Use of a curable and re-dissolvable compound for producing a part, and compound for same

Abstract

The invention relates to a curable compound which is used to produce a part with a thermomechanically releasable joint connection, a coating, or a potting material. The compound has the following components: (a) at least one epoxy compound which comprises at least one di-functional or higher functional aromatic epoxy; (b) at least one curing agent which is suitable for the epoxy curing process; (c) optionally an accelerator for the epoxy curing process; (d) at least one polymer filler in a proportion of 15 wt.% or more, based on the total weight of the compound, said polymer filler being selected from the group of polyamides; (e) optionally one or more compounds which can be cured by means of radical polymerization; (f) optionally at least one initiator for the radical polymerization; and (g) optionally additional additives, wherein the polymer filler is present in the compound as an at least partially crystalline solid, and the melting point of the polymer filler equals at least 120 °C. The invention additionally relates to a method for producing components using the compound and to components produced using said method.

Description

[0001] Use of a hardenable and re-soluble mass for the production of a component, and mass therefor

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the use of a curable composition for producing a component with a thermomechanically removable joint, a coating, or a potting compound, and to a curable composition for producing the component. The curable composition comprises at least one epoxy compound, a curing agent for the epoxy compound, and a polymeric filler.

[0004] Furthermore, the invention relates to a method for producing a component with a thermomechanically removable joint, a coating or a casting using the curable mass, and to a component obtainable by the method.

[0005] TECHNICAL BACKGROUND

[0006] The circular economy strives for a system in which the use of resources and the production of waste are minimized, for example by closing energy and material cycles. From this perspective, the recycling of components or parts in industry represents a major challenge. Particularly in the case of high-priced parts or parts with a limited global availability that experience relatively little aging over a long service life, there is a strong desire to reuse these parts directly or in recycled form in new product generations. However, the components are often located in complex devices that first have to be dismantled in order to separate the parts from other components. In the spirit of the circular economy, it is desirable to use as little energy as possible during dismantling and to avoid harsh processes such as pyrolysis.In addition, for ecological reasons, the use of solvents during disassembly is essential. Accordingly, the state of the art requires materials that enable the removal of joints with a reasonable amount of energy and under the mildest possible conditions. At the same time, these materials must not shorten the service life of the machine or impair its performance during operation.

[0007] There are various approaches to making joints removable in the current state of the art. Often, the joining partners are separated thermomechanically, applying heat through mechanical force. Other options include the use of solvents, pyrolysis, exposure to light, or energization of the joint.

[0008] EP 1 096 517 A2 discloses a recycling process for producing magnetic powder from bonded magnets. The bond comprises thermoplastic materials and is dissolved by solvents under harsh conditions.

[0009] WO 1998 031 738 A1 describes epoxy-amine compositions with a modified amine hardener, which also contain a plasticizer. The compositions are intended for use in bonding semiconductor elements in conjunction with repairs. The repair process involves softening the cured composition by exposure to 250 °C hot air for one minute.

[0010] JP 3 808 819 B2 describes a process for recycling bonded magnets by treating them with hot water and subsequently peeling them off. The adhesive used to hold the magnets in position also contains organic, thermally expandable particles that expand when exposed to hot water at temperatures between 70 and 120 °C. Such materials are unsuitable for magnets such as those used in high-performance electric motors, since the specified peeling temperature is regularly reached or exceeded even during normal operation. US Pat. No. 5,872,158 A describes removable materials based on (meth)acrylates containing acetal-functionalized diacrylates. The disclosure provides for the dissolution of the cured material by treatment with dilute acid, thereby cleaving the acetal groups.

[0011] US 2007 0 196 612 A1 describes die attach compounds based on epoxides, (partially) fluorinated aromatic amine hardeners, inorganic fillers, and organic additives. The organic additives include, among others, polyacrylates, butadiene-styrene copolymers, polyamides, and EVA copolymers. A proportion of more than 20 wt.% organic additives is excluded, as this would adversely increase the viscosity of the compounds. To detach a silicon chip from the cured compound, it is treated with a mixture of solvents such as N,N-dimethylformamide or bis(2-methoxyethyl) ether. This approach is ecotoxicologically questionable and can also cause undesirable damage to surrounding components.

[0012] WO 2021 033 368 A1 discloses epoxy-amine compositions that additionally contain a polymeric component and at least one inorganic filler. The polymeric component comprises at least one phenoxy resin dissolved in the compositions. The re-detachment of joints is not intended.

[0013] EP 2 084205 B1 describes fiber-reinforced composites containing at least one difunctional and additionally one trifunctional epoxy resin. Nitrogen-based compounds are proposed as hardeners. In addition, insoluble particles from the polyamide group are added to the compounds. These improve the so-called CAI (compression after impact) value and thus the mechanical recovery behavior of the cured compounds. The re-removability of the compounds is not described. Instead, the use of the compounds in the aerospace industry as a matrix for the production of prepregs is described.

[0014] The materials described in the prior art either require very harsh conditions for redetachment or are not suitable for long-term use as joining materials in machines that are already subject to high thermal stress during normal operation. SUMMARY OF THE INVENTION

[0015] The invention is based on the object of avoiding the disadvantages of the compositions known from the prior art described above.

[0016] In particular, the aim is to provide masses that are removable and that retain their high bond strength and durability throughout the life cycle of the device or component in which they are used, even under thermal stress or exposure to media.

[0017] These objects are achieved according to the invention by the use of a curable mass according to claim 1, a curable mass according to claim 8, a method for producing a component using the mass according to claim 9 and a component obtainable by the method according to claim 10.

[0018] Advantageous embodiments of the composition according to the invention are specified in the subclaims, which can optionally be combined with one another.

[0019] According to the invention, a hardenable mass comprising the following components is used to produce a component with a thermomechanically removable joint, a coating or a potting compound:

[0020] (a) at least one epoxy compound comprising at least one di- or higher-functional aromatic epoxide;

[0021] (b) at least one hardener suitable for epoxy curing, preferably a nitrogen-based hardener;

[0022] (c) optionally an accelerator for epoxy curing;

[0023] (d) at least one polymeric filler in a proportion of 15% by weight or more, based on the total weight of the composition, wherein the polymeric filler is selected from the group of polyamides;

[0024] (e) optionally one or more compounds curable by radical polymerization; (f) optionally at least one initiator for the radical polymerization; and

[0025] (g) optionally further additives,

[0026] The polymeric filler is present in the mass as at least a semi-crystalline solid, with the melting point of the polymeric filler being at least 120 °C.

[0027] The component preferably has a joint. The compositions according to the invention are particularly suitable for bonding magnets, preferably for the production of stators and / or rotors for electric motors.

[0028] According to one embodiment, a curable composition according to the invention comprises the following components:

[0029] (a) at least one epoxy compound comprising at least one di- or higher-functional aromatic epoxide;

[0030] (b) at least one nitrogen-based hardener suitable for epoxy curing;

[0031] (c) optionally an accelerator for epoxy curing;

[0032] (d) at least one polymeric filler in a proportion of 20% by weight or more, based on the total weight of the composition, wherein the polymeric filler is selected from the group of polyamides;

[0033] (e) optionally one or more radically radiation-curable compounds;

[0034] (f) optionally at least one initiator for radical polymerization; and

[0035] (g) optionally further additives,

[0036] In this embodiment, the polymeric filler, which is present in the composition as an at least semi-crystalline solid, has a melting enthalpy of 40 J / g or more, preferably 50 J / g or more. The melting point of the polymeric filler is at least 120°C. The composition according to the invention is characterized by redetachability at a predetermined temperature, at which a significant decrease in modulus and thus a significant loss of strength can be observed in the DMTA curve of the storage modulus of the cured composition. At the same time, the cured compositions exhibit a high degree of crosslinking and a high glass transition temperature. This ensures a low decrease in strength under thermal stress and good media resistance.

[0037] According to a further aspect, the invention relates to a method for producing a component using the curable composition as described above, the method comprising the following steps: a) Dosing the composition onto a first substrate; b) Optionally feeding a second substrate to form a substrate composite, wherein the second substrate is brought into contact with the composition; c) Optionally irradiating the composition with actinic radiation, wherein the irradiated composition achieves a fixing strength which is sufficient for further processing of the first substrate or the substrate composite;and d) heating the optionally irradiated mass on the substrate or in the substrate composite to a predetermined curing temperature until curing, forming the component with the substrate and a cured adhesive layer bonded to the substrate and optionally to the further substrate, wherein the cured adhesive layer is thermomechanically detachable from the substrate by heating to at least one detachment temperature;

[0038] Preferably, the component comprises a substrate composite with at least two substrates connected by the adhesive layer.

[0039] The storage modulus (E') of the cured mass, measured as a function of temperature by Dynamic Mechanical Thermal Analysis (DMTA), has at least one further inflection point above the glass transition temperature in the curve. The further inflection point lies within a temperature range in which a steep and pronounced drop in the storage modulus and the strength of the cured mass can be observed. The difference between the end set and onset of the temperature range encompassing the further inflection point, i.e. between the end set and onset of the modulus drop, is preferably at most 30 °C, more preferably at most 20 °C or at most 15 °C. The modulus drop in the DMTA curve particularly preferably occurs over a temperature interval of 10 °C or less. The absolute temperature of the further inflection point in the DMTA curve can be influenced by the selection of the semi-crystalline polymeric filler.

[0040] The detachment temperature at which the adhesive layer can be thermomechanically detached from the substrate or substrate composite is preferably selected so that it lies at or above the further inflection point of the DMTA curve of the storage modulus of the cured mass. More preferably, the detachment temperature lies in a range between the temperature at the further inflection point and up to 50°C, more preferably up to 20°C, above the final set of the module waste. Those skilled in the art will appreciate that the adhesive layer can also be removed at higher temperatures. However, the closer the detachment temperature is to the final set of the module waste, the more energy-efficient the recovery of the valuable substrates can be.

[0041] In preferred embodiments, the stripping temperature is at most 320°C, preferably at most 280°C, and particularly preferably at most 250°C. At higher temperatures, there is a risk of thermal damage to the components to be recovered. Furthermore, such high temperatures offer little energy advantage over pyrolysis.

[0042] The invention further relates to a component with a removable adhesive layer, which is obtainable by the method described above. DESCRIPTION OF THE DRAWING

[0043] The drawing shows:

[0044] - Figure 1 shows a DMTA curve showing the storage modulus as a function of temperature for a reference mass and two masses used according to the invention.

[0045] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0046] The invention is described in detail and by way of example below with reference to preferred embodiments, which, however, are not to be understood in a limiting sense.

[0047] In the context of the invention, “liquid” means that at 23 °C the loss modulus G” determined by viscosity measurement is greater than the storage modulus G' of the component in question.

[0048] Where the indefinite article “ein” or “eine” is used, this also includes the plural form “ein or mehr” unless this is expressly excluded.

[0049] "At least difunctional" means that each molecule contains two or more units of the respective functional group. No distinction is made between primary, secondary, or tertiary functional groups.

[0050] All weight proportions listed below refer to the total weight of all components, unless otherwise stated.

[0051] The compositions according to the invention can be formulated as single-component or multi-component compositions.

[0052] Component (a): Epoxy compound

[0053] The epoxy compound (a) is not further restricted in its chemical structure and comprises at least one difunctional or higher-functional aromatic epoxide. The use of aromatic epoxy compounds leads to masses with a high glass transition temperature that remain mechanically stable under thermal stress and exhibit high media resistance.

[0054] Aromatic glycidyl ethers, glycidyl esters, glycidylamines, and mixtures thereof are preferably used. Furthermore, aliphatic and cycloaliphatic epoxy compounds or monofunctional epoxy compounds may also be present as reactive diluents in component (a).

[0055] Aromatic glycidyl ethers are obtained from the reaction of epichlorohydrin with aromatic alcohols and phenols. Examples of such aromatic epoxy compounds and their respective trade names are bisphenol A epoxy resins (DER 331, Epikote Resin 828), bisphenol F epoxy resins (Epikote Resin 862, Epikote Resin 863, YDF-170), mixtures of bisphenol A and F diglycidyl ethers (DER 351, Epikote Resin 166, YDF-161), phenol novolak epoxy resins (DEN 424, DEN 437, DEN 440, YDPN-631), and cresol novolak epoxy resins (DIC Corporation Epikote N-670, YDCN-500-5P).

[0056] Furthermore, glycidyl ethers based on aromatic phenols such as 1,6-naphthalenediol (Araldite MY 0816), tris(hydroxyphenyl)methane (Tactix 742), various bisphenols, hydroxy-substituted biphenyls (e.g. jER YX4000H) or monofunctional glycidyl ethers, e.g. based on p-tert-butylphenol (DER 727) or cardanol (Cardolite Lite 513), can be used.

[0057] Additionally, diglycidyl ethers based on aliphatic alcohols can be used, such as butanediol (Araldite DY-D), hexanediol (Araldite DY-H), cyclohexanedimethanol (Araldite DY-C), polymeric diols (e.g., polyoxypropylene glycol, Araldite DY-F), and dicylopentadienedimethanol (Adeka EP 4088S). Furthermore, the use of reaction products of epichlorohydrin and amines or aminophenols, such as TGAP (triglycidyl ether of aminophenol; Araldite MY 0610) or TGMDA (tetraglycidyl ether of methylenedianiline, Araldite MY 721), is possible.

[0058] Furthermore, all fully or partially hydrogenated analogues of aromatic epoxy compounds can be used. Hydrogenated bisphenol A and bisphenol F epoxy resins (e.g., Eponex Resin 1510) are preferred. Glycidyl esters based on aromatic compounds such as terephthalic acid (ARALDITE® PT 910, Huntsman), cycloaliphatic compounds, or aliphatic compounds (Cardura E10, Westlake) can also be used.

[0059] In addition to the epoxy compounds mentioned above, cycloaliphatic epoxides can also be used in the compositions according to the invention. Suitable examples are 3-cyclohexenylmethyl-3-cyclohexylcarboxylate diepoxide, 3,4-epoxycyclohexylalkyl-3',4'-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3',4'-epoxy-6-methylcyclohexanecarboxylate, vinylcyclohexene dioxide, bis(3,4-epoxycyclohexylmethyl)adipate, dicyclopentadiene dioxide, dicyclopentadienyloxyethyl glycidyl ether, limonene dioxide, and 1,2-epoxy-6-(2,3-epoxypropoxy)hexahydro-4,7-methanindane, as well as mixtures thereof.

[0060] Furthermore, epoxidized compounds based on fats / oils such as Sovermol 1055, BASF can be used.

[0061] Isocyanurates substituted with epoxide-containing groups and other heterocyclic compounds can also be used as component (a) in the compositions of the invention. Examples include triglycidyl isocyanurate and monoallyldiglycidyl isocyanurate.

[0062] In addition, mono- and polyfunctional epoxy resins from all of the above-mentioned resin groups can be used, which contain additional functional groups in addition to the epoxy functionalities. Examples include OH-functional, oligomeric aromatic epoxy compounds (e.g., Dow DER 671 or Kukdo KD-9004).

[0063] Addition products of the aforementioned epoxy compounds with H-acidic compounds (in low molecular weight or polymeric form) such as carboxylic acids, alcohols, and / or thiols can also be used. Particularly preferred examples are reactive liquid rubbers, e.g., addition products of epoxy compounds with CTBN rubber (e.g., Albipox 2000) or dimer fatty acids (e.g., B-Tough A1).

[0064] Also within the scope of the invention is a combination of several epoxy-containing compounds, at least one of which is difunctional or more highly functional. Furthermore, in addition to all of the epoxy-containing compounds mentioned, sulfur analogues can also be used as component (a). The corresponding thiiranes are thus also within the scope of the invention. Epoxides in which only some of the epoxy groups have been replaced by thiiranes can also be used advantageously.

[0065] Component (a) is present in the composition according to the invention, based on the total weight of the composition, preferably in a proportion of 10 to 80 wt.%, more preferably 20 to 70 wt.%.

[0066] Monofunctional epoxy compounds may be present in component (a) in a proportion of up to 30%, based on the weight of component (a).

[0067] Component (b): Hardener for the epoxy compound

[0068] The compositions according to the invention contain at least one hardener (b) for epoxy curing. Component (b) is not further restricted in its chemical structure and preferably comprises a nitrogen-based hardener, more preferably a hardener from the group of primary, secondary, and tertiary amines, cyanamides, imidazoles, hydrazides, and / or epoxy adducts of the aforementioned compounds. The hardener is preferably present in the compositions in solid form.

[0069] Commercial examples of suitable solid amine hardeners containing primary, secondary, and / or tertiary amine groups are Ancamine 2014 AS (Evonik), Ancamine 2337S (Evonik), Ajicure PN-23J (Ajinomoto), Aradur 9506 (Huntsman), FUJICURE FXR-1121 (Sanho), FUJICURE FXR-1020 (Sanho), Hardener XB 3123 (Huntsman), Versalink 740M (Evonik), Lonzacure M-CDEA, Primacure M-DEA, Aradur 9664-1 (Huntsman), and Aradur 9719-1 (Huntsman). These hardeners preferably each contain at least two nitrogen-containing groups suitable for epoxy curing per molecule.

[0070] Commercial examples of suitable cyanamide hardeners are Dyhard 100 SF from Alzchem, DICYANEX 1200 from Evonik, and EPIKURE Curing Agent P-104 from Westlake. Commercial examples of suitable solid imidazole hardeners are Adeka Hardener EH-5011S, Adeka Hardener EH-5046S, Technicure LC-80 (ACCI Specialty Materials), and Curezol 2P4MZ (Shikoku).

[0071] Commercial examples of suitable hydrazides are Technicure ADH-J (ACCI Specialty Materials), Technicure IDH-J (ACCI Specialty Materials), Ajicure LIDH-J (Ajinomoto) and Ajicure VDH-J (Ajinomoto).

[0072] By combining different hardeners (b), epoxy curing can be accelerated even without the addition of component (c). Commercial examples of nitrogen-containing compounds that accelerate curing, especially in combination with another hardener (b), are Ancamine 2014 AS (Evonik), Ancamine 2337S (Evonik), Ajicure PN-23J (Ajinomoto), Aradur 9506 (Huntsman), FUJICURE FXR-1121 (Sanho), FUJICURE FXR-1020 (Sanho), Hardener XB 3123 (Huntsman), Adeka Hardener EH-5011S, Adeka Hardener EH-5046S, and Technicure LC-80 (ACCI Specialty Materials).

[0073] In the case of two- or multi-component compositions, liquid amines from the group consisting of aliphatic or cycloaliphatic amines, polyetheramines, polyamides, Mannich bases, or their reaction products with epoxy resins, as well as combinations thereof, are particularly suitable for use as component (b). These exhibit higher reactivity even at room temperature and can cure component (a) after mixing without additional heat. Specific examples of suitable amines can be found in DE 10 2018 121 067 A1.

[0074] The above lists are to be considered exemplary and not exhaustive. Mixtures of the above-mentioned hardeners (b) are also within the scope of the invention.

[0075] Anhydrides and thiols can also be used as hardeners (b) for epoxy curing.

[0076] Specific examples of anhydrides that can be used as curing agents for epoxies in the present compositions include the anhydrides of diprotic acids, such as phthalic anhydride (PSA), succinic anhydride, octenylsuccinic anhydride (OSA), pentadodecenylsuccinic anhydride and other alkenylsuccinic anhydrides, maleic anhydride (MA), itaconic anhydride (ISA), tetrahydrophthalic anhydride (THPA), hexahydrophthalic anhydride (HHPA), methyltetrahydrophthalic anhydride (MTHPA), methylhexahydrophthalic anhydride (MHHPA), nadic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, methylenedomethylenetetrahydrophthalic anhydride (METH, NMA), tetrabromophthalic anhydride and trimellitic anhydride, as well as the anhydrides of aromatic quadriprotic acids, such as biphenyltetracarboxylic dianhydrides, naphthalenetetracarboxylic dianhydrides, Diphenyl ether tetracarboxylic acid dianhydrides,

[0077] Butanetetracarboxylic dianhydrides, cyclopentanetetracarboxylic dianhydrides, pyromellitic anhydrides, and benzophenonetetracarboxylic dianhydrides. These compounds can be used alone or in combinations of two or more of them.

[0078] Among these anhydrides, compounds that are liquid at room temperature, such as methylhexahydrophthalic anhydride (MHHPA), methyltetrahydrophthalic anhydride (MTHPA), methylenedomethylenetetrahydrophthalic anhydride (METH, NMA) and its hydrogenation product, are preferably used as hardener (b).

[0079] The preferred anhydrides for use as curing agents (b) are commercially available, for example, under the following trade names: MHHPA, for example, under the trade names HN-5500 (Hitachi Chemical Co., Ltd.) and MHHPA (Dixie Chemical Company, Inc.), METH under the trade names NMA (Dixie Chemical Company, Inc.), METH / ES (Polynt SpA) and MHAC (Hitachi Chemical Co., Ltd.).

[0080] When using a hardener (b) for epoxides based on thiols, it comprises at least one compound with at least two thiol groups (-SH) in the molecule. The thiols are not further restricted in their chemical structure and preferably include aromatic and aliphatic thiols, as well as combinations thereof.

[0081] Preferably, the at least difunctional thiol is selected from the group consisting of ester-based thiols, polyethers with reactive thiol groups, polythioethers, polythioether acetals, polythioether thioacetals, polysulfides, thiol-terminated urethanes, thiol derivatives of isocyanurates and glycoluril, and combinations thereof. Examples of commercially available ester-based thiols based on 2-mercaptoacetic acid include trimethylolpropane trimercaptoacetate,

[0082] Pentaerythritol tetramercaptoacetate and glycol dimercaptoacetate, available under the brand names Thiocure™ TMPMA, PETMA and GDMA from Bruno Bock.

[0083] Other examples of commercially available ester-based thiols include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), glycol di(3-mercaptopropionate) and tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate, which are available under the brand names Thiocure TMPMP, PETMP, GDMP and TEMPIC from Bruno Bock.

[0084] Examples of commercially available thioethers include DMDO (1,8-dimercapto-3,6-dioxaoctane), available from Arkema SA, DMDS (dimercaptodiethyl sulfide) and DMPT (2,3-di((2-mercaptoethyl)thio)-1-propanethiol), both available from Bruno Bock.

[0085] With regard to increased resistance of the cured compounds to temperature and humidity, the use of ester-free thiols is particularly preferred. Examples of ester-free thiols can be found in JP 2012 153 794 A.

[0086] Particularly preferred is the use of tris(3-mercaptopropyl)isocyanurate (TMPI) as trifunctional ester-free thiol.

[0087] Ester-free thiols based on a glycoluril compound are known from EP 3 075 736 A1. These can also be used as hardeners (b), alone or in a mixture with other at least difunctional thiols.

[0088] Higher functional thiols, which are obtainable, for example, by oxidative dimerization processes of at least difunctional thiols, can also be used.

[0089] The above list is to be seen as exemplary and not exhaustive.

[0090] The proportion of hardener (b) in the composition according to the invention is preferably 1 to 50 wt. %, more preferably 2 to 30 wt. %. Component (c): Accelerator

[0091] At least one accelerator (c) for epoxy curing can optionally be used in the compositions according to the invention. This accelerator is selected, for example, from the group of urea derivatives, amines, and imidazoles.

[0092] Examples of suitable accelerators based on ureas and their derivatives are ilrones. Commercial examples include Dyhard UR 500 (Alzchem), Dyhard UR 300 (Alzchem), EPICURE Catalyst 116 (Westlake), Technicure MDU-11 M (ACCI Specialty Materials), Technicure IPDU-8 (ACCI Specialty Materials), Technicure MDU-11M (ACCI Specialty Materials), Dyhard UR 800 (Alzchem), URAcc 57 (Alzchem), UR 700 (Alzchem), UR 500 (Alzchem), and EPICURE Catalyst 116 (Westlake).

[0093] Examples of suitable amine-based accelerators are Ancamine 2014 AS (Evonik), Ancamine 2337S (Evonik), Ajicure PN-23J (Ajinomoto), Aradur 9506 (Huntsman), FUJICURE FXR-1121 (Sanho), FUJICURE FXR-1020 (Sanho).

[0094] Examples of suitable imidazole-based accelerators are Adeka Hardener EH-5011S, Adeka Hardener EH-5046S, Technicure LC-80 (ACCI Specialty Materials), Curezol 2P4MZ (Shikoku).

[0095] The accelerators (c) listed here are explicitly understood as additional accelerating compounds that are not included in component (b) and combinations thereof. The use of multiple accelerators is also within the scope of the invention.

[0096] The accelerator (c) is preferably present in the compositions according to the invention in a proportion of 0 to 5% by weight, preferably 1 to 3% by weight, based on the total weight of the composition.

[0097] Component (d): polymeric filler

[0098] The compositions according to the invention contain at least one organic polymer filler (d). This is selected from the group of polyamides and has a melting point of at least 120°C. The polymer filler is present in the composition as an at least semi-crystalline solid in a proportion of 15 wt. % or more, based on the total weight of the composition. A lower proportion of the semi-crystalline polymer filler leads to compositions with insufficient re-removability of the cured composition at the predetermined release temperature. Adhesive layers made from these compositions can only be removed from the respective substrates with greater force.

[0099] The organic filler is preferably selected from the group of polyamide 6, polyamide 6.6, polyamide 11, polyamide 12 and copolymers thereof.

[0100] The melting point of the filler (d) is preferably greater than 120 °C, and is preferably at least 140 °C, more preferably at least 160 °C. The melting point of component (d) is preferably below 300 °C, more preferably below 250 °C. The melting point is considered to be the peak temperature determined in the DSC analysis of the polymeric filler or of the cured mass containing the filler at a heating rate of 10 K / min.

[0101] More preferably, the average particle size D50 of the polymeric filler (d) as determined by laser light diffraction is less than 100 pm, more preferably less than 50 pm.

[0102] Commercially available examples of the polymer filler include Rilsan grades D20, D30, D40, D50, D60, D80, Orgasol 2001, Orgasol 2002, Orgasol 1002, and Orgasol 3501, available from Arkema, as well as Ultrasint PA6 and Ultrasint PA11 from BASF. Commercial granules, such as Ertalon 6 PLA and Ertalon 66 SA from Mitsubishi Chemical Advanced Materials or Zytel 7335F NC010 from DuPont, can be converted to the appropriate particle size distribution by, for example, mechanical grinding.

[0103] Component (d) is selected in each case in the context of the intended application of the cured mass. The melting point of the filler (d) is preferably selected such that it is at least 5 °C, preferably at least 10 °C, above the average temperature to which the cured mass is permanently exposed during its application. For energy-efficient redetachment, a small temperature difference between the onset of the modulus drop in the DMTA curve of the storage modulus and the application temperature of the mass below this onset is also preferred. For applications in which temperature peaks are likely to occur frequently, a higher temperature difference is preferred for reasons of reliability.

[0104] The polymer filler (d) used in the compositions according to the invention has a melting enthalpy of at least 40 J / g, preferably 50 J / g. The melting enthalpy indicates the degree of crystallization of the filler (d) used.

[0105] The proportion of the at least partially crystalline polymeric filler (d) in the composition according to the invention is at least 15 wt. %, preferably at least 20 wt. % or 25 wt. %, but at most 50 wt. %, based in each case on the total weight of the composition. A higher proportion of the at least partially crystalline polymeric filler can result in the liquid curable compositions having a viscosity that is disadvantageous for processing, and in the cured compositions having insufficient temperature stability or media resistance.

[0106] Component (s): radically curable compound

[0107] The compositions optionally contain a compound (e) curable by radical polymerization, which comprises at least one (meth)acrylate. The term "(meth)acrylate" within the meaning of the invention encompasses both acrylates and the analogous methacrylates. The use of component (e) allows for rapid curing of the composition, particularly by irradiation with actinic radiation.

[0108] The (meth)acrylates of component (e) are not further restricted structurally and include, for example, linear, branched, aliphatic, aromatic and heterocyclic (meth)acrylates and combinations thereof.

[0109] (Meth)acrylates within the meaning of the invention are also monomeric, oligomeric or polymeric compounds, as long as they contain at least one radically crosslinkable (meth)acrylate group.

[0110] Preferred are (meth)acrylates whose homopolymer has a glass transition temperature of greater than 100 °C, but at the same time this is below the release temperature of the cured composition according to the invention.

[0111] The masses preferably contain at least one di- or higher-functional (meth)acrylate. Examples of di- or higher-functional (meth) acrylates are hexanediol di(meth)acrylate, di(trimethylolpropane) tetraacrylate, 4-butanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, cyclohexanedimethylol di(meth)acrylate, nonanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tris-(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol hexa(meth)acrylate, dipentaerythritol hexa-(meth)acrylate, BPA-diepoxypropane di(meth)acrylate and ethoxylated bisphenol A di(meth)acrylate.

[0112] The (meth)acrylates mentioned are commercially available from companies such as Arkema Sartomer, BASF, IGM Resins, Sigma Aldrich or TCI.

[0113] In addition to di- or higher-functional (meth)acrylates, monofunctional aliphatic, cycloaliphatic or aromatic (meth)acrylates can also be used.

[0114] Examples of suitable monofunctional (meth)acrylates are isobornyl (meth)acrylate, cyclic trimethylolpropane-formyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, tert-butylcyclohexanol methacrylate and octahydro-4,7-methano-1H-indenylmethyl (meth)acrylate.

[0115] (Meth)acrylates with low solubility with respect to the hardener (b) are preferred. This allows for advantageous latency of the compositions at room temperature.

[0116] Furthermore, hybrid compounds can also be used that contain an addition-curable group in addition to a radiation-curable group. Examples that contain an epoxy group in addition to a (meth)acrylate group are so-called epoxy acrylates such as Solmer SE 1605 available from Soltech Ltd, Cyclomer M100 available from Daicel, RCX 14-786 from Rahn AG, and 4-hydroxybutyl acrylate glycidyl ether available from Mitsubishi Chemical Europe GmbH.

[0117] The above list of suitable substance classes is exemplary and not to be understood in a restrictive sense. Component (e) is present in the compositions according to the invention in a proportion of 0 to 40 wt.%, preferably 1 to 30 wt.%, based in each case on the total weight of the composition.

[0118] The proportion of di- or higher-functional (meth)acrylates in component (e) is preferably at least 50%, more preferably at least 60%.

[0119] Component (f): Initiator for radical polymerization

[0120] To cure component (e), the compositions of the invention optionally comprise at least one initiator (f) for free-radical polymerization. Photoinitiators (f1), in combination with component (e), enable fixation of the composition by irradiation with actinic radiation. Thermal initiators for free-radical polymerization (f2) allow thermal curing of the compound (e). In light-fixable formulations, initiators (f2) can be advantageously used in addition to the photoinitiators (f1) for the complete curing of regions of the curable composition that cannot be reached by actinic radiation.

[0121] As radical photoinitiators (f1) the usual, commercially available compounds can be used, such as, for example, a-hydroxyketones, benzophenone, a,a'-diethoxyacetophenone, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, 4-isopropylphenyl-2-hydroxy-2-propyl ketone, 4,4-bis(diethylamino)benzophenone, 2-ethylhexyl-4-(dimethylamino)benzoate, ethyl-4-(dimethylamino)benzoate, 2-butoxyethyl-4-(dimethylamino)benzoate, 1-hydroxycyclohexylphenyl ketone, isoamyl-p-dimethylaminobenzoate, methyl-4-dimethylaminobenzoate, methyl-o-benzoylbenzoate, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2- Hydroxy-2-methyl-1-phenylpropan-1-one, 2-isopropylthioxanthone,

[0122] Dibenzosuberone, ethyl (3-benzoyl-2,4,6-trimethylbenzoyl)(phenyl) phosphinate, methyl benzoyl formate, oxime ester, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl (2,4,6-trimethylbenzoyl) phenyl phosphinate and bisacylphosphine oxide.

[0123] The radical photoinitiator (f1) is preferably activatable by irradiation with actinic radiation having a wavelength of 200 to 600 nm, particularly preferably 320 to 480 nm. If required, the radical photoinitiator can be combined with a suitable sensitizer. Commercially available photoinitiators that can be used include the IRGACURE™ types from BASF SE, such as IRGACURE 184, IRGACURE 500, IRGACURE 1179, IRGACURE 2959, IRGACURE 745, IRGACURE 651, IRGACURE 369, IRGACURE 907, IRGACURE 1300, IRGACURE 819, IRGACURE 819DW, IRGACURE 2022, IRGACURE 2100, IRGACURE 784, IRGACURE 250, IRGACURE TPO, IRGACURE TPO-L. Furthermore, DAROCUR TM -Types from BASF SE can be used, such as the types DAROCUR MBF, DAROCUR 1173, DAROCUR TPO and DAROCUR 4265.

[0124] The above list of suitable substance classes is exemplary and should not be understood in a restrictive sense.

[0125] Combinations of several photoinitiators are also according to the invention.

[0126] The radical photoinitiator (f1) is preferably present in the compositions according to the invention in a proportion of 0 to 5 wt.%, more preferably 0.1 to 3 wt.%, in each case based on the total weight of the composition.

[0127] Examples of suitable thermal initiators for radical polymerization (f2) are peroxo compounds such as peroxo(di)esters, hydroperoxides, (di)alkyl peroxides, ketone peroxides, perketals, peracids, peroxodicarbonates, peroxomonocarbonates and benzpinacol.

[0128] Beispiele für geeignete Peroxoester umfassen Cumol-peroxyneodecanoat, 1 , 1 ,3,3-T etramethylbutyl-peroxyneodecanoat, tert-Amyl-peroxyneodecanoat, tert- Butyl-peroxyneodecanoat, 1 ,1 ,3,3-Tetramethylbutyl-peroxypivalat, tert-Amyl- peroxypivalat, tert-Butyl-peroxypivalat, Didecanoyl-peroxid, Dilauroyl-peroxid, 2,5- Dimethyl-2,5-di(2-ethylhexanoylperoxy)-hexan, 1 ,1 ,3,3-Tetramethylbutyl-peroxy- 2-ethylhexanoat, tert-Amyl-peroxy-2-ethylhexanoat, Dibenzoyl-peroxid, tert-Butyl- peroxy-2-ethylhexanoat, tert-Butyl-peroxyisobutyrate, tert-Butyl-peroxy-3,5,5- trimethylhexanoat, tert-Butyl-peroxyacetat und tert-Butyl-peroxybenzoat.

[0129] Beispiele für geeignete Hydroperoxide umfassen Di-isopropylbenzol-mono- hydroperoxid, p-Menthanhydroperoxid, Cumolhydroperoxid, 1 ,1 , 3, 3-

[0130] Tetramethylbutyl hydroperoxide, tert-butyl hydroperoxide and tert-amyl hydroperoxide. Examples of suitable alkyl peroxides include diisobutyryl peroxide, di-(3,5,5-trimethylhexanoyl) peroxide, 1,1-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di-(tert-butylperoxy)cyclohexane, 2,2-di-(tert-butylperoxy)butane, di-tert-amyl peroxide, dicumyl peroxide, di-(2-tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne and di-tert-butyl peroxide.

[0131] Examples of peroxodicarbonates include di-(4-tert-butyl-cyclohexyl)-peroxodicarbonate, di-(2-ethylhexyl)-peroxodicarbonate, di-n-butyl-peroxodicarbonate, dicetyl-peroxodicarbonate, dimyristil-peroxodicarbonate and mixtures thereof.

[0132] Examples of suitable peroxomonocarbonates include tert-amyl peroxy-2-ethylhexyl carbonate, tert-butyl peroxyisopropyl carbonate and tert-butyl peroxy-2-ethylhexyl carbonate.

[0133] The peroxo compound (f2) is preferably present in the compositions according to the invention in a proportion of 0 to 10 wt.%, more preferably 0.1 to 5 wt.%, in each case based on the total weight of the composition.

[0134] The thermal initiator (f2) may be present in addition to or instead of the radical photoinitiator (f1).

[0135] Component (g): Additives

[0136] In addition to components (a) to (f), the compositions according to the invention may contain further additives (g). Preferred additives (g) are toughness modifiers such as core-shell particles (Kaneka KaneAce TM-Series, Dow Paraloid™ EXL-Series, Wacker Genioperl®) or block copolymers, reactive elastifiers (e.g. blocked isocyanate prepolymers according to US 5 278 257 A), dyes, pigments, fluorescent agents, thixotropic agents, thickeners, stabilizers, antioxidants, plasticizers, fillers, flame retardants, corrosion inhibitors, inert diluents, catalysts, leveling and wetting additives and adhesion promoters, as well as combinations thereof.

[0137] In addition to the polymeric filler (d), other organic or inorganic fillers not covered by component (d) may be included as additive (g1). These allow, for example, the adjustment of the mechanical, enthalpic, thermal, rheological, and electrical properties of the compositions and can be advantageously used to increase the resistance of the cured composition to temperature, humidity, and media influences.

[0138] Suitable fillers (g1) are, for example, compounds from the group of oxides, nitrides, borides, carbides, sulfides and silicides of metals and semimetals, including mixed compounds of several metals and / or semimetals, carbon modifications such as diamond, graphite and carbon nanotubes, silicates and borates of metals and semimetals, all types of glasses, metals and semimetals in elemental form, in the form of alloys or intermetallic phases and particles of polymeric materials, such as silicone and PTFE.

[0139] To accelerate the heat input required for redissolving the compounds, particularly during irradiation with IR radiators, IR-absorbing dyes, such as those described in EP 3 943 534 A1, can also be advantageously used as additive (g2). These not only enable more efficient input of heat energy into the adhesive layer, but also simultaneously facilitate faster heating and thus redissolving of the cured compound.

[0140] The further additives (g) are present in the compositions according to the invention in a proportion of 0 to 50, preferably 1 - 30 wt.%, based on the total weight of the composition.

[0141] Formulation of the compositions according to the invention:

[0142] According to a preferred embodiment, the composition according to the invention consists of the following components: a) at least one epoxy compound comprising at least one di- or higher-functional aromatic epoxy compound; b) at least one solid nitrogen-based hardener selected from the group of amines, hydrazides, cyanamides, or imidazoles; c) optionally an accelerator for epoxy curing; d) 15-50% by weight of an organic filler selected from the group of polyamides; g) optionally further additives.

[0143] According to a second preferred embodiment, the composition according to the invention consists of the following components, each based on the total weight of components a) to g): a) At least one epoxy compound comprising at least one di- or higher-functional aromatic epoxy compound; b) At least one solid nitrogen-based hardener selected from the group of amines, hydrazides, cyanamides or imidazoles; c) Optionally, an accelerator for epoxy curing; d) 15-50% by weight of an organic filler selected from the group of polyamides, e) 1-30% by weight of a compound curable by radical polymerization and comprising at least one (meth)acrylate; f) At least one initiator for radical polymerization selected from the group of photoinitiators and / or thermal initiators, and; g) Optionally, further additives.

[0144] The compositions of the second embodiment, if they contain at least one photoinitiator for radical polymerization, can also be fixed by irradiation. They are therefore suitable for converting the liquid composition into a dimensionally stable state, in which flow can no longer occur, even before heat curing. This facilitates handling of the composition in subsequent process steps. Instead of or in addition to the use of a photoinitiator, thermal initiators can also be used as component (f). These allow even radically curable components in shadow zones to be fully cured by heating. Curing of the compositions according to the invention

[0145] At temperatures of 100 to 160 °C, the masses can be fully cured within 4 hours, preferably within 2 hours.

[0146] Temperature-graded hardening profiles are also within the scope of the invention.

[0147] The mass can be heated for curing, for example, in convection ovens, by thermodes, IR emitters, lasers, microwaves or induction.

[0148] If the compositions according to the invention are formulated in two or more components, curing can take place at room temperature over a period of up to 7 days, preferably up to 5 days.

[0149] The curing temperature of the compositions according to the invention is preferably selected so that it is below the melting point of component (d). This prevents melting of the semi-crystalline polymeric filler (d) during curing.

[0150] The fusion enthalpy of the cured mass determined by DSC measurement is preferably at least 10 J / g, more preferably at least 20 J / g.

[0151] Use of the compositions according to the invention

[0152] The compositions according to the invention are suitable for producing removable bonds, coatings, and encapsulations. The compositions are particularly suitable for components that are exposed to high mechanical and thermal stresses, both permanently and periodically, during their normal operation. The cured compositions are characterized by their high strength and durability, yet are simultaneously removable at elevated temperatures. Components joined using the composition can be removed again by heating to a predefined temperature with only a small amount of force. The removal temperature is preferably at or above the further inflection point in the DMTA curve of the storage modulus of the cured composition.

[0153] For example, the masses can be used to manufacture electric motors (e-motors). Specifically, magnets in electric motors can be bonded using the masses. Especially in high-performance electric motors, the magnets contain rare earth metals, the recovery of which is often of great economic interest. At the same time, the masses are exposed to high temperatures over the service life of an electric motor and, depending on the application, to stresses from media such as dust, oils, greases, coolants, lubricants, or solvents. The masses of the present invention withstand these stresses even over long periods of operation.

[0154] Further applications in which the compositions according to the invention can be used advantageously include structural bonding in automotive applications in the drive train sector, but also, for example, joining or potting applications in the chip industry.

[0155] In principle, the masses are always suitable for applications in which very high-priced components are used, the disposal of which represents a major economic loss.

[0156] If the hardened mass is to be detached from a component or from a substrate composite, it is advantageous to select detachment temperatures that are at or above the temperature at the further inflection point in the DMTA curve of the storage modulus of the hardened mass.

[0157] The separation temperature preferably lies in a range between the temperature at the further inflection point and up to 50°C, more preferably up to 20°C, above the final set of the module waste. In preferred embodiments, the separation temperature is at most 320°C, preferably at most 280°C, and particularly preferably at most 250°C. At higher temperatures, there is a risk of thermal damage to the components to be separated.

[0158] The heat required to reach the release temperature can be applied, for example, using an oven, induction, laser, microwaves, thermodes or infrared radiators.

[0159] The duration of heat application varies depending on the heat generation method, the size and nature of the components, the amount of material to be removed, and the heat accessibility of the adhesive layer. Especially for large components made of metallic materials, heat application can be achieved quickly and efficiently using alternating inductive fields.

[0160] Above the temperature at the further inflection point in the DMTA storage modulus curve, the joints can be released from the hardened mass using low mechanical forces, allowing the components to be separated. A low residual strength of the hardened mass, even when heated to temperatures above the separation temperature, ensures that large components in particular do not detach from each other in an uncontrolled manner.

[0161] To keep the necessary force input into the components low, the lowest possible storage modulus of the cured masses would be advantageous. However, this conflicts with the requirements for strong and durable bonding, even under high thermal and mechanical loads. To meet both requirements, the cured masses in the DMTA curve preferably exhibit a drop in storage modulus of at least 30%, more preferably at least 45%, between the onset and endset of the temperature range encompassing the further inflection point, above the glass transition temperature.

[0162] A smaller decrease in the storage modulus may also occur due to temperature-induced softening of the cured mass. However, this decrease is essentially continuous over a wide temperature range and does not represent a turning point within the meaning of the invention. Efficient thermomechanical re-removability is only sufficiently achieved with the use of the polymeric filler (d).

[0163] Below the temperature at the further inflection point, the joints produced using the compositions according to the invention exhibit high strength, particularly tensile shear strength, and high resistance to mechanical, thermal, and chemical stress. Only when the temperature at the further inflection point is exceeded and / or the detachment temperature is reached does an almost sudden drop in strength occur. Joining or coating processes using the compositions according to the invention

[0164] A method for producing a component using a curable composition according to the invention preferably comprises the following steps: a) Dosing the composition onto a first substrate; b) Optionally feeding a second substrate to form a substrate composite, wherein the second substrate is brought into contact with the composition; c) Optionally irradiating the composition with actinic radiation to achieve a fixing strength sufficient for further processing of the first substrate or the substrate composite; and d) Heating the optionally irradiated composition on the substrate or in the substrate composite to a predetermined curing temperature until curing, forming the component with the substrate and a cured adhesive layer bonded to the substrate and optionally to the further substrate, wherein the adhesive layer can be thermomechanically detached from the substrate by heating to a predetermined detachment temperature.

[0165] To ensure sufficient dosing capability, the masses are preferably liquid at room temperature and typically have a viscosity between 10 and 700 Pa*s.

[0166] If the application requires it, either the first or second substrate can be aligned relative to the other after joining in step b) before fixing by irradiation of the mass.

[0167] In a further preferred embodiment, the compound is used in a so-called B-stage process. Here, the dispensing of the compound onto the first substrate and the supply of a second substrate can be carried out at different times and locations by fixing the compound with actinic radiation after application to the first substrate. The flowability is restricted by the fixing step to such an extent that no further changes to the dispensing pattern on the component occur. In a subsequent step, the substrate can be joined to another substrate and then fully cured by heating.

[0168] Suitable masses for such a process can be obtained by the second preferred embodiment.

[0169] Properties of the hardened masses

[0170] The cured compounds based on aromatic epoxy compounds not only offer removability from bonded, coated, or cast substrates, but also offer high resistance to media, temperature, and humidity. At the same time, they exhibit high bond strength even under thermal stress.

[0171] The cured masses achieve tensile shear strengths on metals such as aluminum or steel of at least 5 MPa at room temperature and at least 3 MPa at the operating temperatures encountered in the application.

[0172] The modulus of elasticity of the cured masses is preferably greater than 100 MPa, preferably greater than 150 MPa.

[0173] The glass transition temperature of the cured masses is preferably at least 80 °C, preferably at least 100 °C, particularly preferably at least 120 °C. A high glass transition temperature ensures a low loss of strength even at elevated temperatures.

[0174] According to the invention, the cured masses are removable at a predetermined release temperature, preferably at or above the temperature at the further inflection point in the DMTA curve of the storage modulus. At this release temperature, the tensile shear strength of the cured masses on steel is preferably at most 2 MPa, more preferably at most 1 MPa.

[0175] The at least semi-crystalline polyamides used as filler (d) have a relatively narrow melting range. As a result, the strength drop of the cured mass also occurs within a narrowly defined temperature interval as soon as the onset of the modulus drop in the DMTA storage modulus curve is exceeded. The release temperature of the mass can thus be reliably adjusted and adapted to the respective application by selecting the filler (d). The storage modulus of the cured mass, measured as a function of temperature, has at least one further inflection point above the glass transition temperature in the Dynamic Mechanical Thermal Analysis (DMTA) curve. This inflection point lies within a temperature range in which a steep and pronounced drop in the storage modulus and the strength of the cured mass occurs.

[0176] In addition to the step occurring at the glass transition temperature, the addition of the at least semi-crystalline polyamide thus creates a further step in the storage modulus of the cured composition. Upon heating above the temperature at the further inflection point, this step is exceeded, and a significant decrease in the storage modulus occurs in the compositions used according to the invention. In particular, the drop in the storage modulus between the onset and endset of the temperature range encompassing the further inflection point is at least 30%, more preferably at least 45%.

[0177] In a comparable temperature range, the tensile shear strength of a steel-to-steel bond with the compounds used according to the invention is also reduced, so that above the temperature at the further inflection point, significantly less force is required to detach the adhesive layer. At the same time, the at least semi-crystalline polyamide as filler (d) does not negatively affect the glass transition temperatures of the cured compounds and the tensile shear strengths at room temperature.

[0178] Measurement methods and definitions used

[0179] Irradiation

[0180] For irradiation, the compositions according to the invention were irradiated with an LED lamp DELOLUX 20 / 365 from DELO Industrie Klebstoffe GmbH & Co. KGaA at a wavelength of 365 nm with an intensity of 200 ± 20 mW / cm 2 irradiated for a duration of 60 s.

[0181] Curing

[0182] "Crosslinking" or "curing" is defined as a polymerization or addition reaction beyond the gel point. The gel point is the point at which the storage modulus G' equals the loss modulus G" in an oscillating rheology measurement. The compounds were cured in a convection oven for 40 minutes at 150 °C.

[0183] Room temperature

[0184] Room temperature is defined as 23 ± 2 °C.

[0185] Assessment of light fixation

[0186] To assess light fixation (solid vs. liquid), the materials are visually assessed. Optionally, a tactile test is performed using a plastic spatula.

[0187] Viscosity determination

[0188] The viscosity was measured using a Physica MCR302 rheometer from Anton Paar with a standardized PP20 measuring cone at 23 °C with a 500 pm gap and determined at a shear rate of 10 / second.

[0189] Determination of melting point and enthalpy of fusion

[0190] The enthalpy of fusion and the melting point were determined using differential scanning calorimetry (DSC) on a Mettler Toledo "DSC2" in accordance with DIN EN ISO 11357-3:2018-07. The melting point is defined as the temperature at the maximum of the largest endothermic peak of the respective measurement run. Al crucibles with a volume of 40 μl and perforated lids were used. The measurements on the semi-crystalline polymeric fillers (d) were carried out in the range from 30 °C to 280 °C at a heating rate of 10 K / min under nitrogen. Deviating from the standard, the melting point and enthalpy were determined in the first heating run. To measure the melting point and enthalpy of fusion of the cured masses, they were first cured for 40 minutes at 150 °C in a convection oven. Optionally, irradiation was carried out beforehand.The measurement was carried out in an Al crucible with a volume of 40 pl with a perforated lid, under air in a temperature range of 0 °C to 250 °C with a heating rate of 10 K / min.

[0191] Tensile shear strength at room temperature (aluminum test specimen)

[0192] The tensile shear strength was determined at room temperature in accordance with DIN EN ISO 1465:2009-07. Test specimens measuring 100 mm long, 25 mm wide, and 1.6 mm thick were used, bonded with an overlap of 12.5 mm and an adhesive layer thickness of 0.1 mm. The test speed was 10 mm / min. The test was conducted at room temperature on a Zwick Roell "AllroundLine 20 kN" universal testing machine. The curing time was 40 minutes at 150 °C plus the heating time. Aluminum-clad and corundum-blasted AlMgCu specimens were used as test specimens.

[0193] Tensile shear strength at elevated temperatures (steel test specimen)

[0194] The tensile shear strength at elevated temperature (temperature strength) was determined in accordance with DIN EN 14869-2:2004-10. The length of the test specimens was 50 mm instead of 57.5 mm for the long side and 30 mm instead of 51 mm for the short side, deviating from the standard. The thickness of the test specimens was 15 mm instead of 12 mm. The bond overlap length was 10 mm. The adhesive layer thickness was 0.3 mm. The test speed was 10 mm / min at the specified test temperature. The test was carried out at the specified temperature on a Zwick Roell "AIIRoundLine" testing machine. The curing time was 40 minutes at 160 °C plus a 45-minute heat-up time. The test specimens were made of corundum-blasted steel (S235).

[0195] Determination of the glass transition temperature (T G ) and the memory module

[0196] The determination of the dynamic mechanical properties of the cured masses was carried out by Dynamic Mechanical Thermal Analysis (DMTA) in accordance with ISO 6721. The curing of the test specimens with the dimensions 40x5x0.5 mm 3 The test was carried out for 40 minutes at 150 °C in a suitable plastic mold. The glass transition temperature is defined as the value at which the first derivative of the storage modulus (E') reaches its maximum (inflection point, see ISO 6721-11:2012, Section 3.1). The storage modulus for the respective temperatures was determined according to ISO 6721-4:2008. The measurement was carried out in a temperature range of 0 - 300 °C with a heating rate of 1 K / min at a frequency of 1 Hz with an amplitude of 30 pm. A Netzsch DMA 242E was used as the measuring instrument.

[0197] The particle size distribution was determined using a Microtrac S3500 particle size analyzer by laser light diffraction in accordance with ISO 13320. The distribution indicated with the size D50 refers to the mean volumetric particle diameter.

[0198] Production of the hardenable masses

[0199] To produce the curable compounds used in the following examples, the liquid components are first mixed, followed by the fillers and optionally other solids, using a laboratory stirrer, laboratory dissolver, or a speed mixer (Hauschild) until a homogeneous compound is formed. Compounds containing photoinitiators and sensitive to visible light must be produced under light outside the excitation wavelength of the photoinitiators or sensitizers.

[0200] The following list shows all the compounds used to produce the curable masses and their abbreviations:

[0201] Component (a): Epoxy compound

[0202] (a1) Epikote Resin 169 (mixture of bisphenol A and bisphenol F diglycidyl ethers; available from Westlake);

[0203] (a2) Kane ACE MX 257 (rubber particles dispersed in bisphenol A diglycidyl ether; available from Kaneka)

[0204] (a3) Tactix 742 (triglycidyl ether of tris(hydroxyphenyl)methane; available from Huntsman)

[0205] (a4) Epilox P 13-21 (1,4-butanediol diglycidyl ether; available from Leuna Harze)

[0206] (a5) Epikote Resin 828 LVEL (low-chlorine bisphenol A resin; available from Westlake); component (b): nitrogen-based hardener

[0207] (b1) Epikure Curing Agent 921 Super SH (dicyandiamide; available from Westlake)

[0208] (b2) Ancamine 2014 FG (amine-based solid hardener; available from Evonik)

[0209] (b3) Technicure IDH-J (isophthalic acid dihydrazide; available from ACCI Specialty Materials)

[0210] (b4) Adeka Hardener EH-5011S (imidazole-based solid hardener; available from Adeka)

[0211] Component c): Accelerator

[0212] (c1): DYHARD UR 500 (Uron-based accelerator, available from Alzchem)

[0213] Component (d): Fillers

[0214] (d1): Orgasol 1002 D NAT 1 (polyamide 6; available from Arkema), melting range DSC (10 K / min) 205 °C (onset) via 214 °C (peak) to 220 °C (endset) with an enthalpy of 116 J / g

[0215] (d2): Rilsan PA11 D30 NAT (Polyamide 11; available from Arkema) Melting range DSC (10 K / min) 180 °C (onset) over 190 °C (peak) to 194 °C (endset) with an enthalpy of 85 J / g

[0216] Component (s): radically curable compound

[0217] (e1): Photomer4006 (trimethylolpropane triacrylate; available from IGM Resins)

[0218] Component (f): Initiator for radical polymerization

[0219] (f1): Genocure TPO-L (photoinitiator available from Rahn AG)

[0220] Component (g): Other additives

[0221] (g1): Cab-O-Sil TS-720 (rheology additive; available from Cabot Corporation) (g2): Ulmer Weiss XMF (micronized chalk filler; available from Eduard Merkle GmbH & CO. KG)

[0222] (g3): Elvacite 2614 (micronized methacrylate copolymer; available from Mitsubishi Chemical Corporation) (g4): Dynasylan GLYMO (adhesion promoter; available from Evonik)

[0223] The composition of the curable masses thus produced and the properties measured on these masses are given in the following tables.

[0224] Table 1 : Composition of the curable masses

[0225] Example Cl VI V2 C2 V3 V4 C3 V5 V6 V7

[0226] component

[0227] (al) 39.5 39.5 39.5 39.5 57.5 10.0 41.4 41.4 39.5 41.4

[0228] (a2) 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0

[0229] (a3) 7.2 7.2 7.2 7.2 4.8 7.2

[0230] (a4) 2.0 2.0 2.0 2.0 2.0

[0231] (a5) 12.7

[0232] (bl) 4.4 4.4 4.4 4.4 5.0 3.0 3.0 4.4 3.0

[0233] (b2) 10.0 10.0 10.0

[0234] (b3) 16.0

[0235] (b4) 1.0

[0236] (cl) 1.3 1.3 1.3 1.3 1.5 1.3

[0237] (dl) 20.0 35.0 35.0 30.0 35.0

[0238] (d2) 35.0 35.0

[0239] (el) 13.0

[0240] (fl) 1.0

[0241] (gl) 0.6 0.6 0.6 0.6 1.0 0.6 0.6 0.6 0.6 0.6

[0242] (g2) 35.0 15.0 35.0

[0243] (g3) 35.0

[0244] (g4) 0.9

[0245] Table 2: Mechanical-thermal properties of the cured masses

[0246] Measurement of measured variable Cl VI V2 C2 V3 V4 C3 V5 V6 V7

[0247] DMTA, train Tg (first turning point E') 134 127 132 86 121 152 120 117 133 124 [°C]

[0248] T (Onset module drop) [°C] nb 187 192 nb 201 190 nb 196 172 172

[0249] T (further turning point) nb 190 195 nb 204 193 nb 199 174 174

[0250] [°C]

[0251] T (Endset module waste,) [°C] nb 196 201 nb 211 200 nb 204 179 180

[0252] E' (23°C) [MPa] 3990 2530 2900 4243 2697 3390 4560 2890 1783 2200

[0253] E' (Onset) [MPa] nb 41 29 nb 31 183 nb 54 61 79

[0254] E' (end set) [MPa] nb 21 9 nb 6 75 nb 17 14 19

[0255] Decrease E' between onset- nb 49 69 nb 81 59 nb 69 77 76 endset [%]

[0256] DSC melting point [°C] 212 - - . . . 187

[0257] (hardened mass) Enthalpy of fusion [J / g] 42 - - - - - 33 (hardened mass) Lap shear strength Al / Al @ RT [MPa] 21.4 22.2 20.1 nbnb 15.9 18.2 18.8

[0258] Temperature strength (St / St) [MPa] 180°C 8.03 3.7 1.54 23.3 25.2

[0259] (St / St) [MPa] 220°C 5.67 1.17 1.54 Decrease [%] 29 68 0

[0260] Temperature resistance 180 °C after 1000h 180°C 7.25 5.12 after thermal

[0261] Storage

[0262] 220°C after 1000h 180°C 5.26 1.4

[0263] Decrease [%] TI 73

[0264] Inventive examples V1 and V2 contain a semi-crystalline polyamide as filler (d) with a melting point of 214 °C, defined as the peak temperature of the DSC measurement. The addition of the semi-crystalline polymer creates a further step in the DMTA curve of the storage modulus of the composition, which has a further inflection point above the glass transition temperature. In the case of examples V1 and V2, the further inflection point is at 190 °C and 195 °C, respectively. Heating the composition beyond the further inflection point exceeds this step. In inventive examples V1 and V2, a decrease in the storage modulus of 49% and 69%, respectively, occurs in the temperature range between the onset and endset of the modulus decrease.

[0265] Comparative Example C1 contains no polymeric filler. The DMTA curve of the storage modulus of Comparative Example C1 exhibits no further inflection point above the glass transition temperature. Therefore, the compound C1 is not suitable for producing a thermomechanically removable joint within the meaning of the invention.

[0266] In the temperature range between 180 °C and 220 °C, the tensile shear strength in a steel-to-steel bond made with the inventive compound V2 is reduced by 68%, while the tensile shear strength of the compound from Comparative Example C1 drops by only 29%. V2 has a high temperature strength of 3.7 MPa at 180 °C, whereas at 220 °C the temperature strength is only 1.17 MPa. The temperature strength at 220 °C of the compound from Example V2 is thus 4.8 times lower than that of Comparative Example C1. A joint produced with the compound from Example V2 therefore requires significantly less force during thermomechanical redetachment than a joint made with the compound from Comparative Example C1. Furthermore, the polymeric filler (d) does not negatively influence the glass transition temperatures of the cured compounds and the tensile shear strengths at room temperature.The compositions according to the invention are thus resistant to thermal and mechanical stress.

[0267] The composition from Comparative Example C2 contains an amorphous polymer as a filler. The use of an amorphous filler (g3) instead of a semi-crystalline polymer filler (d) does not result in any additional decrease in the storage modulus. In the DMTA measurement, no further inflection point occurs above the glass transition temperature. Furthermore, the thermal strengths at 180 °C and 220 °C do not differ. Therefore, composition C2 is also not thermomechanically removable within the meaning of the invention.

[0268] The compound of Example V3 has a different epoxy resin composition compared to Example V2. The cured compound of Example V3 also exhibits a further inflection point above the glass transition temperature, as well as a drop in storage modulus of 81% in the temperature range between onset and endset. Therefore, analogous to the compounds of Examples V1 and V2, it is efficiently thermomechanically removable.

[0269] The composition from Example V4 is dual-curing according to the second preferred embodiment. Example V4 additionally contains (meth)acrylate as a radically curable compound (e) and a photoinitiator for radical polymerization (f1). The composition can be fixed by irradiation with actinic radiation and subsequently heat-cured. Due to the use of a semi-crystalline polymeric filler (d), the storage modulus of this composition also exhibits a further inflection point in the DMTA curve above the glass transition temperature of the cured composition. The drop in the storage modulus in the temperature range between onset and endset is 59%. Thus, the composition of Example V4 is also thermomechanically efficiently removable.

[0270] The compositions of inventive examples C5 and C7 and Comparative Example C3 contain a combination of different hardeners for epoxy curing (b). By combining several hardeners, rapid curing at low temperatures can be achieved without the further addition of an accelerator (c). The cured composition from example C5 exhibits a further inflection point above the glass transition temperature in the temperature range between onset and endset and a decrease in storage modulus by 69%. Thus, the composition from example C5 is also efficiently thermomechanically removable. The compositions of inventive examples C6 and C7 contain a semi-crystalline polyamide as polymeric filler (d2), whose melting point is 190 °C. The decrease in storage modulus in the DMTA measurement occurs in a temperature range of 172 - 180 °C, with the further inflection point being at a temperature of 174 °C.Efficient removal of the hardened mass is therefore possible even at temperatures below 190 °C.

[0271] In contrast, the mass from comparative example C3 shows no significant decrease in the storage modulus in the DTMA measurement above the glass transition temperature.

[0272] Figure 1 shows the DMTA curve of the storage modulus of the cured compositions of Examples V5 and V7. The glass transition temperature of the resin matrix is ​​indicated as an inflection point at 117 °C and 124 °C, respectively. The curves each exhibit a further inflection point above the glass transition temperature. This is 199 °C for Example V5 and 174 °C for Example V7. Accordingly, the absolute value of the first derivative of the storage modulus results in a maximum at the glass transition point and a maximum at the further inflection point in the region of modulus drop. The storage modulus of the compositions V5 and V7 drops by 69% and 76%, respectively, in the temperature range between onset and endset.

[0273] The DMTA curve of Comparative Example C3, also shown in Figure 1, shows no further inflection point above the glass transition temperature of the resin matrix of 120 °C. Only a slight decrease in the storage modulus can be observed, which occurs due to temperature-induced softening of the compound. The compound is therefore not resoluble within the meaning of the invention.

Claims

Patent claims 1. Use of a curable mass for producing a component with a thermomechanically removable joint, a coating or a potting compound, wherein the mass comprises the following components: (a) at least one epoxy compound comprising at least one di- or higher-functional aromatic epoxide; (b) at least one hardener suitable for epoxy curing; (c) optionally an accelerator for epoxy curing; (d) at least one polymeric filler in a proportion of 15% by weight or more, based on the total weight of the composition, wherein the polymeric filler is selected from the group of polyamides; (e) optionally one or more compounds curable by radical polymerisation; (f) optionally at least one initiator for radical polymerization; and (g) optionally further additives, wherein the polymeric filler is present in the mass as at least a semi-crystalline solid and the melting point of the polymeric filler is at least 120 °C.

2. Use according to claim 1, characterized in that the proportion of the polymeric filler is at least 20% by weight.

3. Use according to claim 1 or 2, characterized in that the melting point of the filler is in the range of 120 to 300 °C.

4. Use according to one of the preceding claims, characterized in that the filler has a melting enthalpy of at least 40 J / g.

5. Use according to one of the preceding claims, characterized in that the filler has a particle size distribution with an average particle diameter D50 of at most 100 pm.

6. Use according to one of the preceding claims, characterized in that the cured mass has at least one further inflection point in the DMTA curve of the storage modulus above the glass transition temperature.

7. Use according to one of the preceding claims, characterized in that the component is a magnet, a stator and / or a rotor for an electric motor.

8. A curable composition for producing a thermomechanically detachable joint, a coating or a potting compound, the composition comprising the following components: (a) at least one epoxy compound comprising at least one di- or higher-functional aromatic epoxide; (b) at least one nitrogen-based hardener suitable for epoxy curing; (c) optionally an accelerator for epoxy curing; (d) at least one polymeric filler in a proportion of 20% by weight or more, based on the total weight of the composition, wherein the polymeric filler is selected from the group of polyamides; (e) optionally one or more radically radiation-curable compounds; (f) optionally at least one initiator for radical polymerization; and (g) optionally further additives, wherein the polymeric filler is present in the mass as an at least semi-crystalline solid having an enthalpy of fusion of 40 J / g or more, and wherein the melting point of the polymeric filler is at least 120 °C.

9. A method for producing a component using a curable composition according to any one of claims 1 to 8, the method comprising the following steps: Dosing the composition onto a first substrate; optionally feeding a further substrate to form a substrate composite, wherein the further substrate is brought into contact with the composition; optionally irradiating the composition with actinic radiation, wherein the irradiated composition achieves a fixing strength sufficient for further processing of the first substrate or the substrate composite; and Heating the optionally irradiated mass on the substrate or in the substrate composite to a predetermined curing temperature until curing, forming the component with the substrate and a cured adhesive layer bonded to the first substrate and optionally to the further substrate, wherein the adhesive layer is thermomechanically detachable from the substrate by heating to a predetermined detachment temperature.

10. Component obtainable by the preceding method according to claim 9.

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