DE3626350A1 - Interior lining for a motor vehicle and process for the production thereof - Google Patents

Abstract

The invention relates to an interior lining for a motor vehicle, comprising a foam panel which is permanently deformed under the application of heat and pressure to form the desired three-dimensional configuration and consists of a crosslinked polyolefin foam which has a weight per unit volume of less 100 kg/m<3> with a laminated-on decorative layer, the foam panel consisting of a sound-absorbent, flexible, partly open-celled, coarse-pored, partly cross-linked foam with an average pore size of greater than 0.6 mm, a water absorption greater than 200 % by weight based on the weight of the foam used, based on a mixture of polyolefins and ethylene-propylene rubber, a foaming agent and, if appropriate, a crosslinking agent and one panel side has a virtually impermeable skin of non-foamed mixture and the opposite panel side is designed coarse-celled and open, and a process for producing the interior lining. <IMAGE>

Description

The invention relates to an interior trim for a motor vehicle, from a foam sheet permanently deformed using heat and pressure to the desired three-dimensional configuration, from a crosslinked polyolefin foam which has a density of less than 100 kg / m ³ , with a laminated decorative layer and a method for their manufacture.

Such interior panels are for example from the EP-A 00 46 839 known. They consist of a closed cell foamed crosslinked polypropylene containing 10-25% by weight of polyethylene. The sound absorbing properties closed cell foams, however, are in many cases not sufficient because closed-cell soft foams do have a sound-absorbing effect, but only slightly sound-absorbing - sound absorbing. Polypropylene foams are also relatively rigid,  d. H. their elasticity is too low, so that the achievable Soundproofing and soundproofing are in need of improvement.

From DE-GM 71 08 754 is a vacuum-drawn interior lining known from a crosslinked polyethylene foam, the be heat-sealed to the body parts can. This is also a closed cell Foam, whose sound-absorbing properties are inadequate are. Such cross-linked polyolefin foams closed-cell structure z. B. in DE-AS 16 94 130, DE-OS 15 69 465, DE-AS 28 39 733, DE-OS 30 32 635 and DE-OS 31 32 430 method described.

So far we have predominantly used for sound insulation and damping open-cell soft foams based on polyurethane Application found.

The invention has for its object an interior paneling based on a cross-linked polyolefin foam to create improved sound absorption, which at the same time the Advantage of economical production, such as for mass products is required.

The invention solves the problem with an interior paneling according to the characterizing feature of claim 1.

The foam sheet used according to the invention enables with their skin-covered side of the plate applying an adhesive, that cannot penetrate into the interior of the foam and so there cannot and does not lead to hardening at the same time an air-impermeable layer that allows one-sided deformation the foam board by means of vacuum or overpressure.

The large-cell open side of the foam sheet enables good sound absorption, as was previously the case with closed cells cross-linked polyolefin foams cannot be achieved was.  

Preferred embodiments of the foam sheet according to the invention can be inferred from the features of claims 2 to 6 and 9.

The good sound absorbing and sound absorbing properties through the combination of coarse-celled and soft-elastic tough properties of the ethylene-propylene rubber portion and of the selected ethylene copolymers of the invention Foam achieved. The required coarse cell structure of the foam is achieved through the interaction of several measures achieved, and is based in particular on the use of very fine-grained Blowing agent, very fine-grained, uniform fillers and a not too high proportion of the 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.

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 for improvement in order to achieve electrical volume 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 sheet according to the invention, proportions of 10 to 25 parts by weight of ethylene-propylene polymer and / or ethylene-propylene terpolymer in the molding composition, based on 100 parts by weight of a copolymer based on ethylene, are used, resulting 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 sheet 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 and preferably pores with a diameter greater than 2 mm should comprise 30% of the foam volume. 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., 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 15 to 50 J / g.

The foam sheets have a gel content in the range from about 50 to 90%, preferably from 60 to 85%. The Degree of crosslinking, d. H. the gel content is at 6 hours of extraction of the cross-linked foam at 135 ° C with decahydronaphthalene measured as a solution extractant. (ASTM-D 2765-68)  

The foam sheets have densities below 100 kg / m ³ , 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 ethylene and vinyl acetate or acrylate) are preferably used. The known additives used in the production of polyolefin foams, such as. B. light stabilizers, pigments, fillers, flame retardants, mold release agents, lubricants or the like. Can also be contained in the foam sheets according to the invention.

Corresponds to the partially open-pore structure of the foam an absorbable amount of water which is at least 200% by weight based on the weight of the foam used, preferably over 300% by weight and particularly preferably over 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 .

Unless the foam sheet is cross-linked by blasting but peroxidic, becomes a peroxidic crosslinking agent in an amount of about 0.4 to 1.5 parts by weight per 100 parts by weight of copolymer of ethylene used, the 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-butylperoxiisopropyl) - benzene.

Interior linings from the foam sheets according to the invention indicate that for the deformation by deep drawing, Vacuum molding, overpressure molding, pressing required heat deformability, Heat resistance, shape retention and the desired soundproofing properties.

According to a preferred embodiment of the interior cladding, it is provided that the coarse-cell, open panel side of the foam panel is laminated with a thermoformable decorative layer made of a thermoplastic, if appropriate perforated or embossed film, and, if appropriate, printed textile fabrics made of natural and / or synthetic fibers. The lightly shaped interior linings are preferably glued directly to body parts or carrier materials, over their full or partial area. Depending on the type and time of attachment and materials, pressure sensitive adhesives or contact adhesives or hot melt adhesives are suitable for this. For example, pressure sensitive adhesives based on PVAC or polyvinyl acrylate can be used. According to a preferred embodiment of the invention, an adhesive can be applied over the entire surface or in partial areas to the skin-covered side of the foam sheet. The interior trim so equipped is then directly on a body part, for. B. inside of the roof, wheel arch inner surface, side wall, glued. A special and preferred embodiment of the interior trim is provided in the form of an automobile roof. In this case, a foam sheet with a density less than 60 kg / m ³ , an average pore diameter greater than 0.8 mm, a water absorption greater than 200% based on the weight of the foam used is preferably used.

The foam sheets can, for example, according to the DE-PS 16 94 130 or DE-PS 31 32 439 described method getting produced. The fact that the foam sheets without Applying external pressure or molding continuously in Sheets are made form the surfaces of the foam sheets  a compact skin. This skin can have a thickness of have at least about 5 µm. For achieving a large pore size Foam is to be noted in the production that without additional tempering or storage crosslinked and foamed becomes. In the case of crosslinking carried out using rays the foaming is then carried out while at peroxidic crosslinking partially overlapping with the Foaming can be done.

To achieve better open cell, i. H. a larger one The number of open cells can be made from the foam sheets still mechanically post-processed, 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.

A soundly suitable, coarse-pored foam sheet is also obtained when foam waste on the same basis of the composition of the mixture and / or of pure PE foam in the form of compacted chips, chips, Granules or the like up to 20% by weight be processed. In the method of manufacturing an interior trim are covered with a decorative layer Foam sheet blanks in the form of foam sheets punched and the foam sheets after heating up a temperature sufficient for permanent deformation Apply pressure to the desired three-dimensional Configuration deformed.

Since the foam sheets are covered on all sides by a skin enclosed surface are produced, are suitable in this form because of the softness of sound for sound attenuation, d. H. for noise reduction due to vibrations deformations occurring. In a further embodiment the invention proposes that for Manufacture of interior panels at least on one  Part of the surface of the foam sheets removed the skin so that the coarse-pored surface that emerges in this way can be used for airborne sound absorption. A special one advantageous treatment of the continuously produced Foam sheet overlooks the cleavage 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 open cell surface with sound absorption properties exhibit. The open cell surface will vary depending on the use the foam sheet with a deep-drawable textile Decorative layer, for example fabric or fleece or the like. concealed. The blanks made from it will be after heating to a temperature of about 110 to 140 ° C in a form pressed, blown or deep-drawn, the skin-coated side of the foam sheet against the mold brought. The foam sheet can be particularly advantageous with differently designed surfaces Deep drawing or overpressure forming using heat and pressure on interior trim parts such as car headlining, Deform side panels, wheel arch linings.

This is made possible in particular when deep drawing or vacuum forming the compact surface of the foam sheet the application of the Vacuum and the perfect deformation of the foam the desired structure. The interior trim can also still be formed with recesses depending on the configuration of the Body parts. After the interior trim has been removed from the mold the back, d. H. the compact skin side, with a Apply glue. As a rule, this only happens on site. H. when installing the interior trim in the motor vehicle. Contact adhesives are also suitable for this purpose. B. sprayed will.

The decorative layer can be split with the open side Foam sheet, for example, are flame-laminated or connected by means of an applied hot melt adhesive layer will. The foam panels used for the interior panels  preferably have a thickness of 5 to 15 mm on. For thicker interior panels, it is also possible to use two foam sheets, for example be connected point by point, e.g. B. by needling or gluing.

The invention is illustrated in the following examples and the Drawing explained by way of example.

Show it

Fig. 1 is a foam sheet in cross section

Fig. 2 is a headliner, in perspective

Fig. 3 is a plan view of the open cell side of a foam sheet

Fig. 4 absorption curves of the foam sheet or an interior panel

Fig. 5 shows a schematic cross section through a molding tool.

In Fig. 1, the foam sheet 10 is shown schematically in cross section, which is deformed into an interior paneling. The coarse-cell, relatively evenly structured foam sheet 10 with the pores 3 made of a partially cross-linked, partially open-cell elastic foam based on polyolefin and EPM and / or EPDM has a compact, almost impermeable sheet side 11 , which has a skin with a thickness of at least about 0.005 mm is formed. The opposite plate side 12 is open with large cells. The side 12 is covered with a decorative layer, e.g. B. a perforated leatherette, fleece, fabric, knitted fabric or the like. Laminated. This decorative layer closes the open cells and prevents dirt from entering the foam. It also serves aesthetic purposes. Fig. 2 shows in einfachster training in view of a car roof 1, produced by deep drawing a correspondingly cut or punched foam board 10 with laminated fabric 2.

An adhesive is applied to the pelted side 11 of the automobile headliner for attachment to the body roof during assembly. The foam layer 10 now has a sound-absorbing effect on the vehicle interior against noise coming from outside and likewise absorbs noise in the vehicle interior via the open-cell inside.

In FIG. 3, the photographic top plan view of the not-clad side 12 of the foam sheet 10 of a foam produced according to the following example, in scale 1: 1 shown. The large-celled open, but relatively uniform structure of the pores is clearly visible. The pore size is on average over 1 mm and results in a foam with good sound-absorbing properties and low weight.

In FIG. 4, sound absorption curves, measured at Apamat used for the interior trim foam sheets shown.

The absorption was measured using the foam plate produced according to Example 1, namely the sound intensity as a function of the frequency. Curve A shows the measured sound absorption of a cotton fleece with a weight per unit area of 1100 g / m ² , which has a good sound absorption capacity, as a comparison.

Curve B shows the absorption curve of a 6 mm thick foam sheet 10 , 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 .

Curve D shows the absorption curve of an interior cladding with a foam sheet 10 according to Example 1 with a thickness of 6 mm, which is laminated on the open side with a polyester fleece with a basis weight of 150 g / m ² and thus a total basis weight of 320 g / has m ² .

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

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

The recipe components are used to manufacture the foam sheets without decomposing the added organic peroxide and the added foaming agent at temperatures in the range up to mixed to about 110 ° C, e.g. B. with rollers or Banbury mixer and then with an extruder to the matrix (a thickness of 2-5 mm and Width of 30-50 cm) extruded. The matrix is then directly z. B. by a heated by hot air from about 190 to 240 ° C. Channel led in which they are networked to form a foam sheet with a thickness - depending on the matrix thickness and density - of foams 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 parts by weight of Mg O 20.0 parts by weight . Parts of CaCO ₃ with an average particle diameter of 3 µm and maximum particle diameter of 10 µm
is made as described above, a foam and separated with a band knife with the following features:

Thickness of the foam sheet 6 mm density 36 kg / m ³ degree of crosslinking (gel content) 77% average pore diameter of 2-3 mm (at least 50% volume fraction of the foam) maximum pore diameter approx. 4 mm water absorption435%

The foam sheet is split into two foam sheets with thicknesses of 6 mm or 4 mm with one skin each and an open cell surface side.  

Example 2:

The 6 mm thick foam sheet produced according to Example 1 is connected on its open-cell side to a polyester fleece with a basis weight of 150 g / m ² by flame lamination. From this, blanks are punched for the desired shape of the interior trim. The blanks are z. B. IR radiator heated to 140 ° C and placed in a deep-drawing mold 4 , as shown in Fig. 5, and fixed on the edge by means of the clamping frame 5 . The fleece-laminated side 2 of the foam plate 10 points upwards, while the skin-covered side 11 comes to rest against the mold wall. The vacuum is applied via the channels 41 .

The cell structure of the foam sheet remains during the deformation essentially preserved unless particularly densified Areas to be trained. The interior trim produced can still be broken through later Punching out.

Claims (11)

1. Interior lining for a motor vehicle, from a foam plate permanently deformed using heat and pressure to the desired three-dimensional configuration, from a cross-linked polyolefin foam, which has a density of less than 100 kg / m ³ , with a laminated decorative layer, characterized in that the foam sheet made of a sound-proof, elastic, partially open-cell, coarse-pored, partially cross-linked foam with an average pore size of greater than 0.6 mm, in particular greater than 1 mm, a water absorption greater than 200% by weight based on the weight of the foam used, based on a mixture polyolefins and ethylene-propylene rubber, a foaming agent and possibly a crosslinking agent, and one side of the plate has an almost impermeable skin, even a non-foamed mixture, and the opposite side of the plate has a large open cell structure. Interior cladding according to claim 1, characterized in that a foam sheet based on a mixture of 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 5-50 wt. Parts 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, with 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 propylene 0-100% by weight. Parts of a filler with a particle diameter of less than 50 .mu.m, as well as, if appropriate, the usual amounts of additives from the series of light stabilizers, pigments, flame retardants, antistatic agents and lubricants. 3. Interior paneling according to claim 1 or 2, characterized in that a foam sheet, which 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 ) from 1-20, preferably 2-12 g / 10 min. and a density of 0.930 to 0.955 g / cm ³ and / or as a copolymer based on ethylene and acrylate, an ethylene-butyl acrylate with a butyl acrylate content of about 10-30% by weight 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 contains, is provided. 4. interior lining according to one of claims 1 to 3, characterized in that a Foam sheet in which on 100 parts by weight of a copolymer based on ethylene 10 to 25 parts by weight of ethylene-propylene polymer and / or Ethylene propylene terpolymer are included, is provided. 5. interior lining according to one of claims 1 to 4, characterized in that a Foam sheet used as a filler to 100 parts by weight Copolymers of ethylene and vinyl acetate or acrylate  5 to 40 parts by weight of chalk with a particle diameter smaller than 20 µm, in particular smaller 10 µm contains, is provided. 6. interior lining according to one of claims 1 to 5, characterized in that a Foam sheet, which is a foaming agent with higher Decomposition temperature as the crosslinking agent, in particular Azodicarbonamide, with an average particle diameter contains less than 10 µm, is provided. 7. interior lining according to one of claims 1 to 6, characterized in that the large-cell open plate side of the foam plate with a thermoformable decorative layer if necessary perforated or embossed film, if necessary printed textile fabrics made of natural and / or synthetic Fibers, is laminated. 8. interior lining according to one of claims 1 to 7, characterized in that on the skin-glued plate side of the foam plate an adhesive is applied over the entire surface or in partial areas. Interior cladding according to one of claims 1 to 8, characterized in that a foam sheet made from 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 10 to 25 parts by weight. Parts of a semi-crystalline ethylene-propylene copolymer and / or a semi-crystalline ethylene-propylene terpolymer that have a tensile strength greater than 5 N / mm ² , in particular greater than 8 N / mm ² , a Mooney viscosity (ML 1 + 4) 100 ° C greater 50 and a heat of fusion Δ H _s according to the DSC method greater than 10 J / g, produced from 55-80% by weight of ethylene, 0-10% by weight of a ter component, in particular ethylidene norbornene or 1.4 hexadiene and 10-45% by weight .-% propylene, and 5 to 25 parts by weight of azodicarbonamide with a particle diameter of less than 10 microns as a foaming agent and 0.4 to 1.5 parts by weight of a peroxidic crosslinking agent, in particular dicumyl peroxide or bis (-t-butylperoxyisopropyl) benzene and 5-40 parts by weight it finely divided filler, in particular chalk with a particle diameter of less than 20 μm, which has a degree of crosslinking of 50 to 90%, a density below 70 kg / m ³ , a water absorption greater than 200% based on the weight of the foam used, and an average pore diameter greater than 0 , 8 mm,
is provided. 10. Interior lining according to one of claims 1 to 9, characterized in that it is configured as a headliner and a foam sheet with a density less than 60 kg / m ³ , an average pore size greater than 0.8 mm, a water absorption greater than 200% based on that Contains weight of the foam used. 11. Method of making an interior trim panel according to one of claims 1 to 9, in which one with a decorative layer laminated foam sheet blanks  are punched in the form of foam sheets, the foam sheets after warming up to a permanent one Deform sufficient temperature using pressure deformed to the desired three-dimensional configuration are characterized in that a continuously produced on both sides of the web an almost impermeable skin equipped foam sheet from a partially cross-linked, partially open-celled, coarse-pored foam based on a mixture of Polyolefins and ethylene-propylene rubber is split, the now coarsely open gap side of the foam sheet is laminated with a thermoformable decorative layer and the blanks produced therefrom, if necessary, after heating pressed a temperature of about 110 to 140 ° C in a mold or deep drawn, the skin side of the Foam sheet is brought to bear on the mold.