WO2009071347A1

WO2009071347A1 - Method for reinforcing, damping, attenuating and/or sealing hollow components

Info

Publication number: WO2009071347A1
Application number: PCT/EP2008/059430
Authority: WO
Inventors: Helmut Endres; Karl Wesch
Original assignee: Henkel Ag & Co. Kgaa
Priority date: 2007-12-06
Filing date: 2008-07-18
Publication date: 2009-06-11
Also published as: DE102007059183A1

Abstract

The invention relates to reinforcing, insulating, attenuating and/or sealing hollow components, having internal limiting walls encasing a hollow space (2), using a thermally expanding material (5) and inert reinforcement parts (4), characterized in that one or more inert reinforcement parts and thermally expanding material that is not firmly connected to the inert reinforcement parts are incorporated next to each other into the hollow space such that the thermally expanding material is disposed between the reinforcement part(s) and the internal limiting walls and such that the thermally expanding material expands to a temperature in the range of 130 to 220°C by heating and cures, if desired. The invention further relates to an object comprising at least one hollow component, which has been stiffened, insulated, attenuated, or sealed according to such a method.

Description

"Method for reinforcement, insulation, damping and / or sealing of hollow components"

The invention relates to a method for structural reinforcement or reinforcement, insulation, damping and / or sealing of hollow components such as parts of vehicles, aircraft, ships or engineering structures such as architectural parts, beams, bridges and the like.

For many years, the automotive industry has endeavored to provide improved vehicle structures capable of absorbing or deflecting impulsive loads on the passenger compartment by, for example, using structures including the frame that houses the passenger compartment However, these metallic components undesirably increase the vehicle weight Other solutions provide for reinforcing members of complex shaped components which are joined to the vehicle frame by welding or by mechanical fasteners.

US-A-4,978,562 describes a specifically lightweight, reinforcing door beam made of a composite material consisting of a metal tube partially filled by a specific light weight polymer having a cellular structure. It is proposed to mix curable resins based on epoxy resins, vinyl ester resins, unsaturated polyester resins and polyurethane resins with the corresponding hardeners, fillers and cell-forming agents in an extruder, hardening this mixture into a core and so insert into the metal tube that the core through Frictional forces or mechanically fixed in the pipe. Alternatively, you can the polymer core of liquid or pasty polymeric material are prepared by casting and pressed into the tube.

Similarly, US-A-4,861,097 and US-A-4,901,500 specifically describe lightweight composite beams of foamed polymers and metallic structures for reinforcing vehicle doors. According to this teaching, the polymeric core part is first formed by producing a liquid or pasty reinforcing material, which is then injected or poured into a channel-like structure and then cured. Thereafter, this hardened core part is introduced into the metallic hollow body structure. Alternatively, the core may be preformed or molded by injection molding and then inserted into the cavity.

EP 1064188 A1 discloses a method for producing a hollow profile with internal stiffening, in particular for use in automobile bodies, in which a solid core material is coated with activatable material and an outer metal sheet is arranged to form a defined cavity. In this case, the cavity is completely filled by the foaming process of the activatable material. The solid core material is formed from a foamed or unfoamed metallic material or from a reinforced with metal fibers, carbon fibers or glass fibers synthetic material or by a hollow profile and the profile is supplied before the foaming of the activatable material an anticorrosion dip, wherein the corrosion inhibitor in all areas of the inner profile arrives. Subsequently, the hollow profile is fed to a drying oven and triggered in the drying oven, a reaction of the activatable material, whereby the defined predetermined cavity between the activatable material and the outer panel is filled.

EP 383 498 describes carrierless, foamable moldings for insertion in vehicle cavities and subsequent foaming. The molded parts can be produced by extrusion, with their cross section being adapted to the cross section of the cavity to be filled. In principle, there are two ways of introducing such masses into the hollow sections: In the first case, preforms are preformed, which are adapted to the cross section of the hollow profile to be reinforced. These are attached during assembly of the hollow profile to one of the two half-shells, which form the cavity. The production of the preformed parts takes place either in an injection molding or an extrusion process, wherein the contour of the parts is predetermined by the injection mold or the extrusion die. For each geometric shape of the reinforcement part, therefore, corresponding injection molds or extrusion matrices must be made. The preformed parts must be packed for transport so that they are not damaged. The removal from the packaging and the insertion into the hollow profile are done manually. This entire process is very labor-intensive and thus costly.

An alternative to this is the production of granules of the thermally expandable material and its shipping in granular form to the site. There, the granules are melted and pressed by an extruder into the cavity to be reinforced. This requires appropriate extruder facilities at the site and this trained operators.

With regard to the known prior art, the inventors have set themselves the task of providing a method for reinforcement, insulation, damping and / or sealing of hollow components available, in which it is not necessary, reinforcing elements in prefabricated form or with a to produce the respective hollow component adapted cross-section. Furthermore, the required amount of thermally expandable material should be kept as low as possible.

The present invention relates, in a first aspect, to a method for reinforcing, damping, damping and / or sealing hollow components having inner boundary walls enclosing a cavity, using a thermally expanding material and inert reinforcement parts, characterized in that one or more inert ones reinforcement parts and thermally expandable material that is not fixedly connected to the inert reinforcing members, side by side so inserted into the cavity that the thermally expandable material between the reinforcing member (s) and the inner boundary walls is disposed, and the thermally expandable material by heating expanded to a temperature in the range of 130 to 220 ⁰ C and cures if desired. In the following description, instead of the term "thermally expandable material", the terms "thermally expandable material" or "reactive structural material" will also be used Preferably, this composition hardens during or after the thermal expansion.

"Inert reinforcing parts" are understood to mean parts of a material which does not significantly deform at temperatures of up to 220 ^° C. Examples include parts made of ceramic (including glass ceramic) or of metals such as steel or, for weight reasons, aluminum in particular Reinforcing parts made of plastics suitable as "inert reinforcing parts", provided that the plastic meets the conditions mentioned. An example of this is polyamide. Parts made of ceramic or plastic, in particular polyamide, may be reinforced with fibers. These can be selected, for example, from aramid fibers, carbon fibers, metal fibers-for example from aluminum, glass fibers, polyamide fibers, polyethylene fibers or polyester fibers.

To save weight, it is preferred that the inert reinforcement parts have at least one inner cavity and / or consist of a foam structure. Preference is given to using those reinforcing parts which, with the inclusion of the cavities, have an apparent specific gravity in the range from 0.1 to 0.8, preferably in the range from 0.2 to 0.5, g / cm ³ .

To reinforce the cavity of the hollow component after expansion of the thermally expandable material must be at least in one direction in a cross-sectional area of the hollow component completely filled with the expanded thermally expandable material and the reinforcing member or the reinforcing members be. The size and number of reinforcing parts and the amount of thermally expandable material and the degree of expansion of the thermally expandable material must be coordinated accordingly.

A possible embodiment of this invention is that the thermally expandable material is in the form of parts in which a dimension corresponds to at least 90% of the length of that side of the inert filler part adjacent to which the part of thermally expandable material is placed. For example, these may have the form of cuboids, in particular of bars, plates, bands or strips.

Another possible embodiment is that the thermally expandable material is introduced as an arrangement of large and small balls, wherein the large balls have an average outer diameter in the range of 2 to 20 mm and the small balls are selected from first small balls and second small Spheres or a mixture thereof, wherein the first small balls have an average outer diameter which differs by not more than 20% of the diameter of a ball which fits exactly into a Tetreaderlücke a closest packing of the large balls and wherein the second small balls average outer diameter that deviates by no more than 20% from the diameter of a sphere that fits exactly into an octahedral gap of a closest packing of the large balls, and wherein either the large balls of a thermally expandable material and the small balls of a thermally inert Material exist, o that the small balls of a thermally expandable material and the large balls made of a thermally inert material, wherein the thermally expandable material is selected so that when heated from 20 ⁰ C to a temperature in the range of 130 to 220 ⁰ C. 5 to 200% expands and solidifies, and wherein the thermally inert material is defined as a material that does not soften or melt at a temperature of not more than 230 ⁰ C. The concept of this embodiment of the present invention is based on the theoretical model of a densest sphere of large spheres known to contain so-called tetrahedral voids and so-called octahedral voids. A tetrahedral gap is equally bounded by 4 spheres, an octahedral gap of 6 spheres. In the ideal borderline case, a densest sphere packing contains just as many octahedral voids and twice as many tetrahedral voids as spheres. The diameter of spheres that fit exactly into an octahedral or tetrahedral gap depends on the diameter of the spheres that make up the sphere packing through a simple geometric relationship.

In its general form, the present invention leaves open whether preferably the large balls or preferably the small balls are made of a thermally expandable material. In practice, since the material for the thermally non-expandable balls can be chosen to be cheaper than the thermally expandable material, it is preferred for cost reasons that the large balls be made of a thermally inert and the small balls of a thermally expandable material consist.

In the theoretical ideal case of a densest sphere packing, an optimal filling of the total volume would be achieved if the arrangement of large and small balls contains twice as many first small balls as large balls and as many second small balls as large balls. In order to take into account the practical situation of a non-ideal ball packing, it is preferred in the context of the present invention that the number of large and small balls is in each case not more than 50%, preferably not more than 30% and in particular not more than 20% deviates from at least one of the following conditions:

a) The arrangement contains twice as many first small balls as large balls, b) the arrangement contains as many second small balls as large balls. Preferably, the composition of the array of large and small spheres does not deviate by more than 50%, preferably not more than 30%, and in particular not more than 20%, from the ideal condition that the assembly comprises both twice as many first small spheres as also contains as many second small balls as big balls.

The number of large and small balls that are used to make the arrangement, can be determined not only by direct counting, but in known mass of the individual balls by weighing.

In a further embodiment of the present invention, the thermally expandable material is introduced in the form of an array of balls selected from hollow spheres having an inner diameter in the range of 0.5 to 10 mm and a wall thickness in the range of 0.01 to 2 mm and from Balls of a foam having a diameter in the range of 0.5 to 12 mm, which is solid at a temperature below 220 ^° C., the balls being coated on the outside with a thermally expandable material.

In this embodiment, the balls are preferably coated with the thermally expandable material so that the thickness of the thermally expandable material is 10 to 50% of the outer diameter of the uncoated balls. The coating thickness should be selected the greater the less the thermally expandable material expands when heated. Expansion rate and thickness of the thermally expandable material should be coordinated so that assuming a densest sphere packing, the gaps between the balls when foaming the thermally expandable material can be at least completely filled. Since the arrangement of balls in practice will differ from the densest ball packing, so that the proportion of the volume of the spaces between the balls in the total volume of the arrangement of the balls is greater than in the theoretical limit of the densest ball packing, layer thickness and rate of expansion of the thermally expanding Baren material to be matched to one another so that at least 1, 2-fold, preferably at least 1.5 times, and in particular at least twice the void volume of a dense spherical packing can be filled during foaming.

For the purposes of this invention, the term "balls" is intended to encompass not only balls in the strict geometric sense, but generally ball-like structures such as, for example, drawn or compressed balls, egg-shaped structures or spherical structures with a bulged or dented surface. For example, Kugei-shaped structures of metal foam or ceramic, such as expanded clay, generally do not have the shape of an exact geometrical sphere , which are summarized here by the term "balls", have a longest and a shortest diameter, which do not differ by more than 20%.

If this is referred to as a "mean (outer) diameter", then this formulation should take into account the fact that deviations in diameter may occur in the production of the approximately spherical bodies For example, it may be possible that the actual diameters of the individual balls can deviate by up to 20% from the mean value.

An "arrangement of balls" is understood to mean a three-dimensional arrangement of 10 or more balls, with at least 90% of the balls touching three or more adjacent balls, for example a ball of balls in a container with fixed or yielding limitations For example, it can be an arrangement of balls in a hollow component to be reinforced, the balls being held together by the inner walls of the hollow component and boundary surfaces of the inert reinforcement parts. Also, a hose filled with balls or a bag filled with balls, for example a plastic bag.

The still present after the expansion of the thermally expandable material balls of non-thermally expandable material to be able to absorb pressure, shock or torsional forces without deforming noticeable. In the case of hollow balls therefore wall material, wall thickness and inner diameter must be coordinated accordingly. The smaller the inner diameter, the lower the wall thickness can be. For more easily deformable material, greater wall thicknesses are required than for less easily deformable material. For example, these spheres may constitute hollow spheres and consist of a material which is selected from glass, ceramic, metal or of a plastic that does not deform significantly upon heating to a temperature up to 220 ⁰ C. For example, polyamide is suitable for this purpose.

As an alternative to hollow balls, these balls can also consist of a foam. For example, this may be a metal foam, for reasons of weight, in particular of aluminum, magnesium or alloys which consist of at least 50 wt .-% of at least one of these metal. The foam may also be a ceramic foam such as expanded clay.

The arrangement of balls should have the lowest possible specific gravity. Therefore, the material of the balls is preferably chosen so and in the case of hollow spheres their outer diameter and wall thickness coordinated so that a jarred arrangement of uncoated balls or balls of a non-thermally expandable material has a bulk density in the range of 0.1 to 0.8 , preferably 0.2 to 0.5 g / cm ³ .

Whichever of the above two types of ball arrangement is used, the balls may be provided in the form of a loose fill in the space (s) provided between several inert reinforcement parts or between inert reinforcement parts and inner boundary parts. bring tioning walls of the cavity to be reinforced. For example, the ball fill can be generated by mechanically introducing the balls into the hollow component to be reinforced, for example, blowing in or dropping under the action of gravity.

In a further preferred embodiment, the array of balls consists of a preselected amount located in a flexible container in the manner of a bag, the material of the container being chosen to be heated to a temperature in the range of 130 to 220 ⁰ C softens or melts. To reinforce a cavity, two or more such ball-filled bags are placed in the interstices to be filled. Shape and size of the bag and the amount of balls are preferably matched to the shape and size of the space to be filled. For example, in reinforcing elongate hollow members using elongate inert reinforcing members, the bag may be in the form of a tube.

The ball-filled bag can be placed, for example, in a prefabricated, but at least one end open hollow component in or put into it. In the simplest case, it fixes itself by frictional forces in the cavity itself. However, holding elements such as projections or pins can also be provided in the cavity on which the ball-filled bag can be placed.

If, as usual, the hollow component is produced by connecting two preformed half-shells together, the ball-filled small bag can be attached to one of the half-shell inner walls before the two half-shells are connected. This can be done by hooking the bag into an intended mechanical fastener such as a hook or by means of a clip in a hole or by sticking the bag to the wall of a half-shell. The material of the bag should soften at the expansion temperature at least so far that the expansion of the thermally expandable mass is not hindered. When choosing the material that makes up the container for the mixture of large and small balls, make sure that it does not affect the adhesion of the thermally expanded mass to the inner wall of the filled hollow component. This can be ensured, in particular, by mixing the material of the container with the thermally expanding compound, dissolving in and / or reacting with it.

Furthermore, in practice there is the problem that a predetermined arrangement of large and small balls segregates when jogging. This can be the case during transport, for example. If the mixture of large and small balls is enclosed in a container in such a way that the balls can move as little as possible against each other, segregation is severely restricted. This can be achieved in particular in that the material of the container is shrinkable, for example by heating, and after filling the container with the mixture of large and small balls shrunk. The mixture is then pressed together by the shrunken container material, so that the mobility of the balls is further limited against each other.

Another embodiment of the present invention is that the thermally expandable material is introduced as granules into at least one space between the reinforcing part (s) and the inner boundary walls of the cavity. Or the thermally expandable material is introduced as a pumpable mass in at least one space between the (the) reinforcing member (s) and the inner boundary walls of the cavity.

Since the inert material can be chosen cheaper than the thermally expandable material, it is preferred that the cavity to be reinforced as far as possible is filled by the inert material. Therefore one agrees preferential wise size and number of reinforcing parts and the amount of thermally expandable material and the degree of expansion of the thermally expandable material from each other so that the volume of the cavity, which is filled by the expanded thermally expandable material and the reinforcing member or the reinforcing members, at least 50, preferably at least 70% by volume is filled by the reinforcing member or the reinforcing members.

Depending on the shape of the cavity, both the reinforcing members and the pieces of thermally expandable material or bags containing balls of thermally expandable material may be shaped differently. For example, the reinforcing members may be round or polyhedral closed or partially open hollow bodies or tubulars of round or polygonal cross-section. If the reinforcing members are made of a foam structure, they may be round or polyhedral bodies or columns of round or polygonal cross-section. Especially for stiffening elongated cavities, it is preferable that both the reinforcing members and the pieces of thermally expandable material are elongate, i. H. have a longitudinal axis which is at least 1.5 times as long as the next shorter axis. For example, reinforcing members and pieces of thermally expandable material may be used whose longest axis is at least 5 times as long as the next shorter axis. The same applies if the thermally expandable material is introduced in one of the other ways described: In this case, it is ensured that the corresponding elongated spaces between inert reinforcement part and inner boundary wall of the cavity to be reinforced are filled. For example, this can be done by introducing the thermally expandable material into correspondingly shaped bags in the interstices.

The inert molded part preferably has projecting walls or ribs which point in the direction of the inner walls of the cavity and laterally delimit the intermediate space to be filled with the thermally expandable material. This allows the thermally expandable material better on the To fill in the space provided. At the same time, these walls or ribs inhibit lateral expansion of the thermally expandable mass as it expands so that this mass is preferably trapped between the inert reinforcement member and interior walls of the cavity. Figures 1 and 2 show this schematically.

The thermally expandable and preferably curable material is preferably selected so that it expands upon heating of 20 ⁰ C to a temperature in the range of 130 to 220 ⁰ C by 5 to 200%, preferably by 10 to 100%. Such materials are known in the art and are described below by way of example.

Preferably, the expandable mass contains at least the following components: a) at least one reactive prepolymer, b) at least one (chemical or physical) latent blowing agent.

Depending on the chemical nature of the prepolymer, the mass may additionally contain: c) at least one latent hardener for the reactive prepolymer.

In this case, "latent" means that the desired reaction of the respective component does not occur below 80 ^° C., but in the temperature range from 130 to 220 ^° C.

In particular, the thermally expandable composition contains at least: a) a resin which crosslinks with itself or with other constituents of the composition (for example an optionally added hardener) at temperatures in the range from 130 to 220 ^° C. (also referred to below as "binder"), b) a blowing agent which reacts at a temperature in the range of 130 to 220 ⁰ C under increase in volume or evolution of gas and thereby increases the volume of the mass at least in the extent specified above. In a particularly preferred embodiment, the compositions for the thermally curable structural material additionally contain fibers based on aramide fibers, carbon fibers, metal fibers - for example aluminum, glass fibers, polyamide fibers, polyethylene fibers or polyester fibers, these fibers preferably being pulp fibers or staple fibers have a fiber length between 0.5 and 6 mm and a diameter of 5 to 20 microns. Particularly preferred are polyamide fibers of the type of aramid fiber or polyester fibers.

In the following, some examples of a suitable thermally expandable composition, also referred to below as "structural material", are given:

The curable resin a) may for example be selected from: polyurethanes with free or blocked isocyanate groups, unsaturated polyester / styrene systems, polyester / polyol mixtures, polymercaptans, siloxane-functional reactive resins or rubbers, benzoxazine-based resins and resins based on of reactive epoxide groups.

Further suitable polymeric base binders ("resins") for the thermally expandable structural material are, for example, ethylene-vinyl acetate copolymers (EVA), copolymers of ethylene with (meth) acrylate esters, which may also contain copolymerized (meth) acrylic acid in copolymerized form, random or block copolymers of styrene with butadiene or isoprene or their hydrogenation products, the latter also being able to be triblock copolymers of the SBS, SIS or their hydrogenation products SEBS or SEPS In addition, the binders may also contain crosslinkers, adhesion promoters, tackifiers, plasticizers and other auxiliaries and additives such as B. low molecular weight oligomers.

An alternative binder system ("resin") for the reactive expandable structural material based on epoxy resins and hard materials is described below. ben, as disclosed, for example, in WO 00/52086 or WO 2003/054069 and WO 2004/065485:

As epoxy resins are a variety of polyepoxides having at least 2 1, 2-epoxy groups per molecule. The epoxide equivalent of these polyepoxides may vary between 150 and 50,000, preferably between 170 and 5,000. The polyepoxides may in principle be saturated, unsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic or heterocyclic polyepoxide compounds. Examples of suitable polyepoxides include the polyglycidyl ethers prepared by reaction of epichlorohydrin or epibromohydrin with a polyphenol in the presence of alkali. Suitable polyphenols for this purpose are, for example, resorcinol, pyrocatechol, hydroquinone, bisphenol A (bis (4-hydroxy-phenyl) -2,2-propane)), bisphenol F (bis (4-hydroxyphenyl) methane), bis (4 -hydroxy-phenyl) -1,1-isobutane, 4,4'-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1,1-ethane, 1,5-hydroxy-naphthalene. Other suitable polyphenols as a basis for the polyglycidyl ethers are the known condensation products of phenol and formaldehyde or acetaldehyde type of novolac resins.

Further polyepoxides are polyglycidyl esters of polycarboxylic acids, for example reactions of glycidol or epichlorohydrin with aliphatic or aromatic polycarboxylic acids such as oxalic acid, succinic acid, glutaric acid, terephthalic acid or dinner fatty acid.

Other epoxides are derived from the epoxidation products of olefinically unsaturated cycloaliphatic compounds or of native oils and fats.

Very particular preference is given to the epoxy resins which are derived by reaction of bisphenol A or bisphenol F and epichlorohydrin, the liquid epoxy resins preferably being based on bisphenol A and having a sufficiently low molecular weight. The room temperature liquid epoxy resins typically have an epoxide equivalent weight of 150 to about 480, more preferably an epoxide equivalent weight range of 182 to 350. Flexibilizing agents which can be used are flexibilizing epoxy resins, such as the known adducts of carboxyl-terminated butadiene-acrylonitrile copolymers (CTBN) and liquid epoxy resins based on the diglycidyl ether of bisphenol A. Concrete examples are the reaction products of Hycar CTBN 1300 X8, 1300 X13 or 1300 X15 from BF Goodrich with liquid epoxy resins. Furthermore, the reaction products of amino-terminated polyalkylene glycols (Jeffamine) can be used with an excess of liquid polyepoxides. In principle, it is also possible to use reaction products of mercapto-functional prepolymers or liquid Thiokol polymers with an excess of polyepoxides as flexibilizing epoxy resins according to the invention. However, very particularly preferred are the reaction products of polymeric fatty acids, in particular dimer fatty acid with epichlorohydrin, glycidol or in particular diglycidyl ether of bisphenol A (DGBA). Furthermore, the copolymers of acrylonitrile with butadiene and / or isoprene and optionally (meth) acrylic acid having an acrylonitrile content between 10 and 50 wt .-%, preferably between 20 and 40 wt.% And a (meth) acrylic acid content between 0, 0 and 1 wt.%, Preferably between 0.0 and 0.1 wt.% As a flexibilizer. It is also possible to use mixtures of the abovementioned flexibilizers.

The reactive structural material may contain reactive diluents to set a desired viscosity for, for example, an extrusion process. Reactive diluents for the purposes of this invention are epoxide-containing, low-viscosity substances (glycidyl ethers or glycidyl esters) having an aliphatic or aromatic structure. These reactive diluents serve on the one hand to reduce the viscosity of the binder system above the softening point, on the other hand they control the pre-gelation process by injection molding. Typical examples of reactive diluents for use in accordance with the invention are mono-, di- or triglycidyl ethers of C 1 -C ₄ -monoalcohols or alkylphenols and the monoglycidyl ethers of cashew nut shell oil, diglycidyl ethers of ethylene glycol, diethylene glycol, ethylene glycol, tetraethylene glycol, 1, 2-propylene glycols, 1, 4 Butylene glycols, 1, 5-pentanediol, 1, 6-hexanediol, cyclohexanedimethanol, triglycidyl ether of tri-methylolpropans and the glycidyl esters of Ce- to C ₂₄ - carboxylic acids or mixtures thereof.

Since the curable structural material is preferably one-component and should be curable in the heat, it also contains a latent curing agent and / or additionally one or more accelerators.

As thermally activatable or latent hardeners for an epoxy resin binder system, guanidines, substituted guanidines, substituted ureas, melamine resins, guanamine derivatives, cyclic tertiary amines, aromatic amines and / or mixtures thereof can be used. The hardeners may be involved in the curing reaction both stoichiometrically, but they may also be catalytically active. Examples of substituted guanidines are methyl guanidine, dimethylguanidine, trimethylguanidine, tetramethylguanidine, methylisobiguanidine, dimethylisobiguanidine, tetramethylisobiguanidine, hexamethylisobiguanidine, hepamethylisobiguanidine and, in particular, cyanoguanidine (dicyandiamide). Representatives of suitable guanamine derivatives include alkylated benzoguanamine resins, benzoguanamine resins or methoxymethylethoxymethylbenzoguanamine. Of course, for the one-component, thermosetting compositions, the selection criterion is the low solubility of these substances at room temperature in the resin system, so that solid, finely ground hardeners are preferred, in particular dicyandiamide is suitable. This ensures good storage stability of the composition.

In addition to or instead of the aforementioned hardeners, catalytically active substituted ureas can be used. These are in particular the p-chlorophenyl-N, N-dimethylurea (monuron), 3-phenyl-1, 1-di-methylurea (Fenuron) or 3,4-dichlorophenyl-N, N-dimethylurea (diuron). In principle, it is also possible to use catalytically active tertiary acrylic or alkyl amines, such as, for example, the benzyldimethylamine, ths (dimethylamino) phenol, piperidine or piperidine derivatives, but these have in many cases a too high solubility in the binder system, so that here no useful storage stability of the one-component system is achieved. Furthermore, various, preferably solid, imidazole derivatives can be used as catalytically active accelerators. Representative examples include 2-ethyl-2-methylimidazole, N-butylimidazole, benzimidazole and N-C1 to C12 alkylimidazoles or N-arylimidazoles, Thazindehvate and imidazole / triazine compounds (eg C11-Z-azines). It is also possible to use combinations of hardener and accelerator in the form of so-called accelerated dicyandiamides in finely ground form. As a result, the separate addition of catalytically active accelerators to the epoxy curing system is sometimes unnecessary.

For particularly reactive systems, it is also possible to use finely ground powdery curing accelerators based on adducts of amines with epoxy resins; these adducts have tertiary amino groups and epoxy groups. These latent powdery accelerators can be used in combination with the aforementioned latent hardeners and / or accelerators.

Furthermore, the reactive and thermally expandable structural materials may contain at least one finely divided thermoplastic polymer powder. These thermoplastic polymer powders may in principle be selected from a large number of finely divided polymer powders, examples being vinyl acetate homopolymer, vinyl acetate copolymer, ethylene vinyl acetate copolymer, vinyl chloride homopolymer (PVC) or copolymers of vinyl chloride with vinyl acetate and / or (meth) acrylates, Styrene homopolymers or copolymers, (meth) acrylate homo- or copolymers or polyvinyl butyral. Particularly preferred thermoplastic polymers contain functional groups such as carboxyl groups, carboxylic anhydride groups or imidazole groups and have a core / shell structure, the shell of these polymers having a low swelling behavior at room temperature compared to plasticizers or reactive diluents. In the pre-gelling reaction during extrusion of the reactive structural material, these core / shell polymers swell very rapidly and, upon cooling the extruded mass, immediately cause a tack-free surface of the expandable binder. demittelschicht. These polymer powders should have an average particle size of less than 1 mm, preferably less than 350 μm and most preferably less than 100 μm.

In general, the reactive structural material further contains per se known fillers such as the various milled or precipitated chalks, carbon black, calcium magnesium carbonates, barite and in particular silicatic fillers of the type of aluminum-magnesium-calcium silicate, z. B. wollastonite, chlorite.

If the thermally expandable, thermosetting structural material is used to produce specific light structures, it preferably contains, in addition to the aforementioned "normal" fillers, so-called light fillers which are selected from the group of hollow metal spheres, such as e.g. Hollow hollow spheres, glass hollow spheres, fly ash (Fillite), plastic hollow spheres based on phenolic resins, epoxy resins or polyesters, expanded hollow microspheres with wall material of (meth) acrylic acid ester copolymers, poly-styrene, styrene (meth) acrylate copolymers and in particular polyvinylidene chloride and copolymers of vinylidene chloride with acrylonitrile and / or (meth) acrylic esters, ceramic hollow spheres or organic light fillers of natural origin such as ground nutshells, for example the shells of cashew nuts, coconuts or peanut shells and cork powder or coke powder. Particular preference is given to such lightweight fillers based on hollow microspheres, which ensure a high compressive strength of the foamed and cured structural material.

Although suitable as blowing agents are in principle all known blowing agents such. As "chemical blowing agents" released by decomposition gases or "physical blowing agent", ie expanding hollow spheres. Examples of the former blowing agents are azobisisobutyronitrile, azodicarbonamide, di-nitroso-pentamethylenetetramine, 4,4'-oxybis (benzenesulfonic acid) hydrazide, diphenylsulfone-3,3'-disulfonazole, benzene-1,3-disulfohydrazide, p-toluenesulfonyl semicarbazide , Especially However, the expandable Kunststoffmikrohohlkugeln based on polyvinylidene chloride copolymers or acrylonitrile / (meth) acrylate copolymers are preferred, these are available for example under the name "Dualite®" or "Expancel®" from the companies Pierce & Stevens and Casco Nobel commercially ,

Furthermore, the reactive structural materials common other auxiliaries and additives such. As plasticizers, rheology aids, wetting agents, adhesion promoters, anti-aging agents, stabilizers and / or color pigments.

In order to be able to fulfill the task of stiffening the space between the cavity profile and the inert reinforcement part after curing, it is expedient for the structural material used to have an E-modulus of at least 300 MPa. As known to those skilled in the art, this can be adjusted by the type and amount of hardeners and accelerators.

For example, thermally curable structural materials are suitable which form ductile structural foams after curing and which are described in German patent application 102006050697.9, which has not been pre-published. These have a ductile behavior in the temperature range from -20 to +80 ⁰ C, with essentially no lowering of the force level. This allows for improved finite element analysis (FEA) calculations by providing a constant force level across the deformation range. This allows new applications, since under load a defined deformation of the structural foam takes place, instead of a brittle bursting of the foams at low deformations.

The corresponding curable structural material contains: at least one epoxy resin, at least one phenolic compound, at least one polyether amine, at least one blowing agent, at least one hardener and at least one filler.

As epoxy resins are a variety of polyepoxides having at least 2 1, 2-epoxy groups per molecule and have been described in detail above.

Optionally, the binder compositions may contain reactive diluents to adjust the flow behavior, as also described in more detail above.

Preferred phenolic compounds are solid at room temperature (ie, in a temperature range between 18 ^° C. and 25 ^° C., preferably 22 ^° C.) and have a molecular weight (Mn) of between 2,800 and 9,000. Preferably, the phenolic compounds are difunctional with respect to the phenolic ones Groups, ie they have a content of phenolic hydroxyl groups between 1 400 and 2 500 mmol / kg. In principle, all phenol compounds which fulfill the abovementioned criteria are suitable, but very particular preference is given to reaction products of difunctional epoxy compounds with bisphenol A in stoichiometric excess.

Preferred polyetheramines are amino-terminated polyalkylene glycols, in particular the difunctional amino-terminated polypropylene glycols, polyethylene glycols or copolymers of propylene glycol and ethylene glycol. These are also known under the name "Jeffamine" (trade name of Huntsman). Also suitable are the difunctional amino-terminated polyoxytetramethylene glycols, also called polyTHF. The molecular weight range (Mn) of the preferably difunctional polyetheramines (based on the primary amino groups) is between 900 and 4,000, preferably between 1,500 and 2,500.

Suitable blowing agents are in principle all known blowing agents, as described in more detail above. The hardeners used are thermally activatable or latent hardeners for the epoxy resin binder system, which have also been described in greater detail above.

The thermally curable compositions which can be used according to the invention can furthermore comprise finely divided thermoplastic copolymers, as described in greater detail above.

In general, these thermally curable compositions further contain per se known fillers such as the various milled or precipitated chalks, carbon black, calcium magnesium carbonates, barite and in particular silicatic fillers of the type of aluminum-magnesium-calcium silicate, z. B. wollastonite, chlorite. Preference is given to using mica-containing fillers, with very particular preference here being given to a so-called two-component filler of muscovite mica and quartz with a low heavy metal content.

Furthermore, the curable structural materials to be used according to the invention can be customary further auxiliaries and additives, such as, for example, As plasticizers, reactive diluents, rheology aids, wetting agents, adhesion promoters, anti-aging agents, stabilizers and / or color pigments. Depending on the requirement profile in terms of processing properties, the flexibility, the required stiffening effect and the adhesive bond to the substrates, the proportions of the individual components can vary within relatively wide limits. Typical ranges for the essential components are:

solid epoxy resin 2 to 65% by weight,

Phenol compound 1 to 30% by weight, preferably 5 to 10% by weight

Polyetheramine 0.5 to 15% by weight, preferably 2 to 10% by weight

Blowing agent 0.1 to 5 wt .-%,

Hardener and accelerator 1, 5 to 5 wt .-%,

Mica-based filler 0 to 40% by weight, preferably 1 to 30% by weight Other fillers 5 to 20% by weight

Reactive diluents 0 to 15% by weight, preferably 0 to 10% by weight

Ethylene-vinyl acetate copolymer 0 to 10% by weight, preferably 1 to 10% by weight

Fibers 0 to 30% by weight, preferably 0 to 10% by weight

Pigments 0 to 1 wt .-%, wherein the sum of the total components 100 wt .-% results.

As a reactive structural material can also be used:

According to WO 00/37554, compositions

A) a copolymer having at least one glass transition temperature of

-30 ⁰ C or lower and epoxide-reactive groups or a reaction product of this copolymer with a polyepoxide and

B) a reaction product of a polyurethane prepolymer and a polyphenol or aminophenol and

C) contain at least one epoxy resin.

More detailed information can be found in WO00 / 37554.

According to WO00 / 20483 compositions comprising:

A) a copolymer having at least a glass transition temperature of - 30 ⁰ C or lower and epoxide-reactive groups

B) a reaction product preparable by reacting a carboxylic anhydride or dianhydride with a di- or polyamine and a polyphenol or aminophenol

C) at least one epoxy resin.

More detailed information can be found in WO00 / 20483.

In particular, those expandable materials are preferred which are compatible with the inner walls (eg made of steel or another metal or plastic) of the cavity structure to be reinforced and with the walls of the inert reinforcement. kungsteile can bond so that the impact forces can be introduced by the adhesion frictionally in the reinforcing structure optimally.

The thermally expandable material may already be formed into the desired pieces at the place of its manufacture, for example by casting into a suitable mold or by extrusion into a strand and cutting the extruded strand. However, this has the disadvantage that the preformed pieces have to be packed, shipped and removed at the point of application of the package. Therefore, in one embodiment, it is preferable to proceed by extruding and shipping the thermally expandable material as a strand and cutting it into pieces of predetermined length only prior to insertion into the cavity at the point of use. For example, this can be done by rolling up the extruded strand into a roll, unwinding at the point of use and cutting into pieces of predetermined length. With a gripping device, for example a robot arm, the cut pieces can be gripped and inserted into the hollow component. The reinforcing members of inert material are preferably provided at the point of use so that they can also be gripped by a robotic arm and inserted into the cavity.

Alternatively, when using thermally expandable material in spherical form that you can fill them in the bags described above, whose size and shape is matched to the spaces to be filled.

Direct contact of the inert reinforcement parts with the inner walls of the hollow component should be avoided. Therefore, the reinforcing members and the pieces of thermally expandable material are disposed in the cavity such that a portion of a thermally expandable material comes to rest between the inner wall of the cavity and a reinforcing member. In this case, a single inert reinforcement part can be used, which fills the cavity to be reinforced at least in a cross-sectional plane by more than 50% and which is at least approximately positioned in the middle of the cavity, while at least two, but preferably a plurality of pieces of thermally expandable material are introduced into the remaining space between inner walls of the cavity and the reinforcement part. However, it is also possible to provide two or more inert reinforcing parts, which are introduced side by side into the cavity, wherein pieces of thermally expandable material are respectively arranged between the individual reinforcing parts and between the reinforcing parts and the inner wall of the cavity. This can be done automatically by a suitably programmed robot.

Analogously, in the aforementioned alternative embodiments, the bags corresponding to the above are classified, which contain the thermally expandable material. Or one brings this loosely into the corresponding spaces, to better limit the above-mentioned projecting walls or ribs on the inert reinforcement parts can be helpful.

It is preferably provided that in the cavity of the hollow component holding elements provided on soft the reinforcing member or the reinforcing members and the pieces of the bags or set up with a thermally expandable material or to which the reinforcing member or the reinforcing members and the pieces be ajar from a thermally expandable material. Such holding elements may be, for example, nets, screens or preferably perforated plates. Such holding elements can also serve to fix in a spherical or granular form or as a pumpable mass introduced thermally expandable material.

In a preferred embodiment of the present invention may be provided to prefabricate the desired spatial arrangement of the parts of a thermally expanding material and the inert reinforcing parts and insert in the prefabricated state in the hollow profile to be reinforced. For this prefabrication can be provided, for example, holding plates, in which the parts of the thermally expandable part and the inert reinforcing parts are inserted and fixed in the desired arrangement. These holding plates can also have the form of a lattice structure. The retaining plates can be made of a material which can also serve as material for the reinforcing parts, as described above. Preferably, the holding plates fastening elements such as clips or glued or weldable flanges, so that the entire assembly of retaining plate and the parts of the thermally expanding material and the inert reinforcing parts are mounted on the one half shell during assembly of a hollow profile of two half-shells can before it is connected to the other half-shell.

Accordingly, an embodiment of the method according to the invention is that one arranges parts of thermally expandable material and inert reinforcing parts side by side on a holding device and uses this holding device with the arrangement of the parts of thermally expandable material and the inert reinforcing parts in the hollow component. A corresponding arrangement of parts of a thermally expandable material and of inert reinforcing parts, which are fixed by a holding device relative to each other, also belongs to the scope of the present invention.

Preferably, one arranges the reinforcing members and the pieces or bags of thermally expandable material so that along the inner walls of the hollow member a tipping gap of a width of about 1 to about 10 mm, preferably from about 2 to about 4 mm remains. This flood gap ensures that the various process fluids with which the body shell is treated can wet all parts of the insides of the cavity walls. The flood gap closes only during the thermal expansion of the thermally expandable and curable material, whereby the purpose of filling the reinforcement, insulation, damping and / or sealing of the hollow components is achieved.

Finally, the present invention relates to an article which contains at least one hollow component which has been stiffened, insulated, damped or sealed by the method according to the invention. For example, this item may be a land vehicle such as a rail vehicle. vehicle or a motor vehicle. However, according to the invention reinforced hollow components can also be installed in aircraft, ships, engineering structures such as architectural parts, carriers, bridge parts and the like. This object may in particular be a vehicle which contains a hollow component equipped in this way. For this example, hollow beams such as the A-, B- or C-pillar, sills or similar hollow components come into consideration.

Description of the pictures:

The figures illustrate the present invention by way of example, without limiting it thereto.

Each of the figures schematically shows a cross section through a hollow component, such as one of the "pillars" of a motor vehicle. This hollow member is created by connecting two half shells 1 a and 1 b to the flanges between them and includes a cavity 2 a. In this cavity, a, also shown in cross section, inert reinforcing member 3 is used, which in turn surrounds a cavity 8. This is shown here empty, but may be in other embodiments of the present invention by reinforcing elements such as partitions, ribs or struts traversed or filled with a foam structure.

The inert reinforcing member 3 has in this example a total of four projecting walls or ribs 4, each narrowing in pairs gaps 9, which are to receive the thermally expandable material. In Fig. 1, the thermally expandable material is used as a compact piece 5 in the space 9 between the reinforcement part 3 and the inner walls of the half-shells 1 a and 1 b.

Fig. 2 shows two alternative embodiments, the thermally expandable mass as balls in the space 9 between reinforcement part 3 and the inner wall of a half-shell 1 a and 1 b to introduce. Here is schematic here a variant with approximately equal sized balls shown, which consist of an inert core and a shell of thermally expandable material, as has been described in detail as an embodiment above. In the upper space 9, these balls are enclosed in a bag 7, while they are introduced in the lower space 9 as a loose ball bed.

Claims

claims

A method for reinforcing, damping, damping and / or sealing of hollow components having a cavity enclosing inner boundary walls, using a thermally expanding material and inert reinforcing members, characterized in that one or more inert reinforcing members and thermally expandable material, the is not fixedly connected to the inert reinforcing members, side by side into the cavity so that the thermally expandable material between the reinforcing member (s) and the inner boundary walls is disposed, and the thermally expandable material by heating to a temperature in the range of 130 to 220 ⁰ C expands and cures if desired.

2. The method according to claim 1, characterized in that the thermally expandable material is in the form of elongated parts in which a dimension corresponds to at least 90% of the length of that side of the inert filling member, adjacent to which the part of thermally expandable material is arranged.

3. The method according to claim 1, characterized in that the thermally expandable material is introduced as an arrangement of large and small balls, wherein the large balls have an average outer diameter in the range of 2 to 20 mm and the small balls are selected from first small balls and second small spheres, or a mixture thereof, wherein the first small spheres have an average outer diameter which deviates by no more than 20% from the diameter of a sphere which fits exactly into a tetanoid gap of a closest packing of the large spheres and wherein the second small spheres have an average outer diameter of not more than 20% deviates from the diameter of a sphere that fits exactly into an octahedral gap of a closest packing of the large balls, and where either the large balls of a thermally expandable material and the small balls made of a thermally inert material, or that the small balls of a thermally expandable material and the large balls of a thermally inert material, wherein the thermally expandable material is selected so that when heated from 20 ⁰ C to a temperature in the range of 130 to 220 ⁰ C by 5 to 200% expands and solidified therein, and wherein the thermally inert material is defined as a material which does not soften or melt at a temperature of not more than 230 ⁰ C.

4. The method according to claim 3, characterized in that in the arrangement of large and small balls, the number of large and small balls differs by not more than 20% of at least one of the following conditions: a) the arrangement contains twice as many first small balls like big balls, b) the arrangement contains as many second small balls as big balls.

5. The method according to claim 1, characterized in that the thermally expandable material is present as an array of balls selected from hollow spheres having an inner diameter in the range of 0.5 to 10 mm and a wall thickness in the range of 0.01 to 2 mm and from balls of a foam having a diameter in the range of 0.5 to 12 mm, which is solid at a temperature below 220 ^° C., the balls being coated on the outside with a thermally expandable material.

6. The method according to one or more of claims 3 to 5, characterized in that the arrangement of balls it consists of a preselected amount of balls, which is located in a container, wherein the Material of the container is selected so that it softens or melts when heated to a temperature in the range of 130 to 220 ⁰ C.

7. The method according to claim 6, characterized in that the material of the container is shrinkable and shrunk after filling of the container with the arrangement of balls.

8. The method according to claim 1, characterized in that the thermally expandable material is introduced as granules in at least one intermediate space between the (the) reinforcing member (s) and the inner boundary walls of the cavity.

9. The method according to claim 1, characterized in that the thermally expandable material is introduced as a pumpable mass in at least one space between the (the) reinforcing member (s) and the inner boundary walls of the cavity.

10. The method according to one or more of claims 1 to 9, characterized in that the inert reinforcing parts have at least one cavity and / or consist of a foam structure.

11. The method according to one or more of claims 1 to 10, characterized in that one tunes the size and number of reinforcing members and the amount of thermally expandable material and the degree of expansion of the thermally expandable material to each other so that after the expansion of the thermally expandable material at least In a cross-sectional area of the hollow component, the cavity is completely filled with the expanded thermally expandable material and the reinforcing part (s).

12. The method according to claim 11, characterized in that one size and number of reinforcing parts and the amount of thermally expandable Material and the degree of expansion of the thermally expandable material coordinated so that the volume of the cavity, which is filled by the expanded thermally expandable material and the reinforcing member or the reinforcing members is filled to at least 50 vol .-% by the reinforcing member or the reinforcing members.

13. The method according to one or more of claims 1 to 12, characterized in that the reinforcing members are round or polyhedral closed or partially open hollow body or pipe sections with round or polygonal cross-section.

14. The method according to one or more of claims 1 to 12, characterized in that the reinforcing members consist of a foam structure and represent round or polyhedral bodies or columns with round or polygonal cross-section.

15. The method according to one or more of claims 1 to 14, characterized in that the thermally expandable material is selected so that it is from 5 to 200% when heated from 20 ⁰ C to a temperature in the range of 130 to 220 ⁰ C. expands.

16. The method according to one or more of claims 1 to 15, characterized in that the thermally expandable material contains at least the following components: a) at least one reactive prepolymer, b) at least one latent blowing agent and, if required for the reaction of component a) , c) at least one latent hardener for the reactive prepolymer.

17. The method according to claim 16, characterized in that the thermally expandable material additionally contains at least one of the following components: d) non-expandable hollow microspheres having an outer diameter in the range of 0.001 to 0.1 mm, e) fibers f) at least one filler which is not hollow microspheres or fibers.

18. The method according to claim 2, characterized in that the thermally expandable material is extruded as a strand and cut into pieces of predetermined length before introduction into the cavity.

19. The method according to one or more of claims 1 to 18, characterized in that one provides in the cavity of the hollow member holding elements, on which soft the reinforcing member or the reinforcing members and the thermally expandable material are applied.

20. The method according to claim 2, characterized in that one arranges parts of thermally expandable material and inert reinforcing parts side by side on a holding device and uses this holding device with the arrangement of the parts of thermally expandable material and the inert reinforcing parts in the hollow component

21. Arrangement of parts of a thermally expandable material and inert reinforcing parts, which are fixed by a holding device relative to each other.

22. An article containing at least one hollow component which has been stiffened, insulated, damped or sealed by a method according to one or more of claims 1 to 20.