Structural adhesives with improved failure modes

Abstract

To provide a structural adhesive composition suitable for adhesion to an oily metal substrate surface, and a structural adhesive film comprising the structural adhesive composition.SOLUTION: A thermosettable structural adhesive composition for adhesion to an oily metal substrate surface comprises: (a) an epoxy compound; (b) a thermoplastic compound; (c) an epoxy curing agent; (d) non-spherical particles of thermally expandable graphite in an amount of 0.1 wt.% or more and less than 10 wt.%, relative to the total weight of the composition; and (e) an inorganic filler selected from the group consisting of MgO, CaO, BaO, K2O, Li2O, Na2O, and a mixture of them.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to a structural adhesive composition suitable for joining parts (e.g., metal parts), and a structural adhesive film comprising the structural adhesive composition. The disclosure further relates to a thermocured structural adhesive film obtained by thermocuring the structural adhesive film according to this disclosure, and a part assembly comprising such a thermocured adhesive film and at least one part. In another embodiment, the disclosure also relates to a method for joining parts (e.g., metal parts / substrates). Furthermore, in a further embodiment, the disclosure relates to the use of such a structural adhesive film for joining parts (e.g., metal parts). [Background technology]

[0002] Metal joints in vehicles may be formed using adhesives. For example, adhesives may be used to bond metal panels, such as roof panels, to the vehicle's support structure or chassis. Furthermore, adhesives may be used to join two metal panels of a vehicle closure panel. A vehicle closure panel typically includes an assembly of an outer metal panel and an inner metal panel, with a hem structure formed by folding the edge of the outer panel over the edge of the inner panel. Typically, adhesive is applied between the panels to bond them together. Furthermore, it is typically necessary to apply a sealant to the joint of the metal panels to provide sufficient corrosion resistance. For example, U.S. Patent No. 6,000,118 discloses the use of fluid sealant beads between the opposing surfaces of two panels and the use of a thin film of uncured paint-like resin between the flange on the outer panel and the exposed surface of the inner panel. The paint film is cured to a solid, opaque state by a baking process performed on the finished door panel. U.S. Patent No. 6,368,008 discloses the use of adhesive to fasten two metal panels together. The edges of the joint are further sealed with a metal coating. International Publication No. 2009 / 071269 discloses an expandable epoxy paste adhesive as a sealant for hem flanges. Further hem-processed structures are disclosed in U.S. Patent No. 6,528,176.

[0003] Further efforts have been made to develop adhesive compositions that can join two metal panels, particularly the outer and inner panels of a vehicle closure panel, with an adhesive that does not require additional material to seal the joint. Thus, it has become desirable to develop an adhesive system that provides sufficient bonding while also sealing the joint and providing corrosion resistance. A partial solution is described, for example, in International Publication 2007 / 014039, which discloses a thermally expandable and curable epoxy precursor for an expandable, heat-cured, film-toughened foamed film. This precursor comprises a mixture of solid and liquid epoxy resins and is claimed to cure to provide desirable energy absorption and gap-filling properties. Another partial solution is described in International Publication 2011 / 141148, which describes a thermally activated structural adhesive. This adhesive is solid and touch-dry at ambient temperature, can be activated at high temperatures to produce adhesive properties, and can be molded without curing.

[0004] Furthermore, it is highly desirable that the thermocured film obtained from the structural adhesive composition exhibits a certain degree of resistance to corrosion and degradation over time. For industrial applications, such as the application of adhesives to oily surfaces and the bonding of parts in a series of processing steps that may include immersion of parts and other liquid compositions of the adhesive, and for the requirements of the bonded assemblies, it is desirable that the adhesive acts under many processing conditions while also providing good performance even after degradation over time. Moreover, while thermosetting structural adhesives can exhibit good adhesive strength, there remains the possibility that the adhesive layer may be destroyed under high loads, for example, by rupture or cracking. In this case, it is highly desirable that the thermocured film exhibits cohesive failure mode rather than adhesive failure mode.

[0005] While we do not dispute the technical advantages of adhesive compositions and adhesive systems disclosed in the art, there remains a need for high-performance structural adhesives that possess a certain degree of handlingability in the uncured state, excellent bonding performance after curing, particularly after exposure to degradation conditions such as high temperature and humidity over a certain period, and exhibit a cohesive failure mode. [Overview of the Initiative]

[0006] According to a first aspect, the disclosure provides a thermosetting structural adhesive composition comprising an epoxy compound, a thermoplastic compound, an epoxy curing agent, and non-spherical particles.

[0007] According to a second aspect, the present disclosure relates to a corrosion-resistant structural adhesive film comprising a structural adhesive composition described herein.

[0008] In another embodiment, the present disclosure relates to a method for joining parts, the method comprising the following steps, namely: i. The process of preparing the first and second parts, ii. The step of applying the structural adhesive composition or structural adhesive film described herein to at least one surface of the first part and / or the second part, iii. A step of forming a joint between the first part and the second part by bonding them at a temperature lower than the activation temperature of the epoxy curing agent, preferably forming a metal joint between the first part and the second part. iv. A step of heating the joint at a temperature higher than the activation temperature of the epoxy curing agent so that the thermosetting composition is heat-cured, This provides a method that includes [something].

[0009] In a further embodiment, the present disclosure relates to a part assembly comprising a first part and a second part, and a thermocured structural adhesive film, wherein the thermocured structural adhesive film has a first portion near the first end of the structural adhesive film and a second portion near the second end opposite the first end of the structural adhesive film. The thermocured structural adhesive film is provided between the first part and the second part and bonds the first part and the second part together, and the thermocured structural adhesive film is obtained by thermocuring a thermosetting composition or structural adhesive film as described herein.

[0010] In yet another embodiment, the disclosure relates to the use of thermosetting compositions or structural adhesive films according to the disclosure for joining parts in industrial applications, preferably in body-in-white processes. [Modes for carrying out the invention]

[0011] Before describing any embodiment of this disclosure in detail, it should be understood that this disclosure is not limited in its intended use to the configuration details and arrangement of components described below. Other embodiments of this disclosure are possible and can be performed or implemented in various ways. As used herein, the terms “a,” “an,” and “the” are interchangeable and mean one or more, and “and / or” is used to indicate that one or both of the described cases may occur, for example, A and / or B includes (A and B) and (A or B). Also herein, a range description by endpoints includes all numbers encompassed within that range (for example, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.). Also herein, a “at least 1” description includes all numbers one or more (for example, at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.). Furthermore, it should be understood that the terminology and grammar used herein are for illustrative purposes only and should not be considered limiting. Unlike the use of "consisting," which is intended to be limiting, the use of "including," "containing," "comprising," or "having," and their variations, is not intended to be limiting, but rather to encompass the elements and additional elements listed thereafter.

[0012] The amounts of components in a composition may be expressed in weight percent (or "%wt." or "wt.%") unless otherwise specified. The total amount of components is 100% by weight unless otherwise specified. When the amount of components is specified in mole percent, the total amount of components is 100% by mole percent unless otherwise specified. In detail, the amount of components may be expressed in parts per 100 parts of fluoroelastomer.

[0013] Unless otherwise explicitly stated, all embodiments of this disclosure can be freely combined.

[0014] According to the first aspect, this disclosure is: (a) epoxy compounds and (b) Thermoplastic compounds and (c) Epoxy curing agent and, (d) Non-spherical particles and The present invention provides a thermosetting structural adhesive composition containing [a specific ingredient].

[0015] Surprisingly, it was found that thermosetting structural adhesive compositions including the above combinations of (a) to (d) can yield thermosetting films exhibiting desired adhesion, such as high peel strength and high overlap shear strength after being subjected to aging degradation conditions, particularly cataplasma conditions, and can even exhibit a cohesive failure mode.

[0016] epoxy compounds The structural adhesive films according to this disclosure preferably comprise a thermosetting composition containing an epoxy compound having an average epoxy equivalent of less than 250 g / equivalent. Suitable epoxy compounds for use herein will be readily identifiable to those skilled in the art in view of this specification.

[0017] In a preferred embodiment, the epoxy compound for use herein has an average epoxy equivalent weight of less than 250 g / equivalent, preferably less than 230 g / equivalent, more preferably less than 220 g / equivalent, and even more preferably less than 200 g / equivalent. Preferably, the epoxy compound for use herein has an average epoxy equivalent weight of 100 - 200 g / equivalent, preferably 150 - 200 g / equivalent, and more preferably 170 - 200 g / equivalent. Even more preferably, the epoxy compound for use herein has a weight-average molecular weight of 700 g / mol or less, preferably 500 g / mol or less, and more preferably 400 g / mol or less. Advantageously, the epoxy compound for use herein has a weight-average molecular weight of 200 - 400 g / mol, preferably 300 - 400 g / mol, and more preferably 350 - 400 g / mol. The epoxy compound for use herein is preferably selected from the group of epoxy compounds having an average epoxy functionality, i.e., an average number of polymerizable epoxy groups per molecule of at least 2, more preferably 2 - 4.

[0018] Any organic compound having at least one oxirane ring polymerizable by a ring-opening reaction can be used as an epoxy compound in the thermosetting composition of the structural adhesive film according to the present disclosure, provided that these organic compounds have an average epoxy equivalent weight of less than 250 g / equivalent. Such materials are widely called epoxies and include monomeric epoxy compounds and polymeric epoxy compounds, and can be aliphatic, alicyclic, aromatic, or heterocyclic. Useful materials generally have at least 2 polymerizable epoxy groups per molecule, more preferably 2 - 4 polymerizable epoxy groups per molecule.

[0019] These epoxy compounds are generally liquid or semi-liquid at room temperature and are often referred to as reactive epoxy thinners or reactive epoxy diluents. These compounds are preferably selected from the group of optionally substituted diglycidyl ethers and polyglycidyl ethers of diphenols and polyphenols, or aliphatic or alicyclic hydroxyl compounds. Suitable epoxy compounds for use herein are commercially available under the trade name Epikote™ 828 from Momentive, under the trade names DER 331, DER 332 and DER 334 from Dow Chemical Co., under the trade name Epon® 828 from Resolution Performance Products, under the trade names Epon® 825 / 826 / 830 / 834 / 863 / 824 from Polysciences, Inc., under the trade name Bakelite® EPR 164 from Hexion, under the trade name Araldite® GY 250 / 260 from Huntsman, or under the trade name EPILOX® A 1900 from Leuna Harze.

[0020] The epoxy compounds useful in the structural adhesive compositions according to the present disclosure are preferably derived from bisphenol A, bisphenol E, bisphenol F, bisphenol S, aliphatic amines and aromatic amines such as methylenedianiline and aminophenol, etc., and halogen-substituted bisphenol resins, novolacs, aliphatic epoxies, and combinations and / or intermediates thereof. More preferably, the organic epoxies are selected from the group comprising diglycidyl ethers of bisphenol A and bisphenol F, and epoxy novolacs.

[0021] The amount of the epoxy compound in the thermosetting structural adhesive composition is preferably included in the range of 20 to 50% by weight, preferably 30 to 50% by weight, more preferably 38 to 50% by weight, based on the total weight of the thermosetting structural adhesive composition.

[0022] Thermoplastic compound The thermosetting structural adhesive compositions according to this disclosure further preferably comprise a thermoplastic compound having a softening point between 60°C and 140°C. Suitable thermoplastic compounds for use herein will be readily identifiable to those skilled in the art in view of this specification. Preferably, the thermoplastic compound is a thermoplastic resin. Therefore, the terms “thermoplastic compound” and “thermoplastic resin” may be used interchangeably in this disclosure. Thermoplastic compounds and thermoplastic resins are often also called film-forming agents.

[0023] In a preferred embodiment, the thermoplastic resins for use herein have a softening point in the range of 70°C to 120°C, preferably 80°C to 100°C, and more preferably 85°C to 95°C. Suitable thermoplastic resins for use herein are preferably selected from the group consisting of polyether thermoplastics, polypropylene thermoplastics, polyvinyl chloride thermoplastics, polyester thermoplastics, polycaprolactone thermoplastics, polystyrene thermoplastics, polycarbonate thermoplastics, polyamide thermoplastics, and any combination thereof.

[0024] Suitable thermoplastic resins for use herein can be advantageously selected from the group of polyether thermoplastic resins, and are preferably polyhydroxyether thermoplastic resins. In a preferred embodiment, the thermoplastic resin for use herein is preferably selected from the group of polyhydroxyether thermoplastic resins, which are selected from the group consisting of phenoxy resins, polyetherdiamine resins, polyvinyl acetal resins, particularly polyvinyl butyral resins, and any combination or mixture thereof. Examples of suitable polyvinyl acetal resins for use herein include vinyl chloride / vinyl acetate copolymers, carboxyl-modified vinyl copolymers, and hydroxyl-modified vinyl copolymers, which are commercially available from Dow Chemicals. In a very preferred embodiment of this disclosure, the thermoplastic resin for use herein is selected from the group of phenoxy resins. Suitable thermoplastic resins for use herein are commercially available from InChem Corporation under the trademark names PKHP, PKHH, PKHA, PKHB, PKHC, PKFE, PKHJ, PKHM-30, or PKHM-301.

[0025] The amount of thermoplastic resin in the thermosetting composition of a structural adhesive film is typically 7 to 40% by weight, preferably 10 to 24% by weight, and more preferably 15 to 24% by weight, based on the total weight of the thermosetting composition.

[0026] Furthermore, the weight ratio of the epoxy compound to the thermoplastic compound, i.e., the thermoplastic resin, is preferably 0.5 to 4, more preferably 1 to 3, more preferably 1.5 to 2.5, and even more preferably 1.8 to 2.2.

[0027] Epoxy hardener The thermosetting compositions for structural adhesive films according to this disclosure further comprise an epoxy curing agent. Any epoxy curing agent well known in the art may be used in the thermosetting compositions for structural adhesives described herein. Preferred epoxy curing agents for use herein are materials that react with the oxirane ring of an organic epoxide to substantially crosslink the epoxide. These materials contain at least one nucleophilic or electrophilic moiety (e.g., an active hydrogen atom) that causes the crosslinking reaction. Epoxide chain extenders primarily remain between the organic epoxide chains and, if present, contribute little to the crosslinking, but epoxy curing agents are distinct from epoxide chain extenders. The epoxy curing agents used herein are also known in the art as epoxy hardeners, epoxide hardeners, catalysts, epoxy curatives, and curatives.

[0028] In some cases, epoxy curing agents and accelerators used to increase the rate of the epoxide curing reaction are distinguished. Accelerators are typically multifunctional materials that are sometimes classified as epoxy curing agents. Therefore, in this specification, no distinction is made between curing agents and accelerators.

[0029] Epoxy curing agents for use herein include those conventionally used to cure epoxy resin compositions and form crosslinked polymer networks. Suitable epoxy curing agents are sometimes called latent curing agents, which are typically selected so as not to react with the epoxy resin until appropriate processing conditions are applied. Such compounds also include aliphatic and aromatic tertiary amines, such as dimethylaminopropylamine and pyridine, which act as catalysts and can generate substantial crosslinking. Furthermore, boron complexes, particularly boron complexes with monoethanolamine, imidazoles such as 2-ethyl-methylimidazole, guanidines such as tetramethylguanidine, dicyanodiamides (often called DICY), substituted ureas such as toluenediisocyanate urea, and acid anhydrides such as 4-methyltetrahydroxyphthalic anhydride, 3-methyltetrahydroxyphthalic anhydride, and methylnorbornenephthalic anhydride. Other useful epoxy curing agents include polyamines, mercaptans, and phenols. Other epoxy curing agents for use herein include encapsulated amines, Lewis salts, transition metal complexes, and molecular sieves. Preferably, the epoxy curing agent is selected from the group consisting of amines, acid anhydrides, guanidine, dicyandiamide, and mixtures thereof. More preferably, the epoxy curing agent contains dicyandiamide. A suitable epoxy curing agent for use herein is commercially available from Air Products under the trademark name Amicure® CG-1200.

[0030] The amount of epoxy curing agent in the thermosetting composition of the structural adhesive film is typically 2 to 15% by weight, preferably 2 to 8% by weight, and more preferably 2 to 4% by weight, based on the total weight of the thermosetting composition.

[0031] Toughening agent In certain embodiments, the thermosetting composition for structural adhesive films may further comprise one or more toughening agents. Any toughening agent well known in the art may be used in the thermosetting composition for structural adhesive films of the present disclosure. The toughening agent is preferably selected from the group consisting of core-shell toughening agents, CTBN (carboxyl and / or nitrile-terminated butadiene / nitrile rubber), and high molecular weight amine-terminated polytetramethylene oxides.

[0032] Particularly preferred core-shell toughening agents typically contain different materials in the inner core region and the outer shell region, respectively. Preferably, the core may be harder than the shell, but this is not essential. The shell may contain a harder material, and / or the shell may be layered within its structure. Most preferably, the inner hard core components consist of one and / or more organic polymers and inorganic oxides from the first, second and / or third transition series of the periodic table, e.g., silica, alumina, zirconia, and / or natural minerals, e.g., feldspar, silicates, aluminates, zirconates, and / or other hardened materials, e.g., carbides, nitrides, silicides, aluminides, and / or some combinations thereof and intermediates. The outer soft shell components may consist of rubber, such as diene rubber, olefin rubber, natural rubber, polyisoprene, polyisoprene copolymers, ethylene propylene monomer rubber, diene-acrylonitrile copolymer, vinyl aromatic monomer copolymer, styrene-butadiene copolymer known as SBR rubber, and diene terpolymers of acrylonitrile or unsaturated ester with styrene or vinyltoluene. The soft shell preferably includes modifications with functional groups such as carboxyl, hydroxyl, epoxy, cyanate, isocyanate, amino, and thiol, which can react with the precursor epoxy components. Core-shell toughening agents useful in thermosetting compositions are commercially available, for example, from Rohm and Hass under the trademark name Paraloid®.

[0033] During curing, the CTBN toughening agent reacts with the precursor epoxide components via its carboxyl and / or nitrile functional groups, thereby introducing these butadiene / nitrile rubber portions into the epoxy network forming the hard segments as soft, impact-absorbing segments. A CTBN toughening agent useful in this disclosure is commercially available, for example, from Hanse Chemie AG (Hamburg, Germany) under the trademark Albipox®.

[0034] High molecular weight amine-terminated polytetramethylene oxides useful in thermosetting compositions are commercially available, for example, from 3M Company (St. Paul / MN, USA) under the trademark name "3M EPX® Rubber".

[0035] The amount of one or more toughening agents present in the thermosetting composition is typically 10 to 40% by weight, preferably 10 to 30% by weight, and more preferably 10 to 20% by weight, based on the total weight of the thermosetting composition.

[0036] In certain embodiments of the structural adhesive compositions according to this disclosure, the weight ratio of the toughening agent to the thermoplastic resin is advantageously within the range of 1 to 4, preferably 1 to 3, more preferably 1.5 to 2.5, and even more preferably 1.8 to 2.2.

[0037] non-spherical particles The structural adhesive compositions according to this disclosure include non-spherical particles. The use of non-spherical particles has the effect of providing the adhesive compositions and adhesive films according to this disclosure with improved failure modes and high mechanical strength. "Failure mode" has a general meaning in the art. That is, a desired "cohesive failure mode" means that failure occurs only in the adhesive layer and not between the adhesive layer and the substrate.

[0038] Non-spherical particles are inorganic particles, preferably made of materials selected from metals, carbon, and glass. The metals are preferably selected from iron, steel, aluminum, titanium, magnesium, and mixtures and alloys thereof. Non-spherical particles made of carbon are preferred. In this regard, graphite and carbon black, particularly graphite, and more preferably thermally expandable graphite, are preferred.

[0039] The particles generally have a non-spherical shape. This has the general meaning used in the art, i.e., the particles are not spherical. Spherical particles generally have an aspect ratio of about 1:1, i.e., one diameter of the particle is approximately the same as a second diameter of the same particle, which is approximately perpendicular to this first diameter of the particle. Therefore, it is preferable that the particles have either an irregular shape or a flake shape. "Irregular shape" has the general meaning used in the art, i.e., particles that do not have any particular symmetry. Flake-shaped particles are preferred in the structural adhesive compositions of this disclosure because they yield the best results with respect to adhesive strength and cohesive failure mode. Preferably, the non-spherical particles described herein have an aspect ratio of at least 1:2.5, preferably in the range of 1:2.5 to 1:20, and more preferably in the range of 1:4 to 1:7. The aspect ratio of a particle refers to the ratio of the diameter or cross-section of the particle to the length of the particle. In other words, the aspect ratio is determined by considering the particle's maximum diameter or maximum length as its length. The particle's diameter is the diameter of the cross-section taken perpendicular to its length. If the cross-section is not circular, the particle's maximum diameter is considered its diameter.

[0040] It was further found that the above effects may be related to the particle size of the non-spherical particles. Particles larger than a certain particle size resulted in undesirable adhesive strength and failure modes compared to the corresponding performance of structural adhesive compositions using non-spherical particles with a particle size of 200 μm or less. Therefore, it is preferable that the non-spherical particles have a particle size of 200 μm or less. Similarly, non-spherical particles must have at least a certain particle size in order to exert some influence on the failure mode. Therefore, it is preferable that the non-spherical particles have a particle size of at least 30 μm. Therefore, it is preferable that the non-spherical particles, preferably flake-shaped particles, have a particle size in the range of 30 μm to 200 μm. In another preferred embodiment of this disclosure, the non-spherical particles have an irregular shape and a particle size of 100 μm or less, preferably 80 μm or less, preferably in the range of 30 μm to 100 μm, more preferably in the range of 30 μm to 80 μm. The particle size is preferably measured as described in ISO 8130-13:2001, the German version EN ISO 8130-13:2010. This part of ISO 8130 specifies a method for determining the spherical equivalent particle size distribution of coating powders by laser diffraction.

[0041] The composition preferably contains non-spherical particles (d) in an amount of 0.1 to 10% by weight, preferably 0.5 to 7% by weight, and more preferably 1.0 to 5% by weight, relative to the total weight of the composition. At amounts less than 0.1% by weight, no significant effect was observed, while at amounts greater than 10% by weight, no increase in effect was observed compared to lower amounts, or undesirable side effects regarding the adhesion of the composition even occurred.

[0042] Examples of suitable non-spherical particles described herein include ES 100C10, ES 20C200, Expan C-8099 lite, Graphite FP 99.5, and Eckart Aluminium.

[0043] Inorganic fillers The structural adhesive compositions according to this disclosure may further comprise at least one inorganic filler capable of absorbing water. Combining such an inorganic filler with an epoxy compound, a thermoplastic resin, an epoxy curing agent, and non-spherical particles has the effect of increasing the corrosion resistance and / or resistance to degradation over time of the compositions and films described herein. In this regard, it is preferable that the inorganic filler is chemically reactive with water. This has a general meaning in the art. That is, by chemically reacting with water, the inorganic filler effectively absorbs water that may come into contact with the structural adhesive composition, whether in an uncured state or more preferably cured, i.e., applied and heat-cured state. While we do not wish to be bound by theory, this unique property of the inorganic fillers described herein is thought to remove water that may penetrate the cured adhesive and, if not removed, could weaken the bonds within the adhesive or the bonds between the adhesive and the substrate.

[0044] The inorganic filler is selected from the group consisting of metal oxides and metal hydroxides, preferably from the group consisting of MgO, CaO, BaO, K2O, Li2O, Na2O, SrO, and mixtures thereof. These compounds have been found to exhibit a particular good water absorption capacity, which is probably due to their ability to chemically react with water. The inorganic filler can be advantageously used as a blend with other compounds, in particular other inorganic fillers. These compounds can act as further reinforcements in structural adhesive compositions or can add strength to adhesives. Therefore, at least one inorganic filler is preferably MgO, CaO, BaO, K2O, Li2O and / or Na2O, more preferably a blend containing MgO, CaO, BaO, K2O, Li2O, Na2O and SiO2, more preferably a blend containing MgO, CaO and SiO2, metal silicates, carbonates, silicates, silicate hydrates (talc), borates, oxides, hydroxides, sulfate titanates, zirconates, and even more preferably a blend containing CaO and SiO2. With respect to SiO2, it is selected from fumed silica, quartz glass, silica gel and quartz, more preferably selected from fumed silica and quartz glass, more preferably quartz glass.

[0045] CaO is commercially available, as is SiO2 in quartz glass. For example, quartz glass is available from Minco Inc. under the trademark name MinSil 20. Hydrophobic fumed silica is commercially available from Degussa as Aerosil (trademark) or from Cabot as CAB-O-Sl (trademark).

[0046] The structural adhesive compositions according to this disclosure preferably contain an inorganic filler in an amount of 0.5 to 50% by weight, preferably 2 to 40% by weight, and more preferably 10 to 30% by weight, relative to the total weight of the composition.

[0047] In a more preferred embodiment of the present disclosure, the structural adhesive composition contains silica, preferably quartz glass, as an inorganic filler component in an amount of 5 to 30% by weight, preferably 10 to 20% by weight, relative to the total weight of the composition, and calcium oxide in an amount of 0.5 to 20% by weight, preferably 2 to 14% by weight, relative to the total weight of the composition.

[0048] Reactive diluent The structural adhesive compositions according to this disclosure preferably further comprise at least one component comprising at least one epoxy moiety and at least one linear or branched alkyl group. These compounds may act as reactive diluents. Thus, the term reactive diluent may be used interchangeably with the term component having at least one epoxy moiety and at least one linear or branched alkyl group. The use of these compounds may have the effect of improving adhesion in general, as well as adhesion to substrate surfaces, particularly metal substrate surfaces, that are at least partially covered with oil. This is particularly useful for industrial applications where metal substrates are bonded to other metal substrates. An example of such a process, where improved adhesion to oily metal surfaces is highly desirable, is the so-called white-body process, commonly used in the automotive industry. While we do not wish to be bound by theory, it is thought that the presence of alkyl groups increases the compatibility between the adhesive and oils that may be present on the metal surface of the substrate in industrial processes. This may have the effect of improving adhesive strength and providing better corrosion protection for the bonded joints. On the other hand, the presence of at least one epoxy group ensures the incorporation of the reactive diluent into the epoxy matrix.

[0049] Preferably, the reactive diluent is formula (I) (R 1 ) n -ABC-(R 2 ) m (Equation (I)) [In the formula, R 1 It is a linear or branched alkyl group. R 2 This is the epoxy part, A, B, and C are different or identical and are linear or branched alkyl, alkoxy, alkene, alkyne, phenyl, phenoxy, or carboxyl molecules, and are optionally substituted with linear or branched alkyl, alkoxy, alkene, alkyne, phenyl, phenoxy, and carboxyl molecules. n is 1, 2, or 2. It is a compound by [m is 1, 2, or 3].

[0050] Furthermore, at least one reactive diluent is a glycidyl ether. In particular, it is preferable that at least one reactive diluent is selected from compounds (i), (ii), and (iii). [ka] [ka] [ka]

[0051] Reactive diluents useful for the structural adhesive compositions according to this disclosure are commercially available under the trademark names Cardolite UltraLite 513, Cardura E10P, and Araldite PY 4122.

[0052] The structural adhesive compositions according to this disclosure preferably contain at least one reactive diluent in an amount of 0.1 to 20% by weight, preferably 1 to 15% by weight, more preferably 1.5 to 10% by weight, and even more preferably 2 to 7% by weight, relative to the total weight of the composition.

[0053] In a preferred embodiment, the structural adhesive composition according to the present disclosure, (a) an epoxy compound in an amount of 20-50% by weight, preferably 30-50% by weight, more preferably 38-50% by weight, preferably with an average epoxy equivalent of less than 250 g / equivalent, preferably less than 230 g / equivalent, more preferably less than 220 g / equivalent, and even more preferably less than 200 g / equivalent, (b) 7 to 40% by weight, preferably 10 to 24% by weight, more preferably 15 to 24% by weight, a thermoplastic compound having a softening point in the range of 60°C to 140°C, (c) 2 to 15% by weight, preferably 2 to 8% by weight, more preferably 2 to 4% by weight of epoxy curing agent, (d) Non-spherical particles in an amount of 0.1 to 10% by weight, preferably 0.5 to 7% by weight, and more preferably 1.0 to 5% by weight, relative to the total weight of the composition, (e) optionally comprising an inorganic filler in an amount of 0.5 to 50% by weight, preferably 2 to 40% by weight, and more preferably 10 to 30% by weight, relative to the total weight of the composition.

[0054] The thermosetting structural adhesive compositions according to this disclosure may optionally include further components, additives, performance modifiers, and / or actionants such as foaming agents, wetting agents, flame retardants, impact modifiers, toughening agents, heat stabilizers, colorants, processing aids, and lubricants.

[0055] Toughening agent In certain embodiments, the thermosetting structural adhesive composition may further comprise one or more toughening agents. Any toughening agent well known in the art may be used in the thermosetting structural adhesive composition of the present disclosure. The toughening agent is preferably selected from the group consisting of core-shell toughening agents, CTBN (carboxyl and / or nitrile-terminated butadiene / nitrile rubber), and high molecular weight amine-terminated polytetramethylene oxides.

[0056] Particularly preferred core-shell toughening agents typically contain different materials in the inner core region and the outer shell region, respectively. Preferably, the core may be harder than the shell, but this is not essential. The shell may contain a harder material, and / or the shell may be layered within its structure. Most preferably, the inner hard core components consist of one and / or more organic polymers and inorganic oxides from the first, second and / or third transition series of the periodic table, e.g., silica, alumina, zirconia, and / or natural minerals, e.g., feldspar, silicates, aluminates, zirconates, and / or other hardened materials, e.g., carbides, nitrides, silicides, aluminides, and / or some combinations thereof and intermediates. The outer soft shell components may consist of rubber, such as diene rubber, olefin rubber, natural rubber, polyisoprene, polyisoprene copolymers, ethylene propylene monomer rubber, diene-acrylonitrile copolymer, vinyl aromatic monomer copolymer, styrene-butadiene copolymer known as SBR rubber, and diene terpolymers of acrylonitrile or unsaturated ester with styrene or vinyltoluene. The soft shell preferably includes modifications with functional groups such as carboxyl, hydroxyl, epoxy, cyanate, isocyanate, amino, and thiol, which can react with the precursor epoxy components. Core-shell toughening agents useful in thermosetting compositions are commercially available, for example, from Rohm and Hass under the trademark name Paraloid®.

[0057] During curing, the CTBN toughening agent reacts with the precursor epoxide components via its carboxyl and / or nitrile functional groups, thereby introducing these butadiene / nitrile rubber portions into the epoxy network forming the hard segments as soft, impact-absorbing segments. A CTBN toughening agent useful in this disclosure is commercially available, for example, from Hanse Chemie AG (Hamburg, Germany) under the trademark Albipox®.

[0058] High molecular weight amine-terminated polytetramethylene oxides useful in thermosetting compositions are commercially available, for example, from 3M Company (St. Paul / MN, USA) under the trademark name "3M EPX® Rubber".

[0059] The amount of one or more toughening agents present in the thermosetting composition is typically 10 to 40% by weight, preferably 10 to 30% by weight, and more preferably 10 to 20% by weight, based on the total weight of the thermosetting composition.

[0060] In certain embodiments of the structural adhesive compositions according to this disclosure, the weight ratio of the toughening agent to the thermoplastic resin is advantageously within the range of 1 to 4, preferably 1 to 3, more preferably 1.5 to 2.5, and even more preferably 1.8 to 2.2.

[0061] foaming agent In certain embodiments, the thermosetting structural adhesive composition may further comprise one or more foaming agents. Any foaming agent well known in the art may be used in the thermosetting structural adhesive composition of the present disclosure.

[0062] By including a foaming agent in a thermosetting structural adhesive film, the structural adhesive composition becomes thermally expandable and is sometimes referred to as an expandable structural adhesive composition. Therefore, upon heating, for example, while the adhesive sheet is heat-cured, the structural adhesive composition expands, assisting in the sealing of any voids in the metal joint. As a result, corrosion resistance can be improved. One or more foaming agents are preferably selected from the group consisting of non-encapsulated and encapsulated foaming agents.

[0063] Non-encapsulated blowing agents are sometimes called chemical blowing agents and release gaseous compounds such as nitrogen, nitrogen oxides, hydrogen, or carboxide dioxide during heating. Useful chemical blowing agents in this disclosure include, for example, azobisisobutyronitrile, azodicarbonamide, carbazide, hydrazide, sodium borohydride, or sodium bicarbonate / citric acid-based non-azo chemical blowing agents, and dinitrosopentamethylenetetramine. The amount of one or more chemical blowing agents is typically 0.2 to 2% by weight, preferably 0.5 to 1.5% by weight, based on the total weight of the thermosetting composition.

[0064] Encapsulating blowing agents typically contain a liquefied gas, such as trichlorofluoromethane, or hydrocarbons, such as n-pentane, isopentane, neopentane, butane, and / or isobutane, encapsulated in a polymer thermoplastic shell. Upon heating, the liquefied gas expands or ruptures the thermoplastic shell, creating a "microballoon." Typically, the amount of one or more encapsulating blowing agents may be advantageously 0.5 to 10% by weight, preferably 1 to 5% by weight, and more preferably 1 to 2% by weight, based on the total weight of the thermosetting composition. Useful encapsulating blowing agents in thermosetting compositions are commercially available, for example, under the trademark Micropearl® from Pierce & Stevens Chemical Corp, Microsphere® from Matsumoto, or ExpanseL® from Akzo Nobel.

[0065] In a particular embodiment, the amount of one or more foaming agents is selected such that, when the structural adhesive film is subjected to a curing temperature higher than the activation (action) temperature of the curing reaction, and measured as described in the section on test methods, it cures to a free expansion coefficient of 50% or less, preferably 40% or less, and more preferably 30% or less, in the structural adhesive composition. More specifically, the amount of one or more foaming agents is selected such that, when cured, it cures to a free expansion coefficient of 10-40%, preferably 10-30%, and more preferably 15-25%, in the structural adhesive composition.

[0066] Another aspect of this disclosure is a corrosion-resistant structural adhesive film comprising a structural adhesive composition described herein.

[0067] The use of structural adhesive films offers several advantages, particularly to users in industrial applications, as such films are especially suitable for automated processing and application by high-speed robotic devices. More specifically, the structural adhesive films of this disclosure enable the efficient automation of the process of forming joints between metal plates, which is of particular interest, for example, in the automotive industry. Furthermore, the structural adhesive films provide good adhesion, such as good T-peel strength and overlap shear strength, even on metal surfaces that are at least partially covered with oil, and maintain good adhesion even under conditions of deterioration over time, such as after wet testing.

[0068] The structural adhesive films according to this disclosure can be easily prepared by many techniques. For example, various components may be added to a suitable internal mixing vessel, such as a Mogul mixer, under ambient conditions. The mixing temperature is not important, and the mixing of the first and second epoxy components and optionally included toughening agent components is typically carried out at a temperature of 80-85°C. When adding the epoxy curing agent component and optionally included foaming agent component, the temperature may be preferably lowered to 70°C or below. After continuing mixing until the components form a homogeneous mixture, the thermosetting structural adhesive composition is removed from the mixer.

[0069] Due to their excellent processability, the thermosetting compositions can be processed into films using conventional coating equipment such as extruders or hot-melt coaters. The thermosetting compositions can be processed into self-supporting films, or alternatively, they can be coated / laminated onto a suitable liner, such as a silicone-treated liner. The structural adhesive films of the present disclosure can be applied to a variety of substrates, such as metals (e.g., Al, Al alloys, titanium, or stainless steel), or other substrates including glass, boron, carbon, Kevlar fibers, epoxy, phenol, cyanate esters, and polyester matrices.

[0070] The structural adhesive films according to this disclosure are typically flexible, shape-conforming films that may or may not be tacky at room temperature. The structural adhesive films are preferably deformable and drapeable before curing, so that they can be applied to curved surfaces and exhibit any two-dimensional shape. The thickness of the structural adhesive films can vary considerably. Useful thicknesses have been found to be in the range of approximately 0.05 mm to 25 mm. For typical bonding of metal panels, the thickness may be in the range of 0.1 to 5 mm, for example, 0.1 to 3 mm, or 0.3 to 1 mm.

[0071] Structural adhesive films may be packaged in the form of rolls of film material, rolls of tape, i.e., narrow, long pieces of material, or stacks of sheets cut to desired dimensions or shapes for end use. If the adhesive film is tacky, a release liner may be inserted between the wraps of adjacent sheets or rolls. Surprisingly, in relation to this disclosure, when structural adhesive films are packaged in the form of rolls of film material, the corresponding rolls of film material have been found to be particularly resistant to leakage (i.e., diffusion of epoxy resin in the case of rolls of film) during storage. While we do not wish to be constrained by theory, it is thought that the long polymer chains contained in the thermoplastic resin are involved in retaining the epoxy resin in the structural adhesive film during storage. More specifically, when packaged in the form of a roll of film material having a length of more than 100 meters, preferably more than 200 meters, more preferably more than 300 meters, even more preferably more than 500 meters, even more preferably more than 700 meters, and even more preferably more than 800 meters, and a width typically comprising 5 to 40 mm, particularly 10 to 30 mm, and especially 10 to 20 mm, the structural adhesive films of the present disclosure remain leak-proof.

[0072] The structural adhesive films of this disclosure may comprise one or more layers. The adhesive film may also comprise a net or carrier layer. Suitable nets or carrier layers include open cloths or fabrics made of polymer materials. The carrier layer preferably comprises cotton, glass, polyester, polyamide, polypropylene, polyurethane, polyethylene, polyviscose, carbon fiber, aramid fiber, metal, and any combination and mixture thereof. Generally, the nets may be flexible and stretchable. A specific example is a heat-set, flexible and stretchable open nylon knit fabric. The nets may have a thickness of 1 to 15 g / m². 2 For example, 5-12 g / m 2 This is possible. A useful material is 3M® Scotch-Weld® 3336, available from 3M Co. Structural adhesive films may also include an open nonwoven fabric layer such as scrim.

[0073] The structural adhesive films according to this disclosure are suitable for providing any of the following benefits, selected from the group consisting of dimensional stability, flexibility, robustness, handling, suitability for automated processing and application, and hot water washability in the uncured state, and excellent bonding and sealing performance, high mechanical strength, water-impermeable properties, gap-filling properties, controlled expansion behavior, and a smooth finish after curing.

[0074] As is evident from the above, structural adhesive films may also consist solely of the structural adhesive compositions described herein. Therefore, the advantages and effects described in relation to the compositions also apply to the films, and vice versa.

[0075] The structural adhesive compositions and structural adhesive films according to this disclosure preferably provide, in a steel substrate at least partially covered with oil, overlap shear strengths according to DIN EN 1465 of at least 21 MPa at -40°C and / or at least 17 MPa at 23°C and / or at least 11 at 80°C.

[0076] Similarly, the structural adhesive compositions and structural adhesive films according to the present disclosure preferably provide a T-type peel strength of at least 165 N, preferably at least 170 N, and more preferably at least 175 N, according to ASTM D1876, on a steel substrate that is at least partially covered with oil.

[0077] The structural adhesive compositions and structural adhesive films according to this disclosure preferably result in a reduction in overlap shear strength according to DIN EN 1465 of 30% or less, preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less, after wetting conditions in a steel substrate covered at least partially with oil.

[0078] In another embodiment, the present disclosure relates to a method for joining parts, the method comprising the following steps, namely: i. The process of preparing the first and second parts, ii. The step of applying the structural adhesive composition or structural adhesive film described herein to at least one surface of the first part and / or the second part, iii. A step of forming a joint between the first part and the second part by bonding them at a temperature lower than the activation temperature of the epoxy curing agent, preferably forming a metal joint between the first part and the second part. iv. A step of heating the joint at a temperature higher than the activation temperature of the epoxy curing agent so that the thermosetting composition is heat-cured, This provides a method that includes [something].

[0079] In a preferred embodiment, the material of the first component is the same as the material of the second component. In another preferred embodiment, the material of the first component is different from the material of the second component. Preferably, the material of the first component and / or the second component is selected from metal, carbon, polymer material, composite material, wood, and glass.

[0080] Preferably, the first part and at least one of the second part include metal, preferably a metal panel. The metal is preferably selected from steel, stainless steel, galvanized steel, nickel-plated steel, chromium-plated steel, titanium, aluminum, zinc, magnesium, and alloys thereof, and any combination thereof. With regard to industrial processes, particularly applications in the automotive industry, at least one surface of the first part and / or the second part is covered with oil.

[0081] In another embodiment, the present disclosure relates to a method for joining metal parts, wherein the method is a) Prepare a first metal part and a second metal part (where one of the first metal part and the second metal part includes a metal panel), b) To provide the above structural adhesive film, c) Forming a metal joint by bonding the first metal part and the second metal part at a temperature lower than the activation temperature of the epoxy curing agent, d) Heating the metal joint to a temperature higher than the activation temperature of the epoxy curing agent so as to heat-cur the thermosetting composition of the structural adhesive film, This includes methods.

[0082] In yet another aspect, the present disclosure relates to a method for manufacturing a metal parts assembly, wherein the method is a) Prepare a first metal part and a second metal part (where one of the first metal part and the second metal part includes a metal panel), b) To provide a structural adhesive film according to any of the above claims, c) To form a metal joint by bonding the first metal part and the second metal part together, d) Heating the metal joint to heat-cur the thermosetting composition of the structural adhesive film, This includes methods.

[0083] In a preferred embodiment of the method according to this disclosure, the metal components are automotive panels joined together at their edges to form a so-called hemmed structure or hem flange.

[0084] Typically, the joints of metal panels for vehicle closure panels are formed early in the manufacturing process, and the panels are often contaminated with, for example, grease or oil. The structural adhesive films used in connection with this method typically provide corrosion resistance by bonding the metal parts and metal panels to a sufficient level while also providing good sealing properties on the joint.

[0085] Furthermore, structural adhesive films can generally be applied to metal parts and metal panels that may be contaminated to some extent, for example, with oil, and generally do not require cleaning of the parts or panels before application of the adhesive sheet. Application of structural adhesive films by automated equipment such as robot heads is also conceivable. Moreover, an initial adhesive bond of sufficient strength can be formed so that the metal parts can be held together without the need for clamping and fixing during further processing of the joint or manufacturing processes such as painting, and before thermal curing and the formation of the final and permanent bond.

[0086] The final adhesive bond is advantageous in that it has good impact resistance and, preferably, good elongation at break so that any stress that may be generated at the joint can be absorbed without causing the bond to break. Furthermore, the structural adhesive film according to this disclosure is sufficiently resistant to washing, and therefore the metal parts joints joined by the adhesive sheet can be subjected to cleaning operations, for example, which may be necessary before painting.

[0087] In another manner, this disclosure, (I) The first part and the second part, (II) comprising a thermocured structural adhesive film, The thermocured structural adhesive film has a first portion near the first end of the structural adhesive film and a second portion near the second end opposite the first end of the structural adhesive film. The present invention provides a component assembly in which a thermocured structural adhesive film is provided between a first component and a second component, bonding the first component and the second component together, and the thermocured structural adhesive film is obtained by the thermocuring of a thermosetting structural adhesive composition or structural adhesive film according to the present disclosure.

[0088] Preferably, the component assembly can be obtained by the method described herein. Accordingly, the materials and applications described above for the method and preferred embodiments of the present disclosure also apply to the component assemblies described herein.

[0089] Furthermore, the structural adhesive compositions and structural adhesive films according to this disclosure exhibit desirable properties such as high adhesive performance even on oily substrates and high corrosion resistance, making them excellently suitable for joining parts in various industrial applications. Accordingly, this disclosure provides the use of the structural adhesive compositions or structural adhesive films described herein for joining parts in industrial applications, preferably in a white-body process. This use preferably involves the thermocured structural adhesive film producing a joined metal part assembly exhibiting overlap shear strengths of at least 21 MPa at -40°C and / or at least 17 MPa at 23°C and / or at least 11 at 80°C, according to DIN EN 1465.

[0090] Exemplary Embodiments The following are numbered exemplary embodiments illustrating the present disclosure.

[0091] Embodiment 1. (a) epoxy compounds and (b) Thermoplastic compounds and (c) Epoxy curing agent and, (d) Non-spherical particles and A thermosetting structural adhesive composition containing [the specified ingredient].

[0092] Embodiment 2. The structural adhesive composition according to Embodiment 1, wherein the non-spherical particles are inorganic particles.

[0093] Embodiment 3. The structural adhesive composition according to Embodiment 1 or 2, wherein the non-spherical particles are made of a material selected from metal, carbon, and glass.

[0094] Embodiment 4. The structural adhesive composition according to Embodiment 3, wherein the metal is selected from iron, steel, aluminum, titanium, magnesium, and mixtures and alloys thereof.

[0095] Embodiment 5. The structural adhesive composition according to Embodiment 3, wherein the carbon is selected from graphite and carbon black, preferably graphite, and more preferably thermally expandable graphite.

[0096] Embodiment 6. A structural adhesive composition according to any one of Embodiments 1 to 5, wherein the non-spherical particles have an irregular shape or a flake shape.

[0097] Embodiment 7. A structural adhesive composition according to any one of Embodiments 1 to 8, wherein the non-spherical particles have an aspect ratio of at least 1:2.5, preferably in the range of 1:1.25 to 1:20, and more preferably in the range of 1:4 to 1:7.

[0098] Embodiment 8. A structural adhesive composition according to any one of Embodiments 1 to 7, wherein the particle size of the non-spherical particles is 200 μm or less.

[0099] Embodiment 9. A structural adhesive composition according to any one of Embodiments 1 to 8, wherein the particle size of the non-spherical particles is at least 30 μm.

[0100] Embodiment 10. A structural adhesive composition according to any one of Embodiments 1 to 9, wherein the particle size of the non-spherical particles is in the range of 30 μm to 200 μm.

[0101] Embodiment 11. A structural adhesive composition according to any one of Embodiments 1 to 10, wherein the non-spherical particles have a flake shape and a particle size in the range of 30 μm to 200 μm.

[0102] Embodiment 12. A structural adhesive composition according to any one of Embodiments 1 to 11, wherein the non-spherical particles have an irregular shape and a particle size of 100 μm or less, preferably 80 μm or less, and more preferably in the range of 30 μm to 80 μm.

[0103] Embodiment 13. A structural adhesive composition according to any one of Embodiments 1 to 12, further comprising at least one inorganic filler (e) that can absorb water, preferably chemically react with water.

[0104] Embodiment 14. The structural adhesive composition according to Embodiment 13, wherein the inorganic filler (e) is selected from the group consisting of metal oxides and metal hydroxides, preferably from the group consisting of MgO, CaO, BaO, K2O, Li2O, Na2O, SrO, and mixtures thereof.

[0105] Embodiment 15. A structural adhesive composition according to Embodiment 13 or 14, wherein at least one inorganic filler (e) is MgO, CaO, BaO, K2O, Li2O and / or Na2O, preferably a blend containing MgO, CaO, BaO, K2O, Li2O, Na2O and SiO2, more preferably a blend containing MgO, CaO and SiO2, metal silicates, carbonates, silicates, silicate hydrates (talc), borates, oxides, hydroxides, titanate sulfates, zirconates, and even more preferably a blend containing CaO and SiO2.

[0106] Embodiment 16. The structural adhesive according to Embodiment 15, wherein SiO2 is selected from fumed silica, quartz glass, silica gel, and quartz, preferably selected from fumed silica and quartz glass, and more preferably quartz glass.

[0107] Embodiment 17. A structural adhesive composition according to any one of Embodiments 1 to 16, further comprising at least one component (f) comprising at least one epoxy moiety and at least one linear or branched alkyl group.

[0108] Embodiment 18. A structural adhesive composition according to any one of Embodiments 1 to 17, wherein the composition contains non-spherical particles (d) in an amount of 0.1 to 10% by weight, preferably 0.5 to 7% by weight, and more preferably 1.0 to 5% by weight, relative to the total weight of the composition.

[0109] Embodiment 19. A structural adhesive composition according to any one of Embodiments 1 to 18, wherein the composition contains at least one component (f) in an amount of 0.1 to 20% by weight, preferably 1 to 15% by weight, more preferably 1.5 to 10% by weight, and even more preferably 2 to 7% by weight, relative to the total weight of the composition.

[0110] Embodiment 20. A structural adhesive composition according to any one of Embodiments 1 to 19, wherein the composition comprises at least one inorganic filler (e) in an amount of 0.5 to 50% by weight, preferably 2 to 40% by weight, and more preferably 10 to 30% by weight, relative to the total weight of the composition.

[0111] Embodiment 21. The structural adhesive composition according to Embodiment 20, wherein the composition contains silica, preferably quartz glass, as an inorganic filler component (e) in an amount of 5 to 30% by weight, preferably 10 to 20% by weight, relative to the total weight of the composition, and calcium oxide in an amount of 0.5 to 20% by weight, preferably 2 to 14% by weight, relative to the total weight of the composition.

[0112] Embodiment 22. Epoxy compound (a) A structural adhesive composition according to any one of Embodiments 1 to 21, wherein the average epoxy equivalent of the epoxy compound is less than 250 g / equivalent, preferably less than 230 g / equivalent, more preferably less than 220 g / equivalent, and even more preferably less than 200 g / equivalent.

[0113] Embodiment 23. A structural adhesive composition according to any one of Embodiments 1 to 22, wherein the softening point of the thermoplastic resin is in the range of 30°C to 140°C.

[0114] Embodiment 24. A structural adhesive composition according to any one of Embodiments 1 to 23, wherein the weight ratio of epoxy compound (a) to thermoplastic resin (b) is 0.5 to 4, preferably 1 to 3, more preferably 1.5 to 2.5.

[0115] Embodiment 25. The structural adhesive composition according to any one of Embodiments 1 to 24, wherein the thermoplastic resin (b) is selected from polyethersulfone, polymethyl (meth) acrylate, acrylonitrile butadiene styrene, nylon, polylactic acid, polybenzimidazole, polyetherimide, polyethylene, polyhydroxyether, preferably selected polyphenylene oxide, polypropylene, polystyrene, polyvinyl chloride and fluorinated polymer, preferably polyethersulfone, polyhydroxyether and preferably phenoxy resin.

[0116] Embodiment 26. The composition comprises (a) 20 to 50% by weight, preferably 30 to 50% by weight, more preferably 38 to 50% by weight of an epoxy compound having a preferably average epoxy equivalent of less than 250 g / equivalent, preferably less than 230 g / equivalent, more preferably less than 220 g / equivalent, even more preferably less than 200 g / equivalent, and (b) 7 to 40% by weight, preferably 10 to 24% by weight, more preferably 15 to 24% by weight of a thermoplastic compound having a preferably softening point in the range of 60°C to 140°C, and (c) 2 to 15% by weight, preferably 2 to 8% by weight, more preferably 2 to 4% by weight of an epoxy curing agent, and (d) 0.1 to 10% by weight, preferably 0.5 to 7% by weight, more preferably 1.0 to 5% by weight of non-spherical particles based on the total weight of the composition, and (e) optionally, 0.5 to 50% by weight, preferably 2 to 40% by weight, more preferably 10 to 30% by weight of an inorganic filler based on the total weight of the composition, and The structural adhesive composition according to any one of Embodiments 1 to 25.

[0117] Embodiment 27. At least one constituent (f) has the formula (I) (R 1 ) n -A-B-C-(R 2 ) m (Formula (I)) [Wherein, R 1 It is a linear or branched alkyl group. R 2 This is the epoxy part, A, B, and C are different or identical and are linear or branched alkyl, alkoxy, alkene, alkyne, phenyl, phenoxy, or carboxyl molecules, and are optionally substituted with linear or branched alkyl, alkoxy, alkene, alkyne, phenyl, phenoxy, and carboxyl molecules. n is 1, 2, or 2. A structural adhesive composition according to any one of Embodiments 1 to 26, wherein m is a compound of [1, 2, or 3].

[0118] Embodiment 28. The structural adhesive composition according to Embodiment 27, wherein at least one component (f) is a glycidyl ether.

[0119] Embodiment 29. At least one component (f) is a component [ka] [ka] [ka] Furthermore, structural adhesive compositions according to Embodiment 27 or 28, selected from mixtures and derivatives thereof.

[0120] Embodiment 30. A structural adhesive composition according to any one of Embodiments 1 to 29, which induces a cohesive failure mode in a T-type peel test according to ASTM D1876.

[0121] Embodiment 31. A structural adhesive composition according to any one of Embodiments 1 to 30, which provides overlap shear strengths according to DIN EN 1465 of at least 21 MPa at -40°C and / or at least 17 MPa at 23°C and / or at least 11 at 80°C.

[0122] Embodiment 32. A structural adhesive composition according to Embodiment 30, which provides overlap shear strengths according to DIN EN 1465 of at least 21 MPa at -40°C and / or at least 17 MPa at 23°C and / or at least 11 at 80°C in a steel substrate at least partially covered with oil.

[0123] Embodiment 33. A structural adhesive composition according to any one of Embodiments 1 to 32, which yields a T-type peel strength of at least 165 N, preferably at least 170 N, and more preferably at least 175 N, according to ASTM D1876.

[0124] Embodiment 34. A structural adhesive composition according to Embodiment 33, which provides a T-type peel strength of at least 165 N, preferably at least 170 N, and more preferably at least 175 N, according to ASTM D1876, on a steel substrate that is at least partially covered with oil.

[0125] Embodiment 35. A structural adhesive composition according to any one of Embodiments 1 to 34, which, after wet conditions, results in a reduction in overlap shear strength by 30% or less, preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less, according to DIN EN 1465.

[0126] Embodiment 36. The structural adhesive composition according to Embodiment 35, wherein the base material includes steel, more preferably HD steel and / or ELO steel, and even more preferably HD steel.

[0127] Embodiment 37. A structural adhesive film comprising the structural adhesive composition described in any one of Embodiments 1 to 36.

[0128] Embodiment 38. A structural adhesive film according to Embodiment 37, comprising the structural adhesive composition according to any one of Embodiments 1 to 36.

[0129] Embodiment 39. A structural adhesive film according to Embodiment 37 or 38, which is a corrosion-resistant structural adhesive film.

[0130] Embodiment 40. A structural adhesive film according to any one of Embodiments 37 to 39, which provides overlap shear strengths according to DIN EN 1465 of at least 21 MPa at -40°C and / or at least 17 MPa at 23°C and / or at least 11 at 80°C.

[0131] Embodiment 41. A structural adhesive film according to Embodiment 40, which provides overlap shear strengths according to DIN EN 1465 of at least 21 MPa at -40°C and / or at least 17 MPa at 23°C and / or at least 11 at 80°C on a steel substrate at least partially covered with oil.

[0132] Embodiment 42. A structural adhesive film according to any one of Embodiments 37 to 41, which yields a T-type peel strength of at least 165 N, preferably at least 170 N, and more preferably at least 175 N, according to ASTM D1876.

[0133] Embodiment 43. A structural adhesive film according to Embodiment 42, which provides a T-type peel strength of at least 165 N, preferably at least 170 N, and more preferably at least 175 N, according to ASTM D1876, on a steel substrate that is at least partially covered with oil.

[0134] Embodiment 44. A structural adhesive film according to any one of Embodiments 37 to 43, which, after wet conditions, results in a reduction in overlap shear strength by 30% or less, preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less, according to DIN EN 1465.

[0135] Embodiment 45. The structural adhesive film according to Embodiment 44, wherein the base material includes steel, more preferably HD steel and / or ELO steel, and even more preferably HD steel.

[0136] Embodiment 46. A structural adhesive film according to any one of Embodiments 37 to 45, further comprising at least one carrier layer, preferably a porous carrier layer preferably selected from woven fabric, knitted fabric, or nonwoven fabric.

[0137] Embodiment 47. A structural adhesive film according to Embodiment 46, wherein the carrier layer comprises cotton, glass, polyester, polyamide, polypropylene, polyurethane, polyethylene, polyviscose, carbon fiber, aramid fiber, metal, and any combination or copolymer thereof.

[0138] Embodiment 48. A method for joining parts, wherein the method comprises the following steps, namely, i. The process of preparing the first and second parts, ii. A step of applying a structural adhesive composition according to any one of Embodiments 1 to 36, or a structural adhesive film according to any one of Embodiments 37 to 47, to at least one surface of a first part and / or a second part; iii. A step of forming a joint between the first part and the second part by bonding them at a temperature lower than the activation temperature of the epoxy curing agent, preferably forming a metal joint between the first part and the second part. iv. A step of heating the joint at a temperature higher than the activation temperature of the epoxy curing agent so that the thermosetting composition is heat-cured, Methods that include...

[0139] Embodiment 49. The method according to Embodiment 48, wherein at least one of the first and second components is made of metal.

[0140] Embodiment 50. The method according to Embodiment 48 or 49, wherein at least one of the first and second components is a panel.

[0141] Embodiment 51. The method according to any one of embodiments 48 to 50, wherein at least one of the first and second components includes a metal panel.

[0142] Embodiment 52. The method according to any one of Embodiments 48 to 51, wherein the material of the first component is the same as the material of the second component.

[0143] Embodiment 53. The method according to any one of Embodiments 48 to 50, wherein the material of the first part is different from the material of the second part.

[0144] Embodiment 54. The method according to any one of Embodiments 48 to 53, wherein the material of the first part and / or the second part is selected from metal, carbon, polymer material, composite material, wood, and glass.

[0145] Embodiment 55. The method according to any one of Embodiments 48 to 54, wherein at least one of the first and second components is made of a material that does not contain metal.

[0146] Embodiment 56. The method according to Embodiment 54, wherein the metal is selected from steel, stainless steel, galvanized steel, nickel-plated steel, titanium, aluminum, zinc, magnesium, and alloys thereof, as well as combinations thereof.

[0147] Embodiment 57. The method according to any one of Embodiments 48 to 56, wherein the metal of the first metal part is different from the metal of the second metal part.

[0148] Embodiment 58. The method according to any one of Embodiments 48 to 56, wherein the metal of the first metal part is the same as the metal of the second metal part.

[0149] Embodiment 59. The method according to any one of Embodiments 48 to 58, wherein the metal of the first metal part is steel, stainless steel, galvanized steel, or nickel-plated steel, and the metal of the second metal part is steel, preferably stainless steel, galvanized steel, or nickel-plated steel.

[0150] Embodiment 60. The method according to any one of Embodiments 48 to 59, wherein the metal of the first metal part is steel, stainless steel, galvanized steel, or nickel-plated steel, and the metal of the second metal part is aluminum, titanium, or an alloy containing one or both aluminum and / or titanium.

[0151] Embodiment 61. The method according to any one of Embodiments 48 to 60, wherein at least one surface of the first part and / or the second part is covered with oil.

[0152] Embodiment 62. (I) The first part and the second part, (II) comprising a thermocured structural adhesive film, The thermocured structural adhesive film has a first portion near the first end of the structural adhesive film and a second portion near the second end opposite the first end of the structural adhesive film. A component assembly in which a thermocured structural adhesive film is provided between a first component and a second component, bonding the first component and the second component together, wherein the thermocured structural adhesive film is obtained by thermocuring a thermosetting composition according to any one of embodiments 1 to 36 or a structural adhesive film according to any one of embodiments 37 to 47.

[0153] Embodiment 63. The component assembly according to Embodiment 62, wherein the thermocured structural adhesive film exhibits overlap shear strengths of at least 21 MPa at -40°C and / or at least 17 MPa at 23°C and / or at least 11 MPa at 80°C, according to DIN EN 1465.

[0154] Embodiment 64. The component assembly according to Embodiment 62 or 63, wherein the thermocured structural adhesive film exhibits a t-type peel strength of at least 165 N, preferably at least 170 N, and more preferably at least 175 N according to ASTM D1876.

[0155] Embodiment 65. A component assembly according to any one of Embodiments 62 to 64, wherein the material of the first component and / or the second component is selected from metal, carbon, polymer material, composite material, wood, and glass.

[0156] Embodiment 66. A component assembly according to any one of embodiments 62 to 65, wherein at least one of the first component and the second component is a panel.

[0157] Embodiment 67. A component assembly according to any one of Embodiments 62 to 66, wherein the material of the first component is the same as the material of the second component.

[0158] Embodiment 68. A component assembly according to any one of Embodiments 62 to 66, wherein the material of the first component is different from the material of the second component.

[0159] Embodiment 69. A component assembly according to any one of Embodiments 62 to 68, wherein the metal is selected from steel, preferably stainless steel, galvanized steel, nickel-plated steel, titanium, aluminum, zinc, magnesium, and alloys thereof.

[0160] Embodiment 70. The component assembly according to Embodiment 69, wherein the metal of the first metal component is different from the metal of the second metal component.

[0161] Embodiment 71. The component assembly according to Embodiment 69, wherein the metal of the first metal component is the same as the metal of the second metal component.

[0162] Embodiment 72. A component assembly according to any one of Embodiments 62 to 71, wherein the metal of the first metal component is steel, preferably stainless steel, galvanized steel, or nickel-plated steel, and the metal of the second metal component is steel, preferably stainless steel, galvanized steel, or nickel-plated steel.

[0163] Embodiment 73. A component assembly according to any one of Embodiments 62 to 71, wherein the metal of the first metal component is steel, preferably stainless steel, galvanized steel, or nickel-plated steel, and the metal of the second metal component is aluminum, titanium, or an alloy containing one or both aluminum and / or titanium.

[0164] Embodiment 74. A component assembly according to any one of Embodiments 62 to 69, wherein the material of the first component is metal and the material of the second component is a composite material or carbon.

[0165] Embodiment 75. Use of a thermosetting structural adhesive composition as defined in any one of Embodiments 1 to 36, or a thermosetting structural adhesive film as defined in any one of Embodiments 37 to 47, for joining parts in an industrial application, preferably in a white-body process.

[0166] Embodiment 76. Use of the thermosetting structural adhesive composition specified in Embodiment 64 for the thermosetting structural adhesive film specified in Embodiment 75 for the fabrication of a bonded metal parts assembly, wherein the thermosetting structural adhesive film exhibits an overlap shear strength of at least 21 MPa at -40°C and / or at least 17 MPa at 23°C and / or at least 11 at 80°C, according to DIN EN 1465.

[0167] Embodiment 77. Use according to Embodiment 75 or 76 to induce a cohesive failure mode in the adhesive layer.

[0168] Embodiment 78. An use according to any one of Embodiments 75 to 77, wherein the use includes joining parts in a hem flange process, preferably in the automotive industry. [Examples]

[0169] The present disclosure will be further explained, but is not intended to limit it thereto. The following examples are presented to illustrate specific embodiments, but are not intended to limit them in any way. Before that, some test methods used to characterize the materials and their properties will be described.

[0170] method Overlap shear strength according to DIN EN 1465 (published in 2009). The overlapping shear strength was measured according to DIN EN 1465 using a Zwick Z050 tensile testing machine (commercially available from Zwick GmbH & Co.KG (Ulm, Germany)) at a crosshead speed of 10 mm / min, yielding a result of 3 g / m². 2Measurements are taken on a 100mm × 25mm × 0.8mm hot-dip galvanized steel strip (commercially available as DX 54D-Z100 from ThyssenKrupp Steel (Germany)) coated with oil (PL 3802-39S, commercially available from Fuchs Petrolub AG (Germany)). To prepare the overlap shear strength test assembly, the epoxy film to be tested (0.4mm thick) is applied to one end of the first steel strip and covered with the second steel strip to form a 10mm overlap joint. The overlap joint is then clamped and secured together using two binder clips, and the test assembly is placed in an air-circulating furnace with a minimum scorching cycle of 160°C for 20 minutes and a maximum scorching cycle of 200°C for 45 minutes. The test assembly is heated and cooled in this manner using a gradient of 3°C / min. Next, prior to testing, the test assembly is conditioned for 24 hours under ambient conditions of 23±2°C and 50±% relative humidity. Since the test temperature for measuring overlap shear strength varies from -40°C to room temperature, up to a maximum of +80°C, the test assembly is placed in an environmental chamber (commercially available from RS Simulatoren (Oberhausen, Germany)) before testing on the Zwick tensile testing machine, and the overlap shear strength is measured at -40°C, room temperature (23°C±2°C), and +80°C. Three samples are measured for each of the three different test temperature examples, the results are averaged, and reported in MPa units.

[0171] Adhesive peel strength according to ASTM 1876 (issued in 2008). The adhesive peel strength was determined according to ASTM 1876 using a Zwick Z050 tensile testing machine (commercially available from Zwick GmbH & Co.KG (Ulm, Germany)) at a rate of 3 g / m². 2Measurements were taken on a 150mm × 25mm × 0.8mm hot-dip galvanized steel strip (commercially available as DX 54D-Z100 from ThyssenKrupp Steel (Germany)) coated with oil (PL 3802-39s, commercially available from Fuchs Petrolub AG (Germany)). The crosshead speed was set to 100mm / min for all measurements, and the adhesive peel strength was measured at 23°C ± 2°C and 50 ± 5% relative humidity. To prepare the test assembly, masking tape (Scotch® 2610 Masking Tape, commercially available from 3M (USA)) was applied to the first steel strip. The masking tape was applied in this way to visualize the bonding area. The bonding area had dimensions of 100mm × 25mm. Next, the material of the example to be tested was applied to the marked bonding area and covered with a second steel strip of the same dimensions as the first steel strip. Next, to hold the test assembly in place, the two strips are first pressed together manually, and then the two binder clips are used to clamp and secure them together along the bond line. The test assembly is cured in an air-circulating furnace with a minimum curing cycle of 20 minutes at 160°C and a maximum curing cycle of 45 minutes at 200°C. In this way, the test assembly is heated and cooled using a gradient of 3°C / min. Then, prior to testing, the test assembly is conditioned for 24 hours under ambient conditions of 23±2°C and 50±5% relative humidity. Three adhesive peel strength test assemblies are prepared for each material of the example, and the test results are averaged. The results are reported in N / 25mm units.

[0172] Wetness test: For the overlap shear test, the test specimens described above were prepared, wrapped in water-soaked cotton wool, and then airtightly sealed in polyethylene bags. These samples were then stored at 70°C and 100% relative humidity for 7 days. After unwrapping the samples, the test specimens were stored at 23°C for 2 hours, followed by storage at -28°C for 2 hours. Subsequently, after reconditioning under a standard atmosphere, the overlap shear test was performed as described above. The test results were compared with the initial standard sample, which was not subjected to the humid conditions described herein.

[0173] Destruction mode: As described above, samples were prepared for overlapping shear strength. Then, the overlapping shear strength was measured as described above until the strap separated, i.e., until the sample broke. The samples were visually inspected with the naked eye as follows. If the fracture was completely within the adhesive layer, the fracture mode was considered to be "cohesive fracture". However, if the fracture was confirmed by the separation of at least a portion of the adhesive layer from the metal substrate, the fracture mode was considered to be "adhesive fracture". From an application standpoint, the "cohesive fracture mode" is very desirable and therefore highly preferred. [Table 1]

[0174] Preparation of Examples and Comparative Examples The epoxy compositions of this disclosure are prepared by mixing the components from the list of materials in Table 1 in a high-speed mixer (DAC 150 FVZ Speedmixer, from Hauschild Engineering) at 3000 rpm. In Table 2, all concentrations are shown in weight percent.

[0175] In the first step, the epoxy resin, thermoplastic phenoxy resin, and core-shell toughening agent are mixed together for 2 minutes to obtain a masterbatch formulation in the ratios shown in Table 2. This masterbatch is then placed in an air-circulating furnace at 95°C for approximately 1 hour. The heated mixture is then stirred again in a high-speed mixer at 3000 rpm for 2 minutes to ensure complete dispersion of the three components. The mixer temperature is then reduced to 60°C, and the two curing agents are added to the mixture along with the additional components shown in Table 3, followed by mixing under reduced pressure for a further 2 minutes. The resulting mixture is a paste with uniform viscosity. The mixer is heat-coated using a knife coater to form a film with a thickness of 0.4 mm. The formed film is flexible and homogeneous upon cooling. [Table 2] Table 3 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 10 Table 11

Claims

1. (a) epoxy compounds and (b) Thermoplastic compounds and (c) Epoxy curing agent, (d) Non-spherical particles of thermally expandable graphite in an amount of 0.1% by weight or more and less than 10% by weight relative to the total weight of the composition, (e) an inorganic filler selected from the group consisting of MgO, CaO, BaO, K₂O, Li₂O, Na₂O, and mixtures thereof, (a) The epoxy compound comprises a reactive diluent comprising at least one epoxy moiety and at least one linear or branched alkyl group, A thermosetting structural adhesive film for bonding to oily metal substrate surfaces.

2. A thermosetting structural adhesive film according to claim 1, for use in white body processes.

3. The thermosetting structural adhesive film according to claim 1 or 2, wherein the thermally expandable graphite particles have an aspect ratio of at least 1:2.

5.

4. The thermosetting structural adhesive film according to any one of claims 1 to 3, wherein the composition contains the thermally expandable graphite particles (d) in an amount of 0.5 to 7% by weight relative to the total weight of the composition.

5. A thermosetting structural adhesive film according to any one of claims 1 to 4, wherein the film exhibits overlap shear strengths according to DIN EN 1465 of at least 21 MPa at -40°C and / or at least 17 MPa at 23°C and / or at least 11 MPa at 80°C, and / or a T-type peel strength of at least 165 N according to ASTM D1876, and / or a reduction in overlap shear strength according to DIN EN 1465 of 30% or less after wet conditions, wherein the wet conditions are those in which the test specimen is wrapped in water-soaked cotton wool, then airtightly sealed in a polyethylene bag and stored at 70°C and 100% relative humidity for 7 days, after which the wrapped specimen is opened, stored at 23°C for 2 hours, then stored at -28°C for 2 hours, and subsequently reconditioned in a standard atmosphere.

6. A thermosetting structural adhesive film according to any one of claims 1 to 5, which induces a cohesive failure mode in a T-type peel test according to ASTM D1876.

7. The thermosetting structural adhesive film according to any one of claims 1 to 6, wherein the non-spherical particles of the thermally expandable graphite have a spherical equivalent particle size distribution measured in accordance with ISO 8130-13:2001 that is in the range of 30 μm to 200 μm.

Images