DE3626349A1 - Moulding composition for a crosslinked foam for sound insulation applications, comprising polyolefins and ethylene-propylene rubber, and process for the production of the foam - Google Patents

Abstract

The invention relates to a foamable moulding composition and to a process for the production of elastic, partly open-celled, large-pore, partially crosslinked foams for sound insulation applications, having a mean pore size of greater than 0.6 mm, a water absorption capacity of greater than 100% by weight, based on the weight of the foam employed, and a density of less than 100 kg/m<3>, based on the mixture of polyolefins and ethylene-propylene rubber, a foaming agent and optionally a crosslinking agent, the moulding composition containing 100 parts by weight of a copolymer based on ethylene and vinyl acetate and/or a copolymer based on ethylene and acrylic acid or acrylic esters (acrylates) or acrylic acid salts, 5-50 parts by weight of a partially crystalline ethylene-propylene polymer and/or a partially crystalline ethylene-propylene terpolymer having a tear strength of greater than 5 N/mm<2>, and in particular 5-40 parts by weight of a finely divided filler, preferably chalk. <IMAGE>

Description

The invention relates to a foamable molding composition for manufacturing of elastic, partially open-celled, coarse-pored, partially cross-linked foams for sound insulation applications Based on a mixture of polyolefins and ethylene propylene Rubber, a foaming agent and optionally a crosslinking agent. The invention further relates to a method for continuous Manufacture of an elastic, partially open-cell, coarse-pored, partially cross-linked foam for sound insulation applications based on a mixture of polyolefins and ethylene Propylene rubber, a foaming agent and possibly a crosslinking agent and a use of the foam produced.  

It is known to use polyolefins with peroxides and / or high energy Network rays and simultaneously or subsequently with chemical foaming agents such. B. azodicarbonamide, sulfonyl hydrazine, Foam sulfonyl semicarbazides and the like. Here arise predominantly closed-cell foams. That applies e.g. B. for DE-AS 16 94 130 for the manufacture of chemically crosslinked polyolefin foams together with the polyolefin-miscible rubbers such as natural rubber. Ethylene Propylene rubber, butyl rubber, polyisobutylene, styrene butadiene Rubber, polybutadiene, polybutene and polyisoprene or other plastics miscible with polyolefin. The modification of cross-linked polyolefin foams by addition of rubber or other plastics serves the purpose that in particular physical properties of the added rubbers, or plastics, such as temperature resistance, better mechanical resistance, higher elasticity and tensile strength transfer to the foam. The addition of Rubbers give the polyolefin foams a higher elasticity.

Closed cell radiation cross-linked polyolefin foams are described for example in DE-OS 15 69 465, wherein these polyolefin foams by adding 5 to 500 parts by weight Parts of rubber such as natural rubber, ethylene-propylene rubber, Styrene-butadiene rubber, nitrile-butadiene rubber, polycis Butadiene rubber, neoprene rubber based on 100 parts by weight Polyethylene can be modified.

For example, it is also known, see DE-AS 28 39 733 and DE-OS 30 32 635, more temperature-resistant closed-cell crosslinked polyolefin foams based of polypropylene.

According to DE-AS 23 51 515 in a method for manufacturing fine-celled closed-cell foams made of polyolefins  through peroxidic crosslinking and foaming with a blowing agent proposed the polyolefin in addition to the peroxide and Propellant as an auxiliary another propellant with a lower temperature decomposition range than the first blowing agent add in order to reduce cell size and thus to achieve more fine-cell foam.

Methods are described in DE-AS 12 91 115 and DE-OS 22 38 366 for the production of closed-cell cross-linked foams described that under pressure, especially with a Autoclaves work. These are discontinuous Process in autoclave using pressure with which Block foams are produced. It is known that in these Process under external pressure application no propellant or propellant fission products are lost and therefore also plastics that are difficult to foam can be easily foamed, and even fine celling is achieved relatively easily can be.

According to DE-OS 23 48 468, a method for producing cross-linked Polyolefin foams with very fine and uniform closed cell structure proposed, in which the fine cell with the help of a foaming agent with a medium Particle diameter of 10 to 30 µm is to be achieved, where as the foaming agent azodicarbonamide z. B. in question is coming.

According to DE-OS 31 32 439 a method and a mixture of Polyolefins with selected rubbers suggested that a very fine-celled elastic-closed-cell foam uniform cell structure results.

The noise generated by sound vibrations can be caused by air and Structure-borne noise damping and insulation can be reduced. For the Sound absorption or sound absorption can be done by open-cell foams used successfully. For the reduction of sound energy in that some of the energy vibrates, i.e. H.  Deformation of a sound absorption material is implemented, d. H. In addition to open-cell foams, sound absorption can also be limited closed-cell soft foams like the well-known cross-linked closed cell foams based on polyolefins be used.

The invention has for its object a sound engineering both for soundproofing and for soundproofing or sound absorption suitable elastic cross-linked Foam based on polyolefins and ethylene propylene To create rubber.

It has been found according to the invention that it is possible to obtain a soundproof, partially open-cell, coarse-pore and partially crosslinked foam with an average pore size (pore diameter) of greater than 0.6 mm, in particular greater than 0.8 mm and a water absorption of at least 100% by weight on the weight of the foam used, and with a density of less than 100 kg / m ³ from a foamable molding compound based on 100 parts by weight of a copolymer based on ethylene and vinyl acetate and / or a copolymer based on ethylene and acrylic acid or acrylic acid ester or acrylic acid salts

5 to 50 parts by weight of a partially crystalline ethylene-propylene polymer and / or a partially crystalline ethylene-propylene terpolymer with a tensile strength greater than 5 N / mm ² , a Mooney viscosity (ML 1 + 4) 100 ° C greater than 50, a heat of fusion (according to DSC) of at least Δ H _s 10 J / g produced from
55-80 wt% ethylene
0-10% by weight of a ter component, in particular ethylidene norbornene or 1.4 hexadiene and
10-45 parts by weight of propylene 0 to 100 parts by weight of fillers with a particle diameter of less than 50 µm

as well as any usual amounts of additives from the series Light stabilizers, pigments, flame retardants, antistatic agents and Contains lubricant. According to the invention is selected by a Mixture of copolymers based on ethylene and ethylene Propylene rubber achieved a soundproof foam. The required coarseness of the foam is by the Interaction of several measures achieved, and based in particular on the use of very fine-grained blowing agents, very fine-grained uniform fillers and a not too high proportion of ethylene-propylene rubber.

Particularly suitable foaming agents with a higher decomposition temperature as the crosslinking agent are in particular azodicarbonamide, Dinitroso-pentamethylene-tetramine, p, p′Oxy-bis-benzenesulfonylhydrazide, Toluenesulfonyl hydrazide. Particularly suitable Coarse-pored foams are made with azodicarbonamide average particle diameter less than 10 microns reached. In contrast, coarser-grained blowing agent gives a fine-celled Foam, as can be seen for example from DE-OS 23 48 468.

The addition of fillers to the foam also leads to an enlargement of the pores, but it has been found that the fine-grained, finely divided fillers, in particular chalk (CaCO ₃ ), natural or synthetic, precipitated chalk, dolomite, talc, quartz powder, synthetic silica, heavy spar , individually or in mixtures with average particle diameters of less than 20 µm, in particular less than 10 µm, lead to a uniform, coarse pore structure with good acoustic properties. Coarse-grained fillers with larger particle diameters lead to irregular coarse-pored cell structures, which are not desirable here. It is also possible to add carbon black as a filler to improve the electrical conductivity. Furnace carbon blacks, acetylene blacks, channel carbon blacks or thermal carbon blacks can be used in particular as conductive carbon blacks. Particularly effective carbon blacks are the very good electrically conductive, non-reinforcing furnace carbon blacks, which have a particle size of less than 1 micron. These preferred types of carbon black generally have an average particle size no greater than 30 millimicron and an effective BET surface area greater than 800 m ² / g.

For the soundproof foam according to the invention, proportions of 10 to 25 parts by weight of ethylene-propylene polymer and / or ethylene-propylene terpolymer are used in the molding composition, based on 100 parts by weight of a copolymer based on ethylene, which result in an elastic Lead foam. 10 to 20 parts by weight of ethylene-propylene terpolymer and / or ethylene-propylene polymer per 100 parts by weight of copolymers based on ethylene are particularly preferably used. The partially open-cell foam according to the invention preferably has an average pore size (diameter) greater than 0.8 mm, in particular greater than 1 mm and particularly preferably greater than 2 mm. The proportion of pores with a diameter greater than 1 mm should comprise at least 50% of the foam volume in the foam according to the invention, and preferably the pores with a diameter over 2 mm should still correspond to a volume proportion of at least 30%. Ethylene-propylene copolymers or ethylene-propylene terpolymers with a tensile strength greater than 8 N / mm ² are preferably used, which have a particularly advantageous effect on the flexibility of the foam. The partial crystallinity of the selected ethylene-propylene terpolymers is measured by the DSC method in the differential scanning calorimeter using the melting curves. In the case of ethylene-propylene terpolymers, the temperature of the maximum of the melting peak TS is in the range 40-60 ° C. and the amount of heat required for melting, the so-called melting heat Δ H _S , provides information about the presence of crystalline blocks in the ethylene-propylene terpolymer. The ethylene-propylene rubbers selected according to the invention preferably have an MFI (230/5) of 0.1 to 2.0 g / 10 min. The heat of fusion Δ H _S is preferably about 10 to 50 J / g. The crosslinked foams that can be produced with the foamable molding composition according to the invention have a gel content in the range from about 50 to 90%, preferably 60 to 85%. The degree of crosslinking, ie the gel content, is measured when the crosslinked foam is extracted for 6 hours at 190 ° C. using decahydronaphthalene as the solution extractant (ASTM-D 2765-68).

The foams that can be produced with the foamable molding composition are produced with densities below 100 kg / m ^2, preferably below 70 kg / m ³ . The density is adjusted by an appropriate amount of the blowing agent. 5 to 25 parts by weight of blowing agent based on 100 parts by weight of polyolefin (copolymers of A ₁ and / or A ₂ ) are preferably used.

Those known in the manufacture of polyolefin foams applied additives, such as. B. light stabilizers, pigments, Fillers, flame retardants, mold release agents, lubricants or the like can also be the mixture for manufacturing foams can be added according to the invention.

Corresponds to the partially open-pore structure of the foam an absorbable amount of water which is at least 100% by weight based on the weight of the foam used, preferred is more than 300% by weight and particularly preferably more than 400% by weight.

A copolymer based on ethylene and vinyl acetate with a vinyl acetate content of about 3 to 30% by weight, preferably 5 to 20% by weight, and a melt index (MFI 190 / 2.16) of 1 is preferred for the foam according to the invention as polyolefin to 20, preferably 2 to 12 g / 10 min. and a density of 0.930 to 0.955 g / cm ³ used. An ethylene-butyl acrylate with a butyl acrylate content of about 10 to 30% by weight, preferably 15 to 25% by weight, an MFI (190 / 2.16) of can also be used as a copolymer based on ethylene and acrylate 1 to 5 g / 10 min. and use a density of 0.920 to 0.930 g / cm ³ .

If the foamable molding compound is not cross-linked by means of blasting is, but peroxidic, according to the invention peroxide crosslinking agent in an amount of about 0.4 up to 1.5 parts by weight based on 100 parts by weight of the used Copolymers of ethylene, which at 10 hours half-life in Benzene a decomposition temperature between 105 and 140 ° C, preferably between 110 to 130 ° C, is used. Suitable  Crosslinking agents are, for example, dicumyl peroxide or Bis (-t-butylperoxy-isopropyl) benzene.

A preferred method for the continuous production of elastic, partially open-cell, coarse-pored and partially cross-linked foams according to the invention with an average pore size of 0.6 mm and a water absorption greater than 100% by weight based on the weight of the foam used and with a density less than 100 kg / m ³ is carried out in such a way that first a homogeneous mixture of 100 parts by weight of a copolymer based on ethylene and vinyl acetate and / or ethylene and acrylic acid or acrylic acid ester or acrylic acid salts and 5 to 50 parts by weight of a partially crystalline Ethylene-propylene copolymer and / or a partially crystalline ethylene-propylene terpolymer which has a tensile strength greater than 5 N / mm ² , a Mooney viscosity (M1 1 + 4) 100 ° C greater than 50 and a heat of fusion Δ H _S according to the DSC method greater than 10 J / g, produced from 55 to 80% by weight of ethylene, 0 to 10% by weight of a ter component, in particular ethylidene norbornene or 1.4 hexadiene and 10 to 45 Ge % propylene, and a suitable foaming agent and, if appropriate, suitable crosslinking agent and 0 to 100 parts by weight. fine fillers, especially chalk, below the decomposition temperatures of the crosslinking and foaming agent, the foaming agent having a higher decomposition temperature than the crosslinking agent, is produced and shaped into a matrix and the matrix is immediately treated with high-energy jets of a dose of 1 to 20 Mrad if necessary and / or for crosslinking and foaming by means of hot air, jets and / or liquid bath to temperatures between 200 ° C and 250 ° C is heated. In addition to good mechanical properties such as tensile strength, elongation at break, compression behavior, the foam obtained by this process has good sound absorption, large porosity and high water absorption capacity at densities below 100 kg / m ³ , in particular below 60 kg / m ³ .

This is a particular advantage of the method according to the invention to see that the foam without applying external pressure or molds can be produced continuously in webs, the surfaces of the foam sheets having a compact skin form. This skin can have a thickness of at least about 5 µm. To achieve a large-pore foam is the Implementation of the method according to the invention to note that the homogeneous mixture immediately after shaping without additional Tempering or storage is crosslinked and foamed. In the case of crosslinking carried out by means of rays, the Foaming then run while peroxidic Networking this partially overlapping with the foaming can be carried out.

The matrix produced from the molding compound by extrusion is used not pre-crosslinked and not yet foamed preform referred to, which is usually extruded in tape form. These Matrix can still be calibrated to a uniform thickness to achieve what, for example, when going through one of roles formed nip takes place. The matrix is in ambient air cooled and then directly one preferably multi-stage Warming supplied to cause crosslinking and foaming. This is usually done in a heating oven with several Heating zones that merge into one another continuously or partitioned off can.

Good foaming and crosslinking of the matrix is obtained if the mixture at a temperature between 125 and maximum 160 ° C is extruded so that no premature foaming and Cross-linking can occur, and then the preform or the matrix in the first stage when going through a heater in the first zone of the same to an initial temperature of approximately between Is heated to 175 to 200 ° C to activate the crosslinking agent. Here, about 70 to 80% of the crosslinking agent Brought reaction. Then in the second stage, directly then, in the next zone of the stove, open the matrix brought an overlying temperature to crosslink  finish and initiate foaming, for example at a temperature between about 200 and 220 ° C. In the end is then in the third stage, for example in the third zone of the heater, the matrix on a turn higher brought as the temperature of the second stage lying temperature to complete the foaming, for example a temperature between about 200 and 240 ° C. The networked in this way Foam sheet based on polyolefins leaves the heating zones and is drawn off, for example, over water-cooled roller pairs and led to a winding station.

The polymers are not completely cross-linked in the foam produced, the extent or degree of networking is in the range of about 50 to 90%, preferably about 60 to 85%, is sufficient to to deliver flexible, flexible, partially open-cell foam sheets. The degree of crosslinking is expressed as a gel content in% by weight solubility determined in decalin according to ASTM-D 2765-68.

To achieve better open cell, i. H. a larger one The foam produced can still have a number of open cells mechanically reworked, especially a pressure treatment be subjected. For example, the foam by a nip formed by two rollers, which in proportion from 1: 12 to 1: 120 to the foam thickness and / or through a spiked roller with a counter-pressure roller.

In a further embodiment of the invention, it was found that a Acoustically suitable, even, large-pore foam is also obtained when the foamable molding compound foam waste on the same basis as that described above Composition and / or analog composition based on Polyolefins and / or pure polyethylene in the form of compressed Schnitzel, chips, granules or the like up to a weight percentage of 20% can be added.

For the continuous production of the foam is one good processability of the molding compound by extrusion, d. H. to Formation of a matrix, prerequisite. For the invention desired large-cell and partially open-cell foam  however, the blend of copolymers of ethylene and Ethylene propylene rubber has a relatively low MFI, which is synonymous with high viscosity - so worse Processability - but better strength of the foam is. However, this strength is for the large-pored foam necessary so that the cells or cell walls do not collapse. The flowability of the mixture is improved by adding the finely divided fillers.

For the inventive production of the sound absorbing The foamable molding materials are preferred used according to the features of claims 1 to 11.

The one produced according to the invention and surrounded by a skin on all sides Foam is with a closed surface because of its acoustic softness for sound attenuation, d. H. to Noise reduction due to deformation caused by the vibrations suitable. In a further embodiment of the invention suggested that at least on part of the surface of the continuously produced foam removes the skin becomes, so that the coarse-pored surface so exposed to Airborne sound absorption can be used. A particularly beneficial one Treatment of the continuously produced foam or foam sheet overlooks the splitting of the foam sheet their thickness before, whereby two foam sheets are created, each a compact surface in the form of a skin and a large-pored have open cell surface with sound absorption properties. The open cell surface can vary depending on the use of the Foam with a textile decorative layer, for example Fabric or fleece or the like. Are laminated. The closed one compact back can be used as a mounting surface on a carrier material serve, for example by gluing or laminating. Such a foam sheet can be used with particular advantage differently formed surfaces also by deep drawing or pressurizing using heat and pressure permanently deform, for example to trim parts for Motor vehicles such as headliners, side panels, wheel arch panels or cladding parts for machines, cabins  or the like. In particular in the deep-drawing process or vacuum forming enables a compact surface of the foam applying the vacuum and the perfect deformation of the foam to the desired structure.

The foams of the invention thus combine those for Production of molded parts required by vacuum forming good heat deformability, heat resistance and shape retention with the desired sound-insulating properties.

Foam sheets can be made with the foamable molding composition according to the invention and profiles by extrusion of a matrix with the following Networking and foaming produced economically will.

The invention is described in more detail in the examples below.

The following measurement methods were used to test properties:
MFI according to DIN 53 735
Mooney viscosity ML 1 + 4/100 according to DIN 53 523
Heat of fusion Δ H _S in the differential scanning calorimeter DSC J / g
Tear resistance N / mm ² according to DIN 53 455

For the preparation of the foam samples, the formulation components are mixed without decomposing the added organic peroxide and the added foaming agent at temperatures in the range up to about 110 ° C, e.g. B. with rollers or Banbury mixer and then extruded with an extruder to the matrix (z. B. tape 2-5 mm thick and 30-50 cm wide). The matrix is then directly z. B. through a heated by hot air from about 190 to 240 ° C channel in which it foams with crosslinking to a foam sheet with a thickness - depending on the matrix thickness and density - of about 5 to 20 mm.

Example 1:

From 100 parts by weight of ethylene vinyl acetate with a vinyl acetate content of 9%, MFI (190 / 2.16) of 7 g / 10 min, a density of 0.930 g / cm ³ ; 15 parts by weight of ethylene-propylene-diene terpolymer with an MFI (230/5) 0.7 / 10 min with a content of 67% ethylene, 30% propylene, 3% ethylidene norbornene
with a tensile strength of 15 N / mm ² ,
Mooney viscosity (ML 1 + 4) 100 ° C of 85,
a heat of fusion Δ HS of 26 J / g,
2.5 parts by weight of 40% dicumyl peroxide,
16.3 parts by weight of azodicarbonamide with an average particle size of less than 10 μm;
0.3 part by weight of Mg O;
20.0 parts by weight of CaCO ₃ with an average particle diameter of 3 μm and maximum particle diameter of 10 μm
As described above, a foam is produced and separated in the middle with a band knife with the following features:

Thickness of the foam sheet 6 mm density 39 kg / m ³ degree of crosslinking (gel content) 78% average
Pore diameter of 3-5 mm (at least 50% volume) Maximum pore diameter approx. 4 mm water absorption435%

FIG. 3 shows a photographic (negative) view of an open, that is to say undigested, side of the foam sheet produced in this way, and FIG. 4 shows an impression in natural size.

Example 2:

From 100 parts by weight of an EVA according to Example 1, 20 parts by weight an EPDM according to Example 1, 2.5 parts by weight of dicumyl peroxide 40%, 18 parts by weight of azodicarbonamide with an average Particle size less than 10 microns, 0.3 parts by weight of MgO and 5 parts by weight of chalk with a particle diameter of less than 10 µm a foam is produced, as described above, which has the following characteristics:

Thickness of the foam sheet 16.9 mm density 33 kg / m ³ Degree of crosslinking 75% Average
Pore diameter 2-3 mm (at least 50% by volume) Water absorption 430%

Example 3:

From 100 parts by weight of ethylene vinyl acetate with a vinyl acetate content of 15%, MFI (190 / 2.16) of 2.5 g / 10 min, a density of 0.94 g / cm ³ ; 15 parts by weight of ethylene-propylene-diene terpolymer according to Example 1,
2.7 parts by weight of 40% dicumyl peroxide,
16.3 parts by weight of azodicarbonamide with an average particle size of less than 10 μm
0.3 parts by weight of MgO
10.0 parts by weight of CaCO ₃ with an average particle diameter of 3 μm and maximum particle diameter of 10 μm
is produced as described above, a foam with the following features:

Thickness of the foam sheet14.7 mm density34 kg / m ³ Degree of crosslinking (gel content) 83% Average
Pore diameter of 2-3 mm (at least 30% volume) water absorption 280%

Example 4:

From 100 parts by weight of ethylene vinyl acetate according to Example 1, 20 parts by weight of an ethylene-propylene polymer with 77% ethylene, 23% propylene
with a tensile strength of 16 N / mm ² ,
Mooney viscosity (ML 1 + 4) 100 ° C of 85
a heat of fusion Δ HS of 34 J / g,
2.5 parts by weight of 40% dicumyl peroxide,
16.3 parts by weight of azodicarbonamide with an average particle size of less than 10 μm
0.3 parts by weight of MgO
40.0 parts by weight of CaCO ₃ with an average particle diameter of 3 μm and maximum particle diameter of 10 μm
is produced as described above, a foam with the following features:

Thickness of the foam sheet 12.5 mm density 47 kg / m ³ Degree of crosslinking (gel content) 70% Average
Pore diameter 2-3 mm (at least 35% by volume) Water absorption 405%

Example 5:

From a recipe according to Example 1, in which only 50 parts by weight of EVA by 50 parts by weight of ethylene butyl acrylate with a butyl acrylate content of 19%, MFI (190 / 2.16) of 2 g / 10 min and one Density of 0.925 g / cm ^{3 are} replaced, a partially cross-linked evenly large-pored foam as in Example 1 was produced.

In the drawing is foam made according to the invention exemplified.

Show it

Fig. 1 is a continuously manufactured foam sheet in cross section

Fig. 2 is a split foam sheet in cross section

FIGS. 3 and 4 photographic plan view of the open cell side of a foam sheet as a negative and positive

Fig. 5 absorption curves of the foam

Fig. 6 are enlarged photographic plan view of FIG. 4

In Fig. 1, the web 1 of a sound-crosslinked coarse-pore foam is shown schematically in cross section. The surfaces 11, 12 of the foam sheet are compact, that is to say predominantly compact and have a small thickness of approximately 0.006 mm, ie little foaming has occurred in these surface layers, since the propellant gas evaporates in these areas during the production process. Foam sheets with a thickness of 5 to about 20 mm can be produced by the method according to the invention. The core layer 13 has large pores with cells or pores 3 , namely relatively uniform large pores with an average pore size of preferably greater than 0.8 mm. This core layer is responsible for the sound-insulating, sound-absorbing and sound-absorbing properties. In order to use the foam particularly effectively, the webs 1 are split in a splitting plane 2 , which can be in the middle or off-center. A foam sheet 10 is then obtained, as shown in cross section in FIG. 2, which has a compact surface with skin 11 and an open-cell, large-pore surface 14 . This open-cell surface 14 is responsible for good sound absorption.

FIG. 3 shows the top view of the open-cell, large-pore surface of a foam photographically on a scale of 1: 1, as obtained, for example, according to Example 1.

FIG. 4 shows a stamp impression of the open-cell surface 14 of a foam web according to Example 1.

The sound absorption of the foam according to the invention was measured on the foam of Example 1 in the Apamat, specifically the sound intensity as a function of the frequency. Curve A shows the measured absorption of a cotton fleece with a basis weight of 1100 g / m ² , which has a good sound absorption capacity.

Curve B shows the absorption curve of a 6 mm thick foam sheet with a stripped surface produced according to Example 1, which has a basis weight of 180 g / m ² .

Curve C shows the absorption curve of a 12 mm thick foam sheet, composed of 2 foam sheets according to Example 1, which was needled twice and has a weight per unit area of 360 g / m ² .

A comparison of the materials shows that the foams according to curves B and C, with a considerably lower weight than the compared cotton fleece, have sufficient sound absorption for many purposes.

Fig. 6 shows a photographic image of the open foam side on a scale of 5.5: 1.

The invention enables the production of an elastic partially cross-linked Foam based on polyolefins, which for Soundproofing applications in diverse processing is suitable.

Claims (18)

1. Foamable molding compound for producing elastic, partially open-cell, coarse-pored, partially crosslinked foams for soundproofing applications with an average pore size of greater than 0.6 mm, a water absorption greater than 100% by weight based on the weight of the foam used, and a density less than 100 kg / m ³ based on a mixture of polyolefins and ethylene-propylene rubber, a foaming agent and optionally a crosslinking agent based on 100 parts by weight of a copolymer based on ethylene and vinyl acetate (A1) and / or a copolymer based on ethylene and Acrylic acid or acrylic acid ester or acrylic acid salts (A2) 5-50 parts by weight of a partially crystalline ethylene-propylene polymer (B1) and / or a partially crystalline ethylene-propylene terpolymer (B2) with a tensile strength greater than 5 N / mm ² , one Mooney viscosity (ML 1 + 4) 100 ° C greater than 50, a heat of fusion (according to DSC) of at least Δ H _S 10 J / g, made from
55-80 wt% ethylene
0-10% by weight of a ter component, in particular ethylidene norbornene or 1.4 hexadiene and
10-45% by weight of propylene 0-100 parts by weight of a filler with a particle diameter of less than 50 µm and, if appropriate, conventional amounts of additives from the series of light stabilizers, pigments, flame retardants, antistatic agents and lubricants. 2. Molding composition according to claim 1, characterized in that it contains an ethylene-propylene copolymer or ethylene-propylene terpolymer with a tensile strength greater than 8 N / mm ² . 3. Molding composition according to one of claims 1 or 2, characterized in that as a copolymer based on ethylene and vinyl acetate, an ethylene-vinyl acetate with a vinyl acetate content of about 3-30 wt .-%, a melt index MFI (190 / 2.16) of 1-20, preferably 2-12 g / 10 min. and a density of 0.930 to 0.955 g / cm ^{3 is} provided. 4. Molding composition according to one of claims 1 or 2, characterized in that as a copolymer based on ethylene and acrylate, an ethylene-butyl acrylate with a butyl acrylate content of about 10-30 wt .-% with an MFI (190 / 2.16) of about 1-5 g / 10 min and a density of about 0.920 to 0.930 g / cm ^{3 is} provided. 5. Molding composition according to one of claims 1 to 4, characterized in that for 100 parts by weight of a copolymer (A ₁ ) and / or (A ₂ ) 10 to 25 parts by weight of ethylene-propylene polymer (B ₁ ) and / or ethylene-propylene terpolymer (B ₂ ) are included. 6. Molding composition according to one of claims 1 to 5, characterized in that 5 to 40 parts by weight of chalk with a particle diameter of less than 20 µm as a filler per 100 parts by weight of copolymers (A ₁ ) and / or (A ₂ ), in particular less than 10 microns are included. 7. Molding composition according to one of claims 1 to 4, characterized in that 0.4 to 1.5 parts by weight of a peroxidic crosslinking agent are contained per 100 parts by weight of copolymers (A ₁ ) and / or (A ₂ ), which has a decomposition temperature between 105 and 140 ° C, preferably 110-130 ° C at 10 hours half-life in benzene. 8. Molding composition according to claim 7, characterized in that Dicumyl peroxide is provided as the peroxide. 9. Molding composition according to claim 7, characterized in that bis (-t-butylperoxy-isopropyl) benzene is provided as the peroxide is. 10. Molding composition according to one of claims 1 to 9, characterized in that a foaming agent with a higher decomposition temperature than that Crosslinking agent is provided, in particular azodicarbonamide, Dinitroso-pentamethylenetetramine, p, p′Oxy-bis-benzenesulfonylhydrazide, Toluenesulfonyl hydrazide. 11. Molding composition according to claim 10, characterized in that as a foaming agent an azodicarbonamide with an average Particle diameter smaller than 10 microns is provided. 12. A process for the continuous production of an elastic, partially open-cell, large-pore, partially crosslinked foam for soundproofing applications based on a mixture of polyolefins and ethylene-propylene rubber, a foaming agent and optionally a crosslinking agent, characterized in that initially a homogeneous mixture of 100 wt . Parts of a copolymer based on ethylene and vinyl acetate and / or ethylene and acrylic acid or acrylic acid ester or acrylic acid salts and 5-50 parts by weight of a partially crystalline ethylene-propylene copolymer and / or a partially crystalline ethylene-propylene terpolymer, the one Tensile strength greater than 5 N / mm ² , a Mooney viscosity (ML 1 + 4) 100 ° C greater than 50 and a heat of fusion Δ H _S according to the DSC method greater than 10 J / g, made from 55-80% by weight ethylene, 0-10% by weight of a ter component, in particular ethylidene norbornene or 1.4 hexadiene and 10-45% by weight of propylene, and a suitable foaming agent and, if appropriate, suitable crosslinking agent tel and 0-100 parts by weight of a finely divided filler below the decomposition temperatures of crosslinking and foaming agents, the foaming agent having a higher decomposition temperature than the crosslinking agent, is produced and formed into a matrix and the matrix immediately, possibly with high-energy rays Dose of 1-20 Mrad treated and / or for crosslinking and foaming by means of hot air, jets and / or liquid bath to temperatures between 200 ° C and 250 ° C and a foam with an average pore diameter of greater than 0.6 mm and one Water absorption greater than 100 wt .-% based on the weight of the foam used and a density less than 100 kg / m ^{3 is} obtained, the surface of which is digested. 13. The method according to claim 12, characterized in that to reach a larger number of open cells of the Foam is mechanically reworked, especially one Is subjected to pressure treatment.   14. The method according to claim 13, characterized in that the foam through a gap formed by two rollers, which is in a ratio of 1 to 12 to 1 to 120 to the foam thickness, and / or guided over a spiked roller with a counter-pressure roller becomes. 15. The method according to any one of claims 12 to 14, characterized in that at least on part of the surface of the manufactured Foam is removed from the skin. 16. The method according to any one of claims 12 to 15, characterized in that the foam produced is split. 17. The method according to any one of claims 12 to 16, characterized in that the foamable molding compound compacted foam waste in the form of chips, chips, granules or the like, from a foam based on analog compositions and / or polyethylene foam up to a proportion of about 20 wt .-% are added. 18. Use of a molding compound according to one of claims 1 to 11 or by the method of claims 12 to 17 manufactured foam for the production of sound absorbing molded parts by deep drawing especially for motor vehicles, machines or the like, if necessary on an open-cell foam side with a textile decorative layer are laminated.