EP2904037A1

EP2904037A1 - Composite materials for use in injection moulding methods

Info

Publication number: EP2904037A1
Application number: EP13773755.7A
Authority: EP
Inventors: Martin Maikisch; Volker BRINKE
Original assignee: MPLAST GmbH
Current assignee: MPLAST GmbH
Priority date: 2012-10-08
Filing date: 2013-10-07
Publication date: 2015-08-12
Also published as: US20150291792A1; JP2015530472A; DE212013000158U1; KR20150087217A; EP2716692A1; CH708581B1; WO2014056854A1; CN105008437A

Abstract

A composite material containing a polymer matrix component and filler components in particle form comprises: 20-60% v/v of a thermoplastic polymer; 15-60% v/v of a first filler component in particle form, wherein said first filler component is selected from the group consisting of powdered metals, metal oxides, covalent carbides, metal-like carbides or mixes of such powders; 5-30% v/v of a second filler component in particle form, wherein said second filler component is an inorganic and/or mineral material in powder form; and 1-15% v/v of an adhesive agent.

Description

VERBU NDWERKSTOFFE FOR USE IN INJECTION MOLDING

Field of engineering

The invention relates to composite materials with polymeric matrix and inorganic fillers.

State of the art

For the cost-efficient production of workpieces made of plastics in large series, the plastic injection molding process has proven itself. It allows the production of parts with high accuracy and / or high production rate. With suitable injection molds complicated geometries are possible, as well as the production of internal threads and other undercut structures. Also feasible is the production of components from different types of plastics in a single operation.

The strength of workpieces produced by injection molding results from the plastic composition used. The plastics used must be thermoplastic, so that they can be introduced as a liquid melt under high pressure in the injection mold, where they then solidify. For injection molding, for example, the thermoplastic polymers polypropylene PP, polymethylmethacrylate PMMA, polycarbonate PC, polystyrene PS, acrylonitrile-butadiene-styrene copolymer ABS, polyamide PA, polyoxymethylene POM, but also polyester and polyvinyl chloride PVC are used. By adding suitable functional fillers, the properties of plastics, such as elasticity and mechanical strength, can be influenced. Functional fillers such as glass fibers and wollastonite serve among others to improve the stiffness and flexural strength of polyesters, polyamides and polypropylenes. Likewise, such fillers are used in thermosetting reaction resins such as epoxy resins in order to avoid stress cracks caused by shrinkage.

The use of plastic components may not be possible or desirable for certain applications for a variety of reasons. For example, the achievable mechanical strength of plastic parts may not be sufficient for certain applications. In other cases, such as high-priced consumer products, plastic components are undesirable despite comparable properties because consumers traditionally associate plastics with low-cost products.

Metallic materials have several advantages over plastics. For metallic materials there are various methods for cost-efficient production of large series, for example the die-casting process. In this case, the liquid molten metal, for example aluminum, magnesium or zinc, is forced under high pressure into a reusable mold, where it solidifies.

Due to the limited possibilities with respect to the plastic injection molding options with respect to the mold, the production of elaborately shaped workpieces with metal die casting is more complicated, since, among other things, more post-processing steps may be necessary. With the die-casting process, for example, the direct production of internal threads is not possible, but it must be poured corresponding steel cores, which are then removed in a further operation again. Epoxy resin prepolymers with metal powder as filler are known (so-called "metal filled epoxies") .The resulting compositions can be used as a hardenable material, for example for repairing metal workpieces or for printing conductors on printed circuit boards are not suitable for the injection molding process.

Also known are thermoplastic polymers with metal powder as a filler. However, these have only a low mechanical strength. Areas of application are, for example, rapid prototyping processes, in which polyamide filled with aluminum powder is laser-sintered in layers. From EP 01 85783 A1 a thermoplastic composition for the production of radio-frequency-shielded housings for electronic devices is known. The composition consists of a thermoplastic polymer, coarse metal flakes, electrically conductive fibers and electrically conductive carbon powder.

JP 63205362 also discloses a thermoplastic composition for producing radio frequency shielding components consisting of thermoplastic polymer, particles of a very low melting point metal alloy distributed in the polymer and glass fibers as filler. Polymer / filler pellets and flakes of a (Pb-Sn-Sb) alloy are mixed together and extruded, whereby the metal melts at the extrusion temperature and, due to the mixing, is correspondingly finely dispersed in the polymer. The soft metal alloy has a low mechanical stability.

JP 2006096966 shows a thermoplastic composition for the production of radio-frequency shielding components. Bundles of fine steel fibers and glass fibers are stretched, soaked with nylon 66 polymer, extruded, and pelletized with about 1 2 mm length. These fiber / nylon pellets and normal nylon pellets are extruded together in a weight ratio of about 1: 1. The long fiber lengths make the composite unsuitable for finer structures. Also known composites consisting of hard ferrite and thermosetting or thermoplastic polymers, for the production of permanent magnets, which also have only a comparatively low mechanical strength.

Accordingly, there is a need to combine the advantages of the die casting method and the injection molding method, or to make such production methods accessible to metal, for which die casting is not possible.

Object of the invention

The object of the invention is to provide a material which does not have the above-mentioned and other disadvantages. In particular, such a material should be processable by the injection molding process. After processing, the material should have properties that are as metal-like as possible, for example in terms of strength, conductivity, specific weight and appearance.

These and other objects are achieved by composite materials according to the invention, inventive workpieces and semi-finished products of such composite materials according to the invention, kits according to the invention for producing such composite materials, uses according to the invention of such composite materials, and inventive methods for producing such composite materials, according to the independent claims. Further preferred embodiments are given in the dependent claims. Presentation of the invention

A composite material according to the invention comprising a polymeric matrix component and a particulate filler component comprises 20-60% by volume, preferably 20-50% by volume, of a thermoplastic polymer; 1 5-60 vol.% Of a first particulate filler component, said first filler component being selected from the group consisting of powdered metals, metal oxides, covalent carbides, metalloid carbides, or mixtures of such powders; 5-30 vol.% Of a second particulate filler component, said second filler component being an inorganic and / or mineral material in powder form; and 1 - 1 5% by volume of a coupling agent.

The volume fraction Vj is calculated from the weight fraction nn, the respective component i of a particular composition, divided by the specific gravity of the component p _{i (} ie: Vj = m, / p ,.

The relative volume fraction (vol.%) Is defined as r _{V | j} = V, / V _tota,, the relative weight fraction (wt.%) As r _mi = mm _tota i. The formula for converting a relative weight fraction into a relative volume fraction is then: r _Vj = V; / Σ _η V _n = (m, / _Pi ) / Σ _η (m _n / p _n ) = (r _mj * m _total / ρ,) / Σ _η (r _{m, n} * m _total / p _n )

(r _m, i / Pi) / Σ _η (r _{m, n} / p _n ) (I) or vice versa from a relative volume fraction into a relative weight fraction: r _mii = m, / Σ _η m _n = (V, * _Pi ) / Σ _η (V _n * p _n ) = (r _VJ * V _total * _Pi ) / Σ _η (r _{v, n} * V _total * _Pn )

(II) As used herein, the term "metal" refers to both pure metals and alloys of metals The term "polymer" refers to both pure polymers and copolymers and polymer blends.

Advantageously, the proportion of the thermoplastic polymer 33-44 vol.%, And / or the proportion of the first filling component 29-51 vol.%, And / or the proportion of the second filling component 8-21 vol.%, And / or the proportion of Adhesive 6-9 vol.%.

In an advantageous embodiment of such a composite material according to the invention, the first filler component contains a powdered metal selected from the group consisting of bronze, brass, copper, iron, steel, zinc, magnesium, aluminum, or mixtures of such powders.

In another advantageous embodiment of such a composite material according to the invention, the first filler component contains a powdered metal selected from the group consisting of gold, silver, platinum, palladium, tungsten, or alloys containing such metals, or mixtures of such powders. In a further advantageous embodiment of such a composite material according to the invention, the first filler component contains a ferromagnetic metal oxide in powder form.

In a composite material according to the invention, the second filler component is advantageously selected from the group consisting of wollastonite, glass fibers, calcined gravel, calcined kaolinite, or mixtures thereof.

The thermoplastic polymer of a composite material according to the invention advantageously contains at least one polyamide and / or polyamide copolymer. Advantageously, a composite according to the invention as adhesion promoter contains a mixture of a silane with three alkoxy radicals and an alkyl radical with amino functionality and a silane with three alkoxy radicals and an alkyl radical having epoxy functionality. In such an embodiment variant, the adhesion promoter is particularly advantageously a mixture of 3-aminopropyltriethoxysilane and 3- (2,3-epoxypropoxy) propyltrimethoxysilane.

In another embodiment of a composite material according to the invention, the adhesion promoter contains maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene. Advantageously, a composite material according to the invention is pelletized. This allows easy use in conventional injection molding equipment.

Workpieces and semi-finished products according to the invention are produced from such novel composite materials.

A kit according to the invention for producing a composite material according to the invention comprises the individual components of the composite material in separate form, and / or in a mixed but not yet processed form. That is, individual compo nents ^¬ are present as unmixed powder before, or two or more of the components are premixed, are therefore present as a powder mixture or as a mixture of a powder and a liquid bonding agent. Such a kit can then, if appropriate after premixing of the components, be fed directly to a kneader in which the composite material according to the invention is then produced. In a use according to the invention, a composite material according to the invention is used for the production of workpieces by means of an injection molding process or a blow molding process.

MODE FOR CARRYING OUT THE INVENTION The examples given below serve to better illustrate the invention, but are not intended to limit the invention to the features disclosed herein.

Various variants of compositions of composites of the invention are described below, with different proportions of the components. The examples were each performed with five different metal powders with different particle morphologies (see Table 1).

Table 1

Spherical and "spattery" particle shapes result from the atomization of molten metals, the particle shape being dependent on the type of metal and the atomization conditions, while particle-shaped particles form in a ball mill when ground. Corresponding metal powders are offered, for example, by the company Carl Schlenk AG, DE 91 1 54 Roth, under the names Rogal Kupferpulver GK, Cubrotec, Rogal bronze powder GS, Rogal bronze powder GK, Rogal Messingpulver GS.

Example 1 In a first exemplary embodiment, five composite materials 1 .A, 1. B, 1 .C, 1. D, 1, E the following compositions used: 1 0 wt.% Poly ^¬ amide PA 1 2 as a polymer component, 80 wt.% Metal powder A, B, C, D, or E according to Table 1 (the letter of the respective material characterizes this metal powder used) as the first filler component, 8% by weight of wollastonite having a fiber length of about 250 μm and a fiber diameter of about 15 μm as the second filler component, and 2% by weight of an adhesion promoter component consisting of 3-aminopropyltriethoxysilane and 3- (2 , 3-epoxypropoxy) propyltrimethoxysilane in a weight ratio of 1: 1.

Table 1A

Polyamide PA 1 2 is a thermoplastic polymer of 1 2-aminododecanoic acid monomers. It has long been known and available from various manufacturers, for example from Evonik Industries AG, DE 451 28 Essen, under the type designation Vestamid® L1 670.

Wollastonite is a naturally occurring calcium silicate mineral with fibrous to sweet crystals used as a functional filler in thermoplastic polymers to improve the creep strength, stiffness and flexural strength of thermoplastic materials. Wollastonite is available from several manufacturers, for example from Fibertec Inc., Bridgewater, MA 02324, USA.

3-aminopropyltriethoxysilane (APTES, CAS No. 1 3822-56-5) is used for surface treatment of wollastonite as a filler for polyamides in order to achieve a chemical bond between the wollastonite particles and the surrounding polymer matrix, and thus a increased strength. The product is available, for example, from Jingzhou Jianghan Fine Chemical Co. Ltd., Hubei, 434005, China, under the type designation JH-A1 1 0. The density is 0.945 g / cm 3. Alternatively, other amino silanes such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-ureido-propyltriethoxysilane, N- (2-aminoethyl) - 3-aminopropylmethyldimethoxysilane and 3-aminopropylmethyldiethoxysilane also usable.

3- (2,3-Epoxypropoxy) propyltrimethoxysilane (GPTMS, 3-glycidoxypropyltrimethoxysilane, CAS No. 2530-83-8) is also used for the surface treatment of wollastonite. The product is available, for example, from Jingzhou Jianghan Fine Chemical Co. Ltd., Hubei, 434005, China, under the designation JH-01 87. The density is 1.07 g / cm 3.

The individual components of the compositions were mixed and pelletized in the usual way. Preferably, in a first step, the wollastonite is mixed with the adhesion promoter component. The resulting granules can then be processed in a conventional injection molding plant. The mentioned advantageous materials make it possible to produce components by injection molding, ie with the corresponding advantageous possibilities with regard to geometry, precision and unit costs. At the same time, the workpieces have metal-like properties, for example, in terms of specific gravity, optical appearance, electrical conductivity and thermal conductivity. Also, the feel of the material is similar to metal, since the workpieces feel cool.

The resulting workpieces achieve, despite their low polymer content, the mechanical properties of workpieces made of conventional polyamide materials. The negative influence of the high degree of filling on the mechanical strength, as it is known in the known from the prior art polymers with metallic fillers, does not occur in the aforementioned advantageous compositions of the invention composite materials.

Without wishing to be limited to a specific functional principle, it is assumed that this advantageous mechanical property of the inventive materials results from the fact that the particles of the two different filling components, in this case the metal powder and the wollastonite, are chemically crosslinked by the two adhesion promoters become. The silane end of 3-aminopropyltriethoxysilane and of 3- (2,3-epoxypropoxy) propyltrimethoxysilane bind to the silicon-containing mineral structure of the wollastonite particles. The epoxy end of 3- (2,3-epoxypropoxy) propyltrimethoxysilane binds to the surface of the metal particles, while the amino end of 3-aminopropyltriethoxysilane serves to bond to the polyamide matrix.

The mechanical strength of the resulting particle composite arises, on the one hand, from the internal strength of the wollastonite particles and the metal particles, and, on the other hand, from the mechanical interaction of the particles within the polymer. mermatrix, and finally from the binding of the two different types of particles among themselves. Spiked metal particles offer greater strength over spherical particles because of their less dense form, and higher electrical conductivity due to the increased number of points of contact between the metal particles. Due to the low volume fraction, the matrix of the polyamide has a smaller proportion of the strength, which, however, according to the invention is replaced by the binding of the wollastonite particles and metal particles among themselves by the adhesion-promoting components.

If one converts the weight proportions of the individual components (see Table 1 a) into volume fractions, with a density of polyamide 1 2 of about 1 .1 4 g / cm ³ , of wollastonite of about 2.8 g / cm ³ , Bronze of about 8.0 g / cm ³ , of brass of about 8.5 g / cm ³ , of copper of about 8.94 g / cm ³ , and the same density as polyamide for the primer mixture (the theoretical value would be 1. 0075 g / cm ³ ), which has no relevant influence at the low proportion by weight, then the following proportions in% by volume are obtained for the compositions 1 .A to 1 .E according to the above formula (I): TABLE 2

The density p _{2 of} the composition results from this

Pzus _. = ^m add _. / V _total = Σ _η m _n / Σ _η V _n = Σ _η V _n p _n / Σ _η V _n = Σ _η r _{V n} V _tota , p _n / Σ _η r _{v, n} V _total

= Σ _η r _{V n} p _n / Σ _η r _vn = Σ _η r _v _n p _n (III) The materials mentioned therefore have a density of about 4.3-4.5 g / cm ³ , which corresponds to more than half of the base metal, and about four times the polymer material.

For the mechanical properties of the materials, the specific weight of the metal as the first filling component and the wollastonite as the second filling component play no role. Various variants according to the invention can thus most easily be compared with each other ^¬ by the specific weight p, a modified ^¬ compo nent is converted to a comparison component. For example, for the compositions 1 .C to 1 .E, the weight fractions r _Meta n of brass or copper can be converted to the theoretical weight fraction r _bronze of bronze with the volume V _{metal of} the metal component remaining the same. In other words, the weight percentage is calculated as if one certain metal component together ^¬ mensetzung replaced with bronze.

Table 3

* Converted to the theoretical weight fraction of bronze (8.0 g / cm ³ ), with the same volume fraction

In the example 1 .C, therefore, the theoretical proportion by weight of the metal (brass) of r _brass = 80% by weight converted into bronze is as follows: r * _{m> brass} =

'^"M, brass (Pßronze / Plvlessing) / ('" m.Polym. ^" ^'" ^ ^ M.Messing PBronze / P essing) ^ m.Woll. ^" ^'" M.Haft = 0.79 = 79

Wt.%. The parts by weight of the other components also change, for example r * m, polym. ~~ l ^" m, Polym / (l ^" m, Polym. ^" l" m, brass (Pronron / Pwessing) l "m, wool. ~ F '^" m.Haft.) ^~ 1 0.5 GeW.%. It should be emphasized that this bronze weighted theoretical weight fraction is primarily intended to compare compositions with different metals without having to calculate the relative volume fractions, respectively, or making very different specific densities difficult to compare. Instead of polyamide PA 1 2, other polyamides such as PA 6 or PA 66 can be used as the polymer component. Polyphthalamide polymers PPA and other high performance polymers are also useful, with such embodiments, of course, providing additional benefits due to the properties of the polymer component. Other thermoplastic polymers are also usable as polymer components, such as, for example, polypropylene, polymethyl methacrylate, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyamide, polyoxymethylene, polyester, polyvinyl chloride, and thermoplastic polyurethanes, where appropriate adjustments to the adhesion promoters may be necessary. Example 2

In a further embodiment, the weight proportions of the components have been changed. The compositions according to the invention composite materials 2.A to 2.E are composed as follows: 8 wt.% Polyamide PA 1 2 as a polymer component, 85 wt.% Metal powder A, B, C, D, or E according to Table 1 as the first Fill component, 5 wt.% Wollastonite with a fiber length of about 250 μιτι and a fiber diameter of about 1 5 m as a second filling component, and 2 wt.% Of a coupling agent component consisting of 3-aminopropyltriethoxysilane and 3- (2,3-epoxypropoxy ) propyltri- methoxysilane in a weight ratio of 1: 1. This gives, converted to the volume fraction, the compositions listed in Table 4:

Table 4

This corresponds again to the compositions 1 .A to 1 .E an increase in specific gravity by about 1 0%. Converted to the density of bronze as a comparison, the values in Table 5 result.

Table 5

* Converted to the theoretical weight fraction of bronze (8.0 g / cm ³ ), for the same volume fraction Example 3

In yet another embodiment, the compositions of inventive composites 3.A to 3.E each comprise 1-3% by weight of polyamide PA.sub.12 as polymer component, 70% by weight of metal powder A, B, C, D, or E according to Table 1 as the first filling component, 1 5 wt.% wollastonite having a fiber length of about 250 μm and a fiber diameter of about 15 μm as the second filler component, and 2% by weight of an adhesion promoter component consisting of 3-aminopropyltriethoxysilane and 3- (2, 3-epoxy- propoxy) -propyltrimethoxysilane in a weight ratio of 1: 1. Table 6 below contains the compositions converted to the volume fraction:

Table 6

Corresponding to the lower metal content, the specific density of the material according to the invention also decreases. Converted to the density of bronze as a comparison, the values in Table 7.

Table 7

* Converted to the theoretical weight fraction of bronze (8.0 g / cm ³ ), with the same volume fraction In composite materials according to the invention, it is also possible to use glass fibers or calcined silica instead of wollastonite as the second filler component, or similar inorganic-mineral components. Also, wollastonite can be used with other fiber parameters, or blends of various second fill components. Examples 4, 5, 6

In further series of tests, maleic anhydride-grafted polyethylene (PEgMAH) was used as adhesion promoter. These show somewhat less good properties than the analogous compositions of Examples 1, 2 and 3, since the binding is less specific.

The composition of the novel composite materials 4.A to 4.E thus obtained are: 1.0% by weight of polyamide PA.sub.12 as polymer component, 80% by weight of metal powder A, B, C, D or E according to Table 1 as first filler component, 9 wt.% Wollastonite having a fiber length of about 250 μητι and a fiber diameter of about 1 5 μηη as a second filling component, and 1 wt.% Maleic anhydride grafted polyethylene as adhesion promoter component.

Composite materials according to the invention 5.A to 5.E turn have the following compositions: 9 wt.% Polyamide PA 1 2, 85 wt.% Metal powder A, B, C, D, or E according to Table 1, 5 wt.% Wollastonite with a Fiber length of about 250 μιη and a fiber diameter of about 1 5 μηη, and 1 wt.% Of maleic anhydride grafted polyethylene.

The compositions of inventive composites 6.A to 6.E are: 1 4 wt.% Polyamide PA 1 2, 70 wt.% Metal powder A, B, C, D, or E according to Table 1, 1 5 wt.% Wollastonite with a Fiber length of about 250 μηη and a fiber diameter of about 1 5 μιη, and 1 wt.% Of maleic anhydride-grafted polyethylene.

As an alternative to maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene may also be used as the adhesion promoter component. Composite materials according to the invention can also be used in multi-component injection molding. Thus, for example, in one step, workpieces can be produced, some of which consist of inventive composite materials, and partly of conventional thermoplastic materials. Thus, it is possible, for example, to produce a base body of a connector made of composite material 1 .A in an injection molding tool, and then to subsequently directly inject a sealing element made of a thermoplastic elastomer. Likewise, components can be produced in one operation, in which two electrically conductive domains are isolated from a material according to the invention in an insulating manner by a polymer domain injected therebetween.

Composite materials according to the invention can also be used in other production processes which were previously also reserved for thermoplastic polymers, for example various blow-molding processes such as, for example, extrusion blow molding and injection blow molding. Instead of copper or copper-based alloys, as in the aforementioned examples, other metallic or even mineral compounds can be used as the first filling components. Possible, for example, is the use of powders of steel or stainless steel (density about 7.4-8.0 g / cm ³ ), zinc (about 7. 1 g / cm ³ ), or titanium (about 4.5 g / cm ³ ) , Various metal powders can also be used as a powder mixture to combine various properties of the metals.

The use of ferromagnetic compounds as the first fillers, such as iron, cobalt or nickel, or their ferromagnetic oxides such as magnetite and hematite or ferrites, allow the production of permanent magnets with increased mechanical strength. These can be made cheaper are used as sintered or cast magnets, and have increased mechanical strength over conventional polymer matrix magnets.

Instead of comparatively heavy metals, composite materials according to the invention can also be realized with light metals or light-weight metal alloys such as, for example, aluminum (about 2.7 g / cm ³ ) or magnesium (about 1.7 g / cm ³ ). The specific gravity in this case is similar to the density of the polymer component and the Wol laston it. A composite material analogous to Embodiment 1 with 80% by weight of aluminum or magnesium as the first filler component results in an injection-moldable material according to the invention having a density of 2.3 g / cm ³ or 1.7 g / cm ³ . Such materials in combination with the injection molding process allow a cost-effective alternative to die-cast aluminum, in combination with the additional advantages of the injection molding process.

Also heavier metals can be used for composites of the invention, such as silver (about 1 0.5 g / cm ³ ), palladium (about 1 2.2 g / cm ³ ), gold (about 1 9.3 g / cm ³ ), tungsten ( about 1 9.6 g / cm ³ ), or platinum (about 2 1 .4 g / cm ³ ). Such compositions are suitable, for example, for specific applications, for example in the field of jewelry and watches, in particular for parts of watch cases, or for military technical applications.

Thus, for example, with a composition similar to Example 1 with 80 wt.% Gold a composite material according to the invention with a density of about 5.7 g / cm ³ can be realized, which is very similar to pure metallic gold, but this in terms of processability, weight and material costs is superior.

Analogous to metals and metal alloys, metal oxides can also be used as the first filling component or part of the first filling component, such as, for example, the magnetite mentioned above, or covalent carbides and metal-like carbides such as silicon carbide and tungsten carbide.

The injection-moldable composite materials according to the invention can also be used with other injection-moldable materials in a multi-component injection molding process, for example in order to produce only an outer layer or an inner core of a workpiece from the composite material.

Further examples

To investigate the mechanical strength, various compositions were prepared with copper as the metal component. For some compositions, the metal and wollastonite components were not coated with primer to obtain reference values.

Various mixtures were prepared as shown in Table 8 below. Polyamide PA6 was used as the polymer (PA Technyl 206f, density 1 .1 4 g / cm ³ , manufacturer: Rhodia Engineering Plastics, FR-691 92 Saint-Fons). For some blends, a second polymer component, namely maleic anhydride modified homo-polypropylene (Bondyram 1 001, density 0.9 g / cm ³ , manufacturer: Polyram, Ram-On Industries LP, IL-1 9205 Ram-On) was added.

The copper was coated in the form of spherical copper powder (Rogal Kupfer GK 0/80) in a spin coating process with a 50:50 wt.% Mixture of silane JH-01 87 and silane JH-A1 10. The coated copper powder was stored for three weeks, whereupon lumps formed. Subsequently, the copper was again pulverized by a ball mill ^¬. The dust formation was small, which shows only a slight abrasion of the silane. Advantageously, the copper powder can also first be coated with JH-01 87, and then with JH-A1 10.

Wollastonite was used as the inorganic / mineral filler component (Wollastonite Submicro, density 2.8 g / cm ³ , manufacturer: Kärntner Montanindustrie Ges. Mb H., AT-9400 Wolfsberg) in a fluidization coating process with silane JH-01 87 and silane J H. A 1 1 0 coated.

In a first variant, a 50:50 wt.% Mixture of the two components silane JH-01 87 and silane J H-A1 10 (average density 1 .0075 g / cm ³ ) was used. In a second variant, the silane JH-A1 10 was first added in stages, followed by the silane JH-01 87.

Table 8

The coating conditions of the various batches of copper and wollastonite used are designated by (A) - (G). (A): Without coating; (B): coated with 2.5% by weight of silanes, at 60 ° C to 30 ° C; (C): Coated with 0.5 wt% silanes, at 30 ° C; (D): 1: 1 mixture of two batches, coated with 5% by weight of silanes, at 30 ° C, or at 90 ° C; (E): Coated with 5 wt% silanes, staggered, first JH-A1 10, then JH-01 87, at 30 ° C; (F) Coated with 5% by weight silanes, staggered, first JH-A110, then JH-0187, at 60 ° C; (G) Coated with 5 wt% silanes, staggered, first JH-A110, then JH-0187, at 90 ° C.

A composition with 65 wt.% Copper batch (B) thus corresponds to 65 wt.% * 100 / (100 + 2.5) = 63.4 wt.% Copper and 65 wt.% * 2.5 / (100 + 2.5) = 1.6 wt. % Silanes as adhesion promoter. The calculations for the other batches are analog. This results in the following parts by weight in Table 9:

Table 9

* averaged density 1.08 g / cm3

According to formula (I), this results in the following volume fractions (Table 10): Table 10

Composition No. Polymer Copper wollastonite adhesion promoter

[Vol.%] [Vol.%] [Vol.%] [Vol.%]

M1 (reference mixture) 58.1 24.1 17.8 -

M2 (reference mixture) 50.0 29.7 20.3 -

M3 (reference mixture) 59.5 23.3 17.2 -

M4 54.8 22.1 16.0 7.1

M5 56.1 21.5 15.5 6.9

M6 56.8 23.5 16.5 3.2

M7 56.8 23.5 16.5 3.2

M8 56.8 23.5 16.5 3.2 The compounding of the composition was carried out on a co-rotating twin-screw extruder (standard screw with medium-high shear rate). The throughput was 1 5 kg / h, the temperature over the entire length to 230 ° C. The polymer or the two polymer components and the wollastonite were metered into the extruder together at the beginning of the screw. The copper was added with a side feed. In a later pressure-free zone, a vacuum was applied to remove gases from the material. The resulting mixed composition was pelletized.

Tensile Tests A tensile flat tensile test specimen and a strain rate of 1 mm / min were used to perform experimental tensile tests and to determine the tensile force at which the specimen broke ("breaking stress".) To prepare the flat tensile specimens, the compounded granules were held at 80 ° C for at least 3 hours These tensile bars were stored in the air for 2 days and then tested to obtain the most practical values possible.

The results are shown in FIGS. 1 and 2. The measuring accuracy is approx. 1 MPa.

FIG. 1 shows the results of the compositions with polyamide 6 as polymer component. The reference mixture M 1 shows a fracture stress of 62.9 ± 1 .9 MPa (= N / mm 2). Coating copper and wollastonite with the primer mixture (compositions M 4, M6, M7, M8) increases the fracture stress by 1 7.6% to 74 MPa, regardless of the coating parameters.

If two polymer components (compositions M3, M5) are used, ie 25% (relative) of the polyamide 6 are replaced by bondyram, the breakage decreases. Voltage, as shown in Figure 2. In the case of the reference mixture M3, the fracture stress is still 46.5 ± 0.5 MPa. Due to the surface modification of copper and wollastonite (composition M 5), the fracture stress increases by 7.5% to almost 50 MPa. The lower fracture stress values for M3 and M5 are probably due to a low compatibility of the two polymer components (polyamide is more polar than Bondyram (a modified polypropylene).

The modulus of elasticity was determined from the stress-strain diagram of the tensile tests, in the range 0.1-0.3% elongation. The modulus of elasticity of the compositions Μ Ί, M4, M6, M8 is about 7.7 GPa in each case. The E modulus of composition M2 is 9.8 GPa, which is probably due to the increased content of wollastonite and copper compared to polyamide. The E-modulus of compositions M3 and M5 is 6.6 GPa. The dispersion of the measured values is at 0.1-0.4 GPa.

Impact tests

Charpy impact tests were carried out (DIN EN ISO 1 79-1) to determine the impact strength of the compositions. The behavior of an elongated cuboid, which is notched on one side, at high deformation rate (impact load) is examined. The experiment is that a pendulum hammer with a certain kinetic energy hits the notched back of the sample and smashes it. At the time of impact with the sample, part of the kinetic energy of the hammer is absorbed by deformation processes in the sample. According to the energy that is absorbed by the sample during breaking, the pendulum hammer on the other side oscillates less high.

The pendulum had a kinetic energy of 1 1 J. The samples were worked from the parallel zone of the tensile test bars. The dimension of the impact tests was 4x1 0x80 mm. The notch was cut in the narrow side (notch A, 2 mm), the tested cross section was therefore 4x8 mm.

The experiments were each carried out with notched and not scored samples. The results are shown in FIGS. 3 and 4. As with the fracture stress, the surface treatment of the metal and wollastonite component improved the measured values. The influence is particularly great on the unnotched samples. The results are shown in FIG.

The scored samples all have a notch impact of between 6 and 6.5 kJ / m2. By surface modification an increase of the notch impact work of the uncut samples from 20.5 ± 0.2 kJ / m2 (reference mixture M 1) to 31 .4 + 1 .9 kj / m2 (mixture M7) could be achieved. This is an improvement of over 50%.

An increase in the copper content (reference mixture M2) at the expense of the PA content leads to a lower absorption of the impact energy. This is probably because there is less polymer in the mix and therefore less deformable material that can absorb the impact energy. The copper absorbs less energy because of its much higher strength than polymer.

When the two silane components were added staggered during spin-coating of the wollastonite (M6, M7, M8 blends), the resulting material was somewhat more impact-resistant compared to the addition of the two silane components in mixed form (M4 blend).

A combination of polyamide and bondyran (compositions M3 (reference), M 5) did not result in an increase in impact energy compared to the reference sample M 1. depending on a surface treatment. The corresponding results are shown in FIG.

The results suggest that the process temperature during spin coating has no effect on the final product, as the silane components were given sufficient time to chemically react during storage (resulting in lumping in the case of copper and remilling) necessary).

Bondyram had no positive influence on the strength, but in the case of the breaking stress a negative influence, which is probably due to segregation processes of the two polymer components during the extrusion. Surprisingly, the silane coupling agent component had no positive effect (impact strength at M3 and M5 is substantially equal), or less impact than pure polyamide (fracture stress).

The compositions M6-M8 show the best results, both in terms of breaking stress and impact strength. The present invention is not limited in scope to the specific embodiments described herein. Rather, those skilled in the art will recognize from the description, in addition to the examples disclosed herein, various other modifications of the present invention which are also within the scope of the claims.

Claims

claims

Composite comprising polymeric matrix component and particulate filler component, characterized in that the composite comprises:

20-60 vol.% Of a thermoplastic polymer;

- 1 5-60 vol.% Of a first particulate filler component, said first filler component is selected from the group consisting of powdered metals, metal alloys, metal oxides, covalent carbides, metal-like carbides, or mixtures of such powders;

5-30 vol.% Of a second particulate filler component, said second filler component being an inorganic and / or mineral material in powder form; and

- 1 - 1 5% by volume of a bonding agent.

2. Composite material according to claim 1, characterized in that the proportion of the thermoplastic polymer 20-50 vol.%, Preferably 33-44 vol.% Is, and / or the proportion of the first filling component 29-51 vol.% Is, and / or the proportion of the second filler component is 8-21 vol.%, and / or the proportion of the adhesion promoter is 6-9 vol.%.

3. A composite material according to claim 1 or 2, characterized in that the first filling component contains a powdered metal selected from the group consisting of bronze, brass, copper, iron, steel, zinc, magnesium, aluminum, or mixtures of such powders.

4. A composite material according to claim 1 or 2, characterized in that the first filling component contains a powdered metal selected from the group consisting of gold, silver, platinum, palladium, tungsten, or alloys containing such metals, or mixtures of such powders ,

5. A composite material according to claim 1 or 2, characterized in that the first filling component contains a ferromagnetic metal oxide in powder form.

6. The composite of claim 1, wherein the second filler component is selected from the group consisting of wollastonite, glass fibers, calcined silica, calcined kaolinite, or mixtures thereof.

7. Composite material according to one of claims 1 to 6, characterized in that the thermoplastic polymer contains at least one polyamide and / or polyamide copolymer.

8. A composite material according to any one of claims 1 to 7, characterized in that the adhesion promoter comprises a mixture of a silane having three alkoxy radicals and an alkyl radical having amino functionality and a silane having three alkoxy radicals and an alkyl radical having epoxy functionality.

9. A composite material according to claim 8, characterized in that the adhesion promoter comprises a mixture of 3-aminopropyltriethoxysilane and 3- (2,3-epoxypropoxy) propyltrimethoxysilane.

10. A composite material according to any one of claims 1 to 7, characterized in that the adhesion promoter contains maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene.

1 1. A composite material according to any one of the preceding claims, characterized in that the composite material is pelletized.

12. Workpieces and semi-finished products, made from a composite material according to one of claims 1 to 1 1.

13. A kit for producing a composite material according to any one of claims 1 to 1 1, comprising the individual components of the composite material in a separate form, and / or in a mixed but not yet processed form.

14. Use of a composite material according to any one of claims 1 to 1 1 for the production of workpieces with an injection molding process or a blow molding process.