Dual curing compositions based on methacrylate functional compounds

Abstract

The present application relates to a dual curing composition that is both heat-curable and light-curable, comprising, based on the weight of the composition: 20 to 90 wt.% of a) at least one epoxy methacrylate compound having at least two methacrylate groups; and 10 to 80 wt.% of b) at least one polythiol compound, wherein the composition is characterized in that the molar ratio of thiol (-SH) groups to (meth) acrylate groups is in the range of 0.5: 1 to 1: 1.

Description

Technical Field

[0001] The present disclosure relates to a dual-cure composition. More specifically, the present disclosure relates to a composition that can be cured using actinic radiation and / or heat, the composition comprising an epoxy methacrylate monomer and a thiol-functional compound. Background Art

[0002] Compositions curable by actinic radiation (e.g., coating compositions) can generally be cured relatively quickly by exposure to a radiation source. Rapid curing of the composition allows manufacturers to increase throughput, for example, in industrial coating processes. However, many coated substrates will have areas that are not easily exposed to actinic radiation: for example, it may be difficult to fully expose conformal coatings applied to the surfaces of circuit boards and electronic components because these surfaces are often highly contoured. This difficulty in exposing the applied composition to actinic radiation leads to the problem that a portion of the applied composition in the "shadow" area will remain uncured.

[0003] The present disclosure seeks to solve the problem of obtaining complete cure of photocurable compositions based on (meth)acrylate functional compounds throughout areas that are not illuminated by the incident initiating light source. This problem has previously been solved in the art by providing compositions that can be cured upon exposure to heat in addition to being curable upon exposure to actinic radiation. Such compositions are referred to as dual-cured.

[0004] US2007029034A1 (Mgaya et al.) discloses a dual-cure adhesive composition comprising: a) a water-based emulsion of at least one vinyl ester homopolymer or copolymer; b) at least one (meth)acrylate-functional monomer and / or oligomer capable of being polymerized and / or crosslinked by exposure to ultraviolet or visible light; and c) at least one photoinitiator.

[0005] U.S. Pat. No. 10,174,146 B2 (Morin et al.) discloses a dual-cure composition applied using the following method steps: a) mixing at least one polymerizable acrylic compound, a thermal initiator, a photoinitiator, and a peroxide to form a mixture, wherein the peroxide has a decomposition temperature; b) exposing the mixture to light for a first time sufficient to produce a first curing agent; and c) after the mixture is exposed to light, exposing the mixture to a temperature below the decomposition temperature of the peroxide for a second time sufficient to produce a second curing agent.

[0006] WO / 2013 / 023545 (Henkel China Company Ltd.) discloses a dual-cure adhesive composition comprising, based on the total weight of the adhesive composition: 10 to 90 wt.% of a photocurable oligomer or polymer having a (meth)acryloyloxy or vinyl side group; 5 to 55 wt.% of a (meth)acrylate; 0 to 50 wt.% of a liquid polybutadiene; 0.5 to 5 wt.% of a UV photoinitiator; and 0.5 to 5 wt.% of a thermal initiator.

[0007] KR102155180 B1 (KCC Corporation) describes a dual-cure adhesive composition capable of photocuring and thermal curing, the adhesive composition comprising: an epoxy (meth)acrylate oligomer, a polyol (meth)acrylate oligomer, a (meth)acrylate monomer, a photoinitiator, and a thermal initiator.

[0008] It should be noted that photoinitiators are present in these prior art compositions. In addition, those skilled in the art will appreciate that working examples of such prior art compositions typically include photosensitizers to increase the efficiency of the photoinitiator in utilizing the energy delivered by increasing the rate of photoinitiated polymerization or by changing the wavelength at which polymerization occurs. Photoinitiators and, where applicable, photosensitizers may produce residual compounds in the final cured product from photochemical reactions. These residues can be detected by conventional analytical techniques, such as: infrared, ultraviolet and NMR spectroscopy; gas or liquid chromatography; and mass spectrometry. Therefore, the prior art composition may contain a cured matrix (co)polymer and a detectable amount of at least residues from the photoinitiator. Summary of the invention

[0009] According to a first aspect of the present invention, there is provided a dual-curing composition that is both heat-curable and photo-curable, the composition comprising the following components based on the weight of the composition:

[0010] 20 to 90 wt. % of a) at least one epoxy methacrylate compound having at least two methacrylate groups; and

[0011] 10 to 80 wt.% of b) at least one polythiol compound,

[0012] The composition is characterized in that the molar ratio of thiol (—SH) groups to (meth)acrylate groups is in the range of 0.5:1 to 1:1.

[0013] In one embodiment, the dual cure composition comprises, based on the weight of the composition:

[0014] 40 to 80 wt.%, preferably 50 to 80 wt.% of a) at least one epoxy methacrylate compound having at least two methacrylate groups;

[0015] 20 to 60 wt.%, preferably 20 to 50 wt.% of b) at least one polythiol compound; and,

[0016] 0 to 50 wt.%, preferably 0 to 30 wt.%, of c) at least one ethylenically unsaturated monomer,

[0017] The composition described therein is characterized in that the molar ratio of thiol (—SH) groups to (meth)acrylate groups is in the range of 0.6:1 to 1:1, preferably 0.8:1 to 1:1.

[0018] The dual-cure composition should be substantially free of free radical photoinitiators and / or thermal free radical initiators. In fact, effective compositions according to the present disclosure that are free of both thermal free radical initiators and free radical photoinitiators have been shown to be effectively cured independently under heat and light irradiation. For the sake of completeness, in important embodiments, the compositions of the present invention may be substantially free of free radical initiators.

[0019] The or each epoxy methacrylate compound present in the composition is preferably an adduct of methacrylic acid and a polyepoxide. In an exemplary embodiment, the polyepoxide is selected from: polyglycidyl ethers of polyhydric alcohols; polyglycidyl ethers of polyhydric phenols; polyglycidyl esters of polycarboxylic acids; and epoxidized polyethylenically unsaturated hydrocarbons. More specifically, the polyepoxide is a diglycidyl ether selected from: diglycidyl ethers of aliphatic and alicyclic diols; diglycidyl ethers based on bisphenol A; diglycidyl ethers of bisphenol F; diglycidyl ethers based on polyalkylene glycols; and glycidyl ethers based on polycarbonate diols.

[0020] The or each polythiol compound contained in the composition should preferably have 2 to 5 thiol groups. Independently of or in addition to this functionality, the or each polythiol compound contained in the composition should have a weight average molecular weight (Mw) of less than 20,000 Daltons, preferably 200 to 800 Daltons.

[0021] Exemplary polythiol compounds are polyesters of thiocarboxylic acids, and particular mention may be made, alone or in combination, of the following: pentaerythritol tetrakis(3-mercaptopropionate); pentaerythritol tetrakis(3-mercaptobutylate); trimethylolpropane trimercaptoacetate (TMPMP); tris(2-(mercaptopropionyloxy)ethyl)isocyanate; and ethylene glycol dimercaptoacetate.

[0022] Good results have been obtained where the dual cure composition comprises, based on the weight of the composition:

[0023] 40 to 80 wt %, preferably 50 to 80 wt % of a) an epoxy methacrylate compound having at least two methacrylate groups, wherein the epoxy methacrylate compound is an adduct of methacrylic acid and a polyglycidyl ether of a polyhydric phenol;

[0024] 20 to 60 wt%, preferably 20 to 50 wt% of b) a polythiol compound selected from the group consisting of pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), trimethylolpropane trimercaptoacetate (TMPMP), tris(2-(mercaptopropionyloxy)ethyl)isocyanate, ethylene glycol dimercaptoacetate, and combinations thereof; and

[0025] 0 to 50 wt.%, preferably 0 to 30 wt.%, of c) at least one ethylenically unsaturated monomer,

[0026] The composition described therein is characterized in that the molar ratio of thiol (—SH) groups to (meth)acrylate groups is in the range of 0.6:1 to 1:1, preferably 0.8:1 to 1:1.

[0027] In an important embodiment of the present disclosure, there is provided a dual-cure composition comprising, based on the weight of the composition:

[0028] 40 to 80 wt %, preferably 50 to 80 wt % of a) an epoxy methacrylate compound having at least two methacrylate groups, wherein the epoxy methacrylate compound is an adduct of methacrylic acid and a diglycidyl ether based on bisphenol A;

[0029] 20 to 60 wt.%, preferably 20 to 50 wt.% of b) a polythiol compound selected from the group consisting of pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and combinations thereof; and

[0030] 0 to 50 wt.%, preferably 0 to 30 wt.%, of c) at least one ethylenically unsaturated monomer,

[0031] The composition described therein is characterized in that the molar ratio of thiol (—SH) groups to (meth)acrylate groups is in the range of 0.6:1 to 1:1, preferably 0.8:1 to 1:1.

[0032] According to a second aspect of the present invention there is provided the use of a dual cure composition as defined above and in the appended claims as a coating, adhesive or sealant. Also envisaged is the use of the dual cure composition in a composite material.

[0033] definition

[0034] As used herein, the singular forms "a," "an," "an," "said," and "the" include plural referents unless the context clearly dictates otherwise.

[0035] As used herein, the terms "comprising" and "including" are synonymous with "containing" or "including" and are inclusive or open-ended and do not exclude additional, unrecited members, elements, or method steps.

[0036] As used herein, the term "consisting of" excludes any elements, ingredients, members, or method steps not specified.

[0037] When quantities, concentrations, sizes and other parameters are expressed in the form of ranges, preferred ranges, upper values, lower values, or preferred upper and lower values, it should be understood that any range obtainable by combining any upper value or preferred upper value with any lower value or preferred lower value is also specifically disclosed, regardless of whether the obtained range is explicitly mentioned in the context.

[0038] Furthermore, according to standard understandings, weight ranges expressed as "0 to x" specifically include 0 wt. %: the ingredient defined by the range may not be present in the composition, or may be present in the composition in an amount not higher than x wt. %.

[0039] The words "preferred", "preferably", "desirably", and "especially" are frequently used herein to refer to embodiments of the present disclosure that may provide particular benefits under certain circumstances. However, the recitation of one or more preferred, desired, or particular embodiments does not mean that other embodiments are not useful, and is not intended to exclude those other embodiments from the scope of the present disclosure.

[0040] The word "exemplary" is used herein to mean used as an example, instance or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as being preferred or advantageous over other aspects or designs. On the contrary, the use of the word exemplary is intended to present concepts in a concrete manner.

[0041] As used throughout this application, the word "may" is used in a permissive sense, i.e., having the potential to be used, rather than in a mandatory sense.

[0042] As used herein, room temperature is 23°C ± 2°C.

[0043] Molecular weights referred to in this specification to describe the macromolecular, oligomeric and polymeric components of the curable composition may be measured by gel permeation chromatography (GPC), for example according to ASTM 3536, using polystyrene calibration standards.

[0044] Unless otherwise specified, the viscosity of the compositions described herein is measured using a Brookfield viscometer under standard conditions of 20° C. and 50% relative humidity (RH). The calibration method, spindle type and rotation speed of the Brookfield viscometer are selected according to the manufacturer's instructions appropriate for the composition to be measured.

[0045] As used herein, the term "monomer" refers to a substance that can undergo polymerization to provide a building block to the chemical structure of a polymer. The term "monofunctional" as used herein refers to having one polymerizable moiety. The term "multifunctional" as used herein refers to having more than one polymerizable moiety.

[0046] As used herein, the term "equivalent (eq.)" relates to the relative number of reactive groups present in a reaction, as is conventional in chemical notation.

[0047] As used herein, the term "equivalent weight" refers to the molecular weight divided by the number of functional groups involved. Thus, "epoxy equivalent weight" (EEW) refers to the weight of a resin containing 1 equivalent of epoxy, in grams.

[0048] As used herein, the term "epoxide" refers to a compound characterized by the presence of at least one cyclic ether group, i.e., a compound in which an ether oxygen atom is attached to two adjacent carbon atoms to form a cyclic structure. The term is intended to include monoepoxides, polyepoxides (having two or more epoxy groups), and epoxy-terminated prepolymers. The term "monoepoxide" refers to an epoxy compound having one epoxy group. The term "polyepoxide" refers to an epoxy compound having at least two epoxy groups. The term "diepoxide" refers to an epoxy compound having two epoxy groups.

[0049] The epoxy compound may be unsubstituted, but may also be inertly substituted. Exemplary inert substituents include chlorine, bromine, fluorine and phenyl.

[0050] The term "polythiol" as used herein refers to a simple or complex organic compound having at least two pendant or terminal thiol groups (-SH) per molecule. Such polythiol can generally be represented by the formula R t –(SH) c represents, where c is an integer with a value of at least 2, and R t It is a polyvalent organic part with a valence of c.

[0051] As used herein, the term "free radical initiator" refers to any chemical species that, when exposed to sufficient energy, such as energy in the form of light or heat, decomposes into two components that are uncharged but each have at least one unpaired electron. Thus, thermal free radical initiators generate free radicals when exposed to heat. Known thermal free radical initiators include, but are not limited to, peroxide compounds, azo compounds, and persulfate compounds.

[0052] As used herein, the term "photoinitiator" refers to a compound that can be activated by an energetically active beam (e.g., electromagnetic radiation) when irradiated therewith. Specifically, a "free radical photoinitiator" refers herein to a photoactive compound that generates free radicals that can initiate polymerization or reaction herein by addition to C=C double bonds present in the composition. Such free radical photoinitiators are generally classified as Norrish Type I and Norrish Type II photoinitiators. Norrish Type I free radical photoinitiators undergo a Norrish Type I reaction when exposed to actinic radiation: the reaction is defined by IUPAC as the α-cleavage of an excited carbonyl compound, resulting in an acyl-alkyl radical pair (from an acyclic carbonyl compound) or an acyl-alkyl diradical (from a cyclic carbonyl compound) as the primary photoproduct. When exposed to actinic radiation, Norrish Type II free radical photoinitiators undergo a Norrish Type II reaction: the reaction is defined by IUPAC as the photochemical abstraction of a γ-hydrogen by an excited carbonyl compound to produce a 1,4-diradical as the primary photoproduct.

[0053] As used herein, "(meth)acryl" refers to the shorthand term for "acryl" and / or "methacryl." Therefore, the term "(meth)acrylate" refers to the general term for acrylate and methacrylate.

[0054] As used herein, “C1-C n "Alkyl" refers to a monovalent group containing 1 to n carbon atoms, which is a radical of an alkane, and includes straight-chain and branched organic groups. Therefore, "C1-C 18 "Alkyl" refers to a monovalent group containing 1 to 18 carbon atoms, which is a radical of an alkane, and includes straight-chain and branched organic groups. Generally, it should be noted that alkyl groups (C1-C 12 The term "alkyl" refers to an alkyl group (i.e., an alkyl group having 1 to 8 carbon atoms (C1-C8 alkyl group). Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, and 2-ethylhexyl. In the present invention, such alkyl groups may be unsubstituted or substituted with one or more halogens. Where applicable to a given moiety (R), it will be noted in the specification that one or more non-halogen substituents are permitted in the alkyl group.

[0055] The term "C1-C 18 "Hydroxyalkyl" refers to a HO-(alkyl) group having from 1 to 18 carbon atoms, wherein the point of attachment of the substituent is through the oxygen atom and alkyl is as defined above.

[0056] "Alkoxy" refers to a monovalent group represented by -OA, where A is an alkyl group: non-limiting examples of which are methoxy, ethoxy and isopropoxy. The term "C1-C 18 "Alkoxyalkyl" refers to an alkyl group having an alkoxy substituent as defined above, wherein the moiety (alkyl-O-alkyl) contains a total of 1 to 18 carbon atoms: such groups include methoxymethyl (-CH2OCH3), 2-methoxyethyl (-CH2CH2OCH3) and 2-ethoxyethyl. Similarly, the term "C7-C 18 "Alkoxyaryl" refers to an aryl group having an alkoxy substituent as defined above and wherein the moiety (aryl-O-alkyl) has a total of 7 to 18 carbon atoms.

[0057] The term "C2-C4 alkylene" as used herein is defined as a saturated divalent hydrocarbon group having 2 to 4 carbon atoms.

[0058] The term “C3–C 18 "Cycloalkyl" is understood to mean a saturated monocyclic or polycyclic hydrocarbon radical having from 3 to 18 carbon atoms. In the present invention, such cycloalkyl groups may be unsubstituted or substituted by one or more halogens. Where applicable to a given moiety (R), it will be noted in the specification that one or more non-halogen substituents are permitted in the cycloalkyl group. Examples of cycloalkyl groups include: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantane, and norbornane.

[0059] As used herein, "C6-C 18 "Aryl" refers to monocyclic, bicyclic and tricyclic ring systems, wherein the monocyclic ring system is aromatic or at least one ring of the bicyclic or tricyclic ring system is aromatic. Bicyclic and tricyclic ring systems include benzo-fused 2-3 membered carbon rings. In the present invention, such aryl groups may be unsubstituted or substituted with one or more halogens. Where applicable to a given moiety (R), it will be noted in the specification that one or more non-halogen substituents are permitted in the aryl group. Exemplary aryl groups include: phenyl; (C1-C4) alkylphenyls, such as tolyl and ethylphenyl; indenyl; naphthyl; tetrahydronaphthyl; tetrahydroindenyl; tetrahydroanthracenyl; and anthracenyl. And it may be noted that phenyl is preferred.

[0060] As used herein, “C2-C 20"Alkenyl" refers to a hydrocarbon group having 2 to 20 carbon atoms and at least one ethylenically unsaturated unit. The alkenyl group may be straight chain, branched or cyclic, and may be optionally substituted with one or more halogens. Where applicable to a given moiety (R), it will be noted in the specification that one or more non-halogen substituents are permitted in the alkenyl group. The term "alkenyl" also includes groups having "cis" and "trans" configurations, or "E" and "Z" configurations, as understood by those of ordinary skill in the art. However, in general, it should be noted that alkenyl groups containing 2-10 (C 2-10 ) or 2-8 (C 2-8 ) carbon atom. 12 Examples of alkenyl groups include, but are not limited to: -CH=CH2; -CH=CHCH3; -CH2CH═CH2; -C(═CH2)(CH3); -CH=CHCH2CH3; -CH2CH=CHCH3; -CH2CH2CH=CH2; -CH=C(CH3)2; -CH2C(═CH2)(CH3); -C(═CH2)CH2CH3; -C(CH3)═CHCH3; -C(CH3)CH═CH2; -CH=CHCH2CH2CH3; -CH2CH =CHCH2CH3; -CH2CH2CH=CHCH3; -CH2CH2CH2CH=CH2; -C(=CH2)CH2CH2CH3; -C(CH3)=CHCH2CH3; -CH(CH3)CH=CHCH; -CH(CH3)CH2CH=CH2; -CH2CH=C(CH3)2; 1-cyclopent-1-enyl; 1-cyclopent-2-enyl; 1-cyclopent-3-enyl; 1-cyclohex-1-enyl; 1-cyclohex-2-enyl; and, 1-cyclohexyl-3-enyl.

[0061] As used herein, "alkaryl" refers to an aryl group substituted with an alkyl group, wherein both groups are as defined above. Additionally, as used herein, "aralkyl" means an alkyl group substituted with an aryl group as defined above.

[0062] As used herein, the term "hetero" refers to a group or moiety that contains one or more heteroatoms, such as N, O, Si, and S. Thus, for example, "heterocyclic" refers to a cyclic group having, for example, N, O, Si, or S as part of the ring structure. "Heteroalkyl," "heterocycloalkyl," and "heteroaryl" moieties are alkyl, cycloalkyl, and aryl groups, respectively, as defined above, containing N, O, Si, or S as part of their structure. DETAILED DESCRIPTION

[0063] a) Epoxy methacrylate compounds

[0064] The composition comprises at least one epoxy methacrylate compound having at least two methacrylate groups in an amount of 20 to 90 wt.% based on the weight of the composition: preferably the epoxy methacrylate compound comprises 40 to 80 wt.%, such as 50 to 80 wt.% of the composition.

[0065] Epoxy methacrylate compounds can be obtained as reaction products of methacrylic acid and polyepoxides. Without intending to limit the invention, suitable reactant polyepoxides can be liquids, solids or solutions in solvents. In addition, such polyepoxides should have an epoxy equivalent weight of 100 to 700 g / eq, for example 120 to 320 g / eq. And usually, diepoxides with an epoxy equivalent weight of less than 500 g / eq. or even less than 400 g / eq. are preferred: this is mainly from a cost point of view, because in their production, lower molecular weight epoxy resins require more limited treatment in purification.

[0066] As examples of types or groups of polyepoxides that can react with methacrylic acid, mention may be made of: polyglycidyl ethers of polyols and polyphenols; polyglycidyl esters of polycarboxylic acids; and epoxidized polyethylenically unsaturated hydrocarbons.

[0067] The use of diepoxides is preferred. For example, suitable diglycidyl ether compounds may be aromatic, aliphatic or alicyclic in nature and may therefore be derived from dihydric phenols and diols. Useful classes of such diglycidyl ethers are: diglycidyl ethers of aliphatic and alicyclic diols (e.g. 1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,12-dodecanediol, cyclopentanediol and cyclohexanediol); diglycidyl ethers based on bisphenol A; diglycidyl ethers of bisphenol F; diglycidyl phthalate, diglycidyl isophthalate and diglycidyl terephthalate; diglycidyl ethers based on polyalkylene glycols, in particular polypropylene glycol diglycidyl ether; and glycidyl ethers based on polycarbonate diols. Other suitable diepoxides that may also be mentioned include: diunsaturated fatty acids C1-C 18 Alkyl ester diepoxides; butadiene diepoxide; polybutadiene diglycidyl ether; vinyl cyclohexene diepoxide; and limonene diepoxide.

[0068] Other exemplary polyepoxides include, but are not limited to: glycerol polyglycidyl ether; trimethylolpropane polyglycidyl ether; pentaerythritol polyglycidyl ether; diglycerol polyglycidyl ether; polyglycerol polyglycidyl ether; and sorbitol polyglycidyl ether.

[0069] Examples of highly preferred reactant polyepoxides include: bisphenol-A epoxy resin; bisphenol-F epoxy resin; bisphenol A / F epoxy resin blends; polypropylene glycol diglycidyl ether, such as DER TM 732; Linear epoxy phenolic resins, such as DEN TM 438; Brominated epoxy resins, such as DER TM 542; Castor oil triglycidyl ether, such as ERISYS TM GE-35H; Polyglycerol-3-polyglycidyl ether, such as ERISYS TM GE-38; and sorbitan glycidyl ether, such as ERISYS TM GE-60.

[0070] Epoxy methacrylate compounds having at least two methacrylate groups can of course be obtained from commercial sources. Representative commercially available epoxy diacrylates include, but are not limited to, epoxy dimethacrylate oligomer Ebecryl 611, available from Daicel-Cytec Company Ltd; and bisphenol A epoxy dimethacrylate compound Epoxyester 3000MK, available from Kyoeisha Chemical Co. Ltd.

[0071] It should be noted that the polyepoxide compound that can be used to form the epoxy methacrylate adduct can be either a monomer or an oligomer. It is believed that the inclusion of a monomeric epoxy methacrylate in the composition of the present invention will generally produce a cured product having hard, wear-resistant properties. Conversely, the inclusion of an oligomeric multifunctional acrylate will generally produce a slightly softer but more flexible cured product. Of course, the use of both monomeric and oligomeric epoxy methacrylate compounds can balance the desired properties of the cured product.

[0072] b) Polythiol compounds

[0073] The composition of the present invention comprises b) at least one polythiol compound. In this context, the molar ratio of thiol (-SH) groups to (meth)acrylate groups is in the range of 0.5:1 to 1:1, for example in the range of 0.6:1 to 1:1 or 0.8:1 to 1:1. It should be noted that the molar ratio is defined by reference to the total amount of methacrylate and acrylate groups present in the composition: although the epoxy methacrylate compound is an essential component of the composition, the presence of additional reactive compounds carrying acrylate or methacrylate groups is not excluded.

[0074] Within this molar ratio condition, based on the weight of the composition, the composition comprises 10-80 wt.% of b) at least one polythiol compound. For example, based on the weight of the composition, the composition may comprise 20-60 wt.%, preferably 20-50 wt.% of b) at least one polythiol compound.

[0075] In a preferred embodiment, the or each polythiol compound contained in the composition should have 2 to 5 thiol groups, such as 2 to 4 thiol groups. Independently of or in addition to this functionality condition, it is preferred that the or each polythiol compound contained in the composition should have a weight average molecular weight (Mw) of less than 20,000 Daltons, such as less than 5000 Daltons and preferably 200 to 800 Daltons.

[0076] Suitable thiol group-containing compounds that may be used alone or in combination include, but are not limited to, the following:

[0077] Liquid thiol (SH) terminated polysulfide polymers, commercially available examples of which include: polymers (which are available from Morton Thiokol), in particular types LP-3, LP-33, LP-980, LP-23, LP-55, LP-56, LP-12, LP-31, LP-32 and LP-2; and Polymers available from Akzo Nobel, in particular types G10, G112, G131, G1, G12, G21, G22, G44 and G4 thereof.

[0078] - Thiol (SH)-terminated polyoxyalkylene ethers, which can be obtained by reacting polyoxyalkylene diols and triols with epichlorohydrin or alkylene oxides, followed by reaction with sodium hydrosulfide.

[0079] Thiol (SH)-terminated compounds in the form of polyoxyalkylene derivatives, which are marketed under the trade name (from Cognis), in particular its WR-8, LOF and 3-800 models.

[0080] Polyesters of thiocarboxylic acids, such as mercaptoacetic acid (thioglycolic acid), mercaptopropionic acid, mercaptobenzoic acid and mercaptosuccinic acid. Specific examples of such polyesters include: pentaerythritol tetrakis mercaptoacetate; pentaerythritol tetrakis (3-mercaptopropionate); trimethylolpropane trimercaptoacetate (TMPMP); ethylene glycol dimercaptoacetate; and esterification products of polyoxyalkylene diols and triols, ethoxylated trimethylolpropane and polyester diols with thiocarboxylic acids, such as mercaptoacetic acid and 2- or 3-mercaptopropionic acid.

[0081] 2,4,6-Trimercapto-1,3,5-triazine, 2,2′-(ethylenedioxy)-diethanethiol (triethylene glycol dithiol) and / or ethanedithiol.

[0082] Tris(2-(mercaptopropionyloxy)ethyl)isocyanate.

[0083] Preferably, polyesters of thiocarboxylic acids are used, in particular at least one of pentaerythritol tetrathioglycolate, pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate), trimethylolpropane trimercaptoacetate (TMPMP), tris (2-(mercaptopropionyloxy) ethyl) isocyanate and ethylene glycol dimercaptoacetate.

[0084] c) Ethylenically unsaturated monomers

[0085] The composition of the present disclosure comprises 0 to 50 wt.% of at least one ethylenically unsaturated monomer, based on the weight of the composition. Preferably, the composition comprises 0 to 30 wt.%, for example 0 to 20 wt.%, of the at least one ethylenically unsaturated monomer. In principle, such monomers can be any ethylenically unsaturated monomer. However, the present invention is particularly suitable for compositions in which the (meth)acrylate monomers account for at least 60 wt.%, preferably at least 75 wt.%, of the total amount of ethylenically unsaturated monomers present in the composition.

[0086] c) i) (Meth)acrylate monomers

[0087] There is no particular intention to limit the (meth)acrylates used herein, and it is contemplated that the (meth)acrylate monomers may be any ester of acrylic acid or methacrylic acid known in the art. That is, exemplary (meth)acrylic monomers include, but are not limited to:

[0088] ·(Meth)acrylic acid C1-C 18 Alkyl esters, for example methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate (all isomers), hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate,

[0089] n-Decyl (meth)acrylate, n-Dodecyl (meth)acrylate, and n-Stearyl (meth)acrylate;

[0090] ·(Meth)acrylic acid C3-C 18 Cycloalkyl esters, for example cyclohexyl (meth)acrylate and isobornyl (meth)acrylate;

[0091] ·(Meth)acrylic acid C6-C18 Aryl esters, such as phenyl (meth)acrylate and toluene (meth)acrylate;

[0092] ·(Meth)acrylic acid C7-C 24 Aralkyl esters, for example benzyl (meth)acrylate;

[0093] ·(Meth)acrylic acid C1-C 18 Alkoxyalkyl esters, for example 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate and 3-methoxybutyl (meth)acrylate;

[0094] · Fluorinated C1-C 18 Alkyl esters, for example trifluoromethyl methyl (meth)acrylate, 2-trifluoromethyl ethyl (meth)acrylate, 2-perfluoroethyl ethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutyl ethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, perfluoromethyl (meth)acrylate, diperfluoromethyl methyl (meth)acrylate, 2-perfluoromethyl-2-perfluoroethyl methyl (meth)acrylate, 2-perfluorohexyl ethyl (meth)acrylate, 2-perfluorodecyl ethyl (meth)acrylate and 2-perfluorohexadecyl ethyl (meth)acrylate;

[0095] ·(Meth)acrylic acid C1-C 18 Hydroxyalkyl esters, in particular C1-C6 hydroxyalkyl (meth)acrylic acid esters, for example 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate and pentaerythritol tri(meth)acrylate;

[0096] Di- / polyfunctional alcohol diesters / polyesters, such as ethylene glycol di(meth)acrylate, 1,3 or 1,4-butanediol di(meth)acrylate,

[0097] 1,6-Hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate; ethoxylated trimethylolpropane triacrylate; trimethylolpropane trimethacrylate; dipentaerythritol monohydroxypentaacrylate; pentaerythritol triacrylate; neopentyl glycol diacrylate; pentaerythritol tetraacrylate; 1,2-butylene glycol diacrylate; trimethylolpropane ethoxylate tri(meth)acrylate; glyceryl propoxylate tri(meth)acrylate; tripropylene glycol di(meth)acrylate

[0098] acrylates; neopentyl glycol propoxylate di(meth)acrylate; triethylene glycol di(meth)acrylate; and butanediol di(meth)acrylate.

[0099] ·(Meth)acrylic acid C1-C 18Aminoalkyl esters, for example 2-aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate and (meth)acryloyloxyethoxyethylamine;

[0100] ·(Meth)acrylic acid containing C1-C 18 Alkyl esters of alkoxysilyl groups, for example γ-(methacryloxypropyl)trimethoxysilane;

[0101] (Meth)acrylates formed from alcohols with other functional groups, such as tetrahydrofurfuryl (meth)acrylate; and

[0102] (Meth)acrylates of other bio-based monohydric alcohol or polyol compounds, including, but not limited to: (meth)acryloyl-L-lysine; epoxidized soybean oil (meth)acrylate; sugar-derived (meth)acrylates, such as Ecomer available from Ecosynthetix; cardanol-derived (meth)acrylates, such as the NX-7202 to NX-7207 series available from Cardolite; and vegetable oil-derived (meth)acrylates, such as MERCRYL available from HOBUM Oleochemicals.

[0103] In a preferred expression that is not intended to be mutually exclusive with the above-described classes of (meth)acrylate monomers, the composition may include at least one (meth)acrylate monomer represented by Formula M:

[0104] H2C=CQCO2R 1 (M)

[0105] wherein: Q is hydrogen, halogen or C1 alkyl; and

[0106] R 1 It is C1-C 18 Alkyl, C1-C 18 Hydroxyalkyl, C3-C 18 Cycloalkyl, C3-C5 cycloalkyl, C1-C3 alkyl, C2-C5 heterocycloalkyl, C2-C5 heterocycloalkyl, C1-C3 alkyl, C2-C 20 Alkenyl, C2-C 12 Alkynyl, C6-C 18 Aryl, C1-C9 heteroaryl, C1-C9 heteroaryl C1-C3 alkyl, C7-C 24 Alkyl or C7-C 24 Aralkyl.

[0107] Preferably, R in Formula M 1 It is C1-C 12 Alkyl, C1-C 12 Hydroxyalkyl, C3-C 12Cycloalkyl, C3-C5 cycloalkyl, C1-C3 alkyl, C2-C5 heterocycloalkyl, C2-C5 heterocycloalkyl, C1-C3 alkyl, C6-C 18 Aryl, C1-C9 heteroaryl, C1-C9 heteroaryl C1-C3 alkyl, C7-C 18 Alkyl and C7-C 18 Aralkyl. Among them, R 1 It is C1-C 12 Alkyl, C1-C 12 Hydroxyalkyl, C3-C 12 The embodiments of cycloalkyl, C3-C5cycloalkylC1-C3alkylC2-C5heterocycloalkyl or C2-C5heterocycloalkylC1-C3alkyl.

[0108] For the sake of completeness, exemplary (meth)acrylic acids C1-C 12 The alkyl esters include: methyl (meth)acrylate; ethyl (meth)acrylate; n-propyl (meth)acrylate; isopropyl (meth)acrylate; n-butyl (meth)acrylate; isobutyl (meth)acrylate; tert-butyl (meth)acrylate; n-pentyl (meth)acrylate; n-hexyl (meth)acrylate; n-heptyl (meth)acrylate; n-octyl (meth)acrylate; 2-ethylhexyl (meth)acrylate; nonyl (meth)acrylate; decyl (meth)acrylate; dodecyl (meth)acrylate esters; trifluoromethyl methyl (meth)acrylate; 2-trifluoromethyl ethyl (meth)acrylate; 2-perfluoroethyl ethyl (meth)acrylate; 2-perfluoroethyl-2-perfluorobutyl ethyl (meth)acrylate; 2-perfluoroethyl (meth)acrylate; perfluoromethyl (meth)acrylate; diperfluoromethyl methyl (meth)acrylate; 2-perfluoromethyl-2-perfluoroethyl methyl (meth)acrylate; 2-perfluorohexyl ethyl (meth)acrylate; and 2-perfluorodecyl ethyl (meth)acrylate. Exemplary C1-C1 (meth)acrylates 12 Hydroxyalkyl esters include: 2-hydroxyethyl (meth)acrylate; and 2-hydroxypropyl (meth)acrylate. Exemplary C3-C 12 Cycloalkyl esters include: cyclohexyl (meth)acrylate; isobornyl (meth)acrylate; and norbornyl (meth)acrylate.

[0109] In addition, it is not excluded that component c) of the composition comprises a macromer component consisting of one or more oligomers selected from the group consisting of urethane (meth) acrylates, polyester (meth) acrylates; polyether (meth) acrylates; and copolymers of (meth) acrylate functional polymers and conjugated dienes. However, such oligomeric compounds, which may be monofunctional or polyfunctional with respect to the polymerizable (meth) acrylate functional group, but which are based on a repeating structure of urethane, ester, ether and hydrocarbon subunits, should generally not exceed 30 wt.% of the total amount of (meth) acrylate monomers in the composition.

[0110] As known in the art, urethane (meth) acrylate oligomers can be prepared by reacting a multifunctional (meth) acrylate with a hydroxyl group with a polyisocyanate as defined above. In particular, the multifunctional (meth) acrylate with a hydroxyl group can be selected from: 2-hydroxyethyl (meth) acrylate; 2-hydroxyisopropyl (meth) acrylate; 4-hydroxybutyl (meth) acrylate; hydroxyethyl caprolactone (meth) acrylate; pentaerythritol tri(meth) acrylate; pentaerythritol tetra(meth) acrylate; dipentaerythritol penta(meth) acrylate; dipentaerythritol (meth) acrylate; and combinations thereof.

[0111] Suitable polyester (meth)acrylate oligomers are obtained by reacting (meth)acrylic acid with a polyester prepared from a polyacid or its anhydride and a polyol. Examples of polyacids include, but are not limited to, phthalic acid; succinic acid; adipic acid; glutaric acid; sebacic acid; isosebacic acid; tetrahydrophthalic acid; hexahydrophthalic acid; 2,4- or 2,5-furandicarboxylic acid; dimer acid; trimellitic acid; pyromellitic acid; pimelic acid; and azelaic acid. Examples of polyols include, but are not limited to, 1,4-butanediol; 1,6-hexanediol; diethylene glycol; 1,2-propylene glycol; 1,3-butylene glycol; neopentyl glycol; dipropylene glycol; polyethylene glycol; and polypropylene glycol.

[0112] As known in the art, polyether (meth) acrylate oligomers can be obtained by transesterification between polyethers and (meth) acrylates (e.g., ethyl methacrylate). Exemplary polyethers include polyethers obtained from ethoxylated or propoxylated trimethylolpropane, pentaerythritol, etc., or polyethers obtained by polyetherification of 1,3-propylene glycol, etc.

[0113] In an exemplary embodiment, component c) may comprise or consist of at least one (meth)acrylate corresponding to formula (O):

[0114]

[0115] Where: R 4is hydrogen, C1-C4 alkyl or

[0116]

[0117] R 5 is hydrogen, halogen or C1 alkyl;

[0118] R 6 is hydrogen, hydroxyl or

[0119]

[0120] m is an integer ≥ 1, preferably 1 to 8;

[0121] v is 0 or 1; and

[0122] n is an integer ≥3, preferably 3 to 30.

[0123] Among such polyether (meth)acrylates of formula O, mention may in particular be made of poly(ethylene glycol) di(meth)acrylates having the following structure:

[0124]

[0125] Wherein: n≥3, preferably 3-30, more preferably 3-20.

[0126] Thus, specific examples include, but are not limited to: PEG 200 DMA (n≈4); PEG 400 DMA (n≈9); PEG 600 DMA (n≈14); and PEG 800 DMA (n≈19), where the designated number (eg, 400) represents the weight average molecular weight of the diol portion of the molecule.

[0127] Other exemplary oligomeric (meth) acrylates include hydrogenated polybutadiene di(meth) acrylate or hydrogenated polyisoprene di(meth) acrylate. Typically, these compounds are synthesized according to one of the following mechanisms: esterification reaction of hydrogenated polybutadiene polyol or hydrogenated polyisoprene polyol with (meth) acrylic acid; transesterification reaction of hydrogenated polybutadiene polyol or hydrogenated polyisoprene polyol with (meth) acrylate; addition reaction of hydrogenated polybutadiene polyol or hydrogenated polyisoprene polyol with isocyanate-containing (meth) acrylate; or addition reaction of hydrogenated polybutadiene polyol or hydrogenated polyisoprene polyol, polyisocyanate and (meth) acrylate containing alcoholic hydroxyl group. Hydrogenated polybutadiene (meth) acrylate and hydrogenated polyisoprene (meth) acrylate are also available as commercial products, such as NISSO-PB TEAI-1000 manufactured by NipponSoda Co., Ltd.

[0128] It is known in the art that the introduction of certain additional non-polymeric functional groups into (meth)acrylate monomers can improve the surface adhesion of the polymers derived therefrom. Mention may be made in this regard of anhydride, phosphate or phosphonate functional groups, and (meth)acrylate monomers carrying such functional groups may be used in component a) i) of the composition of the invention. Exemplary monomers include: monomethacryloyloxyethyl phosphate; bis(2-methacryloyloxyethyl)phosphate; 10-[(2-methylprop-2-enoyl)oxy]decyl dihydrogen phosphate (10-methacryloyloxydecyl dihydrogen phosphate); and 4-methacryloyloxyethyl trimellitic anhydride.

[0129] c) ii) Copolymerizable acid

[0130] The composition may optionally contain at least one copolymerizable acid. When used, the acid may be added in an amount of up to 40 wt.%, for example up to 25 wt.%, of the total amount of ethylenically unsaturated monomers present. Thus, the at least one copolymerizable acid may constitute 0 to 15 wt.% of the total molar amount of ethylenically unsaturated monomers. For the sake of completeness, although such monomers should generally be used in the form of free acids, it is not excluded that the constituent acid groups of the monomers are partially or completely neutralized by a suitable base, as long as this does not affect their participation in the copolymerization.

[0131] Without intending to limit the invention, the copolymerizable acid monomer should be selected from: ethylenically unsaturated carboxylic acids; ethylenically unsaturated sulfonic acids; and vinylphosphonic acid. Suitable ethylenically unsaturated sulfonic acids are, for example, vinylsulfonic acid, styrenesulfonic acid and acrylamidomethylpropanesulfonic acid.

[0132] Preferably, the at least one copolymerizable acid of the composition comprises or consists of an ethylenically unsaturated carboxylic acid selected from the group consisting of α,β-monoethylenically unsaturated monocarboxylic acids; α,β-monoethylenically unsaturated dicarboxylic acids; C1-C6 alkyl half esters of α,β-monoethylenically unsaturated dicarboxylic acids; α,β-monoethylenically unsaturated tricarboxylic acids; and C1-C6 alkyl esters of α,β-monoethylenically unsaturated tricarboxylic acids with at least one free carboxylic acid group; and mixtures thereof. In particular, the at least one copolymerizable acid of the composition comprises or consists of an ethylenically unsaturated carboxylic acid selected from the group consisting of methacrylic acid; acrylic acid; itaconic acid; maleic acid; aconitic acid; crotonic acid; fumaric acid; and mixtures thereof.

[0133] c) iii) Additional monomers

[0134] It should be noted that the present invention does not exclude the presence of a vinyl monomer copolymerizable with the (meth)acrylate monomer in the composition, the vinyl monomer being selected from: styrene monomers, such as styrene, vinyl toluene, α-methylstyrene and chlorostyrene; fluorine-containing vinyl monomers, such as perfluoroethylene, perfluoropropylene and fluorinated vinylidene; silicon-containing vinyl monomers, such as vinyl trimethoxysilane and vinyl triethoxysilane; maleimide monomers, such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide , hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide and cyclohexylmaleimide; nitrile-containing vinyl monomers such as acrylonitrile and methacrylonitrile; amide-containing vinyl monomers such as acrylamide and methacrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate and vinyl cinnamate; olefins such as ethylene and propylene; conjugated dienes such as butadiene and isoprene; and vinyl chloride, vinylidene chloride, allyl chloride and allyl alcohol.

[0135] Additives and auxiliary ingredients

[0136] The compositions obtained in the present invention also typically contain adjuvants and additives that can impart improved properties to these compositions. For example, the adjuvants and additives can impart one or more of the following properties: improved elasticity; increased elastic recovery; enabled processing time (enabled processing time) longer; faster curing time; and lower residual viscosity. These adjuvants and additives include: catalysts; plasticizers; stabilizers, including UV stabilizers; antioxidants; reactive diluents; non-reactive diluents; desiccants; adhesion promoters; bactericides; flame retardants; rheological additives; fillers; and coloring pigments or pastes.

[0137] These adjuvants and additives can be used in desired combinations and proportions, as long as they do not adversely affect the properties and basic performance of the composition. Although there may be exceptions in some cases, the total amount of these adjuvants and additives should not exceed 50wt.% of the total composition, preferably should not exceed 20wt.% of the composition.

[0138] The composition of the present invention may optionally include a Michael addition catalyst, which refers herein to a compound capable of promoting a Michael addition reaction between a polythiol compound and a compound having a (meth) acrylic group. Typically, Michael addition catalysts include amine catalysts, base catalysts, and organometallic catalysts, which can be used alone or in combination. Exemplary amine catalysts include: proline; triazabicyclodecene (TBD); diazabicycloundecene (DBU); hexahydromethylpyrimidopyridine (MTBD); diazabicyclononane (DBN); tetramethylguanidine (TMG); and triethylenediamine (TEDA). Examples of base catalysts include: sodium methoxide; sodium ethoxide; potassium tert-butoxide; potassium hydroxide; sodium hydroxide; metallic sodium; lithium diisopropylamide (LDA); and butyl lithium. Exemplary organometallic catalysts include: ruthenium catalysts, such as (cyclooctadiene)(cyclooctatriene)ruthenium and ruthenium hydride; iron catalysts, such as iron (III) chloride and iron acetylacetonate; nickel catalysts, such as nickel acetylacetonate, nickel acetate, nickel salicylaldehyde; copper catalysts; palladium catalysts; scandium catalysts; lanthanide catalysts; ytterbium catalysts; and tin catalysts.

[0139] The Michael addition catalyst may be used herein in an amount of 0-5 wt%, for example 0-2 wt%, based on the weight of the composition. However, it is repeated that such Michael addition catalyst need not be present in the composition, and indeed, in a preferred embodiment, the composition is substantially free of Michael addition catalyst.

[0140] "Plasticizer" for the purposes of the present invention refers to a substance that reduces the viscosity of the composition and thus promotes its processability. In this context, the plasticizer may represent 0-10 wt.% or 0-5 wt.%, based on the total weight of the composition. When present, the plasticizer is preferably selected from: diurethanes; ethers of monofunctional linear or branched C4-C16 alcohols, such as Cetiol OE (available from Cognis Deutschland GmbH, Düsseldorf); esters of rosin acid, butyric acid, thiobutyric acid, acetic acid, propionic acid and citric acid; esters based on nitrocellulose and polyvinyl acetate; fatty acid esters; dicarboxylates; esters of fatty acids with hydroxyl groups; glycolates; benzoates; phosphates; sulfonates; trimellitates; polyether plasticizers, such as end-capped polyethylene glycol or polypropylene glycol; polystyrene; hydrocarbon plasticizers; chlorinated paraffins; and mixtures thereof. It should be noted that, in principle, phthalates can be used as plasticizers, but these are not preferred due to their potential toxicity.

[0141] "Stabilizer" for the purposes of the present invention is understood to be an antioxidant, UV stabilizer, heat stabilizer or hydrolysis stabilizer. In this context, plasticizers may account for a total of 0-10 wt.% or 0-5 wt.%, based on the total weight of the composition. Standard commercial examples of stabilizers suitable for use herein include: sterically hindered phenols; thioethers; benzotriazoles; benzophenones; benzoates; cyanoacrylates; acrylates; amines of the hindered amine light stabilizer (HALS) type; phosphorus; sulfur; and mixtures thereof.

[0142] The composition of the present disclosure may contain a particulate filler. The desired viscosity of the curable composition formed may be determined by the amount of filler used. Taking the latter into account, the total amount of filler should not prevent the composition from being easily applied to the substrate by the selected composition application method. For example, the composition of the present invention intended to be applied to a specific location by printing or injection should have a viscosity of 1000 to 50000 mPa.s, preferably 10000 to 40000 mPa.s.

[0143] In a broad sense, there is no particular intention to limit the shape of the particles used as fillers: needle-shaped, spherical, ellipsoidal, cylindrical, bead-shaped, cubic or plate-shaped particles can be used alone or in combination. In addition, it is envisaged that agglomerates of more than one particle type can be used. Likewise, there is no particular intention to limit the particle size of the particles used as fillers. However, such fillers typically have an average particle size (d50) of 0.1-1000 μm, for example 1-500 μm, the average particle size being measured by laser diffraction / scattering methods.

[0144] Exemplary fillers include, but are not limited to, graphite, carbon black, calcium carbonate, calcium oxide, calcium chloride, calcium hydroxide (lime powder), calcium sulfate, fused silica, amorphous silica, precipitated and / or pyrolyzed silicic acid, zeolite, bentonite, wollastonite, magnesium carbonate, magnesium sulfate, diatomaceous earth, barium sulfate, barium oxide, aluminum oxide, aluminum nitride, boron nitride, clay, talc, titanium oxide, iron oxide, zinc oxide, sand, quartz, flint, mica, glass beads, glass powder and other ground minerals. Organic fillers may also be used, particularly wood fiber, wood powder, sawdust, cellulose, cotton, pulp, cotton, wood chips, chopped straw, husks, ground walnut shells and other chopped fibers: poly(tetrachloroethylene), poly(chlorotrifluoroethylene) and poly(vinylidene chloride) powders may also be used. Short fibers may also be added, such as glass fibers, glass filaments, polyacrylonitrile, carbon fibers, Kevlar fibers or polyethylene fibers.

[0145] Also suitable as fillers are hollow spheres with a mineral or plastic shell. These can be, for example, marketed under the trade name Glass Commercially available hollow glass spheres. Plastic based hollow spheres may be used, e.g. or And they are described in EP 0 520 426 B1: They consist of inorganic or organic substances and each have a diameter of 1 mm or less, preferably 500 μm or less.

[0146] The use of core-shell rubber particles as fillers is also not excluded. The term "core-shell rubber" or CSR is used according to its standard meaning in the art to represent a rubber particle core formed by a polymer comprising an elastomer or rubbery polymer as a main component and a shell formed by a polymer graft polymerized onto the core. The shell partially or completely covers the surface of the rubber particle core during the graft polymerization process. By weight, the core should constitute at least 50wt.% of the core-shell rubber particle.

[0147] The core-shell rubber may be selected from commercially available products, examples of which include: Paraloid TMS-2670J, EXL 2650A, EXL 2655 and EXL2691A, which are available from The Dow Chemical Company; XT100, which is available from Arkema Inc.; Kane MX series (available from Kaneka Corporation), in particular MX 120, MX 125, MX 130, MX 136, MX 551, MX 553; and METABLEN SX-006, available from Mitsubishi Rayon.

[0148] Fillers which impart thixotropy to the composition may be preferred for many applications: such fillers are also described as rheology aids, for example hydrogenated castor oil, fatty acid amides or swellable plastics such as PVC.

[0149] It should be noted that compounds having metal chelating properties can be used in the compositions of the present invention to help enhance the adhesion of the cured adhesive to the substrate surface. Also suitable for use as an adhesion promoter is the acetoacetate functionalized modified resin sold by King Industries under the trade name K-FLEX XM-B301.

[0150] In order to further extend the shelf life, it is generally recommended to further stabilize the composition of the invention with respect to moisture penetration by using a desiccant. It is sometimes also necessary to reduce the viscosity of the adhesive or sealant composition of the invention for a particular application by using a reactive diluent. The total amount of reactive diluent present is typically 0-10 wt.%, e.g. 0-5 wt.%, based on the total weight of the composition.

[0151] The presence of solvents and non-reactive diluents is not excluded in the composition of the invention, in which case this can be effective in adjusting its viscosity. For example, and by way of example only, the composition may contain one or more of the following: xylene; 2-methoxyethanol; dimethoxyethanol; 2-ethoxyethanol; 2-propoxyethanol; 2-isopropoxyethanol; 2-butoxyethanol; 2-phenoxyethanol; 2-benzyloxyethanol; benzyl alcohol; ethylene glycol; ethylene glycol dimethyl ether; ethylene glycol diethyl ether; ethylene glycol dibutyl ether; ethylene glycol diphenyl ether; diethylene glycol; diethylene glycol monomethyl ether; diethylene glycol monoethyl ether; diethylene glycol mono-n-butyl ether; diethylene glycol dimethyl ether; diethylene glycol diethyl ether; diethylene glycol di-n-butyl ether; propylene glycol butyl ether; propylene glycol phenyl ether; dipropylene glycol; dipropylene glycol monomethyl ether; dipropylene glycol dimethyl ether; dipropylene glycol di-n-butyl ether; N-methylpyrrolidone; diphenylmethane; diisopropylnaphthalene; petroleum fractions, such as products (which are available from Exxon); alkylphenols, such as tert-butylphenol, nonylphenol, dodecylphenol and 8,11,14-pentadecatrienylphenol; styrenated phenols; bisphenols; aromatic hydrocarbon resins, especially those containing phenolic groups, such as ethoxylated or propoxylated phenols; adipates; sebacates; phthalates; benzoates; organic phosphates or sulfonates; and sulfonamides.

[0152] In addition to the above, it is preferred that the non-reactive diluents total less than 10 wt.%, particularly less than 5 wt.% or less than 2 wt.%, based on the total weight of the composition.

[0153] Methods and Administration

[0154] To form the defined curable composition, the components are brought together and mixed. It is important that the mixing be uniform to distribute the ingredients throughout the composition: such thorough and efficient mixing will determine the uniform distribution of any constituent particulate fillers or other auxiliary materials throughout the resulting polymer matrix after curing.

[0155] As is known in the art, to form a one-component (1K) curable composition, the components of the composition are brought together and uniformly mixed under conditions that inhibit or prevent the reaction of the reactive components: such conditions are readily understood by those skilled in the art. Therefore, it is generally preferred that the curing components are not mixed manually, but are mixed in predetermined amounts by a machine (e.g., a static or dynamic mixer) without intentional light radiation or heating.

[0156] According to the broadest process aspect of the invention, the above-described composition is applied to a substrate and then cured in situ. Before applying the composition, it is generally advisable to pre-treat the relevant substrate surface to remove impurities therefrom: if applicable, this step can promote the subsequent adhesion of the composition thereto. Such treatments are known in the art and can be carried out in a single-stage or multi-stage manner, which consists, for example, of using one or more of the following treatments: etching treatment with an acid suitable for the substrate and optionally an oxidizing agent; ultrasonic treatment; plasma treatment, including chemical plasma treatment, corona treatment, atmospheric pressure plasma treatment and flame plasma treatment; immersion in an aqueous alkaline degreasing bath; treatment with an aqueous cleaning emulsion; treatment with a cleaning solvent, such as acetone, carbon tetrachloride or trichloroethylene; and water rinsing, preferably using deionized water or demineralized water.

[0157] In some embodiments, the adhesion of the composition of the present invention to the preferably pretreated substrate can be promoted by applying a primer thereto. In fact, a primer composition may be necessary to ensure effective fixation and / or curing time of the composition on the inactive substrate. Those skilled in the art will be able to select a suitable primer.

[0158] The composition is then applied to the optionally pretreated, optionally primed substrate surface by conventional application methods, such as brushing; roller coating; blade application; spraying methods, including but not limited to air atomization spraying, air-assisted spraying, airless spraying and high-volume low-pressure spraying; printing methods, including screen printing; pin transfer; and syringe application, including electro-pneumatic control syringes. It is recommended that the composition be applied to the surface with a wet film thickness of 10-500 μm. Applying thinner layers within this range is more economical and reduces the possibility of producing harmful thick cured areas. However, strict control must be carried out when applying thinner coatings or layers to avoid the formation of discontinuous cured films.

[0159] In the case where the composition is to be photo-chemically cured, the energy source used to initiate curing of the applied composition will emit at least one of ultraviolet (UV) radiation, infrared (IR) radiation, visible light, X-rays, gamma rays, or electron beams (e-beams). After their application, the composition can typically be activated in less than 5 minutes, typically in 1 to 60 seconds, such as 3 to 12 seconds, when irradiated using commercially available curing equipment.

[0160] The irradiation ultraviolet light should generally have a wavelength of 150 to 600 nm, preferably 200 to 450 nm. Available UV light sources include, for example, ultra-high pressure mercury lamps, high pressure mercury lamps, medium pressure mercury lamps, low intensity fluorescent lamps, metal halide lamps, microwave lamps, xenon lamps, UV-LED lamps and laser beam sources, such as excimer lasers and argon ion lasers.

[0161] In the case of using an electron beam to cure the applied composition, standard parameters for operating the device may be: an accelerating voltage of 0.1-100 keV; a -3 Pa of vacuum; 0.0001 to 1 ampere of current; and 0.1 watt to 1 kilowatt of power.

[0162] The amount of radiation required to sufficiently cure a single composition, e.g., so that a coating thereof becomes fixed, will depend on a number of factors, including the angle of exposure to the radiation and the thickness of the applied composition. However, in broad terms, 5 to 5000 mJ / cm 2 The curing dose can be considered typical: 50 to 500mJ / cm 2 The curing dose is, for example, 50 to 400 mJ / cm 2 A curing dose of can be considered highly effective.

[0163] Cure chemistry under light exposure follows the same thermodynamic rules as any chemical reaction: the reaction rate can be accelerated by heating, or slowed by lowering the temperature. In the event that shadow areas exist on a substrate to which the composition has been applied, the temperature of the substrate can be raised above ambient temperature after light exposure to ensure complete shadow cure.

[0164] Without intending to limit the invention, thermal curing of the applied curable composition should generally occur at a temperature of 50°C to 200°C, preferably 75°C to 175°C or 100°C to 150°C. Where applicable, conventional methods (including microwave induction) may be used to raise the temperature of the curable composition above the mixing temperature and / or application temperature. The elevated temperature may be maintained for up to 60 minutes to ensure complete curing.

[0165] For the sake of completeness, exemplary substrates to which the compositions of the present invention may be applied include: non-ferrous metal substrates, such as aluminum, zinc and their alloys; ferrous metals, including iron, stainless steel, cold-rolled steel and electrogalvanized steel; engineering plastics; thermoplastic materials, such as polyolefins, among which polyethylene (PE) and polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) may be mentioned; paper; cardboard; glass; composite materials; wood; leather; and combinations thereof.

[0166] It is contemplated that the compositions of the present invention may be used as coatings, adhesives and sealants or in the formation of composite structures.

[0167] The following examples are illustrative of the present invention and are not intended to limit the scope of the invention in any way.

[0168] Example

[0169] The following materials are used in the examples:

[0170] Epoxyester 3000MK: dimethacrylate of bisphenol A glycidyl ether (CAS No. 1565-94-2), which is available from Kyoeisha Chemical Co. Ltd.

[0171] PEMP: pentaerythritol tetrakis(3-mercaptopropionate) (CAS No. 7575-23-7), which can be obtained from SC Organic Chemical Co. Ltd.

[0172] Karenz MT PE1: pentaerythritol tetrakis(3-mercaptobutyrate) (CAS No. 31775-89-0), which is available from ShowaDenko.

[0173] Examples 1 to 2

[0174] The compositions were prepared according to the following Table 1. The given ingredients were mixed in a high speed mixer (1200 rpm; 1 minute) to ensure a homogeneous mixture.

[0175] Table 1

[0176]

[0177] The following tests were performed on the exemplary compositions.

[0178] Viscosity : Viscosity was measured using a HAAKE RheoStress 3000 viscometer at 25°C and 50% relative humidity (RH).

[0179] Applicable period : This term is equal to the time that a formulation can be stored without gelling and is determined here by observing the viscosity of the composition at 24 hour intervals at 25°C. The reported pot life is the time required for the viscosity to double (2x) from its initial value, measured after mixing the ingredients.

[0180] UV fixed time : Test samples were prepared manually by placing a small drop of the composition on a clean, dry microscope slide (76×26×1 mm) at room temperature. A second glass slide was bonded to the first glass slide at an angle of 30° to 90°. The sample was then cured under a high pressure mercury lamp that provided 100 mW / cm 2The energy of the light source was 1000 nm with a short wavelength output having peaks at 254 nm and 365 nm. The light source was applied at intervals of 4 to 5 seconds, and a shear torque was applied to the slides by hand after the curing interval. The fixation time (seconds) was determined when the assembly supported the shear torque without relative motion of the two slides.

[0181] Surface curing (UV) The composition was applied to a non-stick glass slide and cured under a high pressure mercury lamp providing 100 mW / cm 2 The energy was a short wavelength output with peaks at 254 nm and 365 nm. The light source was applied at 5 second intervals over a period of 60 seconds.

[0182] Gel time : According to ASTM specification D-3451, a piece of aluminum foil is placed on a hot plate and heated to a temperature of 120°C. A small amount of the composition is dropped onto the heated foil and tapped with a tongue depressor until a continuous and brittle filament is formed when the tongue depressor is lifted from the foil. The elapsed time in seconds for this to occur is measured.

[0183] Heat curing : The composition was thermally cured by heating the sample at 120°C for 60 minutes.

[0184] The results and observations from these tests are recorded in Table 2 below.

[0185] Table 2

[0186]

[0187] In view of the foregoing description and examples, it will be apparent to a person skilled in the art that equivalent modifications may be made thereto without departing from the scope of the claims.

Claims

1. A dual-cure composition that is both heat-curable and light-curable, comprising, based on the weight of the composition: 20 to 90 wt. % of a) at least one epoxy methacrylate compound having at least two methacrylate groups; and 10 to 80 wt.% of b) at least one polythiol compound, The composition is characterized in that the molar ratio of thiol (—SH) groups to (meth)acrylate groups is in the range of 0.5:1 to 1:

1.

2. The dual-cure composition according to claim 1, comprising, based on the weight of the composition: 40 to 80 wt.%, preferably 50 to 80 wt.% of a) at least one epoxy methacrylate compound having at least two methacrylate groups; 20 to 60 wt.%, preferably 20 to 50 wt.% of b) at least one polythiol compound; and, 0 to 50 wt.%, preferably 0 to 30 wt.%, of c) at least one ethylenically unsaturated monomer, The composition described therein is characterized in that the molar ratio of thiol (—SH) groups to (meth)acrylate groups is in the range of 0.6:1 to 1:1, preferably 0.8:1 to 1:

1.

3. The dual-cure composition according to claim 1 or 2, wherein the at least one epoxy methacrylate compound is an adduct of methacrylic acid and a polyepoxide. 4 . The dual-cure composition according to claim 3 , wherein the polyepoxide has an epoxy equivalent weight of 100 to 700 g / eq, preferably 120 to 320 g / eq.

5. The dual-cure composition according to claim 3 or 4, wherein the polyepoxide is selected from the group consisting of polyglycidyl ethers of polyhydric alcohols, polyglycidyl ethers of polyhydric phenols, polyglycidyl esters of polycarboxylic acids, and epoxidized polyethylenically unsaturated hydrocarbons.

6. The dual-cure composition according to any one of claims 3 to 5, wherein the polyepoxide is a diglycidyl ether selected from the group consisting of diglycidyl ethers of aliphatic and alicyclic diols, diglycidyl ethers based on bisphenol A, diglycidyl ethers based on bisphenol F, diglycidyl ethers based on polyalkylene glycols, and glycidyl ethers based on polycarbonate diols.

7. A dual cure composition according to any one of claims 1 to 6, wherein the or each polythiol compound contained in the composition has 2 to 5 thiol groups.

8. A dual cure composition according to any one of claims 1 to 7, wherein the or each polythiol compound contained in the composition has a weight average molecular weight (Mw) of less than 20,000 Daltons, preferably from 200 to 800 Daltons. 9 . The dual-cure composition according to claim 1 , wherein component b) comprises or consists of at least one polyester of a thiocarboxylic acid.

10. The dual-cure composition according to claim 9, wherein component b) comprises or consists of at least one compound selected from the group consisting of: Pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), trimethylolpropane trimercaptoacetate (TMPMP), tris(2-(mercaptopropionyloxy)ethyl)isocyanate, and ethylene glycol dimercaptoacetate.

11. The dual-cure composition according to any one of claims 2 to 10, comprising 5 to 30 wt.% of c) at least one ethylenically unsaturated monomer.

12. The dual-cure composition according to any one of claims 2 to 11, wherein the (meth)acrylate monomers constitute at least 60 wt.%, preferably at least 75 wt.% of the total amount of ethylenically unsaturated monomers present in the composition.

13. The dual-cure composition according to any one of claims 1 to 12, which is substantially free of free radical photoinitiators.

14. The dual cure composition according to any one of claims 1 to 13, which is substantially free of thermal free radical initiators.

15. Use of the dual-cure composition according to any one of claims 1 to 14 as a coating, adhesive or sealant.

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