Copolymers and hot melt compositions containing said copolymers

Abstract

The present application is directed to a copolymer obtained by free radical polymerization, said polymer comprising: 0.01-10% by weight, based on the total weight of monomers, of a) at least one copolymerizable photoinitiator having an ethylenically unsaturated group and a moiety that decomposes under light irradiation to form radicals; 0.01-10% by weight, based on the total weight of monomers, of b) at least one epoxy (meth)acrylate monomer having at least one (meth)acrylate group and at least one epoxide group; and 80-99.98% by weight, of c) at least one ethylenically unsaturated monomer that does not have an epoxide group or a moiety that decomposes under light irradiation to form radicals. The present application is further directed to a material that is crosslinkable under light irradiation, said material comprising: a copolymer as defined above; and at least one ionic photoacid generator (PAG).

Description

[Technical field]

[0001] The present disclosure is directed to a copolymer that is crosslinkable under light irradiation, derived from a monomer having both epoxide and (meth)acrylate functionality; and at least one copolymerizable photoinitiator having an ethylenically unsaturated group and a moiety that decomposes under light irradiation to form a radical. The present disclosure is also directed to a reactive hot melt composition comprising said copolymer. The present disclosure is further directed to a reactive hot melt pressure sensitive adhesive composition that may have utility in the manufacture of tapes, labels and decals. [Background technology]

[0002] As known in the art, non-reactive hot melt compositions (such as non-reactive hot melt adhesive compositions) are formulated to be substantially free of water and solvents and solid at room temperature. The compositions are further formulated to melt or form a fluid state upon application of heat: the composition is applied to a given substrate in this fluid molten form, but recovers to a solid or viscous liquid form after cooling. The phases that form after the composition cools are intended to provide cohesive strength, toughness, and resistance to both creep and heat. However, non-reactive hot melt compositions are thermoplastic and can be repeatedly heated to a fluid state and cooled to a solid or viscous liquid state.

[0003] Curable or reactive hot melt compositions are likewise solid or highly viscous liquids at room temperature that melt to a liquid or fluid state upon application of heat: they are applied to a substrate in this flowing molten form. When cooled again, the composition regains its original shape. The phases that form after the composition has cooled (but before it has cured) are intended to provide initial strength or wet strength. The applied composition is then cured by chemical crosslinking reactions after being exposed to the required curing conditions. Before curing, the composition remains thermoplastic and can be remelted and resolidified, but once cured, the composition no longer has thermoplastic properties. The crosslinked composition is intended to provide cohesive strength, toughness, and resistance to both creep and heat. And, in general, curable hot melt compositions can provide higher strength and heat resistance than non-curable hot melt compositions.

[0004] A hot melt pressure sensitive adhesive composition is a hot melt adhesive that retains the ability to form a usable bond to an adherend under light pressure at room temperature. More specifically, such reactive or non-reactive adhesive compositions exhibit cold flow under finger pressure at room temperature.

[0005] Rapid development of wet strength upon cooling of an applied hot melt composition can be important in commercial operations, as it facilitates processing of the treated substrate. However, rapid curing of an applied reactive hot melt composition is not always desirable, as it can be detrimental to the workability of the applied composition. For example, moisture-curable hot melt compositions can cure under ambient conditions and begin to develop strength immediately after application that makes them difficult to work with on production line equipment downstream of the applicator.

[0006] Thus, it is clear that compositions that crosslink rapidly to provide cured strength have a short service life. However, adhesive compositions that crosslink slowly have a longer service life, but produce lower strength and delay subsequent commercial operations. Thus, there is a constant effort in the art to develop reactive hot melt compositions that have a commercially desirable combination of wet strength, cured strength, and service life.

[0007] Certain authors have focused on reactive hot melt compositions that can be cured under light irradiation, especially under ultraviolet light. Light curing offers great flexibility as a crosslinking method, since the user can determine the location and time at which the light irradiation occurs and can regulate the exposure to that radiation.

[0008] For example, US Patent No. 3,661,618 (Firestone Fire and Rubber Company) provides a composition comprising a polymer such as a cellulose derivative, a polyolefin, or a polyester, a liquid alkyl (meth)acrylate monomer, and a further reactive monomer. After application of the adhesive, the monomer is crosslinked under high-energy particle radiation in the essential absence of oxygen. Problematically, however, the monomeric (meth)acrylate is volatile and irritating. To avoid the drawbacks of having a significant proportion of free monomer in the photocurable composition, the inclusion of copolymers with pendant photoreactive groups has been developed in the art.

[0009] EP 3 252 088 A1 (Henkel AG & Co. KgaA) describes the following: in a first step: (i) a compound of formula (I): [ka] [In the formula, R 1 is H or CH; R 2 and R 3and (ii) a mixture containing at least one monomer containing a pendant reactive functional group selected from an alicyclic epoxide, an oxetane, a monosubstituted oxirane, or a mixture thereof; and in a second step, the mixture obtained from the first step is reacted with (iii) at least one cationic photopolymerization initiator; and (iv) optionally further additives to obtain a UV-curable pressure-sensitive acrylic adhesive.

[0010] WO 2011112643A2 (Henkel Corporation) discloses ultraviolet (UV) crosslinkable acrylic pressure sensitive adhesives comprising a cationic photoinitiator and an acrylic copolymer having pendant reactive functional groups selected from cycloaliphatic epoxides, oxetanes or mixtures thereof.

[0011] EP2960258 A1 (Henkel AG & Co. KgaA) discloses a method for producing a UV-curable acrylic copolymer, the method comprising: (a) polymerizing a mixture of monomers to form an acrylic copolymer, the monomer mixture comprising, based on the weight of the mixture: (i) 40 to 95% by weight of at least one (meth)acrylate monomer; (ii) 5 to 60% by weight of at least one copolymerizable monomer, wherein the monomer is selected from those whose homopolymers have a glass transition temperature higher than -30°C, and iii) optionally 0.5 to 20% by weight of at least one copolymerizable functional monomer having a functional group selected from the group consisting of a hydroxyl group and a carboxyl group; and (b) reacting the acrylic copolymer with at least one monomer comprising a UV-curable functional group in the presence of a catalyst to form a UV-curable acrylic copolymer, wherein the monomer comprising a UV-curable group is a monomer comprising a vinyl group and an epoxy group, preferably an epoxy-functionalized acrylate, more preferably a glycidyl ester of (meth)acrylic acid.

[0012] EP-A-0 017 364 (Rohm & Haas) describes copolymers which may be used, inter alia, in adhesives and sealants, which contain 0.1-10% by weight of allylbenzoylbenzoate as copolymerizing photoinitiator. Although these materials can be crosslinked by the use of UV radiation, it is believed that their reactivity to such radiation is too low, resulting in low curing efficiency, especially at deeper points in the layer of material. Furthermore, it is believed that layers made from the copolymers are not sufficiently tacky for certain adhesive applications.

[0013] The low reactivity and poor efficiency of crosslinked copolymers containing 0.01-5% by weight of copolymerizable 2-alkoxy-2-phenyl-2-benzoylethyl acrylate are also considered drawbacks of the teaching of US Pat. No. 4,144,157 (Beiersdorf AG). [Prior art documents] [Patent documents]

[0014] [Patent Document 1] U.S. Pat. No. 3,661,618 [Patent Document 2] European Patent Application Publication No. 3 252 088 [Patent Document 3] International Application Publication No. 2011112643 [Patent Document 4] European Patent Application Publication No. 2960258 [Patent Document 5] European Patent Application Publication No. 0 017 364 [Patent Document 6] U.S. Patent No. 4,144,157 Summary of the Invention [Problem to be solved by the invention]

[0015] In practice, the low curing efficiency of copolymers containing copolymerizable photoinitiators can be mitigated by using lower coating weights of the hot melt composition or by increasing the dose of radiation applied, however, these solutions may not be desirable or practically feasible in certain applications. [Means for solving the problem]

[0016] According to a first aspect of the present invention, there is provided a copolymer obtainable by free radical polymerization, said copolymer comprising, based on the total weight of monomers: 0.01 to 10% by weight of a) at least one copolymerizable photoinitiator having an ethylenically unsaturated group and a moiety that decomposes under light irradiation to form radicals; 0.01 to 10% by weight of b) at least one epoxy (meth)acrylate monomer having at least one (meth)acrylate group and at least one epoxide group; and 80 to 99.98% by weight of c) at least one ethylenically unsaturated monomer that does not have an epoxide group or a moiety that decomposes under light irradiation to form radicals.

[0017] In an important embodiment, the copolymer comprises, based on the total weight of the monomers, the following: 0.05 to 5% by weight, preferably 0.05 to 2.5% by weight of a) the at least one copolymerizable photoinitiator having an ethylenically unsaturated group and a moiety that decomposes under light irradiation to form radicals; 0.5 to 5% by weight, preferably 0.5 to 2.5% by weight of b) the at least one epoxy (meth)acrylate monomer having at least one (meth)acrylate group and at least one epoxide group; and 90 to 99% by weight, preferably 95 to 99% by weight of c) the at least one ethylenically unsaturated monomer that does not have an epoxide group or a moiety that decomposes under light irradiation to form radicals.

[0018] Typically, the at least one copolymerizable photoinitiator a) has the general formula A-(B) bwhere A represents a substituent having a valence b, including at least one moiety that decomposes under irradiation to form a radical; B represents a moiety that includes an ethylenically unsaturated group; and b is an integer equal to 1 or 2, typically 1. The general formula A-(B) b in which A represents a substituent having a valence b, comprising at least one moiety capable of decomposing under irradiation to form a radical, the or each said moiety comprising a group selected from acetophenone, benzophenone, benzoin, anthraquinone, 9-fluorenone, anthrone, xanthone, thioxanthone, acridone, dibenzosuberone, or chromone; B represents a moiety comprising a (meth)acrylate group or a (meth)acrylamide group; and b is 1 or 2, typically preferably 1.

[0019] Good results have been obtained when the or each polymerizable photoinitiator is benzophenone (meth)acrylate.

[0020] The or each epoxy (meth)acrylate monomer contained in the copolymer is preferably characterized by a total equivalent weight of said epoxide groups and said (meth)acrylate groups of from 100 to 700 g / eq, preferably from 120 to 320 g / eq.

[0021] Conventionally, the or each epoxy (meth)acrylate monomer included in the copolymer is an adduct of (meth)acrylic acid and a polyepoxide compound. Exemplary polyepoxide compounds for forming such adducts may be 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.

[0022] According to a second aspect of the present invention, there is provided a material crosslinkable under light irradiation, said material comprising: a copolymer as defined herein and in the appended claims; and at least one ionic photoacid generator (PAG).

[0023] The present invention further provides a reactive hot melt composition crosslinkable under light irradiation, the composition comprising, based on the weight of the composition: 40-99.99 wt. % of i) at least one copolymer as defined herein and in the appended claims; 0.01-10 wt. % of ii) at least one ionic photoacid generator (PAG); 0-60 wt. % of iii) at least one tackifying resin; and 0-20 wt. % of iv) a wax.

[0024] Such hot melt compositions combine two photocuring mechanisms and are believed to exhibit a combination of important properties. First, the compositions exhibit high thermal stability, especially when cured, compared to standard cationic polymers. Second, such thermal stability is demonstrated even at low coating weights of the hot melt compositions because the hybrid photoinitiator system is efficient and allows through-curing of the compositions. These properties are demonstrated in the examples of the present disclosure. Furthermore, it is noted that the hot melt compositions can be formulated to cure at two different wavelengths, thereby allowing control of the degree of crosslinking in the composition.

[0025] Coatings, adhesives or sealants obtained by crosslinking under light irradiation of a reactive hot melt composition as defined herein above are considered as a further aspect of the invention. Hot melt pressure sensitive adhesive (HMPSA) compositions are an important embodiment of this aspect.

[0026] The present disclosure further provides an article (A) comprising a curable film of the hot melt composition defined above, said film being disposed on a release liner and / or a carrier substrate. The article (A) may be a label, a single-sided tape, a transfer tape or a double-sided tape. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 shows a single-sided tape without a release liner, according to one embodiment of the present invention. [Diagram 2]FIG. 2 shows one embodiment of the article of the present invention corresponding to a single sided tape or label having a release liner. [Diagram 3] FIG. 3 shows a transfer tape having one release liner according to one embodiment of the present invention. [Figure 4] FIG. 4 shows a transfer tape having two release liners according to one embodiment of the present invention. [Diagram 5] FIG. 5 shows a double-sided tape having one release liner according to one embodiment of the present invention. [Figure 6] FIG. 6 shows a double-sided tape having two release liners according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] <Definition> As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0029] As used herein, the terms "comprising," "comprises," and "comprised of" are synonymous with "including," "includes," "containing," or "contains," and are inclusive or open-ended and do not exclude additional, unrecited members, elements, or method steps.

[0030] As used herein, the term "consisting of" excludes any element, component, material or method step not specified. For completeness, the term "comprising" encompasses "consisting of".

[0031] When amounts, concentrations, dimensions, and other parameters are expressed in the form of ranges, preferred ranges, upper values, lower values, or preferred upper and lower values, it is to be understood that the range obtained by combining any upper value or preferred value with any lower value or preferred value is also specifically disclosed, regardless of whether the resulting range is expressly stated in the context.

[0032] Furthermore, in accordance with standard understanding, weight ranges expressed as "from 0" specifically include 0% by weight: the component defined by said range may or may not be present in the composition.

[0033] The terms "preferred," "preferably," "desirable," and "particularly" are used frequently herein to refer to embodiments of the present disclosure that may afford certain advantages, under particular circumstances. However, the recitation of one or more preferred, preferred, desirable, or particular embodiments does not imply that other embodiments are not useful, and is not intended to exclude such other embodiments from the scope of the present disclosure.

[0034] In this application, the word "may" is used in its permissive (i.e., possible) rather than mandatory sense.

[0035] Room temperature, as used herein, is 23° C.±2° C. As used herein, "ambient conditions" refers to the surrounding temperature and pressure in which the composition is located or in which an adhesive, sealant, coating, or composite structure derived from said composition is located.

[0036] As used herein, the term "water" is intended to include tap water, spring water, purified water, deionized water, demineralized water, and distilled water. Water is included in the compositions of the present invention in liquid form. The presence of solid water particles (ice) is undesirable, since solid water cannot be mobilized to form hydrates necessary for the strength development of the set composition.

[0037] As used herein, "basic" means a base rather than an acid. More specifically, according to the Lewis theory of acids and bases, a base is an electron pair donor. This definition includes, but is not limited to, Bronsted-Lowry bases, which are compounds that act as proton acceptors.

[0038] As used herein, the terms "monomer" and "comonomer" refer to a molecule that can be converted into a polymer, synthetic resin, or elastomer by itself or in combination with other similar molecules or compounds. The terms are not limited to small molecules, but include oligomers, polymers, and other large molecules that can combine with themselves or other similar molecules or compounds.

[0039] As used herein, "macromonomer" refers to a polymer having at least one functional group capable of undergoing a polymerization reaction. Thus, a macromonomer is a polymeric monomer that can be converted into a homopolymer or copolymer of a defined structure. As used herein, macromonomer does not exclude the inclusion of two or more polymer chains attached to one functional group.

[0040] As used herein, the term "(co)polymer" includes homopolymers, copolymers, block copolymers and terpolymers.

[0041] As used herein, "polymerization conditions" are conditions that form at least one monomer into a polymer, such as temperature, pressure, atmosphere, ratio of starting components used in the polymerization mixture, reaction time, or external stimuli of the polymerization mixture. The polymerization process may be carried out in bulk, or in solution, or in other conventional polymerization modes. The process is operated under any of the reaction conditions appropriate to the polymerization mechanism.

[0042] "Free radical polymerization" refers to the polymerization of a monomer composition in the presence of a polymerization initiator that forms radicals under polymerization conditions, either by thermal decomposition, photochemical decomposition, or by oxidation-reduction reactions.

[0043] As used herein, the term "free radical initiator" refers to a chemical species that, upon exposure to sufficient energy (e.g., in the form of light or heat), is uncharged but breaks down into two parts, each of which has at least one unpaired electron. Thus, a thermal free radical initiator is liberated upon exposure to heat. Known thermal free radical initiators include, but are not limited to, peroxide compounds, azo compounds, and persulfate compounds.

[0044] The term "photoinitiator" as used herein refers to a compound that can be activated by exposure to an energetic activation beam (e.g., electromagnetic radiation). Specifically, "free radical photoinitiator" as used herein refers to a photoactive compound that generates free radicals, which can initiate polymerization or reactions by addition to C=C double bonds present in the composition. Such free radical photoinitiators are conventionally classified as Norrish type I photoinitiators and Norrish type II photoinitiators. Norrish type I radical photoinitiators undergo a Norrish type I reaction upon exposure to actinic radiation: this reaction is defined by IUPAC as the alpha cleavage of an excited carbonyl compound to produce an acyl-alkyl radical pair (from acyclic carbonyl compounds) or an acyl-alkyl biradical (from cyclic carbonyl compounds) as the primary photoproduct. Norrisch type II radical photoinitiators undergo a Norrisch type II reaction upon exposure to actinic radiation: this reaction is defined by IUPAC as the photochemical elimination of γ-hydrogen from an excited carbonyl compound to produce a 1,4-biradical as the primary photoproduct.

[0045] The term "aprotic solvent" as used herein refers to a solvent that does not produce or accept protons. Conversely, a "protic solvent" is a solvent that can produce or accept protons. As used herein, a "polar solvent" refers to a solvent that has a dielectric constant (ε) greater than 5 measured at 25° C. The term encompasses both aprotic and protic solvents. Measurement of the dielectric constant (ε) is well known in the art and within the knowledge of the skilled artisan: in such measurements, reference may be made to the use of measuring voltage across a parallel plate capacitor.

[0046] The term softening point (° C.) used herein with respect to tackifiers and waxes is the Ring & Ball softening point, which is measured according to ASTM E28 unless otherwise specified.

[0047] As used herein, the term "hot melt" refers to a composition that is substantially non-flowable at room temperature but converts to a flowable state at elevated application temperatures, e.g., 100-160°C. However, the compositions of the present invention exhibit "cold flow," which as used herein refers to the distortion or viscous flow of the composition at room temperature under applied pressure, particularly finger pressure. The compositions do not exhibit a liquid to solid transition and generally do not return to their original dimensions when pressure is removed.

[0048] As used herein, the term "release liner" refers to a thin flexible sheet that can be brought into intimate contact with a pressure-sensitive adhesive surface and then subsequently peeled off without damaging the adhesive coating. Exemplary materials of which release liners can be or may be made include: polyethylene; polypropylene; polyesters, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); cellulose acetate; polyvinyl chloride; polyvinylidene fluoride; and paper substrates coated or laminated with the aforementioned thermoplastics. For completeness, coated paper or thermoplastic materials are often siliconized or otherwise treated with a release agent to impart improved release properties.

[0049] As is known in the art, release liners are typically left in place for storage and shipping, and are removed only when the bonding operation is to be performed, thereby serving many functions, including preventing contamination of the composition, facilitating its handling, providing support for it, and providing for the transmission of information or identification data.

[0050] As used herein, the term "carrier" refers to a material onto which a curable film of a hot melt pressure sensitive adhesive composition may be coated to stabilize the film. The carrier may add thickness to the article to improve handling. The carrier substrate differs from a release liner in that it cannot be peeled from the curable film without adversely affecting the integrity of the curable film. The carrier may be flexible and may conventionally be selected from polymeric films, metal foils, foams, fabrics, and combinations thereof. For example, the carrier substrate may be selected from the group consisting of polyester, polypropylene, polyethylene, foams, and paper.

[0051] As used herein, the term "transfer coating" refers to a layer or film of pressure-sensitive adhesive that is not supported by a backing.

[0052] Where the viscosity of a composition is referred to herein, this viscosity was measured according to ASTM D 3236-88 using a Thermosel heated chamber and a Brookfield viscometer, spindle 27, 5 rpm, at the stated temperature.

[0053] As used herein, the term "application temperature" refers to the temperature at which the viscosity of the composition is substantially flowable and capable of being deposited as a fluid onto a substrate by contact or non-contact techniques.

[0054] As used herein, the term "equivalents (eq.)," as is usual in chemical notation, relates to the relative numbers of reactive groups present in a reaction.

[0055] As used herein, the term "equivalent weight" refers to the molecular weight divided by the functionality, so "epoxy equivalent weight" (EEW) means the weight in grams of a resin containing one equivalent of epoxy.

[0056] The term "epoxide" as used herein means a compound characterized by the presence of at least one cyclic ether group, i.e., an ether oxygen atom is bonded to two adjacent carbon atoms, thereby forming a cyclic structure. The term is intended to encompass monoepoxide compounds, polyepoxide compounds (having two or more epoxide groups), and epoxide-terminated prepolymers. The term "monoepoxide compound" is meant to indicate an epoxide compound having one epoxy group. The term "polyepoxide compound" is meant to indicate an epoxide compound having at least two epoxy groups. The term "diepoxide compound" is meant to indicate an epoxide compound having two epoxy groups.

[0057] The epoxides may be unsubstituted or inertly substituted. Examples of inert substituents include chlorine, bromine, fluorine and phenyl.

[0058] As used herein, "(meth)acrylic" is an abbreviation that refers to "acrylic" and / or "methacrylic." Thus, the term "(meth)acrylate" collectively refers to acrylates and methacrylates.

[0059] As used herein, "C1-C n An "alkyl" group refers to a monovalent group containing 1 to n carbon atoms, i.e., an alkane group, and includes straight-chain and branched organic groups. Thus, "C1-C 18An "alkyl" group refers to a monovalent group containing 1 to 18 carbon atoms, i.e., an alkane group, including straight chain and branched organic groups. 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), the tolerance of one or more non-halogen substituents in an alkyl group is described in the specification.

[0060] As used herein, "C1-C n The term "hydroxyalkyl" refers to a HO-(alkyl) group having 1 to n carbon atoms, where the point of attachment of the substituent is through the oxygen atom and the alkyl group is as defined above.

[0061] "Alkoxy group" refers to a monovalent group represented by -OA, where A is an alkyl group; non-limiting examples of which are methoxy, ethoxy, and iso-propyloxy. As used herein, "C-C 12 The term "alkoxyalkyl" refers to an alkyl group having an alkoxy substituent, as defined above, where the moiety (alkyl-O-alkyl) contains a total of 1 to 12 carbon atoms; such groups include methoxymethyl (-CHOCH), 2-methoxyethyl (-CHCHOCH), and 2-ethoxyethyl.

[0062] The term "C2-C6 alkylene" as used herein is defined as a saturated divalent hydrocarbon group having from 2 to 6 carbon atoms. In general in this disclosure, such alkylene groups may be unsubstituted or substituted with one or more halogens. Specifically, within the monomers of formula (I) herein, such alkylene groups (X) may be optionally substituted with one or more groups selected from halogens, OH, or COOH.

[0063] "C3-C30 The term "cycloalkyl" is understood to mean a saturated monocyclic or polycyclic hydrocarbon group having 3 to 30 carbon atoms. In the present invention, such cycloalkyl groups may be unsubstituted or substituted with one or more halogens. Where applicable for a given moiety (R), the tolerance of one or more non-halogen substituents in a cycloalkyl group is described herein. Examples of cycloalkyl groups include cyclopropyl; cyclobutyl; cyclopentyl; cyclohexyl; cycloheptyl; cyclooctyl; adamantane; and norbornane.

[0064] As used herein, the term "C3-C 30 "Hydroxycycloalkyl" means a HO-(cycloalkyl) group having 3 to 30 carbon atoms, where the point of attachment of the substituent is through the oxygen atom and the cycloalkyl group is as defined above.

[0065] As used herein, "C3-C 30 "Cycloalkylene" means a divalent radical formed by removing two hydrogen atoms from one or more rings of a cycloalkyl group having three to thirty carbon atoms.

[0066] As used herein, the term "C-C alkyl group" used alone or as part of a larger moiety (such as an "aralkyl group") means a C-C alkyl group. 18An "aryl" group refers to a monocyclic, bicyclic or tricyclic ring system in which the monocyclic ring system is aromatic or at least one of the rings of the bicyclic or tricyclic ring system is aromatic. Bicyclic and tricyclic ring systems include benzo-fused 2-3 membered carbocyclic rings. In the present invention, such aryl groups may be unsubstituted or substituted with one or more halogens. The tolerance of one or more non-halogen substituents in an aryl group, where applicable for a given moiety (R), is described herein. Exemplary aryl groups include: phenyl; (C1-C4) alkylphenyl, such as tolyl and ethylphenyl; indenyl; naphthalenyl, tetrahydronaphthyl, tetrahydroindenyl; tetrahydroanthracenyl; and anthracenyl. It may also be mentioned that the phenyl group is preferred.

[0067] "C6-C 18 "Arylene" means a C6-C 18 It means a divalent group formed by removing two hydrogen atoms from one or more rings of an aryl group, where the hydrogen atoms may be removed from the same or different rings. Representative examples include phenylene and naphthylene.

[0068] As used herein, "C 2- C 20 "Alkenyl" means a hydrocarbyl group having 2 to 20 carbon atoms and at least one unit of ethylenic unsaturation. Alkenyl groups may be straight chained, branched, or cyclic and may be optionally substituted with one or more halogens. Where applicable to a given moiety (R), tolerance for one or more non-halogen substituents within an alkenyl group is described herein. The term "alkenyl" also encompasses groups having "cis" and "trans" configurations, or alternatively, "E" and "Z" configurations, as will be appreciated by those of skill in the art. The above C 2- C 20Examples 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)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-cyclohex-3-enyl.

[0069] As used herein, "alkylaryl" refers to an alkyl-substituted aryl group, both of which are as defined above. Additionally, as used herein, "aralkyl" refers to an alkyl group substituted with an aryl radical, as defined above.

[0070] The term "hetero" as used herein refers to groups or moieties that include one or more heteroatoms, such as N, O, Si, and S. Thus, for example, a "heterocycle" 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, as defined herein, that include N, O, Si, or S, respectively, as part of their structure.

[0071] The composition of the present invention is defined herein as "substantially free" of certain compounds, elements, ions, or other similar components. The term "substantially free" is intended to mean that the compound, element, ion, or other similar component is not intentionally added to the composition and is present only in trace amounts that do not affect (adversely) the desired properties of the coating. Exemplary trace amounts are less than 1000 ppm by weight of the composition.

[0072] The term "substantially free" encompasses embodiments in which a particular compound, element, ion, or other similar component is not present at all in the composition or is present in any amount that is not measurable by techniques commonly used in the art.

[0073] As used herein, the term "anhydrous" is equivalent to the term "substantially free of water". Water is not intentionally added to a given composition and is present only in trace amounts that do not (adversely) affect the desired properties of the composition.

[0074] [Monomers of the copolymer] <a) copolymerizable photoinitiator> The copolymer of the present disclosure comprises, based on the total weight of the monomers, from 0.01 to 10% by weight of a) at least one copolymerizable photoinitiator having an ethylenically unsaturated group and a moiety that decomposes under light irradiation to form radicals. The copolymer preferably comprises, based on the total weight of the monomers, from 0.05 to 5% by weight, preferably from 0.05 to 2.5% by weight of a) the at least one copolymerizable photoinitiator.

[0075] The decomposition of the moiety to form radicals causes crosslinking of the copolymer and thus forms a crosslinked product. The amount of the at least one copolymerizable photoinitiator a) in the copolymer needs to be sufficient to enable sufficient crosslinking performance of the copolymer upon irradiation, but should not be so high as to promote deterioration of the adhesion or ventilation properties of the final crosslinked product.

[0076] In the broadest sense, the at least one copolymerizable photoinitiator has the formula A-(B): b where A represents a substituent having a valence b, including at least one moiety that decomposes to form a radical under irradiation; B represents a moiety that includes an ethylenically unsaturated group; and b is an integer between 1 and 3, preferably 1 or 2. For example, the substituent B may include a (meth)acrylate group or a (meth)acrylamide group, and the moiety A may represent a substituent having a valence b, including at least one moiety that can decompose to form a radical under irradiation, the or each said moiety including a group selected from acetophenone, benzophenone, benzoin, anthraquinone, 9-fluorenone, anthrone, xanthone, thioxanthone, acridone, dibenzosuberone or chromone. In particular, the moiety A may include an acetophenone, benzophenone or benzoin group.

[0077] In an important embodiment of the present invention, a) the at least one copolymerizable photoinitiator has formula (I): [ka] [In the formula, R 0 is C1-C4 alkyl, C6-C 18 Aryl or R 00 and; R 00 has the following structure: [ka] [During the ceremony, R 2 ~R 6 are independently H, OH, SH, halide, CN, C1-C4 alkyl, C1-C4 alkoxy, SR 8 , COOH, COOR 8 , N(R 8 )2, or N(R 8 ) Selected from 3Q; R 7 is H or C1-C4 alkyl; Each R 8are independently C1-C6 alkyl or C6-C 18 aryl; Q is a halide, acetate, phosphate, sulfate or nitrate; However, the group R 2 ~R 6 j is the group: [ka] [where: j is an integer of 1 to 3, preferably 1 or 2; Each R' is independently H, C1-C4 alkyl or C6-C 18 aryl; R″ is H or C1 alkyl; R''' is H or C1 alkyl; Sp is of the following type: [ka] <In the ceremony, k is an integer from 1 to 10; l is an integer from 0 to 25; m is an integer from 1 to 10; n is an integer from 0 to 25; Each X is independently C2-C 12 Alkylene, C3-C 18 Cycloalkylene, or C6-C 18 Selected from arylene; Each Y is independently: [ka] a spacer group represented by the formula: is have] The compound according to the present invention comprises or consists of at least one monomer according to the present invention.

[0078] Within formula (I), the following preferences may be mentioned: These preferences are independent of each other but not mutually exclusive and any combination of said preferences may be made.

[0079] R 0 is preferably C1-C4 alkyl or C6 aryl; R 2 ~R 6 are preferably independently selected from H, OH, C1-C4 alkyl and C1-C4 alkoxy, more preferably independently selected from H and C1-C4 alkyl; R 7 is preferably C alkyl; 8 is preferably independently selected from C1-C6 alkyl, more preferably independently selected from C1-C4 alkyl; each R' is preferably independently selected from H, C1-C4 alkyl, or C6 aryl.

[0080] Although not intended to limit the invention, exemplary copolymerizable photoinitiators that may be useful in the present disclosure include benzophenone (meth)acrylate, benzophenone (meth)acrylamide, acetophenone (meth)acrylate, and compounds having the following structure: [ka] Benzophenone derivatives having the formula:

[0081] Particularly preferred may be mentioned the use of benzophenone methacrylate as copolymerizable photoinitiator.

[0082] <b)エポキシ(メタ)アクリレートモノマー> The copolymer of the present disclosure comprises 0.01-10 wt. % of b) at least one epoxy (meth)acrylate monomer, said monomer having at least one (meth)acrylate group and at least one epoxide group, based on the total weight of monomers. It is preferred that the copolymer comprises 0.05-5 wt. %, preferably 0.5-5 wt. %, more preferably 0.5-2.5 wt. % of b) said at least one epoxy (meth)acrylate compound, based on the total weight of monomers.

[0083] The or each epoxy (meth)acrylate monomer contained in the copolymer is preferably characterized by a combined equivalent weight of the epoxide groups and the (meth)acrylate groups of from 100 to 700 g / eq, especially from 120 to 320 g / eq.

[0084] The epoxy (meth)acrylate monomer can be obtained by reacting acrylic acid or methacrylic acid with a polyepoxide compound in a stoichiometric ratio such that at least one (meth)acrylate group and at least one epoxide group are retained in the resulting adduct. By appropriately changing the amounts of the polyepoxide compound and (meth)acrylic acid to be reacted, an epoxy compound having a desired (meth)acrylation rate can be obtained. For example, the amount of (meth)acrylic acid to be reacted per equivalent of epoxide group is preferably 0.1 to 0.7 equivalents.

[0085] Without intending to limit the present invention, suitable reactant polyepoxide compounds may be liquid, solid, or in solution in a solvent. Based on the above characteristics, it is desirable for such reactant polyepoxide compounds to have an epoxide equivalent weight of 100 to 700 g / eq, for example, 120 to 320 g / eq. And generally, diepoxide compounds having an epoxide equivalent weight of less than 500 g / eq, or even less than 400 g / eq are preferred: this is mainly from the viewpoint of cost, and in the production thereof, low molecular weight epoxy resins require more limited processing in purification.

[0086] As examples of types or groups of polyepoxide compounds which may be reacted with (meth)acrylic acid, mention may be made of the polyglycidyl ethers of polyhydric alcohols and polyhydric phenols; the polyglycidyl esters of polycarboxylic acids; and the epoxidized polyethylenically unsaturated hydrocarbons.

[0087] The use of diepoxide compounds is preferred. For example, suitable diglycidyl ether compounds may be aromatic, aliphatic or cycloaliphatic in nature and thus derived from dihydric phenols and dihydric alcohols. And useful classes of such diglycidyl ethers are: diglycidyl ethers of aliphatic and cycloaliphatic diols, such as 1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,12-dodecanediol, cyclopentanediol and cyclohexanediol; bisphenol A diglycidyl ether; bisphenol F diglycidyl ether; diglycidyl O-phthalate, diglycidyl isophthalate and diglycidyl terephthalate; polyalkylene glycol diglycidyl ethers, in particular polypropylene glycol diglycidyl ether; and polycarbonate diol glycidyl ethers. Other suitable diepoxides that may be mentioned include diglycidyl ethers of doubly unsaturated fatty acids C1-C 18 These include diepoxides of alkyl esters; butadiene diepoxide; polybutadiene diglycidyl ether; vinylcyclohexene diepoxide; and limonene diepoxide.

[0088] Further exemplary polyepoxide compounds 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.

[0089] And, examples of highly preferred reactant polyepoxide compounds include: diglycidyl ethers of cyclohexanediol; 1,2-epoxy-4-(epoxyethyl)cyclohexane; bisphenol A epoxy resins; bisphenol F epoxy resins; bisphenol A / F type epoxy resin blends; polypropylene glycol diglycidyl ethers, such as DER® 732; epoxy novolac resins, such as DEN® 438; brominated epoxy resins, such as DER® 542; castor oil triglycidyl ethers, such as ERISYS® GE-35H; polyglycerin-3-polyglycidyl ethers, such as ERISYS® GE-38; and sorbitol glycidyl ethers, such as ERISYS® GE-60.

[0090] It should be noted that the polyepoxide compounds useful for forming the epoxy acrylate adduct can be monomeric or oligomeric. It is believed that the inclusion of monomeric epoxy (meth)acrylate compounds in the composition of the present invention generally results in a cured product with hard and wear-resistant properties. Conversely, the inclusion of oligomeric multifunctional (meth)acrylates generally results in a somewhat softer, but more flexible, cured product. Of course, the use of both monomeric and oligomeric epoxy (meth)acrylate monomers can balance the desired properties of the cured product.

[0091] As will be appreciated by those skilled in the art, partial (meth)acrylation of the epoxide functional groups of the reactant polyepoxide is typically carried out in the presence of a basic catalyst, which includes triphenylphosphine (PPh3), N,N'-dimethyltoluidine, pyridine, imidazole, triethylamine and tributylamine. However, retention of such catalysts in the partially acrylated final product can be detrimental to the storage stability of the product. To prevent crosslinking reactions (and the associated thickening and gelling of the product) during storage, catalyst residues are desirably removed from the epoxy (meth)arylate monomers before they are used to form the copolymer. Exemplary methods for removing residual catalyst are disclosed in, among others: WO2011 / 078113; JP 5-332031; JP 11-012345; JP 2002-145984A; JP 2004-244543; JP 2013-103950; and JP 2019-052273A.

[0092] In an alternative embodiment, a polymerization inhibitor (e.g., a quinone or quinone methide) may be added to the partially (meth)acrylated reaction product prior to storage, however, such inhibitors are not necessarily preferred since they constitute impurities present during the polymerization reaction to produce the copolymer.

[0093] Regardless of the above, suitable epoxy (meth)arylate compounds having at least one (meth)acrylate group and at least one epoxide group may be obtained from commercial sources. Representative commercially available epoxy (meth)arylate compounds include, but are not limited to, glycidyl methacrylate (GMA) (Sigma Aldrich); Uvacure® 1561 and Uvacure® 1562 (Daicel-Allnex Ltd.); and HCT-1 (Henkel Corporation); Synas S-100 (3,4-epoxycyclohexylmethyl methacrylate) (Synasia).

[0094] <c) Ethylenically unsaturated monomer> The copolymer of the present disclosure contains, based on the total weight of the monomers, 80 to 99.98% by weight of c) at least one ethylenically unsaturated monomer, which monomer has no epoxy group or a moiety decomposable by light irradiation. The copolymer preferably contains, based on the total weight of the monomers, 90 to 99% by weight, for example 95 to 99% by weight, of c) the at least one ethylenically unsaturated monomer. Such a monomer can in principle be any ethylenically unsaturated monomer. However, the present invention is particularly applicable to compositions in which the (meth)acrylate monomer constitutes at least 70% by weight, preferably at least 75% by weight, of the total amount of ethylenically unsaturated monomers present in the copolymer.

[0095] <c) i) Aliphatic and cycloaliphatic (meth)acrylate monomers> The copolymer contains c) i) of formula CI: [Chemical formula] [wherein, G is hydrogen, halogen or a C1 alkyl group; R 1 is as follows: C1-C 30 alkyl; C1-C 18 hydroxyalkyl; C1-C 18 alkoxyalkyl; C2-C 30 heteroalkyl; C3-C 30 cycloalkyl; C2-C8 heterocycloalkyl; C2-C 20 alkenyl; and C2-C 12 alkynyl] and may contain at least one (meth)acrylate monomer represented by.

[0096] For example, R 1 is as follows: C1-C 18 alkyl, C1-C 12 hydroxyalkyl; C2-C 18 heteroalkyl, C3-C 18It may be selected from cycloalkyl; C2-C8 heterocycloalkyl; C2-C8 alkenyl, and C2-C8 alkynyl.

[0097] Desirably, the monomer c)i) is R 1 is C1-C 18 alkyl, C1-C6 hydroxyalkyl and C3-C 18 cycloalkyl, and is characterized in that it is selected therefrom.

[0098] Examples of the (meth)acrylate monomer c)i) according to formula (CI) include, but are not limited to: methyl (meth)acrylate; ethyl (meth)acrylate; butyl (meth)acrylate; hexyl (meth)acrylate; 2-ethylhexyl (meth)acrylate; dodecyl (meth)acrylate; lauryl (meth)acrylate; cyclohexyl (meth)acrylate; isobornyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate (HEMA); 2-hydroxypropyl (meth)acrylate; ethylene glycol monomethyl ether (meth)acrylate; ethylene glycol monoethyl ether (meth)acrylate; ethylene glycol monododecyl ether (meth)acrylate; diethylene glycol monomethyl ether (meth)acrylate; trifluoroethyl (meth)acrylate; and perfluorooctyl (meth)acrylate.

[0099] <c)ii) Aromatic (meth)acrylate monomer> The copolymer is c)ii) of formula CII: [Chemical formula] [wherein, Q is hydrogen, halogen or a C1 alkyl group; R 2 is C6-C 18 aryl, C1-C9 heteroaryl, C7-C 18 alkoxyaryl, C7-C 18 alkaryl and C7-C 18 aralkyl, and is selected therefrom] may include at least one (meth)acrylate monomer represented by

[0100] Exemplary (meth)acrylate monomers c)ii) according to formula (CII) - which may be used alone or in combination - include, but are not limited to: benzyl (meth)acrylate; phenoxyethyl (meth)acrylate; and phenoxypropyl (meth)acrylate.

[0101] <c)iii) (meth)acrylate-functionalized oligomer> The copolymer may include at least one (meth)acrylate-functionalized oligomer selected from the group consisting of c)iii) (meth)acrylate-functionalized polyurethane, (meth)acrylate-functionalized polybutadiene, (meth)acrylic polyol (meth)acrylate, polyester (meth)acrylate oligomer, polyamide (meth)acrylate oligomer, and polyether (meth)acrylate oligomer.

[0102] The oligomer c)iii) may have one or more acrylate groups and / or methacrylate groups attached to the oligomer backbone, and these (meth)acrylate functional groups may be at terminal positions on the oligomer and / or may be distributed along the oligomer backbone. The said or each (meth)acrylate-functionalized oligomer c)iii) reacts as a monomer in the derivation of the copolymer; preferably has two or more (meth)acrylate functional groups per molecule and / or has a weight average molecular weight (Mw) of 300 to 1000 daltons.

[0103] <c)iv) Further ethylenically unsaturated monomers> The present invention does not exclude the inclusion of further ethylenically unsaturated monomers that do not conform to the definitions of ci) to ciii) shown herein. However, the addition of such further monomers is desirably restricted by the condition that the said further monomer c)iv) does not exceed 30% by weight of the total amount of ethylenically unsaturated monomers.

[0104] Without intending to limit the invention, such additional ethylenically unsaturated monomers may include: 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; C1-C6 alkyl esters of α,β-monoethylenically unsaturated tricarboxylic acids having at least one free carboxylic acid group; ethylenically unsaturated sulfonic acids, such as vinyl sulfonic acid, styrene sulfonic acid, and acrylamidomethylpropane sulfonic acid. maleimide monomers such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, and cyclohexylmaleimide; nitrile group-containing vinyl monomers such as (meth)acrylonitrile; amide group-containing vinyl monomers such as (meth)acrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and the VEOVA® series of monomers (Shell vinyl ethers, such as vinyl ethyl ether; vinyl ketones, including alkyl vinyl ketones, cycloalkyl vinyl ketones, aryl vinyl ketones, aryl alkyl vinyl ketones, and aryl cycloalkyl vinyl ketones; aromatic or heterocyclic aliphatic vinyl compounds; poly(meth)acrylates of alkane polyols, such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hexylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate;Poly(meth)acrylates of oxyalkane polyols, such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dibutylene glycol di(meth)acrylate, di(pentamethylene glycol) dimethacrylate; polyethylene glycol di(meth)acrylate; and bisphenol A di(meth)acrylates, such as ethoxylated bisphenol A (meth)acrylate ("EBIPMA");

[0105] Representative examples of other ethylenically unsaturated polymerizable monomers c)iv) include, but are not limited to, ethylene glycol dimethacrylate (EGDMA); anhydrides, monoesters and diesters of fumaric acid, maleic acid and itaconic acid with C1-C4 alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol and tert-butanol. Representative examples of vinyl monomers include, but are not limited to, compounds such as vinyl acetate; vinyl propionate; vinyl ethers such as vinyl ethyl ether; and vinyl ethyl ketone. Representative examples of aromatic or heterocyclic aliphatic vinyl compounds include, but are not limited to, compounds such as styrene, α-methylstyrene, vinyltoluene, tert-butylstyrene, 2-vinylpyrrolidone, 5-ethylidene-2-norbornene, and 1-, 3- and 4-vinylcyclohexene.

[0106] For completeness, the copolymerizable acid monomers mentioned above are typically desirably used in the form of their free acids, although this does not preclude partial or complete neutralization of the constituent acid groups of the monomers with a suitable base, so long as this does not impair their participation in the copolymerization.

[0107] [Formation of copolymers by free radical polymerization] The copolymers of the present disclosure are prepared by free radical polymerization. As recognized by those skilled in the art, free radical polymerization is composed of three steps: initiation, which is generated by the decomposition of the initiator to generate an active free radical, which has an unpaired electron and reacts with the monomer present to generate an initiating radical chain; propagation, which is formed by the initiating radical chain attacking a second monomer molecule and transferring its active center to the attacked molecule, and the process is repeated to grow the polymer chain; and termination, which is the stopping of the growth of the polymer chain and the termination of the polymerization by disabling the active center. The two most common termination mechanisms in radical polymerization are coupling and deprotonation.

[0108] The free radical polymerization may be carried out in bulk, in emulsion, in suspension or in solution. Without intending to limit the invention in particular, the copolymer is preferably prepared by free radical solution polymerization: this means that a solution of the monomers in a solvent that can also dissolve the copolymer is polymerized by free radical polymerization, i.e. in the presence of a polymerization initiator. The concentration of the monomers in the solution may vary, but typically the weight ratio of monomer to solvent is in the range of 1:20 to 2:1, for example 1:2 to 1.5:1.

[0109] The free radical solution polymerization reaction is desirably carried out in the presence of a polar solvent having a boiling point, measured at 1 atmosphere (1.01325 Bar), of at least 20° C., e.g., at least 30° C. or at least 40° C. Examples of such polar solvents, which may be used alone or in combination, include, but are not limited to: water; C1-C8 alkanols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and isobutanol; acetonitrile; N,N-di(C1-C4) alkyl acylamides, such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc); hexamethylphosphoramide; N-methylpyrrolidone; pyridine; esters, such as (C1-C8) alkylacetamide ... Examples of suitable alkyl esters include ethyl acetate, ethoxydiglycol acetate, dimethyl glutarate, dimethyl maleate, dipropyl oxalate, ethyl lactate, benzyl benzoate, butyloctyl benzoate, and ethylhexyl benzoate; ketones, such as acetone, ethyl ketone, methyl ethyl ketone (2-butanone), and methyl isobutyl ketone; ethers, such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), and 1,2-dimethoxyethane; 1,3-dioxolane; dimethyl sulfoxide (DMSO); and dichloromethane (DCM). In an exemplary embodiment, the polymerization reaction is carried out in the presence of a (C1-C8) alkyl acetate, particularly ethyl acetate.

[0110] As mentioned above, the free radical polymerization is induced by at least one radical-generating thermal initiator. As will be appreciated by those skilled in the art, a thermal initiator is a compound that can be activated to generate its radicals by thermal energy, e.g., by heating or irradiation with radiation in the infrared or microwave wavelength range. It is conventionally desirable for the polymerization composition to contain 0.1-1 wt. %, e.g., 0.1-0.5 wt. %, of said at least one radical-generating thermal initiator, based on the total weight of the polymerizable monomers.

[0111] While not intending to limit the invention, an exemplary class of radical-generating thermal initiators suitable for use herein are organic peroxides, e.g., selected from: cyclic peroxides; diacyl peroxides; dialkyl peroxides; hydroperoxides; peroxycarbonates; peroxydicarbonates; peroxyesters; and peroxyketals.

[0112] While certain peroxides (e.g., dialkyl peroxides) have been disclosed as useful initiators, particularly in U.S. Pat. No. 3,419,512 (Lees) and U.S. Pat. No. 3,479,246 (Stapleton), and may indeed be useful herein, hydroperoxides are a preferred class of initiators for the present invention. Additionally, while hydrogen peroxide itself may be used, the most preferred polymerization initiators are organic hydroperoxides. For completeness, included within the definition of hydroperoxide are materials such as organic peroxides or organic peresters that decompose or hydrolyze in situ to form organic hydroperoxides: examples of such peroxides and peresters are cyclohexyl and hydroxycyclohexyl peroxides, and t-butyl perbenzoate, respectively.

[0113] In one embodiment of the invention, the radical-generating thermal initiator has the formula: [ka] [In the formula, R p is an aliphatic or aromatic group containing up to 18 carbon atoms, preferably in the formula: R p is C1-C 12 Alkyl groups, C6-C 18 Aryl group, or C7-C 18 The compound may comprise or consist of at least one hydroperoxide compound represented by the formula (I) wherein R is an aralkyl group.

[0114] Exemplary peroxide initiators that may be used alone or in combination may include the following: cumene hydroperoxide (CHP); para-menthane hydroperoxide; t-butyl hydroperoxide (TBH); t-butyl perbenzoate; t-butyl peroxypivalate; di-t-butyl peroxide; t-butyl peroxyacetate; t-butyl peroxy-2-hexanoate; t-amyl hydroperoxide; 1,2,3,4-tetramethylbutyl hydroperoxide; benzoyl peroxide; dibenzoyl peroxide; 1,3-bis(t-butylperoxyisopropyl)benzene; diacetyl peroxide; butyl 4,4-bis(t-butylperoxy)valerate; p-chlorobenzoyl peroxide; t-butylcumyl peroxide; di-t-butyl peroxide; dicumyl peroxide; 2,5-dimethyl-2,5-di-t-butylperoxyhexane; 2,5-dimethyl-2,5-di-t-butylperoxyhex-3-yne; and 4-methyl-2,2-di-t-butylperoxypentane.

[0115] Although not intended to limit the invention, a further exemplary class of radical-generating thermal initiators suitable for use herein are azo polymerization initiators selected from, for example, azonitriles; azoesters; azoamides; azoamidines; azoimidazolines; and macroazo initiators.

[0116] Representative examples of suitable azo polymerization initiators may include: 2,2'-azobis(2-methylbutyronitrile); 2,2'-azobis(isobutyronitrile); 2,2'-azobis(2,4-dimethylvaleronitrile); 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); 1,1'-azobis(cyclohexane-1-carbonitrile); 4,4'-azobis(4-cyanovaleric acid); dimethyl 2,2'-azobis(2-methylpropionate); 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]; 2,2'-azobis(N-butyl-2-methylpropionamide); 2,2' -Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride; 2,2'-azobis[2-(2-imidazolin-2-yl)propane]; 2,2'-azobis(2-methylpropionamidine)dihydrochloride; 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate; 4,4-azobis(4-cyanovaleric acid) polymer with α,ω-bis(3-aminopropyl)polydimethylsiloxane (VPS-1001, manufactured by Wako Pure Chemical Industries, Ltd.); and 4,4'-azobis(4-cyanopentanoic acid)polyethylene glycol polymer (VPE-0201, manufactured by Wako Pure Chemical Industries, Ltd.).

[0117] Redox initiators are combinations of oxidizing and reducing agents and may also be useful in the present invention. Suitable oxidizing agents may be selected from the group consisting of cyclic peroxides, diacyl peroxides, dialkyl peroxides, hydroperoxides, peroxycarbonates, peroxydicarbonates, peroxyesters and peroxyketals. The corresponding reducing agents may be selected from the group consisting of alkali metal sulfites; alkali metal hydrogen sulfites; alkali metal metabisulfites; formaldehyde sulfoxylates; alkali metal salts of aliphatic sulfinic acids; alkali metal hydrogen sulfides; salts of polyvalent metals, in particular Co(ll) salts and Fe(II) salts such as iron(II) sulfate, ammonium iron(II) sulfate or iron(II) phosphate; dihydroxymaleic acid; benzoin; ascorbic acid; and reducing sugars such as sorbose, glucose, fructose and / or dihydroxyacetone.

[0118] It is contemplated that apart from the initiator, the free radical polymerization may be carried out in the presence of a chain transfer agent which acts to transfer the free radicals, reducing the molecular weight of the resulting polymer and / or controlling the chain growth in the polymerization. If a chain transfer agent is added, it is desirable to constitute 0.01 to 1% by weight, based on the total weight of the polymerizable monomers.

[0119] The process for producing the (co)polymer P is preferably carried out in such a way that the (co)polymer has a number average molecular weight (Mn) of 2000 to 50000 Daltons, for example 3000 to 25000 Daltons. The amount of polymerization initiator and chain transfer agent largely determine the number average molecular weight of the (co)polymer, although the choice of solvent is also important.

[0120] While not intending to limit the invention, conventional polymerization conditions include temperatures ranging from 0 to 175° C., e.g., 25 to 125° C., or 50 to 100° C. The polymerization pressure is generally not critical, and as such, the polymerization may be carried out at subatmospheric, atmospheric, or superatmospheric pressure. Apart from pressure, the polymerization may be carried out under the exclusion of oxygen, if desired: the reaction vessel may be equipped with an inert, dry gaseous blanket of, for example, nitrogen, helium, and argon.

[0121] For completeness, it is understood that the polymerization may be carried out as a batch or semi-batch procedure, or as a continuous procedure. As will be appreciated by those skilled in the art, in a batch procedure, the monomers to be polymerized and optionally the solvent used in the polymerization procedure are charged to the reaction vessel, while the majority or total amount of the polymerization initiator is added to the reaction vessel during the course of the polymerization. In a semi-batch process, the polymerization initiator and at least a portion (including the maximum and total amount) of the solvent are initially charged to the reaction vessel. A small portion of the monomers are also charged, but the majority of the monomers to be polymerized are added to the reaction vessel during the course of the polymerization. In a continuous process, the monomers, polymerization initiator, and optionally the solvent are continuously added to the reaction vessel, and the resulting polymer is continuously discharged from the polymerization vessel.

[0122] The polymerizations of the present invention are preferably carried out in a semi-batch procedure, and it is particularly preferred that at least 75% by weight of the total weight of the monomers to be polymerized is added to the reaction vessel during the course of the polymerization reaction.

[0123] There is no particular intention to limit the timing of the introduction of the different functional monomers (a)-c)) of the copolymer into the polymerization procedure. The monomers may be fed to the polymerization vessel in a constant molar ratio either at the beginning of the polymerization (in the case of batch processes) or throughout the polymerization process (in the case of semi-batch and continuous processes). Alternatively, the molar ratio of the monomer types may be varied during the course of the polymerization: this is intended to encompass embodiments in which only monomer a) is added to the polymerization vessel or, conversely, only monomer b) or monomer c) is added to the polymerization vessel during the course of the polymerization. Those skilled in the art may determine the appropriate molar ratio based on the desired morphology or randomness of the copolymer and the reactivity ratios of the monomers.

[0124] The copolymer reaction product may be isolated and purified using methods known in the art, suitable techniques include extraction, evaporation, crystallization, distillation, and chromatography. When free radical solution polymerization is carried out, the copolymer is most conveniently isolated by distilling off the solvent and unreacted starting materials under reduced pressure. If it is intended to store the (optionally purified) copolymer upon preparation, it is desirable to place the polymer in an airtight and moisture-free sealed container. The storage container should not permit the transmission of light radiation.

[0125] [Hot melt composition] As mentioned above, the present disclosure also provides for the use of the copolymer in a reactive hot melt composition, including a reactive hot melt adhesive composition. More specifically, a reactive hot melt composition is provided that includes, based on the weight of the composition, 40-99.99 wt.% of i) at least one copolymer as defined hereinabove and in the appended claims; 0.01-1 wt.% of ii) at least one ionic photoacid generator (PAG); 0-60 wt.% of iii) at least one tackifying resin; and 0-20 wt.% of iv) a wax.

[0126] Components ii)-iv) are described in further detail herein below.

[0127] <ii) Ionic photoacid generator> The hot melt composition of the present invention contains 0.01 to 10% by weight, for example 0.01 to 5% by weight, based on the weight of the composition, of ii) at least one ionic photoacid generator (PAG). When irradiated with light energy, the ionic photoacid generator undergoes a fragmentation reaction, releasing molecules of one or more Lewis acids or Bronsted acids, and catalyzing the ring opening and addition of pendant epoxide groups to form crosslinks. Useful photoacid generators are thermally stable, do not undergo a thermal induction reaction with the formed copolymer, and are easily soluble or dispersible in the curable composition.

[0128] Exemplary cations that can be used as the cationic moiety of the ionic PAG of the present invention include organic onium cations as described in U.S. Patent No. 4,250,311, U.S. Patent No. 3,113,708, U.S. Patent No. 4,069,055, U.S. Patent No. 4,216,288, U.S. Patent No. 5,084,586, U.S. Patent No. 5,124,417, U.S. Patent No. 5,554,664, and U.S. Patent No. 8,030,401. These documents specifically encompass onium salts centered on aliphatic or aromatic Group IVA and VIIA (CAS version), and it is mentioned that onium salts centered on I-, S-, P-, Se-N-, and C-, such as those selected from sulfoxonium, iodonium, sulfonium, selenonium, pyridinium, carbonium, and phosphonium, are preferred. Specific examples thereof include diaryliodonium; triarylsulfonium; triarylsulfoxonium; dialkylphenacylsulfonium; alkylhydroxyphenylsulfonium; and alkylphenyliodonium.

[0129] As is known in the art, the nature of the counter anion in an ionic photoacid generator (PAG) can affect the rate and extent of the cationic addition polymerization of the epoxide groups of copolymer i). By way of example, the order of reactivity among commonly used nucleophilic anions is SbF6 > AsF6 > PF6 > BF4. The effect of the anion on reactivity is due to three main factors that those skilled in the art should make up for in the present invention: (1) the acidity of the protonic acid or Lewis acid generated, (2) the degree of ion pair separation in the propagating cationic chain, and (3) the susceptibility of the anion to fluoride abstraction and the resulting chain termination.

[0130] Exemplary ionic photoacid generators useful in the present composition include: Irgacure® 250, Irgacure® PAG 290 and GSID26-1 (manufactured by BASF SE); Cyracure® UVI-6990 and Cyracure® UVI-6974 (manufactured by Union Carbide); Omnicat 320 (manufactured by IGM Resins USA Inc); Degacure® Kl 85 (manufactured by Degussa); Optomer® SP-55, Optomer® SP-150 and Optomer® SP-170 (manufactured by Adeka); GE UVE 1014 (manufactured by General Electric); and SarCat® CD 1012, SarCat® KI-85, SarCat® CD 1010 and CD SarCat® 1011 (manufactured by Sartomer).

[0131] <iii) Tackifying resin> The hot melt composition of the present invention comprises, based on the weight of the composition, 0 to 60% by weight of iii) at least one tackifying resin. Conventionally, it is desirable for the composition to comprise, based on the weight of the composition, 1 to 60% by weight, such as 15 to 55% by weight, or 25 to 55% by weight of iii) said at least one tackifying resin. Each of the tackifying resins included in the composition preferably has the following characteristics: a softening point of 70 to 150°C; and a viscosity of less than 2000 Pa·s at 150°C.

[0132] Exemplary tackifying resins that may be used alone or in combination in the present invention include: aliphatic and cycloaliphatic petroleum hydrocarbon resins; aromatic petroleum hydrocarbon resins and their hydrogenated derivatives; aliphatic / aromatic petroleum derived hydrocarbon resins and their hydrogenated derivatives; polycyclopentadiene resins, hydrogenated polycyclopentadiene resins, and aromatic modified hydrogenated polycyclopentadiene resins; terpenes, aromatic terpenes, and hydrogenated terpenes; polyterpenes, aromatic modified polyterpenes, and terpene phenols; copolymers of α-methylstyrene with additional vinyl aromatic monomers; α-methylstyrene phenols; and gum rosin, gum rosin esters, wood rosin, wood rosin esters, tall oil rosin, tall oil rosin esters, and hydrogenated rosin esters.

[0133] With regard to the inclusion of a copolymer of α-methylstyrene and a further vinyl aromatic monomer, the copolymer is preferably characterized by a weight average molecular weight (Mw) of at least 40,000 Daltons, and the vinyl aromatic monomer of the copolymer can include styrene, 4-tert-butylstyrene, o-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, vinylnaphthalene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, and combinations thereof.

[0134] Exemplary commercially available tackifying resins having utility in the present invention include rosin esters under the tradenames Foral 85 (glyceryl esters) and Formal 105 (pentaerythritol esters) (Eastman Chemical Co.); Piccolyte S-10, S-25, S-70, S-85, S-100, S-115, S-125, and S-135 polyterpene resins (Pinova Corporation); Arkon® P-70, P-90, P-100, P-125, P-115, M-90, M-100, M-110, and M-120 hydrogenated C5 and / or C9 hydrocarbon feedstocks (Arakawa Chemical Co.); Eastotac® H-100, H-115, H-130, and H-142R (Eastman Chemical Co., Ltd.) Exxon Chemical Co.; Escorez® 5300, 5320, 5380, 5400, 5600 and 5637 (Exxon Chemical); WING TACK® 95 and WING TACK® Extra (Sartomer); Regalite R9001 and Regalite S5100 (Eastman Chemical Co.), Sylvares® 520, 525, 540, SA85, SA100, SA115, SA120, and SA140 (Kraton Corporation).

[0135] <iv)ワックス> Waxes constitute an optional component of the composition of the present disclosure. The hot melt composition may comprise 0-20 wt. % iv) wax, based on the weight of the composition. If added, the composition desirably comprises 0.1-20 wt. %, for example 0.1-10 wt. % iv) wax, based on the weight of the composition. The waxes are added to the hot melt composition to reduce its melt viscosity. These waxes, which are solid at room temperature, may determine the set-up time and softening point of the adhesive.

[0136] Without intending to limit the invention, waxes having utility in the present invention desirably have a softening point of 50 to 150° C. and may include one or more of polyethylene having a number average molecular weight (Mn) of 500 to 7500; petroleum waxes, such as paraffin wax and microcrystalline wax; synthetic waxes made by polymerizing carbon monoxide and hydrogen, such as Fischer-Tropsch wax; polyolefin waxes; and hydrogenated animal, fish or vegetable oils.

[0137] To impart heat resistance, the wax of the composition preferably comprises or consists of at least one functionalized polyolefin, the or each functionalized polyolefin contained in the composition is preferably characterized by a weight average molecular weight of from 2,000 to 20,000 Daltons, for example from 2,500 to 15,000 Daltons.

[0138] Representative olefin monomers from which functional polyolefins may be derived and used alone or in combination include, but are not limited to, ethylene, propylene, butylene, pentene, hexylene, heptene, and octene. It may be noted that ethylene and / or propylene are preferred.

[0139] Representative functionalized monomers include aliphatic and alicyclic (meth)acrylate monomers; aromatic (meth)acrylate monomers; (meth)acrylate functionalized oligomers; α,β-ethylenically unsaturated dicarboxylic acids containing 4 to 6 carbon atoms, and the anhydrides, monoesters, and diesters of these acids; α,β-ethylenically unsaturated monocarboxylic acids containing 3 to 5 carbon atoms, such as acrylic acid, methacrylic acid, crotonic acid, and the like; C1-C2 of crotonic acid; 18Silicone (meth)acrylate monomers, such as those taught and claimed by U.S. Pat. No. 5,605,999 (Chu); poly(meth)acrylates of alkane polyols; poly(meth)acrylates of oxyalkane polyols; vinyl esters, such as vinyl acetate, vinyl propionate, and the VEOVA® series of monomers (Shell Chemical Company); vinyl and vinylidene halides; vinyl ethers, such as vinyl ethyl ether; and vinyl ketones, including alkyl vinyl ketones, cycloalkyl vinyl ketones, aryl vinyl ketones, aryl alkyl vinyl ketones, and aryl cycloalkyl vinyl ketones.

[0140] Among the above-mentioned monomers, it may be mentioned that α,β-ethylenically unsaturated dicarboxylic acids containing 4 to 6 carbon atoms and their anhydrides, C1-C4 alkyl monoesters and C1-C4 alkyl diesters are particularly preferred. The use of fumaric anhydride, maleic anhydride and itaconic anhydride is preferred, among which the use of maleic anhydride is most preferred. And, good results have been obtained when the composition comprises at least one of maleated polyethylene; maleated polypropylene; or maleated poly(ethylene-co-propylene).

[0141] For completeness, exemplary commercially available maleated polyethylene and maleated polypropylene polymers that may be useful herein include: EPOLENE E-43, G-3015, and G-3003 (manufactured by Eastman Chemical); AC 575, AC 573 (manufactured by Honeywell); Fusabond E and Fusabond P (manufactured by DuPont).

[0142] <Additives and auxiliary ingredients> The hot melt compositions obtained according to the present invention typically further comprise adjuvants and additives that can impart improved properties to these compositions. For example, the adjuvants and additives can determine the elastic properties, including elastic recovery; processing time; cure time; and residual tack. Such adjuvants and additives include: plasticizers; stabilizers, including UV stabilizers; fillers; drying agents; adhesion promoters; air release agents; defoamers; flame retardants; rheological aids; and color pigments, such as titanium dioxide, iron oxide, or carbon black. For completeness, it is noted that the compositions are desirably substantially free of solvents and non-reactive diluents.

[0143] Such auxiliaries and additives may be used in any combination and proportion desired, provided they do not adversely affect the properties and essential characteristics of the composition. With occasional exceptions, these auxiliaries and additives should not collectively comprise more than 50% by weight of the entire composition, and preferably should not comprise more than 20% by weight of the composition.

[0144] For the purposes of the present invention, a "plasticizer" is a substance that reduces the viscosity of the composition, thus facilitating its processability. As used herein, the plasticizer may constitute up to 5% by weight based on the total weight of the composition, and is preferably selected from the group consisting of: polydimethylsiloxane (PDMS); diurethane; monofunctional, linear or branched C4-C 16The plasticizers are selected from the group consisting of ethers of alcohols, such as Cetiol OE (from Cognis Deutschland GmbH, Duesseldorf); esters of abietic acid, butyric acid, thiobutyric acid, acetic acid, propionic acid and citric acid; esters based on nitrocellulose and polyvinyl acetate; fatty acid esters; dicarboxylic acid esters; esters of OH-containing or epoxidized fatty acids; glycolic acid esters; benzoic acid esters; phosphoric acid esters; sulfonic acid esters; trimellitic acid esters; polyether plasticizers, such as end-capped polyethylene or polypropylene glycol; polystyrene; hydrocarbon plasticizers; chlorinated paraffins; and mixtures thereof. It should be noted that, in principle, phthalic acid esters can be used as plasticizers, but these are not preferred due to their toxicological potential. The plasticizer preferably comprises or consists of one or more polydimethylsiloxanes (PDMS).

[0145] "Stabilizer" for the purposes of the present invention is understood to mean antioxidant, UV stabilizer or hydrolysis stabilizer. In this specification, the stabilizer may constitute up to 10% by weight or up to 5% by weight in total, based on the total weight of the composition. Typical commercial examples of stabilizers suitable for use herein include sterically hindered phenols, of which Irganox 1726 is a commercial example available from BASF; thioethers; benzotriazoles; benzophenones; benzoates; cyanoacrylates; acrylates; amines of the hindered amine light stabilizer (HALS) type; phosphorus; sulfur; and mixtures thereof.

[0146] As mentioned above, the composition according to the invention can additionally contain fillers. Suitable here are, for example, chalk, lime powder, precipitated and / or calcined silicic acid, zeolites, bentonite, magnesium carbonate, diatomaceous earth, alumina, clay, talc, titanium oxide, iron oxide, zinc oxide, sand, quartz, flint, mica, glass powder and other ground mineral substances. Organic fillers can also be used, in particular carbon black, graphite, wood fibers, wood flour, sawdust, cellulose, cotton, pulp, cotton, wood chips, chopped straw, rice husks, ground walnut shells and other chopped fibers. Short fibers such as glass fibers, glass filaments, polyacrylonitrile, carbon fibers, Kevlar fibers, polyethylene fibers, etc. Aluminum powder is also suitable as a filler.

[0147] As further fillers, hollow spheres with mineral or plastic shells may also be mentioned. These may be, for example, hollow glass spheres, which are commercially available under the trade name Glass Bubbles®. Plastic-based hollow spheres, such as Expancel® or Dualite®, may also be used, which are described in EP 0 520 426 B1. These are made of inorganic or organic materials, and have a diameter of 1 mm or less, preferably 500 μm or less, respectively.

[0148] Fillers that impart thixotropic properties to the composition may be preferred for many applications: such fillers are also described as rheological aids, e.g. hydrogenated castor oil, fatty acid amides, or swellable plastics such as PVC.

[0149] The total amount of filler present in the composition of the present invention is preferably 0 to 30 wt%, more preferably 0 to 20 wt%, based on the total weight of the composition. The desired viscosity of the curable composition at application temperature is typically determined by the total amount of filler added.

[0150] It should be noted that compounds having metal chelating properties may be used in the compositions of the present invention to help enhance adhesion of the curable adhesive to the substrate surface. Also suitable for use as an adhesion promoter is an acetoacetate functionalized modified resin sold by King Industries under the trade name K-FLEX XM-B301.

[0151] Further exemplary adhesion promoters include those of formula (BII): [ka] wherein each R is independently selected from methyl or ethyl; and n is 1 to 10. Mention may be made of glycidoxyalkylalkoxysilanes having the formula:

[0152] Exemplary silanes include, but are not limited to, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxymethyltrimethoxysilane, γ-glycidoxymethyltriethoxysilane, γ-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltriethoxysilane; and 8-glycidoxyoctyltrimethoxysilane. When present, it is desirable for the epoxide-functional silanes to constitute less than 20% by weight, preferably less than 10% by weight or less than 5% by weight, based on the total weight of the copolymer i).

[0153] [Method and Use] The reactive hot melt adhesive composition may be formulated by combining predetermined amounts of the components. In those embodiments in which the components are mixed, this may be carried out using any of the mixing techniques known in the art: however, it will certainly be preferred that the components are not mixed by hand, but instead by machine, such as a static or dynamic mixer, under anhydrous conditions, and without deliberate exposure to light, in predetermined amounts.

[0154] A first representative example of a mixing procedure involves placing all ingredients except the hybrid base polymer in a jacketed mixing kettle equipped with a rotor, and then raising the temperature of the mixture to above the softening point of the base polymer being added: temperatures between 100°C and 160°C are sufficient, although it will be understood that the exact temperature will depend on the softening and melting points of the particular ingredients. The polymer is then introduced into the kettle under stirring, and stirring is continued until a consistent homogenous mixture is formed. The contents of the kettle may be protected with an inert gas, such as carbon dioxide or nitrogen, throughout the mixing process.

[0155] In a second representative example of a mixing procedure, a resin or oil that is compatible with the chemistry of the base copolymer is first charged to the mixing kettle. The resin or oil is then melted or adjusted to obtain a liquid to which the base copolymer is added in stages and dissolved in the liquid. After the base polymer is added, the remaining ingredients are added to the mixing kettle.

[0156] In a further typical example, all components of the composition may be combined or homogenously mixed together in solid form. The solid feed may then be placed in a melting tank and brought to the temperature required for dispensing in molten form. Again, the exact temperature of the melting tank will depend on the softening and melting points of the particular components.

[0157] In general, the hot melt composition may be applied to a substrate by conventional methods such as brushing; roll coating; doctor blade application; printing; jetting; omega coating; controlled seam coating; dot coating; and spraying methods including, but not limited to, air atomized spray, air assisted spray, airless spray, high volume low pressure spray, slot spray, and curtain spray coating. In those embodiments in which the hot melt composition is used in a potting operation, the composition is typically introduced into a defined mold by static potting or centrifugal potting. In static potting, the composition is introduced into the potting mold while the mold is substantially stationary. In centrifugal potting, the potting composition is introduced into the potting mold while the mold is rotating such that the rotation of the mold forces the potting composition toward the end of the rotating mold by centrifugal force. In both static and centrifugal potting, the introduction of the hot melt composition may be contact or non-contact.

[0158] For coating, adhesive and sealant applications, it is recommended that the composition be applied to a wet film thickness of 10 to 500 μm. In another statement, which is not intended to be mutually exclusive with the above, it is recommended that the composition be applied to achieve a coat weight of 50 to 250 gsm per square meter (gsm), preferably 50 to 150 gsm.

[0159] Central to any of the aforementioned application methods is that the hot melt composition is sufficiently fluid when applied in order to cover the substrate to which it is applied. In certain circumstances where the substrate is porous, the hot melt composition becomes sufficiently fluid to penetrate the substrate. Thus, the hot melt composition is preferably characterized by a melt viscosity of up to 100000 mPa·s measured at 120°C.

[0160] That being said, useful application temperatures typically range from 100° C. to 160° C. or 110° C. to 150° C., with lower temperatures within this range being preferred as they may extend the useful life of the curable composition. The temperature of the composition can be raised above its mixing temperature to the application temperature using conventional means, including microwave induction.

[0161] Immediately after application, the applied composition is cured under light irradiation. The energy source used to promote the curing of the applied composition emits at least one of ultraviolet (UV) radiation, infrared (IR) radiation, visible light, X-rays, gamma rays, or electron beam (e-beam). After application, when irradiated using a commercially available curing device, the composition may be activated typically in less than 2 minutes, generally in 0.1 to 100 seconds (e.g., 3 to 12 seconds). For completeness, the activation of the composition may be effectively performed in an in-line process in which the coated substrate is conveyed under the curing device while emitting radiation: it will be understood that the activation time mentioned above is the exposure time of the applied composition to irradiation in such an in-line process.

[0162] The irradiated ultraviolet light usually has a wavelength of 150 to 600 nm, preferably 200 to 450 nm. Useful ultraviolet 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 light sources such as excimer lasers and argon ion lasers.

[0163] When using an electron beam to cure the applied composition, typical parameters of the operating device are: accelerating voltage of 0.1-100 keV; -3 a vacuum of 0.0001 Pa; an electron current of 0.0001 to 1 ampere; and a power of 0.1 watts to 1 kilowatts.

[0164] The amount of radiation required to sufficiently cure a particular composition (e.g., so that the coating is set) depends on a variety of factors, including the angle of incidence of the radiation and the thickness of the composition applied. However, generally, it is in the range of 5 to 5000 mJ / cm 2 Typical curing doses are: 50-500 mJ / cm 2 , for example 50-200mJ / cm 2 A curing dose of 100 mg / kg / day can be considered highly effective.

[0165] The reactive hot melt compositions according to the invention may find utility in particular in: casting resins; potting and sealing resins; binders for fibers and / or particles; coating of glass; coating of mineral building materials, such as lime and / or cement-bonded plasters, gypsum-containing surfaces, fiber cement building materials and concrete; coating and sealing of wood and wood-based materials, such as chipboard, fiberboard and paper; coating of metal surfaces; and coating and sealing of various plastic surfaces.

[0166] It is clear that the hot melt composition can be used to bond a first and a second substrate: in the broadest sense, the composition is applied between the two substrates and cured under irradiation. Such a bonding operation can be carried out using two main techniques: direct application of the hot melt composition and application via transfer, which is described in more detail below. In a first embodiment, the hot melt composition is applied to at least one surface (S 1 ) and at least one surface (S 2 ) and the first and second substrates (S 1 , S 2 ) are contacted with the intervening composition. In an alternative embodiment, the hot melt composition is applied only to the surface of the first substrate, which is then contacted with the second substrate.

[0167] First base material (S 1 ) and the second substrate (S 2) may be the same or different, but are not particularly limited in either case. Substrates that may be joined include, for example, the following: ferrous metal materials, such as iron, stainless steel, cold-rolled steel, and electrogalvanized steel; non-ferrous metal materials, such as aluminum, zinc, and alloys thereof; silicon materials, such as glass, monocrystalline silicon, polycrystalline silicon, amorphous silicon, or silicon oxide; engineering plastics; thermoplastics, such as polyolefins, including polyethylene (PE) and polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), and acrylonitrile butadiene styrene (ABS); and carbon materials, such as carbon fibers.

[0168] For completeness, the shapes of the first and second substrates are also not particularly limited, so long as the substrates have shapes that allow them to be bonded together. Desirably, the first substrate to be bonded has a surface that has a shape that is complementary to the surface of the second substrate, allowing the first and second substrates to interlock with the composition disposed therebetween.

[0169] As described above, the first and second substrates (S 1 , S 2 ) may be joined together by a transfer process. Such a process includes the steps of: (i) providing an article (A) comprising a curable film of the hot melt composition defined above, the film being disposed on a release liner and / or a carrier substrate; (ii) transferring the curable film of the article to a substrate (S); 1 , S 2 (iii) attaching the polymerizable polymer to at least one of the substrates (S 1 , S 2 (iv) interfitting the substrates; and (iv) curing the film between the substrates to be adhered together, wherein the release liner of article (A), if present, is removed before and / or after step (ii).

[0170] An article (A) comprising a curable film of the hot melt composition defined above disposed on a release liner and / or carrier substrate represents a further aspect of the present disclosure. Article (A) may be a label, a single-sided tape, a transfer tape, or a double-sided tape.

[0171] Without intending to limit the disclosure, for the sake of completeness, an exemplary article (A) is described with reference to the accompanying drawings, in which:

[0172] In Figure 1, there is shown a single-sided tape (101) comprised of a carrier (102) and a curable film (103). The embodiment depicted in Figure 2 can be either a single-sided tape or label (201), which consists of a carrier (102) and a curable film (103): the curable film (103) is covered with a release liner (104) to protect the curable film and prevent unwanted adhesion of the curable film (103).

[0173] 3 and 4 show the removal of the curable film from the release liner to the target surface (S 1 , S 2 3 shows a transfer tape that is particularly useful for transferring a curable film (103) onto a hot melt composition. In FIG. 3, the transfer tape (301) is comprised of a release liner (104) coated with a curable film (103) of a hot melt composition. The release liner (104) desirably has release properties on both sides, but those sides should not have equal release properties. As a result, when the transfer tape (301) is wound and unwound from a roll, there will be differences in the release effectiveness of the two sides of the release liner (104).

[0174] In Figure 4, the transfer tape (401) is comprised of a curable film (103) sandwiched between a first release liner (104) and a second release liner (105). The first release liner (104) and the second release liner (105) may have different release properties relative to the curable film, allowing the liners (104, 105) to be peeled away independently of one another.

[0175] The double-sided adhesive tape (501) is depicted in FIG. 5 and is composed of a carrier (102) having a first curable film (103) on a first side of the carrier (102) and a second curable film (106) on a second side of the carrier (102). The first curable film (103) and the second curable film (106) may be the same or different and may be derived from the same or different hot melt compositions, with the proviso that at least one of the hot melt compositions is provided in accordance with the present disclosure. A release liner (104) covers and protects the second curable film (106), and this liner (104) desirably has release properties on both sides, but should not have equal release properties on those sides. In such a situation, i.e. when winding and unwinding the transfer tape (501) from the roll, there will be differences in the release effectiveness on both sides of the release liner (104).

[0176] A second embodiment of a double-sided adhesive tape (601) is provided in FIG. 6. The depicted tape (601) is composed of a carrier (102) having a first curable film (103) on a first side of the carrier (102) and a second curable film (106) on a second side of the carrier (102). The first curable film (103) and the second curable film (106) may be the same or different, i.e., they may be obtained from the same or different hot melt compositions, with the proviso that at least one of said hot melt compositions is provided in accordance with the present disclosure. A first release liner (104) covers and protects the first curable film (103). A second release liner (105) covers and protects the second curable film (106). The first release liner (104) and the second release liner (105) may have different release properties with respect to the curable films (103, 106).

[0177] In forming the aforementioned article (A), the hot melt composition is applied to a release liner and / or carrier and then cooled. Cooling can be accomplished, for example, by applying the hot melt composition to a substrate conveyed by a coating roll having cold water circulating therethrough. Alternatively, the hot melt composition and the substrate (or a thermoplastic precursor of the substrate) can be coextruded as a laminate, and the laminate can be cooled and optionally stretched to induce partial orientation and crystallization.

[0178] The parameters of the manufacturing process (including, inter alia, the particular composition used, its application thickness, and the operating conditions of the manufacturing equipment) can, of course, affect the degree of orientation and, consequently, the anisotropy, tack, and peel force properties of the pressure-sensitive adhesive. For example, if the cooling rate is slow, the cooled pressure-sensitive adhesive can have high tack and an isotropic peel force. If the cooling rate is faster, the pressure-sensitive adhesive can have low tack and a more anisotropic peel force. If the cooling rate is fast, the cooled pressure-sensitive adhesive can have fairly low pressure tack and low or no detectable peel force.

[0179] The following examples are illustrative of the present invention and are not intended to limit the scope of the invention. EXAMPLES

[0180] The following compounds were used in the examples: 4-(Methacryloyloxy)benzophenone: radical curing photoinitiator, Molbase. Bis[4-diphenylsulfonium phenyl]sulfide-bishexafluoroantimonate: photoacid generator, Toronto Research Chemical. Thiophenoxyphenylsulfonium hexafluoroantimonate: photoacid generator, Toronto Research Chemicals. 3,4-epoxycyclohexylmethyl methacrylate: monomer, epoxy equivalent 200g / eq, Synasia. 2-Ethylhexyl acrylate: monomer, Sigma Aldrich. Methyl acrylate: monomer, Sigma Aldrich. Butyl acrylate: monomer, Sigma Aldrich. Acrylic acid: monomer, Sigma Aldrich.

[0181] The following abbreviations were used in the examples: RT: room temperature; AF: adhesion failure; CF: cohesion failure; TF: transfer failure; HDPE: high density polyethylene; PP: polypropylene; PVC: polyvinyl chloride; PS: polystyrene; PMMA: polymethyl methacrylate; ABS: acrylonitrile butadiene styrene; PA: polyamide.

[0182] The following analytical tests were performed on the hot melt compositions described later in this specification. For completeness, peel strength tests, static shear tests, and shear adhesion failure tests (SAFT) were performed at: a number of different coating weights (grams per square meter, gsm); and a number of different UV doses for curing the reactive hot melt compositions.

[0183] Viscosity: The viscosities reported herein were measured according to ASTM D 3236-88 at 120°C, 130°C and 140°C using a Thermosel heated chamber containing an 11 g sample of material and a Brookfield Viscometer Spindle 27 at 1-5 rpm.

[0184] Peel strength: This parameter was measured according to International Organization for Standardization (ISO) standard 29862 as follows. Each adhesive member was cut into a 25 mm x 150 mm film, which was laminated onto a standardized substrate by rolling a 2 kg roller back and forth for three strokes at a speed of 10 mm / s. The laminate was left at room temperature for a specified time. The adhesive film was peeled from the substrate surface in a 180° direction at a specified speed of 300 mm / min. The force required for this peeling (peel force) was measured and recorded as adhesive strength (N / inch).

[0185] Shear Adhesion Failure Test (SAFT): The hot-fail temperature of the hot melt compositions under shear was tested according to ASTM D4498 using an Elastocon ES 07-II instrument. Each adhesive part was cut into a 25 mm x 25 mm film and laminated onto a standardized substrate by two passes of a 2 kg roller at a speed of 10 mm / s. A weight (1 kg) was attached to each part and the temperature was increased from room temperature at a controlled rate (0.5°C / min) until 200°C was reached or the adhesive part broke.

[0186] <Part 1: Preparation of copolymers and hot melt compositions> Three copolymers were individually prepared by free radical solution polymerization in ethyl acetate according to the monomer compositions shown in Table 1. The weight percentages shown in Table 1 correspond to the weight of each particular monomer based on the total weight of monomers.

[0187] [Table 1]

[0188] Upon completion of the polymerization of Copolymer 1 and Copolymer 2, a cationic photoinitiator was added to the reaction vessel. The solvent was removed by distillation to yield a hot melt composition as defined in Table 2 below.

[0189] [Table 2]

[0190] <Part 2: Viscosity characteristics> The exemplified hot melt compositions are solid at room temperature but have temperature dependent viscosity characteristics as defined in Table 3 below.

[0191] [Table 3]

[0192] <Part 3: Performance of hot melt compositions at 65 gsm coating weight> The peel strength of the examples and comparative examples was tested against steel substrates after application at a coating weight of 65 gsm and curing at a UV dose of 65 mJ, and the results of these tests are shown in Table 4 below.

[0193] [Table 4]

[0194] Part 4: Performance of hot melt compositions at higher coating weights The peel strength of the examples and comparative examples was tested on each steel substrate after application at a coating weight of 80 or 100 gsm and curing at a UV dose of 80 or 100 mJ. The results of these tests are shown below in Table 5.

[0195] [Table 5]

[0196] <Part 5: Performance of hot melt compositions at 80gsm coating weight on different substrates> The peel strength of the Examples and Comparative Examples was tested against a number of different substrates after application at a coating weight of 80 gsm and curing at a UV dose of 80 mJ, and the test results are shown in Table 6 below.

[0197] [Table 6]

[0198] In view of the above description and examples, it will be apparent to one skilled in the art that equivalent modifications can be made without departing from the scope of the claims.

Claims

1. 1. A copolymer obtained by free radical polymerization, said polymer comprising, based on the total weight of monomers: a) 0.01 to 10% by weight of at least one copolymerizable photoinitiator having an ethylenically unsaturated group and a moiety that decomposes under light irradiation to form radicals; b) 0.01 to 10 wt. % of at least one epoxy (meth)acrylate monomer having at least one (meth)acrylate group and at least one epoxide group; and c) 80 to 99.98% by weight of at least one ethylenically unsaturated monomer that does not have an epoxide group or a moiety that decomposes under light irradiation to form radicals A copolymer comprising:

2. Based on the total weight of the monomers, a) 0.05 to 5% by weight, preferably 0.05 to 2.5% by weight, of at least one copolymerizable photoinitiator having an ethylenically unsaturated group and a site that decomposes under light irradiation to form a radical; b) 0.05 to 5 wt. %, preferably 0.5 to 5 wt. %, of at least one epoxy (meth)acrylate monomer having at least one (meth)acrylate group and at least one epoxide group; and c) 90 to 99% by weight of at least one ethylenically unsaturated monomer that does not have an epoxide group or a moiety that decomposes under light irradiation to form radicals The copolymer of claim 1 comprising:

3. a) the at least one copolymerizable photoinitiator has the general formula A-(B): ｂ : [In the formula, A represents a substituent having a valence b, which includes at least one moiety that decomposes under light irradiation to form a radical; B represents a moiety containing an ethylenically unsaturated group; b is an integer of 1 to 3, preferably 1 or 2. The copolymer of claim 1 , wherein

4. General formula A-(B) ｂ In A represents a substituent having a valence b, which comprises at least one moiety that decomposes under irradiation to form a radical, the or each said moiety comprising a group selected from acetophenone, benzophenone, benzoin, anthraquinone, 9-fluorenone, anthrone, xanthone, thioxanthone, acridone, dibenzosuberone, or chromone; B represents a moiety containing a (meth)acrylate group or a (meth)acrylamide group; 4. The copolymer of claim 3, wherein b is 1 or 2.

5. a) the at least one copolymerizable photoinitiator has the formula (I): 【Chemistry 1】 [In the formula, R ０ is C １ -C ４ Alkyl, C ６ -C １８ aryl, or R ００ and R ００ has the following structure: 【Chemistry 2】 [During the ceremony, R ２ ~R ６ are independently H, OH, SH, halide, CN, C １ -C ４ Alkyl, C １ -C ４ Alkoxy, SR ８ , COOH, COOR ８ , N(R ８ ) ２ , or N(R ８ ) ３ Q is selected from; R ７ is H or C １ -C ４ is alkyl; Each R ８ are independently １ -C ６ Alkyl or C ６ -C １８ aryl; Q is halide, acetate, phosphate, sulfate or nitrate; However, the group R ２ ~R ６ j is a group: 【Transformation 3】 [where: j is an integer from 1 to 3, preferably 1 or 2; Each R' is independently H, C １ -C ４ Alkyl or C ６ -C １８ aryl; R″ is H or C １ is alkyl; R''' is H or C １ is alkyl; Sp is of the following type: 【Chemistry 4】 <During the ceremony, k is an integer from 1 to 10, l is an integer from 0 to 25; m is an integer from 1 to 10; n is an integer from 0 to 25; Each X is independently C ２ -C １２ Alkylene, C ３ -C １８ Cycloalkylene, or C ６ -C １８ arylene; Each Y is independently: 【Transformation 5】 and represents a spacer group of the formula: >, which is a divalent radical selected from the group consisting of is] have] 2. The copolymer of claim 1, comprising or consisting of at least one monomer according to

6. In formula (I), R ０ is C １ -C ４ Alkyl or C ６ is aryl; R ２ -R ６ are independently H, OH, C １ -C ４ Alkyl and C １ -C ４ alkoxy; R ７ is C １ is alkyl; Each R ８ are independently １ -C ６ alkyl; Each R' is independently H, C １ -C ４ Alkyl, or C ６ aryl, The copolymer of claim 5.

7. In formula (I), R ２ -R ６ are independently H and C １ -C ４ alkyl; Each R ８ is independent, C １ -C ４ selected from alkyl, The copolymer of claim 6.

8. The copolymer of claim 1 , wherein a) the at least one copolymerizable photoinitiator is a benzophenone (meth)acrylate.

9. 2. The copolymer of claim 1, wherein b) said at least one epoxy (meth)acrylate monomer is characterized by an equivalent weight of the sum of said epoxide groups and said (meth)acrylate groups of 100 to 700 g / eq, preferably 120 to 320 g / eq.

10. The copolymer of claim 1 , wherein the at least one epoxy (meth)acrylate monomer is an adduct of (meth)acrylic acid and a polyepoxide compound.

11. 11. The copolymer of claim 10, wherein the polyepoxide compound 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.

12. 11. The copolymer of claim 10, wherein the polyepoxide is a diglycidyl ether selected from the group consisting of diglycidyl ethers of aliphatic and cycloaliphatic diols; diglycidyl ethers based on bisphenol A; bisphenol F diglycidyl ethers; diglycidyl ethers based on polyalkylene glycols; and glycidyl ethers based on polycarbonate diols.

13. 1. A material crosslinkable under light irradiation, said material comprising: A copolymer according to any one of claims 1 to 12; and at least one ionic photoacid generator (PAG) Including, materials.

14. 1. A reactive hot melt composition that is crosslinkable under light irradiation, said composition comprising, based on the weight of the composition: i) 40 to 99.99% by weight of at least one copolymer according to any one of claims 1 to 12; ii) at least one ionic photoacid generator (PAG), 0.01 to 10 wt. %; iii) at least one tackifying resin, 0 to 60 wt. %; and iv) wax, 0 to 20% by weight; A composition comprising:

15. 15. A coating, adhesive, or sealant obtained by crosslinking under light irradiation of the reactive hot melt composition according to claim 14.

16. A hot melt pressure sensitive adhesive (HMPSA) obtainable by crosslinking under light irradiation of the reactive hot melt composition according to claim 14.

17. 15. An article (A) comprising a curable film of the hot melt composition of claim 14, wherein the film is disposed on a release liner and / or a carrier substrate.

18. 18. The article (A) according to claim 17, which is a label, a single-sided tape, a transfer tape, or a double-sided tape.

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