Curable two-part adhesive composition

Abstract

The present invention relates to a curable two - part adhesive composition comprising: a first part comprising one or more cyanoacrylate monomers, one or more (meth)acrylate monomers, a peroxide compound, and optionally additives for controlling viscosity and rheology; and a second part comprising a non - reactive diluent and a transition metal catalyst, and optionally an electron - rich initiator for the cyanoacrylate. It also relates to a syringe or cartridge comprising the two - part curable composition, to the use of such a composition for bonding substrates, to the use of such a composition for filling depressions, cracks or holes in or between substrates, to a method of bonding substrates using the composition, and to a repair method of filling depressions, cracks or holes in or between substrates using the composition.

Description

BACKGROUND OF THE INVENTION

[0002] Cyanoacrylate (CA)-based adhesive compositions are well-known, for example, as instant glues or so-called "super glues". They are popular in many application areas and are used by consumers, professional craftsmen, and industrial assemblers. They are solvent-free, 100% reactive materials, known for their ability to rapidly form strong bond joints on many different substrates and without the need for high-energy stimuli (such as electromagnetic radiation or heat) to initiate adhesive curing. From the perspective of sustainability and end-user convenience, these properties are very attractive.

[0003] In the assembly process of most substrate types, the ability of conventional one-component (1K) CA to cure or polymerize is partly related to the fact that, under normal conditions, the initiation of the polymerization process occurs from nucleophilic or ionic species present on most surfaces, such as adsorbed water, salts, trace amounts of basic materials, and so on. When the components to be assembled from substrates (such as metals, alloys, ceramics, rubbers, papers, living tissues, leathers, and plastics, etc.) are placed in contact with a thin layer of liquid cyanoacrylate adhesive therebetween, a very strong joint is produced when the adhesive cures into a solid.

[0004] Although the breadth of substrate types to which CA can rapidly bond at room temperature far exceeds any other adhesive category, certain substrates present challenges, such as so-called "low surface energy" substrates, such as polyolefins and "non-stick" fluoropolymers. Technical solutions proposed to address this limitation have been disclosed in the prior art, such as, for example, US 3,260,637, US 3,836,377, US 4,460,758, US 5,818,325, US 5,110,392, US 5,066,743, US 6,001,213, US-A-2003 / 0191248 or US-A-2005 / 0000646, in which the use of an activator is proposed prior to the subsequent application of the CA composition.

[0005] However, one obstacle associated with 1K adhesives involves the lack of so-called "complete volume cure" (CTV). This limited cure throughout the bulk of the adhesive occurs in thicker adhesive layers because the most effective cure occurs closest to the source of the initiator species, which is present on the surface.

[0006] When using CA adhesives, an alternative and more effective way to achieve CTV between the assembled substrates is to avoid methods that rely solely on the substrate surfaces as the source of effective initiators. Such methods instead rely on directly mixing a specific activator contained in a liquid or gel-like carrier into the bulk-reactive CA composition, where the mixture of these two separate compositions is then applied to the substrates. When the activator is at an appropriate concentration in a compatible carrier, this method allows for excellent distribution of the activator into the adhesive body relative to activation solely by the respective substrate interfaces. In this regard, mixing the components into the bulk adhesive is referred to as the "two-part", "two-component", or "2K" method, and methods involving CA compositions of this type are well known in the prior art.

[0007] Another drawback of CA adhesives is their limited durability, since in their common commercial forms, they consist mainly of a single monofunctional monomer that cures into linear polymer chains.

[0008] When describing the 2K method, the separate components or parts of the adhesive and / or its packaging are typically referred to as, for example, "Part A" and "Part B". Thus, if Part A contains the CA composition in one compartment or reservoir, Part B can contain a composition selected to activate the adhesive, cause the adhesive to react, and / or alter the physical properties of the adhesive (plasticize, color, toughen, etc.), the adhesive being produced by mixing the two parts by any method.

[0009] While there are obvious advantages to directly and uniformly mixing the active components into the CA composition in order to achieve simultaneous initiation throughout the adhesive mass and thus solve the CTV problem, the basic properties of the cured adhesive still depend only on those of the linearly polymerized monofunctional CA homopolymer, as in the case of 1K CA adhesives, except that now, as disclosed, for example, in US-A-201 I / 0196091, there is improved CTV, or, as disclosed, for example, in US-A-2017 / 0335151, there is CTV and toughness. While sufficient for many purposes and now addressing some of the drawbacks, such polymers produce adhesives that still have limitations in terms of durability. Attempts to remedy this situation have involved using (meth)acrylic monomers or epoxy monomers in combination with CA in 2K embodiments, even though either of the two types of mixtures has a different preferred primary polymerization mechanism. CA preferably polymerizes at room temperature (RT) via electron-rich initiators such as nucleophiles, basic materials, especially secondary or tertiary amines, phosphines, and hard anions or zwitterions, while acrylic monomers preferably polymerize via redox radical initiation at RT, and certain epoxides preferentially undergo cationic polymerization at RT. However, the 2K method can be explained as obtaining some performance gains from the interpenetrating network (IPN) of the separately polymerized monomers in the mixture, or even, in the case of acrylics, from certain copolymerizations, since CA can also participate in free radical polymerization, even though it is not the preferred mechanism. Such methods are described in the prior art, for acrylic 2K mixtures in, for example, WO-A-2013 / 111036, WO-A-2020 / 081750, WO-A-2020 / 082060, and for epoxy 2K mixtures in, for example, US 8,981,027.

[0010] However, in all these cases, the performance gains compromise the attractive feature of the fast bond speed of the parent CA, such that any enhancement in durability is accompanied by a sacrifice in bond speed.

[0011] Accordingly, there remains a need to provide an adhesive that retains the speed and multi-substrate bonding properties of CA itself (now also having CTV), while still further exhibiting significantly enhanced durability, especially for indoor and outdoor household applications.

[0012] Subject matter of the invention

[0013] The subject matter of the present invention is a two-part curable composition.

[0014] Another aspect of the present invention relates to a syringe or cartridge containing the two-part curable composition.

[0015] Another aspect of the present invention relates to the use of such compositions for bonding substrates.

[0016] Another aspect of the present invention relates to the use of such compositions for filling depressions, cracks or holes in or between substrates.

[0017] Another aspect of the present invention is a method of bonding substrates using the composition.

[0018] Another aspect of the present invention is a repair method of using the composition to fill depressions, cracks or holes in or between substrates. DETAILED DESCRIPTION OF THE INVENTION

[0020] The object of the present invention is a two - part curable composition, which comprises:

[0021] a) A first part (Part A), which comprises:

[0022] i. At least 50 wt.% of one or more cyanoacrylate monomers,

[0023] ii. At least 1 wt.% of one or more (meth)acrylic monomers, and

[0024] iii. At least 1 wt.% of a per - compound,

[0025] wherein wt.% is based on the total weight of the first part of the composition,

[0026] b) A second part (Part B), which comprises:

[0027] i. At least 50 wt.% of a non - reactive diluent, and

[0028] ii. 0.001 wt.% to 2 wt.% of a transition metal catalyst, expressed as the content of the transition metal,

[0029] wherein wt.% is based on the total weight of the second part of the composition,

[0030] wherein the volume ratio between the first part and the second part is in the range of 4:1 to 10:1,

[0031] provided that the second part does not contain any vinylic monomers.

[0032] The inventors of the present invention have developed a two - part curable composition which surprisingly combines speed and multi - substrate bonding, complete volume cure (CTV), while still further exhibiting significantly enhanced durability, especially for indoor and outdoor household applications.

[0033] Throughout this specification and the claims, a singular expression preceded by the article "a" or "the" is understood to also include a reference to the plural in a broad sense, unless the context clearly dictates otherwise.

[0034] In the context of the present invention, it is to be understood that the term "about" in relation to a determined value means an acceptable variation of the stated value, typically + / - 5%.

[0035] The ranges disclosed in this specification include both their lower and upper limits.

[0036] The term "working life" or "working time" ("WT") as used throughout this specification refers to the period between first mixing the activator into the cyanoacrylate composition and subsequently applying the activated composition to a component, i.e., the time the activated product resides or remains on the static mixing element (which is used to mix the adhesive components and serves as a dispensing nozzle) itself, i.e., the time between dispensing operations. Once the activator is mixed, the curing process begins and continues as the adhesive is dispensed from the static mixing element.

[0037] The term "open time" ("OT") refers to the time during which an activated and subsequently dispensed adhesive remains processable (i.e., does not cure significantly to the extent that it cannot form an effective bond when applied to a second substrate in the form of droplets, beads, or masses). The open time thus describes the period during which the adhesive remains activated but substantially uncured and ready to usefully bond components. An adhesive with a long OT is one that does not cure prematurely before assembling components even if it remains on a single component for a relatively long time.

[0038] The term "fixing time" ("FT") as used in this specification is a measure of the bonding speed and is defined as the time it takes for a bonded assembly using a minimum amount of adhesive (a "small" drop) on two mating substrates to be able to suspend a 3 kg weight for more than 10 s when a weight is hung vertically at one end of the bonded assembly.

[0039] The first part of the composition - Part A

[0040] Cyanoacrylate monomer

[0041] The first part of the composition contains at least 50 wt.% of one or more cyanoacrylate monomers.

[0042] In the context of the present invention, the term cyanoacrylate includes cyanoacrylate monomers which, in a preferred embodiment, may be represented by the general formula (I):

[0043]

[0044] wherein R is selected from C1-C 18 a straight-chain or branched alkyl chain, C3-C 20 alkoxyalkyl, trimethylsilylated C1-C3 alkyl chain, furfuryl, allyl, cyclohexyl and a group having the following formula: -R i -O-C(O)-C(R j )=CH2, wherein R i is an organic moiety (preferably an alkylene), and R j is H or CH3.

[0045] In one embodiment, the cyanoacrylate monomer is an alkoxyalkyl cyanoacrylate defined by the general formula (I), wherein R is defined by the general formula (II):

[0046]

[0047] wherein R1 = CH3 or H, and R2 = a C1-C4 straight-chain or branched alkyl, and m ranges from 1 to 3.

[0048] The cyanoacrylate monomer can be selected from 2-methoxyethyl cyanoacrylate, 2-ethoxyethyl cyanoacrylate, 2-(1-methoxy)propyl cyanoacrylate, n-propyl cyanoacrylate, ethyl 2-cyanoacrylate, isopropyl cyanoacrylate, n-butyl cyanoacrylate, sec-butyl cyanoacrylate, isobutyl cyanoacrylate, tert-butyl cyanoacrylate, n-pentyl cyanoacrylate, 1-methylbutyl cyanoacrylate, 1-ethylpropyl cyanoacrylate, neopentyl cyanoacrylate, n-hexyl cyanoacrylate, 1-methylpentyl cyanoacrylate, n-heptyl cyanoacrylate, n-octyl cyanoacrylate, n-nonyl cyanoacrylate, n-decyl cyanoacrylate, n-undecyl cyanoacrylate, n-dodecyl cyanoacrylate, cyclohexyl cyanoacrylate, 2-(2'-methoxy)-ethoxyethyl-2"-cyanoacrylate, 2-(2'-ethoxy)-ethoxyethyl-2"-cyanoacrylate, 2-(2'-propoxy)-ethoxyethyl-2"-cyanoacrylate, 2-(2'-butoxy)-ethoxyethyl-2"-cyanoacrylate, 2-(2'-pentoxy)-ethoxyethyl-2"-cyanoacrylate, 2-(2'-hexoxy)-ethoxyethyl-2"-cyanoacrylate, 2-(2'-methoxy)-propoxypropyl-2"-cyanoacrylate, 2-(2'-ethoxy)-propoxypropyl-2"-cyanoacrylate, 2-(2'-propoxy)-propoxypropyl-2"-cyanoacrylate, 2-(2'-butoxy)-propoxypropyl-2"-cyanoacrylate, 2-(2'-pentoxy)-propoxypropyl-2"-cyanoacrylate, 2-(2'-hexoxy)-propoxypropyl-2"-cyanoacrylate, 2-(2'-methoxy)-butoxybutyl-2"-cyanoacrylate, 2-(2'-ethoxy)-butoxybutyl-2"-cyanoacrylate, 2-(2'-butoxy)-butoxybutyl-2"-cyanoacrylate, 2-(3'-methoxy)-propoxyethyl-2"-cyanoacrylate, 2-(3'-methoxy)-butoxyethyl-2"-cyanoacrylate, 2-(3'-methoxy)-propoxypropyl-2"-cyanoacrylate, 2-(3'-methoxy)-butoxypropyl-2"-cyanoacrylate, 2-(2'-methoxy)-ethoxypropyl-2"-cyanoacrylate, 2-(2'-methoxy)-ethoxybutyl-2"-cyanoacrylate, and mixtures thereof.

[0049] Preferably, the cyanoacrylate monomer is selected from ethyl 2-cyanoacrylate, 2-methoxyethyl cyanoacrylate, and mixtures thereof.

[0050] A combination of one or more such cyanoacrylates can be used.

[0051] The monomers of such structures (I) can be prepared by methods known to those skilled in the art, such as, for example, the methods described in US 2,467,927. Some of them, such as ethyl cyanoacrylate (ECA) and 2-methoxyethyl cyanoacrylate (MECA), are commercially available.

[0052] In the first part of the composition of the present invention, based on the total weight of the first part, the total content of the cyanoacrylate monomer can be higher than 50 wt.%, preferably higher than or equal to 70 wt.%, and more particularly higher than or equal to 80 wt.%.

[0053] In one embodiment, in the first part of the composition of the present invention, based on the total weight of the first part of the composition, the total content of the cyanoacrylate monomer is in the range of 50 wt.% to 99 wt.%, preferably 70 wt.% to 97 wt.%, and more preferably 85 wt.% to 95 wt.%.

[0054] (Meth)acrylic monomer

[0055] The first part of the composition contains at least 1 wt.% of one or more (meth)acrylic monomers.

[0056] In the context of the present invention, the (meth)acrylic monomers of part A of the two-part curable composition can be selected from: - compounds of the general formula (iii)

[0057] CH2=CR3(CO2R4) (III)

[0058] wherein R3 represents methyl or H (preferably H), and R4 is a hydrogen atom, a C1-C8 straight-chain or branched-chain alkyl group, a C2-C6 straight-chain or branched-chain alkoxyalkyl group, a furfuryl group, or an isobornyl group;

[0059] - polyfunctional (meth)acrylates, such as, for example: butanediol di(meth)acrylate, hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, triethyleneglycol dimethacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane tri(meth)acrylate (TMPTA), ethoxylated trimethylolpropane tri(meth)acrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate (PETA), pentaerythritol tetramethacrylate (PETMA), dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, bisphenol A diacrylate, bisphenol A dimethacrylate, ethoxylated bisphenol A diacrylate, propoxylated bisphenol A diacrylate, and mixtures thereof, and - mixtures thereof.

[0060] In a preferred embodiment, the (meth)acrylic monomer of formula (III) is selected from methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate.

[0061] The (meth)acrylic monomer of formula (III) is commercially available from well-known suppliers such as, for example, Sartomer, Arkema or BASF.

[0062] A polyfunctional (meth)acrylate is a (meth)acrylate having more than one functionality, for example an additional (meth)acrylate. The polyfunctional (meth)acrylate may be an ester derived from (meth)acrylic acid and a diol or polyol such as butanediol, hexanediol, diethylene glycol, triethylene glycol, polyethylene glycol, trimethylolpropane, neopentyl glycol, pentaerythritol, bisphenol A or an alkoxylated derivative thereof.

[0063] The polyfunctional (meth)acrylate may also have a relatively low molecular weight, such as commercially available triethylene glycol dimethacrylate or butanediol dimethacrylate, or may have a relatively high molecular weight: (meth)acrylic acid-functionalized oligomers and (meth)acrylic acid-functionalized resins such as (meth)acrylate-capped polymers such as (meth)acrylate-capped urethane polymers or copolymers, or so-called (meth)acrylate-functionalized telechelic, dendritic or hyperbranched materials. Examples of such may be obtained, for example, from Sartomer under the trade names CN1993CG, CN2608, CN9210, CN2300 and CN2301.

[0064] Preferred polyfunctional (meth)acrylates are tricyclodecane dimethanol diacrylate (commercially available as Sartomer SR833S), ethoxylated trimethylolpropane triacrylate (commercially available as Sartomer SR454); 1,4-butanediol dimethacrylate and tris(2-hydroxyethyl) isocyanurate triacrylate.

[0065] Examples of (meth)acrylic monomers can be readily obtained from well-known suppliers such as, for example, Sartomer, Arkema and BASF.

[0066] The (meth)acrylic monomer of part A of the two-part curable composition may be selected from:

[0067] - a compound of general formula (III)

[0068] CH2=CR3(CO2R4) (III)

[0069] wherein R3 represents methyl or H (preferably H), and R4 is a hydrogen atom, a C1-C8 straight or branched alkyl group, a C2-C6 straight or branched alkoxyalkyl group, a furfuryl group, or an isobornyl group;

[0070] - polyfunctional (meth)acrylates, such as, for example: butanediol di(meth)acrylate, hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, triethyleneglycol dimethacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane tri(meth)acrylate (TMPTA), ethoxylated trimethylolpropane tri(meth)acrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate (PETA), pentaerythritol tetramethacrylate (PETMA), dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, bisphenol A diacrylate, bisphenol A dimethacrylate, ethoxylated bisphenol A diacrylate, propoxylated bisphenol A diacrylate, and mixtures thereof; (meth)acrylate-functionalized oligomers and (meth)acrylate-functionalized resins, such as, for example, (meth)acrylate-capped polymers, such as (meth)acrylate-capped urethane polymers or copolymers, or so-called (meth)acrylate-functionalized telechelic, dendritic, or hyperbranched materials; and

[0071] - mixtures thereof.

[0072] In the first part of the composition of the present invention, based on the total weight of the first part of the composition, the total content of (meth)acrylate monomers is at least 1 wt.%, preferably at least 2 wt.%, more preferably at least 3 wt.%. In a preferred embodiment, based on the total weight of the first part of the composition, the total content of (meth)acrylate monomers constitutes 1 wt.% to 10 wt.%, preferably 2 wt.% to 6 wt.%.

[0073] Peroxide compound

[0074] The first part of the composition contains a peroxy compound.

[0075] A peroxy compound is a compound containing a group O-O in its structure. In the context of the present invention, peroxy compounds are selected from peresters, perborates, persulfates, peracetals, or peroxides.

[0076] Suitable peroxy compounds are, for example, tert-butyl perbenzoate (TBPB) or tert-butyl peroxide (TBP).

[0077] Peroxy compounds are commercially available, for example, from Acros Organics or Sigma-Aldrich.

[0078] Based on the total weight of the first part of the composition, the total content of the peroxide compound is at least 1 wt.%, preferably it constitutes 1 wt.% to 10 wt.%, preferably 2 wt.% to 8 wt.%, and more preferably 3 wt.% to 7 wt.%.

[0079] Additive

[0080] The first part of the composition may further contain one or more additives. The additives are selected from, for example, stabilizers, tackifiers, accelerators, thixotropic agents, thickeners, toughening agents, plasticizers, antioxidants, pigments, colorants, and mixtures thereof.

[0081] In a preferred embodiment, the first part of the composition further comprises a combination of a stabilizer, a thixotropic agent, and a thickener.

[0082] Stabilizer

[0083] The first part of the composition of the present invention (including the cyanoacrylate monomer) preferably contains one or more stabilizers, which are selected from free radical stabilizers, acid stabilizers, and mixtures thereof. In a preferred embodiment, the first part of the composition contains one or more stabilizers, and in a more preferred embodiment, the first part of the composition contains a combination of a free radical stabilizer and an acid stabilizer.

[0084] The free radical stabilizer is a free radical polymerization inhibitor and is preferably selected from 4-methoxyphenol, hydroquinone, hydroquinone monomethyl ether, hydroxytoluene butyl ether, butylated hydroxyanisole, 4,4'-methylenebis(2,6-di-tert-butylphenol), and mixtures thereof.

[0085] The acid stabilizer is an inhibitor of anionic polymerization and may be selected from Bronsted acids, Lewis acids, and mixtures thereof. The acid stabilizer is preferably selected from methanesulfonic acid, p-toluenesulfonic acid, hydrofluoric acid, boron trifluoride, boron trifluoride diethyl ether complex, fluoroboric acid, sulfur dioxide, and mixtures thereof.

[0086] In a preferred embodiment, as the stabilizer, the first part of the composition contains a combination of methanesulfonic acid, sulfur dioxide, boron trifluoride diethyl ether complex, hydroquinone, hydroquinone monomethyl ether, and 4,4'-methylenebis(2,6-di-tert-butylphenol).

[0087] Based on the total weight of the first part of the composition, the content of the free radical stabilizer in the first part of the composition can be in the range of 0.001 wt.% to 0.2 wt.%, preferably 0.01 wt.% to 0.1 wt.%, and more preferably 0.02 wt.% to 0.06 wt.%.

[0088] In the first part of the composition of the present invention, the content of the acid stabilizer is generally in the range of 0.0003 wt.% to 0.1 wt.%, preferably 0.001 wt.% to 0.05 wt.%, and more preferably 0.0015 wt.% to 0.02 wt.%.

[0089] Adhesive promoter

[0090] Generally, the adhesive promoter can be selected from aromatic carboxylic acids or acid anhydrides, and is preferably selected from trimellitic acid, trimellitic anhydride, cis-1,2,3,6-tetrahydrophthalic anhydride, pyromellitic acid, pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, itaconic acid, itaconic anhydride, 3-butene-1,2,3-tricarboxylic acid, and mixtures thereof.

[0091] Based on the total weight of the first part of the composition, the total content of the adhesive promoter in the first part of the composition can be in the range of 0.02 wt.% to 0.1 wt.%, more preferably 0.03 wt.% to 0.08 wt.%.

[0092] Accelerator

[0093] The accelerator (accelerating agent or accelerator) suitable for the first part of the composition is crown ether (such as 15-crown-5, 18-crown-6, dibenzo-18-crown-6, Alfa Aesar Co), cyclodextrin, calixarene, and mixtures thereof. The preferred accelerator is dibenzo-18-crown-6.

[0094] Generally, based on the total weight of the first part of the composition, the content of the accelerator in the first part of the composition is in the range of 0.01 wt.% to 0.8 wt.%, preferably 0.05 wt.% to 0.5 wt.%, and more preferably 0.1 wt.% to 0.3 wt.%.

[0095] Thixotropic agent

[0096] The thixotropic agent suitable for the first part of the composition can be selected from hydrogenated castor oil, hydrogenated castor oil modified by reaction with an amine, polyamide, silica, and mixtures thereof.

[0097] Preferably, the thixotropic agent is silica, and it can be selected from fumed silica, hydrophobic fumed silica, hydrophilic fumed silica, and precipitated silica. In a more preferred embodiment, it is hydrophobized fumed silica (such as R202, Evonik).

[0098] Generally, based on the total weight of the first part of the composition, the total content of the thixotropic agent in the first part of the composition can be in the range of 2 wt.% to 10 wt.%, preferably 3 wt.% to 8 wt.%, and more preferably 4 wt.% to 7 wt.%.

[0099] Thickening agent

[0100] The thickener (thickener or thickening agent) suitable for the first part of the composition can be selected from those compatible with the main monomers contained therein. Examples of such thickeners include poly(meth)acrylates, acylated cellulose polymers (such as cellulose acetate), polyvinyl acetate, partially hydrolyzed polyvinyl acetate, polyvinylpyrrolidone, polyoxylates, polycaprolactones, polycyanoacrylates, vinyl acetate copolymers (such as copolymers with vinyl chloride), copolymers of (meth)acrylates with butadiene and styrene, copolymers of vinyl chloride and acrylonitrile, copolymers of ethylene and vinyl acetate, poly(butylene terephthalate-co-ethylene glycol terephthalate), copolymers of lactic acid and caprolactone, and mixtures thereof.

[0101] These thickeners are well-known to those skilled in the art and have been described in the prior art.

[0102] Preferably, in the composition of the present invention, the thickener is selected from poly(meth)acrylates, polyvinylpyrrolidone, polyvinyl acetate, partially hydrolyzed polyvinyl acetate, vinyl acetate copolymers, and acylated cellulose polymers. The thickener suitable for the first part of the composition can be, for example, polymethyl methacrylate (such as M 449, Evonik), copolymer of vinyl acetate and vinyl alcohol (such as 900, Lanxess), copolymer of vinyl chloride and vinyl acetate (such as H 40-60, Wacker), copolymer of ethylene, vinyl acetate and an ester or partial ester of maleic acid (such as G, DuPont), and mixtures thereof.

[0103] Generally, based on the total weight of the first part of the composition, the content of the thickener in the first part of the composition is in the range of 2 wt.% to 10 wt.%, preferably 3 wt.% to 8 wt.%, and more preferably 4 wt.% to 7 wt.%.

[0104] Toughening agent

[0105] The toughener (toughening agent) suitable for the first part of the composition is a block copolymer, such as, for example, poly(methyl methacrylate-co-butyl acrylate-co-methyl methacrylate), commercially available as Kurarity LA2140; an elastomeric rubber; an elastomeric polymer; a liquid elastomer; a polyester; an acrylic rubber; a butadiene / acrylonitrile rubber; a buna rubber; a polyisobutylene; a polyisoprene; a natural rubber; a synthetic rubber, such as styrene / butadiene rubber (SBR); a polyurethane polymer; an ethylene-vinyl acetate polymer; a fluorinated rubber; an isoprene-acrylonitrile polymer; a chlorosulfonated polyethylene; a homopolymer of polyvinyl acetate; a block copolymer; a core-shell rubber particle; and mixtures thereof.

[0106] Generally, based on the total weight of the first part of the composition, the content of the toughener in the first part of the composition is in the range of 2 wt.% to 15 wt.%, preferably 3 wt.% to 8 wt.%, and more preferably 4 wt.% to 7 wt.%.

[0107] Plasticizer

[0108] Suitable plasticizers include phthalates, azelates, adipates, alkyl sebacates, acetates (such as triacetin) and non-reactive esters (such as propan-1,2,3-triyl triheptanoate). Preferred plasticizers are triacetin, triethyl acetylcitrate and propan-1,2,3-triyl triheptanoate. Preferably, the plasticizer is not included in the first part of the composition.

[0109] Antioxidant

[0110] The antioxidant suitable for the first part of the composition can especially be methylene bis(4-methyl-6-tert-butylphenol) and butylated hydroxyanisole, 4-methyl-2,6-di-tert-butylphenol, hydroquinone monomethyl ether, tert-butylhydroquinone, and mixtures thereof.

[0111] Generally, the content of the antioxidant in the first part of the composition constitutes 0.01 wt.% to 0.8 wt.%, preferably 0.05 wt.% to 0.5 wt.%, and more preferably 0.1 wt.% to 0.3 wt.%.

[0112] The second part of the composition - Part B

[0113] The second part of the composition does not contain any ethylenic monomers.

[0114] Non-reactive diluent

[0115] The second part of the composition contains a non-reactive diluent. The non-reactive diluent can be, for example, a plasticizer. In the context of the present invention, the non-reactive diluent is a plasticizer selected from phthalates, citrates, azelates, adipates, sebacates, acetates (such as triacetin) and non-reactive esters (such as tripropyl heptane-1,2,3-tricarboxylate).

[0116] Preferred plasticizers are triacetin, triethyl acetyl citrate and tripropyl heptane-1,2,3-tricarboxylate.

[0117] Generally, based on the total weight of the second part of the composition, the total content of the non-reactive diluent in the second part of the composition is at least 50 wt.%. Based on the total weight of the second part of the composition, it can be in the range of 50 wt.% to 99.9 wt.%, preferably 60 wt.% to 90 wt.%, and more preferably 70 wt.% to 85 wt.%.

[0118] Transition metal catalyst

[0119] The second part of the composition contains 0.001 wt.% to 2 wt.% of a transition metal catalyst, expressed as the content of the transition metal.

[0120] The transition metal catalyst is mixed with the per-compound contained in the first part of the composition to generate free radicals.

[0121] Many salts of transition metals are known to participate in so-called redox radical initiation systems, as described in Garra et al., Prog. Pol. Sci., 2019, 94, 33, for example salts derived from Cu(II), Cu(I), Fe(III), Fe(II), Mn(II), Mn(III), Mn(IV), Ag(I), Rh(I), Rh(II), Co(II), V(III), V(IV), V(V), Cr(VI), Ti(III), Pt and Pd.

[0122] The transition metal catalyst in the present invention is preferably a transition metal salt. In the context of the present invention, the term "transition metal salt" is a compound composed of a collection of cations and anions of transition metals, where the bond between the transition metal salt and the anion can have characteristics ranging from ionic to covalent, and also includes its hydrates and solvates. In a preferred embodiment, the transition metal salt is selected from Cu(ACN)4BF4, Cu(ACN)4PF6, Cu(BF4)2, copper(II) acetate, copper(II) octanoate, copper(II) benzoate, copper(II) chlorate, copper(II) carbonate, copper(II) acetylacetonate, copper(I) trifluoromethanesulfonate, copper(II) sulfate, iron(II) trifluoromethanesulfonate, ferrocene, iron(II) tetrafluoroborate, MnClO4, cobalt naphthenate, cobalt tetrafluoroborate. The most preferred transition metal salt is Cu(BF4)2 and its hydrates and solvates.

[0123] The transition metal salt can be soluble or stably suspended in a non-reactive diluent. The inclusion of a thickener, thixotropic agent, or inorganic filler can help obtain a stable suspension of the transition metal salt in the non-reactive diluent.

[0124] Based on the total weight of the second part of the composition, the content of the transition metal catalyst in the second part of the composition (expressed as the content of the transition metal) is preferably in the range of 0.005 wt.% to 0.5 wt.%, and more preferably 0.01 wt.% to 0.03 wt.%.

[0125] In the case of using a specific transition metal salt, a person skilled in the art can calculate the corresponding amount of the salt to have a specific amount of the transition metal catalyst. For example, 0.02 wt.% of Cu(I) as the transition metal catalyst corresponds to 0.10 wt.% of the transition metal salt Cu(ACN)4BF4, or 0.117 wt.% of Cu(ACN)4PF6.

[0126] Based on the total weight of the final two-part mixture, the typical concentration of the transition metal catalyst in the final two-part mixture is in the range of 0.0001 wt.% to 0.2 wt.%, preferably 0.0005 wt.% to 0.1 wt.%, more preferably 0.0007 wt.% to 0.08 wt.%, and even more preferably 0.001 wt.% to 0.05 wt.%.

[0127] Electron-rich initiators

[0128] The second part of the composition optionally contains electron-rich initiator classes for cyanoacrylate.

[0129] In an embodiment, the second part of the composition contains electron-rich initiator classes for cyanoacrylate.

[0130] The electron-rich initiator can be selected from organic bases, salts with hard anions, reactive inorganic fillers, calcium, zinc, and magnesium salts with organic counter anions (provided that they do not contain an ethylenic moiety), and mixtures thereof.

[0131] Suitable organic bases are, for example, caffeine, theobromine, 5-chloro-2-methylbenzothiazole, and tetrahydroquinoline.

[0132] Suitable salts with hard anions are, for example, choline chloride and benzalkonium chloride.

[0133] Suitable reactive inorganic fillers are, for example, those called calcium silicate hydrate D.

[0134] Suitable calcium, zinc, and magnesium salts with organic counter anions (provided that they do not contain an ethylenic moiety) are, for example, calcium stearate.

[0135] The preferred reactive inorganic filler is D. This compound is a calcium silicate hydrate with the chemical structure of tobermorite (Ca6Si6O 17 (OH)2), the particles of which are substantially spherical and microporous. The product has an apparent density between 85 g / l and 130 g / l, an average particle size between 35 and 65 microns, and it has a CAS registration number of 1344-95-2.

[0136] In a preferred embodiment, based on the total weight of the second part of the composition, the content of the electron-rich initiator in the second part of the composition constitutes 0.05 wt.% to 3 wt.%, preferably 0.1 wt.% to 2 wt.%, more preferably 0.5 wt.% to 1.2 wt.%.

[0137] Additive

[0138] The second part of the composition may further contain one or more additives. Additives are, for example, selected from thixotropic agents, thickeners, toughening agents, accelerators, tackifiers, pigments, colorants, and mixtures thereof.

[0139] Thixotropic agent

[0140] Suitable and preferred thixotropic agents for the second part of the composition can be selected from the group disclosed for the thixotropic agent of the first part of the composition.

[0141] Generally, based on the total weight of the second part of the composition, the total content of the thixotropic agent in the second part of the composition can be in the range of 2 wt.% to 10 wt.%, preferably 3 wt.% to 8 wt.%, and more preferably 4 wt.% to 7 wt.%. In a preferred embodiment, based on the total weight of the second part of the composition, the content is in the range of 2 wt.% to 8 wt.%.

[0142] Thickener

[0143] Suitable and preferred thickeners for the second part of the composition may be selected from the group disclosed for the thickeners of the first part of the composition.

[0144] Generally, based on the total weight of the second part of the composition, the content of the thickener in the second part of the composition is in the range of 2 wt.% to 20 wt.%, preferably 3 wt.% to 15 wt.%, and more preferably 4 wt.% to 13 wt.%. In a preferred embodiment, based on the total weight of the second part of the composition, the content is in the range of 2 wt.% to 15 wt.%.

[0145] Toughening agent

[0146] Toughening agents suitable for the second part of the composition may be selected from the group disclosed for the toughening agents of the first part of the composition.

[0147] Generally, based on the total weight of the second part of the composition, the content of the toughening agent in the second part of the composition is in the range of 2 wt.% to 15 wt.%, preferably 3 wt.% to 8 wt.%, and more preferably 4 wt.% to 7 wt.%.

[0148] Accelerator

[0149] Accelerators suitable for the second part of the composition may be selected from the group disclosed for the accelerators of the first part of the composition. A preferred accelerator is dibenzo-18-crown-6.

[0150] Generally, based on the total weight of the first part of the composition, the content of the accelerator in the first part of the composition is in the range of 0.01 wt.% to 0.8 wt.%, preferably 0.05 wt.% to 0.5 wt.%, and more preferably 0.1 wt.% to 0.3 wt.%.

[0151] Adhesion promoter

[0152] Adhesion promoters suitable for the second part of the composition may be selected from the group disclosed for the adhesion promoters of the first part of the composition.

[0153] Based on the total weight of the second part of the composition, if present, the total content of the adhesion promoter in the second part of the composition may be in the range of 0.01 wt.% to 0.1 wt.%, more preferably 0.01 wt.% to 0.08 wt.%.

[0154] Curable composition

[0155] The two-part curable composition may be dispensed from a package (e.g., a two-part syringe) or from a reservoir. The former is generally convenient for manual application.

[0156] The volume ratio of the first part to the second part is in the range of 4:1 to 10:1, and more preferably 10:1.

[0157] In a preferred embodiment, the two - part curable composition comprises:

[0158] a) A first part (Part A), which comprises:

[0159] i. 50 wt.% to 99 wt.%, preferably 70 wt.% to 97 wt.%, and more preferably 85 wt.% to 95 wt.% of one or more cyanoacrylate monomers,

[0160] ii. At least 1 wt.% of one or more (meth)acrylic monomers, and

[0161] iii. At least 1 wt.% of a peroxide compound,

[0162] wherein wt.% is based on the total weight of the first part of the composition,

[0163] b) A second part (Part B), which comprises:

[0164] i. 50 wt.% to 99.9 wt.%, preferably 60 wt.% to 90 wt.%, and more preferably 70 wt.% to 85 wt.% of a non - reactive diluent, and

[0165] ii. 0.001 wt.% to 2 wt.%, preferably 0.005 wt.% to 0.5 wt.%, and more preferably 0.01 wt.% to 0.03 wt.% of a transition metal catalyst, expressed as the content of the transition metal,

[0166] wherein wt.% is based on the total weight of the second part of the composition,

[0167] wherein the volume ratio between the first part and the second part is in the range of 4:1 to 10:1, preferably 10:1,

[0168] provided that the second part does not contain any vinyl monomer.

[0169] In a preferred embodiment, the two - part curable composition comprises:

[0170] a) A first part (Part A), which comprises:

[0171] i. At least 50 wt.%, preferably 50 wt.% to 99.9 wt.%, preferably 60 wt.% to 90 wt.%, and more preferably 70 wt.% to 85 wt.% of one or more cyanoacrylate monomers;

[0172] ii. 1 wt.% to 10 wt.% of one or more (meth)acrylate monomers;

[0173] iii. 1 wt.% to 10 wt.% of a peroxide compound;

[0174] iv. 0.001 wt.% to 0.2 wt.% of a stabilizer;

[0175] v. 2 wt.% to 10 wt.% of a thixotropic agent by weight;

[0176] vi. 2 wt.% to 10 wt.% of a thickening agent by weight;

[0177] wherein wt.% is based on the total weight of the first part of the composition,

[0178] b) A second part (Part B), which comprises:

[0179] i. At least 50 wt.%, preferably 50 wt.% to 99.9 wt.%, more preferably 60 wt.% to 90 wt.%, and even more preferably 70 wt.% to 85 wt.% of at least one non-reactive diluent;

[0180] ii. 0.001 wt.% to 2 wt.%, preferably 0.005 wt.% to 0.5 wt.%, and more preferably 0.01 wt.% to 0.03 wt.% of a transition metal catalyst, expressed as the content of the transition metal, and

[0181] iii. 0.1 wt.% to 2 wt.% of an electron-rich initiator compound;

[0182] iv. 2 wt.% to 15 wt.% of a thickening agent;

[0183] v. 2 wt.% to 8 wt.% of a thixotropic agent;

[0184] wherein wt.% is based on the total weight of the second part of the composition,

[0185] wherein the volume ratio between the first part and the second part is in the range of 4:1 to 10:1, preferably 10:1,

[0186] provided that the second part does not contain any ethylenically unsaturated monomers.

[0187] Syringe or cartridge

[0188] In addition, part of the object of the present invention is a syringe or cartridge containing a two-part curable cyanoacrylate composition.

[0189] Preferably, the syringe or cartridge is a syringe or cartridge having two chambers, each of the two chambers having a different volume, one for a first portion of the composition and the other for a second portion of the composition.

[0190] Preferably, the syringe (or cartridge) is a syringe (correspondingly, cartridge) having two chambers, each of the two chambers having a different volume, one for the first portion of the composition as defined above and the other for the second portion of the composition as defined above.

[0191] The first portion of the composition is preferably placed in the chamber with the larger volume.

[0192] Preferably, the adhesive is prepared by manually or with the aid of a gun pressing on the plunger of the syringe or cartridge with a mixture of the two portions of the composition, which forces the contents of the chamber into a static mixer and thereby obtains the adhesive of the present invention at its outlet. In this adhesive, the two components are advantageously intimately mixed.

[0193] The preferred mixing ratio of part A: part B is in the range of 10:1 to 4:1, and the preferred static mixer must conform to the selected mixing ratio. Most preferably, the mixing ratio is 10:1.

[0194] Use of the composition

[0195] The use of the two - part curable composition of the present invention for bonding substrates also forms part of the subject matter of the present invention.

[0196] The method of bonding substrates also forms part of the subject matter of the present invention. The method of bonding substrates comprises the following steps:

[0197] 1) Mixing the two - part curable composition of the present invention together,

[0198] 2) Applying the mixture of step 1) to at least one substrate, and

[0199] 3) Bringing the substrates together for a time sufficient to allow a bond to form between the mated substrates.

[0200] The use of the two - part curable composition of the present invention for filling depressions, cracks or holes in or between substrates also forms part of the subject matter of the present invention.

[0201] The repair method of filling depressions, cracks or holes in or between substrates also forms part of the subject matter of the present invention. The repair method comprises the following steps:

[0202] 1) Mixing the two - part curable composition of the present invention together,

[0203] 2) Apply the mixture of step 1) into the depressions, cracks or holes of the substrate or on the upper part of the substrate, and optionally,

[0204] 3) Assemble a second substrate above the first substrate.

[0205] The two - part adhesive composition of the present invention advantageously exhibits at least one of the following properties:

[0206] A. Quick fixation on various substrate types, preferably less than 1 min, more preferably less than 35 s.

[0207] B. High bond strength with no - gap setting, meaning that using the no - gap tensile shear stress method, it is 10 - 25 MPa on a clean metal substrate measured 24 h after assembly.

[0208] C. High CTV level, meaning that as disclosed in WO - A - 2015 / 059644 (page 15, lines 5 - 13), using the tensile shear stress method with a 2 - mm gap, it is preferably 3 - 18 MPa on a clean mild steel substrate with a 2 - mm gap setting measured 24 h after assembly.

[0209] D. Hot - water immersion tolerance, measured by the bond strength of 3 - 10 MPa on a clean ABS substrate after immersion and continuous exposure to neutral water at 60 °C for 3 days.

[0210] E. Energy absorption, meaning that using the method disclosed in WO - A - 2015 / 059644 (page 15, lines 26 - 27 and page 23, lines 15 - 16), in a destructive tensile test, the integral area under the stress - strain curve of a mild steel substrate bonded with a 2 - mm gap setting is equal to or greater than 1 J.

[0211] F. Resistance to organic solvents, as exemplified by a high degree of insolubility between 35% and 100% in acetone at room temperature for 24 h.

[0212] G. Excellent shelf - life stability (12 - 24 months) compatible with the consumer market.

[0213] At least, the two - part adhesive composition of the present invention advantageously exhibits the following properties: A, C, F, and G.

[0214] Despite the prior art, no adhesive composition exhibits the above four characteristics. Surprisingly, the two - part adhesive composition of the present invention does meet all these characteristics, resulting in excellent durability of the final composition.

[0215] The present invention includes the following embodiments:

[0216] 1. A two - part curable composition, characterized in that it comprises:

[0217] a) A first part (Part A), which comprises:

[0218] i. At least 50 wt.% of one or more cyanoacrylate monomers,

[0219] ii. At least 1 wt.% of one or more (meth)acrylic monomers, and

[0220] iii. At least 1 wt.% of a peroxide compound,

[0221] wherein wt.% is based on the total weight of the first part of the composition,

[0222] b) A second part (Part B), which comprises:

[0223] i. At least 50 wt.% of a non - reactive diluent, and

[0224] ii. 0.001 wt.% to 2 wt.% of a transition - metal catalyst, expressed as the content of the transition metal,

[0225] wherein wt.% is based on the total weight of the second part of the composition,

[0226] wherein the volume ratio between the first part and the second part is in the range of 4:1 to 10:1,

[0227] provided that the second part does not contain any vinyl monomers.

[0228] 2. The two - part curable composition according to embodiment 1, characterized in that the cyanoacrylate monomer is represented by the general formula (I):

[0229]

[0230] wherein R is selected from C1 - C 18 linear or branched alkyl chains, C3 - C 20 alkoxyalkyl, trimethylsilylated C1 - C3 alkyl chains, furfuryl, allyl, cyclohexyl and groups having the formula: - R i - O - C(O)- C(R j ) = CH2, wherein R i is an organic moiety (preferably an alkylene), and R j is H or CH3.

[0231] 3. The two - part curable composition according to embodiment 2, characterized in that the cyanoacrylate monomer is an alkoxyalkyl cyanoacrylate defined by the general formula (I), wherein R is defined by the general formula (II):

[0232]

[0233] Wherein R1 = CH3 or H, and R2 = a C1-C4 straight-chain or branched-chain alkyl group, and m ranges from 1 to 3.

[0234] 4. The two-part curable composition according to embodiment 2, characterized in that the cyanoacrylate monomer is selected from 2-methoxyethyl cyanoacrylate, 2-ethoxyethyl cyanoacrylate, 2-(1-methoxy)propyl cyanoacrylate, n-propyl cyanoacrylate, ethyl 2-cyanoacrylate, isopropyl cyanoacrylate, n-butyl cyanoacrylate, sec-butyl cyanoacrylate, isobutyl cyanoacrylate, tert-butyl cyanoacrylate, n-pentyl cyanoacrylate, 1-methylbutyl cyanoacrylate, 1-ethylpropyl cyanoacrylate, neopentyl cyanoacrylate, n-hexyl cyanoacrylate, 1-methylpentyl cyanoacrylate, n-heptyl cyanoacrylate, n-octyl cyanoacrylate, n-nonyl cyanoacrylate, n-decyl cyanoacrylate, n-undecyl cyanoacrylate, n-dodecyl cyanoacrylate, cyclohexyl cyanoacrylate, 2-(2'-methoxy)-ethoxyethyl-2"-cyanoacrylate, 2-(2'-ethoxy)-ethoxyethyl-2″-cyanoacrylate, 2-(2'-propoxy)-ethoxyethyl-2″-cyanoacrylate, 2-(2'-butoxy)-ethoxyethyl-2″-cyanoacrylate, 2-(2'-pentoxy)-ethoxyethyl-2″-cyanoacrylate, 2-(2'-hexoxy)-ethoxyethyl-2″-cyanoacrylate, 2-(2'-methoxy)-propoxypropyl-2″-cyanoacrylate, 2-(2'-ethoxy)-propoxypropyl-2″-cyanoacrylate, 2-(2'-propoxy)-propoxypropyl-2″-cyanoacrylate, 2-(2'-butoxy)-propoxypropyl-2"-cyanoacrylate, 2-(2'-pentoxy)-propoxypropyl-2"-cyanoacrylate, 2-(2'-hexoxy)-propoxypropyl-2″-cyanoacrylate, 2-(2'-methoxy)-butoxybutyl-2″-cyanoacrylate, 2-(2'-ethoxy)-butoxybutyl-2″-cyanoacrylate, 2-(2'-butoxy)-butoxybutyl-2″-cyanoacrylate, 2-(3'-methoxy)-propoxyethyl-2″-cyanoacrylate, 2-(3'-methoxy)-butoxyethyl-2″-cyanoacrylate, 2-(3'-methoxy)-propoxypropyl-2″-cyanoacrylate, 2-(3'-methoxy)-butoxypropyl-2″-cyanoacrylate, 2-(2'-methoxy)-ethoxypropyl-2″-cyanoacrylate, 2-(2'-methoxy)-ethoxybutyl-2"-cyanoacrylate, and mixtures thereof.

[0235] 5. The two - part curable composition according to embodiment 4, characterized in that the cyanoacrylate monomer is selected from ethyl 2 - cyanoacrylate, 2 - methoxyethyl cyanoacrylate, and mixtures thereof.

[0236] 6. The two - part curable composition according to any one of embodiments 1 to 5, characterized in that based on the total weight of the first part of the composition, the total content of the cyanoacrylate monomer is in the range of 50 wt.% to 99 wt.%, preferably 70 wt.% to 97 wt.%, and more preferably 85 wt.% to 95 wt.%.

[0237] 7. The two - part curable composition according to any one of embodiments 1 to 6, characterized in that the (meth)acrylate monomer of part A of the two - part curable composition is selected from:

[0238] - a compound of general formula (III)

[0239] CH2=CR3(CO2R4) (III)

[0240] wherein R3 represents methyl or H (preferably H), and R4 is a hydrogen atom, a C1 - C8 straight - chain or branched - chain alkyl group, a C2 - C6 straight - chain or branched - chain alkoxyalkyl group, a furfuryl group or an isobornyl group;

[0241] - polyfunctional (meth)acrylates, and

[0242] - mixtures thereof.

[0243] 8. The two - part curable composition according to embodiment 7, characterized in that the (meth)acrylate monomer of formula (III) is selected from methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate.

[0244] 9. The two - part curable composition according to embodiment 7, characterized in that the (meth)acrylate monomer is selected from tricyclodecane dimethanol diacrylate, ethoxylated trimethylolpropane triacrylate, 1,4 - butanediol dimethacrylate, and tris(2 - hydroxyethyl)isocyanurate triacrylate.

[0245] 10. The two - part curable composition according to any one of embodiments 1 to 9, characterized in that based on the total weight of the first part of the composition, the total content of the (meth)acrylate monomer constitutes 1 wt.% to 10 wt.%.

[0246] 11. The two - part curable composition according to any one of embodiments 1 to 10, characterized in that the peroxide compound is selected from peresters, perborates, persulfates, peracetals or peroxides.

[0247] 12. The two - part curable composition according to embodiment 11, characterized in that the per - compound is tert - butyl perbenzoate (TBPB) or tert - butyl peroxide (TBP).

[0248] 13. The two - part curable composition according to any one of embodiments 1 to 12, characterized in that based on the total weight of the first part of the composition, the total content of the per - compound constitutes 1 wt.% to 10 wt.%, preferably 2 wt.% to 8 wt.%, and more preferably 3 wt.% to 7 wt.%.

[0249] 14. The two - part curable composition according to any one of embodiments 1 to 13, characterized in that the first part of the composition further contains one or more additives selected from stabilizers, tackifiers, accelerators, thixotropic agents, thickeners, toughening agents, plasticizers, antioxidants, pigments, colorants, and mixtures thereof.

[0250] 15. The two - part curable composition according to embodiment 14, characterized in that the first part of the composition further comprises a combination of a stabilizer, a thixotropic agent, and a thickener.

[0251] 16. The two - part curable composition according to embodiment 14 or 15, characterized in that the first part of the composition contains one or more stabilizers selected from free - radical stabilizers, acid stabilizers, and mixtures thereof.

[0252] 17. The two - part curable composition according to embodiment 16, characterized in that the first part of the composition contains a combination of a free - radical stabilizer and an acid stabilizer.

[0253] 18. The two - part curable composition according to embodiment 17, characterized in that as the stabilizer, the first part of the composition contains a combination of methanesulfonic acid, sulfur dioxide, boron trifluoride ethyl ether complex, hydroquinone, hydroquinone monomethyl ether, and 4,4′ - methylenebis(2,6 - di - tert - butylphenol).

[0254] 19. The two - part curable composition according to any one of embodiments 1 to 18, characterized in that the non - reactive diluent is a plasticizer.

[0255] 20. The two - part curable composition according to embodiment 19, characterized in that the plasticizer is selected from phthalates, citrates, azelates, adipates, sebacates, acetates, and non - reactive esters.

[0256] 21. The two - part curable composition according to embodiment 20, characterized in that the plasticizer is selected from triacetin, triethyl acetylcitrate, and tripropyl - 1,2,3 - triheptanoate.

[0257] 22. The two - part curable composition according to any one of embodiments 1 to 21, characterized in that, based on the total weight of the second part of the composition, the total content of the non - reactive diluent in the second part of the composition is in the range of 50 wt.% to 99.9 wt.%, preferably 60 wt.% to 90 wt.%, and more preferably 70 wt.% to 85 wt.%.

[0258] 23. The two - part curable composition according to any one of embodiments 1 to 22, characterized in that the transition metal catalyst is a transition metal salt.

[0259] 24. The two - part curable composition according to embodiment 23, characterized in that the transition metal salt is selected from Cu(ACN)4BF4, Cu(ACN)4PF6, Cu(BF4)2, copper(II) acetate, copper(II) octanoate, copper(II) benzoate, copper(II) chlorate, copper(II) carbonate, copper(II) acetylacetonate, copper(I) trifluoromethanesulfonate, copper(II) sulfate, iron(II) trifluoromethanesulfonate, ferrocene, iron(II) tetrafluoroborate, MnClO4, cobalt naphthenate, cobalt tetrafluoroborate.

[0260] 25. The two - part curable composition according to embodiment 24, characterized in that the transition metal salt is Cu(BF4)2 or its hydrate or solvate.

[0261] 26. The two - part curable composition according to any one of embodiments 1 to 25, characterized in that, based on the total weight of the second part of the composition, the content of the transition metal catalyst (expressed as the content of the transition metal) is in the range of 0.005 wt.% to 0.5 wt.%, and preferably 0.01 wt.% to 0.03 wt.%.

[0262] 27. The two - part curable composition according to any one of embodiments 1 to 26, characterized in that the second part of the composition contains electron - rich initiator classes for cyanoacrylate.

[0263] 28. The two - part curable composition according to embodiment 27, characterized in that the electron - rich initiator classes for cyanoacrylate are selected from organic bases, salts with hard anions, reactive inorganic fillers, calcium, zinc, and magnesium salts with organic counter - anions (provided that they do not contain ethylenic moieties), and mixtures thereof.

[0264] 29. The two - part curable composition according to embodiment 28, characterized in that the electron - rich initiator classes for cyanoacrylate are organic bases selected from caffeine, theobromine, 5 - chloro - 2 - methylbenzothiazole, and tetrahydroquinoline.

[0265] 30. The two - part curable composition according to embodiment 28, characterized in that the electron - rich initiator class for the cyanoacrylate is a salt with a hard anion selected from choline chloride and benzalkonium chloride.

[0266] 31. The two - part curable composition according to embodiment 28, characterized in that the electron - rich initiator class for the cyanoacrylate is hydrated calcium silicate with a tobermorite chemical structure as a reactive inorganic filler.

[0267] 32. The two - part curable composition according to embodiment 28, characterized in that the electron - rich initiator class for the cyanoacrylate is calcium, zinc, and magnesium salts with organic counter anions, provided that it does not contain an ethylenic moiety.

[0268] 33. The two - part curable composition according to any one of embodiments 1 to 32, characterized in that based on the total weight of the second part of the composition, the content of the electron - rich initiator constitutes 0.05 wt.% to 3 wt.%, preferably 0.1 wt.% to 2 wt.%, more preferably 0.5 wt.% to 1.2 wt.%.

[0269] 34. The two - part curable composition according to any one of embodiments 1 to 33, characterized in that the second part of the composition further contains one or more additives selected from thixotropic agents, thickeners, toughening agents, accelerators, tackifiers, pigments, colorants, and mixtures thereof.

[0270] 35. The two - part curable composition according to any one of embodiments 1 to 34, characterized in that the volume ratio between the first part and the second part is 10:1.

[0271] 36. The two - part curable composition according to embodiment 1, characterized in that it comprises:

[0272] a) A first part (Part A), which comprises:

[0273] i. 50 wt.% to 99 wt.%, preferably 70 wt.% to 97 wt.%, and more preferably 85 wt.% to 95 wt.% of one or more cyanoacrylate monomers,

[0274] ii. At least 1 wt.% of one or more (meth)acrylic monomers, and

[0275] iii. At least 1 wt.% of a per - compound,

[0276] wherein wt.% is based on the total weight of the first part of the composition,

[0277] b) A second part (Part B), which comprises:

[0278] i. 50 wt.% to 99.9 wt.%, preferably 60 wt.% to 90 wt.%, and more preferably 70 wt.% to 85 wt.% of a non-reactive diluent, and

[0279] ii. 0.001 wt.% to 2 wt.%, preferably 0.005 wt.% to 0.5 wt.%, and more preferably 0.01 wt.% to 0.03 wt.% of a transition metal catalyst, expressed as the content of the transition metal,

[0280] wherein wt.% is based on the total weight of the second part of the composition,

[0281] wherein the volume ratio between the first part and the second part is in the range of 4:1 to 10:1, preferably 10:1,

[0282] provided that the second part does not contain any ethylenically unsaturated monomers.

[0283] 37. The two-part curable composition according to embodiment 1, characterized in that it comprises:

[0284] a) A first part (Part A), which comprises:

[0285] i. At least 50 wt.%, preferably 50 wt.% to 99.9 wt.%, preferably 60 wt.% to 90 wt.%, and more preferably 70 wt.% to 85 wt.% of one or more cyanoacrylate monomers;

[0286] ii. 1 wt.% to 10 wt.% of one or more (meth)acrylate monomers;

[0287] iii. 1 wt.% to 10 wt.% of a peroxide compound;

[0288] iv. 0.001 wt.% to 0.2 wt.% of a stabilizer;

[0289] v. 2 wt.% to 10 wt.% by weight of a thixotropic agent;

[0290] vi. 2 wt.% to 10 wt.% by weight of a thickening agent;

[0291] wherein wt.% is based on the total weight of the first part of the composition,

[0292] b) A second part (Part B), which comprises:

[0293] i. At least 50 wt.%, preferably 50 wt.% to 99.9 wt.%, preferably 60 wt.% to 90 wt.%, and more preferably 70 wt.% to 85 wt.% of at least one non-reactive diluent;

[0294] ii. 0.001 wt.% to 2 wt.%, preferably 0.005 wt.% to 0.5 wt.%, and more preferably 0.01 wt.% to 0.03 wt.% of a transition metal catalyst, expressed as the content of the transition metal, and

[0295] iii. 0.1 wt.% to 2 wt.% of an electron-rich initiator compound;

[0296] iv. 2 wt.% to 15 wt.% of a thickening agent;

[0297] v. 2 wt.% to 8 wt.% of a thixotropic agent;

[0298] wherein wt.% is based on the total weight of the second part of the composition,

[0299] wherein the volume ratio between the first part and the second part is in the range of 4:1 to 10:1, preferably 10:1,

[0300] provided that the second part does not contain any ethylenic monomer.

[0301] 38. A syringe or cartridge containing a two-part curable cyanoacrylate composition according to any one of embodiments 1 to 37.

[0302] 39. Use of a two-part curable composition according to any one of embodiments 1 to 37 for bonding a substrate.

[0303] 40. Use of a two-part curable composition according to any one of embodiments 1 to 37 for filling depressions, cracks or holes in or between substrates.

[0304] 41. A method of bonding a substrate, characterized in that it comprises the following steps:

[0305] 1) Mixing together a two-part curable composition according to any one of embodiments 1 to 37,

[0306] 2) Applying the mixture of step 1) to at least one substrate, and

[0307] 3) Bringing the substrates together for a time sufficient to allow a bonding joint to form between the mated substrates.

[0308] 42. A method of repairing a depression, crack or hole in or between substrates, characterized in that it comprises the following steps:

[0309] 1) Mixing together a two-part curable composition according to any one of embodiments 1 to 37,

[0310] 2) Applying the mixture of step 1) to the depression, crack or hole in the substrate or to the upper part of the substrate, and optionally,

[0311] 3) Assemble the second substrate above the first substrate. Example

[0312] The following method is used to evaluate the performance of the claimed composition.

[0313] The Fixing Time (FT) is the time at which a bonded joint (250 mm 2 ) can support a 3 kg load for 10 s at 50% RH and at room temperature (23 ± 2 °C).

[0314] After immersing the sample in acetone (20 mL) for 24 h, a tolerance test is measured on the bulk cured polymer (0.3 g). The insoluble portion is filtered and dried to a constant mass at 60 °C and compared to the original mass or the cured material.

[0315] The tensile shear test data reflects the bond strength measured in MPa after assembling an overlap lap shear (standard specimen) component with a contact area of 25 mm 2 ; measured according to ASTM D1002, the bonded lap shear pieces are allowed to stand for 24 h after assembly before testing. A hot water resistance test is performed on the assembled samples immersed in hot water (at 60 °C) for 3 days.

[0316] The following components are used in the example:

[0317] ECA (ethyl cyanoacrylate) sold by Cartell Chemical Co., Ltd.

[0318] MECA (methyl methoxyethyl cyanoacrylate) sold by Cartell Chemical Co., Ltd.

[0319] SO2 sold by Carburos Metalicos, S.A.

[0320] Sold by Arkema CN1964CG (low molecular weight urethane dimethacrylate oligomer)

[0321] Sold by Arkema SR214 (1,4-butanediol dimethacrylate)

[0322] Sold by Arkema SR368 (tris-(2-hydroxyethyl) isocyanurate triacrylate)

[0323] Sold by Arkema SR454 (ethoxylated trimethylolpropane triacrylate)

[0324] Sold by Arkema SR833S (tricyclodecane dimethanol diacrylate)

[0325] PMMA (polymethyl methacrylate) 449, sold by Evonik

[0326] Poly(methyl methacrylate-co-butyl acrylate-co-methyl methacrylate) LA2140, sold by Kuraray Europe

[0327] D (hydrated calcium silicate inorganic filler with tobermorite structure), sold by Lapinus Fibers GTA (triacetin), sold by Oleon

[0328] GTH (propyl 1,2,3-triheptanoate), sold by Oleon

[0329] FS (hydrophobic fumed silica) R202, sold by Evonik

[0330] 1259 (acrylated aliphatic urethane oligomer), sold by Allnex.

[0331] The following products were obtained from Sigma Aldrich Merck:

[0332] Methanesulfonic acid, iron(II) trifluoromethanesulfonate, Cu(I)(ACN)4BF4, TBPB (tert-butyl peroxybenzoate), Cu(II)(BF4)2.

[0333] Examples 1.1 to 1.6 : Two-part curable composition

[0334] The composition of part A is outlined in Table 1, and the composition of part B is outlined in Table 2. The contents are expressed as wt.% based on the total weight of the corresponding part A and part B compositions.

[0335] The adhesive is manufactured by mixing part A with part B at a 10:1 (A:B) mixing ratio using a Sulzer Mixpac syringe and an appropriate static mixer. In all these examples, the Cu(I) salt is the transition metal catalyst and is called The calcium silicate of D is an electron-rich initiator for cyanoacrylate.

[0336] Table 1

[0337]

[0338] Table 2

[0339]

[0340] Examples 2.1 to 2.3 : Two-part curable composition

[0341] The additional Component A and Component B compositions are summarized in Tables 3 and 4 respectively. The contents are expressed as wt.% based on the total weight of the corresponding Component A and Component B compositions.

[0342] The adhesives were made in the same manner as described in Example 1. In these examples, different transition metal salt catalysts were selected and used with or without the exemplified calcium silicate initiator for cyanoacrylate ( D). The adhesives were made by mixing Component A and Component B in a 10:1 (A:B) mixing ratio using a Sulzer Mixpac syringe and an appropriate static mixer.

[0343] Table 3

[0344] Example 2.1.A 2.2.A 2.3.A MECA 83.99815 83.99815 83.99815 MSA 0.00085 0.00085 0.00085 <![CDATA[SO2]]> 0.001 0.001 0.001 PMMA 4 4 4 FS 5 5 5 TBPB 5 5 5 SR454 2 2 2

[0345] Table 4

[0346]

[0347] Comparative Example 3 : Two-part cyanoacrylate composition

[0348] Two-part cyanoacrylate comparison compositions are summarized as Component A and Component B in Tables 5 and 6 respectively. The contents are expressed as wt.% based on the total weight of the corresponding Component A and Component B compositions.

[0349] Compositions 3.3.A and 3.3.B correspond to products from the series, and information on the composition is available through MSDS data.

[0350] Compositions 3.4.A and 3.4.B correspond to the examples of WO-A-2013 / 111036 disclosed in Tables 1 and 2.

[0351] The adhesives were made in the same manner as described in Example 1. In these examples, the peroxide compound was missing from Component A.

[0352] Table 5

[0353] Example 3.1.A 3.2.A. 3.3.A 3.4.A MECA 80.99815 85.99815 - - ECA - - 60-80 94.995 Ethylene-vinyl acetate copolymer - - 10-30 - MSA 0.00085 0.00085 Not specified - <![CDATA[SO2]]> 0.001 0.001 Not specified - <![CDATA[BF3]]> - - Not specified 0.005 PMMA 6 6 Not specified - FS 6 6 Not specified - TBPB 5 - 5-10 5 SR454 2 2 - - Others - - ＜25

[0354] Table 6

[0355]

[0356] *TRIEGMA: Triethylene glycol dimethacrylate

[0357] The 2K adhesive containing Part A of Comparative Example 3.1 and Part B of Comparative Example 3.1 packed in a 10:1 syringe could not be used after being stored at room temperature for 4 months because Part B was unstable due to the combination of a transition metal catalyst and an ethylenic component.

[0358] The 2K adhesive obtained from Part A:Part B = 10:1 of Comparative Example 3.2 was tested as shown in Example 4.

[0359] The 2K adhesives obtained from Part A:Part B = 1:1 of Comparative Examples 3.3 and 3.4 were tested as shown in Example 4.

[0360] Example 4 : Testing two-part cyanoacrylate adhesive

[0361] Table 7 illustrates that the adhesives obtained from the compositions described in Examples 1.1, 1.2, 1.3, 1.4, 1.5 and 1.6 showed a high degree of insolubility in acetone after being soaked for 24 h, indicating crosslinking due to the reaction of a percompound with a copper-based transition metal salt to generate free radicals and the copolymerization of the bulk cyanoacrylate with a small concentration of polyfunctional (meth)acrylate present. The free radical reaction that produces the desirable solvent resistance and durability due to crosslinking does not prevent the adhesive from having the ability to rapidly fix and cure like a traditional super strong glue.

[0362] On the contrary, when there is no percompound as in Comparative Example 3.2, such insolubility does not occur, and the adhesive does not crosslink and is easily soluble.

[0363] Rapid fixation (<1 min) of the composition was observed even in the presence of several different (meth)acrylic crosslinkers. As commercial products, Comparative Example 3.3 and the 2K adhesive from WO-A-2013 / 111036 (Comparative Example 3.4) did perform well in terms of durability (high insolubility due to crosslinking), but could not show rapid fixation (≥10 min).

[0364] Table 8 shows the results obtained with Comparative Examples 3.2 - 3.4.

[0365] Table 7

[0366]

[0367] Table 8

[0368] Example 3.2 3.3 3.4 FT (mild steel) 30s 12 min >15 min FT (ABS) 60s >20 min 10 min Insoluble in 24 h (acetone) 0％ 100％ 95％

[0369] Example 5 : Testing two-part cyanoacrylate adhesive

[0370] Table 10 illustrates that the adhesives obtained by mixing Part A and Part B of the compositions described in Examples 2.1 - 2.3 showed a high degree of insolubility (from 76% to 89%) in acetone after 24 h of immersion, supporting cross - linking occurring due to the reaction of the per - compound with the transition metal catalyst leading to free - radical generation and copolymerization of the bulk cyanoacrylate with the small concentration of polyfunctional (meth)acrylate present.

[0371] Table 10 also illustrates the effect of combining an electron - rich initiator for cyanoacrylate (e.g., D, which is present in Part B for Adhesive 2.2 but not in Part B for Adhesive 2.3) with the transition - metal catalyst in Part B. When both are included in the composition (i.e., used together), the adhesive shows rapid fixation (30 s on mild steel), bulk curing within a relatively short period (1 h), and durability demonstrated by solvent resistance, which results in a high degree of insolubility in acetone, stemming from the cross - linking and copolymerization of the cyanoacrylate with a certain concentration of polyfunctional acrylate - ethoxylated trimethylolpropane triacrylate (sR454), which alone in cross - linking cannot result in the illustrated insolubility.

[0372] Table 10

[0373]

Claims

1. A two - part curable composition, characterized in that It comprises: a) A first part (Part A), which comprises: i. At least 50 wt.% of one or more cyanoacrylate monomers, ii. At least 1 wt.% of one or more (meth)acrylic monomers selected from: - Compounds of general formula (III) CH2=CR3(CO2R4) (III) wherein R3 represents methyl or H, and R4 is a hydrogen atom, a C1-C8 straight or branched alkyl group, a C2-C6 straight or branched alkoxyalkyl group, a furfuryl group or an isobornyl group; - Polyfunctional (meth)acrylates selected from butanediol di(meth)acrylate, hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, triethylenedimethacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane tri(meth)acrylate (TMPTA), ethoxylated trimethylolpropane tri(meth)acrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate (PETA), pentaerythritol tetramethacrylate (PETMA), dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, bisphenol A diacrylate, bisphenol A dimethacrylate, ethoxylated bisphenol A diacrylate, propoxylated bisphenol A diacrylate, and mixtures thereof; (meth)acrylate-functionalized oligomers and (meth)acrylate-functionalized resins; and - Mixtures thereof, and iii. At least 1 wt.% of a peroxide compound, wherein wt.% is based on the total weight of the first part of the composition, b) A second part (Part B), which comprises: i. At least 50 wt.% of a non-reactive diluent, and ii. 0.001 wt.% to 2 wt.% of a transition metal catalyst, expressed as the content of the transition metal, wherein wt.% is based on the total weight of the second part of the composition, wherein the volume ratio between the first part and the second part is in the range of 4:1 to 10:1, provided that the second part does not contain any ethylenic monomers.

2. The two-part curable composition according to claim 1, wherein The first part of the composition further contains one or more additives selected from stabilizers, tackifiers, accelerators, thixotropic agents, thickeners, toughening agents, plasticizers, antioxidants, pigments, colorants, and mixtures thereof.

3. The two-part curable composition according to claim 2, characterized in that The first part of the composition contains one or more stabilizers selected from free radical stabilizers, acid stabilizers, and mixtures thereof.

4. The two-part curable composition according to claim 1 or 2, characterized in that The non-reactive diluent is a plasticizer.

5. The two-part curable composition according to claim 1 or 2, characterized in that The transition metal catalyst is a transition metal salt.

6. The two-part curable composition according to claim 5, wherein The transition metal salts are selected from Cu(ACN)4BF4, Cu(ACN)4PF6, Cu(BF4)2, copper(II) acetate, copper(II) octoate, copper(II) benzoate, copper(II) chlorate, copper(II) carbonate, copper(II) acetylacetonate, copper(I) trifluoromethanesulfonate, copper(II) sulfate, iron(II) trifluoromethanesulfonate, ferrocene, iron(II) tetrafluoroborate, MnClO4, cobalt naphthenate, cobalt tetrafluoroborate.

7. The two-part curable composition according to claim 1 or 2, characterized in that The second part of the composition contains electron-rich initiator classes for cyanoacrylates.

8. The two-part curable composition according to claim 1 or 2, characterized in that The (meth)acrylic monomers of part A of the two-part curable composition are selected from: - Compounds of general formula (III) CH2=CR3(CO2R4) (III) wherein R3 represents methyl or H, and R4 is a hydrogen atom, a C1-C8 straight or branched alkyl group, a C2-C6 straight or branched alkoxyalkyl group, a furfuryl group or an isobornyl group; - Polyfunctional (meth)acrylates selected from butanediol di(meth)acrylate, hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, triethylenedimethacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane tri(meth)acrylate (TMPTA), ethoxylated trimethylolpropane tri(meth)acrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate (PETA), pentaerythritol tetramethacrylate (PETMA), dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, bisphenol A diacrylate, bisphenol A dimethacrylate, ethoxylated bisphenol A diacrylate, propoxylated bisphenol A diacrylate, and mixtures thereof; and - Mixtures thereof.

9. The two-part curable composition according to claim 1, characterized in that It comprises: a) A first part (part A) which comprises: i. 50 wt.% to 97 wt.% of one or more cyanoacrylate monomers, ii. at least 1 wt.% of one or more (meth)acrylic monomers, and iii. at least 1 wt.% of a peroxide compound, wherein wt.% is based on the total weight of the first part of the composition, b) A second part (part B) which comprises: i. 50 wt.% to 99.9 wt.% of a non-reactive diluent, and ii. 0.001 wt.% to 2 wt.% of a transition metal catalyst, expressed as the content of the transition metal, wherein wt.% is based on the total weight of the second part of the composition, wherein the volume ratio between the first part and the second part is in the range of 4:1 to 10:1, provided that the second part does not contain any ethylenic monomers.

10. The two-part curable composition according to claim 1, wherein It comprises: a) A first part (part A) which comprises: i. 50 wt.% to 90 wt.% of one or more cyanoacrylate monomers; ii. 1 wt.% to 10 wt.% of one or more (meth)acrylate monomers; iii. 1 wt.% to 10 wt.% of a percompound; iv. 0.001 wt.% to 0.2 wt.% of a stabilizer; v. 2 wt.% to 10 wt.% of a thixotropic agent by weight; vi. 2 wt.% to 10 wt.% of a thickening agent by weight; wherein wt.% is based on the total weight of the first part of the composition, b) A second part (Part B), which comprises: i. 50 wt.% to 90 wt.% of at least one non-reactive diluent; ii. 0.001 wt.% to 2 wt.% of a transition metal catalyst, expressed as the content of the transition metal, and iii. 0.1 wt.% to 2 wt.% of an electron-rich initiator compound; iv. 2 wt.% to 15 wt.% of a thickening agent; v. 2 wt.% to 8 wt.% of a thixotropic agent; wherein wt.% is based on the total weight of the second part of the composition, wherein the volume ratio between the first part and the second part is in the range of 4:1 to 10:1, provided that the second part does not contain any ethylenically unsaturated monomers.

11. A syringe or cartridge containing a two-part curable composition according to any one of claims 1 to 10.

12. Use of the two-part curable composition according to any one of claims 1 to 10 for bonding substrates.

13. Use of the two-part curable composition according to any one of claims 1 to 10 for filling depressions, cracks or holes in or between substrates.

14. A method for bonding a substrate, characterized in that It comprises the following steps: 1) Mixing together the two-part curable composition according to any one of claims 1 to 10, 2) Applying the mixture of step 1) to at least one of the substrates, and 3) Bringing the substrates together for a time sufficient to allow a bonding joint to form between the brought-together substrates.

15. A method for repairing depressions, cracks or holes in or between substrates, characterized in that It comprises the following steps: 1) Mixing together the two-part curable composition according to any one of claims 1 to 10, 2) Applying the mixture of step 1) into a depression, crack or hole in a substrate or onto the upper part of a substrate, and optionally, 3) Assembling a second substrate above the first substrate.

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