DE102009019484A1 - Adhesive composition, useful for bonding components and for detaching bonded components including e.g. metal, plastic, wood and natural or synthetic material, comprises an adhesive matrix with an expansion and a detaching material - Google Patents

Abstract

Adhesive composition (I) comprises an adhesive matrix with at least an expansion material and at least a detaching agent. Independent claims are included for: (1) a method of bonding components comprising applying (I) on at least a surface of at least a component, contacting the adhesive-bearing surface of the component with at least one another component and curing (I) to form an adhesive bond comprising an adhesive layer and at least two components; (2) a method for detaching the bonded components, comprising heating the adhesive layer at an expansion temperature of the expansion material, heating the adhesive layer at a temperature that enables the activation of the detaching agent, and separating the bonded components; and (3) a composite comprising at least two components and the adhesive layer comprising (I).

Description

The The present invention relates to an adhesive composition for releasable adhesive joints based on adhesive matrices with at least one expansion substance and at least one degradation reagent. The invention further relates to their use in releasable Adhesive connections and methods for connecting or disconnecting of adhesive joints in means of transport, in particular in aircraft.

Especially In aircraft are increasingly different metallic and / or non-metallic Components joined together by gluing, on the one hand the Simplify the production process and in proportion to conventional riveting, screwing and / or welding connections Save weight. To repair such connected components, exchange, scrap or recycle However, these bonds are released again. Often designed However, this process is relatively difficult, since the adhesive joints Build up a high bond strength during the application time and thus a release of the adhesive bond only under high force, high temperatures or with the help of chemical agents possible is, with the connected components often damaged or even destroyed. Detachable adhesive compositions are known in different embodiments. In As a rule, these compositions consist of an adhesive matrix (also referred to as a binder matrix) and an expansion substance embedded therein. These expansion substances are said to release the associated Expand components by energy input, so as to the adhesive bond weaken, making the components more easily separated can be. Other compositions contain a degradation reagent, which should chemically attack the adhesive matrix so that the adhesive bond finally can be separated.

The DE 199 61 940 A1 discloses, for example, an adhesive composition whose binder system contains thermally activatable expansion agents that can trigger a detackification process. These thermally activatable substances are solid at room temperature and finely divided homogeneously distributed in the binder matrix. Upon heating, these substances are expected to cause swelling of the binder matrix, undergo phase transformation, decomposition, and / or generate gases or water vapor. Adhesive compositions which, by thermal decomposition of incorporated expansion materials, enable releasable adhesive bonds, are also disclosed in U.S.Pat US 3,615,960 . WO 00/40648 A1 and the DE 10 2004 050 949 A1 described.

The DE 198 32 629 A1 on the other hand relates to an adhesive system for forming reversible adhesive bonds with at least one polymeric adhesive component based on polyurethanes and / or polyureas and / or epoxy resins and at least one degradation reagent in the form of an additional component, wherein the additional component has at least one functional group which can be activated by energy introduction, such that a chemical reaction with the adhesive component takes place with at least partial degradation of the adhesive component.

The Solving such adhesive joints proves, however, often due to the crosslink density of the cured adhesive as difficult as this is a chemical attack by degradation reagents difficult in the adhesive matrix. Furthermore, a high level makes it difficult Crosslinking density of the adhesive also has an expansion of in the Adhesive layer contained expansion materials, so that the adhesive bond here is weakened only slightly and a release the connected components only with an additional to Part considerable mechanical force is possible. To one alternatively, to avoid such mechanical force will become partial very high amounts of expansion substances or degradation reagents, based on the amount of adhesive used. Also for very tough Adhesives like polyurethane adhesives is usually a big one Amount of expansion agents embedded in it needed to ever a sufficient weakening of the adhesive bond and thus to achieve a separation of components. For High performance soluble adhesives is the use of Therefore expansion materials often completely unsuitable. additionally need the surfaces of connected components after a suitable separation usually still chemically or mechanically be cleaned, on remaining adhesive residue completely remove.

Therefore still exists for the production of releasable adhesive bonds a need for adhesive compositions that during the application time in adhesive joints sufficient adhesion develop, but at the same time if necessary without any Residues are easy to solve.

It is therefore an object of the present invention to provide adhesive compositions for releasable adhesive bonds which have sufficient bond strength during the time of use, but which can be readily released as needed, preferably without damaging or destroying the bonded components. A further object is that the adhesive layers, comprising an adhesive composition according to the invention, can be easily removed from the components after dissolution after dissolution without adhesive residues. An additional object is that these adhesive compositions are easy to apply and in the cured form have sufficient chemical and thermal resistance.

The Solving the above and other tasks arises from the subjects of the independent claims. Advantageous embodiments result from their Combination with the features of the dependent claims.

According to one Aspect of the present invention are adhesive compositions provided in an expansion fabric together with a Removal reagent is embedded in an adhesive matrix. Here you can the particles of the degradation reagent are at least partially encapsulated be. These adhesive compositions can be added to any connecting surfaces of components, especially in Applications in the aviation industry, be applied.

in the Difference to the prior art include the inventive Adhesive compositions for releasable adhesive bonds an adhesive matrix and an expansion substance embedded therein and a degradation reagent.

By the joint use of an expansion substance and a degradation reagent have the adhesive compositions according to the invention a number of improved features. First is to note that the release of adhesive joints, comprising the adhesive compositions according to the invention, without damage or destruction of connected Components or their surfaces can be done. Further can solve these adhesive joints without adhesive residue take place on the surfaces of the dissolved components. Furthermore, the amount of energy to be introduced is to release the adhesive bonds compared to conventional adhesive compositions reduced in adhesive bonds. Furthermore, the adhesive compositions excellent adhesive properties. These excellent adhesive properties reflected, among other things in an extended shelf life and application time again, the bond strength with increasing Duration of application remains constant and so early Loosening of correspondingly connected components avoided becomes. Furthermore, the inventive show Adhesive compositions also have less impairment the adhesive characteristics as conventional adhesive compositions.

When Adhesive matrix (also referred to as binder matrix) of the invention Adhesive compositions can use such matrices which are commonly used in industrial applications and in particular of aeronautical engineering. The adhesive matrix can be selected according to their properties, to z. As the bond strength, temperature resistance at high or low Temperatures, deformability, elasticity, resistance against moisture, chemicals and mechanical stress to change.

In Some embodiments are physically setting Adhesives usable. These include hotmelt adhesives, solvent-based wet adhesives, contact and dispersion adhesives, water-based adhesives and plastisols. Preference is given here Adhesive matrices based on ethylene-vinyl acetate copolymers, Polybutenes, styrene-isoprene-styrene or styrene-butadiene-styrene copolymers, thermoplastic elastomers, amorphous polyolefins, linear, thermoplastic polyurethanes, copolyesters, polyamide resins, polyamide / EVA copolymers, Polyaminoamides based on dimer fatty acids, polyester and polyetheramides or mixtures thereof.

In Further preferred embodiments are reaction adhesives such as polymerization adhesives, polyaddition adhesives and polycondensation adhesives usable as adhesive matrix. These include acrylate adhesives, such as As cyanoacrylate adhesives or methyl methacrylate adhesives, anaerobic curing adhesives, unsaturated polyester resins, Radiation-curing adhesives, phenol-formaldehyde adhesives, Silicone adhesives, silane-crosslinking polymer adhesives, polyimide adhesives, Epoxy adhesives and polyurethane adhesives.

Under a one-component adhesive thereby adhesive compositions understood that both corresponding adhesive monomers as well Contain hardener, the glue being changed by a change the ambient conditions hardens. This can be, for example by a temperature increase, access of humidity, exclusion of atmospheric oxygen or contact with the substrate surface happen. In contrast, under two-component adhesives Such adhesive compositions understood in which the corresponding Adhesive monomers and the hardener are stored separately and intensive before the application in the correct ratio be mixed. With the contact of adhesive monomers and hardener starts the chemical reaction to the adhesive polymer.

Especially Preference is given here adhesive matrices on the basis or two-component polyurethanes, one- or two-component polyepoxides, one- or two-component silicone polymers, silane-modified polymers and (meth) acrylate and cyanoacrylate functional reactive adhesives or mixtures thereof.

Especially preferred embodiments of the present invention include one- or two-component polyepoxide adhesives, as well one- or two-component polyurethane adhesives and on or two-component acrylate adhesives, such as. As methyl methacrylate adhesives or cyanoacrylate adhesives as adhesive matrix. Furthermore, can any adhesive matrix that has a sufficient uniform mix forms with the expansion substance and degradation reagent for which present invention can be used.

The Adhesive matrix of the adhesive compositions according to the invention may in an amount of 50 to 99 wt .-%, preferably in one Amount of 65 to 99 wt .-% and most preferably in an amount from 80 to 99 wt .-%, each based on the total weight of Adhesive composition, present.

The for the preparation of the adhesive compositions according to the invention preferred group of expansion materials include those that are included in expand the introduction of a sufficient amount of energy. When Expansionsstoff are referred to in particular such substances, in the introduction of heat energy in the adhesive matrix expand sufficiently to weaken corresponding ones To lead adhesive bonds. These include such expansion substances understood that decompose in the introduction of energy and while gases such as nitrogen or carbon dioxide form and thus lead to an expansion of the expansion substance. But this also means such expansion substances that include additional substances that are introduced by the introduction of energy undecomposed evaporate and thus also to an expansion of the expansion substance. These released vapors in turn can chemically attack the expansion substance and with the release of gases to a further expansion of the Lead expansion substance.

The The introduction of energy can in principle be effected by any form of energy, for example by means of elevated temperature or inductive through the use of an electric field, magnetic field, electromagnetic Field, alternating electric field, alternating magnetic field or alternating electromagnetic field, as well as by means of IR, UV or microwave energy respectively. Furthermore, such expansion substances are preferred which only at temperatures above the service temperature of the adhesive expand. Furthermore, the expansion materials should preferably not be toxic and / or be poor in solubility Have adhesive matrix.

Of the Inventive expansion material is so in the Adhesive matrix distributed, that this preferably in the places where its action is needed. In a preferred Embodiment, the expansion substance is possible homogeneously distributed in the adhesive matrix in order to introduce a sufficient amount of energy to release the adhesive bond a uniform as possible weakening to achieve the adhesive bond. In a further embodiment However, it may be advantageous that the expansion substance in nonuniform the adhesive layer is distributed so as to introduce sufficient Amount of energy to release the adhesive bond a partial and / or localized weakening of this adhesive bond to achieve.

Especially suitable as the expansion substance of the present invention are all natural, semi-synthetic and synthetic materials, in particular inorganic and / or organic expansion substances, which under the conditions used sufficient expansion show to solve an adhesive bond.

The for the preparation of the expansion materials according to the invention usable inorganic and / or organic materials In certain embodiments, foamable materials, blowing agents and intumescent substances. Intumescent substances are materials that under the influence of heat of an increase in volume and / or a decrease in density subject.

In One embodiment is the organic expansion substance for example, selected from the group consisting of Azoisobutyronitrile (AIBN), azodicarbonamide (ADC), dinitrosopentamethylenetramine (DPT), benzenesulfonylhydrazide, N, N'-dinitroso-N, N'-dimethylterephthalamide, p, p-oxy-bis-benzenesulfonylhydrazide (OBSH), p-toluenesulfonyl hydrazide (TSH), 5-phenyltetrazole (5-PT), sulfonyl semicarbazides such. B. p-toluenesulfonyl semicarbazide (PTSS) or mixtures thereof. These Group of organic expansion substances decomposes if sufficient Energy input preferably to form nitrogen and / or volatile hydrocarbons or carbon dioxide, which leads to an expansion of the expansion substance and thus to a weakening of the Adhesive connection leads.

In a further embodiment, the substances which can be used for the production of the expansion materials according to the invention comprise inorganic expansion substances selected from the group consisting of expandable graphites (EG), mica, vermiculite, hydrotalcite or mixtures thereof. This group of inorganic expansion materials preferably includes additional reagents, such as. As acids, which evaporate by the introduction of energy undecomposed, and thus lead to an expansion of the expansion substance. Furthermore, the liberated acid vapors, but also the liquid acid, especially at elevated temperature, chemically attack the enclosed expansion substance and lead to the release of gases to a further expansion of the expansion substance.

A preferred embodiment of the present invention Azodicarbonamide (ADC) as organic according to the invention Expansion fabric. Another preferred embodiment The present invention includes expandable graphites (EG) as Inventive inorganic expansion substance. Other embodiments include mixtures of the above said inorganic and organic expansion materials.

Especially preferred embodiments of the present invention include one- or two-component polyurethane adhesives as adhesive matrix and azodicarbonamide (ADC) as organic expansion agent. A another particularly preferred embodiment of the present invention Invention includes one or two component polyepoxide adhesives as an adhesive matrix and azodicarbonamide (ADC) as an organic expansion substance. Another particularly preferred embodiment of the present invention Invention includes one- or two-component acrylate adhesives as an adhesive matrix and azodicarbonamide (ADC) as an organic expansion substance. Further includes a particularly preferred embodiment of the present invention Invention one- or two-component polyurethane adhesives as Adhesive matrix and expandable graphites (EG) as inorganic Expansion fabric. Another particularly preferred embodiment of the present invention comprises one or two component polyepoxide adhesives as an adhesive matrix and expandable graphites (EG) as inorganic Expansion fabric. Another particularly preferred embodiment The present invention encompasses one- or two-component acrylate adhesives as an adhesive matrix and expandable graphites (EG) as inorganic Expansion fabric.

Of the Content of the invention used at least An expansion substance may vary within a wide range but lie in an area in which there is still sufficient adhesive power achieved in an adhesive bond. In some embodiments Therefore, the amount of the expansion substance should be at most 45% by weight, more preferably at most 30% by weight and most preferably at most 15% by weight, each based on the total weight of the adhesive composition.

Of the Expansion material should also be added in quantity be that sufficient expansion after energy injection guaranteed to release the adhesive bond. preferably, Therefore, the proportion of the expansion substance in a tonnage range of at least 1% by weight, preferably in a range of at least 5% by weight and most preferably in a tonnage range of at least 10 wt .-%, each based on the total weight of the adhesive composition.

Certain Embodiments therefore preferably include 1 to 45 Wt .-%, more preferably 5 to 30 wt .-% and most preferably 10 to 15 wt .-% of the expansion substance, each based on the Total weight of the adhesive composition.

Preferably is the expansion substance used in the invention Resistant to temperatures that commonly occur during curing of adhesive compositions in adhesive bonds. Furthermore, the expansion substance should be chosen so that the bonded components under application conditions commonly used in of aeronautical engineering, a sufficient resistance exhibit.

In certain embodiments, the expansion substance a thermal resistance at a temperature of about 180 ° C for about 2 hours, more preferably at a temperature of about 190 ° C for about 2 Hours and most preferably at a temperature of about 200 ° C for about 2 hours. In particular, the expansion substance a thermal resistance up to a temperature of about 180 ° C for a period of 2 hours.

In Another preferred embodiment of the present invention Invention, the expansion substance has a lasting thermal stability in a field of application that is commonly used in aeronautical engineering occurs. In a particularly preferred embodiment indicates the expansion substance according to the invention therefore a lasting thermal stability up to a temperature from 100 ° C, more preferably to a temperature from 120 ° C, and most preferably up to a temperature of 140 ° C. The expansion substance of the present invention has In addition, sufficient stability at low Temperatures, preferably up to a temperature of -50 ° C, more preferably up to a temperature of -75 ° C and most preferably up to a temperature of -100 ° C.

Certain Embodiments of the present invention therefore have a lasting stability in a temperature range of -50 ° C to 100 ° C, more preferably within a range of -75 ° C to 120 ° C and most preferably in a range of -100 ° C up to 140 ° C.

The expansion substances can be in particulate In general, they have a mean particle size of <1 mm, preferably an average particle size of <500 μm, more preferably a particle size of <250 μm and most preferably an average particle size of <100 μm. However, the average particle size should be less than the layer thickness of the adhesive layer of the cured adhesive composition. Preferably, the expansion agents have an average particle size of 1 to 100 microns and more preferably between 2 and 50 microns.

When further constituent comprises the inventive Adhesive composition at least one degradation reagent. Be under degradation reagents In this case understood such substances that can be activated by energy input are so that as a result of a chemical reaction with the adhesive matrix a strong change in molecular weight and / or crosslink density the adhesive matrix occurs and leads to a loss of mechanical Strength of the adhesive leads. The main task of the Degradation reagent in the adhesive compositions is the targeted at least partial degradation of the cured adhesive matrix upon introduction a sufficient amount of energy in the adhesive layer of the adhesive bonds, so that the adhesive joints can be solved more easily. The degradation reagents are in one embodiment distributed as homogeneously as possible in the adhesive matrix in order to Introducing a sufficient amount of energy to release the Adhesive connection as even as possible To achieve degradation of the adhesive matrix. In a further embodiment however, it may be advantageous for the degradation reagent to be uneven is distributed in the adhesive layer to when introducing a sufficient Amount of energy to release the adhesive bonds only a partial and / or localized weakening of the adhesive bonds to achieve.

When In principle, degradation reagents are all organic or inorganic compounds, salts, metals, metal compounds or Materials considered to be a degradation of the respective cured Adhesive matrix are capable and in the adhesive composition show sufficient stability. Here are in particular such substances suitable as degradation reagents, which is a chemical cleavage a bond in the polymer backbone of the corresponding adhesive matrix cause and thus to a weakening of the adhesive bond to lead.

Under these are organic in certain embodiments Hydrazides, amines, especially primary and secondary Amines, amides and polyfunctional compounds are preferred, if appropriate also triazines. Examples of degradation reagents on the base hydrazides include, in particular, carbohydrazide, isophthalic dihydrazide, Adipic dihydrazide, oxalic dihydrazide, malonic dihydrazide, Succinic dihydrazide, glutaric dihydrazide, Sebazine dihydrazide, maleic dihydrazide, Fumaric dihydrazide, glutamic acid dihydrazide, Itaconic dihydrazide, butadienedihydrazide, Aspartic dihydrazide, maleic dihydrazide, Tartaric dihydrazide, terephthalic acid bis-hydrazide, Isophthalic bishydrazide, phthalic acid bis-hydrazide, Cyclohexanedicarboxylic acid dihydrazide and cyclohexylmethylmalonic acid dihydrazide, p-toluenesulfonylhydrazide, 1,3,5-triisopropylbenzenesulfonyl hydrazide or mixtures thereof.

Examples for degradation reagents from the group of amines include in particular Diaminobenzidine, benzidine, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,3-diaminobenzene, 1,5-diaminonaphthalene, 3,4-diaminotoluene, o-ethylenedianiline, p-ethylenedianiline, 2,3,5,6-tetramethyl-1,4-phenylenediamine, triaminoethylamine, 4,4'-diaminodiphenylmethane, diethanolamine, diisopropanolamine, bisethylenetriamine, bishexamethylenetriamine, bisethylenetriamine, aromatic polyamines and mixtures thereof.

Examples for degradation reagents based on triazines in particular tris (4-aminophenoxy) -1,3,5-triazine, 2,4,6-tris (ω-hydroxypolyalkoxy) -1,3,5-triazine, 1,3,5-triazine-2,4-diamine, 1,3,5-triazine-2,4,6-triamine, 1,3,5-triazine, 2,4-diamino-6- [2- (2-methyl-1 H -imidazol-1-yl) ethyl] triazine, tris (2-methylimidazol-1-yl) triazine, Tris (2-ethyl-4-methylimidazol-1-yl) triazine, tris (2-phenylimidazol-1-yl) triazine and mixtures thereof.

A Particularly preferred embodiment includes carbohydrazide as degradation reagent of the adhesive composition according to the invention.

Especially preferred embodiments of the present invention include one- or two-component polyurethane adhesives as adhesive matrix, Azodicarbonamide (ADC) as organic expansion agent and carbohydrazide as a degradation reagent. Another particularly preferred embodiment of the present invention comprises one or two component polyepoxide adhesives as adhesive matrix, azodicarbonamide (ADC) as organic expansion substance and carbohydrazide as a degradation reagent. Another particularly preferred Embodiment of the present invention comprises on or two-component polyepoxide adhesives as adhesive matrix, expandable Graphite (EG) as an inorganic expansion substance and carbohydrazide as a degradation reagent.

The degradation reagents are preferably present in particulate form, wherein the particles of the degradation reagent are protected by attachment of protective groups or complexation with a complexing agent, so that the reactivity of functional Groups of the degradation reagent is reduced.

Preferably The degradation reagents are thereby in a metal halide complex Complexed and so on a premature or unwanted degradation of Adhesive matrix prevented. As complexing agent of the degradation reagent Therefore, in particular, such materials can be used which, together with the degradation reagent, are essentially stable complexes form, and essentially at a pressure load, or high or low temperatures, as commonly used in the aircraft industry occur, do not dissolve or decompose.

In certain embodiments are therefore inorganic salts as a complexing agent for degradation reagents based on Amines are preferred, especially those which are selected from the group consisting of lithium bromide and sodium chloride.

Especially preferred embodiments of the present invention include triaminoethylamine as degradation reagent and lithium bromide as Complexing agent. Another particularly preferred embodiment The present invention includes 4,4'-diaminodiphenylmethane as Degradation reagent and sodium chloride as complexing agent.

The Particles of the degradation reagent can also be at least partially, preferably completely, encapsulated. Under an encapsulated degradation reagent are within the meaning of the present Invention such degradation reagents understood by a shell material or a coating on premature or unwanted degradation the adhesive matrix are prevented. As wrapping material or coating material of the encapsulation can therefore such materials are used, which are a shell or Form the layer around the degradation reagent so that the adhesive matrix Protected before and after curing before enclosed in the degradation reagents becomes. In addition, the wrapping material or Coating material of the degradation reagent of the invention in an area that commonly occurs in aviation, be thermally stable to the protection of the trapped therein Assay degradation and premature degradation to avoid the adhesive matrix. Furthermore, the wrapping material should or coating material of the degradation reagent in a targeted Energy input removable, for example, breakable or meltable so that the degradation reagent to release the adhesive bond can be released.

When Covering material or coating material of the degradation reagent Therefore, in particular, such materials can be used which are essentially at a pressure load, or high or low temperatures, as is common in the aircraft industry occur, do not melt, deform, dissolve or break / tear.

In In certain embodiments, polymers are based on of thermoplastic polymers, especially those selected are from the group consisting of low density polyethylene (LDPE), High density polyethylene (HDPE), polyethylene terephthalate (PET), Polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyester (PE), polyamide (PA), polylactate (PL), polymethyl methacrylate (PMMA), Nylon and acrylonitrile butadiene styrene (ABS), acetal, acrylic acid, Cellulose acetate (CA), cellulose acetate butyrate (CAB), ethylene vinyl acetate (EVA), Phenylene oxide based, polyurea and polysulfone polymers and Ethylene-acrylic acid copolymer (EAA), phenol-formaldehyde resin, Urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin, Vinyl chloride / acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, Polyacrylonitrile and glass ethylene-methacrylic acid copolymer (EMA), polyvinyl chloride (PVC) and ethylene-based copolymers, the neutralized with metal salts (ionomers) or mixtures thereof, as shell material or coating material of the encapsulated Removal reagent usable.

In a particularly preferred embodiment is the shell material or coating material of the encapsulated degradation reagent made of polyureas. Furthermore, any shell material or coating material can be used which has a sufficient Guaranteed protection of the adhesive matrix against the degradation reagent.

Especially preferred embodiments of the present invention include one- or two-component polyurethane adhesives as adhesive matrix, Azodicarbonamide (ADC) as organic expansion agent and carbohydrazide as degradation reagent, wherein the shell material of the degradation reagent Polyureas comprises. Another particularly preferred embodiment of the present invention comprises one or two component polyepoxide adhesives as adhesive matrix, azodicarbonamide (ADC) as organic expansion substance and carbohydrazide as a degradation reagent, wherein the shell material of the Degradation reagent comprises polyureas. Another particularly preferred Embodiment of the present invention comprises a or two-component polyepoxide adhesives as adhesive matrix, expandable Graphite (EG) as an inorganic expansion substance and carbohydrazide as degradation reagent, wherein the shell material of the degradation reagent Polyureas comprises.

The wrapping material or coating material al of the degradation reagent according to the invention is adjusted so that it is thermally stable. Preferably, the shell material or coating material of the encapsulated degradation reagent ensures that it is stable at temperatures commonly encountered in curing adhesive compositions in adhesive bonds.

In certain embodiments ensures that Covering material or coating material of the degradation reagent a thermal resistance at a temperature of about 160 ° C for about 2 hours, more preferably at a temperature of about 170 ° C for about 2 Hours and most preferably at a temperature of about 180 ° C for about 2 hours. In particular, guaranteed the shell material of the encapsulated degradation reagent has a thermal stability up to a temperature of about 200 ° C for a Duration of 2 hours.

In Another preferred embodiment of the present invention Invention ensures the shell material or Coating material of the degradation reagent a lasting thermal Stability in a range of application, usually occurs in aviation technology. In a particularly preferred Embodiment ensures the inventive Degradation reagent therefore a lasting thermal stability up to a temperature of 100 ° C, more preferably to to a temperature of 120 ° C and most preferred up to a temperature of 140 ° C. The degradation reagent of The present invention also provides sufficient Stability at low temperatures, preferably until to a temperature of -50 ° C, more preferably up to a temperature of -75 ° C and most preferably up to a temperature of -100 ° C.

Certain Embodiments of the present invention show in particular a lasting stability in a temperature range from -50 ° C to 100 ° C, more preferably in the range of -75 ° C to 120 ° C and most preferably in a range of -100 ° C up to 140 ° C.

Preferably The particles of the degradation reagent are at least partially encapsulated before, that means that the degradation reagent is at least partially enclosed by the wrapping material or coating material is. In a preferred embodiment, 70 to 100% the surface of the degradation reagent with the shell material or coating material, preferably 80 to 100%, still more preferably 90 to 100%, and most preferably 95 to 100%. In a particularly preferred embodiment is the degradation reagent completely in the shell material or coating material locked in. In a further particularly preferred embodiment the degradation reagent is complexed in a metal halide complex, allowing the reactivity of functional groups of the degradation reagent is lowered.

in the Generally, the degradation reagents have an average particle size of <1 mm, a particle size of <500 μm is preferred, even more preferred is a particle size of <250 microns and most preferred is a particle size of <100 μm. However, the average particle size should be lower be as the layer thickness of the adhesive layer of the cured Adhesive compositions. Preferably, the degradation reagents have a average particle size of 1 to 150 microns and more preferably between 5 and 75 microns.

The Expression of the weakening of the adhesive matrix when releasing an adhesive bond can by the proportion the degradation reagent can be influenced and varied, since the achievable Weakening the adhesive bond from the concentration and depends on the type of degradation reagent. By an increase the amount of degradation reagent in the invention Adhesive compositions can be correspondingly greater weakenings achieve the adhesive joints, so that they separate easily to let.

Of the Content of used degradation reagent in the inventive Adhesive compositions can therefore vary within a wide range, but should in some embodiments at most 30% by weight, more preferably at most 20% by weight and most preferably at most 10% by weight, each based on the total weight of the adhesive composition.

The Degradation reagent should also be added in quantities allowing a sufficient weakening of the adhesive bonds or a slight removal of adhesive residues can be achieved. Preferably, therefore, the proportion of the Degradation reagent at least 0.5% by weight, more preferably at least 1% by weight, and most preferably at least 2% by weight, respectively based on the total weight of the adhesive composition.

Certain embodiments therefore preferably comprise 0.5 to 30 wt%, more preferably 0.5 to 20 wt%, and most preferably 0.5 to 10 wt% of the degradation reagent, based in each case on the total weight of the adhesive. Composition. By contrast, further embodiments preferably comprise from 1 to 30% by weight, more preferably from 1 to 20% by weight and most preferably from 1 to 10% by weight of the degradation reagent, based in each case on the total weight of the adhesive composition. By contrast, further embodiments preferably comprise from 2 to 30% by weight, more preferably from 2 to 20% by weight and most preferably 2 to 10 wt .-% of the degradation reagent, each based on the total weight of the adhesive composition.

In certain embodiments include the adhesive compositions preferably at most 60% by weight, more preferably at most 40% by weight and most preferably at most 20% by weight on expansion substance and degradation reagent, in each case based on the total weight the adhesive composition. In order to ensure sufficient degradation or Weakening of the adhesive matrix to release the adhesive bonds to ensure, however, the compositions should at least 1 wt%, more preferably 5 wt%, and most preferably at least 7.5% by weight of the expansion agent and degradation reagent.

The According to the invention encapsulated degradation reagents can be prepared by all common methods, by the degradation reagent can be encapsulated or coated. In particular, can such encapsulation or coating of the degradation reagent all common microencapsulation processes are achieved, in particular by interfacial polymerization, in situ polymerization or matrix polymerization. However, other methods are also suitable for the encapsulation or coating of substances, such as fluidized bed technology, coacervation, spray-drying or sol-gel methods.

Farther can mixable additives to the adhesive compositions added to the present invention as desired be such. As hardeners, accelerators, catalysts, additional resins for improving the adhesive properties, Thixotropic agents, plasticizers, tougheners, adhesive adjuvants, stabilizers, Dyes, surfactants, modifiers, fillers, solvents and the like, commonly used in adhesive compositions used, but the essential characteristics of the composition do not worsen.

The adhesive compositions according to the invention can be used to connect or disconnect components made of metal, plastic, in particular heat-resistant Plastic, wood, glass, natural or synthetic materials or composite materials used therefrom. They come therefore for gluing or joining components in the interior and outdoor, of furniture, doors, window frames, industrial components for the private and industrial Use and for components in transport devices of any kind Art, including aircraft, motor vehicles and ships into consideration. Especially preferred are applications in the field of aviation technology.

The Adhesive compositions of the present invention may doing so directly in the form of a liquid to be connected Components are applied, with an adhesive layer of the respective Adhesive composition is formed. In one embodiment For example, the adhesive compositions may preferably only on the surface of a component that matches the surface another component is to be connected, applied and then be contacted with this. In a further embodiment can the adhesive compositions on the surface of two or several components to be joined, which are subsequently applied be brought into contact with each other. In a further embodiment First, a layer of the respective adhesive composition be formed and dried on a flexible film. Subsequently This dry film can be used to join the To fasten / glue components.

The Application of the adhesive compositions can be in any form which ensures that the adhesives are the surfaces coat the components in the desired manner. To the For example, the adhesive compositions can be sprayed or through a brush or roller or pouring be applied to the surfaces. Another possibility is that the components to be joined in the adhesive compositions be immersed.

One A method of joining components may be that an adhesive composition according to the invention on the surface of at least one component by conventional Method is applied and the components to be joined together be brought into contact. The corresponding adhesive bond comprising an adhesive layer and at least two components, can then by means of elevated temperature or inductively through the use of a electric field, magnetic field, electromagnetic field, alternating electric field, alternating magnetic field or electromagnetic Alternating field to a temperature at which the crosslinking of the adhesive matrix used, heated and cured the adhesive composition become.

The time interval for curing the adhesive compositions in the respective adhesive compositions may vary depending on the composition and optionally used additives. The duration of curing is in the inductive method in the second to minute range, while in the thermal curing process complete curing usually within a few hours, preferably within 2 hours, can be achieved. Thus, the invention Adhesive compositions are particularly suitable for joining sensitive components.

Of the by curing the invention Adhesive compositions obtained composite of components thus at least two components and an adhesive layer in the form an adhesive bond, wherein the adhesive layer is an inventive Adhesive composition comprises.

The inventive method for solving the adhesive bond by curing the inventive Adhesive compositions can be obtained in such a way be carried out that the cured adhesive layer the adhesive bond by means of elevated temperature, for. B. in an air oven or inductively by the use of an electric Field, magnetic field, electromagnetic field, electric Alternating field, alternating magnetic field or electromagnetic alternating field is heated. In a further embodiment The required energy can also be obtained by means of IR, UV or microwave energy be introduced. In the case of energy input by means of microwave energy can solve the adhesive bond already within less Minutes (eg up to 10 minutes).

at This procedure should use the temperature to activate the degradation reagent and the expansion temperature of the expansion substance in temperature ranges lie about the usually in the aviation technology occurring temperatures. In a particularly preferred Embodiment, the components finally be separated by hand. In another particular preferred embodiment, the adhesive layer may finally without residue from the connected components be removed.

In a preferred method for releasing the adhesive bond the adhesive layer in the adhesive bond is at a temperature heated enough to activate the degradation reagent, d. H. that the shell material or coating material of the Degradation reagent melts, breaks up / breaks up or dissolves, so that the degradation reagent is released. This can cause a release the adhesive bond in the form that the molecular weight of the adhesive matrix lowered due to a chemical degradation by the degradation reagent and so on with a further increase in temperature a largely unhindered expansion of the expansion substance can be done in this weakened adhesive matrix. In this embodiment is thus the temperature, the is required to activate the degradation reagent, lower than the expansion temperature of the expansion substance. The required temperature to activate the degradation reagent as well as the expansion temperature of the expansion substance are dependent on the used Adhesive matrix or the degradation reagents and expansion agents used.

Preferably the temperature for activating the degradation reagent is in a range between 120 and 280 ° C, more preferably in a range between 150 and 250 ° C and most preferred in a range between 180 and 210 ° C. The expansion temperature of the expansion substance is preferably in this embodiment in a range between 140 and 300 ° C, more preferably in a range between 170 and 270 ° C and most preferably in a range between 120 and 230 ° C. The Expansion temperature is about particularly preferred method 40 ° C higher, more preferably about 30 ° C higher and most preferably about 20 ° C higher as the temperature used to activate the degradation reagent becomes.

In a particularly preferred embodiment is this Process for very tough adhesive compositions suitable, since by the degradation of the adhesive matrix already a weakening of the Adhesive connection occurs, whereby an improved expansion of the Expansion substance for releasing the adhesive connection possible is. This method is therefore especially for adhesive composition based on polyepoxide, polyurethane and acrylate adhesives suitable.

In In another embodiment, on the other hand, the adhesive layer becomes the adhesive joint is heated to a temperature that is initially only leads to an expansion of the expansion substance. This can a release of the adhesive bond in the form take place that first the adhesive matrix through the expanding expansion substance is weakened and after another increase the temperature is an activation of the degradation reagent, the allows degradation of the adhesive matrix. In this embodiment thus lies the temperature necessary for an expansion of the Expansion substance is required, lower than the temperature, which is needed to activate the degradation reagent.

In a particular embodiment, this method can be used to first solve the adhesive bond between connected components and then, after a renewed increase in temperature, to allow the removal of adhesive residues on these components by activating the degradation reagent. The required expansion temperature of the expansion substance, as well as the temperature for activating the degradation reagent, are dependent on the adhesive matrix used or the Ab used construction reagents and expansion substances.

Preferably the expansion temperature of the expansion substance is in one Range between 120 and 280 ° C, more preferably in one range between 150 and 250 ° C, and most preferably in one Range between 180 and 210 ° C. The temperature to activate the degradation reagent is preferably in this embodiment in a range between 140 and 300 ° C, more preferably in a range between 170 and 270 ° C and most preferably in a range between 120 and 230 ° C. The Temperature for activating the degradation reagent is in a particularly preferred Process about 40 ° C higher, more preferably about 30 ° C higher, and most preferably about 20 ° C higher than the expansion temperature of the expansion substance. In a particular embodiment, this method becomes especially for less tough adhesive compositions used, since here an expansion of the expansion materials in the adhesive matrix is possible, so that already a weakening of the Matrix occurs, causing a lighter degradation of the adhesive matrix by the degradation reagent for releasing the adhesive bond possible is.

In According to another embodiment, the adhesive layer is the Adhesive bond heated to a temperature that both to an expansion of the expansion substance as well as to activate the degradation reagent leads. This can be simultaneously Degradation of the adhesive matrix by the degradation reagent and an expansion of the expansion substance in the matrix for releasing the adhesive bond respectively. In this embodiment, therefore, the expansion temperature of the expansion substance as well as the temperature for activating the Degradation reagent in a similar area, with the required Expansion temperature of the expansion substance and the temperature To activate the degradation reagent thereby depend on the adhesive matrix used or the degradation reagents used and expansion materials.

Preferably are the expansion temperature of the expansion substance and the temperature for activating the degradation reagent in a range between 120 and 280 ° C, more preferably in a range between 150 and 250 ° C, and most preferably in a range between 180 and 210 ° C. The expansion temperature of the expansion substance and the temperature for activating the degradation reagent are thereby in particular by at most about 15 ° C, more preferably at most about 10 ° C and most preferred at most about 5 ° C apart.

The Loosening the adhesive joints can usually with used for these purposes. The required devices, parameters and device settings depend on the adhesive composition used from. Furthermore, the temperature required for releasing depends from the thermal stability of each microencapsulated Expansion substance and optional active fillers and their content in the adhesive matrix from. Due to the local proximity the shell material and the optional active fillers to the expansion material enclosed in the shell material the introduction of energy and thus the release of the Adhesive bond particularly effective.

preferred Embodiments of the present invention include or two-component polyurethane adhesives as adhesive matrix, azodicarbonamide (ADC) as organic expansion substance and carbohydrazide as degradation reagent, wherein the shell material of the degradation reagent polyureas includes. Another preferred embodiment of the present invention Invention includes one or two component polyepoxide adhesives as adhesive matrix, expandable graphites (EG) as inorganic Expansion substance and carbohydrazide as degradation reagent, wherein the shell material the degradation reagent comprises polyureas.

in the The following are examples of advantageous embodiments the adhesive compositions of the invention listed,% are given as wt .-%, based on the total weight of the adhesive composition indicated:

example 1

A polyurethane adhesive (Pliogrip 9400/9405) was mixed with 12 wt .-% azodicarbonamide (ADC; Porofor ADC ^® M / C1, manufactured by Lanxess AG, Leverkusen, Germany) as an expansion agent and 5 wt .-% carbohydrazide (CHz; Sigma -Aldrich, Germany) mixed homogeneously with a polyurea wrapping material as a degradation reagent using a SpeedMixer. Subsequently, 2 components made of a fiber-plastic composite material (CFRP) were brought into contact with this adhesive composition and the adhesive bond was cured.

Example 2

The adhesive compound of Example 1 was placed in an air oven at 200 ° C for releasing the adhesive bond. Within 5 minutes, the components could be easily separated. The components were then heated with the surface adhesive residues at 220 ° C for 30 minutes, whereby the adhesive residues became viscous and from the surfaces of the components without additional chemical or mechanical Treatment could be removed.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19961940 A1 [0003]
• - US 3615960 [0003]
• WO 00/40648 A1 [0003]
• DE 102004050949 A1 [0003]
• - DE 19832629 A1 [0004]

Claims (15)

Adhesive compositions for releasable adhesive bonds, wherein the adhesive compositions comprise an adhesive matrix having at least an expansion substance and at least one degradation reagent. Adhesive compositions according to claim 1, wherein the expansion substance is selected from at least one substance the group consisting of an inorganic expansion substance or an organic expansion substance. Adhesive compositions according to claim 2, wherein the organic expansion substance azodicarbonamide (ADC), or the inorganic Expansion Material Expandable Graphite (EG) comprises. Adhesive compositions according to any one of the claims 1 to 3, wherein the degradation reagent selected at least one substance from the group consisting of hydrazides, amines, polyfunctional Compounds or mixtures thereof, more preferably Carbohydrazides. An adhesive composition according to any one of the claims 1 to 4, wherein the amount of the expansion substance 1 to 45 wt .-% is more preferably 5 to 30% by weight and most preferably 10 to 15 wt .-%, each based on the total weight the adhesive composition and / or the amount of the degradation reagent 0.5 to 30% by weight, more preferably 0.5 to 20 Wt .-% and most preferably 0.5 to 10 wt .-%, each based on the total weight of the adhesive composition. Adhesive compositions according to any one of the claims 1 to 5, wherein the particles of the degradation reagent by complexing agents protected, at least partially encapsulated and / or coated are particularly preferred, the particles of the degradation reagent in Essentially completely encapsulated and / or coated. Adhesive compositions according to any one of the claims 1 to 6, wherein the adhesive matrix is selected from the Group consisting of hotmelt adhesives, solvent-based Wet adhesives, contact and dispersion adhesives, water-based adhesives, Plastisols, polymerization adhesives, polyaddition adhesives, Polycondensation adhesives or mixtures thereof. A method of joining components comprising the following steps: a) Applying an adhesive composition according to one of claims 1 to 7 on at least one surface of at least one component, b) contacting the adhesive-carrying Surface of the component from step a) with at least one another component and c) curing the adhesive composition for producing an adhesive bond comprising an adhesive layer and at least two components. A method of releasing according to claim 8 connected components, comprising the following steps: a) Heating the adhesive layer to at least the expansion temperature of the expansion substance, b) heating the adhesive layer to a minimum temperature required to activate the degradation reagent is and c) separating the connected components. The method of claim 9, wherein the adhesive bond first heated to the expansion temperature of the expansion substance and then to the temperature required to activate the degradation reagent is required. The method of claim 9, wherein the adhesive bond only to the temperature required to activate the degradation reagent is heated, and then to the expansion temperature of Expansion substance. Composite of at least two components and one Adhesive layer, wherein the adhesive layer is an adhesive composition according to any one of claims 1 to 7. The composite of claim 12, wherein the component is made of Metal, plastic, wood, glass, natural or synthetic Material or a composite material thereof. Use of an adhesive composition according to one of claims 1 to 7 or a composite according to one of claims 12 or 13 in aircraft, vehicle or shipbuilding. Aircraft, vehicle or ship construction, comprising an adhesive composition according to any one of the claims 1 to 7 or a composite according to one of claims 12 or 13.