EP3849778A1

EP3849778A1 - 3d-printed elastic products reinforced by means of continuous fibres and having asymmetrical elastic properties

Info

Publication number: EP3849778A1
Application number: EP19762999.1A
Authority: EP
Inventors: Dirk Achten; Nicolas Degiorgio; Jonas KÜNZEL; Thomas BÜSGEN
Original assignee: Covestro Intellectual Property GmbH and Co KG
Current assignee: Stratasys Inc
Priority date: 2018-09-14
Filing date: 2019-09-10
Publication date: 2021-07-21
Also published as: EP3623137A1; US20210324177A1; WO2020053168A1; CN112654489A

Abstract

The present invention relates to a fibre-reinforced 3D-printed elastic product (1, 3, 4, 7, 10, 12), wherein the product comprises a weight proportion of ≥ 50% of a polymer having a mean molecular weight of ≥ 5000 g/mol, measured by means of GPC, and a weight proportion of ≥ 0.5% and ≤ 20% of one or more fibres having an aspect ratio of ≥ 100 and a length of ≥ 3 cm and ≤ 1000 cm, the product being produced at least in part by means of an FFF (Fused Filament Fabrication) method, and the product having a tensile modulus of ≥ 1.5 GPa in the region of the fibre reinforcement and in the direction of the fibre symmetry axis. The product also has a tensile modulus, measured according to DIN EN ISO 527-1, of ≤ 1.2 GPa in the region of the fibre reinforcement and perpendicular to the fibre symmetry axis, and has a yield strength of > 5%, measured according to DIN EN ISO 527-1, perpendicular to the fibre symmetry axis.

Description

Continuous fiber reinforced 3D printed elastic products with asymmetrical elastic properties

The present invention relates to a fiber-reinforced, 3D-printed elastic product, the product having a weight fraction of> 50% of a polymer with an average molecular weight of> 5,000 g / mol, measured by GPC, and a weight fraction of> 0.5% and <20 % of one or more fibers with an aspect ratio of> 100 and a length of> 3 cm and <1000 cm, the product being produced at least in part by means of an FFF (Fused Filament Fabrication) process and the product in the field of fiber reinforcement and in Has a tensile modulus of> 1.5 GPa in the direction of the fiber symmetry axis.

The properties of products result in a complex way from the manufacturing process and the materials used. As a rule, the properties of the finished workpiece can be specifically changed both as a function of the parameters in the manufacturing process and via the composition of the basic materials used, so that (if possible) end products with completely different properties can be obtained via the complex matrix of both influencing variables. This fundamental relationship generally arises for all manufacturing processes and can be broken down into the individual active components by gathering production experience. In the context of modern manufacturing processes, which are based on several stages or parallel process steps, these cause-effect relationships are more difficult to determine, since recourse to many years of production experience is not possible. This applies, for example, to the manufacture of products using 3D printing, a method of manufacture that is relatively new compared to other methods for the production of molded articles, with the fact that the properties of the molded articles produced also result in a complex manner from the interaction between the production process and the one used Material. The complexity of 3D printing can also increase if, in addition to the “simple” printing of a base material, more complex mixtures and / or different materials with different properties and interactions that are difficult to predict are used. This can result in product properties that cannot be extrapolated from the properties of the materials used.

3D printed products with fiber reinforcement and their manufacture are described in the prior art.

For example, US 9,688,028 B2 discloses a method for producing anisotropically filled 3D printed bodies. The method involves receiving a three-dimensional geometry and cut into layers. A first anisotropic fill tool path for controlling a three-dimensional printer for depositing a substantially anisotropic fill material is generated, which defines at least a part of an interior of a first layer. A second anisotropic fill tool path for controlling a three-dimensional printer is created to deposit the substantially anisotropic fill material that defines at least a portion of an interior of a second layer. A generated isotropic filler toolpath defines at least a portion of a perimeter and at least a portion of an interior of a third layer that lies between the first and second layers.

US 2016/0067928 A1 describes a method for producing anisotropically filled 3D printed bodies by means of the FDM method, comprising the deposition of at least one isotropic and at least one anisotropic material. The document describes that a three-dimensional geometry is received and cut into layers. A first anisotropic fill tool path for controlling a three-dimensional printer for depositing a substantially anisotropic fill material is created that defines at least a portion of an interior of a first layer. A second anisotropic fill tool path for controlling a three-dimensional printer to deposit the substantially anisotropic fill material defines at least a portion of an interior of a second layer. A generated isotropic filler toolpath defines at least a portion of a perimeter and at least a portion of an interior of a third layer that lies between the first and second layers.

Another patent document, US 2018/0072040 Al, describes the 3D printing of long fiber reinforced thermoplastics in an FDM process for the production of fiber reinforced components. The method includes receiving a first 3D toolpath that defines a curved fill material shell, receiving first 2D toolpaths that define flat carrier shells, receiving a second 3D toolpath that defines a curved shell made of long fiber composite material, the long fiber composite material being a filament comprises with a matrix; Embedding fibers with a catch more than twice the diameter of the filament, actuating a filler deposition head to trace the first 3D tool path in order not to deposit the filler-curved shell parallel to a printing substrate, actuating a substrate deposition head to track the first 2D Toolpaths to deposit substrate in a series of substantially flat shells and actuate a long fiber deposition head so as not to track the second 3D toolpath parallel to the print substrate to deposit the curved shell made of long fiber composite material, at least part of the filler material encloses curved bowl. CN 106 313 496 A also describes a process for processing continuous fibers together with thermoplastics in a special FDM process. The document discloses a 3D printing process for a continuous fiber reinforced thermoplastic resin matrix composite material and a printhead. According to the method, fiber bundles and melted thermoplastic resins can be rotationally mixed and then subjected to rotational extrusion, the extruded wires being spiral; and the printhead can load the fiber bundles and the thermoplastic resins in a melt cavity, and spiral toothed rings are located on the inside of the melt cavity and an extrusion head and rotate in opposite directions. The heated molten resins and fibers are stirred by the spiral toothed rings which, after mixing, rotate in two directions so that the fibers are compactly wound from a flat shape into a spiral column shape, the resins are evenly distributed in each fiber orientation and then becomes one Mix extruded from an extrusion orifice to a molding area, cooled and hardened to form a spatial unit. According to the process and the printhead, the flat large cable fibers can be used as reinforcements in a 3D printing process, the compactly wound fibers have a high degree of compaction, the fibers and the matrices are sufficiently impregnated, and the fibers and resins formed are evenly distributed; therefore, the method and the printhead are capable of improving the mechanical properties of an element and the quality of the molding.

WO 2015/120429 A1 describes a process for processing continuous fibers by extrusion of a thixotropic, post-crosslinkable liquid containing fillers in addition to the fibers. The document describes a filament structure that is extruded from a nozzle during 3D printing, which comprises an endless filament with filler particles dispersed therein. At least a portion of the filler particles in the continuous filament include high aspect ratio particles that have a predetermined orientation with respect to a capture axis of the continuous filament. The high aspect ratio particles can be at least partially aligned along the capture axis of the continuous filament. In some embodiments, the high aspect ratio particles can be strongly aligned along the capture axis. Also or alternatively, at least a portion of the high aspect ratio particles may have a helical orientation that includes a peripheral component and a capture component, the peripheral component being created by rotating a deposition nozzle and the capture component being transferred by translation of the deposition nozzle.

WO 2018/081554 A1, on the other hand, describes a method for producing continuous fiber-reinforced components for use as implant materials. The document describes procedures and Devices for printing a three-dimensional fiber structure. A layer of fibers is printed on a printing surface by pressing fibers through at least one extrusion die and onto the printing surface. The extrusion nozzle and / or printing surface are moved in the X, Y and / or Z direction during the printing of the fibers. The method can be used to manufacture medical bandages, hernia nets, vascular implants, knee menisci or rotator cuffs.

US 2018/0131124 A1 describes a process for the production of 3D printed seals including reinforcing fillers. The document discloses an electrical connector assembly for electrical submersible pumps (ESPs) having a liquid-impermeable, 3D-printed seal between the power cable and an inner housing component of the electrical connector assembly. Electrical insulation or a dielectric for a wire of the power cable can also be 3D-printed integrally with the fluid seal. The housing component, for example an internal electrical housing, can also be 3D-printed integrally with the printed seal. Similarly, in one implementation, the 3D printed seal, internal housing component and outer quiver housing can all be printed on the power cable as a unit. The 3D printed sealant and associated bucket components can be made from a variety of chemical resistant materials such as printed polyaryl ether ketones, printed fluorinated polymers and metal alloys. The 3D printed seal may also contain barrier materials or reinforcing fillers to improve strength and chemical resistance to borehole fluids and gases.

US 2016/0159007 A1 describes a method for producing conveyor belts for the paper industry, at least part of which is 3D printed. The document discloses a paper production belt with material zones which are deposited one after the other by means of a 3D printing process. The zones include at least one pocket zone configured to form three-dimensional structures in a paper web by applying a vacuum to pull the paper web against the pocket zone. In at least one exemplary embodiment, the zone also includes at least one vacuum interruption zone configured to limit an amount of paper fibers drawn through the pocket zone by the applied vacuum.

US 2016/012935 A1 discloses a starting material for additive manufacturing processes with a matrix material and fibers containing one or more barbs, which are present within the matrix material. Each barb-containing fiber has a central filament and one or more barb structures. The barb structures are designed to protrude outward from the central filament after extrusion. Process for the preparation of the Starting material and methods of using the starting material to make three-dimensional objects are also disclosed.

US 2018/001547 A1 relates to a method for producing an individualized immobilization element for the non-invasive immobilization and / or mobilization of at least one segment of a body part of a patient in a predetermined position relative to a reference and / or in a predetermined configuration. The method comprises the steps (i) providing a data set comprising a three-dimensional image of an outer contour of at least part of the body segment to be immobilized and / or mobilized and (ii) producing at least part of the immobilization element by rapidly producing a shape based on the data set using a polymeric material with a thermoplastic polymer, which has a melting point of <100 ° C, wherein the polymeric material contains a nucleating agent to support the crystallization of the thermoplastic polymer.

The prior art discloses the production of complex workpieces using 3D processes. The production of printed products with elastic behavior and highly asymmetrical mechanical properties, however, does not disclose the prior art.

It is therefore the object of the present invention to provide complex 3D-printed fiber-reinforced elastic products which have anisotropic and preferably very strongly anisotropic mechanical properties.

A 3D-printed product is therefore proposed according to claim 1. Advantageous further developments are specified in the subclaims. They can be combined in any way, unless the context clearly indicates the opposite.

According to the invention is a fiber-reinforced, 3D-printed elastic product, the product having a weight fraction of> 50% of a polymer with an average molecular weight (M _n ) of> 5,000 g / mol, measured by GPC, and a weight fraction of> 0.5% and <20% of one or more fibers with an aspect ratio of> 100 and a length of> 3 cm and <1000 cm, the product being produced at least in part by means of an FFF (Free Filament Fabrication) process and the product in the range of Fiber reinforcement and in the direction of the fiber symmetry axis has a tensile modulus measured according to DIN EN ISO 527-1 of> 1.5 GPa.

According to the invention, the axis of symmetry of a fiber is parallel to the longitudinal axis of the fiber, that is to say parallel to the fiber axis with the greatest spatial fiber extension. This is described in more detail below. The products according to the invention have several advantages over the printed products described in the prior art. Based on the combination of the chemical properties of the base material and based on the production using 3D printing and additional fiber reinforcement, complex mechanical properties of the product result. The printed products are fundamentally elastic, whereby they have an extraordinarily high strength and rigidity in the direction of the axis of symmetry of the fibers which are also printed. Perpendicular to these later directions of loading, the product has an extremely high elasticity, ie low rigidity and / or lower strength. In this direction there is also a high reversible deformability, which is of great importance for the repeated loading of the product without breaking or fatigue. Based on this combination, the product shows an extraordinarily high anisotropy in the mechanical properties, which enables the successful use of these products in completely new areas of application. The high anisotropy in the mechanical properties can be demonstrated, for example, by clearly different mechanical parameters such as module anisotropy, damping anisotropy, and anisotropy in yield stress. The term "anisotropy" indicates that these mechanical values for characterizing the product as a function of the measuring direction are not the same, but are significantly different. The prior art, however, discloses either elastic or resilient printed products with a more or less isotropic load-bearing capacity and / or material stiffening. This can be disadvantageous in many areas of application. Without being bound by theory, the high mechanical strengths in the direction of the fibers can result in particular from the use of elastic base polymers in the claimed molecular weight range and the special dimensions of the incorporated fibers.

The product according to the invention is a fiber-reinforced, 3D-printed elastic product. A 3D printed product was at least partially manufactured using a 3D printing process. All or only a portion of the product can be produced using 3D printing. At least one of the 3D-printed sections has fibers in addition to the printed elastic polymer within the printed polymer matrix. This means that this or these sections are fiber-reinforced in the sense that not only a 3D-printed polymer but also a 3D-printed polymer with at least one integrated fiber with the dimensions and properties according to the invention is present within these sections of the product. In the sense of the present invention, a product is elastic if it shows an elongation at break in the tensile test according to DIN 53504 of> 50%. The product can have, for example, a compression set after 10% compression (according to DIN ISO 815-1) of <50%, preferably <30%, particularly preferably <15%. The product is> 50% by weight polymer. The proportion of polymers in relation to the other product proportions can be decisive for the elastic properties of the product. By means of the method disclosed here, however, products are also obtainable which can be “highly filled”, that is to say that in addition to the polymer and the fibers, they can also have other fillers in significant proportions. These highly filled products are also encompassed by the invention. For the purposes of the invention, polymers are macromolecules which are composed of repeating, identical units. Examples of polymers or polymer mixtures which can be used are listed further below. The determination of the content is known to the person skilled in the art and can be carried out after dissolving the product, for example by means of gel permeation chromatography (GPC) in the case of non-crosslinked soluble polymers. In the case of partially insoluble polymers by thermogravimetry (TGA) after selective thermal decomposition in order to distinguish the polymers from, for example, inorganic, higher-decomposing fillers. Complementary to this, elemental analyzes can be carried out to quantify the organic components compared to inorganic components. The person skilled in the art is familiar with the test methods to be used to determine the proportions by weight. Polymer contents of> 55% have been preferred for many applications

> 60%, further preferably> 65%, and> 70% have been found to be advantageous for obtaining preferred elastic product properties.

The polymer has an average molecular weight (M _n ) of> 5,000 g / mol, measured by means of GPC. The average molecular weight means the number average molecular weight. The polymer used can have a mass distribution, the quotient of the total mass and the number of particles having to be greater than the value given above. The distribution and the mean value of the distribution can be determined by means of GPC on the finished product. For this purpose, the product is expediently dissolved and subjected to a GPC. As a function of the polymer used, the person skilled in the art knows the suitable GPC conditions, including the solvents that can be used for dissolution. The polymer can preferably also have an average molecular weight of 10,000 g / mol, further preferably of> 12,000 g / mol, and also preferably of> 15,000 g / mol and particularly preferably of> 20,000 g / mol. In the case of partially insoluble and partially crosslinked polymers (e.g. in the form of a polymerized organic filler or specks in a thermoplastic matrix), the molecular weight of the soluble and extrudable matrix is defined as decisive, since at least partially crosslinked fractions are assumed to have an “infinite” molecular weight can. These molecular weights can lead to sufficient elastic properties of the printed polymer. Very high average molecular weights

> 5,000,000 g / mol, on the other hand, are disadvantageous because they are difficult to extrude in the area of 3D printing. Low molecular weights can be disadvantageous because of these have insufficient elastic properties. The GPC examination can be carried out, for example, in DMF at 23 ° C. and / or 80 ° C. on a polystyrene / divinylbenzene column material against PMMA as a standard.

The product has a weight fraction of> 0.5% and <20% of one or more fibers. Fibers in the sense of the invention are linear structures which consist of a fibrous material and generally have a defined outer fiber shape or geometry. Examples of fiber types that can be used are listed below. The proportion by weight can be determined, for example, gravimetrically after dissolving the product and drying the fibers from the solvent. Solvents are known to those skilled in the art for selectively dissolving the polymer while maintaining fiber integrity. Alternatively, the fiber content can be determined using the methods mentioned above such as TGA and elemental analysis. The fiber weight fraction can furthermore preferably be 1% to 18%, particularly preferably 1.5% to 15% and very particularly preferably 2% to 12%.

The fibers have an aspect ratio of> 100. The aspect ratio describes the ratio of the depth or height of a structure to its (smallest) lateral extent. If the fiber has a varying diameter or a varying catch, the mean values over the entire fiber can be used for the aspect ratio. The fibers preferably have an aspect ratio of greater than or 200, more preferably greater than 500, and further preferably greater than 1000. Smaller aspect ratios can be disadvantageous since products containing these fibers cannot have the required mechanical anisotropy.

The fibers which can be used according to the invention have a catch of> 3 cm and <1000 cm. This fiber length range has proven to be particularly suitable for obtaining a 3D-printed product with strongly anisotropic mechanical properties. The range indicates that at least 95% of the number of fibers has a catch within the range specified above, that is to say within the range. A certain proportion of smaller fiber lengths, for example obtained by fiber breakage during production, is also according to the invention. With these fiber lengths, extremely stable 3D-printed products can be obtained which, due to the fiber properties in connection with the polymers used, show a high anisotropy in the mechanical properties. The fibers can preferably also be> 7 cm and <500 cm; furthermore preferably> 10 cm and <100 cm long.

The product is manufactured at least in part by means of an FFF (Fused Filament Fabrication) process. The extruded polymer can optionally be crosslinked in a downstream process. After crosslinking, the reaction of the polymer with water in follow a conversion of, for example, isocyanate groups to urea and / or by radiation curing and / or by tempering at temperatures at least above the glass point of the polymer. However, the shape of the product is entirely or partially carried out using a 3D printing process, with at least a region of the product which has fiber reinforcement having to have been produced using the 3D printing process. According to the invention, the “fused filament fabrication” is used as the production method, that is to say the production via molten (polymeric) filaments. It is also in the spirit of the invention that partial areas of the product were not produced by a 3D printing process. Products can thus result which have isolated one or more sections with the material properties required in the independent claim.

The product has a tensile modulus according to DIN EN ISO 527-1 measured in the area of fiber reinforcement and in the direction of the fiber symmetry axis of> 1.5 GPa. In the area of fiber reinforcement according to the invention means that the mechanical properties are measured at the points of the product which have fiber reinforcement. Samples from this area can be taken and subjected to mechanical analysis. Values obtained by measurements in areas without fiber reinforcement are not according to the invention. The measured specimen must accordingly have or contain at least one fiber. In the case of production-related scattering of the modules, the mean value according to the invention counts at three different points of the product of measured samples. The modules are collected on the finished product, i.e. after further treatment steps such as tempering / cooling / after crosslinking.

According to the invention, the axis of symmetry of a fiber is parallel to the longitudinal axis of the fiber, that is to say parallel to the fiber axis with the largest spatial fiber extension, as described above. If the fiber within the product is not aligned monotonously, the axis of symmetry of the fiber is the average of the individual segment axes of symmetry. According to the invention, the tensile modulus in the direction of the fiber symmetry axis also results for the cases in which the deviations between the measuring direction and the fiber symmetry axis are less than 20 °, preferably less than 10 °, and furthermore less than 5 °. Within these deviations, the requirements for the anisotropy and elasticity of the product can still be met. In preferred embodiments, the module in the axis of symmetry can be greater than 1.7 GPa, further preferably> 2GPa, further preferably> 3 GPa, and also preferably> 4 GPa on the finished product. Within these module sizes, high loads can be absorbed by the product. Modules smaller than 1.5 GPa can be disadvantageous because the products may not have the required mechanical stability due to their high elasticity. The product according to the invention furthermore has a tensile modulus according to DIN EN ISO 527-1 measured in the area of the fiber reinforcement and perpendicular to the fiber symmetry axis of <1.2 GPa. The measurement is carried out on the finished product, if necessary after further processing steps such as tempering / cooling / crosslinking, which can still influence the mechanical properties of the product. The tensile modulus is measured perpendicular to the fiber symmetry axis if the mean orientation of the fibers present in the specimen include an angle of greater than or equal to 75 ° and less than or equal to 105 ° to the measuring direction. The measurement takes place in the area of fiber reinforcement if the measured sample body has at least one of the fibers according to the invention. The tensile modulus can preferably also be <1.0 GPa, preferably <0.8 GPa, less than 0.6 GPa, and furthermore preferably <0.4 GPa. These limits in the tensile module have proven their worth in maintaining highly anisotropic workpieces. Modules lower than <0.05 GPa can be disadvantageous, since in these cases the products may lack the necessary strength. Higher modules can lead to a low anisotropy of the product, which is not according to the invention.

The product according to the invention also has a yield strength of> 5% measured in the area of the fiber reinforcement and perpendicular to the fiber symmetry axis in accordance with DIN EN ISO 527-1. To obtain products with the highest possible mechanical anisotropy, the yield strengths specified above have proven to be particularly advantageous. Thanks to these yield strengths, the product can be equipped with sufficient elasticity for many areas of application, so that preferred usage properties result in the application. For example, toothed splints can be easily inserted and removed again due to the high yield strength. The yield strength can also preferably be> 7%, further preferably> 9%, further preferably> 11% and likewise> 15%

In a preferred embodiment, the product can be rotationally symmetrical on at least one spatial section and the axis of symmetry of the fibers can be aligned perpendicular to the axis of symmetry of the product. The product can thus be rotationally symmetrical overall or, in the case of complex products with a plurality of shapes placed one against the other, a part of the product. Examples of these preferred embodiments are, for example, O-rings or V-belts, these structures being rotationally symmetrical and the axis of symmetry running through the center of the product. A preferred combination of materials for O-rings would be TPU / polyaramid fiber. For these products, the axis of symmetry of the fibers runs parallel to the circumference of the products and thus perpendicular to the axis of symmetry of the product. According to the invention, both axes of symmetry are perpendicular to one another in those cases if they enclose an angular range greater than or equal to 75 ° and less than or equal to 105 ° to one another. This geometric connection can lead to particularly suitable products, which are excellent strength in the load direction and high elasticity.

In a further embodiment, the product can have an aspect ratio of> 1 and the axis of symmetry of the fibers lies essentially in one plane with the product axis with the greatest extent. The products according to the invention with the anisotropic mechanical properties are particularly suitable for the production of products with asymmetrical dimensions, the mechanical fiber stabilization of the products lying in one plane with the greatest product expansion. As a result, the product can be maximally stabilized by the fiber storage. In further preferred embodiments, the product can have an aspect ratio of> 3, preferably> 5, further preferably> 10 and further preferably> 15.

Within a further characteristic, the product can have a loss factor tan d of <0.07 in the area of fiber reinforcement, measured by means of mechanical dynamic analysis (DMA) in tensile stress, and a yield strength in the direction of the fiber symmetry axis of <7% measured according to DIN EN ISO 527- 1 have. These mechanical properties of the product preferably contribute to the high strength and resilience of the product in the fiber direction. The reason for the low yield strength and the loss factor according to the invention can be seen in the combination of the fibers which can be used according to the invention and the elastic polymer. Higher yield strengths can be disadvantageous because in these cases the printed product can only show insufficient resistance to mechanical stress on the product. The loss factor can preferably be <0.06, preferably <0.05, furthermore <0.04 and further preferably <0.03. These loss factors can contribute to a particularly strong anisotropy in the mechanical properties of the product. The yield strength can be determined at 23 ° C. and the yield strength can preferably also be <3%, particularly preferably <2% and very particularly preferably <1%.

In another aspect of the product, the polymer can be a thermoplastic elastomer. Thermoplastic elastomers (TPE) are materials in which elastic polymer chains are integrated in thermoplastic material. They can be processed in a purely physical process in a combination of high shear forces, exposure to heat and subsequent cooling. Although no chemical crosslinking due to time-consuming and temperature-consuming vulcanization, as with the elastomers, is necessary, the parts manufactured have rubber-elastic properties due to their special molecular structure. A renewed exposure to heat and shear forces leads to melting and Deformation of the material. At the same time, this means that the TPE is far less thermally and dynamically resilient than standard elastomers. The TPE are therefore not a "successor product" of conventional elastomers, but an addition that combines the processing advantages of thermoplastics with the material properties of the elastomers.

In some areas, thermoplastic elastomers have physical cross-linking points (secondary valence forces or crystallites) that dissolve when exposed to heat without the macromolecules decomposing. Therefore, they can be processed much better than normal elastomers. This means that plastic waste can also be melted down and processed further. However, this is also the reason why the material properties of thermoplastic elastomers change non-linearly over time and temperature. The two main measurable physical material properties are the compression set and the stress relaxation. Compared to ethylene-propylene-diene rubber (EPDM), they have poorer material properties in short-term behavior, and the raw material is also more expensive. In the long-term behavior, however, the picture is reversed compared to EPDM.

As the processing process is basically the same as that of thermoplastic materials, similarly short cycle times are possible. In manufacturing, thermoplastic elastomers are increasingly used in automotive body seals and in components. They can be extruded, injection molded or blow molded and are usually obtained ready for use.

A distinction is made between copolymers and elastomer alloys according to the internal structure.

Copolymers are used either as statistical or as block copolymers. The former consist of a crystallizing (and thus physically crosslinking) main polymer such as. B. polyethylene, the degree of crystallization by a randomly installed along the chain comonomer such. B. vinyl acetate is reduced to such an extent that the crystallites (= the hard phase) in the finished material (in the example EVA) no longer have direct contact. They then act as isolated crosslinking points, as in conventional elastomers.

In block copolymers, the hard and soft segments are sharply separated in one molecule (e.g. SBS, SIS). With TPEs, the material separates into a continuous and a discontinuous phase below a certain temperature. As soon as the latter falls below its glass transition temperature Tg (the Tg of the continuous phase is significantly below the later application temperature), it in turn acts as a crosslinking point.

Elastomer alloys are polyblends, i.e. mixtures of finished polymers. The plastic therefore consists of several types of molecules. By different Mixing ratios and additives are available for customized materials (e.g. polyolefin elastomer made of polypropylene (PP) and natural rubber (NR) - depending on the ratio, they cover a wide range of hardness).

A distinction is made between the following groups:

• TPE-A or TPA = thermoplastic copolyamides, e.g. B. PEBAX (Arkema)

• TPE-E or TPC = thermoplastic polyester elastomers / thermoplastic copolyesters, e.g. B. Keyflex (LG Chem)

• TPE-0 or TPO = thermoplastic elastomers based on olefins, mainly PP / EPDM

• TPE-S or TPS = styrene block copolymers (SBS, SEBS, SEPS, SEEPS and MBS), e.g.

B. Kraton (Kraton Polymers), Septon (Kuraray), Styroflex (BASF), Thermolast (Kraiburg TPE) or Saxomer (PCW)

• TPE-U or TPU = thermoplastic elastomers based on urethane, e.g. B. Elastollan (BASF) or Desmopan, Texin, Utechllan (Covestro)

• TPE-V or TPV = thermoplastic vulcanizates or cross-linked thermoplastic elastomers based on olefins, mainly PP / EPDM, e.g. B. Sariink (DSM)

Thermoplastic elastomers can, for example, also be selected from the group: thermoplastic copolyamides (TPA), thermoplastic copolyesters (TPC), thermoplastic elastomers based on olefins (TPO), styrene block copolymers (TPS), thermoplastic elastomers based on urethane (TPU), cross-linked thermoplastic elastomers Olefin-based (TPV), thermoplastic elastomers based on polyvinyl chloride (PVC), thermoplastic elastomers based on silicone or a combination of at least two of these elastomers. Combinations of> 3,> 4 or> 5 of these elastomers are also possible. The elastic polymer can also contain other additives such as fillers, stabilizers and the like, but also other polymers. The total content of additives in the elastic polymer can be, for example,> 0.1% by weight to <70% by weight, preferably> 1% by weight to <50% by weight. This group of thermoplastic elastomers can greatly contribute to products with high mechanical anisotropy.

In a further preferred embodiment of the use according to the invention, the elastomer is a thermoplastic elastomer and has a melting range (DSC, differential scanning calorimetry; second heating with heating rate 20 K / min) from> 20 ° C. to <280 ° C. (preferably> 40 ° C to <250 ° C, more preferably> 50 ° C to <220 ° C), a Shore A hardness according to DIN ISO 7619-1 of> 40 to <98 (preferably> 50 to <95, more preferably> 60 to <90) and a melt volume rate (MVR) according to ISO 1133 (measured 120 ° C. above the melting point, 10 kg) of> 5 to <200 (preferably> 10 to <150, more preferred > 15 to <100) cm ^3/10 min.

In a preferred embodiment of the product, the polymer can be a polyurethane or a rubber. The rubber can be the base material and can be used before curing or vulcanization. In the art, the vulcanizates of natural and synthetic rubbers are referred to as rubbers (the majority of rubbers). (Jürgen Falbe, Manfred Regitz (ed.): CD Römpp Chemie Lexikon, Thieme, Stuttgart, 1995). This selection of polymers can lead to particularly elastic and mechanically strongly anisotropic products.

In a preferred embodiment, the thermoplastic elastomer can be a thermoplastic polyurethane elastomer.

In a further preferred embodiment of the use according to the invention, the elastomer is a thermoplastic polyurethane elastomer which can be obtained from the reaction of the components: a) at least one organic diisocyanate b) at least one compound having groups which are reactive toward isocyanate groups and having a number average molecular weight (Mn) of> 500 g / mol to <6000 g / mol and a number-average functionality of the total of the components under b) from> 1.8 to <2.5 c) at least one chain extender with a molecular weight (Mn) of 60-450 g / mol and a number-average functionality of the entirety of the chain extender under c) from 1.8 to 2.5.

For the synthesis of this thermoplastic polyurethane elastomer (TPU), the following may be mentioned as examples of the isocyanate component under a): aliphatic diisocyanates such as ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cycloaliphatic diisocyanates such as isophorone diisocyanate - Cyclohexane diisocyanate, l-methyl-2,4-cyclohexane diisocyanate and l-methyl-2,6-cyclohexane diisocyanate and the corresponding isomer mixtures, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate and 2,2'-

Dicyclohexylmethane diisocyanate and the corresponding isomer mixtures, also aromatic diisocyanates such as 2,4-tolylene diisocyanate, mixtures of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate. 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate and 2,2'-diphenylmethane diisocyanate. Mixtures of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, urethane-modified liquid 4,4'-diphenylmethane diisocyanates or 2,4'-diphenylmethane diisocyanates, 4,4'-diisocyanatodiphenylethane (1,2) and 1,5-naphthylene diisocyanate . 1,6-hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate,

Diphenylmethane diisocyanate isomer mixtures with a 4,4'-diphenylmethane diisocyanate content of more than 96% by weight and in particular 4,4'-diphenylmethane diisocyanate and 1,5-naphthylene diisocyanate. The diisocyanates mentioned can be used individually or in the form of mixtures with one another. They can also be used together with up to 15 mol% (calculated on total diisocyanate) of a polyisocyanate, but at most so much polyisocyanate may be added that a still processable product is obtained. Examples of polyisocyanates are triphenylmethane 4,4 ', 4 "triisocyanate and polyphenyl polymethylene polyisocyanates.

Examples of longer-chain isocyanate-reactive compounds under b) are those with on average at least 1.8 to 3.0 Zerewitinoff-active hydrogen atoms and a number-average molecular weight of 500 to 10,000 g / mol. In addition to amino groups, thiol groups or compounds containing carboxyl groups are included, in particular two to three, preferably two hydroxyl group-containing compounds, especially those with number-average molecular weights Mn of 500 to 6000 g / mol, particularly preferably those with a number-average molecular weight Mn of 600 to 4000 g / mol, eg polyester polyols containing hydroxyl groups, polyether polyols, polycarbonate polyols and polyester polyamides. Suitable polyester diols can be prepared by reacting one or more alkylene oxides with 2 to 4 carbon atoms in the alkylene radical with a starter molecule which contains two active hydrogen atoms bonded. Examples of alkylene oxides are: ethylene oxide, 1,2-propylene oxide, epichlorohydrin and 1,2-butylene oxide and 2,3-butylene oxide. Ethylene oxide, propylene oxide and mixtures of 1,2-propylene oxide and ethylene oxide are preferably used. The alkylene oxides can be used individually, alternately in succession or as mixtures. Examples of suitable starter molecules are water, amino alcohols, such as N-alkyl-diethanolamines, for example N-methyl-diethanolamine, and diols, such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol and 1,6-hexanediol. If appropriate, mixtures of starter molecules can also be used. Suitable polyether diols are also the hydroxyl-containing polymerization products of tetrahydrofuran. Trifunctional polyethers can also be used in proportions of 0 to 30% by weight, based on the bifunctional polyether diols, but at most in such an amount that a product which can still be processed thermoplastically is produced. The essentially linear polyether diols preferably have number average molecular weights n of 500 to 6000 g / mol. They can be used both individually and in the form of mixtures with one another.

Suitable polyester diols can be prepared, for example, from dicarboxylic acids having 2 to 12 carbon atoms, preferably 4 to 6 carbon atoms, and polyhydric alcohols. Examples of suitable dicarboxylic acids are: aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid and sebacic acid, or aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids can be used individually or as mixtures, e.g. in the form of a mixture of succinic, glutaric and adipic acids. To prepare the polyester diols, it may be advantageous to use the corresponding dicarboxylic acid derivatives, such as carboxylic acid diesters having 1 to 4 carbon atoms in the alcohol radical, carboxylic acid anhydrides or carboxylic acid chlorides, instead of the dicarboxylic acids. Examples of polyhydric alcohols are glycols having 2 to 10, preferably 2 to 6, carbon atoms, for example: Ethylene glycol, diethylene glycol, 1, 4-butanediol, 1,5-pentanediol, 1, 6-hexanediol, 1,10-decanediol,

2,2-dimethyl-l, 3-propanediol, 1,3-propanediol or dipropylene glycol. Depending on the desired properties, the polyhydric alcohols can be used alone or as a mixture with one another. Also suitable are esters of carbonic acid with the diols mentioned, in particular those with 4 to 6 carbon atoms, such as 1, 4-butanediol or 1,6-hexanediol, condensation products of w-hydroxycarboxylic acids such as w-hydroxycaproic acid or polymerization products of lactones, e.g. optionally substituted w-caprolactone. Preferred polyester diols are ethanediol polyadipates, 1,4-butanediol polyadipates, ethanediol-1,4-butanediol polyadipates, 1,6-hexanediol-neopentylglycol polyadipates, 1,6-hexanediol-1,4-butanediol polyadipates and polycaprolactones. The polyester diols preferably have number average molecular weights Mn of 450 to 6000 g / mol and can be used individually or in the form of mixtures with one another.

The chain extenders under c) have an average of 1.8 to 3.0 Zerewitinoff-active hydrogen atoms and have a molecular weight of 60 to 450 g / mol. In addition to amino groups, thiol groups or carboxyl group-containing compounds, these are understood to mean those having two to three, preferably two, hydroxyl groups.

Aliphatic diols with 2 to 14 carbon atoms, such as e.g. Ethanediol, 1, 2-propanediol, 1,3-propanediol, 1, 4-butanediol,

2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol and dipropylene glycol. However, diesters of terephthalic acid with glycols with 2 to 4 carbon atoms, for example terephthalic acid-bis-ethylene glycol or terephthalic acid-bis-1,4-butanediol, hydroxyalkylene ether of hydroquinone, for example 1,4-di (b-hydroxyethyl) hydroquinone, are also suitable. ethoxylated bisphenols, e.g. 1,4-di (b- hydroxyethyl) bisphenol A, (cyclo) aliphatic diamines, such as isophoronediamine, ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, N-methyl-propylene-1,3-diamine, N, N'-dimethylethylenediamine and aromatic diamines such as 2,4-toluenediamine, 2,6-toluenediamine, 3,5-diethyl-2,4-toluenediamine or 3,5-diethyl-2,6-toluenediamine or primary mono-, di-, tri- or tetraalkyl-substituted 4 , 4'-Diaminodiphenylmethane. Ethanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-di (β-hydroxyethyl) hydroquinone or 1,4-di (β-hydroxyethyl) bisphenol A are particularly preferably used as chain extenders. Mixtures of the chain extenders mentioned above can also be used.

Smaller amounts of triplets can also be added.

Compounds which are monofunctional to isocyanates can be used under f) in proportions of up to 2% by weight, based on TPU, as so-called chain terminators. Suitable are e.g. Monoamines such as butyl- and dibutylamine, octylamine, stearylamine, N-methylstearylamine, pyrrolidine, piperidine or cyclohexylamine, monoalcohols such as butanol, 2-ethylhexanol, octanol, dodecanol, stearyl alcohol, the various amyl alcohols, cyclohexanol and ethylene glycol monomethyl ether.

The substances which are reactive toward isocyanate should preferably be chosen so that their number-average functionality does not significantly exceed two if it is intended to produce thermoplastically processable polyurethane elastomers. If more functional connections are used, the overall functionality should be reduced accordingly by connections with a functionality <2.

The relative amounts of the isocyanate groups and isocyanate-reactive groups are preferably chosen so that the ratio is 0.9: 1 to 1.2: 1, preferably 0.95: 1 to 1.1: 1.

The thermoplastic polyurethane elastomers used according to the invention can contain up to a maximum of 20% by weight, based on the total amount of TPU, of the conventional auxiliaries and additives as auxiliaries and / or additives. Typical auxiliaries and additives are catalysts, antiblocking agents, inhibitors, pigments, dyes, flame retardants, stabilizers against the effects of aging and weather, against hydrolysis, spruce, heat and discoloration, plasticizers, lubricants and mold release agents, fungistatic and bacteriostatic substances, reinforcing agents and inorganic and / or organic fillers and mixtures thereof.

Examples of the additives are lubricants, such as fatty acid esters, their metal soaps, fatty acid amides, fatty acid ester amides and silicone compounds, and reinforcing agents, such as, for example, fibrous reinforcing materials, such as inorganic fibers, which are produced according to the prior art and can also be subjected to a size. Details on the auxiliaries and additives mentioned are the specialist literature, for example the monograph by JH Saunders and KC Frisch "High Polymers", Volume XVI, Polyurethane, Parts 1 and 2, Publisher Interscience Publishers 1962 and 1964, the paperback for plastic additives by R Gächter u. H. Müller (Hanser Verlag Munich 1990) or DE-A 29 01 774.

Suitable catalysts are the conventional tertiary amines known and known in the art, e.g. Triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N, N'-dimethylpiperazine, 2- (dimethylaminoethoxy) ethanol, diazabicyclo [2,2,2] octane and the like, and in particular organic metal compounds such as titanium acid esters, iron compounds or tin compounds such as tin diacetate, tin dioctoate, tin dilaurate or the tin dialkyl salts of aliphatic carboxylic acids such as dibutyltin diacetate or dibutyltin dilaurate or the like. Preferred catalysts are organic metal compounds, especially titanium acid esters, iron and tin compounds. The total amount of catalysts in the TPU used is generally about 0 to 5% by weight, preferably 0 to 2% by weight, based on the total amount of TPU.

Polyurethane elastomers suitable according to the invention can be, for example, 2-component cast elastomers. They can be obtained by known methods from a reaction mixture comprising: a) at least one organic polyisocyanate b) at least one compound having groups which are reactive toward isocyanate groups and having a number average molecular weight (Mn) of> 500 g / mol to <6000 g / mol and at least a number-average functionality of the total of the components of> 2.1 c) optionally at least one chain extender with a molecular weight (Mn) of 60-450 g / mol.

For details regarding polyisocyanates and NCO-reactive compounds, reference is made to the above statements.

In a further preferred embodiment of the use according to the invention, the elastomer is a thermoplastic elastomer and has a melting range (DSC, differential scanning calorimetry; 2nd heating with heating rate 5 K / min.) Of> 20 ° C to <100 ° C and has one Amount of the complex viscosity Ih * I (determined by viscometry measurement in the melt with a plate / plate oscillation shear viscometer at 100 ° C. and a shear rate of 1 / s) from> 10 Pas to <1000000 Pas.

This thermoplastic elastomer has a melting range of> 20 ° C to <100 ° C, preferably from> 25 ° C to <90 ° C and more preferably from> 30 ° C to <80 ° C. In the DSC measurement to determine the melting range, the material is subjected to the following temperature cycle: 1 minute at -60 ° C, then heating to 200 ° C at 5 Kelvin / minute, then cooling to -60 ° C at 5 Kelvin / minute, then 1 minute at -60 ° C, then heating to 200 ° C at 5 Kelvin / minute.

It is possible that the temperature interval between the start of the melting process and the end of the melting process, as can be determined according to the DSC protocol above, is <20 ° C., preferably <10 ° C. and more preferably <5 ° C.

This thermoplastic elastomer also has an amount of the complex viscosity Ih * I (determined by viscometry measurement in the melt with a plate / plate oscillation viscometer according to ISO 6721-10 at 100 ° C. and a shear rate of 1 / s) of> 10 Pas to < 1000000 Pas on. Ih * I is preferably> 100 Pas to <500000 Pas, more preferably> 1000 Pas to <200000 Pas.

The amount of the complex viscosity Ih * I describes the ratio of the viscoelastic modules G '(storage module) and G "(loss module) to the excitation frequency w in a dynamic mechanical material analysis:

This thermoplastic elastomer is preferably a thermoplastic polyurethane elastomer. In a further preferred embodiment of the product according to the invention, the elastomer is a thermoplastic polyurethane elastomer which can be obtained from the reaction of a polyisocyanate component and a polyol component, the polyol component comprising a polyester polyol which has a pour point (ASTM D5985) of> 25 ° C.

If appropriate, diols in the molecular weight range from> 62 to <600 g / mol can furthermore be used as chain extenders in the reaction to give this polyurethane.

This polyisocyanate component can comprise a symmetrical polyisocyanate and / or a non-symmetrical polyisocyanate. Examples of symmetrical polyisocyanates are 4,4 '-MDI and HDI.

In the case of non-symmetrical polyisocyanates, the steric environment of an NCO group in the molecule is different from the steric environment of another NCO group. An isocyanate group then reacts faster with groups that are reactive toward isocyanates, for example OH groups, while the remaining isocyanate group is less reactive. A consequence of the non-symmetrical structure of the polyisocyanate is that the structure of these polyisocyanates Polyurethanes also have a less straight structure.

Examples of suitable non-symmetrical polyisocyanates are selected from the group comprising: 2,2,4-trimethyl-hexamethylene diisocyanate, ethyl ethylene diisocyanate, non-symmetrical isomers of dicyclohexyl methane diisocyanate (H12-MDI), non-symmetrical isomers of 1,4-diisocyanatocy clohexane, non- symmetrical isomers of 1,3-diisocyanatocyclohexane, non-symmetrical isomers of 1,2-diisocyanatocyclohexane, non-symmetrical isomers of 1,3-diisocyanatocyclopentane, non-symmetrical isomers of 1,2-diisocyanatocyclopentane, non-symmetrical isomers of 1,2 -Diisocyanatocyclobutane, 1-isocyanatomethyl-3-isocyanato-l, 5,5-trimethylcyclohexane (isophorone diisocyanate, IPDI), 1-methyl-2,4-diisocyanato-cyclohexane, l, 6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane, 5-isocyanato-l- (3-isocyanatoprop-l-yl) -l, 3,3-trimethyl-cyclohexane, 5-isocyanato-l- (4-isocyanatobut -l-yl) -l, 3,3-trimethyl-cyclohexane, l-isocyanato-2- (3-isocyanatoprop-l-yl) -cyclohexane, l-isocyanate to-2- (2-isocyanatoeth-l-yl) -cyclohexane, 2-heptyl-3,4- bis (9-isocyanatononyl) - 1-pentyl-cyclohexane, norbonane diisocyanatomethyl, 2,4'-diphenylmethane diisocyanate (MDI) , 2,4- and 2,6-tolylene diisocyanate (TDI), derivatives of the listed diisocyanates, in particular dimerized or trimerized types, or a combination of at least two of these.

4,4'-MDI or a mixture containing IPDI and HDI as the polyisocyanate component are preferred.

This polyol component can have a polyester polyol which has a pour point (No Flow Point, ASTM D5985) of> 25 ° C, preferably> 35 ° C, more preferably> 35 ° C to <55 ° C. To determine the pour point, a measuring vessel is set with the sample in a slow rotation (0.1 rpm). A flexibly mounted measuring head dips into the sample and is moved away from its position when the pour point is reached due to the sudden increase in viscosity, the resulting tilting movement triggers a sensor.

Examples of polyester polyols which can have such a pour point are reaction products of phthalic acid, phthalic anhydride or symmetrical a, ro-C4 to C10 dicarboxylic acids with one or more C2 to C10 diols. They preferably have a number average molecular weight Mn of> 400 g / mol to <6000 g / mol. Suitable diols are in particular monoethylene glycol, 1,4-butanediol, 1,6-hexanediol and neopentyl glycol.

Preferred polyester polyols are given below with their acid and diol components: adipic acid + monoethylene glycol; Adipic acid + monoethylene glycol + 1,4-butanediol; Adipic acid + 1,4-butanediol; Adipic acid + 1,6-hexanediol + neopentyl glycol; Adipic acid + 1.6- Hexanediol; Adipic acid + 1,4-butanediol + 1,6-hexanediol; Phthalic acid (anhydride) + monoethylene glycol + trimethylolpropane; Phthalic acid (anhydride) + monoethylene glycol. Preferred polyurethanes are obtained from a mixture containing IPDI and HDI as the polyisocyanate component and a polyol component containing a previously mentioned preferred polyester polyol. The combination of a mixture comprising IPDI and HDI as the polyisocyanate component with a polyester polyol composed of adipic acid + 1,4-butanediol + 1,6-hexanediol is particularly preferred to form the polyurethanes.

It is further preferred that these polyester polyols have an OH number (DIN 53240) of> 25 to <170 mg KOH / g and / or a viscosity (75 ° C, DIN 51550) of> 50 to <5000 mPas.

An example is a polyurethane which is obtainable from the reaction of a polyisocyanate component and a polyol component, the polyisocyanate component comprising an HDI and IPDI and the polyol component comprising a polyester polyol which comprises the reaction of a reaction mixture comprising adipic acid and 1,6-hexanediol and 1,4-butanediol is available with a molar ratio of these diols of> 1: 4 to <4: 1 and which has a number average molecular weight Mn (GPC, against polystyrene standards) of> 4000 g / mol to <6000 g / mol. Such a polyurethane can have an amount of the complex viscosity Ih * I (determined by viscometry measurement in the melt with a plate / plate oscillation viscometer according to ISO 6721-10 at 100 ° C. and a shear rate of 1 / s) of> 4000 Pas to <160000 Have Pas.

Other examples of suitable polyurethanes are:

Largely linear, terminal hydroxyl-containing polyester polyurethanes as described in EP 019 294 6 Al, prepared by reacting a) polyester diols with a molecular weight above 600 and optionally b) diols in the molecular weight range from 62 to 600 g / mol as chain extenders with c) aliphatic diisocyanates Maintaining an equivalent ratio of hydroxyl groups of components a) and b) to isocyanate groups of component c) of 1: 0.9 to 1: 0.999, with component a) being based on at least 80% by weight of polyester diols of the molecular weight range 4000 to 6000 of (i) adipic acid and (ii) mixtures of 1,4-dihydroxybutane and 1,6-dihydroxyhexane in a molar ratio of the diols of 4: 1 to 1: 4.

In the aforementioned polyester polyurethanes, it is preferred that component a) is 100% consists of a polyester diol in the molecular weight range 4000 to 6000, in the preparation of which a mixture of 1,4-dihydroxybutane and 1,6-dihydroxyhexane in a molar ratio of 7: 3 to 1: 2 was used as the diol mixture.

In the aforementioned polyester polyurethanes, it is further preferred that component c) contains IPDI and furthermore HDI.

In the aforementioned polyester polyurethanes, it is further preferred that alkane diols, selected from the group consisting of: 1,2-dihydroxyethane, 1,3-dihydroxy propane, 1,4-dihydroxybutane, 1,5-dihydroxypentane, are used as component b) in their preparation , 1,6-dihydroxyhexane or a combination of at least two of them, in an amount of up to 200 hydroxyl equivalent percent, based on component a), have also been used.

It is also possible that the thermoplastic elastomer after heating to 100 ° C and cooling to 20 ° C at a cooling rate of 4 ° C / min in a temperature interval of 25 ° C to 40 ° C for> 1 minute (preferably> 1 minute up to <30 minutes, more preferably> 10 minutes to <15 minutes), a storage module G '(determined at the prevailing temperature with a plate / plate oscillation viscometer according to ISO 6721-10 at a shear rate of 1 / s) of> 100 kPa to <1 MPa and after cooling to 20 ° C and storage for 20 minutes a storage module G '(determined at 20 ° C with a plate / plate oscillation viscometer according to ISO 6721-10 at a shear rate of 1 / s) of> 10 MPa.

Usable materials can consist of or contain natural or synthetic rubber, for example.

The synthetic rubber can preferably be selected from the group consisting of thiokol rubber or rubber, EVA (ethylene vinyl acetate copolymer rubber), FPVC (flexible polyvinyl chloride rubber), FZ rubber (fluorinated polyphosphazene rubber), GPO (propylene oxide rubber), HNBR (hydrogenated nitrile butadiene) Rubber), HSN (highly saturated nitrile rubber), ACM (acrylic rubber), VAMAC (polyethylene-co-acrylic-acrylic acid rubber), PNR (polynorborane rubber), PZ (polyphosphazene rubber), ABR (acrylate-butadiene rubber), ACM rubber (copolymer of ethyl or other acrylates with a small amount of a vulcanizing monomer, AECO rubber (terpolymer of allyl glycidyl ether, ethylene oxide and epichlorohydrin), AEM rubber (copolymer of ethyl or other acrylates and ethylene), AFMU rubber (terpolymer of tetrafluoroethylene, trifluoronitro tromofluorobutomethyl) and , ANM rubber (copolymer of ethyl or other acrylates and acrylonitrile), AU (polyester urethane rubber), BIIR (bromine-isobutene-isoprene n rubber (bromobutyl rubber), BR (butadiene rubber), CFM (polychlorotrifluoroethylene rubber), CIIR (chloro-isobutene Isoprene rubber (chloro rubber), CM (chlorinated polyethylene rubber), CO (epichlorohydrin rubber), CR (chloroprene rubber), CSM (chlorosulphonated polyethylene rubber), ECO (ethylene oxide and epichlorohydrin copolymer rubber), EAM (ethylene-vinyl acetate copolymer rubber) , EPDM (terpolymer of ethylene, propylene and a diene with a remaining amount of unsaturated diene in the side chain of the rubber), EPM ethylene-propylene copolymer rubber), EU (polyether urethane rubber), FFKM (perfluoro rubber of the polymethylene type with all Polymer chain substituents (either fluorine, perfluoroalkyl or perfluoroalkoxy groups), FKM (polymethylene-type fluorine rubber with fluorine and perfluoroalkoxy group substituents on the main chain), FVMQ (silicone rubber with fluorine, vinyl and methyl substituents on the polymer chain), GPO (polypropylene oxide rubber), IIR (isobutene-isoprene rubber (butyl rubber)), IM (polyisobutene rubber), IR (isoprene rubber (synthetic)), MQ (silicone rubber with only methyl substituents) on the polymer chain), NBR (nitrile-butadiene rubber (nitrile rubber)), NIR (nitrile-isoprene rubber), PBR (pyridine-butadiene rubber), PMQ (silicone rubber with only methyl and phenyl groups on the polymer chain), PSBR (pyridine-styrene-butadiene rubber), PVMQ (silicone rubber with methyl, phenyl and vinyl substituents on the polymer chain), Q (rubber with silicone in the polymer chain), SBR (styrene-butadiene rubber), T (rubber with sulfur in the polymer chain (without CR-based copolymers)), VMQ (silicone rubber with methyl and vinyl substituents in the polymer chain), XNBR (carboxyl-nitrile butadiene rubber (carboxynitrile rubber)), XSBR (carboxyl-styrene butadiene rubber).

The rubber can preferably also consist of two components or contain these. The first material or the further material can preferably have a component from a group consisting of polyacrylic rubber (ACM), styrene-butadiene rubber (SBR), polysiloxane (SI), vinyl methyl silicone (VMQ), nitrile rubber (NR), Hydrogenated nitrile rubber, (HNBR), carboxylated nitrile rubber (XNBR), carboxylated hydrogenated nitrile rubber (XHNBR), ethylene propylene copolymer rubber (EPDM), polychloroprene rubber (CR), Vamac, fluorinated rubber (FKM), isobutylene rubber (IIR) , Polybutadiene rubber (BR) or a mixture of at least two of these components.

In a preferred embodiment, the synthetic rubber may contain further additives selected from the group consisting of organic or inorganic fillers, a plasticizer, a metal oxide, anti-degradation agents (against oxidation, hydrolysis, yellowing, ozone attack, etc.), processing aids, silanes, a coagent and a curing agent or a combination of at least two of them. Examples of an inorganic filler are carbon black N330 or silicon dioxide, cut glass fibers / crushed carbon fibers / crushed natural fibers, phthalate esters such as dioctyl phthalate for a plasticizer, ZnO for a metal oxide, and Irganox 1010 (pentaerythritol for an anti-degradation agent) Tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate)), for a processing aid stearic acid, as coagent polybutadiene, triallyl isocyanurate (TAIC) or mixtures thereof, for a crosslinking agent di (tert-butylperoxyisopropyl ) benzene like Perkadox 14/40.

After vulcanization or hardening of the rubber, it can be referred to as rubber. In the literature and in the designation of raw materials, the term rubber and rubber is often used synonymously. It is essential that the raw materials according to the invention in the uncrosslinked, uncured, uncured state are brought into the desired shape by means of an additive manufacturing process and are only cured, crosslinked, vulcanized in a subsequent process step, usually by temperature storage.

In a preferred embodiment of the product, the fibers can be selected from the group consisting of glass, carbon, basalt, polyester, polyethylene, polyurethane, polyamide, polyaramid, metal, cellulose fibers or mixtures thereof. In a special embodiment, the polymer and the fiber belong to the same polymeric material class, the processing of the fiber in the additive manufacturing process, however, always taking place below the melting temperature Tm of the fiber. These fibers are able to provide sufficient mechanical strength of the products and also provide the desired mechanical anisotropy of the product. Organic fibers suitable according to the invention are aramid fibers, carbon fibers, polyester fibers, nylon fibers, rayon and plexiglass fibers. Natural fibers suitable according to the invention are flax fibers, hemp fibers, wood fibers, cotton fibers, cellulose fibers and sisal fibers. In a special embodiment of the application, the fibers are transparent to visible light. This is particularly advantageous if, in the context of the component according to the invention, the component load, component integrity and component properties are to be measured along the fiber by means of light interference measurement before and / or during use of the component.

According to a preferred embodiment of the invention, a fiber selected from the group consisting of glass fibers, aramid fibers, basalt fibers, carbon fibers and mixtures thereof can be used. According to a particularly preferred embodiment of the invention, glass fibers and / or carbon fibers, in particular glass fibers, are used as the fibrous fillers.

The fiber can furthermore preferably be selected from the group consisting of glass, polyester, polyurethane, polyamide fibers and mixtures thereof.

In a further particular embodiment, fibers of different material classes according to the invention can be used side by side. In a further particular embodiment, fibers according to the invention of a length> 3 cm and fibers according to the invention of a length of <3 cm can be used side by side.

According to the invention, fibers of all material classes and lengths can be used side by side as long as at least the sum of fibers according to the invention with a fiber length> 3 cm exceeds a weight fraction of 1.5% and the object according to the invention has the claimed anisotropic properties with respect to the module.

Also preferred for the product, the difference in the refractive index ARI of the fibers and the polymer can be less than or equal to 0.1 and the polymer can be a transparent polymer with light transmission measured in a UV-VIS spectrometer on a sample with a thickness of 1 mm in the wavelength range from 400-800 nm of> 50%. The products according to the invention can advantageously also be distinguished in that they are essentially transparent. This can be advantageous in cases where "invisible" products, such as dental splints, are desired. Due to the match between fiber material and polymer, the available products are highly transparent and cannot be seen in their application.

According to a further embodiment, the ratio between the length of the product axis with the greatest extension and the average of the fiber length is in a range from> 0.5: to <10: 1. This ratio is preferably> 0.9: 1 to <10: 1 and more preferably> 1: 1 to <10: 1. The longer the fibers are relative to the product, the higher the tensile modulus in the fiber direction is to be expected. Fiber lengths larger than the product itself can be achieved by depositing continuous fibers from an FDM (FFF) print head, for example in the additive manufacturing of O-rings or toothed belts.

The product according to the invention can be produced by simultaneously, successively or alternately depositing a thermoplastic polymer and one or more fibers with a length of greater than or equal to 3 cm in one product in an FFF process at a temperature of> 60 ° C. This process has proven itself for the construction of 3D printed products with strong anisotropic mechanical properties. The method does not have to be used to build up the entire fiber-reinforced product. It is sufficient that only a part of the product is obtained via the above-mentioned procedure. The latter can be done, for example, by changing an existing component by depositing a fiber-reinforced layer on this component during and after an additive manufacturing process. The FFF is a melt stratification process. The term “melt layering process” denotes a manufacturing process from the field of additive manufacturing, with which a workpiece is built up layer by layer, for example from a meltable plastic. The plastic can be used with or without other additives such as fibers. Machines for the FFF are part of the Machine class of 3D printers. This process is based on the liquefaction of a wire-shaped plastic or wax material by heating. When it cools down, the material solidifies. The material is applied by extrusion with a heating nozzle that can be moved freely in relation to a production level. Either the production level can be fixed and the nozzle can be moved freely or a nozzle can be fixed and a substrate table (with a production level) can be moved or both elements, nozzle and production level, can be moved. The speed at which the substrate and nozzle can be moved relative to one another is preferably in a range from 1 to 200 mm / s. Depending on the application, the layer thickness is in a range of 0.025 and 1.25 mm, the exit diameter of the material jet (nozzle outlet diameter) from the nozzle is typically at least 0.05 mm.

In layer-by-layer model making, the individual layers combine to form a complex part. The structure of a body is usually carried out by repeating, one line at a time, one working level (forming a layer) and then shifting the working level "stacking" upwards (forming at least one further layer on the first layer), so that a shape is created layer by layer. The outlet temperature of the substance mixtures from the nozzle can be, for example, 80 ° C to 420 ° C. It is also possible to heat the substrate table and / or the installation space, for example to 20 ° C. to 250 ° C. This can prevent the applied layer from cooling too quickly, so that a further layer applied thereon sufficiently connects to the first layer.

According to a further embodiment, the product is a seal, a membrane, a drive belt, a pressure hose, an orthopedic prosthesis, an orthopedic aid or a tooth correction splint.

The products according to the invention are particularly advantageous for applications with asymmetrical loading scenarios, where the products must either have good tough-elastic properties or must have a reversible dynamic deformability in at least one spatial direction over many cycles, while at the same time maintaining high dimensional stability in at least one orthogonal spatial direction. Preferred applications are, for example, seals that seal under compression but should have a high resistance to deformation perpendicular to the compression force (to prevent the seal from extruding in the case of seals in the high-pressure range), but at the same time must have a high degree of installation flexibility. Typical examples of this are sealing rings (O-rings, groove rings, flange seals, gas tests and other products with sealing functions). Other preferred applications are drive belts of any format, which have a high dynamic flexibility perpendicular to the fiber direction, but should be as stable in length as possible in the fiber direction. Typical examples are, for example, drive belts, toothed belts, V-belts, drive belts, square belts, flat belts, automatic clutch belts, conveyor belts, as are often used in transportation and power transmission applications.

Other preferred applications are tooth correction rails, which must have a high degree of flexibility and toughness perpendicular to the fiber direction in order to be able to be used and removed safely, but should be as dimensionally stable as possible in the fiber direction or tooth correction direction.

Other preferred applications are orthopedic support elements, which have a high flexibility perpendicular to the fiber direction, but should be as stable in length as possible in the fiber direction: typical examples are corsets, support bandages, prostheses or shoe soles.

Other preferred applications are pressure hoses, which have a high flexibility perpendicular to the fiber direction, but should be as stable in length as possible in the fiber direction: typical examples are common pneumatic hoses and air springs. In this and in other cases with a loading direction perpendicular to the main axis of expansion or axis of symmetry of the component, it is often advantageous if fiber layers cross, preferably at an angle of 25 ° to 65 °, a preferred reinforcement being obtained radially to the axis of symmetry. This configuration can largely maintain the mobility and elasticity in the axis of symmetry.

Further advantages and advantageous configurations of the objects according to the invention are illustrated by the drawings and explained in the following description. It should be noted that the drawings are only descriptive and are not intended to limit the invention. They show:

Fig. 1 shows a possible product in the sense of the invention. An air spring produced according to the invention via 3D printing is shown in the top view;

Fig. 2 shows a possible product in the sense of the invention. An air spring produced according to the invention via 3D printing is shown in a sectional view;

Fig. 3 shows a possible product in the sense of the invention. Shown is a sealing element according to the invention produced by 3D printing with an embedded continuous fiber; Fig. 4 shows a possible product in the sense of the invention. An orthopedic dental splint with visible fiber reinforcement manufactured according to the invention via 3D printing is shown;

Fig. 5 shows a possible product in the sense of the invention. A transparent orthopedic dental splint with optically adapted fiber reinforcement manufactured according to the invention via 3D printing is shown;

Fig. 6 shows a possible product in the sense of the invention. The section through an inventive 3D-printed toothed belt with integrated fiber reinforcement is shown;

Fig. 7 shows a possible configuration for storing a fiber according to the invention in the method according to the Invention.

1 and 2 show 3D-printed fuft springs (1) according to the invention, the membrane (3) of the fuft springs (1) in particular being produced by 3D printing and having fibers embedded in an elastomer, for example a thermoplastic elastomer. The Fuftfeder is a combination of non-3D printed parts (2) and the 3D printed membrane (3). These fibers can be installed in the membrane (3) either in one direction or crosswise in the form of a fabric or scrim. The fibers run inside the membrane and would “look out” at the cut edge in the sectional drawing. The spring (1) can be inflated from the inside and thereby straighten up, changing the volume without significantly changing the enveloping surface (membrane). The membrane (1) is therefore not stretched or is only stretched to an insignificant extent. The high mechanical strength and the high elasticity result from the anisotropic mechanical properties of the material with the embedded fibers. In the scope of the membrane (3) there is therefore a high mechanical strength (this results in a high pressure resistance), the elastic properties predominating towards the materials (2) not according to the invention. Optionally, the spring can also be manufactured using a 3D printing process. The membrane (3) of the air spring (1) can be constructed, for example, from a combination of a thermoplastic elastomer with embedded polyamide fibers. However, it is also possible to use polychloroprene rubber and polyamide fibers or thermoplastic polyurethanes and polyaramid fibers for this construction.

FIG. 3 shows a 3D-printed sealing element (4) with non-fiber-reinforced areas (6) and an endless fiber (5) embedded therein. The continuous fiber (5) is completely embedded in the sealing element, which consists for example of an elastomer. Due to the fiber embedding (5) there are high mechanical strengths in the almost direction of later use with only a small expansion of the sealing element. In a direction perpendicular to this, however, the sealing element is clearly elastic, so that it is well embedded in those to be sealed Is given. This can increase the durability of the sealing element and enables safe operation under "less favorable" environmental conditions. The sealing element can, for example, consist of or contain 3D-printed thermoplastic polyurethanes with embedded polyaramid fibers.

FIG. 4 shows an orthopedic dental splint (7) 3D-printed according to the invention with fiber material (8) embedded in an elastomer. The fibers (8) are embedded in the load direction of the application and thus enable a reproducible and high pressure on the teeth to correct the tooth positions. Perpendicular to the fiber / load direction, the toothed splint (7) is extremely elastic due to the construction according to the invention, so that a simple insertion of the toothed splint (7) is ensured. This can increase the comfort for the user. The toothed splint can be constructed, for example, from TPU with embedded glass fibers or from thermoplastic silicone with glass fibers embedded therein.

FIG. 5 also shows an orthopedic dental splint (10), which is 3D-printed according to the invention, made of an elastomer with embedded fiber material (11), which can result in an optical match based on the optical properties of the fiber material and the optical properties of the polymer, which matches the fiber material not visible embedded in the polymer material. The tooth splint can be easily positioned on the bit (9) due to the elastic properties of the material. This configuration can contribute to the tooth splint being less visible and being worn more frequently by the user.

FIG. 6 shows a schematic section through a toothed belt (12) made of an elastomer and 3D-printed according to the invention. Perpendicular to the axis of symmetry of the toothed belt (12), i.e. perpendicular to the normal vector of the contact surface, fibers (13) are embedded within the toothed belt, which significantly increase the mechanical strength of the toothed belt. Perpendicular to the axis of symmetry of the fibers (13), that is to say to the outside of the toothed belt (12), the toothed belt (12) has clearly elastic properties which can increase the longevity of the material. Possible material combinations for this application would be, for example, TPU with embedded carbon fibers or hydrogenated nitrile rubber / carbon fibers.

FIG. 7 schematically shows a possible structure for carrying out the method according to the invention. It is shown that a fiber material (18) is deposited from a reservoir (15), between two layers of melted elastomer (17, 19). This diagram shows that the melted elastomer (17, 19) comes from two different templates (14, 16). However, it is also possible for only one nozzle to deposit the elastomer (17, 19) and for the fiber material (18) to be embedded by repeated application from only one of the nozzles (14, 16).

Claims

1. Fiber-reinforced, 3D printed elastic product (1, 3, 4, 7, 10, 12), characterized in that the product has a weight fraction of> 50% of a polymer with an average molecular weight (M _n ) of> 5,000 g / mol , measured by GPC, and a weight fraction of> 0.5% and <20% of one or more fibers (5, 8) with an aspect ratio of> 100 and a length of> 3 cm and <1000 cm, the product at least is produced proportionally by means of an FFF ("Fused Filament Fabrication") process, the product being in the area of fiber reinforcement and in the direction of

Fiber symmetry axis has a tensile modulus measured according to DIN EN ISO 527-1 of> 1.5 GPa, whereby the product has a tensile modulus measured according to DIN EN ISO 527-1 of <1.2 GPa perpendicular to the fiber symmetry axis, and the Product in the area of fiber reinforcement and perpendicular to the fiber symmetry axis has a yield strength of> 5% measured according to DIN EN ISO 527-1.

2. Product according to claim 1, wherein the product is rotationally symmetrical on at least one spatial section and the axis of symmetry of the fibers (5, 8) are aligned perpendicular to the axis of symmetry of the product.

3. Product according to one of the preceding claims, wherein the product

Has aspect ratio of> 1 and the axis of symmetry of the fibers (5, 8) lies essentially in one plane with the product axis with the greatest extent.

4. Product according to one of the preceding claims, wherein the product in the area of fiber reinforcement a loss factor tan d of <0.07, measured by means of mechanical dynamic analysis (DMA) in tensile stress, and a yield strength in the direction of

Has an axis of symmetry of <7% measured according to DIN EN ISO 527-1.

5. Product according to one of the preceding claims, wherein the polymer is a thermoplastic elastomer.

6. Product according to one of the preceding claims, wherein the polymer is a polyurethane or is a rubber.

7. Product according to one of the preceding claims, wherein the fibers (5, 8) are selected from the group consisting of glass, carbon, basalt, polyester, polyethylene, polyurethane, polyamide, polyaramide, metal, Cellulose fibers or mixtures thereof. 8. Product according to one of the preceding claims, wherein the difference in

Refractive index ARI of the fibers (5,

8) and the polymer is less than or equal to 0.1 and the polymer is a transparent polymer with a light transmission measured in a UV-VIS spectrometer on a sample with a thickness of 1 mm in the wavelength range of 400-800 nm of> 50%.

9. Product according to one of the preceding claims, wherein the ratio between the

Catches of the product axis with the greatest extension and the average fiber length is> 0.5: 1 to <10: 1.

10. Product according to one of the preceding claims, wherein the product is a seal, a membrane, a drive belt, a pressure hose, an orthopedic prosthesis, an orthopedic aid or a tooth correction splint.