DE102022120396A1 - Use of a hardenable and resoluble mass for producing a component, and mass therefor - Google Patents

Abstract

The invention relates to a curable mass which is used to produce a component with a thermomechanically removable joint, a coating or a potting, the mass comprising the following components: (a) at least one epoxy compound which contains at least one di- or higher-functional aromatic epoxide includes; (b) at least one hardener suitable for epoxy curing; (c) optionally an epoxy curing accelerator; (d) at least one polymeric filler in a proportion of 15% by weight or more, based on the total weight of the composition, the polymeric filler being selected from the group of polyamides; (e) optionally one or more radical polymerization curable compounds; (f) optionally at least one radical polymerization initiator; and (g) optionally further additives, wherein the polymeric filler is present in the mass as an at least partially crystalline solid and the melting point of the polymeric filler is at least 120 ° C. Furthermore, a method for producing components using the mass and components produced with it are described.

Description

FIELD OF THE INVENTION

The present invention relates to the use of a curable mass for producing a component with a thermomechanically removable joint, a coating or a casting, and a curable mass for producing the component. The curable composition comprises at least an epoxy compound, a hardener for the epoxy compound and a polymeric filler.

In addition, 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 a component obtainable by the method.

TECHNICAL BACKGROUND

The circular economy strives for a system in which the use of resources and the production of waste is minimized, for example by closing energy and material cycles. From this point of view, the recycling of components or components in industry represents a major challenge. Particularly in the case of high-priced or globally limited available parts that experience relatively little aging over a long service life, there is a strong desire to use these directly or in new product generations recycled form. However, the components are often located in complex devices that must first be dismantled in order to separate the components from other components. In the spirit of the circular economy, it is desirable to use as little energy as possible in the dismantling processes and to avoid harsh processes such as pyrolysis. In addition, for ecological reasons, it is advisable to avoid using solvents during dismantling. Accordingly, there is a need in the state of the art for materials that enable the re-detachment of joint connections with an acceptable energy input and under the mildest possible conditions. At the same time, however, these masses must not shorten the service life of the machine during operation or impair its performance.

There are different approaches in the prior art for making joining connections removable. The joining partners are often separated from each other thermomechanically, with heat input through mechanical force. Other options include the use of solvents as well as pyrolysis, exposure or electricity to the joint.

The EP 1 096 517 A2 discloses a recycling process for producing magnetic powder from joined magnets. The joint includes thermoplastic materials and is dissolved by solvents under harsh conditions.

The WO 1998 031 738 A1 describes epoxy-amine compounds with a modified amine hardener, which also contain a plasticizer. The compounds are intended for use in bonding semiconductor elements in connection with repairs. The repair process involves softening the hardened mass by treating it with hot air at 250 °C for one minute.

The JP 3 808 819 B2 describes a process for recycling assembled magnets by treating them with hot water and then peeling the magnets off. The adhesive used to hold the magnets in position also has organic thermally expandable particles that expand when exposed to 70 - 120 °C hot water. Such masses are not suitable for magnets such as those used in powerful electric motors, since the specified release temperature is regularly reached or exceeded during normal operation.

The US 5,872,158 A describes removable materials based on (meth)acrylates that contain acetal-functionalized diacrylates. The disclosure provides for the hardened mass to be dissolved by treatment with dilute acid to split the acetal groups.

The 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% by weight of organic additives is excluded, as this causes the viscosity of the masses to increase unfavorably. To remove a silicon chip from the hardened mass, it is used a mixture of solvents such as N,N-dimethylformamide or bis (2-methoxyethyl) ether. This approach is ecotoxicologically questionable and can also undesirably damage surrounding components.

WO 2021 033 368 A1 discloses epoxy-amine compositions which additionally contain a polymeric component and at least one inorganic filler. The polymeric component comprises at least one phenoxy resin, which is dissolved in the masses. There is no provision for re-detachment of joint connections.

The EP 2 084 205 B1 describes fiber-reinforced composites that contain at least one difunctional and also one trifunctional epoxy resin. Nitrogen-based compounds are suggested as hardeners. In addition, insoluble particles from the polyamide group are added to the masses. These improve the so-called CAI value (compression after impact) and thus the mechanical recovery behavior of the hardened masses. Removability of the masses is not described. Instead, the use of the masses in the aerospace industry as a matrix for the production of prepregs is described.

The materials described in the prior art either require very harsh conditions to be removed again or are not suitable for long-term use as joining material in machines that are already subject to high thermal loads during normal operation.

SUMMARY OF THE INVENTION

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

In particular, masses should be provided that are removable and maintain their high bond strength and durability over the course of the life cycle of the device or component in which they are used, even under thermal stress or stress from media.

These objects are achieved according to the invention by using a curable composition according to claim 1, a curable composition according to claim 8, a method for producing a component using the composition according to claim 9 and a component obtainable by the method according to claim 10.

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

1. (a) mindestens eine Epoxidverbindung, die mindestens ein di- oder höherfunktionelles aromatisches Epoxid umfasst;
2. (b) mindestens einen Härter, der für die Epoxidhärtung geeignet ist, bevorzugt einen Härter auf Stickstoffbasis;
3. (c) wahlweise einen Beschleuniger für die Epoxidhärtung;
4. (d) mindestens einen polymeren Füllstoff in einem Anteil von 15 Gew.-% oder mehr, bezogen auf das Gesamtgewicht der Masse, wobei der polymere Füllstoff aus der Gruppe der Polyamide ausgewählt ist;
5. (e) wahlweise eine oder mehrere durch radikalische Polymerisation härtbare Verbindungen;
6. (f) wahlweise mindestens einen Initiator für die radikalische Polymerisation; und
7. (g) wahlweise weitere Zusatzstoffe,

According to the invention, to produce a component with a thermomechanically removable joint, a coating or a casting, a hardenable mass is used which comprises the following components:

1. (a) at least one epoxy compound comprising at least one di- or higher-functional aromatic epoxide;
2. (b) at least one hardener suitable for epoxy curing, preferably a nitrogen-based hardener;
3. (c) optionally an epoxy curing accelerator;
4. (d) at least one polymeric filler in a proportion of 15% by weight or more, based on the total weight of the composition, the polymeric filler being selected from the group of polyamides;
5. (e) optionally one or more radical polymerization curable compounds;
6. (f) optionally at least one radical polymerization initiator; and
7. (g) optionally further additives,

The polymeric filler is present in the mass as an at least partially crystalline solid, the melting point of the polymeric filler being at least 120 ° C.

The component preferably has a joint connection. The compositions according to the invention are particularly suitable for bonding magnets, preferably for producing stators and/or rotors for electric motors.

1. (a) mindestens eine Epoxidverbindung, die mindestens ein di- oder höherfunktionelles aromatisches Epoxid umfasst;
2. (b) mindestens einen Härter auf Stickstoffbasis, der für die Epoxidhärtung geeignet ist;
3. (c) wahlweise einen Beschleuniger für die Epoxidhärtung;
4. (d) mindestens einen polymeren Füllstoff in einem Anteil von 20 Gew.-% oder mehr, bezogen auf das Gesamtgewicht der Masse, wobei der polymere Füllstoff aus der Gruppe der Polyamide ausgewählt ist;
5. (e) wahlweise eine oder mehrere radikalisch strahlungshärtbare Verbindungen;
6. (f) wahlweise mindestens einen Initiator für die radikalische Polymerisation; und
7. (g) wahlweise weitere Zusatzstoffe,

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

1. (a) at least one epoxy compound comprising at least one di- or higher-functional aromatic epoxide;
2. (b) at least one nitrogen-based hardener suitable for epoxy curing;
3. (c) optionally an epoxy curing accelerator;
4. (d) at least one polymeric filler in a proportion of 20% by weight or more, based on the total weight of the mass, the polymeric filler being selected from the group of polyamides;
5. (e) optionally one or more radical radiation curable compounds;
6. (f) optionally at least one radical polymerization initiator; and
7. (g) optionally further additives,

In this embodiment, the polymeric filler, which is present in the mass as an at least partially crystalline solid, has an enthalpy of fusion 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 mass according to the invention is characterized by re-removability at a predetermined temperature, at which a significant drop in modulus and thus a high loss of strength can be observed in the DMTA curve of the storage modulus of the hardened mass. At the same time, the hardened masses have a high degree of crosslinking and a high glass transition temperature. This ensures a low loss of strength under thermal stress and good media resistance.

1. a) Dosieren der Masse auf ein erstes Substrat;
2. b) Wahlweise Zuführen eines zweiten Substrats unter Bildung eines Substratverbundes, wobei das zweite Substrat mit der Masse in Kontakt gebracht wird;
3. c) Wahlweise Bestrahlen der Masse mit aktinischer Strahlung, wobei die bestrahlte Masse eine Fixierfestigkeit erreicht, welche für eine Weiterverarbeitung des ersten Substrats oder des Substratverbundes ausreichend ist; und
4. d) Erwärmen der wahlweise bestrahlten Masse auf dem Substrat oder in dem Substratverbund auf eine vorbestimmte Aushärtetemperatur bis zur Aushärtung, unter Bildung des Bauteils mit dem Substrat und einer ausgehärteten, mit dem Substrat und wahlweise dem weiteren Substrat verbundenen Klebeschicht, wobei die ausgehärtete Klebeschicht durch Erwärmen auf mindestens eine Ablösetemperatur thermomechanisch von dem Substrat lösbar ist.

According to a further aspect, the invention relates to a method for producing a component using the curable mass as described above, the method comprising the following steps:

1. a) metering the mass onto a first substrate;
2. b) Optionally supplying a second substrate to form a substrate composite, the second substrate being brought into contact with the mass;
3. c) Optionally irradiating the mass with actinic radiation, the irradiated mass achieving a fixing strength which is sufficient for further processing of the first substrate or the substrate composite; and
4. 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 connected to the substrate and optionally the further substrate, the cured adhesive layer being heated can be thermomechanically detached from the substrate to at least one release temperature.

The component preferably comprises a substrate composite with at least two substrates connected by the adhesive layer.

The storage modulus (E') of the hardened mass, measured as a function of the temperature by dynamic-mechanical-thermal analysis (DMTA), has at least one further turning point above the glass transition temperature in the curve.

The further turning point lies within a temperature range in which a steep and pronounced drop in the storage modulus and the strength of the hardened mass can be observed. The difference between end set and onset of the temperature range encompassing the further turning point, i.e. between end set and onset of the module drop, is preferably at most 30 ° C, more preferably at most 20 ° C or at most 15 ° C. The drop in modulus in the DMTA curve particularly preferably occurs over a temperature interval of 10 ° C or less. The absolute temperature of the further turning point in the DMTA curve can be influenced by the selection of the semi-crystalline polymer filler.

The release temperature at which the adhesive layer can be thermomechanically detached from the substrate or substrate composite is preferably chosen so that it is at or above the further turning point the DMTA curve of the storage modulus of the hardened mass. More preferably, the detachment temperature is in a range between the temperature at the further turning point and up to 50 ° C, more preferably up to 20 ° C, above the end set of the module waste. It will be clear to those skilled in the art that the adhesive layer can also be removed again at higher temperatures. The closer the removal temperature is to the end set of the module waste, the more energy efficient the valuable substrates can be recovered.

In preferred embodiments, the release 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 that the components to be recovered could be thermally damaged. Furthermore, such high temperatures hardly offer any energetic advantages over pyrolysis.

The invention furthermore relates to a component with a removable adhesive layer, which is obtainable by the method described above.

DESCRIPTION OF THE DRAWING

• - 1 eine DMTA-Kurve mit einer Darstellung des Speichermoduls in Abhängigkeit der Temperatur für eine Referenzmasse und zwei erfindungsgemäß verwendete Massen.

In the drawing shows:

• - 1 a DMTA curve with a representation of the storage modulus as a function of the temperature for a reference mass and two masses used according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention is described below in detail and by way of example using preferred embodiments, which, however, should not be understood in a restrictive sense.

For the purposes 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.

If the indefinite article “a” or “an” is used, the plural form “one or more” is also included, unless this is expressly excluded.

“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.

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

The compositions according to the invention can be formulated as either one or more components.

Component (a): Epoxy compound

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

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

Aromatic glycidyl ethers are available 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 (D.E.R. 331, Epikote Resin 828), bisphenol F epoxy resins (Epikote Resin 862, Epikote Resin 863, YDF-170), mixtures of bisphenol A and F diglycidyl ethers (D.E.R. 351, Epikote Resin 166, YDF-161), phenol novolak epoxy resins (D.E.N. 424, D.E.N. 437, D.E.N. 440, YDPN-631) and cresol novolak epoxy resins (DIC Corporation Epiclon N-670, YDCN-500- 5P).

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, for example based on p-tert -Butylphenol (DER 727) or cardanol (Cardolite Lite 513) can be used.

In addition, 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), dicyclopentadienedimethanol ( Adeka EP 4088S). It is also possible to use reaction products from epichlorohydrin and amines or aminophenols such as TGAP (triglycidyl ether of aminophenol; Araldite MY 0610) or TGMDA (tetraglycidyl ether of methylenedianiline, Araldite MY 721).

Furthermore, all fully or partially hydrogenated analogues of aromatic epoxy compounds can also 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 therephthalic acid (ARALDITEO PT 910, Huntsman), cycloaliphatic compounds or aliphatic compounds (Cardura E10, Westlake) can also be used.

In addition to the epoxy compounds mentioned so far, 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-methaneindane, and mixtures thereof.

Epoxidized compounds based on fats/oils such as Sovermol 1055, BASF can also be used.

Isocyanurates and other heterocyclic compounds substituted with epoxide-containing groups can also be used as component (a) in the compositions according to the invention. Triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate are mentioned as examples.

In addition, mono- and polyfunctional epoxy resins from all of the resin groups mentioned can also be used, which contain other functional groups in addition to the epoxy functionalities. Examples of this are OH-functional, oligomeric aromatic epoxy compounds (e.g. Dow D.E.R. 671 or Kukdo KD-9004).

Addition products of the epoxy compounds mentioned with H-acidic compounds (in low molecular weight or in polymeric form) such as carboxylic acids, alcohols and/or thiols can also be used. Particularly preferred examples of this 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).

Also within the scope of the invention is a combination of several epoxide-containing compounds, at least one of which is di- or higher-functional.

Furthermore, in addition to all of the epoxide-containing compounds mentioned, sulfur analogues can also be used as component (a). The corresponding thiiranes are therefore also within the meaning of the invention. Epoxides in which only some of the epoxy groups have been replaced by thiiranes can also be used advantageously.

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% by weight, more preferably 20 to 70% by weight.

Monofunctional epoxy compounds can be contained in component (a) in a proportion of up to 30%, based on the weight of component (a).

Component (b): Hardener for the epoxy compound

The compositions according to the invention contain at least one hardener (b) for epoxy hardening. The chemical structure of component (b) is not further restricted 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 compounds mentioned . The hardener is preferably present in the masses in solid form.

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 . The hardeners mentioned each preferably comprise at least two nitrogen-containing groups per molecule that are suitable for epoxy hardening.

Commercial examples of suitable hardeners from the cyanamide group are Dyhard100 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).

Commercial examples of suitable hydrazides include Technicure ADH-J (ACCI Specialty Materials), Technicure IDH-J (ACCI Specialty Materials), Ajicure UDH-J (Ajinomoto) and Ajicure VDH-J (Ajinomoto).

By combining different hardeners (b), the epoxy hardening can be accelerated without adding component (c). Commercial examples of nitrogen-containing compounds that have an accelerating effect on curing, particularly 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

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

The above lists are to be seen as examples and not exhaustive. Mixtures of the hardeners (b) mentioned are also within the meaning of the invention.

Anhydrides and thiols can also be used as hardeners (b) for epoxy hardening.

Specific examples of anhydrides that can be used as curing agents for epoxides in the present compositions include the anhydrides of diprotic acids, such as phthalic anhydride (PSA), succinic anhydride, octenyl succinic anhydride (OSA), pentadodecenyl succinic anhydride and other alkenyl succinic 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), tetrabromphthalic anhydride and trimellitic anhydride, as well as the Anhydrides of aromatic tetraprotic acids, such as for example, biphenyltetracarboxylic dianhydrides, naphthalenetetracarboxylic dianhydrides, diphenylethertetracarboxylic dianhydrides, butanetetracarboxylic dianhydrides, cyclopentanetetracarboxylic dianhydrides, pyromellitic anhydrides and benzophenonetetracarboxylic dianhydrides. These compounds can be used alone or in combinations of two or more of them.

Among these anhydrides, compounds that are liquid at room temperature are preferred, such as methylhexahydrophthalic anhydride (MHHPA), methyltetrahydrophthalic anhydride (MTH PA), and methylenedome ethylenetetrahydrophthalic anhydride (METH, NMA) and its hydrogenation product are used as hardeners (b).

The preferred anhydrides for use as hardeners (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 S.p.A.), and MHAC (Hitachi Chemical Co., Ltd.).

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 and combinations thereof.

The at least difunctional thiol is preferably selected from the group consisting of ester-based thiols, polyethers with reactive thiol groups, polythioethers, polythioether acetals, polythioetherthioacetals, 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, pentaerythritol tetramercaptoacetate and glycol dimercaptoacetate, which are available under the brand names Thiocure™ TMPMA, PETMA and GDMA from Bruno Bock.

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 listed below The brand names Thiocure TMPMP, PETMP, GDMP and TEMPIC are available from the company Bruno Bock.

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

With regard to increased resistance of the cured masses to temperature and humidity, the use of ester-free thiols is particularly preferred. Examples of ester-free thiols can be: JP 2012 153 794 A be removed.

Particular preference is given to using tris(3-mercaptopropyl)isocyanurate (TMPI) as a trifunctional ester-free thiol.

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

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

The above list is to be seen as an example and not exhaustive.

The proportion of hardener (b) in the composition according to the invention is preferably 1 to 50% by weight, more preferably 2 to 30% by weight.

Component (c): accelerator

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

Examples of suitable accelerators based on ureas and their derivatives are urones. Commercial examples include Dyhard UR 500 (Alzchem), Dyhard UR 300 (Alzchem), EPICURE Catalyst 116 (Westlake), Technicure MDU-11M (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), EPICURE Catalyst 116 (Westlake).

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

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

The accelerators (c) listed here are explicitly to be understood as additionally accelerating compounds which are not included in component (b) and its combinations. The use of multiple accelerators is also within the scope of the invention.

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.

Component (d): polymeric filler

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 polymeric filler is present in the mass as an at least partially crystalline solid in a proportion of 15% by weight or more, based on the total weight of the mass. A lower proportion of the semi-crystalline polymeric filler leads to masses with insufficient re-removability of the hardened mass at the predetermined release temperature. Adhesive layers made from these materials can only be removed from the respective substrates with greater effort.

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

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 the hardened mass containing the filler at a heating rate of 10 K/min.

More preferably, the average particle size D50 of the polymeric filler (d), which can be determined by laser light diffraction, is less than 100 μm, more preferably less than 50 μm.

Commercially available examples of the polymeric filler include Rilsan types 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 into the appropriate particle size distribution by, for example, mechanical grinding.

Component (d) is selected in the context of the intended application of the hardened mass. The melting point of the filler (d) is preferably chosen so that it is at least 5 ° C, preferably at least 10 ° C, above the average temperature to which the hardened mass is permanently exposed during use. In the interests of energy-efficient replacement, a small temperature difference between the onset of the module drop in the DMTA curve of the storage module and the application temperature of the mass below it is preferred. If these are applications in which temperature peaks can occur more frequently, a higher temperature difference is preferred for reasons of reliability.

The polymer filler (d), which is used in the compositions according to the invention, has an enthalpy of fusion of at least 40 J/g, preferably 50 J/g. The enthalpy of fusion indicates the degree of crystallization of the filler (d) used.

The proportion of the at least partially crystalline polymeric filler (d) in the composition according to the invention is at least 15% by weight, preferably at least 20% by weight or 25% by weight, but at most 50% by weight, in each case based on the total weight of the Dimensions. A higher proportion of the at least partially crystalline polymeric filler can result in the liquid curable masses having a high viscosity that is unfavorable for processing, and the hardened masses having insufficient temperature resistance or media resistance.

Component (e): radically curable compound

The compositions optionally contain a compound (e) which can be curable by radical polymerization and which comprises at least one (meth)acrylate. The term “(meth)acrylate” in the sense of the invention includes both acrylates and the analogous methacrylates. The use of component (e) allows the mass to be fixed quickly, in particular by irradiation with actinic radiation.

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

(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.

(Meth)acrylates are preferred 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.

The compositions preferably contain at least one di- or higher-functionality (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, tricyclodecanedimethanol 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.

The (meth)acrylates mentioned are commercially available, for example, from the companies Arkema Sartomer, BASF, IGM Resins, Sigma Aldrich or TCl.

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

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-1 H-indenylmethyl (meth)acrylate.

(Meth)acrylates with a low dissolving power in relation to the hardener (b) are preferred. This enables an advantageous latency of the masses at room temperature.

Furthermore, hybrid compounds can also be used which, in addition to a radiation-curable group, also contain an addition-crosslinkable group. Examples that have 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.

The above list of suitable substance classes is intended as an example and not in a restrictive sense.

Component (e) is present in the compositions according to the invention in a proportion of 0 to 40% by weight, preferably 1 to 30% by weight, based in each case on the total weight of the composition.

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

Component (f): Initiator for the radical polymerization

To harden component (e), the compositions according to the invention optionally comprise at least one initiator (f) for the radical polymerization. Photoinitiators (f1), in combination with component (e), enable the mass to be fixed by irradiation with actinic radiation. Thermal initiators for the 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 areas of the curable mass that cannot be reached with actinic radiation.

The usual, commercially available compounds can be used as radical photoinitiators (f1), such as α-hydroxyketones, benzophenone, α,α'-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-benzoyl benzoate, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-isopropylthioxanthone, 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.

The radical photoinitiator (f1) can preferably be activated by irradiation with actinic radiation with a wavelength of 200 to 600 nm, particularly preferably 320 to 480 nm. If necessary, the radical photoinitiator can be combined with a suitable sensitizing agent.

The IRGACURE ™ types of BASF SE, for example, can be used as commercially available photinitiators, such as the types Irgacure 184, Irgacure 500, Irgacure 2959, Irgacure 745, Irgacure 369, Irgacure 1300, Irgacure 819 , IRGACURE 819DW, IRGACURE 2022, IRGACURE 2100, IRGACURE 784, IRGACURE 250, IRGACURE TPO, IRGACURE TPO-L. The DAROCUR™ grades from BASF SE can also be used, such as the grades DAROCUR MBF, DAROCUR 1173, DAROCUR TPO and DAROCUR 4265.

The above list of suitable substance classes is intended as an example and not in a restrictive sense.

Combinations of several photoinitiators are also according to the invention.

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

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 benzopinacol.

Examples of suitable peroxoesters include cumene peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxypivalate, tert-amyl peroxypivalate, tert -Butyl peroxypivalate, didecanoyl peroxide, dilauroyl peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)-hexane, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, tert- Amyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxyacetate and tert-butyl peroxybenzoate.

Examples of suitable hydroperoxides include di-isopropylbenzene monohydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide, 1,1,3,3-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-butyl-peroxyisopropyl)-benzene, 2,5-dimethyl -2,5-di-(tert-butylperoxy)-hexane, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexine and di-tert-butyl peroxide.

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

Examples of suitable peroxymonocarbonates include tert-amyl peroxy-2-ethylhexyl carbonate, tert-butyl peroxyisopropyl carbonate and tert-butyl peroxy-2-ethylhexyl carbonate.

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

The thermal initiator (f2) can be included in addition to or instead of the radical photoinitiator (f1).

Component (g): Additives

In addition to components (a) to (f), the compositions according to the invention can contain further additives (g). Preferred additives (g) are toughness modifiers such as core-shell particles (Kaneka KaneAce™ series, Dow Paraloid™ EXL series, Wacker ^Genioperl® ) or block copolymers, reactive elasticizers (for example 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.

In addition to the polymeric filler (d), in particular other organic or inorganic fillers that are not covered by component (d) can be included as additive (g1). These allow, for example, the adjustment of the mechanical, enthalpic, thermal, rheological and electrical properties of the masses and can be used advantageously to increase the resistance of the hardened mass to temperature, moisture and media influences.

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 metalloids, all types of glasses, metals and metalloids in elemental form, in the form of alloys or intermetallic phases and particles of polymeric materials such as silicone and PTFE.

In order to accelerate the heat input to redissolve the masses, especially when irradiated with IR emitters, IR-absorbing dyes, such as those in the EP 3 943 534 A1 are described, can be used advantageously as additive (g2). These not only allow thermal energy to be introduced more efficiently into the adhesive layer, but also allow the hardened mass to be heated up more quickly and thus removed again.

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

Formulation of the compositions according to the invention:

• a) Mindestens einer Epoxidverbindung, die mindestens eine di- oder höherfunktionelle aromatische Epoxidverbindung umfasst;
• b) Mindestens einem fester Härter auf Stickstoffbasis, ausgewählt aus der Gruppe der Amine, Hydrazide, Cyanamide oder Imidazole;
• c) wahlweise einem Beschleuniger für die Epoxidhärtung;
• d) 15 - 50 Gew.-% eines organischen Füllstoffes, ausgewählt aus der Gruppe der Polyamide;
• g) wahlweise weiteren Zusatzstoffen.

According to a preferred embodiment, the mass 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 other additives.

1. a) Mindestens einer Epoxidverbindung, die mindestens eine di- oder höherfunktionelle aromatische Epoxidverbindung umfasst;
2. b) Mindestens einem festen Härter auf Stickstoffbasis, ausgewählt aus der Gruppe der Amine, Hydrazide, Cyanamide oder Imidazole;
3. c) wahlweise einem Beschleuniger für die Epoxidhärtung;
4. d) 15 - 50 Gew.-% eines organischen Füllstoffes, ausgewählt aus der Gruppe der Polyamide,
5. e) 1 - 30 Gew.-% einer durch radikalische Polymerisation härtbaren Verbindung, die mindestens ein (Meth)Acrylat umfasst;
6. f) mindestens eines Initiators für die radikalische Polymerisation, ausgewählt aus der Gruppe der Photoinitiatoren und/oder thermischen Initiatoren, und;
7. g) wahlweise weiteren Zusatzstoffen.

According to a second preferred embodiment, the mass according to the invention consists of the following components, each based on the total weight of components a) to g):

1. a) at least one epoxy compound comprising at least one di- or higher-functional aromatic epoxy compound;
2. b) at least one solid nitrogen-based hardener selected from the group of amines, hydrazides, cyanamides or imidazoles;
3. c) optionally an accelerator for epoxy curing;
4. d) 15 - 50% by weight of an organic filler, selected from the group of polyamides,
5. e) 1-30% by weight of a compound curable by radical polymerization and comprising at least one (meth)acrylate;
6. f) at least one initiator for the radical polymerization, selected from the group of photoinitiators and/or thermal initiators, and;
7. g) optionally other additives.

The compositions of the second embodiment can also be fixed by irradiation if they contain at least one photoinitiator for the radical polymerization. They are therefore suitable for converting the liquid mass into a dimensionally stable state before heat curing, in which no more flow can occur. This makes handling the mass easier in further process steps. Instead of or in addition to the use of a photoinitiator, thermal initiators can also be used as component (f). This means that radically curable components in shadow zones can also be completely hardened by heating.

Hardening of the compositions according to the invention

At temperatures of 100 to 160 °C, the masses can be completely hardened within 4 hours, preferably within 2 hours.

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

Heating the mass for hardening can be done, for example, in convection ovens, using thermodes, IR emitters, lasers, microwaves or induction.

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

The curing temperature of the compositions according to the invention is preferably chosen so that it is below the melting point of component (d). As a result, melting of the partially crystalline polymeric filler (d) can be avoided during curing.

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

Use of the compositions according to the invention

The compositions according to the invention are suitable for producing releasable bonds, coatings and castings. In particular, the masses are suitable for components that are exposed to high mechanical and thermal loads, both permanently and periodically, in the course of their normal operation. The hardened masses are characterized by the fact that they have high strength and durability, but at the same time are resoluble at elevated temperatures. Components that were joined using the compound can be heated to a predefined temperature with only a small amount Force input can be released again. The release temperature is preferably at or above the further turning point in the DMTA curve of the storage modulus of the hardened mass.

For example, the masses can be used to produce electric motors (e-motors). In particular, magnets in electric motors can be glued using the masses. Particularly in powerful electric motors, the magnets contain rare earth metals, the recovery of which is often of great economic interest. At the same time, over the lifespan of an electric motor, the masses are exposed to high temperatures and, depending on the application, sometimes to stress from media such as dust, oils, grease, coolants, lubricants or solvents. The masses of the present invention can withstand these loads even over a long period of operation.

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

In principle, the masses are always suitable for applications in which very expensive components are used, the disposal of which represents a major economic loss.

If the hardened mass is to be detached from a component or from a substrate composite, detachment temperatures are advantageously selected which are at or above the temperature at the further turning point in the DMTA curve of the storage modulus of the hardened mass.

The detachment temperature is preferably in a range between the temperature at the further turning point and up to 50 ° C, more preferably up to 20 ° C, above the end set of the module waste. In preferred embodiments, the release 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 that the components to be separated could be thermally damaged.

The heat required to reach the release temperature can be introduced, for example, via an oven, induction, laser, microwaves, thermodes or infrared radiators.

The duration of the heat input varies depending on the method of heat generation, the size and nature of the components, the amount of mass to be removed and the accessibility of the adhesive layer to heat.

Particularly for large components made of metallic materials, heat can be introduced quickly and efficiently using alternating inductive fields.

Above the temperature at the further turning point in the DMTA curve of the storage module, the joint connections from the hardened mass can be released using small mechanical forces and the components can be separated from one another. A low residual strength of the hardened mass, even when heated to temperatures above the release temperature, ensures that large components in particular do not separate from one another in an uncontrolled manner.

So that the necessary force input into the components can remain low, it would be advantageous to have the lowest possible storage modulus of the hardened masses. However, this contradicts the requirements for a firm and permanent bond, even under high thermal and mechanical loads. In order to be able to meet both requirements, the hardened masses in the DMTA curve preferably have a drop in the storage modulus between onset and endset of the temperature range encompassing the further turning point, above the glass transition temperature, of at least 30%, more preferably at least 45%.

A smaller drop in the storage modulus can also occur due to a temperature-related softening of the hardened mass. However, this drop is essentially continuous over a wide temperature range and does not represent a turning point in the sense of the invention. Efficient thermomechanical re-removability is only possible to a sufficient extent when using the polymeric filler (d).

Below the temperature at the further turning point, the joints produced using the compounds according to the invention show high strength, in particular tensile shear strength, and high resistance to mechanical, thermal and chemical loads. First with If the temperature at the further turning point is exceeded and/or the release temperature is reached, an almost sudden drop in strength occurs.

Joining or coating processes using the compositions according to the invention

1. a) Dosieren der Masse auf ein erstes Substrat;
2. b) Wahlweise Zuführen eines zweiten Substrats unter Bildung eines Substratverbundes, wobei das zweite Substrat mit der Masse in Kontakt gebracht wird;
3. c) Wahlweise Bestrahlen der Masse mit aktinischer Strahlung zum Erreichen einer Fixierfestigkeit, welche für eine Weiterverarbeitung des ersten Substrats oder des Substratverbundes ausreichend ist; und
4. d) Erwärmen der wahlweise bestrahlten Masse auf dem Substrat oder in dem Substratverbund auf eine vorbestimmte Aushärtungstemperatur bis zur Aushärtung, unter Bildung des Bauteils mit dem Substrat und einer ausgehärteten, mit dem Substrat und wahlweise dem weiteren Substrat verbundenen Klebeschicht, wobei die Klebeschicht durch Erwärmen auf eine vorbestimmte Ablösetemperatur thermomechanisch von dem Substrat lösbar ist.

A method for producing a component using a curable mass according to the invention preferably comprises the following steps:

1. a) metering the mass onto a first substrate;
2. b) Optionally supplying a second substrate to form a substrate composite, the second substrate being brought into contact with the mass;
3. c) Optionally irradiating the mass with actinic radiation to achieve a fixing strength which is sufficient for further processing of the first substrate or the substrate composite; and
4. 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 connected to the substrate and optionally the further substrate, the adhesive layer being formed by heating a predetermined release temperature can be thermomechanically detached from the substrate.

In order to ensure sufficient metering capability, the masses are preferably liquid at room temperature and typically have a viscosity between 10 and 700 Pa*s.

If the application requires it, the first or second substrate can optionally be aligned relative to the other after joining in step b) before fixing by irradiating the mass.

In a further preferred embodiment, the mass is used in a so-called B-stage process. In this case, the mass can be metered onto the first substrate and the supply of a second substrate separated in time and space by fixing the mass with actinic radiation after application to the first substrate. The flowability is limited by the fixing step to such an extent that there is no further change in the dosing pattern on the component. In a subsequent step, the substrate can be joined to another and then completely hardened by heating.

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

Properties of the hardened masses

In addition to being removable from joined, coated or cast substrates, the cured masses based on aromatic epoxy compounds have a high resistance to media, temperature and moisture. At the same time, they have high bond strength even under high temperatures.

The hardened 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 occurring in the application.

The modulus of elasticity of the hardened masses is preferably greater than 100 MPa, preferably greater than 150 MPa.

The glass transition temperature of the hardened 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.

According to the invention, the hardened masses can be removed again at a predetermined release temperature, preferably at or above the temperature at the further turning point in the DMTA curve of the storage module. At this release temperature, the lap shear strength of the hardened masses on steel is preferably at most 2 MPa, more preferably at most 1 MPa.

The at least partially crystalline polyamides used as filler (d) have a relatively narrow melting range. As a result, the drop in strength of the hardened mass also occurs in a narrowly limited temperature interval as soon as the onset of the modulus drop in the DMTA curve of the storage module is exceeded. The release temperature of the mass can therefore be reliably adjusted by selecting the filler (d) and adapted to the respective application.

The storage modulus of the hardened mass, which is measured as a function of the temperature, has at least one further turning point above the glass transition temperature in the dynamic-mechanical-thermal analysis (DMTA) curve. This turning point lies within a temperature range in which a steep and pronounced drop in the storage modulus and the strength of the hardened mass occurs.

In addition to the stage occurring at the glass transition temperature, the addition of the at least partially crystalline polyamide thus creates a further stage in the storage modulus of the hardened mass. When heating above the temperature at the further turning point, this level is exceeded and there is a significant decrease in the storage modulus of the masses used according to the invention. In particular, the drop in the storage modulus between onset and endset of the temperature range encompassing the further turning point is at least 30%, more preferably at least 45%.

In a comparable temperature range, the tensile shear strength of a steel-steel bond with the compounds used according to the invention is also reduced, so that above the temperature at the further turning point, a significantly lower amount of force is required to remove the adhesive layer. At the same time, the glass transition temperatures of the hardened masses and the tensile shear strengths at room temperature are not negatively influenced by the at least partially crystalline polyamide as filler (d).

Measurement methods and definitions used

Radiation

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

Curing

“Crosslinking” or “curing” are defined as a polymerization or addition reaction beyond the gel point. The gel point is the point at which the storage modulus G' becomes equal to the loss modulus G'' during oscillating rheology measurement. The masses were cured in a circulating air oven for 40 minutes at 150 °C.

Room temperature

Room temperature is defined as 23 ± 2 °C.

Assessment of light fixation

To assess light fixation (solid vs. liquid), the masses are subjected to an optical assessment. Optionally, a haptic test can be carried out using a plastic spatula.

Viscosity determination

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

Determination of the melting point and enthalpy of fusion

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

Tensile shear strength at room temperature (aluminum test specimen)

The tensile shear strength at room temperature was determined based on DIN EN ISO 1465:2009-07. Test specimens measuring 100 mm in length, 25 mm in width and 1.6 mm in thickness were used and 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 carried out at room temperature on a universal testing machine “AllroundLine 20kN” from Zwick Roell. The curing time was 40 minutes at 150 °C plus heating time. Aluminum-plated and corundum-blasted specimens made of AIMgCu were used as test specimens.

Tensile shear strength at elevated temperatures (steel test specimen)

The tensile shear strength at elevated temperatures (temperature strength) was determined based on DIN EN 14869-2:2004-10. The length of the test specimens, which deviated from the standard, was 50 mm instead of 57.5 mm for the long side and 30 mm instead of 51 mm for the short side. The thickness of the test specimens was 15 mm instead of 12 mm. The overlap length of the bond 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 45 minutes of heating time. The test specimens were made of corundum blasted steel (S235).

Determination of the glass transition temperature (T _G ) and the storage modulus

The dynamic mechanical properties of the hardened masses were determined by dynamic mechanical thermal analysis (DMTA) based on ISO 6721. The test specimens measuring 40x5x0.5 mm ³ were hardened for 40 minutes at 150 ° C in a suitable plastic mold. The glass transition temperature is defined as the value at which the value of the first derivative of the storage modulus (E') becomes a maximum (turning point, cf. 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 µm. A “DMA 242E” from Netzsch was used as a measuring device.

Particle size distribution

The particle size distribution was determined using a particle size analyzer S3500 from Microtrac by laser light diffraction based on ISO 13320. The distribution given with the size D50 refers to the mean volumetric particle diameter.

Production of the curable masses

To produce the curable masses used in the following examples, the liquid components are first mixed and then the fillers and optionally other solids are incorporated using a laboratory stirrer, laboratory dissolver or a speed mixer (Hauschild) until a homogeneous mass is created. Compounds that contain photoinitiators and that are sensitive to visible light must accordingly be produced under light outside the excitation wavelength of the photoinitiators or sensitizers.

• Komponente (a): Epoxidverbindung
  • (a1) Epikote Resin 169 (Mischung aus Bisphenol A- und Bisphenol F-Diglycidylethern; erhältlich von der Firma Westlake);
  • (a2) Kane ACE MX 257 (in Bisphenol A-Diglycidylether dispergierte Kautschukpartikel; erhältlich von der Firma Kaneka)
  • (a3) Tactix 742 (Triglycidylether von Tris(hydroxyphenyl)methan; erhältlich von der Firma Huntsman)
  • (a4) Epilox P 13-21 (1,4-Butandioldiglycidylether; erhältlich von der Firma Leuna Harze)
  • (a5) Epikote Resin 828 LVEL (chlorarmes Bisphenol A Harz; erhältlich von der Firma Westlake);
• Komponente (b): Härter auf Stickstoffbasis
  • (b1) Epikure Curing Agent 921 Super SH (Dicyandiamid; erhältlich von der Firma Westlake)
  • (b2) Ancamine 2014 FG (Amin-basierter Feststoffhärter; erhältlich von der Firma Evonik)
  • (b3) Technicure IDH-J (Isophthalsäuredihydrazid; erhältlich von der Firma ACCI Specialty Materials)
  • (b4) Adeka Hardener EH-5011S (Imidazol-basierter Feststoffhärter; erhältlich von der Firma Adeka)
• Komponente c): Beschleuniger
  • (c1): DYHARD UR 500 (Uron-basierter Beschleuniger, erhältlich von der Firma Alzchem)
• Komponente (d): Füllstoffe
  • (d1): Orgasol 1002 D NAT 1 (Polyamid 6; erhältlich von der Firma Arkema), Schmelzbereich DSC (10 K/min) 205 °C (Onset) über 214 °C (Peak) bis 220 °C (Endset) mit einem Betrag der Enthalpie von 116 J/g
  • (d2): Rilsan PA11 D30 NAT (Polyamid 11; erhältlich von der Firma Arkema) Schmelzbereich DSC (10 K/min) 180 °C (Onset) über 190 °C (Peak) bis 194 °C (Endset) mit einem Betrag der Enthalpie von 85 J/g
• Komponente (e): radikalisch härtbare Verbindung
  • (e1): Photomer4006 (Trimethylolpropantriacrylat; erhältlich von der Firma IGM Resins)
• Komponente (f): Initiator für die radikalische Polymerisation
  • (f1): Genocure TPO-L (Photoinitiator erhältlich von der Firma Rahn AG) Komponente (g): Weitere Additive
  • (g1): Cab-O-Sil TS-720 (Rheologieadditiv; erhältlich von der Firma Cabot Corporation)
  • (g2): Ulmer Weiß XMF (mikronisierter Kreide-Füllstoff; erhältlich von der Firma Eduard Merkle GmbH & CO. KG)
  • (g3): Elvacite 2614 (mikronisiertes Methacrylat-Copolymer; erhältlich von der Firma Mitsubishi Chemical Corporation)
  • (g4): Dynasylan GLYMO (Haftvermittler; erhältlich von der Firma Evonik)

The following list contains all the compounds used to produce the curable materials and their abbreviations:

• Component (a): Epoxy compound
  • (a1) Epikote Resin 169 (mixture of bisphenol A and bisphenol F diglycidyl ethers; available from Westlake);
  • (a2) Kane ACE MX 257 (rubber particles dispersed in bisphenol A diglycidyl ether; available from Kaneka)
  • (a3) Tactix 742 (triglycidyl ether of tris(hydroxyphenyl)methane; available from Huntsman)
  • (a4) Epilox P 13-21 (1,4-butanediol diglycidyl ether; available from Leuna Harze)
  • (a5) Epikote Resin 828 LVEL (low-chlorine bisphenol A resin; available from Westlake);
• Component (b): Nitrogen-based hardener
  • (b1) Epicure Curing Agent 921 Super SH (dicyandiamide; available from Westlake)
  • (b2) Ancamine 2014 FG (amine-based solid hardener; available from Evonik)
  • (b3) Technicure IDH-J (isophthalic dihydrazide; available from ACCI Specialty Materials)
  • (b4) Adeka Hardener EH-5011S (imidazole-based solid hardener; available from Adeka)
• Component c): Accelerator
  • (c1): DYHARD UR 500 (Uron-based accelerator, available from Alzchem)
• Component (d): Fillers
  • (d1): Orgasol 1002 D NAT 1 (polyamide 6; available from Arkema), melting range DSC (10 K/min) 205 °C (onset) to 214 °C (peak) to 220 °C (end set) with a Enthalpy amount of 116 J/g
  • (d2): Rilsan PA11 D30 NAT (polyamide 11; available from Arkema) Melting range DSC (10 K/min) 180 °C (onset) to 190 °C (peak) to 194 °C (end set) with an amount of Enthalpy of 85 J/g
• Component (e): radically curable compound
  • (e1): Photomer4006 (trimethylolpropane triacrylate; available from IGM Resins)
• Component (f): Initiator for the radical polymerization
  • (f1): Genocure TPO-L (photoinitiator available from Rahn AG) Component (g): Other additives
  • (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)
  • (g3): Elvacite 2614 (micronized methacrylate copolymer; available from Mitsubishi Chemical Corporation)
  • (g4): Dynasylan GLYMO (adhesion promoter; available from Evonik)

The composition of the curable masses produced in this way and the properties measured on these masses are given in the tables below. Table 1: Composition of the curable masses Example C1 V1 V2 C2 V3 V4 C3 V5 V6 V7 component (a1) 39.5 39.5 39.5 39.5 57.5 10.0 41.4 41.4 39.5 41.4 (a2) 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 (a3) 7.2 7.2 7.2 7.2 4.8 7.2 (a4) 2.0 2.0 2.0 2.0 2.0 (a5) 12.7 (b1) 4.4 4.4 4.4 4.4 5.0 3.0 3.0 4.4 3.0 (b2) 10.0 10.0 10.0 (b3) 16.0 (b4) 1.0 (c1) 1.3 1.3 1.3 1.3 1.5 1.3 (d1) 20.0 35.0 35.0 30.0 35.0 (d2) 35.0 35.0 (e1) 13.0 (f1) 1.0 (g1) 0.6 0.6 0.6 0.6 1.0 0.6 0.6 0.6 0.6 0.6 (g2) 35.0 15.0 35.0 (g3) 35.0 (g4) 0.9 Table 2: Mechanical-thermal properties of the hardened masses Measurement Measurand C1 V1 V2 C2 V3 V4 C3 V5 V6 V7 DMTA, train Tg (first turning point E') [°C] 134 127 132 86 121 152 120 117 133 124 T (Onset module drop) [°C] nb 187 192 nb 201 190 nb 196 172 172 T (further turning point) [°C] nb 190 195 nb 204 193 nb 199 174 174 T (Endset module waste,) [°C] nb 196 201 nb 211 200 nb 204 179 180 E' (23°C) [MPa] 3990 2530 2900 4243 2697 3390 4560 2890 1783 2200 E' (Onset) [MPa] nb 41 29 nb 31 183 nb 54 61 79 E' (end set) [MPa] nb 21 9 nb 6 75 nb 17 14 19 Drop E' between Onset-Endset [%] nb 49 69 nb 81 59 nb 69 77 76 DSC Melting point [°C] - - 212 - - - - - 187 (hardened mass) Enthalpy of fusion [J/g] - - 42 - - - - - 33 Tensile shear strength (hardened mass) Al/Al @ RT [MPa] 21.4 22.2 20.1 nb nb 15.9 18.2 18.8 Temperature resistance (St/St) [MPa] 180°C 8.03 3.7 1.54 23.3 25.2 (St/St) [MPa] 220°C 5.67 1.17 1.54 Decrease [°/] 29 68 0 Temperature resistance after thermal storage 180°C after 1000h 180°C 7.25 5.12 220 °C after 1000h 180°C decrease [°/] 5.26 27 1.4 73

Examples V1 and V2 according to the invention contain a partially 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 another step in the DMTA bulk storage modulus curve, which has another inflection point above the glass transition temperature. In the case of examples V1 and V2, the further turning point is at 190 °C and 195 °C, respectively. When the mass is heated beyond the further turning point, this level is exceeded. In examples V1 and V2 according to the invention, in the temperature range between onset and endset of the module drop, the storage module decreases by 49% and 69%, respectively.

Comparative example C1 does not contain any polymeric filler. The DMTA curve of the storage module of comparative example C1 has no further turning point above the glass transition temperature. The mass C1 is therefore not suitable for producing a thermomechanically removable joint in the sense of the invention.

In the temperature range between 180 ° C and 220 ° C, the lap shear strength in a steel-steel bond with the compound V2 according to the invention is reduced by 68%, while the lap shear strength of the compound from comparative example C1 only drops by 29%. V2 has a high temperature strength at 180 °C of 3.7 MPa, whereas at 220 °C the temperature strength is only 1.17 MPa. The temperature resistance at 220 ° C of the mass of Example V2 is therefore 4.8 times lower than that of Comparative Example C1. A joint made with the mass from Example C2 therefore requires significantly less effort during thermomechanical removal than a joint made from the mass from Comparative Example C1. Furthermore, the polymeric filler (d) does not negatively influence the glass transition temperatures of the cured masses and the lap shear strengths at room temperature. The compositions according to the invention are therefore resistant to thermal and mechanical stress.

The mass from comparative example C2 contains an amorphous polymer as a filler. The use of an amorphous filler (g3) instead of a semi-crystalline polymeric filler (d) does not produce any additional drop in storage modulus. In the DMTA measurement, no further turning point occurs above the glass transition temperature. Furthermore, the temperature strengths at 180 °C and at 220 °C do not differ. The mass C2 is therefore also not thermomechanically removable in the sense of the invention.

The composition of Example V3 has a different epoxy resin composition compared to Example V2. The hardened mass of example V3 also shows a further turning point above the glass transition temperature and a drop in the storage modulus by 81% in the temperature range between onset and endset, and can therefore, analogous to the masses of examples V1 and V2, be efficiently removed thermomechanically.

The mass 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 mass can be fixed by irradiation with actinic radiation and then hardened warmly. Due to the use of a semi-crystalline polymeric filler (d), the storage modulus of this mass also has a further turning point in the DMTA curve above the glass transition temperature of the hardened mass. The drop in storage modulus in the temperature range between onset and endset is 59%. This means that the mass of Example V4 can also be removed thermomechanically efficiently.

The compositions of Examples V5 and V7 according to the invention and of Comparative Example C3 contain a combination of different hardeners for epoxy hardening (b). By combining several hardeners, rapid curing at low temperatures can be achieved without further addition of an accelerator (c). The hardened mass from Example V5 shows a further turning point above the glass transition temperature in the temperature range between onset and endset and a decrease in storage modulus by 69%. This means that the mass from example V5 can also be efficiently removed thermomechanically.

The compositions of Examples V6 and V7 according to the invention contain a partially crystalline polyamide as the polymeric filler (d2), the melting point of which is 190 ° C. The drop in storage modulus in the DMTA measurement occurs in a temperature range of 172 - 180 °C, with the further turning point being at a temperature of 174 °C. Efficient removal of the hardened mass is therefore possible at temperatures below 190 °C.

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

1 shows the DMTA curve of the storage modulus of the hardened masses of examples V5 and V7. The glass transition temperature of the resin matrix is shown as an inflection point at 117 °C and 124 °C, respectively. The curves each have a further turning point above the glass transition temperature. This is 199 °C for example V5 and 174 °C for example V7. Accordingly, the amount of the 1st derivative of the storage modulus results in a maximum at the glass transition point and a maximum at the further turning point in the area of the module drop. The storage modulus of masses V5 and V7 drops by 69% and 76%, respectively, in the temperature range between onset and endset.

In the 1 DMTA curve of comparative example C3, also shown, has no further turning 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 a temperature-related softening of the mass. The mass is therefore not resoluble within the meaning of the invention.

QUOTES INCLUDED IN THE DESCRIPTION

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

Cited patent literature

• EP 1096517 A2 [0005]
• WO 1998031738 A1 [0006]
• JP 3808819 B2 [0007]
• US 5872158 A [0008]
• US 20070196612 A1 [0009]
• WO 2021033368 A1 [0010]
• EP 2084205 B1 [0011]
• DE 102018121067 A1 [0059]
• JP 2012153794 A [0070]
• EP 3075736 A1 [0072]
• US 5278257 A [0119]
• EP 3943534 A1 [0122]

Non-patent literature cited

• DIN EN ISO 11357-3:2018-07 [0165]

Claims (10)

Use of a curable mass for producing a component with a thermomechanically removable joint, a coating or a casting, the mass comprising 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 epoxy curing accelerator; (d) at least one polymeric filler in a proportion of 15% by weight or more, based on the total weight of the composition, the polymeric filler being selected from the group of polyamides; (e) optionally one or more radical polymerization curable compounds; (f) optionally at least one radical polymerization initiator; and (g) optionally further additives, where the polymeric filler is present in the mass as an at least partially crystalline solid and the melting point of the polymeric filler is at least 120 ° C. Use after Claim 1 , characterized in that the proportion of the polymeric filler is at least 20% by weight. Use after Claim 1 or 2 , characterized in that the melting point of the filler is in the range from 120 to 300 ° C. Use according to one of the preceding claims, characterized in that the filler has an enthalpy of fusion of at least 40 J/g. 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 µm. Use according to one of the preceding claims, characterized in that the hardened mass has at least one further turning point in the DMTA curve of the storage module above the glass transition temperature. 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. Curable mass for producing a thermomechanically releasable joint, a coating or a casting, the mass 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 epoxy curing accelerator; (d) at least one polymeric filler in a proportion of 20% by weight or more, based on the total weight of the mass, the polymeric filler being selected from the group of polyamides; (e) optionally one or more radical radiation curable compounds; (f) optionally at least one radical polymerization initiator; and (g) optionally further additives, wherein the polymeric filler is present in the mass as an at least partially crystalline solid which has an enthalpy of fusion of 40 J/g or more, and wherein the melting point of the polymeric filler is at least 120 ° C. Method for producing a component using a curable composition according to one of Claims 1 until 8th , the method comprising the following steps: metering the mass onto a first substrate; optionally supplying a further substrate to form a substrate composite, the further substrate being brought into contact with the mass; optionally irradiating the mass with actinic radiation, the irradiated mass achieving a fixing strength which is 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 cured, forming the component with the substrate and a cured adhesive layer connected to the first substrate and optionally the further substrate, the adhesive layer being thermomechanically detachable from the substrate by heating to a predetermined release temperature. Component obtainable by the previous method Claim 9 .

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