DE102020213368A1 - Proton sponges as a catalyst in adhesives and adhesives containing them - Google Patents

Abstract

The invention relates to epoxy-based 1-component and 2-component adhesives which contain at least one proton sponge. The invention also relates to a method for producing a crosslinked adhesive by reacting the components of the two-component adhesive and the crosslinked adhesive obtained therefrom. In addition, the invention relates to an adhesive tape which contains the 1-component adhesive or the crosslinked adhesive according to the present invention. Finally, the present invention relates to the use of a proton sponge as a catalyst for the production of epoxy adhesives.

Description

The invention relates to epoxy-based 1-component and 2-component adhesives which contain at least one proton sponge. The invention also relates to a method for producing a crosslinked adhesive by reacting the components of the two-component adhesive and the crosslinked adhesive obtained therefrom. In addition, the invention relates to an adhesive tape which contains the 1-component adhesive or the crosslinked adhesive according to the present invention. Finally, the present invention relates to the use of a proton sponge as a catalyst for the production of epoxy adhesives.

If you want to carry out reactions in epoxy-containing adhesives (e.g. partial pre-crosslinking), you need basic catalysts for many reactions. Typical non-nucleophilic bases known to those skilled in the art, such as, for example, DBU, are indeed active as catalysts, but always also initiate an anionic polymerization of epoxide groups. This means that targeted reactions in epoxy-containing adhesives without unwanted epoxy-epoxy side reactions are not possible.

The object of the invention is therefore to provide epoxy-based adhesives in which essentially no epoxy-epoxy side reaction takes place and the epoxy resin can therefore already be stored with the catalyst in one component.

Surprisingly, the object was achieved by using proton sponges as a catalyst for the epoxy-based adhesives.

In the prior art, proton sponges are hardly disclosed in connection with adhesives. One of the few examples of this is the US2015232610A1 . However, the person skilled in the art of epoxy adhesives would not have considered this.

• i) mindestens ein Epoxidharz;
• ii) mindestens einen Protonenschwamm;
• iii) mindestens eine Verbindung, welche zur Reaktion mit dem Epoxidharz fähig ist;
• iv) gegebenenfalls eine Filmbildner-Matrix; und
• v) gegebenenfalls mindestens ein Additiv.

Therefore, in a first aspect, the present invention relates to a 1-component epoxy-based adhesive, comprising

• i) at least one epoxy resin;
• ii) at least one proton sponge;
• iii) at least one compound capable of reacting with the epoxy resin;
• iv) optionally a film former matrix; and
• v) optionally at least one additive.

1. A) eine erste Komponente, welche
   • ai) mindestens ein Epoxidharz;
   • aii) mindestens einen Protonenschwamm;
   • aiii) gegebenenfalls eine Filmbildner-Matrix; und
   • aiv) gegebenenfalls mindestens ein Additiv umfasst oder daraus besteht und
2. B) eine zweite Komponente, welche
   • bi) mindestens eine Verbindung, welche zur Reaktion mit dem Epoxidharz fähig ist;
   • bii) gegebenenfalls eine Filmbildner-Matrix; und
   • biii) gegebenenfalls mindestens ein Additiv umfasst oder daraus besteht.

In a second aspect, the present invention relates to a 2-component adhesive, comprising

1. A) a first component, which
   • ai) at least one epoxy resin;
   • aii) at least one proton sponge;
   • aiii) optionally a film former matrix; and
   • aiv) optionally comprises or consists of at least one additive and
2. B) a second component, which
   • bi) at least one compound capable of reacting with the epoxy resin;
   • bii) optionally a film former matrix; and
   • biii) optionally comprises or consists of at least one additive.

In a third aspect, the present invention relates to a method for producing a crosslinked adhesive by reacting component A with component B of the two-component adhesive according to the present invention.

Furthermore, in a fourth aspect, the present invention relates to a crosslinked adhesive obtained by the method according to the present invention.

In addition, in a fifth aspect, the present invention relates to an adhesive tape containing the 1-component adhesive according to the present invention or the crosslinked adhesive according to the present invention.

Finally, in a sixth aspect, the present invention relates to the use of a proton sponge as a catalyst for the production of epoxy adhesives.

"At least one" as used herein refers to 1 or more, for example 2, 3, 4, 5, 6, 7, 8, 9 or more. In the context of components of the compound described herein, this information does not refer to the absolute amount of molecules but to the type of component. Thus, for example, "at least one epoxy resin" means one or more different types of epoxy resins and does not refer to the number of a single type of epoxy resin in the composition.

Numerical values given herein without decimal places refer to the full stated value with one decimal place. For example, "99%" means "99.0%".

The expression "approximately" or "approximately" in connection with a numerical value refers to a variance of ±10% based on the stated numerical value, preferably ±5%, particularly preferably ±1%.

The expression "substantially free from" according to the present invention is to be understood in such a way that the respective compound is present in such small amounts that it has no negative influence on the composition, in particular the respective compound is present in less than 0.5 wt %, preferably 0.1% by weight, even more preferably 0.01% by weight, based on the total weight of the composition. In particular, the respective compound is not contained in the composition at all.

Substituted for the purposes of the present invention refers to radicals, in particular substituted polycyclic aromatic radicals, in which at least one hydrogen atom has been replaced by another atom or radical, preferably by -F, -Cl, -Br, -I, -OH, - _NH2 or _-NO2 .

The term "alkyl" in the context of the present invention includes linear and branched saturated hydrocarbon radicals having up to 12 carbon atoms, preferably up to 6 carbon atoms, more preferably up to 4 carbon atoms, in particular methyl, ethyl, n-propyl, isopropyl, n- butyl, iso-butyl and tert-butyl.

Details of the number-average molar mass Mn or the weight-average molar mass Mw are determined by measurement using gel permeation chromatography (GPC). It was measured against polystyrene standards.

According to the invention, the viscosity is determined as dynamic viscosity as follows. The dynamic viscosity can be determined according to DIN 53019-1-2008-09. The viscosity is measured in a cylinder rotation viscometer with a standard geometry according to DIN 53019-1-2008-09 at a measurement temperature of 23° C. and a shear rate of 1×s ⁻¹ .

The softening temperature is measured according to the invention according to the relevant methodology known as Ring and Ball and standardized under ASTM E28-18. An HRB 754 ring and ball machine from Herzog is used to determine the adhesive resin softening point of the resins. Resin samples are first finely ground. The resultant powder is charged in a bottom-opening brass cylinder (inner diameter at the top of the cylinder 20 mm, diameter of the bottom opening of the cylinder 16 mm, height of the cylinder 6 mm) and melted on a hot stage. The filling quantity is selected in such a way that the resin completely fills the cylinder after melting without protruding. The resulting specimen is placed in the specimen holder of the HRB 754 together with the cylinder. Glycerin is used to fill the temperature control bath if the adhesive resin softening temperature is between 50 °C and 150 °C. A water bath can also be used at lower adhesive resin softening temperatures. The test balls have a diameter of 9.5 mm and weigh 3.5 g. According to the HRB 754 procedure, the sphere is placed above the specimen in the temperature control bath and placed on the specimen. There is a collecting plate 25 mm below the bottom of the cylinder and a light barrier 2 mm above it. During the measurement process, the temperature is increased at 5 °C/min. In the temperature range of the adhesive resin softening point, the ball begins to move through the bottom opening of the cylinder until it finally comes to a standstill on the collecting plate. In this position it is detected by the light barrier and the temperature of the temperature control bath is registered at this point in time. A double determination takes place. The adhesive resin softening point is the average of the two individual measurements.

The static glass transition temperature Tg is determined using differential scanning calorimetry in accordance with DIN 53765:1994-03. For this purpose, approximately 7 mg of the sample are weighed exactly into an aluminum crucible and then introduced into the measuring device (device: DSC 204 F1, Netzsch company). An empty crucible is used as a reference. Two heating curves are then recorded at a heating rate of 10 K/min. The information on the glass transition temperature Tg relates to the glass transition temperature value Tg according to DIN 53765:1994-03 of the second heating curve, unless otherwise specified in individual cases.

Further reference methods result from the following description and, if available, the test methods in the experimental part.

These and other aspects, embodiments, features and advantages of the invention will become apparent to those skilled in the art from a study of the following detailed description and claims. Each feature from one aspect of the invention can be used in any other aspect of the invention. Furthermore, it should be understood that the examples contained herein are intended to describe and illustrate the invention, but not to limit it, and in particular the invention is not limited to these examples.

1. 1. 1-Komponenten-Klebstoff auf Epoxid-Basis, umfassend
   1. i) mindestens ein Epoxidharz;
   2. ii) mindestens einen Protonenschwamm;
   3. iii) mindestens eine Verbindung, welche zur Reaktion mit dem Epoxidharz fähig ist;
   4. iv) gegebenenfalls eine Filmbildner-Matrix; und
   5. v) gegebenenfalls mindestens ein Additiv, oder wobei der Klebstoff aus den vorstehenden Bestandteilen besteht.
2. 2. 1-Komponentenklenstoff gemäß der vorstehenden Ausführungsform, weiterhin umfassend
   • vi) mindestens einen von iii) verschiedenen Härter,
   • vii) gegebenenfalls mindestens einen Beschleuniger,
   wobei die Menge der Komponente iii) insbesondere derart gewählt ist, dass ihre zur Reaktion mit dem Epoxid befähigten Gruppen im Unterschuss zu den Epoxidgruppen des Epoxidharzes vorliegt.
3. 3. 2-Komponenten-Klebstoff, umfassend
   1. A) eine erste Komponente, welche
      • ai) mindestens ein Epoxidharz;
      • aii) mindestens einen Protonenschwamm;
      • aiii) gegebenenfalls eine Filmbildner-Matrix; und
      • aiv) gegebenenfalls mindestens ein Additiv umfasst oder daraus besteht und
   2. B) eine zweite Komponente, welche
      • bi) mindestens eine Verbindung, welche zur Reaktion mit dem Epoxidharz fähig ist;
      • bii) gegebenenfalls eine Filmbildner-Matrix; und
      • biii) gegebenenfalls mindestens ein Additiv umfasst oder daraus besteht; oder wobei der Klebstoff aus den vorstehenden Komponenten besteht.
4. 4. 2-Komponenten-Klebstoff gemäß Ausführungsform 3, dadurch gekennzeichnet, dass die Komponente A) nach Lagerung bei 23°C von einem Monat im Wesentlichen keine Epoxidpolymerisation aufweist, bevorzugt weniger als 5 %, stärker bevorzugt weniger als 3 %, gemessen mittels FT-IR. Wobei die Abnahme der Epoxidschwingung im Vergleich zur ursprünglichen Epoxidschwingung bestimmt wird.
5. 5. Klebstoff gemäß einer der vorstehenden Ausführungsformen, dadurch gekennzeichnet, dass der mindestens eine Protonenschwamm die v allgemeine Formel (I) aufweist
   
   wobei A und B gemeinsam einen substituierten oder unsubstituierten polycyclischen aromatischen Rest bilden; bevorzugt ist der aromatische Rest ein substituierter oder unsubstituierter Rest ausgewählt aus Naphthalen, Acenaphthene, Acenaphthylen, Anthrazen, Pyren, Chrysen, Phenalen, und Phenanthren; wobei R¹ und R² unabhängig voneinander ausgewählt werden aus einem C_1-4 Alkylrest oder R¹ und R² gemeinsam einen Rest =C(Alkyl)₂, =C(N(Alkyl)₂)₂, =C(N(Alkyl)H)₂, =P(N(Alkyl)₂)₃, =P(N(Alkyl)H)₃, =S(=O)(Alkyl)₂, =S(=O)(Phenyl)(Alkyl), insbesondere =C-[(N(CH₃)₂]₂, =P-[N(CH₃)₂]₃, =S(=O)PhenylCH₃ bilden; wobei R³ und R⁴ unabhängig voneinander ausgewählt werden aus einem C_1-4 Alkylrest oder R³ und R⁴ gemeinsam einen Rest =C(Alkyl)₂, =C(N(Alkyl)₂)₂, =C(N(Alkyl)H)₂, =P(N(Alkyl)₂)₃, =P(N(Alkyl)H)₃, =S(=O)(Alkyl)₂, =S(=O)(Phenyl)(Alkyl), insbesondere =C-[(N(CH₃)₂]₂, =P-[N(CH₃)₂]₃, =S(=O)PhCH₃ bilden; oder die allgemeine Formel (II) aufweist
   
   wobei A und B unabhängig ausgewählt sind aus substituierten oder unsubstituierten aromatischen Resten, bevorzugt sind A und B ein substituierter oder unsubstituierter Benzylrest; wobei R¹ und R² unabhängig voneinander ausgewählt werden aus einem C_1-4 Alkylrest oder R¹ und R² gemeinsam einen Rest =C(Alkyl)₂, =C(N(Alkyl)₂)₂, =C(N(Alkyl)H)₂, =P(N(Alkyl)₂)₃, =P(N(Alkyl)H)₃, =S(=O)(Alkyl)₂, =S(=O)(Phenyl)(Alkyl), insbesondere =C-[(N(CH₃)₂]₂, =P-[N(CH₃)₂]₃, =S(=O)PhenylCH₃ bilden; wobei R³ und R⁴ unabhängig voneinander ausgewählt werden aus einem C_1-4 Alkylrest oder R³ und R⁴ gemeinsam einen Rest =C(Alkyl)₂, =C(N(Alkyl)₂)₂, =C(N(Alkyl)H)₂, =P(N(Alkyl)₂)₃, =P(N(Alkyl)H)₃, =S(=O)(Alkyl)₂, =S(=O)(Phenyl)(Alkyl), insbesondere =C-[(N(CH₃)₂]₂, =P-[N(CH₃)₂]₃, =S(=O)PhenylCH₃ bilden; und wobei Z ein Heteroatom ist, insbesondere N, P, S oder O, besonders bevorzugt N oder O; oder die allgemeine Formel (III) aufweist
   
   wobei R¹ und R² unabhängig voneinander ausgewählt sind aus einem C_1-4 Alkylrest.
6. 6. Klebstoff gemäß einer der vorstehenden Ausführungsformen, dadurch gekennzeichnet, dass der mindestens eine Protonenschwamm die allgemeine Formel (la) aufweist
   
   wobei R¹ und R² unabhängig voneinander ausgewählt werden aus einem C_1-4 Alkylrest oder R¹ und R² gemeinsam einen Rest =C(Alkyl)₂, =C(N(Alkyl)₂)₂, =C(N(Alkyl)H)₂, =P(N(Alkyl)₂)₃, =P(N(Alkyl)H)₃, =S(=O)(Alkyl)₂, =S(=O)(Phenyl)(Alkyl), insbesondere =C-[(N(CH₃)₂]₂, =P-[N(CH₃)₂]₃, =S(=O)PhenylCH₃ bilden; wobei R³ und R⁴ unabhängig voneinander ausgewählt werden aus einem C_1-4 Alkylrest oder R³ und R⁴ gemeinsam einen Rest =C(Alkyl)₂, =C(N(Alkyl)₂)₂, =C(N(Alkyl)H)₂, =P(N(Alkyl)₂)₃, =P(N(Alkyl)H)₃, =S(=O)(Alkyl)₂, =S(=O)(Phenyl)(Alkyl), insbesondere =C-[(N(CH₃)₂]₂, =P-[N(CH₃)₂]₃, =S(=O)PhenylCH₃ bilden; oder die allgemeine Formel (IIa) aufweist
   
   wobei R¹ und R² unabhängig voneinander ausgewählt werden aus einem C_1-4 Alkylrest oder R¹ und R² gemeinsam einen Rest =C(Alkyl)₂, =C(N(Alkyl)₂)₂, =C(N(Alkyl)H)₂, =P(N(Alkyl)₂)₃, =P(N(Alkyl)H)₃, =S(=O)(Alkyl)₂, =S(=O)(Phenyl)(Alkyl), insbesondere =C-[(N(CH₃)₂]₂, =P-[N(CH₃)₂]₃, =S(=O)PhenylCH₃ bilden; wobei R³ und R⁴ unabhängig voneinander ausgewählt werden aus einem C_1-4 Alkylrest oder R³ und R⁴ gemeinsam einen Rest =C(Alkyl)₂, =C(N(Alkyl)₂)₂, =C(N(Alkyl)H)₂, =P(N(Alkyl)₂)₃, =P(N(Alkyl)H)₃, =S(=O)(Alkyl)₂, =S(=O)(Phenyl)(Alkyl), insbesondere =C-[(N(CH₃)₂]₂, =P-[N(CH₃)₂]₃, =S(=O)PhenylCH₃ bilden; und wobei Z ausgewählt ist aus N, P, S oder O, insbesondere N oder O.
7. 7. Klebstoff gemäß einer der vorstehenden Ausführungsformen, dadurch gekennzeichnet, dass der mindestens eine Protonenschwamm ausgewählt ist aus 1,8-Bis-(dimethylamino)naphthalin, 1,8-Bis-(tetramethylguanidino)naphthalin, 1,8-Bis-(dimethylenguanidino)naphthalin, 1,8-Bis-(hexamethyliminophosphoranyl)naphthalin, 4,5-Bis(dimethylamino)-fluoren, 4,5-Bis(dimethylamino)-heterofluoren oder Mischungen davon.
8. 8. Klebstoff gemäß einer der vorstehenden Ausführungsformen, dadurch gekennzeichnet, dass der mindestens eine Protonenschwamm in 0,001 bis 5 Gew.-%, bevorzugt 0,01 bis 3 Gew.-%, basierend auf dem Gesamtgewicht des 1-Komponenten-Klebstoffs oder der Komponente A des 2-Komponenten-Klebstoffs enthalten ist.
9. 9. Klebstoff gemäß einer der vorstehenden Ausführungsformen, dadurch gekennzeichnet, dass die mindestens eine Verbindung, welche zur Reaktion mit dem Epoxidharz fähig ist, ausgewählt ist aus Thiolen, Carbonsäuren oder Mischungen davon.
10. 10. Verfahren zur Herstellung eines vernetzten Klebstoffs durch Umsetzen der Komponente A mit der Komponente B des 2-Komponenten-Klebstoffs gemäß einer der Ausführungsformen 2 bis 8.
11. 11. Vernetzter Klebstoff erhalten durch das Verfahren gemäß Ausführungsform 9.
12. 12. Klebeband enthaltend den 1-Komponenten-Klebstoff gemäß einer der Ausführungsformen 1 oder 2 oder 5 bis 9 oder den 2-Komponenten-Klebstoff gemäß einer der Ausführungsformen 3 bis 9, insbesondere in Form von Klebstofffilmen oder den vernetzen Klebstoff gemäß Ausführungsform 11.
13. 13. Vorreagiertes Klebeband gemäß Ausführungsform 12, enthalten den vernetzen Klebstoff gemäß Ausführungsform 11, dadurch gekennzeichnet, dass mindestens 5% der ursprünglichen Epoxidgruppen mit mindestens einer Verbindung, welche zur Reaktion mit dem Epoxidharz fähig ist, insbesondere mit Carboxygruppen oder Thiolgruppen, vorreagiert haben und maximal 50%, bevorzugt maximal 40%, insbesondere zwischen 10% - 25% umgesetzt worden ist und/oder die Funktionalität der mindestens einen Verbindung, welche zur Reaktion mit dem Epoxidharz fähig ist, insbesondere Carboxy- bzw. Thiolgruppen tragenden Reagentien, mindestens 2 beträgt.
14. 14. Verwendung eines Protonenschwamms als Katalysator zur Herstellung von Epoxidklebstoffen.

The present invention therefore relates in particular to:

1. 1. 1-component epoxy-based adhesive, comprising
   1. i) at least one epoxy resin;
   2. ii) at least one proton sponge;
   3. iii) at least one compound capable of reacting with the epoxy resin;
   4. iv) optionally a film former matrix; and
   5. v) optionally at least one additive, or wherein the adhesive consists of the above components.
2. 2. 1-component adhesive according to the above embodiment, further comprising
   • vi) at least one hardener different from iii),
   • vii) optionally at least one accelerator,
   where the amount of component iii) is selected in particular such that its groups capable of reacting with the epoxide are present in less than the epoxide groups of the epoxide resin.
3. 3. 2-component adhesive, comprising
   1. A) a first component, which
      • ai) at least one epoxy resin;
      • aii) at least one proton sponge;
      • aiii) optionally a film former matrix; and
      • aiv) optionally comprises or consists of at least one additive and
   2. B) a second component, which
      • bi) at least one compound capable of reacting with the epoxy resin;
      • bii) optionally a film former matrix; and
      • biii) optionally comprises or consists of at least one additive; or wherein the adhesive consists of the foregoing components.
4. 4. 2-component adhesive according to embodiment 3, characterized in that component A) has essentially no epoxide polymerization after storage at 23° C. for one month, preferably less than 5%, more preferably less than 3% as measured by FT-IR. The decay of the epoxy vibration compared to the original epoxy vibration is determined.
5. 5. Adhesive according to one of the preceding embodiments, characterized in that the at least one proton sponge has the v general formula (I).
   
   where A and B together form a substituted or unsubstituted polycyclic aromatic radical; preferably the aromatic radical is a substituted or unsubstituted radical selected from naphthalene, acenaphthene, acenaphthylene, anthracene, pyrene, chrysene, phenalene, and phenanthrene; wherein R ¹ and R ² are independently selected from C _1-4 alkyl or R ¹ and R ² together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl )H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl) , in particular =C-[(N(CH ₃ ) ₂ ] ₂ , =P-[N(CH ₃ ) ₂ ] ₃ , =S(=O)phenylCH ₃ where R ³ and R ⁴ are independently selected from a C _1-4 alkyl radical or R ³ and R ⁴ together a radical =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl)H) ₂ , =P(N(alkyl ) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl), especially =C-[(N(CH ₃ ) ₂ ] ₂ , =P-[N(CH ₃ ) ₂ ] ₃ , =S(=O)PhCH ₃ , or has the general formula (II).
   
   wherein A and B are independently selected from substituted or unsubstituted aromatic radicals, preferably A and B are a substituted or unsubstituted benzyl radical; wherein R ¹ and R ² are independently selected from C _1-4 alkyl or R ¹ and R ² together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl )H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl) , in particular =C-[(N(CH ₃ ) ₂ ] ₂ , =P-[N(CH ₃ ) ₂ ] ₃ , =S(=O)phenylCH ₃ where R ³ and R ⁴ are independently selected from a C _1-4 alkyl radical or R ³ and R ⁴ together a radical =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl)H) ₂ , =P(N(alkyl ) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl), especially =C-[(N(CH ₃ ) ₂ ] ₂ , =P-[N(CH ₃ ) ₂ ] ₃ , =S(=O)phenylCH ₃ and where Z is a heteroatom, especially N, P, S or O, more preferably N or O; or has the general formula (III).
   
   wherein R ¹ and R ² are independently selected from C _1-4 alkyl.
6. 6. Adhesive according to one of the preceding embodiments, characterized in that the at least one proton sponge has the general formula (Ia).
   
   wherein R ¹ and R ² are independently selected from C _1-4 alkyl or R ¹ and R ² together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl )H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl) , in particular =C-[(N(CH ₃ ) ₂ ] ₂ , =P-[N(CH ₃ ) ₂ ] ₃ , =S(=O)phenylCH ₃ where R ³ and R ⁴ are independently selected from a C _1-4 alkyl radical or R ³ and R ⁴ together a radical =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl)H) ₂ , =P(N(alkyl ) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl), especially =C-[(N(CH ₃ ) ₂ ] ₂ , =P-[N(CH ₃ ) ₂ ] ₃ , =S(=O)phenylCH ₃ , or has the general formula (IIa).
   
   wherein R ¹ and R ² are independently selected from C _1-4 alkyl or R ¹ and R ² together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl )H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl) , in particular =C-[(N(CH ₃ ) ₂ ] ₂ , =P-[N(CH ₃ ) ₂ ] ₃ , =S(=O)phenylCH ₃ where R ³ and R ⁴ are independently selected from a C _1-4 alkyl radical or R ³ and R ⁴ together a radical =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl)H) ₂ , =P(N(alkyl ) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl), especially =C-[(N(CH ₃ ) ₂ ] ₂ , =P-[N(CH ₃ ) ₂ ] ₃ , =S(=O)phenylCH ₃ bil the; and where Z is selected from N, P, S or O, especially N or O.
7. 7. Adhesive according to one of the preceding embodiments, characterized in that the at least one proton sponge is selected from 1,8-bis(dimethylamino)naphthalene, 1,8-bis(tetramethylguanidino)naphthalene, 1,8-bis(dimethyleneguanidino). )naphthalene, 1,8-bis(hexamethyliminophosphoranyl)naphthalene, 4,5-bis(dimethylamino)fluorene, 4,5-bis(dimethylamino)heterofluorene, or mixtures thereof.
8. 8. Adhesive according to one of the preceding embodiments, characterized in that the at least one proton sponge in 0.001 to 5% by weight, preferably 0.01 to 3% by weight, based on the total weight of the 1-component adhesive or the component A of the 2-component adhesive is included.
9. 9. Adhesive according to one of the preceding embodiments, characterized in that the at least one compound capable of reacting with the epoxy resin is selected from thiols, carboxylic acids or mixtures thereof.
10. 10. A method for producing a crosslinked adhesive by reacting component A with component B of the two-component adhesive according to one of embodiments 2 to 8.
11. 11. Crosslinked adhesive obtained by the method according to embodiment 9.
12. 12. Adhesive tape containing the 1-component adhesive according to one of embodiments 1 or 2 or 5 to 9 or the 2-component adhesive according to one of embodiments 3 to 9, in particular in the form of adhesive films or the crosslinked adhesive according to embodiment 11.
13. 13. Pre-reacted adhesive tape according to embodiment 12, containing the crosslinked adhesive according to embodiment 11, characterized in that at least 5% of the original epoxy groups have pre-reacted with at least one compound capable of reacting with the epoxy resin, in particular with carboxy groups or thiol groups, and at most 50%, preferably a maximum of 40%, in particular between 10% and 25%, has been converted and/or the functionality of the at least one compound which is capable of reacting with the epoxy resin, in particular reagents bearing carboxyl or thiol groups, is at least 2.
14. 14. Use of a proton sponge as a catalyst for the production of epoxy adhesives.

The inventors of the present invention have surprisingly found that proton sponges can be used in epoxy-based adhesives as catalysts, which are also referred to as activators in the prior art, and thus lead, among other things, to improved shelf life of the adhesives at room temperature. The epoxy-based adhesive is not limited and can be available as a 1-component or 2-component adhesive. The adhesives can be used in the form of liquid adhesives - both in the variant as a 1-component adhesive and in the variant as a 2-component adhesive. This has the advantage of being able to intimately mix the components. The adhesives can also be present as part of adhesive tapes, the adhesives then being present as films. In an advantageous embodiment, such films contain a film former matrix. Such embodiments are known to those skilled in the art. For example, suitable embodiments and manufacturing methods are in the DE 10 2013 222 739 , DE 10 2019 209 513 and DE 10 2015 225 854 disclosed, to whose embodiments and production methods reference is hereby explicitly made.

In a further embodiment, the adhesives according to the invention are suitable for producing pre-crosslinked adhesive films, in particular the 1-component adhesives. Advantageously, the procedure is such that sub-component iii), namely the at least one compound which is capable of reacting with the epoxy resin, is present in less than the epoxy groups of sub-component (i), namely the epoxy resin, so that pre-crosslinking of the Adhesive can be done by means of these two components. As explained above, the proton sponges catalyze this reaction, but do not lead to epoxide-epoxide side reactions, so that the pre-crosslinking up to the desired degree of crosslinking—given by the ratio of the partial components i) and iii) to one another—can be operated. In this embodiment variant, at least one further hardener, different from the proton sponges, is preferably added to the adhesive as partial component vi), via which further hardening of the adhesive can take place later, up to full hardening. Adhesive films can thus be produced which, even without a matrix polymer, have sufficient cohesion to be able to exist as a self-supporting film, due to the pre-crosslinking by means of the proton foam-catalyzed reaction of the subcomponents i) and iii), and which in two th crosslinking step of component i), of the epoxy resin, by means of sub-component vi), namely the additional hardener, can be further cured or cured.

The adhesives according to the invention contain at least one epoxy resin. According to the invention, an epoxy resin and / or a mixture of different epoxy resins is suitable, such as. B. monomeric or polymeric, aliphatic, cycloaliphatic or aromatic epoxides. These materials generally have an average of at least two epoxide groups per molecule, preferably more than two epoxide groups per molecule. The "average" number of epoxy groups per molecule is defined as the number of epoxy groups in the epoxy-containing material divided by the total number of epoxy molecules present. The polymeric epoxides include linear epoxide-terminated polymers (e.g., a diglycidyl ether of a polyoxyalkylene glycol), polymers having backbone oxirane units (e.g., polybutadiene polyepoxide), and polymers having pendant epoxy groups (e.g., a glycidyl methacrylate polymer or copolymer). The molecular weight, preferably weight average molecular weight, of the epoxide-containing material can vary from 58 to about 100,000 g/mol or more.

Useful epoxy resins include those containing cyclohexene oxide groups, particularly epoxy cyclohexane carboxylates such as e.g. B. 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-2-methylcyclohexylmethyl-3,4-epoxy-2-methylcyclohexanecarboxylate and bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate. Other epoxy resins useful in the present invention are glycidyl ethers of polyhydric phenols obtained by reacting a polyhydric phenol with an excess of a chlorohydrin such as epichlorohydrin (e.g. the diglycidyl ether of 2,2-bis(2,3-epoxypropoxyphenol)propane) , are obtained. Further examples of epoxides of this type which can be used in the application of this invention are in U.S. Patent No. 3,018,262 described.

There are a variety of commercially available epoxy resins that can be used in this invention. In particular: octadecylene oxide, epichlorohydrin, styrene oxide, vinylcyclohexene oxide, glycidol, glycidyl methacrylate, diglycidyl ether of bisphenol A (e.g. those sold under the trade names EPON 828, EPON 1004 and EPON 1001F from Shell Chemical Co. and DER-332 and DER-334 from Dow Chemical Co.), diglycidyl ether of bisphenol F (e.g. ARALDITE GY281 from Ciba-Geigy), vinylcyclohexene dioxide (e.g. ERL 4206 from Union Carbide Corp.), 3,4-epoxycyclohexylmethyl -3,4-epoxycyclohexene carboxylate (e.g. ERL-4221 from Union Carbide Corp.), 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-metadioxane (e.g. ERL-4234 from Union Carbide Corp.), bis(3,4-epoxycyclohexyl)adipate (e.g. ERL-4299 from Union Carbide Corp.), dipentene dioxide (e.g. ERL-4269 from Union Carbide Corp.), epoxidized polybutadiene (e.g. OXIRON 2001 from FMC Corp.), silicone resin containing epoxy functionality, epoxy silanes (e.g. beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and gamma-glycidoxypropyltrim ethoxysilane commercially available from Union Carbide), fire retardant epoxies (e.g. e.g., DER-542, a brominated bisphenol-type epoxy resin available from Dow Chemical Co.), 1,4-butanediol diglycidyl ether (e.g., ARALDITE RD-2 from Ciba-Geigy), hydrogenated bisphenol A epichlorohydrin-based epoxy resins (e.g EPONEX 1510 from Shell Chemical Co.) and polyglycidyl ether of phenol formaldehyde novolak (e.g. DEN-431 and DEN-438 from Dow Chemical Co.).

In one embodiment, the at least one epoxy resin has a Tg of -100 to 60°C, preferably -50 to 40°C.

In one embodiment, the at least one epoxy resin has an average functionality of 2 to 15, preferably 2 to 7.

In one embodiment, the at least one epoxy resin has a softening point of at least 45°C. This is particularly the case in embodiments where the proportion of low-viscosity polyetheramine in the blend increases.

In one embodiment, the at least one epoxy resin or at least one epoxy resin contained has a viscosity at 25° C. of at least 20 Pa*s, preferably 50 Pa*s, more preferably 150 Pa*s.

In one embodiment, at least one, preferably two, epoxy resin(s) that is liquid at 23° C. and at least one epoxy resin that is solid at 23° C. are present.

Particular preference is given to using epoxy resins—particularly advantageously in combination with one or more elastomer-modified and/or silane-modified and/or fatty acid-modified epoxy resins—as epoxy resins.

Elastomer-modified epoxides in the context of the present invention are—particularly liquid, generally highly viscous—epoxides with an average functionality of at least two and an elastomer content of up to 50% by weight, preferably from 5 to 40% by weight. , to understand. The epoxide groups can be located terminally and/or in the side chain of the molecule. The elastomeric structural part of these flexibilized epoxides consists of polyenes, diene copolymers and polyurethanes, preferably of polybutadiene, butadiene-styrene or butadiene-acrylonitrile copolymers.

A butadiene-acrylonitrile copolymer (nitrile rubber)-modified epoxy resin is, for example, an epoxy prepolymer obtained by modifying an epoxy resin having at least two epoxy groups in the molecules with a nitrile rubber. A reaction product of glycerin or propylene glycol and a halogen-containing epoxy compound such as epichlorohydrin or the reaction product of a polyhydric phenol such as hydroquinone, bisphenol-A and a halogen-containing epoxy is advantageously used as the epoxy base. A reaction product of a bisphenol A type epoxy resin having diepoxide end groups is desirable.

In the case of butadiene polymers or butadiene-acrylonitrile copolymers (so-called nitrile rubbers), a third monomer with an acid function - for example acrylic acid - can also be polymerized in to bind the epoxy resins, resulting in so-called carboxy-terminated nitrile rubbers (CTBN). As a rule, these compounds contain acid groups not only at the ends, but also along the main chain. For example, CTBNs are sold under the Hycar tradename by B.F. Goodrich. These have molar masses between 2000 and 5000 g/mol and acrylonitrile contents between 10% and 30%. Specific examples are Hycar CTBN 1300×8, 1300×13 or 1300×15. The reaction with butadiene polymers proceeds accordingly.

So-called epoxy-terminated nitrile rubbers (ETBN), which are particularly preferably used for this invention, are obtained by reacting epoxy resins with CTBN. Such ETBNs are commercially available, for example, from Emerald Materials under the name HYPRO ETBN (formerly Hycar ETBN) - such as Hypro 1300X40 ETBN, Hypro 1300X63 ETBN and Hypro 1300X68 ETBN. An example of an epoxy terminated butadiene rubber is Hypro 2000X174 ETB.

Other examples of elastomer-modified epoxy-functional compounds are a reaction product of a diglycidyl ether of neopentyl alcohol and a carboxyl-terminated butadiene/acrylonitrile elastomer (e.g., EPON™ Resin 58034 from Resolution Performance Products LLC), a reaction product of a diglycidyl ether of bisphenol-A and a butadiene /acrylonitrile carboxyl-terminated elastomer (e.g., EPON™ Resin 58006 from Resolution Performance Products LLC), a butadiene/acrylonitrile carboxyl-terminated elastomer (e.g., CTBN-1300X8 and CTBN-1300X13 from Noveon, Inc., Cleveland, Ohio) and an amine-terminated butadiene/acrylonitrile elastomer (e.g., ATBN-1300X16 and ATBN-1300X42 from Noveon, Inc.). An example of the elastomer-modified epoxy resin adduct is the reaction product of a bisphenol F-based epoxy resin and a carboxyl-terminated butadiene/acrylonitrile elastomer (e.g., EPON™ Resin 58003 from Resolution Performance Products LLC).

The proportion of elastomer-modified epoxy resins, based on the total amount of epoxy resins, can be between 0 and 100% by weight. For bonds with particularly high bond strengths and low elongation, lower proportions—for example 0 to 15% by weight—are chosen. In contrast to this, adhesives with high elongation values are obtained when the proportion is greater than 40% by weight, in particular greater than 60% by weight. A balance between bond strength and elongation is desirable for many applications. Proportions between 20 to 60% by weight, in particular 30 to 50% by weight, are preferred here. Depending on the requirement profile, it can also be advantageous to use adhesives with a proportion of up to 100%.

In order to achieve sufficient crosslinking in the pre-crosslinking step, preference is given to using epoxy resins which have a functionality of at least 2 (f≥2). The addition of epoxy resins with higher functionality (f>2) is helpful to achieve pre-crosslinking and to keep conversion as low as possible, which is important for good tack. Often these higher functionality resins are solids such as epoxy novolaks.

Alternatively, liquid higher-functionality epoxy resins can make up up to 100% by weight of the epoxy resin mixture.

In order to achieve good bonding properties in the cured adhesive composition, it preferably contains no more than 70% by weight of liquid epoxy resins. A preferred amount of higher functional solid resins in the epoxy resin mixture is between 10% by weight and 70% by weight, in particular less than 50%. If monofunctional epoxy resins such as butyl glycidyl ether, cresyl glycidyl ether or other alkyl glycidyl ethers are used, their proportion of the total amount of epoxy resins is not greater than 15% by weight, preferably 10% by weight, in particular less than 5% by weight, based on the total weight of the contained epoxy resins.

In a preferred embodiment, the at least one epoxy resin is present in 60 to 99% by weight based on the total weight of epoxy resin and the at least one compound capable of reacting with epoxy resins. In a more preferred embodiment, the at least one epoxy resin is present at 85 to 99% by weight based on the total weight of epoxy resin and the at least one compound capable of reacting with epoxy resins, particularly when the one compound capable of reacting with epoxy resins is an equivalent weight smaller 1000g/eq. In an alternative more preferred embodiment, the at least one epoxy resin is present in 60 to 90% by weight based on the total weight of epoxy resin and the at least one compound capable of reacting with epoxy resins, especially when the one is capable of reacting with epoxy resins Compound is a difunctional compound.

The adhesives of the present invention also contain at least one proton sponge. In general, all proton sponges known to those skilled in the art are suitable. Preferred proton sponges are described above.

The adhesives of the present invention also contain at least one compound capable of reacting with the epoxy resin. Thiols, carboxylic acids or mixtures thereof are particularly suitable.

In one embodiment, the at least one thiol has a number-average molecular weight Mn of 50 to 2500 g/mol.

The at least one thiol is preferably selected from pentaerythritol tetra-(3-mercaptopropionate) CAS: 7575-23-7, trimethylolpropane tris-(3-mercaptopropionate) CAS: 33007-83-9, tris-[2-(3- mercaptopropionyloxy)ethyl]isocyanurate CAS: 36196-44-8, glycol di-(3-mercaptopropionate) CAS: 22504-50-3, di-pentaerythritolhexy-(3-mercaptopropionate) CAS: 25359-71-1 and polymeric mercaptopropionates from ethoxylated trimethylolpropane tris-(3-mercaptopropionate) CAS: 674786-83-5 and 345352-19-4, polycaprolactone tetra-(3-mercaptopropionate) CAS: 1622079-69-9 or mixtures thereof; is selected in particular from trimethylolpropane tris-(3-mercaptopropionate) or alkoxylated, in particular ethoxylated, trimethylolpropane tris-(-3-mercaptopropionate) or mixtures thereof.

In order to obtain stable, pre-reacted adhesives, in a preferred embodiment the amount of thiol depends on the amount of epoxy groups which results from the mixture EEW (epoxy equivalent) of the epoxy resins used. Preferably between 0.1 and 0.5 equivalents of thiol groups, in particular between 0.15 and 0.3 and in particularly preferred embodiments between 0.15 and 0.25 equivalents are selected per equivalent of epoxide groups. In this way, pre-reacted adhesives are obtained which, depending on the choice of epoxy resin system and precise pre-reaction conversion, can also produce pressure-sensitively adhesive films.

Preferred carboxylic acids have at least a functionality of 1.8 (e.g. dicarboxylic acids). Typical examples of suitable dicarboxylic acids are, for example, adipic acid, azelaic acid, sebacic acid or 1,12-dodecanedioic acid. Adipic acid and 1,12-dodecanedioic acid are very particularly preferred.

Also suitable are carboxyl-functionalized butadiene polymers, so-called CTB, or carboxyl-functionalized butadiene-acrylonitrile copolymers, so-called CTBN. These are commercially available from e.g.

In a preferred embodiment of the invention, the adhesives according to the invention additionally have a hardener that differs from the other components. In the 1-component variant, this differs in particular from component ii), namely the at least one compound which is capable of reacting with the epoxy resin. The amount of component ii), namely the at least one compound which is capable of reacting with the epoxy resin, is preferably selected in excess such that the epoxy resin of component i) is only partially consumed in the reaction with component iii). As a result, the epoxy resin can be pre-crosslinked by reaction with component iii) without it being completely consumed. The other epoxy resin that is still present can then be crosslinked in a further crosslinking or curing step with component vi), namely the hardener, which differs from the other components. Thus, after the first crosslinking step, a pre-crosslinked adhesive is obtained, the cohesion of which is already increased and which can thus be formed, for example, into an adhesive film, in particular a self-supporting one. This adhesive film can be crosslinked or cured in the second crosslinking step, for example to achieve the full bond strength as an adhesive film when joining two substrates to one another.

The hardeners vi) used, which differ from the other components, can advantageously be latent hardeners, ie hardeners that are first converted into a reactive form. Suitable (latent) hardeners vi) essentially do not react in the pre-crosslinking step, ie in the first crosslinking.

Such hardeners vi) are referred to in this document according to DIN 55945: 1999-07 as the chemical compound(s) acting as a binder, which is (are) added to the crosslinkable resins in order to facilitate the final hardening ( Crosslinking) of the curable composition, in particular in the form of an applied film to bring about. The compositions of the present invention may also optionally contain at least one accelerator.

In the context of this document, (latent) accelerators vii) refer to those chemical compounds which, in the presence of another hardener vi), increase the reaction rate of the curing reaction and/or the rate of activation of the curing of the epoxy resins, in particular in terms of a synergism.

In principle, curing reactions can be identified as an exothermic peak in differential scanning calorimetry (DSC). The measuring method according to DIN 53765:1994-03 is used. The temperature at the maximum of this exothermic peak at a heating rate of 10K/min used is referred to as T _peak .

Accelerator is to be understood in particular as meaning those compounds whose addition shifts the curing peak of a specific curing agent to lower temperatures.

In contrast to the individual hardeners and accelerators, the term hardening reagent refers to all of the hardeners and accelerators used for the hardening reaction by means of the corresponding reactive component (the corresponding reactive resin(s)). In the present invention, the hardening reagent can accordingly be formed in particular from one or more hardeners and the proton sponge or from one or more hardeners and the proton sponge in the presence of one or more accelerators.

Particularly advantageous compounds from the following list consisting of dicyandiamide, anhydrides, epoxy-amine adducts, phenol novolaks, cresol novolaks, hydrazides and reaction products of diacids and multifunctional amines can be selected as hardeners vi). Examples of reaction products from diacids and multifunctional amines are reaction products from phthalic acid and diethylenetriamine. In a very preferred embodiment of the invention, the curing agent comprises dicyandiamide and one or more imidazole compounds (e.g. selected from the Curezol series available from Evonik Industries AG).

In a preferred embodiment, the at least one hardener vi) which is different from the other components is selected from dicyandiamides, phenol novolaks, cresol novolaks, anhydrides, epoxy-amine adducts, hydrazides or mixtures thereof.

In one embodiment, the at least one hardener vii) has a T _peak , determined using DSC as described above, of more than 60°C, preferably more than 80°C, in particular more than 100°C.

In a preferred embodiment, the proportion of the at least one further hardener vi) that differs from the other components is determined via the epoxide equivalent weight (EEW) of the epoxide mixture and the amine equivalent weight (AHEW). It has been shown here that, particularly when using dicyandiamide as a hardener, at least 90% of the theoretically required amount of amine is preferred, but it is also possible to use significantly more than the equimolar amount, for example 130%, 150% or 200%.

wobei
m_ges = Summe m_i
m_i Massen der einzelnen Komponenten i der Mischung
EEW_i = Epoxyäquivalente der Komponenten iStoichiometric hardeners such as dicyandiamide are preferably used based on the amount of epoxide in the adhesive. To do this, the EEW of the epoxy mixture is first calculated using the following formula: $${\text{EEW}}_{\text{total}}=\raisebox{1ex}{${\text{m}}_{\text{total}}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{\Sigma }\frac{{\text{m}}_{\text{i}}}{{\text{EEW}}_{\text{i}}}$}\right.$$

whereby
m _tot = sum m _i
m _i masses of the individual components i of the mixture
EEW _i = epoxy equivalents of components i

The amount of hardener m _H then results from the amine equivalent of the hardener (AHEW) and the _total EEW of the epoxy mixture as follows: $${\text{m}}_{\text{H}}\text{=AHEW*}\left({\text{m}}_{\text{i}}{\text{/EEW}}_{\text{total}}\right)$$

The amount of component iii) used, namely the at least one compound which is capable of reacting with the epoxy resin, must be taken into account in the calculation, since this already converts part of the epoxy groups, resulting in a reduced amount of hardener for vi). This is shown in an example: For pre-crosslinking, an epoxide conversion of 15% is achieved and a corresponding amount of component iii) is used. The amount of hardener is reduced accordingly by 15%.

For epoxy-amine adducts, it is preferred that between 10% by weight and 30% by weight of vi) are used, based on the weight of the at least one epoxy resin i).

In one embodiment, the accelerator vii) is selected from urea derivatives, such as those sold under the trade name Dyhard UR by Alzchem, or imidazoles, such as those available under the trade name Curezol by Evonik Industries AG, or epoxy-amine adducts, such as those sold by Ajinomoto sold under the tradename Ajicure. Particularly preferred urea derivatives are dimethylurea derivatives such as Dyhard UR500 or Dyhard UR700. Preferred imidazoles that give adequate storage stability are, for example, in WO 2019101918 A1 described and explicitly listed here as preferred compounds. Suitable epoxy-amine adducts are in US 6,838,170 B2 disclosed under the generic term "adducts", as well as in US 9,589,693 B2 under the term "amine-epoxy adducts".

In a preferred embodiment, the at least one optional accelerator is used at 0.25% by weight and 5% by weight, based on the weight of the at least one epoxy resin i).

Furthermore, the adhesives can contain a film-forming matrix, particularly if they are in the form of a film. In particular, films made from pre-crosslinked adhesives can also be present in the absence of a film-forming matrix. Suitable film former matrices for use in the present invention are preferably selected from the following list: a thermoplastic polymer, such as a polyester or copolyester, a polyamide or copolyamide, a polyacrylic acid ester, an acrylic acid ester copolymer, a polymethacrylic acid ester, a methacrylic acid ester Copolymer, thermoplastic polyurethanes and chemically or physically crosslinked substances of the aforementioned compounds. In addition, blends of different thermoplastic polymers can also be used.

Furthermore, elastomers and thermoplastic elastomers alone or in a mixture are conceivable as a polymeric film-forming matrix. Thermoplastic polymers, in particular semi-crystalline, are preferred.

Thermoplastic polymers with softening temperatures below 100° C. are particularly preferred. In this context, the term softening point stands for the temperature above which the thermoplastic granulate sticks to itself. If the component of the polymeric film-forming matrix is a semi-crystalline thermoplastic polymer, then it very preferably has a glass transition temperature of at most 25° C., preferably at most 0° C., in addition to its softening point (which is related to the melting of the crystallites).

According to the invention, the amount of the polymeric film-forming matrix is in the range of about 20-80% by weight, preferably about 30-50% by weight, based on the total mixture of the components of the adhesive or the reactive adhesive film. It is most preferred to use 35-45% by weight, preferably about 40% by weight, of the polymeric film-forming matrix, based on the total mixture of the components of the adhesive or of the reactive adhesive film.

The adhesives of the present invention may further contain at least one additive. Suitable additives are, for example, free-radical initiators, fillers, dyes, nucleating agents, rheological additives, blowing agents, adhesion-promoting additives (adhesion promoters, tackifier resins), compounding agents, plasticizers and/or ageing, light and UV protection agents, for example in the form of primary and secondary antioxidants.

Accordingly, the invention particularly preferably relates to an adhesive tape in which the adhesive layer is formed by the 1-component adhesive mentioned, as explained above. These are preferably single-layer adhesive tapes made from the adhesive layer mentioned, which may have a further temporary backing layer for handling, which is removed for use.

In one embodiment, the 2-component adhesive can be present as two adhesive films. In particular, component A) is then present as a reactive adhesive film and component B) as a second adhesive film and thus form an adhesive film system. The two adhesive films crosslink and harden as soon as they are brought into planar contact under moderate pressure, in particular 0.5 to 3 bar, at temperatures in the range from room temperature to 100.degree. Said moderate pressure should be in particular by hand. According to the invention, the contact time is from a few minutes to a few hours, depending on the temperature. The pressure can be applied mechanically or manually.

If the two adhesive films are previously applied to the substrates to be bonded, the above-described crosslinking results in permanent bonding of the substrates. Alternatively, adhesive film (A) can first be applied to the first substrate to be bonded and adhesive film (B) can be applied to adhesive film (A). Then the second substrate to be bonded is then applied to adhesive film (B).

An alternative embodiment relates to an adhesive film system that contains two reactive adhesive films, for example component (A) of the 2-component adhesive described above, or two films of the 1-component adhesive. An impermeable separating layer is provided between the adhesive films that are to be brought into contact with one another for the reaction, so that the activation of the adhesive film system is initially prevented. The separating layer can in particular be a metal layer. This can be a metal foil that is inserted between the adhesive films during the manufacture of the adhesive tape; for example by a lamination process. The separating layer can also be implemented by vapor deposition, sputtering, electrostatic coating or other application of the separating layer material in small, atomic, ionic or molecular form, specifically metals, metal oxides or the like. This can be done, for example, on one of the adhesive films before the other adhesive film is laminated or coated on, or also on both adhesive films on the respective surfaces which subsequently face one another. In the case of multilayer systems, which are constructed in particular in an alternating sequence of first and second adhesive films, a release coating can also be applied to one side of the adhesive films in question, for example, and the lamination can then be carried out in such a way that one uncoated side is placed on a coated side of the adjacent one Adhesive film is brought.

Furthermore, the adhesive film system of the invention can include other films, layers, adhesives and permanent and/or temporary carriers.

Suitable support materials are known to a person skilled in the art. For example, films (polyester, PET, PE, PP, BOPP, PVC, polyimide), nonwovens, foams, fabrics can be used as permanent carriers and/or fabric foils can be used. Temporary carriers should be provided with a separating layer, whereby the separating layer usually consists of a silicone release lacquer or a fluorinated release lacquer or has a polyolefinic character (HDPE, LDPE).

It may be necessary for the surfaces of the substrates to be bonded to be pretreated by a physical, chemical and/or physico-chemical process. Here, for example, the application of a primer or an adhesion promoter composition is advantageous.

Suitable substrates which are suitable for bonding via the reactive adhesive film system according to the invention are metals, glass, wood, concrete, stone, ceramics, textiles and/or plastics. The substrates to be bonded can be the same or different.

In a preferred embodiment, the adhesive film system according to the invention is used for bonding metals, glass and plastics. In a particularly preferred embodiment of the invention, polycarbonates and anodized aluminum are bonded.

The metal substrates to be bonded can generally be made from all common metals and metal alloys. Metals such as aluminum, stainless steel, steel, magnesium, zinc, nickel, brass, copper, titanium, ferrous metals and alloys are preferably used. The parts to be bonded can also be made of different metals.

Suitable plastic substrates are, for example, acrylonitrile butadiene styrene copolymers (ABS), polycarbonates (PC), ABS/PC blends, PMMA, polyamides, glass fiber reinforced polyamides, polyvinyl chloride, polyvinylene fluoride, cellulose acetate, cycloolefin copolymers, liquid crystal polymers (LCP), polylactide , polyetherketones, polyetherimide, polyethersulfone, polymethacrylmethylimide, polymethylpentene, polyphenylether, polyphenylene sulfide, polyphthalamide, polyurethanes, polyvinyl acetate, styrene-acrylonitrile copolymers, polyacrylates or polymethacrylates, polyoxymethylene, acrylic ester-styrene-acrylonitrile copolymers, polyethylene, polystyrene, polypropylene and/or polyesters, such as e.g. polybutylene terephthalate (PBT) and/or polyethylene terephthalate (PET).

Substrates can be coated, printed, vaporized or sputtered.

The substrates to be bonded can take any form required for the use of the resulting composite. In the simplest form, the substrates are planar. In addition, three-dimensional substrates that are inclined, for example, can also be bonded with the reactive adhesive film system according to the invention. The substrates to be bonded can also take on a wide variety of functions, such as housings, viewing windows, stiffening elements, etc.

Process for producing an adhesive film

• In einem ersten Schritt werden die Inhaltsstoffe in einem oder mehreren Lösemittel(n) und/oder Wasser gelöst bzw. fein verteilt. Alternativ ist kein Lösemittel und/oder Wasser notwendig, da die Inhaltsstoffe bereits vollständig ineinander löslich sind (ggf. unter Einwirkung von Wärme und/oder Scherung). Geeignete Lösemittel sind im Stand der Technik bekannt, wobei bevorzugt Lösemittel eingesetzt werden, in denen mindestens einer der Inhaltsstoffe eine gute Löslichkeit aufweist. Besonders bevorzugt ist Aceton.

The adhesive films according to the invention can be produced by the method described below:

• In a first step, the ingredients are dissolved or finely divided in one or more solvent(s) and/or water. Alternatively, no solvent and/or water is necessary since the ingredients are already completely soluble in one another (possibly under the influence of heat and/or shear). Suitable solvents are known in the prior art, preference being given to using solvents in which at least one of the ingredients has good solubility. Acetone is particularly preferred.

The dissolved or finely divided ingredients are then mixed in a second step. Conventional stirrers are used to prepare the mixture. If necessary, the solution is also heated. If necessary, the ingredients are dissolved or finely divided and mixed at the same time.

In a third step, a release paper, a carrier material or a pressure-sensitive adhesive is then coated with the mixture of the dissolved or finely divided ingredients from step 2. The coating is carried out according to the usual techniques which are known in the prior art.

After coating, the solvent is removed in a fourth step by evaporation.

If necessary, the adhesive film can be wound up into a roll in a further step.

For storage, the adhesive films according to the invention are covered with a release liner or paper.

Alternatively, the adhesive films according to the invention are produced without solvents by extrusion, hot-melt nozzle coating or calendering.

examples

Raw materials used:

Hypro 1300X8 CTBN Carboxyl-funktionelles Butadien Copolymer mit 18% Acrylnitril-Comonomer. Viskosität laut Datenblatt 135000 cps, Funktionalität 1,9, Molekulargewicht 3550 g/mol.
DICY (Dyhard 100S, Latenter Härter der Firma AlzChem für Epoxidsysteme bestehend aus mikronisiertem Dicyandiamid bei dem 98 % der Partikel kleiner 10 µm sind.)
Dyhard UR500 Latenter Uronbeschleuniger für Epoxidsysteme bei dem 98 % der Partikel kleiner 10 µm sind.PD3691 Nitrile rubber-modified epoxy resin based on bisphenol A diglycidyl ether with an elastomer content of 5% by weight and a weight per epoxy of 205 g/eq from Schill + Seilacher "Struktol". Viscosity at 25 °C of 300 Pa s.

Hypro 1300X8 CTBN Carboxyl functional butadiene copolymer with 18% acrylonitrile comonomer. Viscosity according to data sheet 135000 cps, functionality 1.9, molecular weight 3550 g/mol.
DICY (Dyhard 100S, latent hardener from AlzChem for epoxy systems consisting of micronized dicyandiamide in which 98% of the particles are smaller than 10 µm.)
Dyhard UR500 Latent uron accelerator for epoxy systems with 98% of the particles smaller than 10 µm.

General description of the experiment

PD3691 and the non-nucleophilic base to be tested were mixed in a PE beaker and stored at 23° C./50% RH ([amine]o/[epoxide]o=0.1). The epoxide conversion was determined via FT-IR via the absorption signal at 914 cm ^-1 and monitored over time. Comparative examples C1-C4 show that typical non-nucleophilic bases are not suitable for catalyzing reactions in epoxides, since epoxide conversion occurs in all cases via anionic polymerization of the epoxide groups. Only when proton sponges are used, as shown in Examples B1 and B2, is there no reaction detectable in the FT-IR. m(PD3691)/g base m(base) / g Epoxy conversion after 720h / % V1 16.72 DBN 1.06 99 v2 16.01 DBU 1.25 24 V3 14.3 DIPEA 0.95 5 V4 19:31 DABCO 0.55 99 B1 16.47 DMAN 0.90 0 B2 16.52 TMGN 1.49 0

catalytic activity

Example B3 and comparative example C5 were allowed to react at RT and examples B4, B5 and comparative example C6 at 80°C. m(PD3691)/g base m(base) / g reaction partner m(reactant) / g Time to end of reaction / h B3 11:15 TMGN 0.1 butanethiol 2.57 1 V5 16:43 - - butanethiol 3.79 200 B4 9.94 DMAN 0.054 nonanoic acid 4.02 50 B5 12.67 TMGN 0.089 nonanoic acid 5:13 24 V6 24.0 - - nonanoic acid 9.72 260

The catalytic effect is graphical for B3 compared to the uncatalyzed reaction V5 in shown. The non-nucleophilic bases according to the invention are also outstandingly suitable for the epoxy-carboxylic acid reaction. B4 and B5 react much faster (50h, 24h) than the uncatalyzed reaction (260h). The non-nucleophilic bases in V1-V4 known in the prior art lead to an uncontrolled reaction, ie the epoxide conversion is too high. Surprisingly, a very special group of substances was found that on the one hand catalyzes epoxy reactions and at the same time does not start anionic polymerization.

Heat-curing adhesive

The surprisingly found effect of the proton sponges can be used in particular to produce pre-reacted adhesives which, in contrast to the prior art, can also be stored at room temperature. example B6 B7 V7 V8 weight [G] [G] [G] [G] PD3691 9.36 8.51 9.34 13.06 Hypro 1300X8 CTBN 9.43 8.43 9.38 13.75 TMGN 0.082 DMAN 0.045 DBN 0.06 DICY 0.78 0.71 0.78 1.09 UR500 0.047 0.043 0.047 0.065 Epoxy turnover at 3 months(5)RT 10% 10% 27% 7% Epoxy conversion after curing (30 min. @180°C) quantitatively quantitatively quantitatively quantitatively

The two adhesives B6 and B7 can be readily pre-reacted with the two claimed proton sponges. If, as in V7, DBN, which is familiar to the person skilled in the art, is used as a non-nucleophilic catalyst for the epoxide-carboxylic acid pre-reaction, the epoxide conversion does not stop at the 10% conversion of the epoxide groups with the carboxylic acid groups of the CTBN, but continues continuously as anionic epoxide polymerization. After 3 months of storage at RT, 27% of the epoxide groups have already reacted. Ultimately, such an unstable adhesive mass loses its "stickiness" over time due to the ongoing reaction and thus becomes unusable. Without a catalyst, the reaction proceeds too slowly (V8). After 3 months at RT, a turnover of only 7% can be measured.

Room temperature curing 2-component adhesive

20 g of a bisphenol A diglycidyl ether (Epikote 828), 5 g of a cresyl glycidyl ether reactive diluent (Araldite DY-K), 9 g glass beads, 0.4 g TMGN and 1 g Aerosil R202 were mixed in a speed mixer and yielded component A of the 2nd -Component adhesive.

25 g of Capcure 3-800 (mercaptan-terminated liquid curing agent), 3 g of glass beads and 1 g of Aerosil R202 were mixed in a speed mixer to form component B of the 2-component adhesive.

Component A was also storable after 3 months at room temperature (no increase in viscosity was observed). If components A and B are mixed in a mixing ratio of 1:1, a fast-curing adhesive is obtained.

The advantage here is the higher storage stability of the system. It is completely clear to the person skilled in the art when producing 2-component epoxy-thiol adhesives that neither the thiol nor conventional catalysts can be added to the epoxy component. Accordingly, the catalysts are usually added to the thiol and degradation is accepted. For industrial processes with high adhesive requirements, the prior art recommends adding the catalyst shortly before using the adhesive. However, if the proton sponges according to the invention are used as a catalyst, this can already be present in the epoxy part of the two-component adhesive, as shown in the example. This prevents degradation in the thiol part.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited 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.

Patent Literature Cited

• US2015232610A1 [0005]
• DE 102013222739 [0025]
• DE 102019209513 [0025]
• DE 102015225854 [0025]
• US3018262 [0028]
• WO 2019101918 A1 [0068]
• US 6838170 B2 [0068]
• US 9589693 B2 [0068]

Claims (14)

1-component epoxy-based adhesive, comprising i) at least one epoxy resin; ii) at least one proton sponge; iii) at least one compound capable of reacting with the epoxy resin; iv) optionally a film former matrix; and v) optionally at least one additive. 1-component adhesive according to claim 1 , further comprising vi) at least one hardener different from iii), vii) optionally at least one accelerator. 2-component adhesive, comprising A) a first component, which ai) at least one epoxy resin; aii) at least one proton sponge; aiii) optionally a film former matrix; and aiv) optionally comprises or consists of at least one additive and B) a second component, which bi) at least one compound capable of reacting with the epoxy resin; bii) optionally a film former matrix; and biii) optionally comprises or consists of at least one additive. 2-component adhesive according to claim 3 , characterized in that component A) exhibits essentially no epoxide polymerisation after storage at 23°C for one month. Adhesive according to one of the preceding claims, characterized in that the at least one proton sponge has the general formula (I).

where A and B together form a substituted or unsubstituted polycyclic aromatic radical; wherein R ¹ and R ² are independently selected from C _1-4 alkyl or R ¹ and R ² together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl )H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl) form; and wherein R ³ and R ⁴ are independently selected from C _1-4 alkyl or R ³ and R ⁴ together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N( alkyl)H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl ) form; or has the general formula (II).

where A and B are independently selected from substituted or unsubstituted aromatic groups, where R ¹ and R ² are independently selected from C _1-4 alkyl group or R ¹ and R ² together represent =C(alkyl) ₂ , =C( N(alkyl) ₂ ) ₂ , =C(N(alkyl)H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) form ₂ , =S(=O)(phenyl)(alkyl); wherein R ³ and R ⁴ are independently selected from C _1-4 alkyl or R ³ and R ⁴ together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl )H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl) form; and wherein Z is a heteroatom; or has the general formula (III).

wherein R ¹ and R ² are independently selected from C _1-4 alkyl. Adhesive according to one of the preceding claims, characterized in that the at least one proton sponge has the general formula (Ia).

wherein R ¹ and R ² are independently selected from C _1-4 alkyl or R ¹ and R ² together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl )H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl) form; and wherein R ³ and R ⁴ are independently selected from C _1-4 alkyl or R ³ and R ⁴ together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N( alkyl)H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl ) form; or has the general formula (IIa).

wherein R ¹ and R ² are independently selected from C _1-4 alkyl or R ¹ and R ² together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl )H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl) form; wherein R ³ and R ⁴ are independently selected from C _1-4 alkyl or R ³ and R ⁴ together represent =C(alkyl) ₂ , =C(N(alkyl) ₂ ) ₂ , =C(N(alkyl )H) ₂ , =P(N(alkyl) ₂ ) ₃ , =P(N(alkyl)H) ₃ , =S(=O)(alkyl) ₂ , =S(=O)(phenyl)(alkyl) form; and where Z is selected from N, P, S or O. Adhesive according to one of the preceding claims, characterized in that the at least one proton sponge is selected from 1,8 bis (dimethylamino) naphthalene, 1,8 bis (tetramethylguanidino) naphthalene, 1,8 bis (dimethylguanidino) naphthalene, 1, 8 bis(hexamethyliminophosphoranyl)naphthalene, 4,5-bis(dimethylamino)fluorene, 4,5-bis(dimethylamino)heterofluorene, or mixtures thereof. Adhesive according to one of the preceding claims, characterized in that the at least one proton sponge is contained in 0.001 to 5% by weight based on the total weight of the 1-component adhesive or component A of the 2-component adhesive. Adhesive according to any one of the preceding claims, characterized in that the at least one compound capable of reacting with the epoxy resin is selected from thiols, carboxylic acids or mixtures thereof. Process for producing a crosslinked adhesive by reacting component A with component B of the 2-component adhesive according to one of claims 3 until 9 . Crosslinked adhesive obtained by the method according to claim 10 . Adhesive tape containing the 1-component adhesive according to one of Claims 1 or 2 or 5 until 9 or the 2-component adhesive according to one of claims 3 until 9 or according to the crosslinked adhesive claim 11 . Pre-reacted adhesive tape according to claim 12 , contain the cross-linked adhesive according to claim 11 , characterized in that at least 5% of the original epoxy groups have pre-reacted with at least one compound capable of reacting with the epoxy resin and a maximum of 50% have been reacted, and/or the functionality of the at least one compound capable of reacting with the Epoxy resin capable is at least 2. Using a proton sponge as a catalyst to make epoxy adhesives.

Images