DE102014226677A1 - Thermally expandable molded parts - Google Patents

Abstract

The present application relates to thermally expandable molded parts containing an at least partially compressed polymer foam and at least one hot-melt adhesive containing an alpha-olefin copolymer, acoustic damping materials that can be obtained from these moldings and a method for acoustic damping of structures based of these moldings.

Description

The present application relates to thermally expandable molded parts containing an at least partially compressed polymer foam and at least one hot-melt adhesive, acoustic damping materials that can be obtained from these moldings and a method for acoustic damping structures based on these moldings.

In vehicles it can happen that vibrations, which are generated for example by the engine, a pump or the transmission, by means of the structural elements to an emitting surface, such as a sheet, transmitted and emitted there as unwanted structure-borne noise. There have been a number of approaches in the past to eliminate such noise sources. A reduction of structure-borne noise is usually by means of insulation and / or Absorbtionsmechanismen.

For example, in the WO2007 / 039309 and the WO2009 / 036784 thermally expandable materials described that absorb the distribution of vibrations in structures particularly effective and thus significantly reduce the noise level caused by structure-borne noise. These materials are placed in the body during the construction of the shell in the unfoamed condition; the thermal expansion then usually takes place during the passage of the produced vehicle body through the oven for curing the cathodic dip painting. In the expanded state, these materials have a closed-pore structure, which leads to an advantageous low water absorption.

In contrast to such foams with a closed pore structure, open-pored structures are even more effective in absorbing unwanted vibrations. So foams under the trade name Basotect ^® are sold for example by BASF that are distinguished by their good acoustic absorption and are also referred to as "sound absorber". When using such materials for noise reduction in vehicle construction corresponding moldings would have to be made, which are accurately adapted to the particular application, which means a large individuality with a correspondingly high production cost of the individual moldings. In addition, a gap formation between the material and the body can not be completely excluded in such prefabricated moldings. Furthermore, it is technically difficult to accurately fit the molded parts adapted to the geometry of the structures in the body shop, and after the introduction of a uniform application of liquids, such as paints in the damped structures is no longer possible. Another disadvantage of such acoustically effective materials is the strong water absorption of the open-celled foams.

In the EP-A2-1 125 719 It is proposed to compress shape memory foam parts under the action of heat and to cool them in the compressed state. Such structures can then be converted to the uncompressed state at the point of use by renewed heating and thus anchored precisely in the structure. Foams based on EPDM, nitrile rubber, styrene-butadiene rubber or even natural rubber are preferably used. The uncompressed structures, however, may again tend to absorb water.

The means of the prior art have not yet fully meet all requirements for such acoustic effective moldings.

Accordingly, it is an object of the present invention to provide acoustically effective molded parts which are distinguished by excellent damping properties and a simple production process, can easily adapt to the given geometries without the formation of gaps and yet do not have the disadvantage of a high water absorption.

It has now been found that thermally expandable moldings which contain an at least partially compressed polymer foam and a hot-melt adhesive, meet the requirements placed on acoustic materials in vehicle construction to a high degree.

A first subject of the present invention are therefore thermally expandable moldings, comprising at least one polymer foam and at least one hot-melt, non-reactive adhesive containing at least one olefin copolymer based on ethylene or propylene, in particular ethylene, and at least one other alpha-olefin , wherein the polymer foam is in at least partially compressed state, and the adhesive is arranged so that it fixes the polymer foam in the compressed state at temperatures below 50 ° C.

Corresponding molded parts can, as shown, be produced in a particularly manufacturing process, wherein the expanded structures produced from the molded parts have excellent damping properties. In this case, the expanding moldings can easily adapt to predetermined geometries without the formation of gaps, yet they do not have the disadvantage of high water absorption. In addition, the moldings are easy to store and stable in storage, wherein the moldings do not disintegrate during manufacture or in the expansion or damaged in their structure, as is often observed in the prior art.

A first component essential to the invention is the polymer foam. Polymer foams having a substantially open-cell cell structure are preferred according to the invention.

The polymer foams are preferably selected from foams based on melamine resins (condensation products of melamine with formaldehyde), polyurethanes, ethylene vinyl acetates, polyolefins, polystyrene, polyvinyl chloride, polyamides, epoxy resins, polyethers, polyesters and / or rubbers. Particularly good acoustic properties can be achieved if polymer foams based on melamine resins, polyurethanes and / or ethylene-vinyl acetates are used.

Furthermore, it is advantageous according to the invention if the untreated polymer foams in the uncompressed state have a density of from 1 to 300 kg / m ³ , in particular from 3 to 100 kg / m ³ .

According to the invention particularly preferably open-cell melamine resin foams, such as those sold by BASF under the trade Basotect ^® are.

The second constituent of the thermally expandable molded parts essential to the invention is at least one hot-melt, non-reactive adhesive. A "non-reactive adhesive" is understood according to the invention to mean an adhesive whose components undergo no chemical curing reaction when heated. Such adhesives can be almost completely reversibly melted several times and cooled again.

A necessary ingredient of the adhesive are olefin copolymers based on ethylene or propylene, especially ethylene, and at least one other alpha-olefin, preferably a C3 to C20 alpha olefin. A preferred embodiment of the invention uses such co- or terpolymers based on ethylene or propylene, in particular ethylene, together with at least one C4 to C20-alpha-olefin, in particular C6 to C12-alpha-olefin, more preferably at least one C8-olefin. These polyolefins can be prepared via metallocene catalysis. The monomers which may be used in addition to ethylene or propylene are the known olefinically unsaturated monomers copolymerizable with ethylene or propylene. In particular, they are linear or branched C4 to C20-alpha-olefins, such as butene, hexene, methylpentene, octene; cyclic unsaturated compounds such as norbornene or norbornadiene. Preferably, at least one ethylene-1-octene copolymer is included.

The number average molecular weight of the copolymers is usually below 200,000 g / mol, in particular below 100,000 g / mol, very particularly preferably below 30,000 g / mol. The preferred lower limit of the number average molecular weight Mn is 2000 g / mol, in particular 3000 g / mol (measured by GPC against a polystyrene standard). These copolymers are characterized by having a narrow molecular weight distribution. Such polymers are known in the literature and can be obtained commercially from various manufacturers. For example, suitable polymers are commercially available under the trade name Affinity or Infuse. The suitable copolymers are preferably block copolymers. The blocks have a different composition of the monomers.

In a preferred embodiment, the copolymers which are suitable according to the invention have a glass transition temperature; in a particularly preferred embodiment, the adhesive according to the invention should also have a glass transition temperature, the glass transition temperature (Tg) (measured via DTA) being in the range from -100 to 0 ° C., in particular between -80 to -10 ° C.

It has proved to be preferred according to the invention, when hot-melt, non-reactive adhesives are used with a softening point of at most 170 ° C, in particular a softening point between 50 and 170 ° C, preferably between 50 and 150 ° C, more preferably between 60 and 100 ° C. The "softening point" of the thermally expandable molding is in the context of the present invention by means of the "ring and ball" method according to ASTM E-28 determined, wherein preferably a ring and ball machine HRB 754 Walter Herzog GmbH is used.

Depending on the field of application, hot-melt, non-reactive adhesives with slightly different softening ranges may be preferred. For example, it is particularly preferred to use hot-melt, non-reactive adhesives with a softening range of 140 ° C. to 170 ° C. Such adhesives are particularly preferred when the expansion of the moldings takes place in the shell furnace. Alternatively, hot-melt non-reactive adhesives having a softening range of 50 ° C-140 ° C, especially 60 ° C-100 ° C, may be particularly preferred. This is advantageous, for example, if the expansion of the moldings according to the invention is to be initiated without the use of a shell furnace.

Furthermore, it has proved to be advantageous if the polymers used have thermoplastic properties and / or a substantially linear structure. Furthermore, it is preferred according to the invention if the hot-melt non-reactive adhesives used are non-tacky in the temperature range below 50.degree.

According to the invention, embodiments are encompassed in which the at least one olefin copolymer according to the invention is the sole constituent of the hot-melting, non-reactive adhesive, preferably the adhesive substantially contains only the olefin copolymers described, in particular more than 95% by weight, based on the total weight of the adhesive, preferably more than 99 wt .-%, more preferably exclusively the described olefin copolymers.

However, embodiments are also encompassed in which the hot-melt, non-reactive adhesive contains further constituents in addition to the polymer (s). In this embodiment, the olefin copolymers according to the invention preferably have a proportion of 50 to 95 wt .-%, in particular 60 to 80 wt .-% of the total amount of hot-melt, non-reactive adhesive.

Thus, it may be preferred according to the invention, when the hot-melt, non-reactive adhesive in addition to the olefin copolymers at least one tackifying resin and / or at least one further additive.

In principle, it is possible to use the known tackifying resins, such as, for example, aromatic, aliphatic or cycloaliphatic hydrocarbon resins and also modified or hydrogenated natural resins. Suitable resins which can be used in the invention are, for example, terpene resins, such as terpolymers or copolymers of terpene, modified natural resins, such as gum rosin, tall resin or rosin, optionally also hydroabietyl alcohol and its esters, acrylic acid copolymers, such as styrene-acrylic acid copolymers or copolymers of ethylene, acrylate esters and maleic anhydride, or resins based on functional hydrocarbon resins. Also useful as useful tackifying resin are low molecular weight reaction products consisting of the above-mentioned ethylene / propylene-α-olefin polymers. The molecular weight of such polymers is usually below 2000 g / mol.

These are in particular resins which have a softening point of 80 to 130 ° C ( ASTM method E28-58T ). Particularly preferred tackifying resins are hydrocarbon resins. Another particular embodiment uses resins which have a softening point below 50 ° C, in particular, these may also be liquid. The tackifying resins are generally used in an amount of 10 to 65 wt .-%, in particular 25 to 60 wt .-%, each based on the mass of the hot-melt, non-reactive adhesive.

Another important ingredient according to the invention are plasticizers. These may be, for example, medicinal white oils, naphthenic mineral oils, polypropylene, polybutene, polyisoprene oligomers, hydrogenated polyisoprene and / or polybutadiene oligomers, benzoate esters, phthalates, adipates, vegetable or animal oils and derivatives thereof. Hydrogenated plasticizers are selected, for example, from the group of paraffinic hydrocarbon oils. Also, polypropylene glycol and polybutylene glycol, and polymethylene glycol are suitable. It also esters are used as plasticizers, such as liquid polyesters and glycerol esters. The molecular weight of polyalkylene glycols or polybutenoligomers should be from 200 to 6,000 g / mol, polyolefins should have a molecular weight of up to about 2000 g / mol, in particular up to 1000 g / mol. In particular, white oils, mineral oils, polybutenes and liquid or pasty hydrogenated hydrocarbons are preferred according to the invention.

The amount of plasticizer is according to the invention between 0 to 35 wt .-%, based on the total amount of the hot-melt, non-reactive adhesive. In particular, the proportion of plasticizers is between 3 to 30 wt .-%, in a very particular embodiment, between 5 to 15 wt .-%, each based on the total amount of hot-melt, non-reactive adhesive.

Optionally, waxes may be added to the hot-melt non-reactive adhesive in amounts of from 0 to 30% by weight, preferably from 0.5 to about 5% by weight, based in each case on the total amount of hot-melt, non-reactive reactive adhesive. The amount is dimensioned so that on the one hand, the viscosity is lowered to the desired range, on the other hand, the adhesion is not adversely affected. The wax may be natural, optionally also in chemically modified form, or of synthetic origin. Vegetable waxes, animal waxes, mineral waxes or petrochemical waxes can be used as natural waxes. Hard waxes such as montan ester waxes, sasol waxes and so on can be used as the chemically modified waxes. As synthetic waxes find polyalkylene waxes and polyethylene glycol waxes use. Preferably, petrochemical waxes such as petrolatum, paraffin waxes, microcrystalline waxes and synthetic waxes are used.

The hot-melt, non-reactive adhesives according to the invention may contain, in addition to the abovementioned constituents, further constituents which are customarily used in such adhesives as additives. These include, for example, stabilizers, adhesion promoters, antioxidants, fillers and / or pigments. The amount of the additives and additives may be 0.01 to 30 wt .-%, in particular from 0.1 to 15 wt .-%, each based on the total amount of the hot-melt, non-reactive adhesive.

Additives, such as stabilizers or adhesion promoters are known to the person skilled in the art. They are commercial products and the skilled person can select them according to the desired properties. It is important to ensure that a compatibility with the polymer mixture is given.

Furthermore, fillers in concentrations of 0 to 10 wt .-%, based on the total amount of hot-melt, non-reactive adhesive can be used to improve the performance and adhesive properties. These may be, for example, dyes or fillers such as titanium dioxide, zinc oxide, gypsum, barite, clay, chalk and the like.

The hot-melt non-reactive adhesive used in the present invention is prepared by melt-blending by known methods. In this case, all components can be presented simultaneously, heated and then homogenized, or it is first presented the lighter-melting components and mixed, then added the other resin components. It is also possible to produce the hot melt adhesive continuously in an extruder. The suitable hotmelt adhesive is solid and, except for impurities, free from solvents.

The hot-melt, non-reactive adhesive suitable according to the invention preferably has a viscosity of from 500 to 30,000 mPas, preferably from 1,000 to 20,000, in particular from 3,000 to 10,000 mPas at 177 ° C. (Brookfield, US Pat. ASTM D 1084 ) on.

The hot-melt, non-reactive adhesive according to the invention can be well adapted to different applications. In a particular embodiment, the hot melt adhesive is used for spray application. There are used as plasticizers in particular mineral oils based on paraffin or naphthenic, polybutenes or hydrogenated hydrocarbons. These plasticizers should have a viscosity between 25 and 300 mPas, in particular between 100 and 250 mPas, measured at 20 ° C. In this embodiment, the hot-melt, non-reactive adhesive according to the invention has a viscosity of 500 to 6000 mPas, in particular between 700 to 2000 mPas measured at temperatures between 120 to 160 ° C.

The thermally expandable moldings according to the invention containing preferably 50 to 95 wt .-%, in particular from 60 to 90 wt .-%, preferably from 75 to 85 wt .-% of a hot-melt, non-reactive adhesive, each based on the thermally expandable body of the molding. The term "based on the thermally expandable body of the molded part" is understood according to the invention to mean that region of the molded part whose shape changes during heating; that is, the proportions of the support materials and fasteners are not taken into account in this consideration.

The thermally expandable molded parts according to the invention contain the above-described components according to the invention in such a way that the polymer foam is in at least partially compressed state, and the hot-melt, non-reactive adhesive is arranged so that it compresses the polymer foam in the compressed at temperatures below 50 ° C. Condition fixed.

It may be preferred in one embodiment that the total polymer foam is compressed in the direction of its shortest extension axis to less than 20%, in particular to less than 10% of its original extent in this direction.

In a preferred embodiment of this article of the present invention, the thermally expandable molding after compression has a non-porous surface. In particular, the expandable molding is completely enclosed with the hot-melt non-reactive adhesive, the adhesive forming a non-open-pore closed surface. Corresponding moldings are particularly stable on storage and do not tend to absorb water during storage.

In a further preferred embodiment of this article of the present invention, the thermally expandable molded part has at least one fastening element. In this case, preferred fastening elements according to the invention are clips, adhesive strips, screwable, rivetable, clampable or bondable metal or plastic parts or weldable metal strips.

Although the thermally expandable molded parts according to the invention are generally introduced without further reinforcing elements in the structures to be damped, it may also be preferred in another embodiment, if the thermally expandable molding according to the invention additionally a support, for example in the form of a stable film or a cover plate , having.

As support materials are preferably thermoplastic materials which are sufficiently resistant to fracture under normal conditions of use and have a melting or softening point, which is above the temperature of production of the structure to be damped, preferably above 190 ° C, more preferably above 220 ° C to Commitment. Preferably, the support is made from a variety of polymeric materials such as polyesters, aromatic polyethers, polyether ketones, and especially polyamides such as nylon-66. The carrier material may contain, in addition to the polymeric ingredients, other additives and fillers, such as dye and / or reinforcing fibers. Alternatively, the carrier can also be made of metal, such as steel or aluminum.

The carrier can be connected by means of the essential hot-melt, non-reactive adhesive according to the invention with the molded part. However, it is also an embodiment conceivable in which the fixation is done via a different type of adhesive. An alternative and / or additional fixation of the thermally expandable molded part on the carrier by means of mechanical fastening elements is also an object of the present invention.

It may be preferred that furthermore at least one fastening element is fastened to the carrier, which serves for fixing the thermally expandable molded part in the structure to be damped. With regard to the preferred fastening elements, reference is made to the above statements. A carrier plate carrying one or more clips may be particularly preferred. It may be preferred according to the invention, when the carrier plate is designed such that it is impermeable to air, sound and liquids; but also a perforated carrier plate is suitable. A carrier material, which also makes an acoustic attenuation contribution itself, may be particularly preferred. Moreover, it is conceivable that the thermally expandable molded parts according to the invention are enclosed by two carrier plates.

To produce the thermally expandable molded parts according to the invention, the polymer foam is coated in a first step with the at least one hot-melt, non-reactive adhesive.

In a first embodiment of the present invention, it is preferred if the polymer foam has at least two substantially parallel surfaces before compression.

In a second embodiment of the present invention, it is preferred if the polymer foam has an irregular shape, possibly adapted to the subsequent application, prior to the compression. According to the invention, a "mold adapted to the application" is understood to mean all geometries of molded parts which ensure complete sealing of a cavity of the structure to be damped after expansion. In this case, the molding can be individually modeled on the shape of the cavity and have corresponding tips and / or curves; but it can also be sufficient to introduce a correspondingly large amount in variable form, for example in the form of a strip-shaped thermally expandable molding in the cavity to ensure a complete seal of the cavity after expansion.

The term "coating" is broadly defined according to the invention. Thus, it is conceivable that the hot-melt, non-reactive adhesive is applied as a solid on the polymer foam. A fixation with an additional, liquid adhesive is conceivable in this stage. In another preferred embodiment, the hot-melt non-reactive adhesive is melted and applied to the polymer foam in a molten state. In this case, he can impregnate the polymer foam completely or even partially, or even be distributed only externally. A spray application of the molten hot-melt, non-reactive adhesive is conceivable. It is particularly preferred if the hot-melt, non-reactive adhesive is applied in the molten state to the polymer foam and penetrates it on the surface.

The polymer foam may preferably be completely enclosed with the hot-melt, non-reactive adhesive. But it is also conceivable that only partial areas, such as opposite surfaces, of the polymer foam are brought into contact with the hot-melt, non-reactive adhesive. In a preferred embodiment of the present invention, at least 60%, in particular at least 80%, preferably at least 95% of the outer surface of the polymer foam is coated with the hot-curing, non-reactive adhesive. Further, the hot-melt, non-reactive adhesive can be applied in any irregular shape to the polymer foam; For example, a point-shaped application depending on the desired compression of the polymer foam is conceivable.

In a second step of the production process, the polymer foam coated with the hot-melt, non-reactive adhesive is compressed at a temperature of at least 80 ° C., in particular at least 120 ° C., preferably at least 170 ° C. and held at this temperature for a time. This can be done for example by means of a heatable platen press or a more punctually acting pliers press. In addition, the use of special molds that exert pressure only on certain areas of the polymer foam, conceivable.

It may be preferred according to the invention if, for the compression of the polymer foam, an external pressure is applied which acts on the polymer foam substantially along a spatial dimension. However, it can also be preferred according to the invention if an external pressure is applied for compression, which acts on the coated polymer foam in the direction of several, preferably in the direction of two or three mutually perpendicular spatial dimensions.

In a first embodiment of the present invention, it is preferred if the polymer foam has at least two substantially parallel surfaces before compression. In this embodiment, it is preferred that these surfaces are coated with the hot-melt, non-reactive adhesive and an external pressure is applied for compression which acts substantially perpendicularly to these mutually parallel surfaces.

In a second embodiment of the present invention, it is preferred if the polymer foam has an irregular shape, possibly adapted to the subsequent application, before compression, and an external pressure is applied for compression in the direction of several, preferably in the direction of two or three, to each other vertical space dimensions acts on the coated polymer foam.

It may be preferred according to the invention, if an adhesion of the contact surfaces of the press with the coated polymer foam is avoided, for example, by the use of silicone paper.

Subsequently, the coated polymer foam in the compressed state, that is, without reducing the applied external pressure, preferably cooled to room temperature, but at least to a temperature below the softening point of the used hot-melt, non-reactive adhesive and only then the applied pressure is released ,

In one embodiment of the present invention, after the pressure has been released, the finished and ready-to-use thermally expandable molded part is already obtained. However, it may also be preferred according to the invention to use larger plates of a suitable polymer foam, to coat them on their surface and lower surface with the hot-melt, non-reactive adhesive, and then compress them in the direction of their smallest spatial extent according to the method described above. From the resulting after solution of the external pressure compressed plates can in the context of this embodiment then if necessary, the thermally expandable molded parts according to the invention, for example by cutting or punching, are obtained.

Accordingly, another object of the present invention is a process for producing a thermally expandable molding according to the invention, in which a polymer foam is coated in a first step with a hot-melting, non-reactive adhesive, the coated polymer foam in a second step at a temperature of at least 80 ° C, in particular of at least 120 ° C, preferably of at least 170 ° C is compressed and then cooled in the compressed state.

With respect to the details of this subject matter of the present invention, mutatis mutandis, what has already been said about the other objects applies.

The thermally expandable molded parts according to the invention can then be introduced into the structures to be insulated during the manufacture of the shell and optionally fixed in them by means of the intended fastening elements.

The thermally expandable moldings according to the invention can be used in all products which have cavities. These are in addition to the vehicles, for example, aircraft, rail vehicles, household appliances, furniture, buildings, walls, partitions or boats.

Another object of the present invention is therefore a process for producing an expanded molded part, in particular for the acoustic damping of structures, wherein a thermally expandable molded part according to the invention introduced into a structure and then to a temperature above 80 ° C, in particular above 120 ° C. , is preferably heated above 170 ° C, so that the thermally expandable molded part expands. The molding preferably expands in at least one direction by at least 500%, in particular by at least 800%, preferably by at least 1100%, based on the expansion thickness of the molding in this direction before expansion.

Under acoustic attenuation according to the invention is understood to mean the absorption of the sound; A measure of the acoustic attenuation is the acoustic absorption coefficient, where an absorption coefficient of 1 stands for complete absorption of the incident sound.

• – im Terzband-Bereich von 250 Hz bis 630 Hz linear ansteigt (von α ≥ 0,1 bei 250 Hz bis α ≥ 0,5 bei 630Hz), und/oder
• – bei 630 Hz und im Terzbandbereich von 600 Hz bis 20 000 Hz im arithmetischen Mittel einen Absorptionskoeffizienten von α ≥ 0,5 aufweist.

It is particularly preferred if, with the aid of the method according to the invention, an acoustic absorption coefficient is achieved which

• - linearly increases in the one-third band range from 250 Hz to 630 Hz (from α ≥ 0.1 at 250 Hz to α ≥ 0.5 at 630 Hz), and / or
• - has an absorption coefficient of α ≥ 0.5 at 630 Hz and in the third-octave band from 600 Hz to 20 000 Hz in the arithmetic mean.

Particularly preferred are acoustic absorption coefficients which increase linearly in the third-octave band from 250 Hz to 630 Hz from α ≥ 0.2 at 250 Hz to α ≥ 0.65 at 630 Hz. Dampings in which the absorption coefficient α ≥ 0.65 in the range from 630 Hz to 10 000 Hz is also particularly preferred (arithmetic mean).

With respect to the details of this subject matter of the present invention, mutatis mutandis, what has already been said about the other objects applies.

Another object of the present invention is the use of the thermally expandable moldings according to the invention for the acoustic damping of structures.

Also with regard to the details of this subject matter of the present invention, mutatis mutandis, what has already been said about the other objects applies.

In the field of vehicle construction, it is particularly advantageous if the expansion of the thermally expandable molded part according to the invention takes place during the passage of the vehicle through the oven for curing the cathodic dip coating, so that it is possible to dispense with a separate heating step.

The acoustic damping materials, which are obtained by thermal expansion of the thermally expandable molded parts according to the invention, are the subject of the present invention.

According to the invention, such acoustic damping materials are particularly preferred in which the arithmetic mean of the acoustic absorption coefficient of the damping material is at least 0.2 in the measuring range from 20 to 20,000 Hz, especially at least 0.5 in the range from 250 to 5000 Hz.

With respect to the details of this subject matter of the present invention, mutatis mutandis, what has already been said about the other objects applies.

Finally, the structures themselves, which contain at least one acoustic damping material, which is obtained by heating a thermally expandable molded part, and have been provided with the aid of improved acoustic damping, part of the present invention.

With respect to the details of this subject matter of the present invention, mutatis mutandis, what has already been said about the other objects applies.

embodiments

A square of a commercially available under the name of Basotect from BASF ^® G open-cell melamine foam is coated on two opposite sides with a hot melt adhesive. As in Example 1, 3.64 parts by weight of Affinity 1950 (EtOc polymer, 17000 ° C. Viscosity 17000 C., melting point 70 ° C., Tg-57 ° C.) are used per part by weight of foam, for Example 2 4.82 parts by weight Affinity 1900 (EtOc polymer, Viscosity 8200 mPas at 177 ° C, melting point 68 ° C, Tg -72 ° C) per part by weight of foam used.

Subsequently, the thus coated foam is placed between two coated with silicone paper steel plates and compressed by means of applied metal brackets at 180 ° C for 30 minutes to a volume of less than 10%. After cooling to room temperature, a 3mm thick plate with a closed, non-porous surface is obtained. These moldings were particularly storage stable.

The molded part thus produced is heated in an oven. Table 1 shows the course of the expansion depending on the temperature. Table 1: Expansion rates of the molded part as a function of the temperature. Temperature [° C] Example 1 Expansion in% Example 2 Expansion in% 120 581 617 130 608 631 140 699 643 150 813 731 160 932 870 170 1024 909 180 1085 1152 190 1141 - 200 1186 1501

The expanded molded part had almost recovered its initial layer thickness after subsequent cooling. The polymer foam was soaked in the edge area with hot melt adhesive; However, he again had an open-pored structure. Characterized in that the edge region of the polymer foam is impregnated with hot melt adhesive, the resulting acoustic insulation material has a very hydrophobic surface, which significantly reduces the water absorption of the material. In addition, the expanded foams show excellent acoustic damping properties.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2007/039309 [0003]
• WO 2009/036784 [0003]
• EP 21125719 A2 [0005]

Cited non-patent literature

• ASTM E-28 [0019]
• ASTM Method E28-58T [0026]
• ASTM D 1084 [0034]

Claims (15)

 A thermally expandable molded part comprising at least one polymer foam and at least one hot-melt, non-reactive adhesive containing at least one olefin copolymer based on ethylene or propylene and at least one other alpha-olefin, wherein the polymer foam is in at least partially compressed state, and the adhesive is arranged so that it fixes the polymer foam in the compressed state at temperatures below 50 ° C. Thermally expandable molded part according to claim 1, characterized in that the polymer foam is selected from foams based on melamine resins, polyurethanes, ethylene vinyl acetates, polyolefins, polystyrene, polyvinyl chloride, polyamides, epoxy resins, polyethers, polyesters and / or rubbers. Thermally expandable molded part according to one of claims 1 or 2, characterized in that it is the compressed polymer foam is a foam having an open-cell structure and / or the untreated polymer foam in the uncompressed state has a density of 1 to 300kg / m ³ , in particular of 3 to 100kg / m ³ . Thermally expandable molded part according to one of claims 1 to 3, characterized in that the at least one olefin copolymer is a copolymer based on ethylene and at least one C3 to C20 alpha-olefin and / or the at least one olefin copolymer has a number average molecular weight between 2000 and 200000 g / mol and / or the at least one olefin copolymer has a glass transition temperature (Tg) in the range between -100 to 0 ° C. Thermally expandable molded part according to one of claims 1 to 4, characterized in that the hot-melt, non-reactive adhesive has a softening point of at most 170 ° C. Thermally expandable molded part according to one of claims 1 to 5, characterized in that the hot-melt, non-reactive adhesive more than 95 wt .-%, based on the total weight of the adhesive, preferably more than 99 wt .-% of at least contains an olefin copolymer. Thermally expandable molding according to one of claims 1 to 6, characterized in that the thermally expandable moldings 50 to 95 wt .-% of the hot-melt, non-reactive adhesive, in each case based on the thermally expandable body of the molding. Thermally expandable molded part according to one of claims 1 to 7, characterized in that it further comprises at least one fastening element, preferably the fastening element is selected from clips, adhesive strips, screwed, vernietbaren, clamped or glued metal or plastic parts or weldable metal strip. Thermally expandable molding according to one of claims 1 to 8, characterized in that further at least one side of the molding is covered with a stable film or end plate. A method for producing an expanded molded part, in particular for the acoustic damping of structures, wherein a molded part according to one of claims 1 to 9 introduced into a structure and then heated to a temperature above 80 ° C, so that the thermally expandable molded part expands. Use of a thermally expandable molding according to one of claims 1 to 9 for the acoustic damping of structures. Acoustic damping material obtainable by thermal expansion of a molded part according to one of claims 1 to 9, in particular by more than 500%. Acoustic damping material according to claim 12, characterized in that the arithmetic mean of the acoustic absorption coefficient of the damping material is at least 0.2 in the measuring range of 20 to 20,000 Hz, especially at least 0.5 in the range of 250 to 5000 Hz. A process for producing a thermally expandable molded part according to one of claims 1 to 8, characterized in that a polymer foam is coated in a first step with a hot-melt, non-reactive adhesive, the coated polymer foam in a second step in a Temperature of at least 80 ° C is compressed and then cooled in the compressed state. An acoustically damped structure comprising at least one acoustic damping material obtained by heating a thermally expandable molded article according to any one of claims 1 to 8.