes. The main principle of these consolidation methods is the use of a powder which is treated to solidify at predetermined locations to give the element.

Additive sintering processes are particularly suitable for the production of elements with filigree structures, fine channels and/or complex shapes.

Building materials used in additive processes are often polymers and the quality of the elements obtained from these processes depends on the polymer used. A very desirable class of polymers for additive manufacturing is polyamide, a very tough polymer that is resistant to environmental influences and has good mechanical properties. Therefore, powdered polyamide is a useful building material and is used in Multi-Jet-Fusion (MJF), HSS and Selective Laser Sintering (SLS) processes. Other known methods use light to solidify photoreactive liquid resin, such as laser-based stereolithography (SLA) and digital light processing (DLP). Another well-known process is multi-jet modeling (MJM), in which material is heated and “trickled” onto the construction platform from nano-jets, hardened and cured with UV light.

Other materials useful in sintering processes are thermoplastic polymers such as thermoplastic elastomers such as thermoplastic polyurethane (TPU), thermoplastic polyamide (TPA), thermoplastic copolyester compound (TPC) among others.

These polymers often have an undesirably rough surface with a roughness of up to 20 μm and more.

The object of the present invention is to propose a method for increasing the surface smoothness of elements obtained by means of additive manufacturing methods.

Furthermore, a device for the treatment of polymer elements is to be specified.

The object according to the invention is achieved by a method having the features of claim 1 and by a device having the features of claim 35.

According to the invention, a method for treating polymer elements obtained by an additive manufacturing process is thus proposed. The procedure includes a Providing a treatment liquid in a chamber of a device and providing the polymer elements to be treated. The method further optionally comprises a heating step of heating a treatment liquid to a temperature below an upper threshold temperature, the upper threshold temperature preferably being in a range of 1°C to 80°C below the melting temperature of the polymer from which the polymer elements are formed. The method further comprises a smoothing step, wherein the polymer elements are or come into contact with the treatment liquid at a temperature above a lower threshold temperature and below the upper threshold temperature for a predetermined period of time. This occurs under conditions where the treatment liquid is in liquid form. Furthermore, the method optionally includes a cooling step for cooling the polymer elements.

Elements that have been produced as described above can also be treated according to the invention, for example by MJF, HSS, SLS, FFF or binder jet processes using polymer powder as the building material and an energy source such as laser or infrared radiation, heating, etc. to solidify to create a solid structure from the powder.

Examples are binder jetting processes with PMMA as the building material and a binder to produce the solid structure, or with PC, POM, PSU or PEI as the building material and an FFF process to produce the solid structure. The method of the present invention is also advantageously useful for treating elements made from thermoplastic polymer powder. Elements obtained with DLP, SLA and MJM processes can also be treated with the method of the present invention. Powder-based printing methods such as MJF, HSS and SLS are particularly suitable for the production of complicated elements with very fine structures, as the powder bed supports the elements. The elements thus obtained can be treated by the method of the present invention.

According to the invention, a device for the treatment of polymer elements obtained by an additive manufacturing process is also proposed. The device comprises a chamber with a lid, at least one container for containing the polymer elements and the treatment liquid, and means for temperature control. The device preferably also includes at least one of the following devices: a circulation device, a heating device and/or a coolant tank with a cooling fluid.

The container can have an inner container, in particular for accommodating the polymer elements.

The present invention also relates to a control or regulating device programmed to have or cause the method according to the invention to be carried out in each embodiment disclosed herein, for example by control commands to the components and/or actuators required for this purpose, in particular as disclosed herein. For this purpose, the control device can be in signal communication with the required components or can be prepared for this.

Embodiments according to the invention can have some, some or all of the following features in any combination, insofar as this is not clearly technically impossible for a person skilled in the art. Advantageous developments of the present invention are also the subject matter of the dependent claims and embodiments.

In all of the following statements, the use of the expression “can be” or “can have” etc. is to be understood synonymously with “is preferably” or “has preferably” etc. and is intended to explain embodiments according to the invention.

Whenever numerical words are mentioned herein, the person skilled in the art understands them as indicating a numerical lower limit. Provided that this does not lead to a discernible contradiction for the person skilled in the art, the person skilled in the art always reads “at least one” or “at least one” when specifying “a” or “an”. This understanding is also encompassed by the present invention, as is the interpretation that a numerical word such as "a" can alternatively be meant as "exactly one" wherever this is clearly technically possible for a person skilled in the art. Both are encompassed by the present invention and apply to all numerals used herein.

Whenever spatial information, such as e.g. B. from "top", "bottom", "left" or "right", the person skilled in the art understands the arrangement in the figures attached here and / or in the state of use. "Bottom" is closer to the center of the earth or the bottom of the figure than "above".

Advantageous further developments of the present invention are the subject matter of subclaims and embodiments.

Where reference is made herein to an embodiment, this represents an exemplary embodiment according to the invention.

If it is disclosed herein that the object according to the invention has one or more features in a specific embodiment, it is also disclosed herein that the object according to the invention expressly does not have this or these features in other embodiments that are also according to the invention, e.g. B. in the sense of a disclaimer. For each embodiment mentioned herein, the contrary embodiment, for example formulated as a negation, is also disclosed.

If method steps are mentioned here, the device according to the invention is configured in some embodiments to carry out one, several or all of these method steps, in particular if these are steps that can be carried out automatically, in any combination or corresponding devices, which preferably refer to the name of the respective Based on the method step (e.g. "determine" as a method step and "device for determining" for the device, etc.) and which can also be part of the device(s) according to the invention or can be connected to it in a signal connection, to be controlled accordingly.

When reference is made herein to programmed or configured, these terms may be interchangeable in some embodiments.

If a signal or communication connection between two components is discussed here, this can be understood to mean a connection that exists during use. This can also be understood to mean that there is a preparation for such a signal connection (wired, wireless or implemented in some other way), for example by coupling both components, for example by means of pairing, etc.

Pairing is a process that takes place in the context of computer networks to create an initial link between computer units for the purpose of communication. The most well-known example of this is the establishment of a Bluetooth connection, by means of which various devices (e.g. smartphone, headphones) are connected to one another. Pairing is also sometimes referred to as bonding.

The control or regulating device of the device according to the invention can be programmed to automatically bring about or cause individual, some or all of the method steps disclosed herein.

The terms “additive manufacturing, additive manufacturing, additive manufacturing methods” as used in the present application encompass various methods in which polymer material, in particular polymer powder, is processed into three-dimensional objects under computer control.

They include sintering as well as binder jetting or FFF processes.

They include processes in which a polymer powder is first melted, fused, sintered or bonded and then solidified at predetermined locations. It is therefore a process in which a solid element is formed layer by layer from building materials such as thermoplastic elastomers or polyamides. They also include light-induced processes such as SLA, DLP and MJM.

In particular, the term "additive manufacturing" as used in the present application encompasses a process in which a polymer powder is solidified into a predetermined shape or pattern in order to build up an object or an element, ie a component.

The term "powder-based additive manufacturing" as used in the present application refers to additive manufacturing processes that use polymers in powder form as the construction material.

The term "element" as used in the present application refers to a product obtained by additive manufacturing. Alternatively, the term "component" shall have the same or the same meaning.

An element may be made of or consist of any useful polymer, particularly a polyamide-based polymer or copolymer.

The term "polymer" as used in the present application includes polymers obtained from one type of monomer or from two or more types of monomers. It includes homopolymers, copolymers, block polymers and mixtures of different types of polymers, especially those mentioned herein.

The term "polyamide element" as used in the present application refers to an element obtained by an additive manufacturing process using polyamide or a material containing polyamide as a construction material.

The term “polyamide” as used in the present application includes a type of polyamide, a mixture of two or more types of polyamide, polyamide copolymers such as PA6/PPO and polyamide blends. It also includes polymers known as "nylon".

The term "polyamide powder" used in the present application includes one type of polyamide powder or a powder mixture of two or more types of polyamides as well as polyamide blends, i. H. Mixtures of one or more polyamide powders with other powders such as other polymer powders, metal powders, ceramic powders, fibers, etc.

The term "thermoplastic polymer" as used in the present application encompasses thermoplastic elastomers such as thermoplastic polyurethane (TPU), thermoplastic polyamides (TPA), thermoplastic polyetheramides such as PEBA, among others. The term thermoplastic polymers also includes polymers such as ABS and PEI. The term includes in particular those thermoplastic polymers or elastomers that are suitable for powder-based additive manufacturing processes.

The term "thermoplastic polymer powder" as used in the present application includes one or more types of powders of thermoplastic polymers, such as a powder of one type of such polymer or a powder mixture of two or more types of thermoplastic polymer powders as polymer blends, i.e. H. Mixtures of one or more thermoplastic polymer powders with other powders such as other polymer powders, metal powders, ceramic powders, fibers etc.

A “lower threshold temperature”, as used in the present application, is a temperature which, if exceeded, results in the element being smoothed out and/or in a preferably permanent change in the surface or the surface quality.

Smoothing can start slowly but noticeably at around the lower threshold temperature when an element is treated with a treatment liquid above the lower threshold temperature.

The lower threshold temperature may depend on the polymer of the element, the size and shape of the element, the treatment liquid, and the pressure in the treatment vessel.

An “upper threshold temperature” as used in the present application is a temperature above which the element or its geometry (particularly its computer-controlled target geometry) is at least partially distorted or destroyed; it preferably depends on the specific treatment liquid, the polymer and its melting temperature.

The upper threshold temperature is below the melting point or melting range of the polymer. The lower and upper threshold temperatures can be determined as shown below.

When a temperature is given for applying a liquid or treating with a liquid, the temperature preferably refers to the temperature of that liquid.

Applying a “liquid at x°C” means that the liquid is at a temperature of x°C and/or at least x°C when applied, and preferably further that the temperature of the liquid is maintained for the specified period of time, for example by means of heating, e.g. B. a heating bath.

The smoothing temperature mentioned herein is therefore preferably the temperature of the treatment liquid in smoothing step b) disclosed herein.

The terms "room temperature" or "ambient temperature" as used in the present application refer to a temperature of 20°C.

When the term "applying" or "application" is used in relation to treatment with a treatment liquid according to claim 1, this means that the treatment liquid is applied to the element or the element is introduced into the treatment liquid so that the element is wholly or is partially wetted or brought into contact with the treatment liquid.

This can be achieved by means known to those skilled in the art, for example by vaporizing and/or immersing the elements in the treatment liquid so that the elements e.g. B. are completely surrounded by the treatment liquid, or that selected parts of the elements are wetted by the treatment liquid.

It is preferred that the treatment liquid touches the entire surface of an element and can also flow into channels, holes, etc. or, if intended, at least cover selected portions of the surface of the element.

A period for applying the treatment liquid is the period during which the treatment liquid is in contact with the member at the predetermined temperature (or smoothing temperature) or until the treatment liquid and the member(s) are separated from each other.

Heating and smoothing periods are periods when the heating liquid or treatment liquid is at the specified temperature and in contact with the element.

The term "treatment liquid" as used in the present application refers to a liquid mixture, for example comprising water and at least one alcohol, e.g. B. a monovalent or polyvalent, z. B. aliphatic, alcohol, to treat at least one element.

A water-alcohol mixture is an aqueous mixture containing at least one monohydric or polyhydric, e.g. B. aliphatic, contains alcohol.

A water-alcohol mixture can be a combination of two or more monohydric and/or polyhydric, e.g. B. aliphatic, include alcohols.

A weight ratio of water and alcohol refers to the ratio between water and the total amount of alcohols, especially monohydric aliphatic alcohols, in the treatment liquid.

The ratio of water and alcohol is given in percent and refers to percent by weight.

A water-alcohol mixture can contain water and at least one type, e.g. B. monohydric aliphatic alcohols, in particular in the quantitative ratios given here, and optionally additional additives such as one or more other solvents, which can be, for example, aromatic alcohols, mostly in smaller amounts.

A polyhydric alcohol is an organic compound which carries at least two OH groups and can optionally have further substituents or functional groups as defined above.

Examples include glycol, glycerin, triethylene glycol, propylene glycol, ethyl diglycol, ethyl triglycol, polyethylene glycol, butyl glycol, butyl diglycol, butyl triglycol, methoxypropyl alcohol.

When “alcohol” is spoken of generally in this application, this term includes at least one alcohol as defined above and a mixture of alcohols. The term "additional solvent" as used in the present application includes a single organic solvent or a mixture of two or more solvents, which is in addition to the alcohol or water-alcohol mixture forming or in the treatment liquid as disclosed herein is present and does not comprise water or a monohydric aliphatic alcohol, although it may comprise aromatic alcohols.

Any amount of additional solvent such as polyhydric or aromatic alcohol is added in addition to the amount of treatment liquid.

Any additional solvent and/or plasticizer may be present in the treatment liquid in an amount of up to 20% by weight, for example up to 10% by weight, based on the weight of the amount of treatment liquid.

The term "plasticizer" as used in the present application refers to a compound that increases the plasticity of a material, in particular increases the flexibility of polymers, for example by reducing the attraction between polymer chains. Examples of plasticizers are aromatic esters such as phthalates, benzoates, aliphatic esters such as citrates, adipates, sebacates, cycloaliphatic esters such as alkyl cyclohexanedicarboxylates.

The term "emollient" also includes bio-based compounds such as oil-derived compounds, for example soybean oil derivatives, or essential oils such as camphor.

The term "functionalizing agent" as used in the present application refers to an agent that adds or introduces a function to the element or the surface of the element.

The function can be a chemical, physical, aesthetic, protective, etc. function.

The "solidification" of a powder can be achieved by melting, sintering, fusing, or binding a powder.

The term "chamber" as used in the present application refers to a processing chamber (also herein: process chamber or main chamber) in which the elements are processed.

The chamber can be any type of container suitable for applying a treatment liquid and preferably includes heating means, for example an external or internal microwave unit or ultrasonic unit.

The chamber may be a pressure chamber, but in some embodiments it is not. In such embodiments it has e.g. B. no lid, or does not require one.

The surface roughness of a material or element refers to the texture on the surface. It is z. B. Deviations in the profile, i. H. Deviations in a direction perpendicular to the surface, quantified.

Measured values for the profile result from scanning the actual profile with a probe. Surface defects such as cracks, scratches and dents should not be part of the profile and should not be included in the reading. Commonly used roughness parameters are R _a as the arithmetic mean roughness, where the arithmetic mean of the absolute values of the profile deviations is measured from the center line of the roughness profile, or R _z as the mean roughness depth, where the mean of i (usually i=5) profile deviations of i scan lengths are measured.

When surface roughness is mentioned in the present application, this refers to R _a values, ie arithmetic mean roughness values, unless the context indicates otherwise.

The method of the present invention involves treating elements by applying a treating liquid.

According to the invention, it was advantageously found that the surface of elements can be smoothed by applying a treatment liquid, which comprises water and at least one alcohol as defined above (i.e. monovalent or polyvalent), at a predetermined temperature and for a predetermined period of time, or the element is exposed to such a treatment liquid at a predetermined temperature and for a predetermined period of time.

The method according to the invention is suitable for the treatment of bulk material, by which is meant that several elements are treated together within the specified period of time, in particular together in a common treatment liquid, and are not separated in stages or separated by separating devices.

The method of the present invention optionally comprises at least three steps - a) a heating step, b) a smoothing step and c) a cooling step, as defined in claim 1, and may further steps such as a pre-treatment step, a post-treatment step, a functionalizing step, a vapor deposition step or include additional steps.

In some embodiments, the method does not include a heating step, in particular a heating step as described herein. In such embodiments the smoothing step is based on the presence of a treatment liquid or a mixture of or with treatment liquid and elements of desired smoothing temperature as disclosed herein, in particular for smoothing step b).

1. a) optional einen Erwärmungsschritt zum Erhitzen einer Behandlungsflüssigkeit auf eine Temperatur unter einer oberen Schwellentemperatur, wobei die obere Schwellentemperatur vorzugsweise in einem Bereich von 1°C bis 80°C unter der Schmelztemperatur des Polymers liegt, aus dem die PolymerElemente geformt werden oder wurden,
2. b) einen Glättungsschritt, bei dem die Polymerelemente mit der Behandlungsflüssigkeit in der Kammer bei einer Temperatur oberhalb einer unteren Schwellentemperatur und unterhalb der oberen Schwellentemperatur für eine vorbestimmte Zeitdauer in Kontakt stehen, optional unter Bedingungen, bei denen die Behandlungsflüssigkeit in flüssiger Form vorliegt,
3. c) optional einen Kühlschritt zum Kühlen der Polymerelemente, vorzugsweise auf eine Temperatur von mindestens 5°C unter der oberen Schwellentemperatur, besonders bevorzugt auf eine Temperatur unter der unteren Schwellentemperatur,

wobei die Behandlungsflüssigkeit Wasser und mindestens einen Alkohol, z. B. einen einwertigen oder mehrwertigen, vorzugsweise aliphatischen, Alkohol umfasst, wobei das Gewichtsverhältnis von Wasser zu Alkohol in einem Bereich von 98:2 bis 20:80 liegt.Thus, the method of treating polymer elements obtained by an additive manufacturing process, e.g. B. the following steps:

1. a) optionally a heating step for heating a treatment liquid to a temperature below an upper threshold temperature, the upper threshold temperature preferably being in a range from 1°C to 80°C below the melting temperature of the polymer from which the polymer elements are or were formed,
2. b) a smoothing step in which the polymer elements are in contact with the treatment liquid in the chamber at a temperature above a lower threshold temperature and below the upper threshold temperature for a predetermined period of time, optionally under conditions where the treatment liquid is in liquid form,
3. c) optionally a cooling step for cooling the polymer elements, preferably to a temperature of at least 5°C below the upper threshold temperature, more preferably to a temperature below the lower threshold temperature,

wherein the treatment liquid is water and at least one alcohol, e.g. B. a monohydric or polyhydric, preferably aliphatic, alcohol, wherein the weight ratio of water to alcohol is in a range of 98:2 to 20:80.

The above steps a) to c) of the method optionally take place in this order.

According to a preferred embodiment of the invention, the upper threshold temperature may be in or determined to be in a range of 50°C to 325°C, such as 80°C to 190°C.

In some embodiments of the present invention, it has been found advantageous that the use of a mixture of a monohydric aliphatic alcohol with water allows an appropriate period of time for the smoothing reaction to be adjusted.

It was also found that there is a lower threshold temperature below which no or hardly any smoothing occurs.

If, after the smoothing step b), the temperature is reduced, for example by cooling, the smoothing process becomes slower and/or stops.

Below the lower threshold temperature there is no smoothing effect, or no significant smoothing effect.

The lower threshold temperature depends on the treatment liquid, the cooling rate at which the smoothing stops, the size and shape of the elements and the polymer used from which the elements are made.

The optimal smoothing time, e.g. B. the duration of the smoothing step b), and the optimal cooling rate can be determined by routine tests.

In some embodiments of the method according to the invention, the treatment liquid preferably comprises water and at least one, preferably monohydric, preferably aliphatic, alcohol, such as ethanol, for example in a weight ratio of water to alcohol of 98:2 to 10:90, such as. 85:15 to 40:60.

In other embodiments, the treatment liquid preferably comprises water and polyhydric alcohol such as propylene glycol, for example in a weight ratio of 99:1 to 1:99, such as 70:30 to 2:98.

In other embodiments, alcohols are completely or at least mostly in pure form or consist of mixtures of different alcohols, such as pure propylene glycol or a mixture of propylene glycol and triethylene glycol and/or polyethylene glycol. Likewise, glycols can be mixed with simple alcohols such as ethanol or isopropanol as treating agents, with or without the addition of water.

In some embodiments, granular media are present in the treatment liquid. These can preferably serve as release agents and/or change the surface properties of the elements in an advantageous manner, in that the geometry of the granular media is at least partially visible on the surface through preferably plastic deformation, a mechanical material displacement on the surface of the elements is brought about or promoted and /or granular media generate material removal on the elements.

The use of granular media can reduce the sticking of the polymer elements, especially when treating bulk goods. In other words, the intensity of the smoothing can be increased, that is to say a more strongly smoothed result can be achieved without the polymer elements sticking together and/or causing pressure marks with one another and/or with respect to the container wall.

A granular medium consists of or includes many solid particles such as grains or spheres. The physics or effect of the granular media is primarily based on mechanical interactions.

In some embodiments, the granular media are made of ceramic, glass, metal, plastic, minerals such as corundum, natural substances such as nut shells, or also mixtures/compounds thereof, or they have such materials.

In some embodiments, the granular media are in spherical form.

In other embodiments, the granular media can be in any other form. For example, they can be cylinders, pyramids or cuboids.

In certain embodiments, the granular media may have sections in the shape of spheres, cylinders, pyramids, cuboids, or other shaped sections.

In some embodiments, the size, such as B. length, width, diameter, the granular media from about 0.1 mm to about 30 mm, preferably their size is between 0.4 mm and 12 mm.

Larger diameters or edge lengths than about 0.1 mm are particularly advantageous because they do not tend to stick within the softened polymer surface and therefore do not remain permanently in or on the polymer element.

Granular media no larger than approx. 30 mm have proven to prevent or star ken reduction of sticking proven to be particularly advantageous.

In some embodiments, the granular media are of different sizes and/or different shapes and/or are made of different materials.

In some embodiments of the method according to the invention, the treatment liquid is mixed with the polymer elements and the granular media, at least temporarily.

In some embodiments, the mixing takes place in the form of flow and/or sound or ultrasound and/or vibration and/or possibly other forms such as pressure changes.

In some embodiments, the granular media serve not only to reduce possible sticking of polymer elements but also to microstructure the polymer elements. To put it another way, the geometries of the granular media or parts thereof stand out on the surface of the polymer elements. As the polymer elements soften during the smoothing process, these effects can become progressively more pronounced. If the treatment temperature is subsequently reduced and the surfaces are hardened as a result, these microstructures can become permanently visible.

In certain embodiments, the structuring of the surface of the polymer elements can optionally be a separate, additional treatment step. Depending on which surface finish is to be achieved, this can be brought about in a targeted manner through the appropriate choice of granular media in connection with parameters such as time and temperature as well as the intensity of the circulation. Alternatively, for example if no surface structures are primarily to be produced, the treatment liquid, with or without granular media, can preferably be used as a pure release agent by selecting the parameters differently accordingly.

In some embodiments, an additional effect on the color of “off-white” polymer elements, such as by fabrication using MJF or HSS, can be achieved.

For example, MJF elements have a black coloration on the inside and are preferentially gray or white on the surface due to the bulk processing without granular media. The polarity of the granular media can cause more mixing at the surface, making the elements more black. This is preferably the case with granular media with non-polar properties. Granular media with strongly polar properties can strengthen the effect of gray or white coloring.

In some embodiments, the granular media can be used simultaneously or in a preferably preceding process step for depowdering of the polymer elements, i. i.e. R. before the actual smoothing. The powder residues should preferably be filtered out. At the same time, it is advantageous that the granular media preferably have a particle size of approximately greater than 0.2 mm, particularly preferably greater than 0.4 mm, so that they are not filtered out like the residual powder, but are preferably not sucked in by the pump in the first place. The residual powder usually has a particle size of approx. 0.05 mm.

In some embodiments of the method according to the invention, before the smoothing step b), the elements are subjected to at least one heating and/or steaming step in an upper section of the chamber in which the smoothing step b) takes place or will take place, which is filled with gas, via a predetermined Minimum duration reserved.

The minimum duration can be from about 30 seconds to about 12 hours. This depends heavily on what is to be achieved, e.g. B. elements can preferably only be preheated or z. B. with water (steam) are saturated. Alternatively or in addition, physical changes to the surface, such as an inward shift of carbon black, can already be achieved in this pre-treatment step.

When using z. B. with water / ethanol as the treatment liquid, the elements can be saturated with protective water (steam) and they can thereby be brought to the higher temperature in less time than without the use of steam. During the actual smoothing, such a water retention can ensure that the softening of the surface is less severe and thus deformation of e.g. B. thin contours less effective and / or elements less prone to sticking.

In these embodiments, the system is preferably designed in such a way that the treatment liquid does not completely fill the chamber, here also: process chamber, so that there is a gas area in the upper part of the chamber, in which the polymer elements remain before the actual treatment process. During chamber temperature control, a preferred vapor phase is created in the chamber due to the possible evaporation of the solvents, depending on the pressure the polymer elements can be pre-treated and/or pre-tempered before they are introduced into the treatment liquid.

In some embodiments, the gas pressure, preferably nitrogen pressure, is controlled or adjusted in an upper portion of the chamber during the vapor deposition step. Preferred values range from 1 bar (atmospheric pressure) up to about 20 bar, or from 1,000 hPa to 20,000 hPa.

The composition of the gas phase can preferably be controlled with the precise control of the gas pressure, which is introduced into the process chamber as process gas.

In some embodiments, the vapor deposition step corresponds to the heating step a) or it temporally overlaps with it.

In some embodiments, the treatment results can be optimized and/or the treatment time of the polymer elements in the treatment liquid can be reduced by the pretreatment or preheating.

With little or no additional gas pressure at the beginning of the heating phase of the treatment liquid, ethanol can evaporate from approx. 78°C and water from approx. 100°C, or azeotropic phases in a temperature range in between. The resulting amount and concentration of steam and/or the steam ratio can be adjusted and controlled at least to a certain extent by targeted regulation of the gas pressure in the process chamber. Mixing of any predominant vapor phases, i.e. areas in which there are different vapor concentrations and/or temperature windows, can be achieved by suitable devices such as propellers, which are preferably positioned on the top of the boiler, and/or other drive means such as sound waves and/or other devices for assisted gas circulation can be achieved.

In this configuration, the polymer elements are at least preferably or partially in the gas or steam zone and are specifically pre-treated and pre-tempered there.

In some embodiments, the water in the treatment liquid is or will be completely or partially replaced or replaced by glycerol, a glycol, in particular a propylene glycol, a polyethylene glycol or a triethylene glycol.

In some embodiments, polymer elements are preferably de-powdered in connection with granular media, for example by means of circulation, by means of pressure fluctuations, by means of ultrasound and/or by means of sound waves.

In some embodiments, the depowdering can be carried out by combining granular media with liquid treatment agents, preferably consisting of alcohols and/or water.

In some embodiments, the depowdering can be carried out as a pre-treatment step and/or combined with the smoothing step

Here, for example, an ethanol-water mixture can put the residual powder adhering to the polymer elements in a kind of greasy state (soap-like) from approx. 50°C (depending on the concentration). In this state, most of the residual powder does not come off statically, but it can be better detached by additional mechanical/physical processing such as vibratory grinding and/or blasting, preferably in connection with granular media and/or by blasting with a liquid treatment agent. The depowdering can be done in combination with granular media, e.g. B. by means of ultrasound or vibration, as well as without additional media in the treatment agent, i.e. with pure ethanol/water or isopropanol/water (rliquid additives).

Pressure differences in the chamber by actively increasing or decreasing the gas pressure inside the chamber can provide an additional depowdering effect. The reason for this can be the change from compression to expansion in general. A second explanation for stronger depowdering in relation to the chamber pressure or gas pressure can be the fact that at a gas pressure below the treatment agent vapor pressure in relation to the current temperature of the treatment agent, vapor bubbles form within the treatment agent (i.e. it starts to boil). and these ensure additional kinetic energy on the surface of the polymer elements, which can better remove residual powder.

This gas pressure, preferably nitrogen pressure, can be used in the bulk material process in order to pretreat polymer elements in the gas area or in the vapor phase with water or alcohol-water and/or to bring them to a specific temperature level as uniformly as possible.

Alternatively or additionally, the polymer element properties, the strength of the in some embodiments through the targeted introduction of treatment agents during circulation Smoothing and the possible bonding of polymer elements are advantageously specifically influenced. If a flow is chosen for the introduction which circulates the contents of the chamber in an annular flow, then there is good heat distribution from the chamber wall when it is heated. If at least part of the flow is selected from below for an upward flow direction, a buoyancy is generated in relation to the polymer elements, i.e. counteracts gravity and at the same time a higher degree of mixing/circulation of the polymer elements can be achieved (annular flow and upward flow through pump circulation). .

Here, the term "upflow" describes a flow that is preferably brought about in a targeted manner or an at least partially exercised movement of the treatment agent and/or the granular media and/or the elements in a direction that is within a chamber at least in sections and at least approximately from below extends above. An “upflow” can be achieved, for example, by the directional flow of a pump, in that the outlet of the pump is at least mostly directed from the bottom up within a chamber.

The term "annular flow" describes a flow that is preferably brought about in a targeted manner or an at least partially exerted movement of the treatment agent and/or the granular media and/or the elements in a direction that is at least in sections and at least approximately circular, spiral or extends helically, i.e. at least partially exerts a rotational movement, which i.a. can be influenced by the shape of the container wall of the chamber. An “annular flow” can be achieved, for example, by the directed flow of a pump in combination with a container wall, in that the outlet of the pump extends at least partially and approximately in a tangential direction to a housing or container wall.

In some embodiments, a device is provided for measuring the surface smoothness of the elements present in the chamber, or at least one of them. This facility can B. be or include an optical measuring device. It can be a mechanically acting device, or combinations thereof. So e.g. For example, a sharp object can be provided, which as a test pushes into one of the elements, while its surface becomes increasingly softer as a result of the progressive smoothing. The depth of penetration of the tip of this object into the softened surface can be determined optically or in some other way and allow conclusions to be drawn about the extent of the smoothing that has already taken place. Target parameters, an evaluation scale, reference values, reference images etc. can be provided and stored in advance for a conclusion, e.g. B. in the control device or a data or image memory connected thereto.

In some embodiments, a camera and/or an optical microscope and/or an infrared measuring device can be provided for checking or monitoring the smoothing.

In some embodiments, the device is provided with a plurality of reservoirs for or with treatment liquid, or receptacles therefor.

In some embodiments existing reservoirs for or with treatment liquid can be marked in different ways, e.g. B. with QR codes for automatic recognition.

In these embodiments, provision can additionally be made for storage containers that are preferably marked in this way to be replaced by the device, preferably independently, e.g. B. after a certain number of smoothing cycles, over which the treatment agent may have changed, z. B. in its concentration and / or in the consistency. Several reservoirs can therefore be provided, they can be kept separable or not permanently connected. The preferably automated change between the contents of different storage containers with different treatment liquids, or which have at least individual components of the treatment liquid, can take place, for example, via valves which can represent different fluidic connections within the device, such as multi-way valves.

In some embodiments at least one sensor is provided for determining the concentration of the treatment liquid. Provision can also be made to adapt the concentration of the treatment liquid, in particular as a reaction to sensor feedback, and/or the smoothing parameters during and/or between the smoothing steps of subsequent smoothing cycles or batches.

In some embodiments, at least one filter is provided in or on the device, in particular for the filtration of suspended matter and/or detached powder or polymer particles in or out of the chamber. Such filters can be, for example, coarse screens and/or fine screens or other filter media such as filter paper, filter sponge or filter floss. Any other filter medium known to those skilled in the art is applicable bar. The filter medium can be used during operation, for example by introducing it into the flow circuit of a circulating pump, which circulates the treatment liquid before, during and after smoothing. A suitable filter unit can also be implemented in a separate flow circuit, which is primarily provided only for filtering the treatment agent. A filter can be arranged in order to clean the treatment agent which may be contaminated with particles.

Some embodiments provide for the collection of measurement data. The measurement data can, for example, be or include values for temperature, pressure, treatment agent concentrations or the like. A measurement of polymer element characteristics such as surface quality, surface roughness, surface hardness, flexural rigidity, tensile strength, compressive strength or other polymer element measurement data known to those skilled in the art within the construction chamber before, during and after the treatment steps can also be provided.

In certain embodiments, an evaluation of the parameter or parameters can result in an adjustment in the process of temperature, pressure, times, concentration, heating rates, cooling rates, temperature-time behavior.

In some embodiments, a reference polymer element can be provided for the measurement, such as e.g. B. a test stick, a pull rod, a cuboid or other, in which such forms are used. In particular, internal contours such as bores and/or channels, preferably of reference polymer elements, can also be equipped with such measuring instruments. The reference polymer elements have the advantage that no usable polymer elements are damaged by the measurements and at the same time these reference polymer elements preferably represent standardized shapes and geometries, which means that such measurements can always be directly compared with one another over time, as can such data can be compared and adjusted with other systems and/or at other locations. Such reference polymer elements are preferably manufactured in SLS, MJF, or HHS processes together with the polymer elements to be smoothed in order to be able to measure the parameters exerted on the polymer elements to be smoothed during printing, such as the state of the raw material/powder, e.g. B. aging, the exact temperature data in the construction process and other data or their effect and/or to be able to integrate them as far as possible into the measurement and/or adjustment of the smoothing. Such reference polymer elements may be coded on the surface to enable them to be archived for backup with unique assignment.

In some embodiments, the device has a signal connection to other devices of this type and/or to an evaluation device, or a signal connection can be prepared for this. Such a connection or network can be used for analyzing and/or adjusting the treatment parameters of one or more of the interconnected devices.

In some embodiments, an emergency power system or a battery system is provided in or on the device. With it, at least the necessary maintenance of the control for status control and / or to activate an emergency program after a power failure can be done, valves for protective gas and / or other valves should z. B. can still be switched even after a power failure, cooling liquid can be circulated with a pump at least to the extent necessary, and / or a valve is opened so that, for example, tap water can be pumped through the cooling system of the system by its own pressure.

The method of the present invention can be useful for any element obtained from a polymeric material by an additive manufacturing process.

In certain embodiments, the at least one additional solvent is selected from substituted or unsubstituted aromatic C ₆ -C ₁₂ alcohols, polyhydric alcohols selected from glycerol and glycols, esters, ethers, ketones, lactones and DMSO or mixtures thereof, the solvents preferably being DMSO or γ-Butyrolactone, and / or wherein the plasticizer is selected from aromatic esters, aliphatic esters, cycloaliphatic esters, bio-based compounds, wherein the plasticizer is preferably at least one of phthalates, benzoates, citrates, adipates, sebacates, cyclohexanedicarboxylic acid alkyl esters, fatty oils, essential oils.

In some embodiments, a variety of polymeric elements can be treated in the same process.

In particular, the method of the present invention can be applied to any element obtained by an additive manufacturing process from a polymeric material which has been smoothened as desired by the treatment liquid of the present invention at the application temperature of the treatment liquid (herein also: smoothing temperature) is softened and/or dissolved.

Polymers that are used in additive manufacturing processes are known to those skilled in the art.

Examples of polymers that can be used as a building material for an element are thermosetting or thermoplastic polymers. Materials that are particularly useful in powder-based additive manufacturing processes are thermoplastic polymers such as polyamides and thermoplastic elastomers. Examples of suitable polymers and polymer classes are polyamide, acrylates such as polymethyl methacrylate (PMMA), polyoxymethylene (POM), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polyether block amide (PEBA), polycarbonates (PC), polyethylene furanoate (PEF), polyurethanes such as thermoplastic polyurethane (TPU), polysulfone (PSU) such as polyethersulfone (PESU) and polyphenylsulfone (PPSU), polyetheretherketone (PEEK), polyetherketone (PEK), polyimide, polyetherimide (PEI), styrene polymers and copolymers such as acrylonitrile butadiene styrene (ABS), acrylonitrile Styrene acrylate (ASA) or triblock polymers of polystyrene and poly(ethylene oxide) blocks (ABA) or a thermoplastic polymer of polyetherimide and polycarbonate available as Ultem 9085 or copolymers, blends or blends of any of the above materials.

Furthermore, elements based on photopolymers such as acrylates can also be treated with the method according to the invention, i. H. Elements obtained with processes such as Stereolithography (SLA), DLP or other light-based processes such as Polyjet or Multijet. It has been found that the method of the present invention can also be used advantageously for this type of polymers when the treatment step is carried out before or between sub-steps of an optional post-curing.

The method of the present invention is particularly useful for elements obtained from polyamide-based polymers and copolymers.

Polyamide is used in different versions. Suitable polyamides are aliphatic, partially aromatic and aromatic polyamides, for example polyamide 12 (PA12), polyamide 6 (PA6), polyamide 6.6 (PA6.6), polyamide 11 (PA11), PA 4.6 (PA4.6), polyamide 612 (PA612) , Polyphthalamide (PPA) or thermoplastic co-polyamides or mixed or filled polyamides such as a mixture with metal powder, for example a mixture of aluminum powder and polyamide powder available as Alumide, or polyamide powder filled with particles such as glass particles or copolymers, mixtures or mixtures thereof . It has been shown that PA12 or filled PA12 is particularly suitable for a method as described and claimed.

Elements that can be smoothed with the method of the present invention can be, for example, those made as described above by MJF, HSS, SLS methods using polyamide powder as a construction material and an energy source such as laser or infrared radiation to a solid structure from the powder, binder jetting methods using PMMA as a build material and a binder to create the solid structure, or using PC, POM, PSU as a build material and an FFF method to create the solid structure, or by light-induced processes - such as MJM. MJF, HSS and SLS are particularly suitable for the production of complicated elements with very delicate structures, since the powder bed carries the elements.

Elements obtained by granulate extrusion or pellet extrusion can also be treated with the method of the present invention.

According to the invention, the elements are treated with a treatment liquid. This contains at least one and can contain two or more monovalent or polyvalent, e.g. B. aliphatic alcohols and / or other solvents and / or additives.

It has been found that a treatment liquid comprising a water-alcohol mixture as defined in the claims or disclosed herein is useful to treat the surface of elements obtained by additive manufacturing, in particular to smooth the surface and optionally properties such as color, gloss, structure, adhesion, anti-adhesion, electrostatic charging, electrical conductivity and/or to functionalize the surface or parts thereof. Depending on the polymer to be treated, one or more alcohols can be used in liquid form.

Suitable alcohols are especially aliphatic C ₁ - C ₁₀ - alcohols.

Examples of aliphatic C ₁ -C ₁₀ alcohols which are highly suitable as treatment liquids include ethanol, isopropanol, propanol, n-, iso- or tert. butanol, methanol or any mixture thereof. Ethanol is a monohydric alcohol used for the method of the present invention is very suitable.

According to a preferred embodiment of the invention, the treatment liquid may comprise water and ethanol in a weight ratio of 98:2, or 95:5, to 10:90 and/or the treatment liquid may be applied at a temperature ranging from 120°C to 180°C are under the conditions where the treatment liquid is in liquid form.

In some embodiments, the treatment liquid is or includes propylene glycol. Water may or may not be added to the propylene glycol. At least one (further) alcohol may or may not be added to the propylene glycol.

Propylene glycol without the addition of water smoothes the following polymers in particular by immersion: PA12 from approx. 145°C, PA11 from approx. 145°C, TPU (preferably TPU01 from BASF) from approx. 100°C.

80% propylene glycol with 20% volume units of water smoothes the following polymers in particular by immersion: PA12 from approx. 150°C, TPU (preferably TPU01 from BASF) from approx. 115°C.

80% propylene glycol with 20% polyethylene glycol 400 (glycerine can also be used as an additive instead of polyethylene glycol 400, with slightly poorer properties on the surfaces and tend to have higher treatment temperatures) smoothes the following polymers in particular by immersion: PA12 from approx. 150°C, TPU (preferably TPU01 from BASF) from approx. 115°C.

• - Es können 5°C bis 40°C höhere Glättungstemperaturen als bei Ethanol bzw. Isopropanol erforderlich sein (sowohl in reiner Form, als auch in Verbindung mit Zusätzen wie Wasser bzw. Polyethylenglykol oder Glycerin bei Konzentrationen vorzugsweise bis zu 50%),
• - Zusätze wie Wasser oder auch andere, möglichst für den Glättungsprozess weniger aktive bzw. weniger reaktive, Lösemittel wie Polyethylenglykol oder auch Glycerin können die Glättungstemperatur ähnlich wie Wasser erhöhen und können eine Art Blocker während der Abkühlphase darstellen, können also auch die untere Schwellentemperatur bevorzugt auf ein höheres Temperaturniveau setzen.

Depending on the application, the use of propylene glycol during smoothing can have the following properties:

• - Smoothing temperatures that are 5°C to 40°C higher than with ethanol or isopropanol may be required (both in pure form and in conjunction with additives such as water or polyethylene glycol or glycerine at concentrations preferably up to 50%),
• - Additives such as water or other solvents that are less active or less reactive for the smoothing process, such as polyethylene glycol or glycerin, can increase the smoothing temperature in a similar way to water and can represent a kind of blocker during the cooling phase, so they can also preferably lower the threshold temperature set a higher temperature level.

In some embodiments, the treatment liquid is pure or nearly pure propylene glycol (up to 95% by weight). Propylene glycol can thus be used in pure or almost pure form without the corresponding additives such as water or other inactive liquid substances for smoothing by dipping or in bulk.

In some embodiments, a mixture of propylene glycol and triethylene glycol can be used as a treatment liquid preferably for treating TPU01 from BASF at temperatures from 100°C to 140°C.

In some embodiments, the treatment liquid can be selected from at least one treatment agent such as glycerol, isopropanol, ethanol, propylene glycol, polyethylene glycol, triethylene glycol, diethylene glycol, ethylene glycol, ethyl diglycol, ethyl triglycol, polyethylene glycol, butyl glycol, butyl diglycol, butyl triglycol, methoxypropyl alcohol, ethyl acetate, methyl acetate, butyl acetate, amyl acetate , acetone, butanone, iobutanol, 1-butanol, benzyl alcohol, γ-butyrolactone, propylene carbonate, 1,3-butanediol, 1,4-butanediol and water, or the like.

It was advantageously recognized that the smoothing effect of the treatment liquid used according to the invention can in some cases be improved by adding at least one plasticizer and/or at least one additional solvent.

Therefore, for those elements that are difficult to smooth or that would require high temperature and/or pressure, the addition of at least one plasticizer improves the results of smoothing and can reduce the temperature and/or pressure to be used.

Plasticizers are known to those skilled in the art.

Preferably, those that are non-toxic are used.

Plasticizers that are compatible with the polymer used to make the elements are particularly useful. Examples of plasticizers are aromatic esters, aliphatic esters, cycloaliphatic esters and bio-based compounds such as phthalates, benzoates, citrates, adipates, sebacates, alkyl cyclohexanedicarboxylates, fatty oils and essential oils.

The plasticizer is used in an amount effective to enhance the desired effect. An amount of 0.1 to 20% by weight, such as 1 to 10% by weight, for example 2 to 7.5% by weight, based on the total weight of the treatment liquid may be used.

Furthermore, the treatment liquid can contain at least one additional solvent to improve the smoothing effect.

Without being bound to a theory, it is assumed that the additional solvent has the function of a solubilizer, ie supports and promotes the smoothing effect of the alcohol. Therefore, the additional solvent can be a solvent that is compatible with the polymer used to make the element and the water-alcohol mixture. Solvents found useful may be selected from substituted or unsubstituted C ₆ -C ₁₂ aromatic alcohols, polyhydric alcohols selected from glycerol and glycols, esters, ethers, ketones, lactones and DMSO or mixtures thereof, the solvent preferably being DMSO or γ-butyrolactone .

The amount of the additional solvent depends on the tolerability and the effect.

It can be as little as 0.5% by weight or less and up to 20% by weight, for example up to 10% by weight.

It has been shown that when plasticizer(s) are added to the treatment liquid, the lower and/or upper threshold temperature can be reduced by up to 10° C., while the upper threshold temperature can be increased by adding, for example, a polyhydric alcohol such as glycerol. Sometimes it makes sense to increase or decrease the threshold temperatures to match the crystallization temperature of the polymer.

The method of the present invention preferably comprises at least three steps as previously described.

The treatment time of an element depends on various factors such as material, shape and size of the element to be treated, type of treatment liquid, applied temperature and pressure, surface roughness of the element to be treated, and others.

In the heating step a), the treatment liquid comprises the polymer elements to be treated and is in contact with them during the heating, or the heating step a) comprises that the treatment liquid is heated at least to the lower threshold temperature, up to the upper threshold temperature or above, and that the Polymer elements are heated separately in an aqueous solution to a temperature below the upper threshold temperature, and wherein for or in step b) the treatment liquid and the polymer elements are brought into contact for smoothing.

In the heating step a), the treatment liquid and optionally the polymer elements are preferably heated to a temperature below the temperature used for smoothing.

In one embodiment, treatment liquid and polymer elements are heated together so that smoothing does not begin, i. H. to a temperature below the lower threshold temperature.

As a result of this pre-treatment, the components are saturated with the treatment liquid or possibly with water or, in the case of shorter times, only superficially saturated. At the same time, the components (as homogeneously as possible and, if possible, also in the core of the component) are brought to a higher temperature. This way there can be less distortion from smoothing.

For this embodiment, in step a), the treatment liquid with polymer elements is preferably heated to a temperature in the range from 80° C. to 170° C., preferably over a period of 5 seconds to 24 hours.

In another embodiment, the treatment liquid is heated separately from the polymer elements and added to the polymer elements only for or only at the smoothing step.

In this embodiment, the treatment liquid can be heated to a temperature between a lower threshold temperature and an upper threshold temperature, or even higher, as the temperature of the liquid decreases upon contact with the elements. Both embodiments have advantages. When the liquid and elements are heated together, the process is simple. When liquid and elements are heated separately, the process is more flexible and energy can be saved.

According to a preferred embodiment of the invention, the heating step a) can be carried out at a temperature ranging from 40°C to 200°C for a period from 5 seconds to 24 hours.

According to another preferred embodiment of the invention, in the smoothing step b) a temperature above the lower threshold temperature and 1°C to 30°C below the upper threshold temperature can be maintained for a period of 1, 2 or 3 seconds to 300 minutes.

In smoothing or related to smoothing step b), there are two critical points: the upper threshold temperature and the lower threshold temperature.

Both temperatures can be determined by one skilled in the art as described below. When treating the polymer elements, care must be taken to ensure that the elements are not exposed to temperatures that exceed the melting point of the polymer from which the elements are made. Therefore, the upper threshold temperature is below the melting temperature, at least 1°C below, and may optionally be in a range of 1°C to 150°C, such as 1°C to 80°C below the melting temperature. The upper threshold temperature is specific to the treatment liquid/polymer combination used in the process. It is the temperature above which the element is at least partially deformed or destroyed. This is the upper limit for the smoothing step. The lower threshold temperature is the temperature for a particular treatment liquid and polymer at which smoothing begins. This temperature can be determined as described below. Thus, the smoothing step b) is carried out at a temperature which is between the lower threshold temperature and the upper threshold temperature and is preferably close to the upper threshold temperature, for example 1°C to 30°C, such as 2°C to 15°C, normally 2 °C to 10°C below the upper threshold temperature.

The lower the temperature and the closer it is to the lower threshold temperature, the longer the time needed for smoothing. Smoothing times greater than 15 minutes are less preferred as longer treatment times can result in element destruction and risk of lower quality. Time periods in the range of 10 seconds to 10 minutes, such as 20 seconds to 5 minutes have been found to be preferred. The closer the treatment temperature is to the upper threshold temperature, the faster the smoothing response and the shorter the smoothing time. The upper threshold temperature is specific to each treatment liquid and polymer combination and also depends on the apparatus and conditions used for the smoothing process.

The smoothing of the polymer elements cannot be carried out at a temperature above the melting point of the polymer since the elements would be destroyed immediately.

However, good results can be obtained at a temperature slightly below the melting point of the polymer. Thus, the upper threshold temperature is in a range of 1°C to 80°C below the melting point and can be determined for a specific combination of treatment liquid and polymer. A temperature range suitable for a water-ethanol mixture as a treating liquid for treating polyamide members is 120°C to 170°C under conditions where the treating liquid is in liquid form.

To determine the upper threshold temperature, polymer elements are brought into contact with a treatment liquid at a predetermined temperature for 30 seconds or up to 2 minutes and then immediately cooled.

Typical cooling rates are between 1°C/minute to 60°C/minute. The elements are then analyzed. If the elements were destroyed or the surface shows signs of deterioration, the treatment was above the upper threshold temperature and the test is repeated at 5°C, 1°C and 2°C below the previously applied temperature. If the element has an intact surface, the test can be repeated at a slightly higher temperature, e.g. B. 1°C or 2°C higher. The upper threshold temperature is determined or determined with just a few experiments.

Determining the upper threshold temperature can be part of the method according to the invention, as can determining the lower threshold temperature.

Alternatively, the determination of the upper threshold temperature precedes the method according to the invention. The result of this determination can be used when executing the method according to the invention.

The lower threshold temperature is the other critical temperature for the process of the present invention.

The lower threshold temperature is the temperature at which smoothing begins. It is specific to each combination of polymer and treatment liquid and can be determined as follows. Elements obtained by additive manufacturing from a specific polymer such as polyamide are contacted with a treatment liquid having a predetermined composition, for example a combination of ethanol and water with a ratio of ethanol to water of 60:40. The treatment liquid in contact with the members is heated to a temperature under conditions where the treatment liquid is in liquid form, and this temperature is controlled for a predetermined one Duration of time, for example 1 to 10 hours, such as 2 to 6 hours. After this specified period of time, the elements are cooled and examined to determine whether smoothing has taken place. If the elements show no and/or slight signs of smoothing, the test temperature is below the lower threshold temperature. With slight signs of smoothing, the temperature is near or at the lower threshold temperature.

As mentioned above, the lower threshold temperature is the temperature at which smoothing begins. In other words, items can be stored in the treatment liquid for a long time provided the temperature is below the lower threshold temperature. It can be advantageous to store the elements to be treated for some time, for example 5 minutes to 24 hours, for example 15 minutes to 10 hours, in particular 30 minutes to 5 hours, in the treatment liquid at an elevated temperature but below the lower threshold temperature. On the one hand, it can be advantageous if the elements to be treated are already at a temperature close to the smoothing temperature. On the other hand, it has been found that pretreating elements at a temperature below the lower threshold temperature either with the treatment liquid or with water or with a mixture of water with a lower amount of alcohol can be advantageous in order for the surface of the elements to be saturated with water. This can increase the buffering function of the water when smoothing, i. H. delay a reaction that would otherwise proceed too quickly or may destroy the elements.

Without being bound by theory, it is believed that particularly favorable results can be obtained when the upper threshold temperature is in the range of the crystallization temperature of the polymer.

It appears that the smoothing process achieves the best results when smoothing occurs around the crystallization temperature of the polymer. As can be seen in the examples, experiments were carried out with polyamide, preferably PA12 (PA2200), with a crystallization temperature between 135°C and 150°C. When using a treatment liquid comprising, for example, 40% ethanol and 60% water, it has been found that the upper threshold temperature when using a polyamide and providing conditions such that this treatment liquid is in the liquid state is 148°C. Polyamide elements were treated with this treatment liquid for a period of about 10 to 20 seconds and then cooled. A surface with an R _a of 1 μm to 5 μm can be obtained.

The smoothing process and the quality of the elements obtained can in many cases be further optimized by a preheating step, by monitoring and controlling the cooling time and optionally by post-treatment.

It has been found that the period of time that the elements are in contact with the treatment liquid at a temperature below the lower threshold temperature is not critical, in the sense that the elements can be kept in the treatment liquid for up to 48 hours without damage gain weight.

The period of time that the elements in the treatment liquid spend at temperatures above the lower threshold temperature is critical.

Once the temperature is above the lower threshold temperature, the smoothing process begins, slow at first and becoming very fast as the temperature gets closer to the upper threshold temperature. The length of time to keep the elements in contact with the treatment liquid at a temperature between the lower threshold temperature and 1°C to 15°C below the upper threshold temperature depends on the heating rate and can be adjusted. Preferably, this can be maintained over a period of 1 second to 20 minutes.

In this temperature range, depending on the size and shape of the elements, in particular the presence of channels, holes, internal cavities, etc., the heating can take place very quickly, quickly or slowly.

Smoothing occurs very quickly near the upper threshold temperature. Therefore, the period of time to hold the elements in a temperature range between 5 and 0.5°C below the upper threshold temperature should be in the range of up to 2 minutes, preferably 5 seconds to 1 minute, such as 10 to 30 seconds. The smoothing time depends on the wall thickness and element size and is longer for larger parts and shorter for small parts. The length of time also depends on the heating rate during heating. The smoothing period can be up to 30 minutes, for example 1 second to 15 minutes, and is preferably about 20 seconds to 10 minutes. The higher the heating rate, the shorter the smoothing time.

In addition, it was found that the contacting of the elements to be treated with Water or with the treatment liquid in a pre-treatment step can improve the smoothing results.

Since such contacting below the lower threshold temperature tends not to be critical, the time range tends not to be critical. Without being bound by theory, it is believed that by maintaining the elements at a temperature below the lower threshold temperature for some time, e.g. at least 30 minutes, e.g. 1 to 24 hours in water or in a water-alcohol mixture, the Allows elements to absorb or imbibe water on their surface. The water absorbed or soaked into the outer surface layer of the elements can act as a buffer, adjusting the smoothing effect of the alcohol, which can be very strong, so strong that it can destroy elements when the temperature is above the upper threshold temperature. Therefore, to optimize the quality and finish of the elements, a pre-treatment step can be an option. This step can be performed at any temperature below the lower threshold temperature, for example 20°C to 100°C. This pre-treatment step can also be used to “pre-heat” the elements and/or the treatment liquid and can thus help speed up the smoothing step.

Another parameter of the method is the heating rate of the elements in step a) and/or step b).

In step a) the heating is not critical and many variants are possible. More critical is the heating rate in smoothing step b), if there is one, as it affects the smoothing time and the quality of the elements. Typical heating rates when heating elements in or together with the treatment liquid, ie preferably in the smoothing step b), are 0.5° C./min to 30° C./min, such as 2° C./min to 10° C./min.

Once the smoothing period is complete, the elements are optionally cooled in step c).

In some embodiments, smoothing step b) involves heating, e.g. B. from about the lower threshold temperature (or below) to a desired temperature value that is below the upper threshold temperature.

In some embodiments of the method according to the invention, in cooling step c), the polymer elements are cooled to a temperature of at least 5° C. below the upper threshold temperature, preferably to a temperature below the lower threshold temperature.

Using the treating liquid of the present invention, in preferred embodiments, smoothing can stop very quickly when cooling starts, i. H. when the elements or the treatment liquid are cooled to a temperature of preferably more than 5°C below the upper threshold temperature. Without being bound by theory, it is believed that the surface of elements is saturated with water, which acts as a buffer and prevents alcohol from reacting outside of the smoothing temperature or 5°C below. Since the smoothing reaction is delayed and more or less stopped as soon as the temperature is 5°C below the upper threshold temperature, the smoothing period can be determined or adjusted very precisely, so that optimal smoothing can advantageously be achieved.

According to a preferred embodiment of the invention, in cooling step c), the treatment liquid with the smoothed polymer elements can be cooled for a period of 1 minute to 48 hours and/or the treatment liquid can be at least partially replaced by a cooling fluid, the cooling fluid preferably being water.

In general, it has been found that using the treatment liquid of the present invention, the temperature range for smoothing is between 50°C to 320°C, such as 120°C to 180°C. A preferred temperature range is 100°C to 190°C. As already mentioned, this temperature range depends on the composition of the treatment liquid and the polymer from which the elements are made. When the relative amount of alcohol is high, the smoothing activity of the treatment liquid is high and the upper threshold temperature is lower. When the relative amount of alcohol is small, the active part of the treatment liquid is small and water weakens the activity. In this case, the upper threshold temperature is higher. If the treatment liquid is applied over a longer period of time, the element softens, contours can become blurred or sensitive parts or channels can be destroyed.

As stated above, it is considered that the upper threshold temperature is preferably in the range of the crystallization temperature of the polymer of the element to be treated.

Depending on the material of the elements, the most suitable treatment liquid can be identified. Some examples are detailed below. The shape of the item must be taken into account, since filigree structures are more sensitive to handle than simple structures such as cubes. For complex structures, it may be preferable to use short treatment times. A feature with many channels, holes, or cavities may take longer to smooth the entire surface, while a small feature and/or a simple shaped feature may require smoothing, e.g., within a few seconds to about a minute. In addition, the application time also depends on the initial surface roughness.

For example, elements obtained by SLS typically have higher initial surface roughness than elements obtained by MJF or HSS. Therefore, the time to obtain smooth surfaces can be longer for SLS elements than for MJF elements.

The method of the present invention can be carried out in any known apparatus suitable for contacting elements with a liquid. When using a chamber with a microwave device and/or ultrasound device, for example, the conditions can be adjusted accordingly.

After treatment, the elements can be removed from the chamber and dried or functionalized in a further step.

Drying can be achieved by placing the smoothed elements in an oven or dry box, optionally using means such as a fan or other known means to remove any remaining treatment liquid. The drying time is not critical and can be from about 5 minutes to hours or even days such as 1 to 24 hours. Alternatively or in a combination of times, the drying can also be carried out in a vacuum oven and/or in a vacuum chamber with or without additional heat input and/or with a circulating device. Such devices can be part of the device according to the invention.

In some embodiments, at least one functionalizing agent is applied to the polymer elements during or after treatment with the treatment liquid in at least one step of the method.

In some embodiments, at least one functionalizing agent is applied during or after step c), the method preferably further comprising a step d) for functionalizing the smoothed polymer elements by applying at least one functionalizing agent.

In some embodiments, means for driving the treatment liquid and/or the functionalizing agent are used during at least one of steps a) to c) and/or during the functionalization step d), the driving means preferably being at least one impeller, a propeller, a Vibration unit or an ultrasonic unit is.

In some embodiments, the functionalizing agent comprises at least one agent selected from a colorant, a dye, a pigment, a fiber, a curing agent, a metal powder, a polymer powder (preferably a polyamide powder, a polypropylene powder, a TPE powder, a PET powder, a PETP powder, a PBT powder), an inorganic pigment or powder, an electrostatic discharge agent, a filler, a base, an acid, a buffer system, a finisher and/or a plasticizer.

In some embodiments, a colorant or a dye solution is applied in the functionalization step d).

In some embodiments of the method according to the invention, the polymer elements were obtained by a sintering/melting process, such as by multi-jet melting, a multi-jet fusion process (MJF), laser sintering (SLS) or a high-speed sintering process (HSS), a binder jet process, a ceramic or metal binder process, a light-based process such as SLA, DLP, Polyjet or Multijet or a filament manufacturing process.

In some embodiments, the polymer of the polymer elements is selected from a polymer or copolymer based on polyamide, a thermoplastic elastomer such as thermoplastic polyurethane (TPU), thermoplastic polyamide (TPA), thermoplastic copolyester compound (TPC), or thermoplastic styrene block copolymers (TPS), such as Styrene/ethylene/butylene/styrene block copolymer (SEBS) or acrylic polymers such as acrylonitrile-butadiene-styrene (ABS), acrylester-styrene-acrylonitrile (ASA) or one of PMMA, POM, PC, PEI, ULTEM9085, PSU, PESU, PPSU , PPS, PEK, PEAK, PEEK, PEKK or polybutylene terephthalate (PBT) or a copolymer or a mixture thereof.

In some embodiments, the polymer of the polymer elements is a polyamide selected from an aliphatic, semi-aromatic or aromatic polyamide such as polyamide 12 (PA12), Polyamide 6 (PA6), Polyamide 6.6 (PA6.6), Polyamide 11 (PA11), PA 4.6 (PA4.6), Polyamide 612 (PA612), Polyphthalamide (PPA); a thermoplastic polyamide or copolyamide, or a blended or filled polyamide, or copolymers, blends, or blends thereof.

In some embodiments of the method, the treatment liquid is applied until the surface roughness of the polymer elements is reduced by 1 μm to 20 μm.

The treatment of polymer elements by the method of the present invention can be carried out in any suitable apparatus.

The polymer elements can be used, for example, in a device as claimed in the present application and as in 1 shown to be treated, comprising a chamber or process chamber with an optional lid, at least one inner container for containing the polymer elements and the treatment liquid, and means for temperature control, the device preferably further comprising at least one of a circulating device, a heating device and/or a coolant tank , which comprises a cooling fluid. This device is described and explained in more detail below and in the example.

A chamber, such as a pressure vessel, may be used to apply the water-alcohol mixture, for example a water-ethanol mixture.

The chamber is equipped with a lowerable platform for positioning the elements. The elements can be arranged in any form, for example the elements can be suspended under the platform by means of suspension means and/or can be arranged on a platform, for example as bulk material in a perforated or slotted container or on a grid. In the following, options for component-specific storage and the different clamping and suspension variants are described. The advantage is that using a treatment liquid of the present invention allows the members to flow and they can be treated without sticking to each other.

To circulate the treatment liquid, it can be useful to use a stirring device such as a distributor, an impeller or a turbulator.

Devices suitable for stirring or stirring, such as stirring rods, impellers, etc., are known to the person skilled in the art. Any agent used in an apparatus or method of the present invention must be chemically resistant to the treatment liquid and should withstand the temperatures used, for example in excess of 170°C when the upper threshold temperature is high.

Control mechanisms are known to those skilled in the art and may be electric, pneumatic, hydraulic, or some other type of drive.

The platform with the elements remains in the treatment liquid for the set process time.

Some embodiments of the present invention are outlined above and/or below.

Each described step can be combined with other embodiments as long as there is no contradiction and the context allows it.

It is also possible to supply liquids to two or more containers within the chamber.

These containers are preferably open at the top. A liquid is, for example, the treatment liquid for smoothing the elements at elevated temperature, for example a water-ethanol mixture. The second liquid can be a process retardant or an inert solvent such as glycerin or water, or a functionalizing agent such as a colorant or dye. A mechanical manipulator such as a gantry crane can be provided to transport the items between the two containers according to the process description.

The method of treating elements according to the present invention may further include steps of functionalizing the elements.

At least one functionalizing agent can preferably be applied to the polymer elements in at least one step during or after the treatment with the treatment liquid. At least one functionalizing agent can particularly preferably be applied during or after step c), in which case the method can preferably also include a step d) for functionalizing the smoothed polymer elements by applying at least one functionalizing agent.

During at least one of steps a) to c) and/or during the functionalization step d), means for driving the treatment liquid and/or the functionalizing agent can be used, which is Drive means is preferably at least one impeller, a microwave unit or an ultrasonic unit.

The functionalizing agent may comprise at least one agent selected from a colorant, a dye, a pigment, a fiber, a curing agent, a metal powder, a polymer powder, an inorganic pigment or powder, an electrostatic discharge agent, a filler, and others. Base, a finishing agent and/or a plasticizer.

A colorant or dye solution can preferably be applied in the functionalization step d).

It has been found that by controlling process temperature and process time, mechanical or dynamic properties of polymer elements treated with the method of the present invention can be altered in a controlled manner, such process control can also affect the microsurface or the options for post-treatment processes.

A matt surface with very smooth surface values can be produced by appropriate process control. In the post-treatment of the elements such as coating, galvanizing, gluing or other post-treatment steps, a process carried out in this way can bring advantages in terms of adhesion, by, among other things, reducing the surface tension of the polymer element surface for the respective process.

In most cases, an element is treated with treatment liquid in such a way that the entire surface comes into contact with treatment liquid and is thus smoothed.

If only a part, or section, of an element is to be smoothed, only this part may come into contact with the treatment liquid. This can be achieved by excluding the part of the element which is to remain untreated from contact with the treatment liquid and/or by protecting it from contact with the treatment liquid, for example by applying a protective layer to the part of the element which is to be untreated remains, for example by applying a layer such as a layer of wax or a layer of silicone, in particular a peel-off layer.

Another benefit has been found for elements that contain carbon black and therefore have a black or gray finish and are difficult to color. Due to the process, carbon black is contained in elements that are obtained, for example, through an MJF or HSS process or in elements that are formed in special SLS processes. It appears that a polar liquid such as water or a salt solution, for example an aqueous solution containing 1 to 20% by weight of a salt such as NaCl or Na ₂ CO ₃ , is imbibed by the elements and carbon black inside or out of the displaced inside the element. The surface becomes whitish or light gray and can be colored more easily and efficiently than black or dark gray elements.

In particular, whitening occurs at a temperature above the crystallinity temperature of the polymer. Thus, in one embodiment, polymer elements obtained by additive manufacturing that include carbon black can be treated with water or an aqueous salt solution at a temperature ranging from 130°C to 175°C.

Even better, elements with a white or light gray surface treated by the process of the present invention can be colored since the surface is smooth after treatment, but not dense or compressed.

The elements can be colored in a known manner with any of the types of dyes used to color such polymers. When a dye soluble in the treatment liquid is used, smoothing and coloring can be performed in one step. When a dye is not soluble in the alcohol used as a treating liquid, a solubilizer for the dye, such as an organic solvent, may be added.

It has been found that treatment of elements containing carbon black with salt, such as table salt, as described above can generally be used to improve color.

This step can be performed without a smoothing step or process, or with or after other smoothing processes.

Examples of dyes useful in the method of the present invention are acid dyes, basic dyes, reactive dyes, sulfur dyes, disperse dyes, metal complex dyes, etc. and mixtures thereof.

The elements can be colored in hues, nuances, tints and shades.

The elements obtained by treatment according to the present invention have a smooth surface that hardens and is mechanically strong and can be of any color, such as white or black, or a tint that can be obtained by coloring if desired.

These elements can be used as is, they can be stored until use, or they can be further treated with a functionalizing solution to improve or change the properties and/or to make the surface of the element harder or shinier to make them more brilliant or textured. It has been found that elements treated by the process of the present invention can be dyed at lower temperatures than prior art elements, for example less than 100°C, and still obtain a brilliant, uniform surface. In addition, it has been found that when coloring elements of the present invention, less dye is required and no pressure is required. Without being bound by theory, it is believed that when mechanical means are used to smooth a surface of an element, densification or closure of pores and cells at the surface may occur while the surface of elements finished by the process of have been smoothed according to the present invention are not compacted. Therefore, elements smoothed by the process of the present invention accept dye more easily from a dye solution, no pressure or high temperatures are required, and the surface accepts the dye even when the dye solution is not oversaturated.

As a result, good and reproducible results can also be achieved with less concentrated dye solutions.

In addition, smoothing and coloring of elements can be carried out simultaneously or independently in any order, which advantageously makes the method according to the invention very versatile.

In one embodiment elements are first smoothed and then colored, in another embodiment elements are first colored and then smoothed. Coloring can be done in the same process line as smoothing, or elements can be smoothed, stored and colored if desired or required. Thus, coloring and smoothing can be performed independently.

Elements, particularly white elements, treated by the process of the present invention have a smooth surface that can be tinted using conventional staining techniques. These elements can be colored in many different tones due to their smooth white surface, which has not been densified by mechanical treatment.

If a powder-based manufacturing process was used to fabricate the elements, a key advantage of the process provided by the present invention is that the surface is smooth and contains little or no powder as any powder left on the surface after additive manufacturing , is removed or melted or fused by the treatment according to the invention.

Another advantage is the mechanical strength, especially the fatigue strength of the elements.

Without being bound by theory, it is believed that by treating elements with the method of the present invention, interfacial stresses are reduced and molecular chains are rearranged or restructured, resulting in a smoother and stronger surface.

The process of the present invention allows not only smoothing but also functionalization of elements to improve their properties such as gloss, texture, mechanical strength, electrical properties such as electrostatic charge, etc.

This will e.g. B. achieved by contacting the elements with a functionalizing agent together with the treatment liquid or directly after treatment with the treatment liquid while the surface of the element is still soft.

A functionalization solution or agent can be applied to the element either together with the treatment liquid or to the element obtained after application of the treatment liquid.

A functionalizing agent is any agent that imparts positive properties such as appearance, color and/or texture to the surface.

A functionalizing agent can provide a hard and/or glossy surface, a deep black surface or a surface in a desired shade, a special structure of the surface, a metallized surface, the can optionally be post-galvanized, i.e. a primer layer for galvanizing, or a surface that avoids electrostatic charging. The functionalizing agent may also include fibers, powders, or other reinforcing agents that can result in either a reinforced layer and/or a textured layer. It is also possible to use a plasticizer as a functionalizing agent to provide a smooth and soft surface. These functionalizing agents can be used in a manner known to those skilled in the art, ie, at concentrations, at temperatures, and for times typically employed for such agents. The method of the present invention makes it possible to use such functionalizing agents and to provide functionalized surfaces in a simple manner. Thus, the method of the present invention is very versatile and allows the creation of different surfaces.

For application, the functionalizing agent can either be dissolved in the treatment liquid containing water and at least one alcohol and optionally an additional solvent, or dissolved in another solvent and applied together with the treatment liquid.

It is also possible (ie included as an embodiment of the present invention) to apply a solution of the functionalizing agent shortly after the smoothing step, for example within 1 to 20 minutes after the smoothing step. It is also possible to apply a functionalizing agent in powder form, either dispersed in the treatment liquid or as a separate dispersion together with the treatment liquid or after application of the treatment liquid, while the surface of the element is still soft or tacky. For example, a dispersion of treatment liquid and powdered functionalizing agent can be used.

It has been found that when using a powder, for example a metal powder, there is the possibility of using an evaporation chamber with a microwave unit and/or an ultrasonic unit for the solvent vapor contacting step.

In particular, metal powders with particles in the nanometer range can be distributed in high density and with high uniformity using microwaves and/or ultrasonic waves. Microwaves and/or ultrasonic waves ensure that the resulting steam smoothes the surface and distributes the functionalizing agent very evenly. Another possibility is to apply functionalizing agent in liquid/liquid/dispersed form together with or after treatment with treating agent. For example, the functionalizing agent can be provided in liquid form in a container and the elements can be immersed therein.

Because the process of the present invention results in elements with a smoothed surface without densifying the surface layer, these elements can be dyed with good results with acid dyes, disperse dyes, sulfur dyes, or other dyes known for dyeing polymers used in additive manufacturing processes are used, such as polyamide.

Thus, a high quality colored and smooth surface is obtained. Examples of dyes suitable for dyeing polyamide are C.1.. Acid Red dyes, C.I. Acid Blue Dyes, C.I. Acid Yellow Dyes, C.I. Acid Black Dyes, C.I. Acid Orange dyes or mixtures thereof such as C.I. Acid Red 1 , C.1. Acid Red 138, C.1. Acid Red 52, C.1. Acid Blue 40, Nylason Red N-2RBL or mixtures thereof. The acid dyes can be used, for example, in a concentration of 0.01% by weight to 7.5% by weight. Since the elements obtained by the treatment according to the invention have a smooth surface without mechanical compaction, the temperature for coloring can be lower than for elements obtained with prior art processes. For example, it has been recognized that dyeing can be carried out at a temperature of from 40°C to 130°C. The staining time can range from 10 to 180 minutes.

In general, after the treatment steps a) to c) have been completed, the element is removed from the device and dried.

Any remaining liquid should be removed and the polymeric element can be dried as known in the art, for example by simply leaving the polymeric element in the air or by heating, using an air stream or jet stream or any other means commonly used for drying polymeric elements.

The method of the present invention smoothens the surface of elements obtained by an additive manufacturing process using building material in powder form, the elements having a roughness R _a of the surface of the elements before treatment in the range of up to 20 µm, such as 1 µm to 15 µm.

By treatment according to the present invention, the elements can be smoothed to reduce roughness by up to 15 µm, such as 5 µm to 10 µm, such that the roughness after treatment is in the range of up to 10 µm, e.g 0.3 µm to 6 µm, for example 1 µm to 4 µm. According to a preferred embodiment of the invention, the treatment liquid can be applied until the surface roughness of the polymer elements is reduced by 1 μm to 20 μm.

A further reduction in roughness can be achieved by more than one treatment pass.

The smoothing effect can be achieved with or without mechanical pre-treatment. In addition, the method according to the invention has further advantages, since the steps can be carried out easily and can be at least partially automated.

In a further embodiment of the present invention, a mechanical step can be carried out after the elements have been treated with the treatment liquid while the surface of the elements is still soft.

In some cases, treatment with glass beads or jet stream and/or open air plasma can further smooth the surface.

The method of the present invention may optionally include a further step - a post-processing step in which elements which have been treated with a treatment liquid are contacted with a post-processing composition which may be a colorant such as water or an aqueous solution, immediately or up to 25 minutes after treatment.

Contact with water or an aqueous solution ensures rapid solidification of the surface, thus avoiding sticking of elements and damage to the surface. The composition of the aqueous solution is not critical as long as it does not adversely affect the elements or their surface. A suitable aqueous solution is, for example, a mixture of water and a polyhydric alcohol, such as a mixture of 1% by weight to 25% by weight of a polyhydric alcohol and water. A suitable polyhydric alcohol is, for example, diethylene glycol, water can be distilled water. The temperature of the finishing composition is not critical. The ambient temperature can be suitable and most comfortable. In other embodiments, a sub-ambient temperature may be useful. It has been found that the result can be improved by using water or an aqueous solution with a temperature ranging from 0°C to 20°C.

Post-processing of elements obtained after the smoothing step by drying in an oven or by using vacuum for drying can further improve the result.

Glyols, i.e. dihydric alcohols, can preferably be used to smooth PA12, PA11, PA6 and TPU (others are also possible).

In some embodiments, the treatment liquid contains or consists of a mixture of glycol and water, such as propylene glycol and water, preferably in the ratios to one another specified here for the ethanol-water mixture.

In some embodiments, the treatment liquid contains or consists of a mixture of propylene glycol and triethylene glycol or polyethylene glycol. Other glycols, or glycols that are preferably passive or less reactive at the same treatment temperatures on the surface of the elements, can also be used for or as the treatment liquid.

The advantage of using treatment agents such as at least one glycol as a complete or partial replacement for, for example, ethanol and/or water is the higher boiling point of the treatment liquid or the individual ingredients of the treatment liquid, which is preferably above the treatment temperature in smoothing step b) (for example up to 170°C ) lies. In this way, a complex pressure vessel is not required. The method according to the invention and/or its smoothing step b) can be carried out in an open chamber or in a chamber that is not necessarily pressure-tight.

The (glycol) processes described can all be combined with the granular media already described in the treatment liquid. Such granular media as an additive in the treatment agent can serve as a release agent during smoothing and/or for microstructuring and/or for an additional, mechanical smoothing process.

In some embodiments, the treatment liquid is or will be placed in a container, e.g. B. in a kind of capsule, before treatment preferably in the required amount for a treatment brought. The capsule is placed in the chamber, as are the elements.

In the heating step, the chamber is heated, for example to a value between 100°C and 200°C. At the same time or after the chamber has been heated up, the air is optionally sucked out of the chamber. A negative pressure or vacuum can be generated or a certain amount of protective gas can be introduced into the chamber, e.g. B. to displace the air, or after evacuating the air from the chamber.

In some embodiments, provision is made for the capsule to be actively heated with the treatment liquid in whole or in part independently of the temperature control of the chamber and the elements. In a preferred embodiment, the temperature achieved or aimed for in this way is higher than that of the chamber or of the elements. If the capsule has a certain volume, the treatment liquid can at least partially evaporate in the capsule after it has been heated up and is at least no longer exclusively in liquid form.

Are the predetermined smoothing temperature and the predetermined pressure reached, the capsule is opened with the treatment liquid or the vapor formed therefrom, which z. B. can be done magnetically. The no longer liquid treatment agent can then spread as a vapor in the chamber and flatten the elements. This condition is then preferred for a predetermined period of time, e.g. B. held 5 to 10 minutes. Then the vapor is optionally evacuated by a pump and/or the temperature of the chamber and hence the elements is optionally (preferably rapidly) lowered. Due to the cooling step configured in this way, the smoothing process stops and smoothing step b) is thus ended.

In a preferred embodiment, there are multiple containers, e.g. B. capsules with possibly different amounts of treatment liquid in the chamber or in fluid communication with it. In this way, the smoothing can be carried out in a number of partial smoothing steps one after the other, so to speak, in a pulsed manner. The capsules can not only contain different amounts of treatment liquid, but these different amounts can have different temperatures, which can also apply if the amounts should be the same.

Water can be used to cool or otherwise stop smoothing. This can e.g. B. be provided in one of the containers or capsules mentioned here.

In some embodiments of the device according to the invention, this is prepared for carrying out the method according to the invention.

In some embodiments, a container for additives is placed in the chamber of the device according to the invention.

In some embodiments, the additive container is filled with colorants (e.g., liquid or as a powder), pigments, functionalizing agents (e.g., as a powder or with fibers), or with additives.

In some embodiments, a reservoir containing warmer or colder treatment liquid is in fluid communication with the chamber of the device according to the invention, or the device is prepared accordingly.

In certain embodiments, the reservoir can be filled with a warmer or colder treatment agent, e.g. B. by 5 °, 10 °, 15 °, 20 ° C or more, for faster heating or cooling in the chamber, herein also referred to as the main chamber, be or are filled. Alternatively or additionally, it can be connected to a circulating pump and/or be pressurized.

When smoothing bulk goods, the treatment agent in the chamber is brought to the treatment temperature within a maximum heating rate. This happens, for example, at 1°C/min up to 5°C/min. If the heating rate is to be faster (no longer approximately linear), then when circulating by means of a circulating pump, additional stored treatment agent from a storage container, which has been brought to an even higher temperature in advance, can be introduced into the chamber from a certain temperature or increased by circulating be at least partially exchanged in this way. This means that the treatment agent can be heated up much more quickly.

Conversely, when cooling down (preferably directly after the temperature inflection point), colder treatment agent can be brought from the storage container into the chamber by circulation. In this way, the treatment agent can be cooled more quickly in the upper (critical) temperature range.

The method described can preferably be combined with other methods for heating or cooling. So e.g. B. during cooling, in addition to the solution just described, cooling hoses on the housing wall also provide an additional cooling effect.

In some embodiments of the device, the fluid connection is operatively connected to a circulating pump and/or a means for pressurizing.

In some embodiments, the reservoir is or will be filled with treatment agent that has been preheated to or above the predetermined treatment temperature. The elements are stored in the main chamber. For smoothing, the preheated treatment agent or at least part of it is conducted or conveyed from the reservoir into the main chamber. This can be done in various ways, such as by using at least one pump (for suction or pressure) and/or by applying pressure (compressed air/protective gas) in the reservoir and/or in the main chamber. In certain embodiments, the pressures can be specifically set and/or pulsated in this way, that is to say pressure fluctuations between the chambers or containers can be provided in order, for example, to accelerate the detachment of residual powder from the components.

In some embodiments, the cooling preferably takes place via at least one built-in cooling coil, cooling surface or the like.

In some embodiments, a colder treatment agent is forced into the chamber by pressure. In these embodiments, either the internal pressure then increases further, or the increasing pressure in the chamber is continuously released via a pressure relief valve.

Before entering the chamber, a smaller amount of water is optionally added to the chamber and preheated to approximately the upper treatment temperature. The water will evaporate from approx. 100°C and thus wet and infiltrate the polymer elements as water, whereby the water can serve as a protective medium in depth during smoothing.

In some embodiments, the inner container can be fixed in the container, preferably in a detachable and/or adjustable manner.

In some embodiments, the inner container is provided for accommodating the polymer elements within the chamber, in particular in order to be able to be removed from the device, for example upwards, preferably without tools.

In some embodiments, the inner container, which can be a basket, is preferably made of stainless steel and/or it is preferably coated with a coating that reduces the adhesion of at least partially melted elements.

Suitable coatings are, in particular, those which have an easy-to-clean effect. They preferably withstand the process temperatures. Such coatings are preferably formed from PTFE, PFA, ceramics, microfinish and/or other materials or polymers which can reduce adhesion of polymer elements during smoothing.

In some embodiments, the inner container preferably has a mesh size of 1 mm to 10 mm. It preferably has square or rectangular openings between 1 mm×1 mm and 10 mm×10 mm, or circular openings with diameters between 1 mm and 10 mm.

In some embodiments, the inner container is preferably designed in the form of a cylinder.

In some embodiments, the inner container particularly preferably has a partition for the polymer elements in the center of the cylinder, e.g. B. in the form of another cylinder. In other words, such a preferred inner container has approximately the shape of a ring when viewed from above.

In some embodiments, the inner container by means such. B. dividers or partitions in several segments (pieces of cake) are divided.

In some embodiments, the inner container is, particularly preferably, manufactured in the center with a geometry that has a driver option for a rotational movement in relation to a drive shaft that is preferably vertical within the chamber.

In some embodiments, the tang is most preferably in the shape of a triangle, in others it is a square, and in still others it is a hexagon.

In some embodiments, the inner container has a diameter to height ratio of from about 5:1 to about 1:1.

In some embodiments, the volume of the inner container that can be used to accommodate polymer elements is preferably between 10 liters and 60 liters.

In some embodiments, the inner container is designed with a lid, which is preferably provided for the polymer ments to be completely submerged after being immersed in the treatment liquid.

In some embodiments, the lid of the inner container is a basket lid.

In some embodiments, the lid of the inner container is, particularly preferably, designed with geometries or structures which, by rotating the inner container, cause a forced flow of the treatment agent from top to bottom, in order to actively press down polymer elements with a low density within the treatment liquid. Such geometries can B. represent recesses, projections and / or machine elements, which approximate the form and function of propellers.

In some embodiments, the device according to the invention is intended to accommodate several inner containers in one chamber.

In these embodiments, the inner containers are optionally such that they can be stacked on top of one another.

Alternatively, the inner containers are formed in the form of cylinder segments, which preferably, but not absolutely necessary, form a closed cylinder after being assembled within the device.

In some embodiments, the device has devices, preferably below the region of the chamber cover, with which the inner container can be rotated in order to mix the polymer elements. Such facilities can B. cylinder and / or telescopic cylinder, chains and the like. Elongated machine elements, which preferably have one or more joints, also fall under such devices within the meaning of the present invention. Particularly preferably, at least one arrangement of machine elements is used for the preferred mixing of elements, which arrangement is similar to a scissor lifting mechanism.

In some embodiments, the chamber has a chamber passage for an axial and/or rotary drive of the at least one inner container and/or for at least one impeller, preferably for circulating the treatment agent.

In some embodiments, the chamber leadthrough is preferably designed in the form of a circular shaft, which particularly preferably has a diameter of 8 mm to 22 mm.

In some embodiments, the wave-like chamber leadthrough is optionally designed as a tube, with the interior of such a tube preferably being sealed off from an increased chamber pressure.

In some embodiments, the chamber leadthrough is designed as a tube and has at least one further corrugation in its center in order to generate a double leadthrough in this way. This embodiment can be advantageous if, in addition to at least one up and down movement of the inner container, a rotating movement of the at least one impeller is to be carried out, which is preferably located in the axial direction near the container bottom on its inside.

In some embodiments, a wave is preferably passed through the bottom of the chamber and at least approximately in its center, preferably at least approximately coaxially to the chamber wall, which is preferably designed in the form of a cylinder. Such a shaft preferably has a geometry on its upper side which represents a form-fit driver connection with respect to the at least one inner container.

Alternatively or in addition, the shaft can also be provided with another mechanism on its upper side, which serves as a kind of quick-release fastener compared to the inner container and is designed in such a way that it permanently withstands the special conditions within the smoothing process.

In some embodiments, the shaft is optionally driven by drive elements, which are preferably arranged below the chamber or below the chamber floor and are connected to the chamber from the outside by appropriate devices, in such a way that such drive elements have as little thermal action as possible through the Experience heating of the chamber.

In some embodiments, at least two drive elements are preferably arranged below the chamber floor, with a first drive element providing for an axial movement of the shaft (up and down) and a second drive element for a radial rotary movement of the shaft.

In some embodiments, the drive element for the linear and/or axial movement of the shaft is optionally a spindle axis, a scissor lift mechanism, a pneumatic cylinder, a hydraulic cylinder or other machine element known to those skilled in the art for imparting linear movement.

In some embodiments, the rotational movement is preferably exerted by an electric motor, which is preferably attached to the axially movable part of the linear drive element.

In some embodiments, the shaft can also be introduced into the chamber from above. This is preferably the case when a surface treatment is carried out with treatment agents whose maximum treatment temperatures are below their boiling points.

In some embodiments, the rotational movement of the shaft and the at least one inner container connected thereto is carried out during the treatment process at different speeds, which alternate cyclically or continuously between a speed of preferably 1 rpm and 250 rpm. In addition, the rotary movement can also be stopped completely, at least temporarily.

In some embodiments, the direction of rotation of the inner container can be cyclically reversed in order to bring about an optimal mixing of treatment agent and polymer elements.

In some embodiments, an up and down movement between two or more end points can be performed simultaneously or alternately with changing speeds and/or directions of rotation.

In some embodiments, the speed and cyclic frequency of the up and down movements can be varied.

In some embodiments, the shaft is preferably sealed relative to the chamber by means of shaft sealing rings or O-rings, which are preferably arranged in at least two rows, so that at least double protection against leakage of treatment liquid is effected.

In some embodiments, high pressures of up to 20 bar prevail within the chamber during the process. In order to reduce such pressure loads on the shaft sealing rings or on the O-rings and/or to ensure greater security against the escape of treatment agent, a cavity can be created on the side of the shaft passage(s) or O-rings opposite the chamber pressure be designed in the form of a machine element which can be subjected to an overpressure of gas, preferably an inert gas and particularly preferably nitrogen. The overpressure in this cavity can range from atmospheric pressure to the internal pressure of the chamber or preferably up to 10 bar above it. Such a machine element designed as a cavity is designed in a manner known to those skilled in the art and can be equipped with additional shaft bushings and/or O-rings.

In some embodiments of the device according to the invention, a magnet bushing, e.g. B. in the center provided.

In these embodiments, no opening into the chamber is advantageously necessary instead of a passage with shaft and sealing ring.

In some embodiments, a magnet receptacle is provided into which the magnet referred to herein can be inserted or from which it can be removed. The magnetic recording can, for. B. as a wall of the chamber inverted, be designed from the outside loadable structure whose interior is not in fluid communication with the interior of the chamber. When the magnet is inserted inside the structure, it can also be wholly or partly inside a cross-section of the chamber, but without being in fluid communication with the treatment liquid inside the chamber. In this way z. B. the rotation of an inner container in which the elements are present, moved within the chamber, z. B. rotated, or the inner container, which can be a basket, can be moved up and down, etc.

The magnetic recording can, for. B. be designed as the end of a tube, which protrudes in the center or elsewhere in the interior of the chamber.

In some embodiments, the elements can be subjected to a pre-treatment.

A pretreatment can e.g. B. immersing polymer elements in a pretreatment bath of one or more solvents for a certain time (up to 72 hours) at a certain temperature, which is preferably below the lower threshold temperature. Pre-treatment with a mist or steam with one or more solvents at a certain temperature and for a period of up to 48 hours can also be a suitable pre-treatment. The application of solvent mist can be carried out within a pre-treatment chamber, e.g. B. by means of ultrasonic generators (and heat) can be achieved. The effect of pre-treatment with steam can be achieved by increased temperatures and/or by negative pressure or vacuum within the pre-treatment chamber. If the polymer elements are pretreated accordingly, it is advisable to carry out the actual smoothing treatment within the shortest possible period of time.

In some embodiments, the elements may be post-treated.

• - Tauchen der Polymerelemente in Wasser bzw. einer Mischung aus Wasser und anderen Lösemitteln und/oder Salzen und/oder Säuren und/oder Basen für bis zu 96 Stunden bei Temperaturen bis zu 150°C. Das Behandlungsmittel und die Polymerelemente können dabei umgewälzt und/oder mit Ultraschall und/oder mit Vibration behandelt werden.
• - Behandlung der Polymerelemente mit warmer Luft oder warmen Gas. Eine solche Behandlung kann z. B. in einem Trockenschrank durchgeführt werden. Bevorzugt hat eine solche Heizkammer bzw. ein solcher Trockenschrank Vorrichtungen, womit das von den Polymerelementen abgeschiedene Lösemittel aufgefangen und bevorzugt wieder recycelt werden kann. Die Behandlung mit Wärme kann bei Temperaturen von bis zu maximal 10°C unter der Schmelztemperatur des jeweiligen Polymers durchgeführt werden. Die Polymerelemente werden dabei entweder aufgehängt oder aufgestellt, durch entsprechende Vorkehrungen wie Behältergefäße gegeneinander separiert oder in einer besonders bevorzugten Variante zusammen als Schüttgut behandelt. Dabei ist es besonders vorteilhaft, wenn sich die Polymerelemente während der Nachbehandlung bewegen und somit auch bevorzugt auch untereinander eine Relativbewegung erzielen.
• - Behandlung mit Unterdruck bzw. Vakuum. Eine solche Behandlung bewirkt, dass sich Restlösemittel aus dem Polymerelement löst. Durch bevorzugt kontinuierliches Absaugen aus einer entsprechenden Nachbehandlungskammer wird der aus der Polymerelementoberfläche austretende Dampf abgesaugt und dafür gesorgt, dass weiterer Lösemitteldampf aus den Polymerelementen in maximaler Weise austreten kann. Eine solche Behandlung wird bevorzugt mit gleichzeitiger Behandlung mit Wärme durchgeführt z. B. durch Strahlungswärme.

The post-treatment of the polymer elements, preferably for removing residual amounts of the solvent(s) from the surface of the polymer element or from the polymer element itself, is preferably carried out as follows:

• - Immersion of the polymer elements in water or a mixture of water and other solvents and/or salts and/or acids and/or bases for up to 96 hours at temperatures up to 150°C. The treatment agent and the polymer elements can be circulated and/or treated with ultrasound and/or with vibration.
• - Treatment of the polymer elements with warm air or warm gas. Such treatment can e.g. B. be carried out in a drying cabinet. Such a heating chamber or such a drying cabinet preferably has devices with which the solvent separated from the polymer elements can be collected and preferably recycled again. The heat treatment can be carried out at temperatures up to a maximum of 10°C below the melting point of the respective polymer. The polymer elements are either suspended or set up, separated from one another by appropriate precautions such as container vessels or, in a particularly preferred variant, treated together as bulk material. It is particularly advantageous if the polymer elements move during the after-treatment and thus preferably also achieve a relative movement among one another.
• - Treatment with negative pressure or vacuum. Such treatment causes residual solvent to dissolve from the polymer element. The vapor emerging from the surface of the polymer element is sucked off by preferably continuous suction from a corresponding post-treatment chamber and it is ensured that further solvent vapor can escape from the polymer elements to the maximum extent. Such a treatment is preferably carried out with simultaneous treatment with heat, e.g. B. by radiant heat.

The post-treatment options described can also be combined. In addition, it is advantageously possible to carry out a coating and/or functionalization step in a manner as described herein before, during or between the post-treatments.

Before, during or between the after-treatments, the elements can be subjected to mechanical surface treatments. In this case, blasting and/or vibratory grinding can be used particularly advantageously. Such a treatment by means of blasting and/or vibratory grinding can bring about microstructuring on the at least not yet completely cured surface of the polymer elements, which microstructures are permanently visible on the surface after preferably at least one further post-treatment. Such microstructures thus advantageously cause z. B. grained or matt surfaces. At the same time and/or alternatively, the surface roughness can advantageously be further reduced by at least one mechanical post-treatment before, during or between the post-treatments.

Some embodiments provide for the treatment liquid to be preheated to the smoothing temperature or above in the reservoir, for the elements to be arranged in the chamber and/or for the pressure in the reservoir to be increased, e.g. B. by means of compressed air or using nitrogen. In this way, hot treatment agent can be displaced into the chamber.

In some embodiments, it is provided that water, e.g. B. a smaller amount of water, into the chamber and heated to the upper treatment temperature or near the upper treatment temperature or let warm passively. The water will evaporate from approx. 100°C and thus wet and infiltrate the polymer elements with water vapor. In this way, the water can serve as a protective medium at depth during smoothing. In some embodiments, at least one temperature control device, in particular a so-called open temperature control device, is used and can be part of the device. The temperature control device can have a heat transfer medium which differs from the treatment liquid, e.g. B. a liquid heat transfer medium for storing thermal energy, z. B. a heat transfer oil. The temperature control device can be provided, the chamber, the reservoir or others Sections of the device to temper, especially to heat.

Such temperature control devices, referred to herein as open temperature control devices, can represent inexpensive solutions. The liquid heat transfer medium is heated in a storage tank for the heat transfer medium and conveyed to the chamber and/or to the storage container by means of a pump or in some other way. The advantage of this heating method compared to the system listed above is the possibility of pre-heating any large amount of heat transfer medium. This means lower connected loads, i. i.e. R. less than 10 kW, possible for the device with simultaneously high to very high heating rates during the smoothing step, which are necessary for the best possible smoothing.

In some embodiments, two or more compartments are provided for receiving elements. In this way, treatment liquid, which is required both in the first chamber and in the second chamber, can be pumped back and forth between the two chambers. While the treatment liquid in the first of these chambers is used in a smoothing step, the second of these chambers can be equipped with elements. Once the smoothing step has ended in relation to the first chamber, the treatment liquid can be pumped out of it and into the second chamber. The smoothing can begin in the second chamber, while the elements of the first chamber can be removed from it and the first chamber loaded with new elements. By providing several chambers, the performance of such a system can advantageously be multiplied.

In some embodiments, the polymer elements have no support section, in particular an integral or cohesively present or manufactured support section or no support element, in particular none that have to be removed from the polymer elements before they are used or are usually removed.

In some embodiments, the polymer elements include, or are or are made from, one or more polymers that have a melting point below 300°C, preferably below 250°C, most preferably below 200°C.

In some embodiments, the polymer elements are or are made from or with PA11, PA12 or TPU, preferably TPU-01.

In some implementation steps, the polymer elements are or will be manufactured by means of a powder bed, powder jet, material extrusion or treatment as a photopolymer

Some or all embodiments according to the invention can have one, several or all of the advantages mentioned above and/or below.

Elements obtained by additive manufacturing processes show great promise and are being produced in increasing quantities, but require a high quality finish. The present invention advantageously provides a method for smoothing, refining or refining the surface of an element that is obtained by an additive manufacturing method, which does not or essentially does not damage the surface, retains the complexity of the structure and shape of the element , can be performed in a short time and the use of mechanical steps, such as B. milling, grinding or polishing to avoid. This saves time and money.

Another advantage of the present invention can be that the elements obtained by additive manufacturing processes can be treated in bulk. By means of the present invention it can be advantageously avoided that the surfaces of the elements become sticky as a result of the treatment and/or that several elements stick to one another.

Furthermore, another advantage of the present invention may be that it provides a method for treating bulk materials using environmentally friendly materials and avoids the use of larger amounts of environmentally harmful organic solvents. This contributes significantly to environmental protection.

By means of the present invention it may further advantageously be possible to provide a method that can be used both for delicate parts and for bulky parts.

Another advantage of the present invention may be that reactivity can be finely and easily tailored. This also enables sensitive parts to be treated with a solvent, since the duration of the treatment can be precisely determined using the method according to the invention.

By means of the method according to the invention, both individual polymer elements and bulk material, i.e. several polymer elements simultaneously in the same process, can advantageously be treated by means of one method, the method for smoothing and optionally also for Functionalization of manufactured elements can be used, which were made from different types of polymers and in particular from polymers and copolymers based on polyamide and based on TPU.

A further advantage of the present invention can consist in the fact that it is possible to provide elements obtained by an additive manufacturing process with a smooth, matt and/or structured surface by treating the elements with the process according to the invention, the process making it possible To smooth surfaces of elements with very filigree parts, with high complexity, with channels, holes and fine structures in a short time and at comfortable temperatures.

In addition, it is advantageously possible by means of the present invention to treat the surface(s) of these elements in order to provide them with desirable functions, to color them or to functionalize them.

Advantageously, by means of the present invention, by using a liquid mixture of water and alcohol in predetermined proportions at a predetermined temperature and for a predetermined period of time, an efficient smoothing of the surface of elements and the simultaneous treatment of several elements as well as bulk material can be made possible, since the elements float in the treatment liquid and do not stick to each other. Start and stop of the smoothing reaction can be advantageously controlled by controlling the temperature regime and the treatment time. Thus, it is possible to advantageously precisely control the entire process so that surface softening, surface deterioration, rounding and softening of contour lines, etc. can be avoided.

With glycols such as propylene glycol or simple alcohols such as ethanol or isopropanol or also aqueous or non-aqueous mixtures thereof for smoothing by dipping or by smoothing bulk goods, other properties can advantageously be achieved in addition to high smoothing or low surface roughness. For example, with MJF or HSS elements, the surface can be colored from white to black or shades of gray in between. Due to the additive manufacturing process, such elements are black on the inside and usually have a gray surface, because white residual powder of the actually white powder sticks to the surface of the element, at least in small quantities. The described coloring from white to black can be achieved both by the smoothing process itself, for example by an appropriate selection of the treatment agent and/or appropriate treatment times and/or temperatures, and also by appropriate pre- and/or post-treatment. For example, the polarity of the granular media can result in greater mixing at the surface of the polymer elements, making them more black. This is preferably the case with granular media with non-polar properties. Granular media with strongly polar properties can strengthen the effect of gray or white coloring. The type of post-treatment in relation to the media used (air/gas/vacuum/liquid) and the temperatures used can also affect the color design of such surfaces. It has been found that post-treatment temperatures of 20°C to 80°C can produce a preferably lighter coloring on the surface of the elements over the long term than post-treatment temperatures of over 80°C. Without being bound to a theory, it is assumed that at lower post-treatment temperatures of up to 80°C, the residual treatment agent remaining in the surface or at least parts of it slowly or relatively slowly escape and thus no further displacement or mixing of polymer and carbon is possible Black is taken care of. At temperatures above 80°C, the escape of at least part of the residual treatment agent in the surface of the elements is increasingly increased and there can be a further or renewed displacement of carbon black on the polymer surface. In other words, it is assumed that at a post-treatment temperature above 80°C, at least parts of the carbon black, which is preferably at least partially pressed inwards on the immediate element surface by the smoothing step, with the residual treatment agent or at least parts of it escaping more violently compared to lower temperatures, are pressed further outwards again or are swept along, thus ensuring increased mixing of carbon black and polymer on the outer layer.

Another advantage of the present treatment can be the possibility to perform mechanical surface treatments before, during or between post-treatments. These can bring about microstructuring on the hardened surface of the polymer elements, which, after preferably at least one further post-treatment, are permanently visible on the surface. Such microstructures thus advantageously cause z. B. grained or matt surfaces. At the same time and/or alternatively, the surface roughness can advantageously be reduced by at least one mechanical post-treatment before, during or between follow-up treatments can be further reduced.

Furthermore, another advantage of the present invention may be that by applying the method of the invention it is possible to have elements containing carbon black change the color of the surface, allowing elements to be removed during the process or at a later date process step to color in many shades.

All the advantages that can be achieved with the method according to the invention can also be achieved undiminished in certain embodiments according to the invention with the device according to the invention and vice versa.

All in relation to a device according to 1 The embodiments described can be combined with an additional coloring and/or functionalization step by introducing suitable substances into the process chamber either before and/or during the smoothing step b) (see 4 ) and/or thereafter, for example in a time window after smoothing as previously described.

• 1 zeigt eine erfindungsgemäße Vorrichtung zur Durchführung des Verfahrens der vorliegenden Erfindung;
• 2 zeigt die Prozesskammer der Vorrichtung zur Durchführung des Verfahrens in einer zweiten Ausführungsform;
• 3 zeigt die Prozesskammer der Vorrichtung zur Durchführung des Verfahrens in einer dritten Ausführungsform mit einer zweiten Prozesskammer; und
• 4 zeigt schematisch vereinfacht den Ablauf eines erfindungsgemäßen Verfahrens in einer Ausführungsform.

The present invention is described below purely by way of example with reference to the attached figures. In them, the same reference symbols designate the same or similar components. The following applies:

• 1 shows an apparatus according to the invention for carrying out the method of the present invention;
• 2 shows the process chamber of the device for carrying out the method in a second embodiment;
• 3 shows the process chamber of the device for carrying out the method in a third embodiment with a second process chamber; and
• 4 shows a schematically simplified sequence of a method according to the invention in one embodiment.

1 shows an inventive device 100 for carrying out the method of the present invention.

This exemplary embodiment explains the device according to the invention in one embodiment by way of example, without restricting the scope.

The polymer elements can be used, for example, in a device as claimed in the present application and as in 1 shown to be treated. The device has a chamber or process chamber 1 with an optional cover 2 which comprises at least one inner container 3 for accommodating the polymer elements 4 and the treatment liquid 5 .

Temperature control means 26 are also provided, with the device preferably also comprising at least one of the following devices: a circulating device 7, a heating device 8 and/or at least one coolant tank 10, 20. In this case, the coolant tank 10, 20 includes a cooling fluid or coolant 22 This device is described and explained in more detail below and in the example.

The process chamber 1 is optionally designed as a pressure vessel and can have a cover 2 which is provided and/or suitable for closing the process chamber 1 in a pressure-tight manner.

The polymer elements 4 can be introduced into the process chamber 1 by means of the inner container 3 either as bulk material or in special chambers and/or holding devices (not shown) on and inside the inner container 3 .

The treatment liquid 5 can be introduced into the process chamber 1 in various ways.

The circulating device 7, preferably an impeller, is able to stir the treatment liquid 5 continuously.

Chambers and/or fixtures can be useful if the polymer elements 4 tend to stick together during smoothing, as can the provision of granular media within the process chamber 1.

This depends, among other things, on the geometry of the polymer elements and the polymer used, as well as on the smoothing intensity to be applied.

The circulation device 7 prevents the polymer elements 4 from sticking to one another or to the walls of the process chamber 1 by constantly stirring.

As described above, the treatment liquid 5 can be introduced in various ways.

In a first of these variants, the polymer elements 4 are introduced into the process chamber 1 and the cover 2 is closed in a pressure-tight manner.

The treatment liquid 5 is then introduced from the storage container 25 into the process chamber 1 by means of a pump 18 and/or pressurization by means of process gas from a tank 12 according to a predetermined level. In some embodiments, it can already have been brought to a predetermined temperature in the reservoir 25 for treatment liquid 5 by means of a heating device 27 .

The process chamber 1 can already be filled in advance with process gas from the tank 12 at a certain pressure in order to generate a back pressure during the filling phase of the treatment liquid 5 and/or to greatly prevent the treatment liquid 5 from suddenly evaporating. A pressure relief valve 13 may be provided in fluid communication with the tank 12 of process gas.

The conditions should be such that the treatment liquid 5 is in liquid form.

In a specific embodiment, a vacuum pump 24 provides for the displacement of almost all oxygen into the process chamber 1 before any gases or liquids are introduced into the process chamber 1.

An ideal (filling) level for the treatment liquid 5 depends on various factors, which will be described in more detail below.

It is optionally provided not to fill the entire process chamber 1 with treatment liquid 5, so that vapor 6, regardless of the source or liquid, in particular the treatment liquid 5, can fill the remaining space in the upper part of the process chamber 1.

In some embodiments it is provided that the polymer elements 4 are initially kept in the vapor 6 in the upper part of the process chamber 1 for a predetermined period of time before they are immersed in the treatment liquid 5 .

If necessary, the treatment liquid 5 can be heated to a temperature of approximately the lower threshold temperature of the polymer elements 4, the lower threshold temperature not only depending on the concentration and composition of the treatment liquid 5, but also on the polymer used in the elements 4 and also on the manufacturing process can depend.

When there is a sufficient quantity of treatment liquid 5 in the process chamber 1, the valve 16 can be closed. Configurations in which the treatment liquid 5 is not supplied from the outside, e.g. B. controlled via a valve, is introduced into the process chamber 1 are also disclosed herein.

Process gas 6 is then preferably introduced into the process chamber 1 .

The circulating device 7 can be switched on beforehand, at the same time or afterwards in order to distribute or circulate the treatment liquid 5 and the polymer elements 4 .

The treatment liquid 5 and the polymer elements 4 are brought to the required smoothing temperature by means of a heating device 8 .

This preferably takes place with a comparatively high to very high heating rate.

In order to regulate the temperature of the treatment liquid 5 as precisely as possible, preferably within the process chamber 1, a control or regulating device 14 is optionally provided.

The control or regulating device 14 can also be programmed to have or cause the method according to the invention to be carried out in each embodiment disclosed herein, for example by control commands to the components and/or actuators required for this purpose, in particular as disclosed herein.

The temperature is preferably continuously monitored by means of temperature sensors 26 . Means can be provided in order to heat up to the predetermined smoothing temperature as precisely as possible using a predetermined heating ramp.

A very rapid heating rate is desirable, as is maintaining the temperature within a predetermined temperature range.

Means (not shown) for a non-linear temperature increase, temperature ramps and/or a certain inert temperature increase or decrease by a few degrees (Celsius) after the smoothing temperature has been reached can be provided to further improve the method.

After a predetermined smoothing time, i.e. the duration of smoothing step b), the temperature to which the polymer elements 4 are exposed is optionally actively lowered to the range of the lower threshold temperature or lower at a predetermined cooling rate, which is advantageously high to very high.

This is preferably done via a cooling line 9 within the process chamber 1, which can be supplied with a coolant 22, preferably water, by a pump 11.

In addition or as an alternative, other cooling means can also be used, such as applying liquid nitrogen or removing process steam.

After the lower threshold temperature has been reached, the treatment liquid 5 can be pumped back into the storage tank 25, if present.

Optionally, the polymer elements 4 can be further treated by means of a rinsing liquid or a downstream coloring and/or functionalizing liquid 23, which is fed from another container 21 by means of a pump 19 via a valve 17 into the process chamber 1. This functionalization liquid 23 can then, ie after the downstream treatment, be pumped back into the container 21 and reused in some embodiments.

The functionalization liquid 23 can be simple water at room temperature in order to lower the residual temperature of the polymer elements 4 and the process chamber 1 to about room temperature as quickly as possible in order to be able to remove the treated polymer elements 4 after opening the lid 2 .

The process can be repeated.

In the 1 gas valves 15 are also shown, with which the gas supply into the process chamber 1 can be metered or regulated during and for the treatment.

In order to save energy, it may be advantageous to heat the polymer elements 4 and the treatment liquid 5 separately and to recover the treatment liquid 5 on cooling below the lower threshold temperature.

This can be done using a configuration where the treatment liquid 5 is heated in a separate container (not shown) to a temperature around the upper threshold temperature or above.

The heated treatment liquid 5 can then be pumped into the process chamber 1 comprising the polymer elements 4 and/or comprising the polymer elements 4 and water or an aqueous solution for pretreatment. If treatment liquid 5 is fed into the process chamber 1 at a temperature in the range of the upper threshold temperature or higher, the temperature is slightly lowered due to the lower temperature of the polymer elements 4 and the thermal mass of the process chamber 1 . This enables rapid heating of the polymer elements 4 to the smoothing temperature and a rapid smoothing effect.

Example

Polymer elements were smoothed using the method of the present invention. The polymer elements were first treated at a temperature below a lower threshold temperature where time is not critical.

Only when this temperature is exceeded does a noticeable reaction take place. Below the lower threshold temperature, smoothing or surface changes do not occur in a few minutes or over a period of several hours. This means that the polymer elements can remain in the treatment liquid or another pre-treatment liquid such as water or an aqueous solution for any length of time. This enables a high degree of flexibility for the process. The lower threshold temperature depends on the treatment liquid and on the type of polymer elements to be treated. Thus, the lower threshold temperature may vary, e.g. B. depending on the polymer elements made with different manufacturing processes such as SLS and MJF. It can generally be assumed that this lower threshold temperature is at least 5°C and up to 50°C or more below the upper threshold temperature.

The "lower threshold temperature" does not necessarily have to be an exact temperature value, but can be a temperature range comparable to the melting range of a polymer.

Since smoothing begins slowly beyond the low threshold temperature, this is not critical as long as any pretreatment that should not start smoothing is performed well below the low threshold temperature. When treating polyamide elements and the treating liquid is a water-alcohol mixture with a water to alcohol ratio of 60:40 to 40:60, the lower threshold temperature is usually higher than 100°C and lower than 145°C.

Until the lower threshold temperature is reached, the heating rate does not play a significant or direct role in polymer element quality.

The actual smoothing process starts slowly once the lower threshold temperature is reached. This temperature can be maintained for some time, or alternatively or additionally, one or more temperature soak cycles can be established to heat the treatment liquid and optionally the polymer elements to around the lower threshold temperature. These soak cycles, or alternatively a delayed heating rate, can be beneficial to saturate the polymer elements with water using an aqueous medium such as water or a water-alcohol mixture. In other words, the polymer elements can be pretreated with water or an aqueous liquid or the treatment liquid before the smoothing step as such begins, which means that the polymer elements can be brought into contact with an aqueous medium at a lower temperature and heated slowly or for a be maintained at a temperature below the lower threshold temperature for any useful length of time. Smoothing starts when the treatment liquid is heated to a temperature above the lower threshold temperature. Various approaches to heating are possible.

In one approach, the treatment liquid with the polymer elements therein is heated very rapidly from the lower threshold temperature to, preferably at most or preferably at least, the upper threshold temperature.

The heating rate should preferably be high to very high. The temperature should be controlled as closely as possible. In addition to the well-known heating characteristics, it is preferred to control and detect possible energy fluctuations in the process chamber due to evaporation and to provide means to counteract these in a process-improving manner, for example by providing circulating, driving or propellant means. Once the upper threshold temperature or a temperature close to it has been reached, e.g. B. 1 ° C to 5 ° C below the upper threshold temperature, this temperature for a short period, z. e.g. a few seconds up to a few minutes. The temperature regime can be adjusted to achieve optimal results, for example using a predetermined heating rate until a desired temperature of 1°C to 5°C below the upper threshold temperature is reached, maintaining that temperature for a few seconds or up to 2 minutes is held and then cools it down with or without a predetermined cooling rate. The heating rate and hold time can be adjusted for optimal results and the optional cooling rate can also be adjusted accordingly.

For example, means can be provided to enable a shorter or longer holding time and adjustment of temperature ranges by rapid or slow temperature increase and/or decrease. In general, it is preferable to have a rapid temperature rise to the predetermined smoothing temperature and a rapid temperature fall to the lower threshold temperature in order to complete smoothing as quickly as possible. Periods of increase and decrease in the range of less than 5 minutes, preferably less than 2 minutes are preferred.

The smoothing step is followed by a cooling step in which the temperature inside the process chamber is lowered.

This can be done using any means known in the prior art and can be done as quickly and/or in a controlled manner as possible, at least until the lower threshold temperature is reached, preferably by means of active cooling media. Examples of active coolants are pipe cooling lines or cold exchangers arranged within the process chamber. A further possibility of lowering the temperature quickly can be achieved by selectively discharging process gas within the process chamber, preferably into a third chamber. By selectively discharging process vapor into a deliberately arranged gas space above the actual treatment liquid within the process chamber, further vapor is generated from the liquid, which leads to a cooling of the treatment liquid.

Typical heating rates from the lower threshold temperature to the upper threshold temperature are 1°C/min to 60°C/min, such as 5°C/min to 20°C/min.

Cooling rates can be in the same range, but can also be slower or faster.

In an alternative embodiment, the treatment liquid, for example an ethanol-water mixture, is not heated from around room temperature to the lower threshold temperature every time, but is pumped into a second chamber after the smoothing step, where it is kept at around the same temperature and used for the next Smoothing charge can be used again.

In another approach, the ethanol-water mixture is heated separately to a temperature higher than the lower threshold temperature, for example to the upper threshold temperature or more, in a second chamber. The temperature of the treatment liquid should be at the This procedure can at most be such that when the treatment liquid comes into contact with the polymer elements to be smoothed, the temperature during pumping from the second chamber into the process chamber and/or through contact with the polymer elements drops down to approximately the upper threshold temperature. In the process chamber, this temperature can either be maintained as a function of the initial temperature and the thermal mass of the process chamber wall and the polymer elements, or it can be adjusted to the optimal upper threshold temperature by active heating or cooling. After a predetermined treatment time with the preferred smoothing process parameters or within the preferred smoothing process parameter ranges, the temperature of the treatment liquid is brought back below the lower threshold temperature by the cooling options already described.

The treatment liquid can then be pumped back into a second chamber.

In another approach, the treatment liquid 5 from the reservoir 25 is not cooled to or below the lower threshold temperature, but is preferably maintained in a second chamber at a temperature suitable for smoothing, such as slightly above or at the upper threshold temperature.

If the treatment liquid 5 is fed into the process chamber 1 at a temperature of about the upper threshold temperature or slightly below or above, its temperature will be slightly lowered by the lower temperature and the thermal mass of the process chamber 1 and the polymer elements 4 arranged inside the process chamber 1. This approach enables the polymer elements 4 to be heated rapidly in a shorter time than by heating the polymer elements 4 directly in the treatment liquid 5. Therefore, this approach is suitable in cases where rapid heating and smoothing is required. The heating of the treatment liquid 5 and the polymer elements 4 together normally requires more time since the heating device 8 can only bring in a certain heating capacity. In an alternative method, the smoothing process can be stopped more slowly so that the surface of the polymer elements is in a transitional phase in which the surface is still soft. This makes sense if a functionalization step is carried out after the smoothing step or if a second smoothing step follows. This improves the surface finish while maintaining the exact geometric contours.

Another way to stop the smoothing process is to introduce liquid nitrogen into the chamber. This can be advantageous if the inlet pressure is kept as low as possible by introducing compressed air and/or process gas.

In an additional step of an embodiment of the process of the present invention, or as part of one or more of the steps, colorants and/or fillers may be added to the polymeric element surface during the process.

For this purpose, the alcohol-water mixture is mixed directly with the dye and/or the fillers. Dyeing with disperse, metal complex or acid dyes or sulfur dyes can also be done either directly after smoothing or in the process chamber with an additional dye tank 23 . Coloring directly after the smoothing process can have advantages when coloring, since the surface still has a certain softness due to the ethanol content, which means that certain colorants or fillers can penetrate the surface better and in a shorter time.

In addition to alcohols, substances that increase the polarity of water can lighten MJF and HSS components on the surface. Without being bound by theory, it is believed that increasing polarity of the liquid increasingly displaces the relatively non-polar carbon black inwards within the components mentioned, preferably at a temperature above the crystallinity range of the polymer. Suitable materials for whitening are e.g. B. tap water or mineral water. However, in some embodiments, the temperature in the range of the crystallinity temperature should be increased significantly. If salts are added to the water, this can happen at temperatures of around 140°C. It has been found that, in general, treating polymer elements with a salt solution, for example an aqueous solution of a salt such as NaCl and/or Na ₂ CO ₃ , for example at a concentration of from about 1% to about 20% by weight -% the surface of the polymer elements can become light gray to whitish. This is achieved for polymer elements obtained by additive manufacturing when they contain carbon black, independently of a treatment with a water-alcohol mixture for smoothing as described above. For the whitening effect, a saline solution can be used along with the additives mentioned above such as benzyl alcohol, glycerin, glycols or plasticizers used in small amounts.

2 shows the process chamber 1 of the device 100 for carrying out the method 100 in a second embodiment.

For better clarity are in 3 only the process chamber 1 of the device 100 (with sections of its supply and return lines) is shown. Reference is made to the reference numerals and explanations 1 referred.

If an additional coloring and/or functionalization step, either during the smoothing step b) (see 4 ) and/or thereafter, this is done by introducing suitable substances into the process chamber 1.

The example of 2 shows the process chamber 1 with a container 21a accommodated therein for dyes or functionalizing agents, from which the substance is introduced into the process chamber 1 at a suitable time, in particular automatically, by means of suitable means provided for this purpose (e.g. pumps, valves or the like). can be.

The container 21a can, for example, be filled with dyes (liquid or as a powder), pigments, functionalizing agents (eg as a powder or with fibers) or with additives.

3 shows the process chamber 1 of the device 100 for carrying out the method in a third embodiment with a second process chamber 1a.

For better clarity are in 3 only the process chambers 1, 1a of the device 100 are shown. Reference is made to the explanations of the two preceding figures.

Using the exemplary arrangement of 3 the performance of the device 100 can advantageously be doubled by two process chambers 1, 1a. In some embodiments, for example, the reservoir 25 (see 1 ) be designed as a second main chamber.

In the example of 3 the two process chambers 1, 1a are in fluid connection and existing treatment liquid 5 can be pumped back and forth between the process chambers 1, 1a for the treatment process.

Thus, treatment liquid 5, which is required both in the first process chamber 1 and in the second process chamber 1a, can be pumped back and forth between the two chambers by means of the pumps 30, 30a.

For example, while the treatment liquid 5 in the first process chamber 1 is used in a smoothing step for the polymer elements 4, the second process chamber 1a can be equipped with further polymer elements 4a. Once the smoothing step has ended in relation to the first process chamber 1, the treatment liquid can be pumped out of it and into the second process chamber 1a by means of the pump 30. Then the smoothing of the polymer elements 4a in the second process chamber 1a can begin, while the polymer elements 4 of the first process chamber 1 are removed from the latter and the first process chamber 1 is then fitted with new polymer elements 4 . After completion of the smoothing step of the polymer elements 4a, the treatment liquid 5 can be conveyed back into the first process chamber 1 by means of the pump 30a, so that the next smoothing step can be carried out there, etc.

This arrangement is purely exemplary and not to be construed as limiting. In certain specific embodiments, only one line can optionally be provided between the process chambers 1, 1a with a pump that can deliver in both directions.

The performance of such a device 100 can thus be multiplied by providing a plurality of process chambers.

4 shows a schematically simplified sequence of a method according to the invention in one embodiment.

It is referred to the reference numerals of 1 until 3 referenced.

Step S1 represents providing a treatment liquid in a chamber 1 of a device 100.

Step S2 designates providing the polymer elements to be treated.

An optional heating step for heating the treatment liquid to a temperature below an upper threshold temperature is represented by step a). The upper threshold temperature is in this case, for example, in a range from approximately 1° C. to approximately 80° C. below the melting temperature of the polymer from which the polymer elements are formed.

Step b) represents a smoothing step. Here, the polymer elements are or come into contact with the treatment liquid at a temperature above a lower threshold temperature and below the upper threshold temperature for a predetermined period of time. Conditions prevail in which the treatment liquid is in liquid form.

Step c) represents an optional cooling step for cooling the polymer elements.

Reference List

1, 1a

process chamber

2, 2a

Lid

3, 3a

inner container

4, 4a

polymer elements

5

treatment liquid

6, 6a

process steam; process gas

7, 7a

circulation device

8th

heater

9

cooling line; cooling surface; cooling device

10

coolant tank

11

pump

12

Process gas tank

13

pressure relief valve

14

Control or regulating device

15

gas valve

16

Valve for liquid treatment

17

Valve for functionalization liquid or component cooling liquid

18

pump

19

pump

20

coolant tank

21, 21a

containers for functionalization liquid or component cooling liquid; paint tank

22

coolant

23

Functionalization of liquid or component coolants

24

vacuum pump

25

Storage tank for treatment liquid

26

temperature sensors and pressure sensors

27

heater in storage

30, 30a

pump

100

contraption

Claims (28)

A method of treating polymeric elements (4) obtained by an additive manufacturing process, comprising - Providing a treatment liquid in a chamber (1) of a device (100); - Providing the polymer elements (4) to be treated; further comprising the steps a) optionally: a heating step for heating the treatment liquid to a temperature below an upper threshold temperature, the upper threshold temperature being in a range from 1°C to 150°C below the melting temperature of the polymer from which the polymer elements (4) are formed; b) a smoothing step, wherein the polymer elements are in contact with the treatment liquid at a temperature above a lower threshold temperature and below the upper threshold temperature for a predetermined period of time, under conditions where the treatment liquid is in liquid form, and c) optionally: a cooling step for cooling the polymer elements (4). procedure after claim 1 wherein the treatment liquid comprises water and at least one, preferably monohydric, preferably aliphatic, alcohol, the weight ratio of the water to this alcohol being in a range from 99:1 to 1:99. Method according to one of the preceding claims, wherein granular media are present in the treatment liquid or are or are brought into contact with the treatment liquid, preferably as a separating agent. procedure after claim 3 , wherein the granular media consist of ceramic, glass, metal, plastic(s), natural materials such as chippings, corundum or (walnut) nut shells, or are mixtures/compounds thereof or have these materials or mixtures. Procedure according to one of claims 3 until 4 , wherein at least temporarily mixing of the treatment liquid with the polymer elements and the granular media is ensured during the smoothing step b). procedure after claim 5 , wherein the mixing takes place in the form of flow, preferably by a ring and/or upflow and/or vibration, sound or ultrasound and/or possibly other forms such as pressure changes. Method according to any one of the preceding claims, wherein the polymer elements (4) before the smoothing step b) in an upper portion of the chamber (1) in which the smoothing step b) takes place or will take place, which is filled with gas, e.g. B. at normal pressure, below or above, is held available in a vapor deposition step over a predetermined minimum period. procedure after a claim 7 wherein the gas pressure in an upper portion of the chamber (1) is regulated or adjusted during the vapor deposition step. Procedure according to one of Claims 7 until 8th , wherein the vapor deposition step corresponds to the heating step a) or overlaps in time with it. Procedure according to one of claims 2 until 9 , wherein the water in the treatment liquid is replaced or exchanged in whole or in part by glycerol, a glycol, in particular a polyethylene glycol. A method according to any one of the preceding claims, wherein the upper threshold temperature is in a range of 50°C to 325°C, preferably 70°C to 190°C. A method according to any one of the preceding claims, wherein the treatment liquid comprises water and ethanol in a weight ratio of 98:2, or 95:5, to 10:90 and/or wherein the treatment liquid is at a temperature in the range of 120°C to 180°C is applied under conditions where the treatment liquid is in liquid form. A method according to any one of the preceding claims, wherein the treatment liquid is or comprises propylene glycol, with or without the addition of water. Method according to one of the preceding claims, wherein the treatment liquid comprises at least one additional solvent and/or at least one plasticizer, the total amount of additional solvent and/or plasticizer being up to 20% by weight, preferably up to 10% by weight. Method according to any one of the preceding claims, wherein - either during the heating step a) the polymer elements (4) to be treated are present in the treatment liquid and are in contact with them during the heating, or - the heating step a) comprises that the treatment liquid is heated at least to the lower threshold temperature, up to the upper threshold temperature or more, and that the polymer elements (4) separately in an aqueous solution and/or aqueous vapor to a temperature below the upper threshold temperature are heated, and wherein in or for the smoothing step b) the treatment liquid and the polymer elements (4) are brought into contact with one another for smoothing. Method according to one of the preceding claims, wherein in at least one step at least one functionalizing agent is applied to the polymer elements (4) during or after the treatment with the treatment liquid. procedure after Claim 16 wherein at least one functionalizing agent is applied during or after step c), the method preferably further comprising a step d) for functionalizing the smoothed polymer elements (4) by applying at least one functionalizing agent. Method according to one of the preceding claims, wherein during at least one of steps a) to c) and / or during the functionalization step d) means for driving the treatment liquid and / or the functionalizing agent are used, wherein the driving means is preferably at least one impeller or an ultrasonic unit or a vibration unit. Procedure according to one of Claims 16 until 18 wherein the functionalizing agent comprises at least one agent selected from a colorant, a dye, a pigment, a fiber, a curing agent, a metal powder, a polymer powder, an inorganic pigment or powder, an electrostatic discharge agent, a filler, a base, an acid , a buffer solution, a finishing agent and/or a plasticizer. Procedure according to one of Claims 16 until 19 , wherein in the functionalization step d) a colorant or a dye solution is applied. Method according to any one of the preceding claims, wherein the polymer of the polymer elements (4) is selected from a polymer or copolymer based on polyamide, a thermoplastic elastomer such as thermoplastic polyurethane (TPU), thermoplastic polyamide (TPA), thermoplastic copolyester compound (TPC), or thermoplastic Styrene block copolymers (TPS) such as styrene/ethylene/butylene/styrene block copolymer (SEBS) or acrylic polymers such as acrylonitrile Butadiene-Styrene (ABS), Acrylic Ester-Styrene-Acrylonitrile (ASA) or one of PMMA, POM, PC, PEI, PSU or Polybutylene Terephthalate (PBT) or a copolymer or a mixture thereof. Device (100) for the treatment of polymer elements (4) obtained by an additive manufacturing process, comprising a chamber (1) with a lid (2), at least one container for receiving the polymer elements (4) and the treatment liquid (5) and Means for temperature control (26), the device preferably further comprising at least one of a circulating device (7), a heating device (8), an ultrasonic unit, a vibration unit and a coolant tank (10, 20) with a cooling fluid (22). Device (100) according to Claim 22 , prepared for carrying out the method according to one of Claims 1 until 21 . Device (100) according to one of Claims 22 until 23 wherein a container (21a) for additives is placed in the chamber (1). Device (100) according to Claim 24 , wherein the container (21a) for additives is filled with dyes, pigments, functionalizing agents and/or additives. Device (100) according to one of Claims 22 until 25 , wherein a reservoir (25) with warmer or colder treatment liquid than the treatment liquid in the chamber (1) is in fluid communication with the chamber (1). Device (100) according to Claim 26 wherein the fluid connection is operatively connected to a circulating pump and/or means for pressurization. Device (100) according to one of Claims 22 until 27 , A magnet bushing being provided for the movement of the inner container (3), in particular its rotation and/or up/down movement.

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