阅读说明：本技术 用于结构性连接具有不同线性热膨胀系数的基材的方法 (Method for structurally joining substrates having different coefficients of linear thermal expansion ) 是由 U·莱因格尔 E·詹杜比 D·加洛 C·克吕格 于 2018-12-18 设计创作，主要内容包括：本发明涉及通过使用包含基于末端封闭聚氨酯预聚物的增韧剂的单组分热固化环氧树脂组合物连接具有不同热膨胀系数的基材的方法,特别是在交通工具或家用电器的壳体构造中。(The invention relates to a method for joining substrates having different coefficients of thermal expansion, in particular in the construction of housings for vehicles or domestic appliances, by using a one-component heat-curable epoxy resin composition comprising a flexibilizer based on a blocked polyurethane prepolymer.)

1. A method for bonding thermally stable substrates comprising the steps of:

i) applying a one-component heat-curable epoxy resin composition on the surface of a heat-stable substrate S1, in particular a metal;

ii) bringing the applied thermosetting epoxy resin composition into contact with a surface of another heat-stable substrate S2, in particular a metal, wherein the thickness of the applied thermosetting epoxy resin composition after step ii) is ≥ 0.8mm, in particular ≥ 1 mm;

iii) heating the composition to a temperature of 100-;

wherein the one-component thermosetting epoxy resin composition comprises:

a) at least one epoxy resin a having an average of more than one epoxy group per molecule;

b) at least one latent curing agent B for epoxy resins;

wherein the weight ratio of the at least one epoxy resin A having an average of more than one epoxy group per molecule to the at least one flexibilizer D is from 0.3 to 2.2,

and wherein the toughening agent D is a terminally blocked polyurethane prepolymer of formula (I);

wherein R is¹Represents the p-valent groups of the isocyanate group-terminated linear or branched polyurethane prepolymers after removal of the terminal isocyanate groups;

p represents a value of 2 to 8; and is

R²Represents a terminal blocking group which decomposes at a temperature above 100 ℃ wherein R²Do not represent a substituent selected from

Wherein

R¹²Represents an alkylene group having 2 to 5 carbon atoms and optionally having a double bond or being substituted, or represents a phenylene group or a hydrogenated phenylene group, in particular-caprolactam after removal of the NH-proton; and is

R¹⁹Denotes bisphenols after removal of one hydroxyl group, in particular bisphenol-A, bisphenol-F and 2, 2' -diallylbisphenol-A, and

wherein the one-component heat-curable epoxy resin composition has a maximum linear expansion ≧ Max. expansion ≧ 1.65mm which is determined in a tensile shear test during cooling of the heated and cured tensile shear specimen, and

wherein the tensile shear test is carried out at a tensile speed V of 0.40mm/min_ZugThe maximum linear expansion "Max. expansion" is measured, and

wherein the temperature of the tensile shear sample of the tensile shear test at the beginning of the measurement is 180 ℃, in particular 190 ℃, and the tensile shear sample is cooled to a temperature of 25 ℃ at the beginning of the measurement at a cooling rate of 40 ℃/min and then kept at this temperature.

2. The method of claim 1, wherein

R²Independently represent a substituent selected from

Wherein

R⁵、R⁶、R⁷And R⁸Each independently of the others, represents alkyl or cycloalkyl or aralkyl or arylalkylBase of

Or R⁵Together with R⁶Or R⁷Together with R⁸Forming a part of an optionally substituted 4-to 7-membered ring;

R⁹、R^9’and R¹⁰Each independently of the others represents alkyl or aralkyl or arylalkyl or alkoxy or aryloxy or aralkyloxy;

R¹¹represents an alkyl group, and is represented by,

R¹³and R¹⁴Each independently of the other represents an optionally double-bonded or substituted alkylene group having 2 to 5 carbon atoms, or represents a phenylene group or a hydrogenated phenylene group;

R¹⁵、R¹⁶and R¹⁷Each independently of the others represents H or an alkyl or aryl or aralkyl group; and is

R¹⁸Represents an aralkyl group or a substituted or unsubstituted mononuclear or polynuclear aromatic group optionally having an aromatic hydroxyl group;

R⁴denotes the radical of an aliphatic, cycloaliphatic, aromatic or araliphatic epoxide containing primary or secondary hydroxyl groups after removal of the hydroxyl and epoxide groups;

and m represents a value of 1, 2 or 3.

3. The method of claim 1 or 2, wherein

R²Independently represent a substituent selected from

Wherein

R⁵、R⁶、R⁷And R⁸Each independently of the others, represents alkyl or cycloalkyl or aralkyl or arylalkyl

Or R⁵Together with R⁶Or R⁷Together with R⁸Forming a part of an optionally substituted 4-to 7-membered ring;

R¹⁵、R¹⁶and R¹⁷Each independently of the other represents H or an alkaneAryl or aralkyl; and is

R¹⁸Represents an aralkyl group or a substituted or unsubstituted mononuclear or polynuclear aromatic group optionally having an aromatic hydroxyl group,

preferably, R²Is selected from

In particular, R²Is selected from

Particularly preferably, R²Is selected from

Most preferably, R²Is- - - -O- -R¹⁸。

4. The process according to any of the preceding claims, wherein the weight ratio of the at least one epoxy resin a having an average of more than one epoxy group per molecule to the at least one flexibilizer D is from 0.4 to 2.0, particularly preferably from 0.5 to 1.8.

5. The method of any one of the preceding claims, wherein R¹Denotes the p-valent radical of a linear or branched polyurethane prepolymer which is blocked by isocyanate groups and which, after removal of the terminal isocyanate groups, is composed of at least one diisocyanate or triisocyanate and a polymer Q having terminal amino, mercapto or hydroxyl groups_PMAnd (4) preparing.

6. The method of claim 5, wherein the polymer Q has a terminal amino, thiol, or hydroxyl group_PMIs a polyol having an average molecular weight of between 600 and 6000 daltons, said polyol being selected from the group consisting of polyethylene glycol, polypropylene glycol, polyethylene glycolAlcohol-polypropylene glycol block polymers, polytetramethylene glycol, polytetramethylene ether glycol, hydroxyl-terminated polybutadiene, hydroxyl-terminated butadiene-acrylonitrile copolymers and mixtures thereof, with polytetramethylene ether glycol and hydroxyl-terminated polybutadiene being particularly preferred.

7. The method of claim 6, wherein the polymer Q has a terminal amino, thiol, or hydroxyl group_PMIs a polyol having an average molecular weight of between 600 and 6000 daltons, selected from polytetramethylene ether glycol and hydroxyl-terminated polybutadiene, wherein the weight ratio of polytetramethylene ether glycol to hydroxyl-terminated polybutadiene is from 100/0 to 70/30, preferably from 100/0 to 60/40, preferably from 100/0 to 90/10, very particularly preferably 100/0.

8. The process according to any of the preceding claims, wherein the applied heat-curable epoxy resin composition has a thickness after step ii) of ≥ 1.0mm, in particular ≥ 1.2mm, preferably ≥ 1.5 mm.

9. The method according to any of the preceding claims, wherein the drawing speed V in the tensile shear test is at 0.40mm/min, in particular 0.52mm/min, preferably 0.68mm/min_ZugThe maximum linear expansion "max. expansion" is measured below.

10. The process according to any of the preceding claims, wherein in step iii) the composition is heated to a temperature of 100-.

11. The method according to any one of the preceding claims, wherein the tensile shear test is a tensile shear test using a tensile shear specimen having the following characteristics:

-a steel plate with dimensions 25mm x 100mm x 1.5mm,

an adhesive face of the cured one-component heat-curable epoxy resin composition having dimensions 10mm x 25mm and a thickness of 1.5mm, preferably 1.0 mm.

12. The process according to any one of the preceding claims, wherein the maximum linear expansion "Max. expansion" is ≥ 1.8mm, preferably ≥ 2.0mm, preferably ≥ 2.145mm, preferably ≥ 2.2mm, preferably ≥ 2.5mm, preferably ≥ 2.8mm, preferably ≥ 3.0mm, preferably ≥ 3.5mm, preferably ≥ 4.0 mm.

13. The method according to any of the preceding claims, wherein the maximum force measured is 6000N or less, preferably 5000N or less, preferably 4500N or less, preferably 4000N or less, preferably 3500N or less, preferably 3000N or less, preferably 2500N or less, preferably 2000N or less.

14. The method according to any one of the preceding claims, wherein the force measured at the time of reaching a maximum linear expansion "Max. expansion" of ≥ 1.8mm, preferably ≥ 2.0mm, preferably 2.145mm ≤ 4000N, preferably ≤ 3000N, preferably ≤ 2500N, preferably ≤ 2000N, preferably ≤ 1500N, preferably ≤ 1000N, preferably ≤ 800N, preferably ≤ 700N.

15. The method of any preceding claim, wherein the method is a method for vehicle construction and sandwich panel construction.

Technical Field

The present invention relates to the field of heat-curable epoxy resin compositions, in particular for joining substrates having different coefficients of thermal expansion, in particular in the construction of housings for vehicles or domestic appliances.

Background

Thermally curable epoxy resin compositions have been known for a long time. An important field of application for heat-curable epoxy resin compositions is vehicle construction, in particular in the bonding in the housing construction of vehicles or domestic appliances. In both cases, the bonded article is heated in an oven after the application of the epoxy resin composition, whereby the heat-curing epoxy resin composition is also cured.

If two substrates with different coefficients of linear thermal expansion are connected to each other by a structural connection, performing the curing step in an oven at a temperature of 120-220 ℃ will cause the two substrates to expand to different lengths. On subsequent cooling, high stresses can therefore occur in the cured epoxy resin composition, which lead either to failure of the adhesive bond, deformation of the substrate or to so-called "freezing" of stresses in the adhesive bond. As a result of this "freezing", the adhesive connection is significantly more sensitive to static, dynamic and impact loads over its lifetime, which may lead to a weakening of the adhesive connection.

There is therefore a need for a process for the structural connection of substrates having different coefficients of linear thermal expansion by means of thermosetting epoxy resin compositions, which process ensures, on the one hand, sufficient mechanical properties for the structural connection and, on the other hand, enables the connection body to withstand the high stresses occurring on thermal curing and the structural connection does not fail.

Disclosure of Invention

It is therefore an object of the present invention to provide a process for the structural connection of substrates having different coefficients of linear thermal expansion by means of a heat-curing epoxy resin composition, which process ensures, on the one hand, sufficient mechanical properties for the structural connection and, on the other hand, enables the connection body to withstand the high stresses occurring during thermal curing and the structural connection does not fail.

Surprisingly, this object is achieved by the process according to the invention as claimed in claim 1.

Other aspects of the invention are the subject of other independent claims. Particularly preferred embodiments of the invention are the subject matter of the dependent claims.

Detailed Description

The invention relates to a method for bonding thermally stable substrates, comprising the following steps:

i) applying a one-component heat-curable epoxy resin composition on the surface of a heat-stable substrate S1 (in particular a metal);

ii) contacting the applied thermosetting epoxy resin composition with a surface of a further heat stable substrate S2, in particular a metal, wherein the thickness of the applied thermosetting epoxy resin composition after step ii) is ≥ 0.8mm, in particular ≥ 1mm,

iii) heating the composition to a temperature of 100-220 ℃, especially 120-200 ℃, preferably between 130 and 150 ℃, particularly preferably between 130 and 140 ℃.

The one-component thermosetting epoxy resin composition comprises:

a) at least one epoxy resin a having an average of more than one epoxy group per molecule;

b) at least one latent curing agent B for epoxy resins;

wherein the weight ratio of the at least one epoxy resin A having an average of more than one epoxy group per molecule to the at least one toughening agent D is from 0.3 to 2.2, and wherein the toughening agent D is a terminally blocked polyurethane prepolymer of formula (I);

wherein R is¹Represents the p-valent groups of a linear or branched polyurethane prepolymer blocked by isocyanate groups after removal of the terminal isocyanate groups;

p represents a value of 2 to 8; and is

R²Represents a blocking group which decomposes at a temperature above 100 ℃ wherein R²Do not represent a substituent selected from

Wherein

R¹²Represents an alkylene group having 2 to 5 carbon atoms and optionally having a double bond or being substituted, or represents a phenylene group or a hydrogenated phenylene group, in particular a group of caprolactam after removal of NH-protons; and is

R¹⁹Refers to bisphenols after removal of one hydroxyl group, particularly bisphenol-A, bisphenol-F and 2, 2' -diallylbisphenol-A.

The one-component thermosetting epoxy resin composition has a maximum linear expansion ≧ Max. expansion ≧ 1.65mm which is determined in a tensile shear test during cooling of the heated and cured tensile shear sample.

In a tensile shear test at a tensile speed V of 0.40mm/min_ZugThe maximum linear expansion "max. expansion" was measured.

The temperature of the tensile shear sample of the tensile shear test at the beginning of the measurement is 180 ℃, in particular 190 ℃, and the tensile shear sample is cooled to a temperature of 25 ℃ at the beginning of the measurement at a cooling rate of 40 ℃/min and then kept at this temperature.

Herein, the expression "independently of each other" is used with respect to a substituent, group or group to denote: substituents, groups or radicals which are labeled in the same way in the same molecule may occur simultaneously in different meanings.

"toughener" is understood herein to mean an additive to the epoxy resin matrix which, at low addition levels of 5% by weight or more, in particular 10% by weight or more, based on the total weight of the epoxy resin composition, leads to a significant increase in toughness and thus to the ability to absorb higher bending, tensile, impact or crash loads before the matrix tears or breaks.

The prefix "poly" in the names of substances (e.g., "polyol", "polyisocyanate", "polyether" or "polyamine") indicates herein that each substance formally contains more than one functional group per molecule present in its name.

"molecular weight" is understood herein to mean the molar mass of a molecule (in g/mol). "average molecular weight" means the number average molecular weight M of a mixture of molecules in oligomeric or polymeric form_nIt is usually determined by GPC against polystyrene standards.

"primary hydroxyl" means an OH-group bonded to a carbon atom having two hydrogens.

The term "primary amino group" denotes herein NH bound to one organic group₂-groups, whereas the term "secondary amino" denotes NH-groups bound to two organic groups (which may also be common parts of the ring). Thus, amines having primary amino groups are referred to as "primary amines", amines having secondary amino groups are referred to as "secondary amines", and amines having tertiary amino groups are referred to as "tertiary amines".

"room temperature" herein means a temperature of 23 ℃.

Description of the method for measuring maximum linear expansion ("Max. expansion") and maximum force

If two substrates (e.g., metal or fiber-reinforced plastic) having different coefficients of linear thermal expansion (Δ α) are joined to one another by a structural bond (particularly in vehicle body construction), the curing step carried out in an oven at temperatures of 120-.

To enable better study of the properties of the cured epoxy resin compositions, a laboratory method for evaluating the resistance of the compositions to "Δ α -induced" stress was developed.

In the laboratory method, stress is not induced by linear thermal expansion (which would otherwise require a specimen having dimensions similar to a real vehicle body part), but rather "Δ α stress" is applied to the tensile shear specimen by a tensile tester.

Samples used and preparation thereof

To simulate the "Δ α -induced" stress, tensile shear specimens made of galvanized steel sheet (thickness 1.5mm, yield limit 420MPa) were used in the following manner:

preparation:

1.) cleaning the steel plates (25mm x 100mm x 1.5mm) with heptane and then with 3g/m²AntiticoritP L3802-39S (FuCHS Schmierstuffe GmbH) in the specified manner.

2.) defining a bonding surface (10mm x 25mm) with a teflon spacer (thickness 0.5mm, 1.0mm or 1.5mm) and applying the epoxy resin composition.

3.) joining the steel plates and fixing the sides of the adhesive faces with clips, respectively.

4.) the tensile shear sample was adjusted at 180 ℃ for 35min (residence time) to cure the epoxy resin composition.

5.) remove the Teflon pad after cooling the sample.

Determination of parameters

As already mentioned, this test method is generally applicableThe speed of the tensile shear samples was set to simulate various Δ α induced stress conditions, hereafter in aluminum-clad steel (Δ α ═ 13 × 10)^-6K^-1) The material combination of the composition is taken as an example, and the necessary drawing speed is calculated in consideration of equations (1) and (2).

Linear approximation of solid thermal expansion

Equation (1) Δ L ═ L₀*α*ΔT

Equation (1) Δ T ═ T₂-T₁

Initial length L of two engaged objects₀Is 1000 mm. The temperature profile shown in fig. 1 is defined for heating and cooling of the sample according to the temperature profile common in convection boxes. Thus giving the starting and final temperatures T₁/T₂And a temperature difference Δ T. The heating rate and cooling rate are likewise selected to be 40 ℃/min, which is customary in the automotive industry.

L₀＝1000mm

α_Stahl＝10.8*10^-6[K^-1]

α_Alu＝23.8*10^-6[K^-1]

ΔT＝165[K]

T₂＝190[℃]

T₁＝25[℃]

Equation (4)

ΔL_Stahl＝1000mm*10.8*10^-6K^-1*165K＝1.782mm

Equation (5)

ΔL_Alu＝1000mm*23.8*10^-6K^-1*165K＝3.927mm

Coefficient of thermal expansion α of steel_StahlAnd coefficient of thermal expansion α of aluminum_AluIf defined values are inserted in equations 1 and 2, the thermal expansion Δ L of steel and aluminum is obtained according to equations 4 and 5, this results in a difference in linear expansion of 2.145mm during the heating phase, making the aluminum expand more significantly than the steel, accordingly, the cured epoxy resin composition forming the cohesive connection must compensate for the difference in shrinkage also of 2.145mm during the cooling phase, taking into account a cooling rate V of 40 ℃/min_AAnd thus according to equations 6 and 7A drawing speed V of 0.52mm/min_Zug。

Equation (6)

Equation (7)

The measurement was carried out:

1.) tensile shear samples prepared according to the above preparation instructions were tensioned in a tensile tester. But only the lower jaw is fixed first. The tensioning length is 100 mm.

2.) two thermocouples were pressed onto the sample in contact with the adhesive surface.

3.) the starting and final temperatures are set to 25 ℃ and 180 ℃, in particular 190 ℃, on the control unit. The heating rate and cooling rate were input at 40 deg.C/min.

4.) the heating phase starts.

5.) when a final temperature of 180 ℃, in particular 190 ℃, is reached, it is kept for 2 minutes by a countdown to ensure uniform heating of the adhesive face.

6.) 30 seconds before the end of the countdown, at which time the tensile sheared sample is also held by the upper jaw.

7.) the cooling phase starts automatically as the countdown ends. At the same time, a tensile shear test at a tensile speed of 0.52mm/min was started manually by the control software of the tensile tester.

Measurement results and evaluation

The measurement result is the force required to deform the tensile shear specimen during cooling from 180 c, in particular 190 c, to 25 c until breaking. Three measurements were made for each epoxy resin composition. Linear expansion "max. expansion" is determined from the traversed distance traversed. For evaluating the measurement, the maximum force (. sigma.) is obtained from the measurement record_M2) Maximum linear expansion of "max. expansion" ((iii))_M2) Average value of (a).

Herein, the higher the maximum linear expansion "max. expansion" reached, the more "Δ α tolerant" the epoxy resin composition can be considered, furthermore, when a small maximum force has to be used, this is advantageous for an "Δ α tolerant" epoxy resin composition.

Another concern is the point in time of failure. If the point of failure time is passed before the end of the cooling phase, i.e.at a drawing speed V of 0.40mm/min_ZugThe breaking occurs before a linear expansion of 1.65mm is reached, or at a drawing speed V of 0.52mm/min_ZugConversely, if fracture occurs at an expansion of ≧ 1.65mm or ≧ 2.145mm, it is considered preferable "Δ α resistance". the higher the linear expansion, the better the "Δ α resistance".

Another parameter of interest is the force level at the end of the cooling phase (i.e. when a linear expansion of 1.65mm or 2.145mm is reached). The higher the force level here, the more freezing stress and irreversible deformation of the base material in the epoxy resin composition are expected. Accordingly, a force level as low as possible here is an advantageous result.

The maximum linear expansion "max. expansion" was determined during cooling of the heated and cured tensile shear sample in a tensile shear test.

Preferably, the tensile speed V is 0.52mm/min (preferably 0.68mm/min) in the tensile shear test_ZugThe maximum linear expansion "max. expansion" was measured.

Preferably, the determined maximum linear expansion "max. expansion" is the linear expansion at the maximum force (maximum force) measured in the tensile shear test.

Preferably, the maximum linear expansion "max. expansion" in the tensile shear test is determined from the traversed distance.

Preferably, the temperature of the tensile shear sample of the tensile shear test at the beginning of the measurement is 180 ℃, in particular 190 ℃, and the tensile shear sample is cooled to a temperature of 25 ℃ at the beginning of the measurement at a cooling rate of 40 ℃/min and then kept at this temperature. Preferably, the tensile shear sample is heated to a temperature of 180 ℃, in particular 190 ℃, with a heating rate of 40 ℃/min before starting the measurement.

Preferably, the tensile shear test is a tensile shear test to determine tensile shear strength according to DIN EN 1465.

Preferably, the tensile shear test is a tensile shear test using a tensile shear specimen having the following characteristics:

-a steel plate with dimensions 25mm x 100mm x 1.5mm,

-an adhesive surface of the cured one-component heat-curable epoxy resin composition having dimensions 10mm x 25mm and a thickness of 1.5mm, preferably 1.0 mm.

The steel sheet used is preferably made of hot-dip galvanized steel. The material also preferably has a yield limit of at least 420MPa, so that the influence of substrate deformation is kept as small as possible.

The maximum linear expansion "max. expansion" is preferably determined from the traversed distance traversed.

Preferably, the steel plate is cleaned with heptane before applying the one-component heat-curable epoxy resin composition and then at 3g/m²Oiling in a defined manner with deep-drawing oil (in particular Anticalorit P L3802-39S).

Preferably, the one-component heat-curable epoxy resin composition is cured at 180 ℃ for 35 minutes.

The thickness of the applied thermosetting epoxy resin composition after step ii) is ≧ 0.8 mm.

Preferably, the thickness is ≥ 1mm, ≥ 1.2mm, preferably ≥ 1.5mm, particularly preferably 1.5-2.5 mm.

The thickness preferably corresponds to the average distance of the two thermally stable substrates S1 and S2 in the contact area with the thermally curable epoxy resin composition.

If the thickness is less than 0.8mm, an insufficient maximum linear expansion value is obtained. For example, as can be seen in Table 10, when the thickness is 0.5mmAt a drawing speed V of 0.52mm/min_ZugExtremely low maximum linear expansion values are obtained. This can be seen, for example, in the comparison of a test specimen having a thickness of 0.5mm with a test specimen having a thickness of 1mm or 1.5 mm.

It can furthermore be seen from Table 9 that, when the weight ratio of the at least one epoxy resin A having on average more than one epoxy group per molecule to the at least one flexibilizer D is greater than 2.2, a drawing speed V of 0.52mm/min is achieved_ZugLower maximum linear expansion values are obtained.

If the drawing speed V is_Zug0.68mm/min, the weight ratio of the at least one epoxy resin A having on average more than one epoxy group per molecule to the at least one flexibilizer D must be from 0.3 to 0.6 in order to achieve a maximum linear expansion "Max. expansion" value of ≥ 2.8 mm.

Preferably, the maximum linear expansion "Max. expansion" is ≥ 1.8mm, preferably ≥ 2.0mm, ≥ 2.145mm, preferably ≥ 2.2mm, preferably ≥ 2.5mm, preferably ≥ 2.8mm, preferably ≥ 3.0mm, preferably ≥ 3.5mm, preferably ≥ 4.0 mm.

Preferably, the maximum force measured is 6000N or less, preferably 5000N or less, preferably 4500N or less, preferably 4000N or less, preferably 3500N or less, preferably 3000N or less, preferably 2500N or less, preferably 2000N or less.

Preferably, the force measured to reach a maximum linear expansion "Max. expansion" of ≥ 1.8mm, preferably ≥ 2.0mm, preferably 2.145mm ≤ 4000N, preferably ≤ 3000N, preferably ≤ 2500N, preferably ≤ 2000N, preferably ≤ 1500N, preferably ≤ 1000N, preferably ≤ 800N, preferably ≤ 700N.

A heat stable material S1 or S2 is understood to be a material which is form stable at least during the curing time at a curing temperature of 100-. These are in particular metals and plastics such as ABS, polyamides, epoxy resins, polyether resins, polyphenylene ethers, fibre-reinforced plastics such as glass-fibre-reinforced plastics and carbon-fibre-reinforced plastics. Particularly preferred as plastic is a fiber reinforced plastic. Preferably at least one of the materials is a metal.

Particularly preferred methods are bonding thermally stable substrates, particularly metals, having different coefficients of linear thermal expansion (Δ α), and/or bonding metals to fiber reinforced plastics, particularly in the body construction of the automotive industry preferred metals are mainly steels, particularly electrogalvanized, galvanealed, oiled, bonaj-coated, and subsequently phosphated steels, as well as aluminum, particularly in the variant forms commonly found in automotive manufacturing.

It is particularly preferred that the difference in the coefficient of linear thermal expansion (Δ α) between the thermal stabilizing material S1 and the thermal stabilizing material S2 is 10 to 25^*10^-6[K^-1]In particular 10-15^*10^-6[K^-1]。

Preferably, in step iii) the composition is heated to a temperature of 100-.

The epoxy resin a having an average of more than one epoxy group per molecule is preferably a liquid epoxy resin or a solid epoxy resin. The term "solid epoxy resin" is well known to those skilled in the art of epoxies and is used in contrast to "liquid epoxy resins". The glass transition temperature of the solid resin is above room temperature, i.e. it can be comminuted at room temperature to a free-flowing powder.

Preferably, the epoxy resin has the formula (II)

The substituents R 'and R' here denote, independently of one another, H or CH₃。

For solid epoxy resins, the index s represents a value >1.5, in particular 2 to 12.

Such solid epoxy resins are commercially available, for example, from Dow or Huntsman or Hexion.

Compounds of formula (II) having an index s between 1 and 1.5 are known to those skilled in the art as semi-solid epoxy resins. The semi-solid epoxy resin is also considered a solid resin for the purposes of the present invention. However, solid epoxy resins in the narrow sense, i.e. with an index s having a value >1.5, are preferred.

For liquid epoxy resins, the index s represents a value less than 1. s preferably represents a value of less than 0.2.

Thus, it is preferably diglycidyl ethers of bisphenol-A (DGEBA), bisphenol-F and bisphenol-A/F. The liquid resin may, for example, beGY 250、PY 304、GY 282(Huntsman) or d.e.r.^TM331 or d.e.r.^TM330(Dow) or Epikote 828 (Hexion).

Also suitable as epoxy resins A are the so-called epoxide novolaks. It has in particular the formula:

wherein R2 ═Or CH₂R1 ═ H or methyl and z ═ 0 to 7.

In particular, it is phenol-epoxide-novolak or cresol-epoxide-novolak (R2 ═ CH)₂)。

The epoxy resin is under the trade name EPN or ECN andcommercially available from Huntsman or as product series d.e.n.^TMCommercially available from Dow Chemical.

Epoxy resin a preferably represents a liquid epoxy resin of formula (II).

In a particularly preferred embodiment, the thermally curable epoxy resin composition comprises not only at least one liquid epoxy resin of the formula (II) in which s <1, in particular less than 0.2, but also at least one solid epoxy resin of the formula (II) in which s >1.5, in particular from 2 to 12.

Preferably, the proportion of epoxy resin A is from 10 to 60% by weight, in particular from 30 to 50% by weight, based on the total weight of the epoxy resin composition.

It is also advantageous if 60 to 100% by weight, in particular 60 to 80% by weight, of the epoxy resin A is the abovementioned liquid epoxy resin.

It is also advantageous if from 0 to 40% by weight, in particular from 20 to 40% by weight, of the epoxy resin A is the abovementioned solid epoxy resin.

The heat-curable epoxy resin composition comprises at least one latent curing agent B for epoxy resins. The latent curing agent B is activated by an elevated temperature, preferably a temperature of 70 ℃ or higher.

The curing agent B is preferably a curing agent selected from dicyandiamide, guanidine, anhydrides of polycarboxylic acids, dihydrazide and aminoguanidine.

A particularly preferred curing agent B is dicyandiamide.

The amount of latent curing agent B is advantageously from 0.1 to 30% by weight, in particular from 0.2 to 10% by weight, preferably from 1 to 10% by weight, particularly preferably from 5 to 10% by weight, based on the weight of the epoxy resin A.

Preferably, the heat-curable epoxy resin composition further comprises at least one accelerator C for epoxy resins. Such accelerating curing agents are preferably substituted ureas, such as 3- (3-chloro-4-methylphenyl) -1, 1-dimethylurea (chlorotoluron) or phenyl-dimethylurea, especially p-chlorophenyl-N, N-dimethylurea (mesosulfuron), 3-phenyl-1, 1-dimethylurea (fenuron) or 3, 4-dichlorophenyl-N, N-dimethylurea (diuron). Imidazoles such as 2-isopropylimidazole or 2-hydroxy-N- (2- (2- (2-hydroxyphenyl) -4, 5-dihydroimidazol-1-yl) ethyl) benzamide, imidazoline, and amine complexes may also be used.

Preferably, the accelerator C for epoxy resins is selected from the group consisting of substituted ureas, imidazoles, imidazolines, and amine complexes.

Particularly preferably, the accelerator C for epoxy resins is selected from substituted ureas and amine complexes, especially when the latent hardener B is a guanidine (especially dicyandiamide).

The one-component thermosetting epoxy resin composition comprises at least one toughening agent D. The toughening agent D may be a solid or a liquid.

The toughening agent D is a polyurethane polymer with a closed end and a formula (I).

Where R is¹Denotes a p-valent group of a linear or branched polyurethane prepolymer terminated with isocyanate groups after removal of terminal isocyanate groups, and p denotes a value of 2 to 8.

Furthermore, R²Represents a blocking group which decomposes at a temperature above 100 ℃ wherein R²Do not represent a substituent selected from

Wherein

R¹²Represents an alkylene group having 2 to 5 carbon atoms and optionally having a double bond or being substituted, or represents a phenylene group or a hydrogenated phenylene group, in particular a group of caprolactam after removal of NH-protons; and is

R¹⁹Denotes the radical of a bisphenol after removal of one hydroxyl group, in particular of bisphenol-A, bisphenol-F and 2, 2' -diallylbisphenol-A, particular preference being given to bisphenol-A and bisphenol-F. In the present context, the term "bisphenol" is preferably understood to mean a compound which contains as a common structural feature two benzene rings connected by carbon atoms.

It has surprisingly been found that by means of the abovementioned substituents

The maximum linear expansion "max. expansion" obtained is insufficient. This can be seen, for example, in the comparison of examples 8 and 9 of table 4 with the examples of table 3.

Preferably, R²Independently of one another, represent a group selected fromSubstituent(s) of

Wherein

R⁵、R⁶、R⁷And R⁸Each independently of the others, represents alkyl or cycloalkyl or aralkyl or arylalkyl

Or R⁵Together with R⁶Or R⁷Together with R⁸Forming a part of an optionally substituted 4-to 7-membered ring;

R⁹、R^9’and R¹⁰Each independently of the others represents alkyl or aralkyl or arylalkyl or alkoxy or aryloxy or aralkyloxy;

R¹¹represents an alkyl group, and is represented by,

R¹³and R¹⁴Each independently of the other represents an optionally double-bonded or substituted alkylene group having 2 to 5 carbon atoms, or represents a phenylene group or a hydrogenated phenylene group;

R¹⁵、R¹⁶and R¹⁷Each independently represents H or an alkyl or aryl or aralkyl group; and is

R¹⁸Represents an aralkyl group having a substituted or unsubstituted aromatic group or a substituted or unsubstituted mononuclear aromatic group optionally having an aromatic hydroxyl group;

R⁴denotes the radical of an aliphatic, cycloaliphatic, aromatic or araliphatic epoxide containing a primary or secondary hydroxyl group after removal of the hydroxyl and epoxide groups;

and m represents a value of 1, 2 or 3.

Particularly preferably, R²Independently represent a substituent selected from

In particular

Preference is given to

Is particularly preferred

Most preferably

It has been surprisingly found that higher values of modulus of elasticity, tensile strength, elongation at break, tensile shear strength, angle peel strength and impact peel strength are thereby obtained. This can be seen, for example, in a comparison of examples 1 to 7 of Table 3.

As R¹⁸In particular, groups of phenol after removal of one hydroxyl group are considered. Preferred examples of such phenols are in particular selected from phenol, cresol, 4-methoxyphenol (hqme), resorcinol, catechol, cardanol (3-pentadecanylphenol (from cashew nut shell oil)) and nonylphenol.

As R¹⁸On the other hand, the groups of hydroxybenzyl alcohol and benzyl alcohol after removal of one hydroxyl group are particularly considered.

Preferably as the formula- - - -O- -R¹⁸The substituent(s) is a group of the monophenol after removal of one phenol hydrogen atom. Such a radical R²Are selected from the group consisting of

Preference is given to

The radical Y here denotes a groupSaturated aromatic or olefinically unsaturated hydrocarbon radicals having from 1 to 20 carbon atoms, in particular from 1 to 15 carbon atoms. Particularly preferred as Y are allyl, methyl, nonyl, dodecyl, phenyl, alkyl ethers (in particular methyl ether), carboxylic esters or unsaturated C's having 1 to 3 double bonds₁₅-an alkyl group. Y is most preferably selected from alkyl ethers (in particular methyl ether) and unsaturated C having 1 to 3 double bonds₁₅-an alkyl group.

Particularly preferably, R¹⁸Particularly preferred examples of such phenols are selected from 4-methoxyphenol (HQMME) and cardanol (3-pentadecenylphenol (from cashew nut shell oil)) for the group of phenol after removal of one hydroxyl group.

When R is⁵、R⁶、R⁷、R⁸、R⁹、R^9’、R¹⁰、R¹¹、R¹⁵、R¹⁶Or R¹⁷When it represents an alkyl group, it is in particular a linear or branched C₁-C₂₀-an alkyl group.

When R is⁵、R⁶、R⁷、R⁸、R⁹、R^9’、R¹⁰、R¹⁵、R¹⁶Or R¹⁷When an aralkyl group is represented, the group is in particular an aromatic group bound via a methylene group, in particular a benzyl group.

When R is⁵、R⁶、R⁷、R⁸、R⁹、R^9’Or R¹⁰When it represents an alkylaryl group, it is especially C bound via a phenylene radical₁-to C₂₀Alkyl groups, such as tolyl or xylyl.

Linear or branched polyurethane prepolymers blocked by isocyanate groups and one or more isocyanate-reactive compounds R²H to prepare a terminally blocked polyurethane prepolymer of formula (I). If a plurality of said isocyanate-reactive compounds is used, the reaction can be carried out in succession or with mixtures of compounds.

Polyurethane prepolymers (R) having terminal isocyanate groups¹Based thereon) can be prepared from at least one diisocyanate or triisocyanate and from compounds having terminal amino groups, mercapto groupsPolymers Q of radicals or hydroxy groups_PMAnd (4) preparing.

Suitable diisocyanates are aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, in particular the commercial products such as methylene diphenyl diisocyanate (MDI), Hexamethylene Diisocyanate (HDI), Toluene Diisocyanate (TDI), tolidine diisocyanate (TODI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), 2, 5-or 2, 6-bis- (isocyanatomethyl) -bicyclo [2.2.1]Heptane, 1, 5-Naphthalene Diisocyanate (NDI), dicyclohexyl methyl diisocyanate (H)₁₂MDI), p-phenylene diisocyanate (PPDI), m-tetramethylxylylene diisocyanate (TMXDI), etc., and dimers thereof. HDI, IPDI, MDI or TDI are preferred.

Suitable triisocyanates are trimers or biurets of aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, in particular isocyanurates and biurets of the diisocyanates mentioned in the preceding paragraph. It is of course also possible to use suitable mixtures of diisocyanates or triisocyanates.

Particularly suitable as polymers Q having terminal amino, mercapto or hydroxyl groups_PMOf polymers Q having two or three terminal amino, mercapto or hydroxyl groups_PM。

Polymer Q_PMAdvantageously having an equivalent weight of 300-6000, in particular 600-4000, preferably 700-2200 g/equivalent of NCO-reactive groups.

Preferred as polymers Q_PMSelected from the group consisting of polyols having an average molecular weight between 600 and 6000 daltons: polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol block polymers, polytetramethylene glycol, polytetramethylene ether glycol, hydroxyl-terminated polybutadiene, hydroxyl-terminated butadiene-acrylonitrile copolymers and mixtures thereof, polytetramethylene ether glycol and hydroxyl-terminated polybutadiene being particularly preferred.

One or more polytetramethylene ether glycols may be used. Polytetramethylene ether glycol is also known as polytetrahydrofuran or PTMEG. PTMEG may be prepared, for example, by polymerization of tetrahydrofuran (e.g., by an acidic catalyst). Polytetramethylene ether glycols are in particular diols.

Polytetramethylene ether glycols are commercially available, e.g. from BASFProducts, e.g.2000、2500CO or3000CO, Invista B.VProducts or L yondell BasellAnd (5) producing the product.

The OH-functionality of the polytetramethylene ether glycol used is preferably in the range of about 2, for example in the range of 1.9 to 2.1. This is obtained by cationic polymerization of the starting monomer tetrahydrofuran.

Advantageously, the polytetramethylene ether glycol has an OH value of between 170 and 35mg KOH/g, preferably in the range from 100 to 40mg KOH/g, very particularly preferably in the range from 70 to 50mg KOH/g. The OH value is determined titratively in accordance with DIN 53240 in the present application, if not stated otherwise.

The hydroxyl number is determined here by acetylation with acetic anhydride and then titration of the excess acetic anhydride with alcoholic potassium hydroxide. The OH equivalent or the average molecular weight of the polytetramethylene ether glycol used can be determined by titration of the calculated hydroxyl number, knowing the bifunctionality.

Advantageously, the polytetramethylene ether glycol used in the invention preferably has an average molecular weight in the range from 600 to 5000g/mol, more preferably from 1000 to 3000g/mol, particularly preferably from 1500 to 2500g/mol, in particular an average molecular weight of about 2000 g/mol.

One or more hydroxyl-terminated polybutadienes may be used. Mixtures of two or more hydroxyl-terminated polybutadienes may also be used.

Suitable hydroxyl-terminated polybutadienes are in particular those prepared by free-radical polymerization of 1, 3-butadiene, using, for example, azonitrile or hydrogen peroxide as initiator. Hydroxyl-terminated polybutadiene is commercially available, for example, Poly from Cray ValleyProduct (Poly)R45V), from EvonikHT and from Emerald Performance Materials LL C2800X95HTB。

The hydroxyl-terminated polybutadiene preferably has an average molecular weight of less than 5000, preferably from 2000 to 4000 g/mol. The OH functionality of the hydroxyl-terminated polybutadiene is preferably from 1.7 to 2.8, preferably from 2.4 to 2.8.

Also preferred are hydroxyl-terminated polybutadienes having an acrylonitrile content of less than 15%, preferably less than 5%, particularly preferably less than 1%, particularly preferably less than 0.1%. Most preferred is hydroxyl terminated polybutadiene that is free of acrylonitrile.

The total share of polytetramethylene ether glycol and hydroxyl-terminated polybutadiene is at least 95 weight percent, preferably at least 98 weight percent, based on the total weight of the polyol used to prepare the isocyanate-terminated polymer. In a preferred embodiment, only polytetramethylene ether glycol and/or hydroxyl-terminated polybutadiene is used as polyol.

The weight ratio of polytetramethylene ether glycol to hydroxyl-terminated polybutadiene is preferably from 100/0 to 70/30, more preferably from 100/0 to 60/40, more preferably from 100/0 to 90/10, very particularly preferably 100/0.

This has the advantage that higher values of modulus of elasticity, tensile strength, elongation at break, tensile shear strength, angle peel strength and impact peel strength are thereby obtained. This can be seen, for example, in a comparison of examples 2 and 3 in table 3.

In a preferred embodiment, the polyurethane prepolymer is prepared from at least one diisocyanate or triisocyanate and from a polymer Q having terminal amino, mercapto or hydroxyl groups_PMAnd (4) preparing. The preparation of the polyurethane prepolymers is carried out in a manner and manner known to the person skilled in the art of polyurethanes, in particular in which the diisocyanate or triisocyanate is compared with the polymer Q_PMThe amino, mercapto or hydroxyl groups of (a) are used in stoichiometric excess.

The polyurethane prepolymer having isocyanate groups preferably has elastic characteristics. It preferably has a glass transition temperature Tg of less than 0 ℃.

The weight ratio of the at least one epoxy resin A having an average of more than one epoxy group per molecule to the at least one toughening agent D is from 0.3 to 2.2.

A weight ratio of less than 0.3 has the disadvantage that this results in a very slow curing or no curing of the composition at all. Particularly low values of modulus of elasticity, tensile strength values and angular peel strength values are also obtained.

A weight ratio of more than 2.2 has the disadvantage that the compositions thus obtained have low values of impact peel strength and maximum linear expansion.

This can be seen, for example, in table 6.

Preferably, the weight ratio of the at least one epoxy resin a having an average of more than one epoxy group per molecule to the at least one flexibilizer D is from 0.4 to 2.0, particularly preferably from 0.5 to 1.8, most preferably from 0.6 to 1.4. This has the advantage that the compositions thus have high values of peel strength at angles and peel strength at impact.

It is also advantageous that the weight ratio is from 0.3 to 2.2, in particular from 0.4 to 2.2, from 0.6 to 2.2, from 1.0 to 2.2, from 1.4 to 2.2, preferably from 1.8 to 2.2. This has the advantage that the composition thus has high values of modulus of elasticity and tensile strength.

If the weight ratio is from 0.4 to 2.0, in particular from 0.4 to 1.8, preferably from 0.4 to 1.4, more preferably from 0.4 to 1.0, it is advantageous when R is²Selected from the group consisting of

Most preferably

It is also advantageous that the weight ratio is from 0.3 to 2.0, in particular from 0.3 to 1.8, from 0.3 to 1.4, from 0.3 to 1.0, from 0.3 to 0.6, preferably from 0.3 to 0.4. The compositions thus obtained have high maximum linear expansion "max. expansion" values and maximum force values.

In another preferred embodiment, the composition further comprises at least one filler F. It is preferably mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate (precipitated or ground), dolomite, quartz, silica (pyrogenic or precipitated), cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, ceramic hollow spheres, glass hollow spheres, organic hollow spheres, glass spheres, coloring pigments.

Advantageously, the total fraction of all fillers F is from 5 to 40% by weight, preferably from 10 to 30% by weight, based on the total weight of the epoxy resin composition.

In another embodiment, the composition may comprise a physical blowing agent or a chemical blowing agent, such as for example Expancel, under the trade name akzo nobel^TMOr Celogen from Chemtura^TMOr L ehmann&Voss brand nameAnd (4) obtaining. The proportion of blowing agent is generally from 0.1 to 3% by weight, based on the total weight of the epoxy resin composition. The composition preferably has less than 1% by weight, preferably less than 0.5% by weight, particularly preferably less than 0.3% by weight, based on the total weight of the epoxy resin composition%, most preferably less than 0.1% by weight of a physical or chemical blowing agent.

In another preferred embodiment, the composition further comprises at least one reactive diluent G bearing an epoxy group. Such reactive diluents are known to those skilled in the art. Preferred examples of reactive diluents with epoxide groups are:

monofunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain C₄-C₃₀Glycidyl ethers of alcohols such as butanol glycidyl ether, hexanol glycidyl ether, 2-ethylhexanol glycidyl ether, allyl glycidyl ether, tetrahydrofurfuryl glycidyl ether and furfuryl glycidyl ether, trimethoxysilyl glycidyl ether, and the like.

-difunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain C₂-C₃₀Glycidyl ethers of alcohols such as ethylene glycol glycidyl ether, butanediol glycidyl ether, hexanediol glycidyl ether, octanediol glycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, and the like.

Glycidyl ethers of trifunctional or multifunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain alcohols (e.g. epoxidized castor oil, epoxidized trimethylolpropane, epoxidized pentaerythritol), or polyglycidyl ethers of aliphatic polyols (e.g. sorbitol, glycerol or trimethylolpropane), etc.

Glycidyl ethers of phenol compounds and aniline compounds, such as phenyl glycidyl ether, cresyl glycidyl ether, p-tert-butylphenyl glycidyl ether, nonylphenol glycidyl ether, 3-N-pentadecenyl-glycidyl ether (derived from cashew nut shell oil), N-diglycidylaniline, and the like.

Epoxidised amines, such as N, N-diglycidylcyclohexylamine and the like.

Epoxidized mono-or dicarboxylic acids, such as neodecanoic acid-glycidyl ester, glycidyl methacrylate, glycidyl benzoate, diglycidyl phthalate, diglycidyl tetrahydro-and hexahydrophthalate, diglycidyl esters of dimerized fatty acids, and the like.

Epoxidised difunctional or trifunctional, low-to high-molecular-weight polyether polyols, such as polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, etc.

Particular preference is given to hexanediol diglycidyl ether, cresyl glycidyl ether, p-tert-butylphenyl glycidyl ether, polypropylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether.

Advantageously, the total proportion of reactive diluents G having epoxide groups is from 0.1 to 15% by weight, preferably from 0.1 to 5% by weight, particularly preferably from 0.1 to 2% by weight, particularly preferably from 0.2 to 1% by weight, based on the total weight of the epoxy resin composition.

The compositions may comprise further ingredients, in particular catalysts, stabilizers, in particular heat and/or light stabilizers, thixotropic agents, plasticizers, solvents, mineral or organic fillers, blowing agents, colorants and pigments, corrosion inhibitors, surfactants, defoamers and tackifiers.

Suitable plasticizers are, in particular, phenol alkylsulfonates or benzenesulfonic acid-N-butyramides, for exampleOr Dellatol BBS commercially available from Bayer.

Suitable stabilizers are, in particular, optionally substituted phenols, such as BHT orT (Elikem), sterically hindered amines or N-oxyl compounds such as TEMPO (Evonik).

A particularly preferred one-component epoxy resin composition comprises:

10 to 60% by weight, in particular 20 to 40% by weight, based on the total weight of the epoxy resin composition, of an epoxy resin a having an average of more than one epoxy group per molecule; preferably, 60 to 100 wt.%, in particular 60 to 80 wt.%, of the epoxy resin a is a liquid epoxy resin and 0 to 40 wt.%, in particular 20 to 40 wt.%, of the epoxy resin a is a solid epoxy resin;

-at least one latent hardener B for epoxy resins, preferably selected from dicyandiamide, guanidine, anhydrides of polycarboxylic acids, dihydrazides and aminoguanidines and derivatives thereof, of which dicyandiamide is preferred;

-preferably at least one accelerator C selected from substituted ureas, imidazoles, imidazolines and amine complexes, in particular from substituted ureas and amine complexes, particularly preferably substituted ureas;

at least one of the above-mentioned tougheners D, with preference being given to those described above as preferred tougheners D; the content of the toughener D is preferably from 20 to 60% by weight, from 25 to 55% by weight, from 30 to 50% by weight, particularly preferably from 30 to 40% by weight, based on the total weight of the epoxy resin composition;

-preferably from 5 to 40% by weight, preferably from 10 to 30% by weight, of a filler F, preferably selected from wollastonite, calcium carbonate, calcium oxide, a coloring pigment (in particular carbon black) and fumed silica, in particular calcium carbonate, calcium oxide and fumed silica, based on the total weight of the epoxy resin composition;

-preferably from 0.1 to 15% by weight, preferably from 0.1 to 5% by weight, particularly preferably from 0.1 to 2% by weight, particularly preferably from 0.2 to 1% by weight, based on the total weight of the epoxy resin composition, of a reactive diluent G carrying epoxy groups;

-wherein

The weight ratio of the at least one epoxy resin A having on average more than one epoxy group per molecule to the at least one flexibilizer D is from 0.3 to 2.2, from 0.4 to 2.0, particularly preferably from 1.0 to 1.8.

It is also advantageous if the preferred one-component epoxy resin composition has more than 80% by weight, preferably more than 90% by weight, in particular more than 95% by weight, particularly preferably more than 98% by weight, most preferably more than 99% by weight, based on the total weight of the epoxy resin composition, of the abovementioned constituents.

An example of a particularly preferred composition is, for example, example 13 in table 5.

Advantageously, the epoxy resin composition according to the invention has a pressure of 100-10000Pa at 25 ℃^*s, especially 500-^*s, preferably 1000-3000Pa^*s viscosity. Its advantages are high effectIn that a good applicability is thereby ensured. The viscosity is preferably measured as described in the examples section.

Particularly preferred are thermally curable epoxy resin compositions which in the cured state have the following properties:

a tensile shear strength of more than 10MPa, more than 15MPa, more than 20MPa, measured in particular according to DIN EN 1465, particularly preferably as described in the examples section, and/or

A tensile strength of more than 10MPa, more than 15MPa, more than 20MPa, in particular measured according to DIN ENISO 527, particularly preferably as described in the examples section, and/or

An elongation at break of more than 10%, more than 20%, more than 30%, in particular from 30 to 200%, particularly preferably from 30 to 150%, in particular measured in accordance with DIN EN ISO 527, particularly preferably as described in the examples section, and/or

An elastic modulus of 300-.

-an impact peel strength at 23 ℃ of more than 30N/mm, more than 40N/mm, more than 60N/mm, measured in particular according to ISO11343, particularly preferably as described in the examples section, and/or

An angle peel strength of more than 5N/mm, more than 8N/mm, more than 10N/mm, in particular according to DIN53281, particularly preferably as described in the examples section.

It has been found that the heat curable epoxy resin composition is particularly suitable for use as a one-component heat curable adhesive, in particular in vehicle construction and sandwich panel construction. Such one-component adhesives have a wide range of application possibilities. In particular, a thermally curable one-component adhesive having high impact resistance at both high and low temperatures can thereby be realized. Such adhesives are desirable for bonding thermally stable materials.

In particular, such adhesives are first brought into contact with the material to be bonded at a temperature of between 10 ℃ and 80 ℃, in particular between 10 ℃ and 60 ℃, and then cured at a temperature of typically 130-.

A bonded article is obtained by this method described above. The article is preferably a vehicle or a part of a vehicle.

Another aspect of the invention therefore relates to the bonded article obtained by the above-described method. Of course, in addition to the heat-curable adhesive, a sealer can also be realized by the above composition. Furthermore, the method according to the invention is suitable not only for vehicle construction but also for other fields of application. Of particular mention are the relevant applications in vehicles (such as boats, trucks, buses or rail vehicles) or in the construction of articles of everyday use (such as washing machines).

The materials bonded by means of the above-mentioned compositions can be used at temperatures of generally between 120 ℃ and-40 ℃, preferably between 100 ℃ and-40 ℃ and in particular between 80 ℃ and-40 ℃.