DE102005042942A1 - Expandable polyolefin particle or expanded polyolefin foam particle, useful for producing shaped parts that are useful as e.g. shock proof packing materials, comprises polyolefin and organic or inorganic fillers (e.g. talc and chalk) - Google Patents

Abstract

Expandable polyolefin particle or expanded polyolefin foam particle comprises polyolefin and organic or inorganic fillers (5-80 wt.%). Independent claims are included for: (1) shaped parts with a density of 8-600 g/l, obtained by fusing the polyolefin foam particle with hot-air or water vapor; (2) preparation of the expandable polyolefin particles; and (3) preparation of the expanded polyolefin foam particles.

Description

The The present invention relates to expandable polyolefin particles and expanded polyolefin foam particles containing from 5 to 80% by weight of organic or inorganic fillers contain.

expanded Polypropylene (EPP) particles are used on an industrial scale Production of foam moldings used. These will mainly as elastic, shockproof Packaging materials used, in addition, also heat-insulating properties to have.

to further reduction of thermal conductivity can Infrared radiation reflecting metal pigments such as aluminum powder (EP-A 0 790 273) or graphite particles (WO 00/37546) in the EPP particles be incorporated. The resulting foam molded parts be for example for Applications used in the automotive industry.

From Polyolefins are known to crystallize from numerous Pigments (Industrial Organic Pigments, Autumn / Hunger, 2nd ed. 1995, S. 75), which leads to the deterioration of important application technology Properties such as warping, tensions or shrinkage anomalies to lead can.

by virtue of of high price or influencing the crystallization of Polyolefins are not all pigments unrestricted Fillers from Polyolefin foams suitable.

The not prepublished PCT / EP / 04/013748 describes particle foam moldings made of expandable, filler containing polymer granules, in particular expandable polystyrene, by welding of prefoamed foam particles.

task The object of the present invention was to remedy the disadvantages mentioned and expandable polyolefin particles and expanded polyolefin foam particles, In particular polypropylene foam particles (EPP) to find that inexpensive polyolefin particle foams with good mechanical properties Properties, foam structure and low thermal conductivity are processed can.

Accordingly, were expandable polyolefin particles or expanded polyolefin foam particles, which contains from 5 to 80% by weight of organic or inorganic fillers contain.

Surprisingly, despite the presence of fillers, the polyolefin particle foams according to the invention exhibit a high degree of closed-cell quality, with more than 60%, preferably more than 70, particularly preferably more than 80% of the cells of the individual foam particles being closed-celled as a rule. The cell number is preferably 5-500 cells per mm ² .

Suitable fillers are organic and inorganic powders or fibrous materials, as well as mixtures thereof. As organic fillers z. As wood flour, starch, flax, hemp, ramie, jute, sisal-cotton cellulose or aramid fibers are used. As inorganic fillers z. As silicates, barite, glass beads, zeolites or metal oxides are used. Preference is given to pulverulent inorganic substances, such as talc, chalk, kaolin (Al ₂ (Si ₂ O ₅ ) (OH) ₄ ), aluminum hydroxide, magnesium hydroxide, aluminum nitrite, aluminum silicate, barium sulfate, calcium carbonate, calcium sulfate, silica, quartz powder, Aerosil, alumina, mica or wollastonite or spherical or fibrous inorganic materials such as glass beads, glass fibers or carbon fibers. The mean particle diameter or, in the case of fibrous fillers, the length should be in the range of the cell size or smaller. An average particle diameter in the range from 0.1 to 100 μm, preferably in the range from 1 to 50 μm, is preferred.

By the type and amount of fillers can the properties of the expandable thermoplastic polymers and the particle foam moldings obtainable therefrom influence. The proportion of the filler is usually in the range of 5 to 80, preferably 10 to 40 Wt .-%, based on the thermoplastic polymer. At filler contents in the range of 5 to 30 wt .-%, no significant deterioration the mechanical properties of the particle foams, such as flexural strength or compressive strength observed. Through the use of adhesion promoters, such as maleic anhydride-modified Polyolefins, polymers or organosilanes containing epoxide groups the connection of the filler to the polymer matrix and thus the mechanical properties of the Particle foam moldings are significantly improved.

In In general, inorganic fillers reduce flammability. In particular, by the addition of inorganic powders, such as aluminum hydroxide the fire behavior can be significantly improved.

at Use of magnetic fillers, z. B. magnetic metal oxides, in particular magnetic iron oxides, can Polyolefin particle foams for shielding purposes.

The expandable Po inventive Lyolefin particles and expanded polyolefin foam particles have a crystal structure that is detectable by differential scanning calorimetry (DSC) thermogram through a low temperature melt peak and a high temperature peak. The amount of heat of the high-temperature peak, measured at a heating rate of 10 ° C / min, is preferably 2 to 40 J / g, more preferably 3 to 30 J / g. It is determined via the peak area as described in EP-A 0 963 827.

The expanded according to the invention Polyolefin particles can be in principle by suspension or Extrusion process directly or indirectly via expandable polyolefin particles and foaming in a Druckvorschäumer with steam or hot air produce.

At the Suspension process, the polyolefin as a filler-containing Granules with water, a suspension aid and the propellant in a closed reactor to above the softening temperature of the granules heated. The polymer particles with the Impregnated blowing agent. Subsequently You can either use the hot suspension cooling down, wherein the particles solidify to include the propellant and relax the reactor. The blowing agent-containing obtained in this way (Expandable) particles are heated by heating to the expanded particles foamed, see, e.g. WO 01/29119 and EP-A 1 281 729. Alternatively, the name is Suspension without cooling abruptly relax (explosion expansion method), the Soften, blowing agent-containing particles directly to the expanded Foaming particles, see, e.g. EP-A 53 333 and 611 795.

At the Extrusion process is the polyolefin in an extruder under Melting with filler and a blowing agent, which is supplied to the extruder. The propellant-containing mixture is used either under such pressure and temperature conditions are squeezed out and granulated that the polyolefin granules does not foam (expanded) using, for example, an underwater pelletizer which is operated at a water pressure of more than 2 bar, see EP-A 1 132 420. Obtained propellant-containing, expandable particles, which by subsequent heating to the expanded particles are foamed. Alternatively you can the mixture also without overpressure squeeze and granulate. The melt strand foams up and you get by granulation the expanded particles, see EP-A 588 321 and DE-A 197 56 264.

• a) Homopolypropylen,
• b) Randomcopolymere des Propylens mit 0,1 bis 15, bevorzugt 0,5 bis 12 Gew.-% eines Comonomeren. Bevorzugtes Comonomer ist Ethylen oder ein C_4-10-α-Olefin oder deren Mischungen. Besonders bevorzugte Randomcopolymere sind Copolymere von Propylen mit 0,5 bis 6 Gew.-% Ethylen oder mit 0,5 bis 15 Gew.-% But-1-en, oder ein Terpolymer aus Propylen, 0,5 bis 6 Gew.-% Ethylen und 0,5 bis 6 Gew.-% But-1-en,
• c) Mischungen der unter a) oder b) genannten Polymere mit 0,1 bis 75, bevorzugt 3 bis 50 Gew.-% eines Polyolefin-Elastomeren, z.B. eines Ethylen-Propylen-Blockcopolymeren mit 30 bis 70 Gew.-% Propylen,
• d) Polyethylene, beispielsweise LD (low density), LLD (linear low density), MD (medium density) oder HD (high density), HMW (high molecular weight) oder UHMW (ultra high molecular weight), oder
• e) Mischungen der unter a) bis d) genannten Polymere, wobei ggf. Phasenvermittler mitverwendet werden, um die Phasenanbindung der in manchen Fällen unverträglichen Polymere zu verbessern.

Suitable polyolefins are in particular suitable:

• a) homopolypropylene,
• b) Randomcopolymers of propylene with 0.1 to 15, preferably 0.5 to 12 wt .-% of a comonomer. Preferred comonomer is ethylene or a C _4-10 α-olefin or mixtures thereof. Particularly preferred random copolymers are copolymers of propylene with 0.5 to 6 wt .-% of ethylene or with 0.5 to 15 wt .-% but-1-ene, or a terpolymer of propylene, 0.5 to 6 wt .-% Ethylene and 0.5 to 6% by weight of but-1-ene,
• c) mixtures of the polymers mentioned under a) or b) with from 0.1 to 75, preferably from 3 to 50,% by weight of a polyolefin elastomer, for example an ethylene-propylene block copolymer having from 30 to 70% by weight of propylene,
• d) polyethylenes, for example LD (low density), LLD (linear low density), MD (medium density) or HD (high density), HMW (high molecular weight) or UHMW (ultra high molecular weight), or
• e) mixtures of the polymers mentioned under a) to d), optionally using phase promoters, in order to improve the phase connection of the polymers, which are incompatible in some cases.

Of the Crystallite melting point of suitable polyolefins is usually in the range of 90 to 170 ° C. It is for example the peak maximum in differential scanning calorimetry (DSC) diagram determinable. The heat of fusion of the polyolefins is also determinable and amounts by DSC generally 20 to 300 J / g. The melt flow index (MFI, melt flow index) of the polyolefin is usually 0.1 to 100 g / 10 min, determined at 230 ° C and 2.16 kg load for Propylene polymers or 190 ° C. and 2.16 kg load for Ethylene polymers, according to DIN 53 735.

The polyolefin used is preferably a polypropylene. Preferred polyolefins are homo- or copolymers of propylene with 0.1 to 15 wt .-% of ethylene and / or 1-butene, particularly preferably propylene-ethylene copolymers with 1 to 5 wt .-% of ethylene. They have a crystallite melting point of 130 to 160 ° C, and a density of about 0.9 g / cm ³ , on.

The Polyolefins are known and can after all usual Be obtained, for example, after the high pressure (ICI), Medium pressure (Phillips), low pressure (Ziegler), gas phase, gas phase fluidized bed or metallocene method.

The polyolefin can be blended with up to 50% of its weight of another thermoplastic having a glass transition temperature (determined, for example, as a point of inflection in the DSC diagram) below 180 ° C. Suitable thermoplastics are, for example, polyamides in amounts of from 5 to 40% by weight, the mixture comprising customary phase promoters, for example block copolymers, such as Exxelor P 1015 (Ex xon) can be added.

It It has been found that the invention also without admixing such other thermoplastics feasible is. This is preferred insofar as by a foreign thermoplastic the recyclability of the polyolefin or of the foam produced therefrom suffers. Rubbery ethylene-propylene copolymers which are used for Elastication can be added, do not count in this sense to the other thermoplastics.

The Polyolefin can be used as commercial granules, Powder, semolina or be used in any other form. Conveniently, a granulate is used. It is suitable, e.g. a so-called Minigranulat with a preferred middle Diameter of 0.2 to 10, in particular from 0.5 to 5 mm. This mostly cylindrical or round mini granulate is made by extruding the polyolefin together with fillers and / or the thermoplastic to be mixed, and further additives, Squeezing out of the extruder, optionally cooling and granulating. For cylindrical minigranules is the length preferably 0.2 to 10, in particular 0.5 to 5 mm. The granules can also platelet-shaped be.

The expandable according to the invention Polyolefin particles can after the suspension process or after the extrusion process getting produced.

For example you can in the suspension process, the fillers in the production of the polyolefin minigranule, i. the minigranule already contains the filler. Likewise preferred in the extrusion process, the fillers in the extruder, in which the blowing agent is mixed, metering. The fillers can as such, or e.g. mixed with customary dispersing aids, or mixed with a small proportion of polymers as a so-called masterbatch, added become.

ever according to the method used the preferred propellants may vary. In the suspension process is used as the blowing agent preferably organic liquids or inorganic gases or mixtures thereof. As liquids come halogenated hydrocarbons in question, are preferred but saturated, aliphatic hydrocarbons, in particular those having 3 to 8 C-atoms. Particularly preferred is n-butane. Suitable inorganic Gases are nitrogen, air, ammonia or carbon dioxide.

In the preparation via extrusion process is preferably used as the blowing agent volatile organic compounds having a boiling point at atmospheric pressure 1013 mbar from -25 to 150, especially -10 to 125 ° C. Well suited are hydrocarbons (preferably halogen-free), in particular C _4-10 -alkanes, for example the isomers of butane, pentane, hexane, heptane and octane, particularly preferably s-pentane. Suitable blowing agents are also sterically more demanding compounds such as alcohols, ketones, esters, ethers and organic carbonates. Preferred ketones are 3,3-dimethyl-2-butanone (= pinacolone or obsolete pinacolone) and 4-methyl-2-pentanone (= methyl isobutyl ketone). As the ester, it is preferable to use isobutyl acetate.

Also Halogenated hydrocarbons can be used However, the blowing agent is preferably halogen-free. low Proportions of halogen-containing blowing agent in the blowing agent mixture should but not excluded. It is understood that also mixtures said blowing agent can be used.

The Amount of blowing agent is preferably 0.1 to 40, in particular 0.5 to 35 and particularly preferred 1 to 30 parts by weight, based on 100 parts by weight of polyolefin used.

The expanded according to the invention Polyolefin can also the usual Contain additives. Such additives are e.g. Antioxidants, stabilizers, Flame retardants, waxes and dyes. You will be in usual, used in known amounts.

At the Suspension process is usually worked batchwise in one Impregnating container, e.g. in a stirred tank reactor. The reactor is charged with the polyolefin, e.g. as a filler-containing minigranulate, dosed, as well Water or other suspension medium, and the blowing agent and optionally a suspension aid. As suspension aids are water-insoluble inorganic stabilizers, such as tricalcium phosphate, magnesium pyrophosphate, metal carbonates; also polyvinyl alcohol and surfactants such as sodium dodecylarylsulfonate. They usually become in amounts of 0.05 to 10 wt .-%, based on the polyolefin used.

After that The reactor is closed and the reactor contents to an impregnation temperature from usually at least 100 ° C heated. The propellant can before, during or after heating added to the reactor contents become. The impregnation temperature should be near the softening temperature of the polyolefin are. For polypropylene are impregnating temperatures from 110 to 180, in particular 130 to 160 ° C preferred.

Depending on the amount and type of blowing agent and on the level of the temperature, a pressure (impregnation pressure) arises in the sealed reactor which is generally from 2 to 100 bar (absolute). If necessary, one can regulate the pressure by a pressure regulating valve or by repressing blowing agent. At the impregnation conditions, elevated temperature and overpressure diffuse blowing agent into the polymer granules particles. The impregnation time is generally 0.5 to 10 hours.

In an embodiment of the suspension process becomes the heated suspension after impregnation on usually below 100 ° C cooled, whereby the polyolefin re-solidifies and the blowing agent includes. After that, relax. You get expandable polyolefin particles, which finally separated in the usual way from the Sus pension become. Adhering water is usually obtained by drying, e.g. in the current dryer, removed. If necessary, you can do it before or then remove adhering suspension aid by passing the Particles treated with a suitable reagent. For example you can with an acid like Nitric acid, hydrochloric acid or treat sulfuric acid, acid soluble suspending agents, e.g. Metal carbonates or tricalcium phosphate.

The obtained expandable polyolefin particles are then by Heat foamed to the expanded polyolefin particles, as described below becomes.

In another embodiment the suspension process, also explosion expansion method or Dokan method (see EP-A 611 795), the heated Suspension not cooled, but hot without cooling down suddenly relaxed. When relaxing, this first expands into the polyolefin particles diffused blowing agent "explosive" and foams the soften particles. You get expanded polyolefin particles.

Usually the suspension is passed through a nozzle, a valve or other suitable device relaxes. you the suspension can be directly at atmospheric pressure, for example 1013 mbar, relax. Preferably, however, is relaxed in an intermediate container, its pressure for foaming the polyolefin particle is sufficient, but above atmospheric pressure can lie. Suitably, one relaxes to a pressure of e.g. 0.5 to 5, in particular 1 to 3 bar (absolute). While relaxing can you in the impregnation tank the impregnation keep constant by repressing propellant. Usually one cools After suspension, the suspension separates the expanded polyolefin particles in usual Remove from the suspension, if necessary, before or after adhering removed Suspension auxiliary as already described, and washes and finally dries the particles.

At the Extrusion processes, the polyolefin, the blowing agent, the fillers and optionally nucleating agents, and additives together (as Mixture) or separately, at one or at different Supplied positions of the extruder. It is possible however, not required, advance from the solid components one Mixture produce. For example, one can first polyolefin, fillers, Nucleating agent and possibly additives mix and mix the Feed extruder, after which the propellant is fed to the extruder, i. the extruder mixes the blowing agent in a polymer melt. Likewise the extruder is a mixture of blowing agents and fillers respectively, i.e. the fillers first add with the propellant.

in the Extruders are the starting materials mentioned under melting of the Polyolefins mixed. Extruders are all common screw machines into consideration, in particular single-screw and twin-screw extruder (for example type ZSK from Werner & Pfleiderer), Ko-kneaders, Kombiplast machines, MPC kneading mixers, FCM mixers, KEX kneading screw extruders and shear roller extruders as e.g. in Saechtling (ed.), plastic paperback, 27. Edition, Hanser-Verlag Munich 1998, chap. 3.2.1 and 3.2.4 are described. The extruder is usually operated at a temperature at which the polyolefin melt is present, for example at 130 to 250, in particular 160 to 220 ° C.

Rotation speed, Length, Diameter and configuration of the extruder screw (s), quantities supplied and extruder throughput are chosen in a known manner such that in the extruded polyolefin fillers Nucleating agent and possibly the additives evenly distributed are.

In an embodiment The extrusion process produces expandable particles. To prevent the blowing agent-containing melt already at Outlet from the extruder foams, becomes the melt strand at such temperature and pressure conditions pressed out and granulated that practically no foaming (expanding) he follows. These conditions can on the type and amount of polymers, additives and in particular be different from the propellant. Leave the optimal conditions easily determined by preliminary tests.

A technically favorable method is the underwater granulation in a water bath, which has a temperature below 100 ° C and is under a pressure of at least 2 bar (absolute). The temperature must not be too low, otherwise the melt solidifies on the nozzle plate, and it must not be too high, otherwise the melt expands. The higher the boiling point of the propellant and the lower the propellant the higher the water temperature and the lower the water pressure can be. In the particularly preferred propellant s-pentane, the optimum water bath temperature is 30 to 60 ° C and the optimum water pressure at 8 to 12 bar (absolute). Instead of water you can also use other suitable cooling media. Likewise one can apply a water ring granulation. In this case, the cutting space is encapsulated in such a way that the granulating device can be operated under pressure.

you receives in this way expandable polyolefin particles, which are subsequently from Separate water and dried if necessary. After that they will foamed to expand polyolefin particles as described below.

In another embodiment of the extrusion process, the blowing agent-containing melt without Underwater granulation, water ring granulation or other precautions, the one foaming prevent, squeeze and granulate. For example, you can squeeze directly into the atmosphere. It foams the extruded melt strand, and by granulating the foamed strand receives one expanded polyolefin particles.

• a) Aufschmelzen von Polyolefin mit 5 bis 80 Gew.-% Füllstoffe und Extrusion zu Minigranulat mit einem mittleren Durchmesser von 0,2 bis 10 mm,
• b) Imprägnieren des Minigranulates mit 0,1 bis 40 Gew.-% eines flüchtigen Treibmittels in wässriger Suspension unter Druck bei Temperaturen im Bereich von 100 bis 170°C und Abkühlen der Suspension auf 20 bis 95°C,
• c) anschließendem Entspannen.

Preferred processes for preparing expandable polyolefin particles include the steps:

• a) melting of polyolefin with 5 to 80 wt .-% fillers and extrusion to minigranules having an average diameter of 0.2 to 10 mm,
• b) impregnating the minigranules with 0.1 to 40% by weight of a volatile blowing agent in aqueous suspension under pressure at temperatures in the range from 100 to 170 ° C. and cooling the suspension to 20 to 95 ° C.,
• c) then relaxing.

• a) Aufschmelzen von Polyolefin mit 5 bis 80 Gew.-% Füllstoffe und Extrusion zu Minigranulat mit einem mittleren Durchmesser von 0,2 bis 10 mm,
• b) Imprägnieren des Minigranulates mit 0,1 bis 40 Gew.-% eines flüchtigen Treibmittels in wässriger Suspension unter Druck bei Temperaturen im Bereich von 100 bis 170°C und
• c) anschließendem Entspannen.

A preferred process for preparing expanded polyolefin foam (EPP) particles comprises the steps

• a) melting of polyolefin with 5 to 80 wt .-% fillers and extrusion to minigranules having an average diameter of 0.2 to 10 mm,
• b) impregnating the minigranules with 0.1 to 40 wt .-% of a volatile blowing agent in aqueous suspension under pressure at temperatures in the range of 100 to 170 ° C and
• c) then relaxing.

Provided you get expandable particles are foamed in a manner known per se (foamed), wherein the expanded according to the invention Polyolefin particles arise. The foaming is usually done by Heating the expandable particles in conventional Verschäumungsvorrichtungen, e.g. with hot air or overheated Water vapor in a so-called Druckvorschäumer, as he for processing of expandable polystyrene (EPS) is common. Preferably one foams the particles at a temperature at which they soften (softening range), e.g. at temperatures of 100 to 180 ° C.

One foams one with water vapor, so is depending on the type and amount of polyolefin and blowing agent, and the desired Density of the foam to be produced, the pressure of the water vapor usually 2 to 8, preferably 1 to 5 bar (absolute). This results in higher pressures lower densities of the foamed Polyolefins, i. With the water vapor pressure you can get the desired density to adjust. The duration of foaming is usually 1 to 300, preferably 1 to 30 sec. After foaming is relaxed and cooled. Prefers is the expansion factor during foaming 2 to 50.

The polyolefin particles can be provided with an antiblocking agent before and / or after foaming. Suitable antiblocking agents are talc, metal compounds such as tricalcium phosphate, calcium carbonate, silicas, especially fumed silicas such as Aerosil ^® from Messrs. Degussa, salts of long chain (eg C _10-22) carboxylic acids, for example stearic acid such as calcium stearate, esters of long chain carboxylic acids, for example Glycerinester as the glycerol stearates , and silicone oils. The antiblocking agent is typically applied to the particles by mixing, spraying, tumbling or other conventional methods. It is usually used in amounts of 0.01 to 20, preferably 0.1 to 10, particularly preferably 0.5 to 6 parts by weight, based on 100 parts by weight of the polyolefin.

you receives In any case, polyolefin particles expanded at a density. Preferred densities are from 5 to 600 g / l, and more preferred 10 to 300 g / l.

The expanded particles are usually at least approximately spherical and usually a diameter of 0.2 to 20, preferably 0.5 to 15 and in particular 1 to 12 mm. For non-spherical, e.g. elongated or cylindrical Particles, by diameter is meant the longest dimension.

Foams can be produced from the polyolefin particles according to the invention, for example by welding them together in a closed mold under the action of heat. For this purpose, the particles are filled into the mold and, after closing the mold, initiates steam or hot air, whereby the particles continue to expand and co-exist other to the foam, preferably with a density in the range of 8 to 600 g / l, welding. The foams can be semi-finished products, such as plates, profiles or webs, or finished moldings with simple or complicated geometry. Accordingly, the term includes polyolefin foam, foam semi-finished products and foam moldings.

object The invention therefore also relates to the use of the expanded polyolefin particles for the production of polyolefin foams, as well as polyolefin foams, available from the expanded polyolefin particles.

example 1

75 Parts by weight of a propylene-ethylene random copolymer (2% by weight) Ethylene) together with 25 parts by weight of calcium carbonate in one Extruder at about 220 ° C mixed. The mixture became pellets by underwater granulation granulated by about 1.2 mg.

These Granules were impregnated as follows.

In a closed stirred tank were stirred 100 kg of the propylene-ethylene random copolymer granules, and 6.7 kg of tricalcium phosphate in 245 kg of water at room temperature dispersed. After addition of 24 kg of n-butane, the reactor contents became to about 130 ° C heated whereby a pressure of approx. 20 bar arose. Thereafter, the reactor contents became through a nozzle in an intermediate container relaxed. The resulting expanded polypropylene particles were separated, washed and then dried. Bulk density the expanded particle was 26.4 g / l. The amount of heat of the high temperature peak from the DSC thermogram at a heating rate of 10 ° C / min was 19.2 J / g.

The Foam particles were placed in a closed mold and with Water vapor under pressure to form parts with a density of 60 g / l welded.

The thermal conductivity according to DIN 52612 was 38 mW / (m · K).

Comparative test

example 1 was mixed with 100 kg of propylene-ethylene random copolymer granules no calcium carbonate was contained repeatedly. From the obtained foam particles with bulk density 27.4 g / l, molded parts having a density of 60 g / l were produced. The thermal conductivity according to DIN 52612 was 42 mW / (m · K). The heat the high temperature peak from the DSC thermogram at a heating rate of 10 ° C / min was 23.4 J / g.

Example 2

27.7 Parts by weight of a propylene-ethylene random copolymer (2% by weight) Ethylene) together with 72 parts by weight of iron oxide in an extruder at about 220 ° C mixed. The mixture was forced through a die and the resulting strands into pellets granulated.

This Granules were impregnated as follows.

In a closed stirred tank were stirred 10 kg of the propylene-ethylene random copolymer granules, and 0.3 kg of tricalcium phosphate in 60 kg of water at room temperature dispersed. After adding 2 kg of n-butane, the reactor contents became to about 135 ° C heated whereby a pressure of approx. 18 bar arose. Thereafter, the reactor contents became through a nozzle in an intermediate container relaxed. The obtained NEN expanded polypropylene particles were separated, washed and then dried. Bulk density the expanded particle was 110 g / l.

Claims (11)

Expandable polyolefin particles or expanded polyolefin foam particles, characterized in that they contain 5 to 80 wt .-% organic or inorganic fillers. Expandable polyolefin particles or expanded Polyolefin foam particles, according to claim 1, characterized in that they as filler powdery inorganic substances, such as talc, chalk, kaolin, aluminum hydroxide, Magnesium hydroxide, aluminum nitrite, aluminum silicate, barium sulfate, Calcium carbonate, calcium sulfate, silica, quartz powder, aerosil, alumina, Mica, glass beads, glass fibers, carbon fibers, wollastonite or iron oxide contain. Expandable polyolefin particles or expanded Polyolefin foam particles according to Claim 1 or 2, characterized that the fillers a average particle diameter of 0.1 to 100 microns have. Expandable polyolefin particles or expanded polyolefin foam particles according to any one of claims 1 to 3, characterized in that the polyolefin is a homopolypropylene or a random copolymer of propylene with 0.1 to 15 wt .-% of ethylene and / or C ₄ -C ₁₀ α-olefin is. Expandable polyolefin particles or expanded polyolefin foam particles according to claim 4, characterized by having a low temperature melt peak and a high temperature melt peak in the differential scanning calorimetry (DSC) thermogram. Expandable polyolefin particles or expanded Polyolefin foam particles according to claim 5, characterized in that that the amount of heat of the High temperature peaks, measured at a heating rate of 10 ° C / min, 2 is up to 40 J / g. Expanded polyolefin foam particles according to one of claims 1 to 6, characterized in that they have a density in the range from 5 to 600 g / l. Moldings with a density in the range of 8 to 600 g / l, available by welding of polyolefin foam particles according to any one of claims 1 to 7 with hot air or water vapor. Process for the preparation of expandable polyolefin particles according to claims 1 to 6, comprising the steps a) melting of polyolefin with 5 to 80 wt .-% filler and extruding into minigranules having a mean diameter of 0.2 to 10 mm, b) impregnate of minigranules with 0.1 to 40 wt .-% of a volatile Propellant in aqueous suspension under pressure at temperatures in the range of 100 to 170 ° C and cooling the Suspension at 20 to 95 ° C, c) followed by Relax. Process for producing expanded polyolefin foam particles (EPP) according to claims 1 to 7, comprising the steps d) melting of polyolefin with 5 to 80 wt .-% filler and extruding into minigranules having a mean diameter of 0.2 to 10 mm, e) impregnating of minigranules with 0.1 to 40 wt .-% of a volatile Propellant in aqueous suspension under pressure at temperatures in the range of 100 to 170 ° C and f) followed by Relax. Process for producing expanded polyolefin foam particles (EPP), characterized in that expandable polyolefin foam particles according to the method according to claim 9 and pre-foams in a Druckvorschäumer with steam or hot air.