Copolymers and hot melt materials containing said copolymers

Abstract

The present application relates to a copolymer obtained by free radical polymerization, said copolymer comprising, based on the total weight of the monomers: 0.1 to 10% by weight of a) formula (I): [Formula 1] JPEG2026500307000018.jpg3764[In the formula, R 1 is NH, CH, S or O; R 2 ~R 9 are independently H, OH, SH, halide, CN, C1-C6 alkyl, C1-C6 alkoxy, C1-C 12 Alkoxyalkyl, COOH, SR 10 , COOR 10 , N(R 10 )2 or N(R 10 )Selected from 3Q; Each R 10 are independently C1-C6 alkyl or C6-C 18 aryl; and Q is halide, acetate, phosphate, sulfate, or nitrate. and the group R 2 ~R 9 at least one copolymerizable photoinitiator, where j is a group having ethylenic unsaturation, and j is an integer from 1 to 3, preferably 1 or 2; and 90 to 99.9% by weight of b) at least one ethylenically unsaturated nonionic monomer that does not have an epoxide group or a moiety that is decomposable under light irradiation to form radicals.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present disclosure relates to a copolymer that is crosslinkable under light irradiation, the copolymer being derived from an ethylenically unsaturated monomer, such as a monomer having (meth)acrylate functionality; and at least one copolymerizable photoinitiator having an ethylenically unsaturated group and a moiety that is decomposable under light irradiation to form radicals. The present disclosure also relates to a reactive hot melt material comprising the copolymer. The present disclosure further relates to a reactive hot melt pressure-sensitive adhesive material that may be useful in the production of tapes, labels, and decals. [Background technology]

[0002] Background to the invention As is 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 be in a molten or fluid state upon application of heat, and the compositions are applied to a given substrate in this fluid, molten state, but return to a solid or viscous liquid form upon cooling. The phases that form after the composition cools are intended to provide cohesive strength, toughness, and creep and heat resistance. 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 similarly solid or highly viscous liquids at room temperature that melt to a liquid or fluid state upon application of heat and are applied to a substrate in this fluid, molten state. After cooling again, the composition regains its original shape. The phase that forms after the composition cools but before curing is intended to provide initial or wet strength. After the applied composition is exposed to the required curing conditions, it hardens through a chemical crosslinking reaction. Before curing, the composition remains thermoplastic and can be remelted and resolidified, but once cured, the composition no longer possesses thermoplastic properties. The crosslinked composition is intended to provide cohesive strength, toughness, and creep and heat resistance. Generally, curable hot melt compositions can provide greater 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 workable bond to an adherend under light pressure at ambient temperature. In particular, 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 because it facilitates processing of the treated substrate. However, rapid curing of an applied reactive hot melt composition is not always desirable and can adversely affect the processability of the applied composition. For example, moisture-curing hot melt compositions can cure under ambient conditions and begin to develop strength immediately after application, potentially making them difficult to work with in production line equipment downstream of the applicator.

[0006] Thus, compositions that crosslink rapidly to provide cured strength clearly have a short working time. However, adhesive compositions that crosslink slowly have a longer service life but suffer from reduced strength, resulting in delays in subsequent commercial production. Therefore, there is a continuing effort in the art to develop reactive hot melt compositions that have a commercially desirable combination of wet strength, cured strength, and working life.

[0007] Several authors have focused on reactive hot melt compositions that can be cured under light irradiation, especially ultraviolet radiation. Photocuring offers a wide range of flexibility as a crosslinking method, since the user can determine the location and time of light irradiation and can regulate the exposure to radiation.

[0008] For example, US Pat. No. 3,661,618 (Firestone Fire and Rubber Company) provides a composition containing a polymer such as a cellulose derivative, a polyolefin, or a polyester, a liquid alkyl (meth)acrylate monomer, and a reactive monomer. After application of the adhesive, the monomer is crosslinked under high-energy particle radiation in the near absence of oxygen. However, the problem is that the monomeric (meth)acrylate is volatile and has an irritating effect. To obviate the disadvantages of a large proportion of free monomer in a photocurable composition, the introduction of copolymers with pendant photoreactive groups has been developed in the art.

[0009] EP 3 252 088 A1 (Henkel AG & Co.KgaA) states: In the first step, (i) a compound of formula (I): [ka] [In the formula, R 1 is H or CH3, and R 2 and R 3 are both H or both CH3, and n is an integer from 0 to 22. and (ii) at least one monomer comprising a pendant reactive functional group selected from cycloaliphatic epoxides, oxetanes, monosubstituted oxalanes, or mixtures thereof; and in a second step, reacting the mixture obtained from the first step with (iii) at least one cationic photoinitiator; and (iv) optionally further additives.

[0010] EP2960258 A1 (Henkel AG & Co. KgaA) discloses a method for producing a UV-curable acrylic copolymer, the method comprising: (a) polymerizing a monomer mixture containing, based on the weight of the mixture, (i) 40 to 95 wt. % of at least one (meth)acrylate monomer; (ii) 5 to 60 wt. % of at least one copolymerizable monomer selected from those having a glass transition temperature of a homopolymer thereof higher than −30° C.; and (iii) optionally, 0.5 to 20 wt. % of at least one copolymerizable functional monomer having a functional group selected from the group consisting of a hydroxyl group and a carboxyl group, to form an acrylic copolymer; and (b) reacting the acrylic copolymer with at least one monomer containing a UV-curable functional group in the presence of a catalyst to form a UV-curable acrylic copolymer, wherein the monomer containing a UV-curable functional group is a monomer containing a vinyl group and an epoxy group, preferably an epoxy-functionalized acrylate, more preferably a glycidyl ester of (meth)acrylic acid.

[0011] WO2021 / 225778 A1 (Henkel IP and Holding GmbH) describes a photocrosslinker that responds to ultraviolet light having a wavelength of 365 nm or more, and the photocrosslinker is represented by the following formula (I): [ka] [In the formula, R is H, C1~C 30 Alkyl, C1-C 30 Alkoxy, C1-C30 Acyloxy, C3-C 30 Allyloxy, halogen, or C1-C 30 is a thioether; R 1 is H or CH3; and X is optional, and if X is absent, then R is not H. It has a structure defined as:

[0012] Further disclosed is a hot melt pressure sensitive adhesive comprising a (meth)acrylate polymer incorporating a photocrosslinker represented by formula (I).

[0013] EP 1 469 036 B1 (Collano AG) describes a composition comprising a meltable, UV-crosslinkable polyacrylate, which comprises an oligomeric compound having a UV-crosslinkable functional group reactive with the polyacrylate. The UV-crosslinkable polyacrylate has the following formula: [ka] [In the formula, R 1 is an alkylene group, and R 2 is a hydrogen atom or a methyl group, and R 3 is an unsubstituted or substituted C1-C4 alkyl group or a phenyl group] It is obtained by copolymerization of the functional monomers.

[0014] EP-A-0 017 364 (Rohm & Haas) describes copolymers that may be used, inter alia, in adhesives and sealants. These copolymers contain 0.1 to 10% by weight of allylbenzoylbenzoate as a copolymerized photoinitiator. While these materials can be crosslinked using UV radiation, their reactivity to that radiation is considered too low, resulting in reduced curing efficiency, especially deep within the material layer. Furthermore, layers produced from the copolymers are not considered sufficiently adhesive for certain adhesive applications.

[0015] The low reactivity and inefficiency of crosslinked copolymers containing 0.01 to 5% by weight of copolymerizable 2-alkoxy-2-phenyl-2-benzoylethyl acrylate are also considered to be drawbacks of the teaching of US Patent No. 4,144,157 (Beiersdorf AG).

[0016] In practice, the poor curing efficiency of copolymers containing copolymerizable photoinitiators can be mitigated by using hot-melt compositions at lower coating weights or by increasing the irradiation dose. Furthermore, the poor curing efficiency is unfortunately attributed to the continued use of mercury-based UV systems for photoirradiating crosslinked polymers. Mercury lamps offer a broad spectral distribution, with short wavelengths promoting surface cure of the applied composition, while long wavelengths result in deeper cure. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] U.S. Patent No. 3,661,618 [Patent Document 2] European Patent Application Publication No. 3252088 [Patent Document 3] European Patent Application Publication No. 2960258 [Patent Document 4] International Publication No. 2021 / 225778 [Patent Document 5] International Publication No. 1469036 [Patent Document 6] European Patent Application Publication No. 0017364 [Patent Document 7] U.S. Patent No. 4,144,157 Summary of the Invention [Problem to be solved by the invention]

[0018] However, these solutions may be undesirable or practically impractical for certain applications. In particular, following the 2013 Minamata Convention on Mercury, the manufacture, import, or export of mercury lamps became illegal in January 2020. Therefore, there is a need in the art to develop copolymers containing copolymerizable photoinitiators that respond to UV radiation, an alternative source to mercury lamps, at practical coating weights and applicable doses. Developing copolymers containing copolymerizable photoinitiators that can be cured using ultraviolet light-emitting diodes (UV-LEDs) would certainly be advantageous, given that such systems offer advantages such as compactness, lack of fragility, temperature-independent output, and no lead or warm-up time, among others. [Means for solving the problem]

[0019] Description of the Invention According to a first aspect of the present disclosure, there is provided a copolymer obtained by free radical polymerization, said copolymer comprising, based on the total weight of monomers: a) 0.1 to 10% by weight of a compound of formula (I): [ka] [In the formula, R 1 is NH, CH, S or O; R 2 ~R 9 are independently H, OH, SH, halide, CN, C1-C6 alkyl, C1-C6 alkoxy, C1-C 12 Alkoxyalkyl, COOH, SR 10 , COOR 10 , N(R 10 )2 or N(R 10 )Selected from 3Q; Each R 10 are independently C1-C6 alkyl or C6-C 18 aryl; and Q is halide, acetate, phosphate, sulfate, or nitrate. at least one copolymerizable photoinitiator represented by base R 2 ~R 9 where j is: [ka] A group selected from 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; and Sp is the following type -[-{(X) k -Y} l -(X) m -]- or -[-{(X) k -Y} l -{(X) m -Y} n ]- [In the formula, 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 C2-C 12 Alkylene, C3-C 18 Cycloalkylene, or C6-C 18 arylene; and Each Y is: [ka] is a divalent group independently selected from the group consisting of represents a spacer group of at least one copolymerizable photoinitiator, subject to the proviso that b) 90 to 99.9% by weight of at least one ethylenically unsaturated nonionic monomer that does not have an epoxide group or a moiety that is decomposable under light irradiation to form radicals Includes:

[0020] In an important embodiment, the copolymer comprises, based on the total weight of the monomers: 0.1 to 5% by weight, preferably 0.1 to 2% by weight, of a portion a) of said at least one copolymerizable photoinitiator of formula (I); and 95 to 99.9% by weight, preferably 98 to 99.9% by weight, of the portion b) of said at least one ethylenically unsaturated nonionic monomer which does not have epoxide groups or moieties which can be decomposed by irradiation with light to form radicals Includes:

[0021] The or each copolymerizable photoinitiator of formula (I) incorporated into the copolymer in part a) is characterized as follows: R 1 is NH, S, or O, e.g., R 1 is S; and / or R 2 ~R 9 are independently selected from H, OH, C1-C4 alkyl, C1-C4 alkoxy, or C1-C8 alkoxyalkyl, or preferably, R 2 ~R 9 are independently selected from H or C1-C4 alkyl; and / or Each R' is independently selected from H, C1-C4 alkyl, or C6 aryl.

[0022] In certain embodiments, portion a) comprises at least one monomer selected from the group consisting of 9-oxo-3-(propan-2-yl)-9H-thioxanthen-2-ylpropen-2-oate, and N-ethyl-N-[(9-oxo-9H-thioxanthen-3-yl)methyl]prop-2-enamide.

[0023] In some embodiments, portion b) of the copolymer may contain both hard and soft ethylenically unsaturated monomers. In particular, the copolymer may contain, based on the total weight of portion b), 80 to 99 weight percent of bs) at least one ethylenically unsaturated monomer that, when homopolymerized, produces a homopolymer having a glass transition temperature (Tg) of less than 25° C., or preferably less than 20° C., and 1 to 20 weight percent of bh) at least one ethylenically unsaturated monomer that, when homopolymerized, produces a homopolymer having a glass transition temperature (Tg) of greater than 25° C., or preferably greater than 30° C.

[0024] Because the photoinitiator is incorporated into the copolymer backbone, harmful migration of the photoinitiator is prevented. Furthermore, copolymers as detailed above exhibit curability or crosslinking under UV irradiation from LED lights or arrays thereof. Such crosslinking can be achieved with low irradiation doses and therefore low energy consumption. Furthermore, a reversible color change can occur during crosslinking of the copolymer, providing an easy and observable method for verifying the crosslinking reaction.

[0025] The crosslinking efficiency of the described copolymers may be further improved by the use of amine synergists, which may also be copolymerized in some embodiments. Thus, in one embodiment, portion b) of the copolymer comprises 0.1 to 5 wt. %, preferably 0.1 to 2 wt. %, based on the total weight of the monomers, of b)iv) at least one tertiary amino(meth)acrylate. In yet another embodiment, not mutually exclusive with the one immediately above, portion b) of the copolymer comprises 0.1 to 5 wt. %, preferably 0.1 to 2 wt. %, based on the total weight of the monomers, of b)iv) at least one monomer selected from the group consisting of N-vinylcaprolactam (NVC), vinylmethyloxazolidinone (VMOX), N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, and N-vinylpyrrolidone.

[0026] According to a second aspect of the present disclosure, there is provided a material crosslinkable under light irradiation, said material comprising or consisting of a copolymer as defined herein above and in the appended claims.

[0027] The present disclosure further provides a reactive hot melt composition crosslinkable under light irradiation, the composition comprising, based on the weight of the composition, 20 to 100 wt. % of i) at least one copolymer as defined hereinabove and in the appended claims; 0 to 60 wt. % of ii) at least one tackifying resin; and 0 to 20 wt. % of iii) a wax.

[0028] Coatings, adhesives, or sealants obtained by crosslinking under light irradiation of the reactive hot melt materials defined herein are considered a further aspect of the present disclosure. Hot melt pressure sensitive adhesive (HMPSA) materials are an important aspect of this aspect.

[0029] The present disclosure further provides an article (A) comprising a curable film of the hot melt material defined above, the 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 explanation of the drawings]

[0030] [Figure 1] FIG. 1 shows a single-sided tape without a release liner according to an embodiment of the present invention. [Figure 2] FIG. 2 shows one embodiment of the article of the present invention, which can correspond to a single-sided tape or a label with a release liner. [Figure 3] FIG. 3 shows a transfer tape having one release liner according to an embodiment of the present invention. [Figure 4] FIG. 4 shows a transfer tape having two release liners according to an embodiment of the present invention. [Figure 5] FIG. 5 shows a double-sided tape having one release liner according to an embodiment of the present invention. [Figure 6]FIG. 6 shows a double-sided tape having two release liners according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] definition As used herein, the singular forms "a," "an," and "the" include plural references unless otherwise specified.

[0032] 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 elements, components, or method steps.

[0033] As used herein, the term "consisting of" excludes any components, materials, elements, or method steps not specified. For clarity, the term "comprising" includes "consisting of."

[0034] The terms "preferred," "preferably," "desirably," and "particularly" are used frequently herein to direct attention to embodiments of the present disclosure that may afford particular benefits, under certain circumstances. However, the recitation of one or more 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.

[0035] The word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word "exemplary" is intended to present concepts in a concrete manner.

[0036] As used throughout this application, the word "may" is used in a permissive, or possibly, sense rather than a required sense.

[0037] 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 any range obtained by combining any upper value or preferred value with a lower value or preferred value is also specifically disclosed, whether or not the resulting range is expressly stated in the context.

[0038] Furthermore, in accordance with standard understanding, weight ranges expressed as "0 to x" specifically include 0% by weight: for example, component or moiety a) or moiety b) herein, as defined by said range, may be absent from the material or may be present in the material in an amount up to x% by weight.

[0039] The term "based on total weight of monomers" refers to the total monomers of the copolymer. The weight ratio based on the weight of the monomers of part a) or part b) of the copolymer is specifically identified where applicable.

[0040] As used herein, room temperature is 23°C plus or minus 2°C.

[0041] Molecular weights given herein can be determined by gel permeation chromatography (GPC) using polystyrene calibration standards, as performed in accordance with ASTM 3536.

[0042] As used herein, the term softening point (°C) used in reference to the waxes and tackifying resins herein is the Ring & Ball softening point, measured in accordance with ASTM E28, unless otherwise indicated.

[0043] When referred to, the calculated glass transition temperature ("T") of the polymer or copolymer is g ") is the Fox equation:

number

[0044] The actual glass transition temperature (T g ) can be measured by differential scanning calorimetry (DSC) according to the methodology of Deutsches Institut für Normung (DIN) 11357.

[0045] Viscosity of materials described herein is measured using a Brookfield DVII Viscometer at the specified temperature and 50% relative humidity (RH) with Spindle 27 unless otherwise specified. The viscometer is calibrated annually and verified by inspection. Calibration is at 23°C and a shear rate of 1 s -1 Measurements of the materials of the present invention are carried out using a parallel plate PP20 with standard liquids of known viscosity ranging from 1 to 50,000 cps. -1 The experiment was carried out using parallel plates PP20 at different shear rates.

[0046] As used in the art, the term "pressure-sensitive adhesive" refers to an adhesive material that has the following properties: (1) persistent tack; (2) adhesion requiring no more than finger pressure; (3) sufficient holding power to the substrate; and (4) sufficient cohesive strength to be removed cleanly from the substrate.

[0047] As used herein, the term "hot melt" refers to a material that is substantially non-flowable at room temperature, but that changes to a flowable state at elevated application temperatures, e.g., 100°C to 180°C. However, the materials of the present invention exhibit "cold flow," which refers to the material's tendency to distort or viscous flow under pressure, especially finger pressure, at room temperature. The material does not exhibit a liquid-to-solid transition and generally does not return to its original dimensions upon removal of pressure.

[0048] As used herein, the term "release liner" refers to a thin, flexible sheet that can be placed in intimate contact with the surface of a pressure-sensitive adhesive and then removed without damaging the adhesive coating.Exemplary materials that release liners can contain or be made of include silicone; polyethylene; polypropylene; polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); cellulose acetate; polyvinyl chloride; polyvinyl fluoride; and paper substrates coated or laminated with the aforementioned thermoplastic resins.For completeness, coated paper or thermoplastic materials are often coated with silicone or treated with a release agent to provide 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 occur. The release liner thereby serves several functions, including preventing contamination of the material, facilitating handling, providing support, and transmitting information or identifying data.

[0050] As used herein, the term "carrier" refers to a material that can coat and stabilize a curable film of a hot melt pressure-sensitive adhesive material. Carriers can add thickness to an article to improve handling. Carrier substrates differ from release liners in that they cannot be removed from the curable film without adversely affecting the integrity of the curable film. Carriers can be flexible and typically can be selected from polymeric films, metal foils, foams, fabrics, and combinations thereof. For example, the carrier substrate can be selected from the group consisting of polyester, polypropylene, polyethylene, foam, and paper.

[0051] As used herein, the term "transfer coating" refers to a layer or film of pressure-sensitive adhesive that exists without a support.

[0052] As used herein, the term "application temperature" refers to the temperature at which the viscosity of the material is substantially fluid and can be placed as a fluid onto a substrate by contact or non-contact techniques.

[0053] As used herein, the term "free radical initiator" refers to any chemical species that, when exposed to sufficient energy, such as in the form of light or heat, breaks down into two parts, each of which has no charge but at least one unpaired electron. Thus, upon exposure to heat, a thermal free radical initiator creates a free state. Additionally, known thermal free radical initiators include, but are not limited to, peroxide compounds, azo compounds, and persulfate compounds.

[0054] As used herein, the term "photoinitiator" refers to a compound that is activated by irradiation with an energy-carrying active beam, such as electromagnetic radiation. Specifically, "free radical photoinitiator" herein refers to a photoactive compound that generates free radicals, which can initiate polymerization or reactions by adding to C=C double bonds present in the composition. Such free radical photoinitiators are typically classified as Norrish Type I and Norrish Type II photoinitiators. Norrish Type I radical photoinitiators undergo a Norrish Type I reaction when exposed to actinic radiation, which is defined by IUPAC as the α-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 first photoproduct. Norrish Type II radical photoinitiators undergo a Norrish Type II reaction when exposed to actinic radiation, which is defined by IUPAC as the photochemical abstraction of γ-hydrogen by an excited carbonyl compound, producing a 1,4-biradical as the primary photoproduct.

[0055] As used herein, the term "monomer" refers to a substance that can undergo a polymerization reaction to provide building blocks for the chemical structure of a polymer. As used herein, the term "monofunctional" refers to having one polymerizable moiety. As used herein, the term "multifunctional" refers to having one or more polymerizable moieties.

[0056] As used herein, a "solvent" is a substance that has the ability to dissolve other substances and form a homogeneous solution such that the solvent and dissolved substances do not undergo chemical changes during dissolution. Solvents can be either polar or non-polar.

[0057] As used herein, the term "equivalents (eq.)," as common in chemical notation, relates to the relative number of reactive groups present in a reactant.

[0058] As used herein, the term "equivalent weight" refers to the molecular weight divided by the number of associated functional groups. Thus, "epoxy equivalent weight" (EEW) means the weight in grams of a resin containing one equivalent of epoxide.

[0059] As used herein, the term "epoxide" refers to a compound characterized by having at least one cyclic ether group, i.e., a compound in which an ether oxygen atom is bonded to two adjacent carbon atoms to form a ring structure. The term is intended to include monoepoxide compounds, polyepoxide compounds (having two or more epoxide groups), and epoxide-terminated prepolymers. The term "monoepoxide compound" is intended to refer to an epoxide compound having one epoxide group. The term "polyepoxide compound" is intended to refer to an epoxide compound having at least two epoxide groups. The term "diepoxide compound" is intended to refer to an epoxide compound having two epoxide groups.

[0060] The epoxides may be unsubstituted or inertly substituted. Exemplary inert substituents include chlorine, bromine, fluorine, and phenyl.

[0061] As used herein, "(meth)acryl" is an abbreviation for "acryl" and / or "methacryl." Thus, the term "(meth)acrylamide" collectively refers to acrylamide and methacrylamide.

[0062] As used herein, "C1-C n An "alkyl" group refers to a monovalent group containing from 1 to n carbon atoms, is a radical of an alkane, and includes straight-chain and branched organic groups. Thus, "C1-C 18 An "alkyl" group refers to a monovalent group containing 1 to 18 carbon atoms, is a radical of an alkane, and includes straight-chain and branched organic groups. Generally, alkyl groups contain 1 to 12 carbon atoms (C1-C 12It should be noted that alkyl groups containing 1 to 8 carbon atoms (C1-C8 alkyl) are preferred. 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. If applicable to a given moiety (R), the tolerance for one or more non-halogen substituents in an alkyl group is set forth in the specification.

[0063] As used herein, "C1-C 18 The term "hydroxyalkyl" refers to a HO-(alkyl) group having from 1 to 18 carbon atoms, where the point of attachment of the substituent is through the oxygen atom, and the alkyl group is defined above.

[0064] "Alkoxy group" refers to a monovalent group represented by -OA, where A is an alkyl group. Non-limiting examples include methoxy, ethoxy, and isopropyloxy groups. As used herein, "C1-C 12 The term "alkoxyalkyl" refers to an alkyl group having an alkoxy substituent, as defined above, where the portion (alkyl-O-alkyl) contains a total of 1 to 12 carbon atoms. Such groups include methoxymethyl (-CHOCH), 2-methoxyethyl (-CHCHOCH), and 2-ethoxyethyl. Similarly, as used herein, "C-C 18 The term "alkoxyaryl" refers to an aryl group having an alkoxy substituent, as defined above, and means that the moiety (aryl-O-alkyl) contains from 7 to 18 total carbon atoms.

[0065] As used herein, "C2-C 12The term "alkylene" is defined as a saturated divalent hydrocarbon group having 2 to 12 carbon atoms. Generally, in this disclosure, such alkylene groups can be unsubstituted or substituted with one or more halogens. Specifically, within the monomer of formula (I) below, such alkylene groups (X) can be optionally substituted with one or more groups selected from halogens, OH, or COOH.

[0066] "C3-C 18 The term "cycloalkyl" is understood to mean a saturated monocyclic or polycyclic hydrocarbon group having 3 to 18 carbon atoms. In the present invention, such cycloalkyl groups may be unsubstituted or substituted with one or more halogens. If applicable to a given moiety (R), the tolerance for one or more non-halogen substituents in a cycloalkyl group is described in the specification. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantane, and norbornane.

[0067] As used herein, "C3-C 18 "Cycloalkylene" means a divalent group formed by removing two hydrogen atoms from one or more rings of a cycloalkyl group having 3 to 18 carbon atoms.

[0068] As used herein, the term "C-C alkyl group" used alone or as part of a larger moiety such as an "aralkyl group" is used interchangeably with "C-C alkyl group." 18"Aryl" groups refer to monocyclic, bicyclic, and tricyclic ring systems, where the monocyclic ring system is aromatic or at least one ring of the bicyclic or tricyclic ring system is aromatic. Bicyclic and tricyclic ring systems include benzo-fused 2-3 membered carbocyclic rings. In the present invention, such aryl groups can be unsubstituted or substituted with one or more halogens. If applicable to a given moiety (R), the tolerance for one or more non-halogen substituents in an aryl group is described in the specification. Exemplary aryl groups include phenyl; (C1-C4) alkylphenyl such as tolyl and ethylphenyl; indenyl; naphthalenyl, tetrahydronaphthyl, tetrahydroindenyl; tetrahydroanthracenyl, and anthracenyl. Additionally, phenyl groups tend to be preferred.

[0069] As used herein, "C6-C 18 "Arylene" means a divalent group formed by removing two hydrogen atoms from one or more rings of a cycloalkyl group having 3 to 18 carbon atoms. Generally, in this disclosure, such arylene groups can be unsubstituted or substituted with one or more halogens.

[0070] As used herein, "C2-C 20 "Alkenyl" refers to 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. If applicable to a given moiety (R), the tolerance for one or more non-halogen substituents in an alkenyl group is described in the specification. The term "alkenyl" also includes groups having "cis" and "trans" configurations, or alternatively, "E" and "Z" configurations, as will be understood by those skilled in the art. However, generally, alkenyl groups having 2 to 10 carbon atoms (C 2-10 ) or 2 to 8 pieces (C 2-8 It should be noted that unsubstituted alkenyl groups containing C-C are preferred. 12Examples of alkenyl groups are:-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=CHCH 3; -CH2CH2CH2CH=CH2; -C(=CH2)CH2CH2CH3; -C(CH3)=CHCH2CH3; -CH(CH3)CH=CHCH; -CH(CH3)CH2CH=CH2; -CH2CH=C(CH3)2; 1-cyclopent-1-enyl; 1-cyclopent-2-enyl; 1-cyclopent-3-enyl; 1-cyclohex-1-enyl; 1-cyclohex-2-enyl; and 1-cyclohexyl-3-enyl.

[0071] As used herein, "alkylaryl" refers to an alkyl-substituted aryl group, both groups being defined above. Additionally, as used herein, "aralkyl" refers to an alkyl group substituted with an aryl group, as defined above.

[0072] As used herein, the term "hetero" refers to groups or moieties that include one or more heteroatoms, such as N, O, Si, and S. Thus, for example, "heterocyclic" refers to a cyclic group having, for example, N, O, Si, or S as part of the ring structure. "Heteroalkyl," "heterocycloalkyl," and "heteroaryl" moieties are alkyl, cycloalkyl, and aryl groups, as defined above, that include, respectively, N, O, Si, or S as part of their structure.

[0073] As used herein, the term "equivalent weight" refers to the molecular weight divided by the number of functional groups involved. Thus, "epoxy equivalent weight" (EEW) means the weight in grams of a resin containing one equivalent of epoxy.

[0074] Materials and compositions of the present invention may be defined herein as being "substantially free" of a particular compound, element, ion, or other similar component. The term "substantially free" is intended to mean that the compound, element, ion, or other similar component has not been intentionally added to the material or composition, is present in trace amounts at most, and does not (negatively) affect the desired properties of the material or composition. An exemplary trace amount is less than 1000 ppm by weight of the material or composition. The term "substantially free" includes embodiments in which the particular compound, element, ion, or other similar component is completely absent from the material or composition, or is not present in amounts measurable by techniques commonly used in the art.

[0075] 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 in only trace amounts, at most, that do not (adversely) affect the desired properties of the composition.

[0076] Detailed Description of the Invention The following disclosure describes the monomers that make up each portion (a) and (b) of the copolymer.

[0077] a) Copolymerizable photoinitiator The copolymers of the present disclosure have the formula (I): [ka] [In the formula, R 1 is NH, CH, S or O; R 2 ~R 9 are independently H, OH, SH, halide, CN, C1-C6 alkyl, C1-C6 alkoxy, C1-C 12 Alkoxyalkyl, COOH, SR 10 , COOR 10 , N(R 10 )2 or N(R 10 )Selected from 3Q; Each R10 are independently C1-C6 alkyl or C6-C 18 aryl; and Q is halide, acetate, phosphate, sulfate, or nitrate. a) at least one copolymerizable photoinitiator according to base R 2 ~R 9 where j is: [ka] A group selected from 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; and Sp is the following type -[-{(X) k -Y} l -(X) m -]- or -[-{(X) k -Y} l -{(X) m -Y} n ]- [In the formula, 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 C2-C 12 Alkylene, C3-C 18 Cycloalkylene, or C6-C 18 arylene; and Each Y is: [ka] is a divalent group independently selected from the group consisting of represents a spacer group.

[0078] In one embodiment, the group R of one or each copolymerizable photoinitiator according to formula (I) contained in the copolymer 2 ~R 9 j is as follows: [ka] A group selected from 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; and Sp is of the following type: -[-{(X) k -Y} l -(X) m -]- or -[-{(X) k -Y} l -{(X) m -Y} n ]- wherein k, l, m, n, X, and Y are as defined above. represents a spacer group.

[0079] Within formula (I), the following preferred embodiments may be mentioned: these preferred embodiments are independent of each other but are not mutually exclusive, and therefore said preferred embodiments may be combined in any way. R 1 is preferably NH, S or O, for example R 1 is S; R 2 ~R 9 are preferably independently selected from H, OH, C1-C4 alkyl, C1-C4 alkoxy, or C1-C8 alkoxyalkyl, more preferably independently selected from H or C1-C4 alkyl; Each R' is preferably independently selected from H, C1-C4 alkyl, or C6 aryl, more preferably independently selected from H, C1-C2 alkyl, or C6 aryl; k is preferably an integer of 1 to 5; l is preferably an integer of 0 to 10; m is preferably an integer of 1 to 5; n is preferably an integer from 0 to 10; and Each X is preferably independently selected from C2-C8 alkylene, C3-C6 cycloalkylene, or C6 arylene.

[0080] Exemplary copolymerizable photoinitiators according to Formula (I) include, but are not limited to, 9-oxo-3-(propan-2-yl)-9H-thioxanthen-2-ylpropen-2-oate and N-ethyl-N-[(9-oxo-9H-thioxanthen-3-yl)methyl]prop-2-enamide.

[0081] The decomposition of said moieties forms radicals which cause crosslinking of the copolymer, thus forming a crosslinked product. The amount of said at least one copolymerizable photoinitiator of part a) in the copolymer must be sufficient to realize sufficient crosslinking capacity of the resulting copolymer upon irradiation, but not so high as to promote deterioration of the adhesive properties or breathability of the final crosslinked product.

[0082] The copolymer of the present disclosure should comprise 0.1 to 10 wt. % of a) said at least one copolymerizable photoinitiator according to formula (I), based on the total weight of the monomers. The copolymer desirably comprises 0.1 to 5 wt. %, for example 0.1 to 2 wt. % of a) said at least one copolymerizable photoinitiator, based on the total weight of the monomers.

[0083] b) Ethylenically unsaturated nonionic monomers The copolymers of the present disclosure comprise 90.0 to 99.9 wt. % of b) at least one ethylenically unsaturated nonionic monomer, based on the total weight of the monomers, that does not have an epoxide group or a moiety that decomposes upon irradiation to form radicals. For example, the copolymers may comprise 95.0 to 99.9 wt. % or 98.0 to 99.9 wt. % of b) at least one ethylenically unsaturated nonionic monomer that does not have an epoxide group or a moiety that decomposes upon irradiation to form radicals. Such a monomer can, in principle, be any ethylenically unsaturated nonionic monomer. However, the present invention is particularly applicable to compositions in which at least 70 wt. % and preferably at least 75 wt. % of the copolymer's portion b) is a (meth)acrylate monomer.

[0084] b) i) Aliphatic and alicyclic (meth)acrylate monomers The copolymer has the formula BI: H2C=CG a CO2R a (BI) [In the formula, G a is hydrogen, halogen, or a C1 alkyl group; and R a is 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; or C2-C 12 alkynyl] b) i) at least one (meth)acrylate monomer represented by the formula:

[0085] For example, R a is C1-C 18 Alkyl, C1-C 12 Hydroxyalkyl; C2-C 18 Heteroalkyl, C3-C18 cycloalkyl; C2-C8 heterocycloalkyl; C2-C8 alkenyl, or C2-C8 alkynyl, and preferably the monomer b)i) is selected from R a C1-C 18 Alkyl, C1-C6 hydroxyalkyl, or C3-C 18 It may be selected from cycloalkyl.

[0086] Examples of (meth)acrylate monomers b)i) according to formula (BI) 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.

[0087] b) ii) Aromatic (meth)acrylate monomers The copolymer has the formula BII: H2C=CG b CO2R b (BII) [In the formula, G b may be hydrogen, halogen, or a C1 alkyl group, and R b is C6-C 18 Aryl, C1-C9 heteroaryl, C7-C 18 Alkoxyaryl, C7-C 18 Alkaryl, or C7-C 18 aralkyl] b) ii) may comprise at least one (meth)acrylate monomer represented by the formula:

[0088] Exemplary (meth)acrylate monomers b)ii) according to formula (BII) that can be used alone or in combination include, but are not limited to, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and phenoxypropyl (meth)acrylate.

[0089] b) iii) (Meth)acrylate-functionalized oligomers The copolymer may comprise b)iii) at least one (meth)acrylate-functionalized oligomer selected from the group consisting of (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.

[0090] The oligomer b)iii) may have one or more acrylate and / or methacrylate groups attached to the oligomer backbone, and these (meth)acrylate functionalities may be located at the ends of the oligomer and / or distributed along the oligomer backbone. Preferably, the or each (meth)acrylate-functionalized oligomer b)iii) reacted as a monomer in obtaining the copolymer has two or more (meth)acrylate functionalities per molecule and / or a weight average molecular weight (Mw) in the range of 300 to 1000 Daltons.

[0091] b) iv) Nitrogen (N-) functionalized ethylenically unsaturated monomers The copolymer may, in certain embodiments, comprise one or more nitrogen (N)-functionalized ethylenically unsaturated monomers. The nitrogen-functional group may be a nitrile or have an imidic, amidic, or amine nitrogen atom.

[0092] Exemplary nitrile monomers include, but are not limited to, acrylonitrile and methacrylonitrile. Exemplary maleimide monomers include, but are not limited to, maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, and cyclohexylmaleimide. Exemplary (meth)acrylamides include acryloylmorpholine, diacetone (meth)acrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, Nt-butyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-cyclohexyl (meth)acrylamide, N-octyl (meth)acrylamide, Nt-octyl (meth)acrylamide, N-dodecyl (meth)acrylamide, N-benzyl (meth)acrylamide, N-(hydroxymethyl)acrylamide, N-isobutoxymethyl acrylamide, N-butoxymethyl acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acryl ... Examples of suitable acrylamides include acrylamide, N,N-propyl(meth)acrylamide, N,N-dibutyl(meth)acrylamide, N,N-dihexyl(meth)acrylamide, N,N-dimethylaminomethylacrylamide, N,N-dimethylaminoethylacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminohexylacrylamide, N,N-diethylaminomethylacrylamide, N,N-diethylaminoethylacrylamide, N,N-diethylaminopropylacrylamide, N,N-dimethylaminohexylacrylamide, N-hydroxymethyl(meth)acrylamide, acrylamido-2-methylpropanesulfonic acid, and N,N'-methylenebisacrylamide.

[0093] In one embodiment, the copolymer comprises at least one amino(meth)acrylate monomer. As used herein, the term "amino(meth)acrylate" refers to a derivative of methacrylic or acrylic acid having a primary, secondary, or tertiary amino group, which may be linear, branched, or part of an alicyclic or aromatic group. Desirably, the at least one amino(meth)acrylate monomer should be a tertiary amino(meth)acrylate, particularly an N,N-dialkylaminoalkyl(meth)acrylate. Exemplary monomers may include N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl methacrylate, and N,N-dimethylaminopropyl acrylate.

[0094] In an important embodiment, the copolymer comprises 0.1 to 5 wt. %, e.g., 0.1 to 2 wt. %, of at least one tertiary amino(meth)acrylate, based on the total weight of the monomers. Without intending to be bound by theory, the tertiary amine functional group provides an active hydrogen donor site for the excited triplet state of the copolymerized photoinitiator. Furthermore, the tertiary amine may function to reduce oxygen inhibition of the crosslinking reaction: oxygen reacts rapidly with free radicals generated upon photoinitiation of the copolymer to form non-reactive peroxy radicals, whereas the tertiary amine can react with said peroxy radicals and convert them to reactive alkylamino radicals.

[0095] In yet another embodiment, not intended to be mutually exclusive with the above embodiment, the copolymer includes at least one vinyl monomer having a nitrogen heterocyclic structure. Exemplary heterocyclic structures may have five or six members and may include oxygen atoms in addition to nitrogen; the five- or six-membered ring may represent, for example, a pyridine, pyrimidine, pyridazine, imidazoline, imidazole, oxazoline, oxazole, or morpholine ring. In an important embodiment, the copolymer includes at least one monomer selected from the group consisting of N-vinylcaprolactam (NVC), vinylmethyloxazolidinone (VMOX), N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, and N-vinylpyrrolidone in an amount ranging from 0.1 to 5 wt %, e.g., 0.1 to 2 wt %, based on the total weight of the monomers. The use of vinylmethyloxazolidinone (VMOX) is particularly preferred due to its function as a synergist in Norrish Type II photoinitiation reactions.

[0096] b) v) Further ethylenically unsaturated nonionic monomers The present invention does not preclude the inclusion in the copolymer of additional ethylenically unsaturated nonionic monomers not conforming to the definitions of b)i)-iv) set forth herein, provided, however, that the addition of such additional monomers should be bounded by the proviso that said additional monomer b)v) does not exceed 30% by weight of portion b) of the copolymer.

[0097] Without intending to limit the invention, such additional ethylenically unsaturated nonionic 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 and styrene sulfonic acid; vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and Shell Chemical vinyl esters such as the VEOVA™ series of monomers available from the Company; vinyl and vinyl diene halides; vinyl ethers such as vinyl ethyl ether; vinyl ketones including alkyl vinyl ketone, cycloalkyl vinyl ketone, aryl vinyl ketone, aryl alkyl vinyl ketone, and aryl cycloalkyl vinyl ketone; aromatic or heterocyclic aliphatic vinyl compounds; 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, glycol Poly(meth)acrylates of alkane polyols such as serine 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 ("ECIPMA").

[0098] Representative examples of other ethylenically unsaturated polymerizable nonionic monomers b) and v) include, without limitation, ethylene glycol dimethacrylate (EGDMA); acrylic acid, methacrylic acid, and fumaric acid; fumaric anhydride, maleic anhydride, and itaconic anhydride; and 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, without limitation, 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, without limitation, compounds such as styrene, α-methylstyrene, vinyltoluene, tert-butylstyrene, 2-vinylpyrrolidone, 5-ethylidene-2-norbornene, and 1-, 3-, and 4-vinylcyclohexene.

[0099] For the sake of completeness, the above copolymerizable acid monomers should normally be used in the form of their free acids, although it is not excluded that the constituent acid groups of the monomers may be partially or completely neutralized with a suitable base, provided that their participation in the copolymerization is not impaired.

[0100] The ethylenically unsaturated monomers comprising part b) of the copolymer may, in some embodiments, include both "soft" and "hard" monomers. For example, the copolymer may include, based on the total weight of part b), 80 to 99 weight percent of bs) at least one ethylenically unsaturated monomer that, when homopolymerized, produces a homopolymer having a glass transition temperature (Tg) of less than 25° C., and 1 to 20 weight percent of bh) at least one ethylenically unsaturated monomer that, when homopolymerized, produces a homopolymer having a glass transition temperature (Tg) of greater than 25° C.

[0101] In particular, the copolymer may comprise 80 to 99% by weight, for example 85 to 99% by weight or 85 to 95% by weight, based on the total weight of part b), bs) at least one ethylenically unsaturated monomer that, when homopolymerized, forms a homopolymer having a glass transition temperature (Tg) of less than 20°C, and 1 to 20% by weight, for example 1 to 15% by weight or 5 to 15% by weight, bh) at least one ethylenically unsaturated monomer that, when homopolymerized, forms a homopolymer having a glass transition temperature (Tg) of greater than 30°C.

[0102] The soft (bs) and hard (bh) monomers may be selected from among the aforementioned monomers b)i) through b)v) based on available data, calculations, or measurements of glass transition temperatures (Tg).

[0103] Exemplary soft monomers include, but are not limited to, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, secbutyl acrylate, hexyl acrylate, hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-propylheptyl acrylate, isodecyl acrylate, dodecyl acrylate, cyclohexyl acrylate, benzyl acrylate, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), pentadiene, and 2-chloro-1,3-butadiene. Preferably, one or more of n-butyl acrylate, 2-ethylhexyl acrylate, and 2-propylheptyl acrylate are used as the soft monomer.

[0104] Exemplary hard monomers h) include, but are not limited to, methyl methacrylate, isopropyl methacrylate, tert-butyl acrylate, methacrylic acid, acrylic acid, fumaric acid, vinyl acetate, benzyl methacrylate, α-methylstyrene, and bromostyrene. It may be preferable to use one or more of methacrylic acid, acrylic acid, and fumaric acid as the hard monomer.

[0105] Copolymer formation by free radical polymerization The copolymers of the present disclosure are prepared by free radical polymerization. As recognized by experienced practitioners, free radical polymerization consists of three stages: first, the decomposition of an initiator generates active free radicals with unpaired electrons, which react with the monomers present to generate an initiating radical chain; second, the initiating radical chain attacks a second monomer molecule, transferring its active center to the attacked molecule, thus repeating the process to grow the polymer chain; and finally, third, the termination of the macromolecular chain growth, which terminates the polymerization by disabling the active center. The two most common termination mechanisms in radical polymerization are coupling and deprotonation.

[0106] Free radical polymerization may be carried out in bulk, emulsion, suspension, or solution. While not intending to limit the present disclosure, the copolymer is preferably prepared by free radical solution polymerization, which means that a solution of monomers in a solvent capable of dissolving the copolymer is polymerized by free radical polymerization in the presence of a polymerization initiator. The concentration of monomers in the solution may vary, but the weight ratio of monomer to solvent is typically in the range of 1:20 to 2:1, e.g., 1:2 to 1.5:1.

[0107] The free radical solution polymerization reaction should desirably be carried out in the presence of a polar solvent having a boiling point of at least 20°C, e.g., at least 30°C or at least 40°C, measured at 1 atmosphere (1.01325 bar). 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; (C1-C8) alkyl acetates, ethoxylated alkyl esters, methyl ... Esters such as glycol acetate, dimethyl glutarate, dimethyl malate, dipropyl oxalate, ethyl lactate, benzyl benzoate, butyl octyl 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 one exemplary embodiment, the polymerization reaction is carried out in the presence of a (C1-C8) alkyl acetate, particularly ethyl acetate.

[0108] As noted above, free radical polymerization is initiated 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 is activated by thermal energy to generate its radicals, for example, by heating or irradiation in the infrared or microwave wavelength range. The polymerization composition typically contains 0.1 to 1 wt. % of the at least one radical-generating thermal initiator, for example, 0.1 to 0.5 wt. %, based on the total weight of the polymerizable monomers.

[0109] While not intending to limit the invention, an exemplary class of radical-generating thermal initiators suitable for use in the present invention are organic peroxides selected from the following: cyclic peroxides; diacyl peroxides; dialkyl peroxides; hydrogen peroxide; peroxycarbonates; peroxydicarbonates; peroxyesters; and peroxyketals.

[0110] Certain peroxides, such as dialkyl peroxides, have been disclosed as useful initiators, inter alia, in U.S. Patent No. 3,419,512 (Lees) and U.S. Patent No. 3,479,246 (Stapleton), and may indeed be useful in the present invention, with hydrogen peroxide representing a preferred class of initiators in the present invention. Furthermore, while hydrogen peroxide itself can be used, the most desirable polymerization initiators are organic peroxides. For completeness, the definition of hydrogen peroxide includes materials that decompose or hydrolyze to form organic hydrogen peroxides in situ, such as organic peroxides or organic peresters; examples of such peroxides and peresters are cyclohexyl peroxide and hydroxycyclohexyl peroxide, respectively, and t-butyl perbenzoate.

[0111] In an embodiment of the present invention, the radical-generating thermal initiator has the formula: R p OOH [In the formula, R p is an aliphatic or aromatic group containing up to 18 carbon atoms, preferably R p is C1-C 12 Alkyl, C6-C 18 Aryl, or C7-C 18 an aralkyl group] The composition comprises or consists of at least one hydroperoxide compound represented by the formula:

[0112] Exemplary peroxide initiators include the following, which may be used alone or in combination: 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 hydroperoxide. 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.

[0113] Although not intended to limit the present invention, further exemplary classes of radical-generating thermal initiators suitable for use in the present invention are azo polymerization initiators selected from, for example, azonitriles, azoesters, azoamides, azoamidines, azoimidazolines, and macroazo initiators.

[0114] Representative examples of suitable azo polymerization initiators 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)propionamine] 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, available from Wako Pure Chemical Industries Ltd.); and 4,4'-Azobis(4-cyanopentanoic acid) polyethylene glycol polymer (VPE-0201, available from Wako Pure Chemical Industries Ltd.).

[0115] Redox initiators, which are combinations of oxidizing and reducing agents, 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, hydrogen peroxide, peroxycarbonates, peroxydicarbonates, peroxide esters, and peroxide ketals. 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, particularly cobalt(II) salts and iron(II) salts such as iron(II) sulfate, iron(II) ammonium sulfate, or iron(II) phosphate; dihydroxymaleic acid; benzoin; ascorbic acid; and reducing sugars such as sorbose, glucose, fructose, and / or dihydroxyacetone.

[0116] It is believed that, other than initiators, free radical polymerizations can be carried out in the presence of chain transfer agents, which transfer free radicals and reduce the molecular weight of the resulting polymer and / or control chain growth in the polymerization. When added, chain transfer agents should constitute 0.01 to 1 weight percent based on the total weight of polymerizable monomers.

[0117] The copolymer production process is preferably carried out so that the number average molecular weight (Mn) of the copolymer is in the range of 50,000 to 500,000 daltons, for example, 75,000 to 300,000 daltons or 100,000 to 250,000 daltons. The amount of polymerization initiator and any chain transfer agent present will determine the number average molecular weight of the (co)polymer, although the choice of solvent may also be important.

[0118] While not intending to limit the invention, typical polymerization conditions include temperatures ranging from 0°C to 175°C, e.g., 25°C to 125°C or 50°C to 100°C. The polymerization pressure is generally not critical, and therefore the polymerization can be carried out under subatmospheric, atmospheric, or superatmospheric pressures. Aside from pressure, polymerization can be carried out under oxygen exclusion conditions, if desired, and the reaction vessel can be blanketed with an inert, dry gas such as, for example, nitrogen, helium, and argon.

[0119] For completeness, it is understood that the polymerizations of the present invention may be carried out as a batch or semi-batch procedure, or a continuous procedure. As will be understood 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 a reaction vessel, and most or all of the polymerization initiator is added to the reaction vessel during the course of polymerization. In a semi-batch procedure, at least a portion, up to all of the polymerization initiator and solvent, are charged to the reaction vessel initially; a small portion of the monomers may be charged as well, but most of the monomers to be polymerized are added to the reaction vessel during the course of polymerization. In a continuous process, the monomers, polymerization initiator, and, optionally, solvent are continuously added to the reaction vessel, and the resulting polymer is continuously discharged from the polymerization vessel.

[0120] In carrying out the polymerizations of the present invention, it is preferred to carry out the polymerization in a semi-batch manner, in particular by adding to the reaction vessel at least 75% by weight of the total weight of the monomers to be polymerized during the polymerization reaction.

[0121] There is no particular intention to limit the timing at which the different functional monomers of the copolymer (portions a) and b) are introduced into the polymerization procedure. The monomers may be fed to the polymerization vessel in a fixed molar ratio at the beginning of the polymerization (in the case of a batch process) or throughout the polymerization procedure (in the case of semi-batch and continuous processes). Alternatively, the molar ratio of the monomer species may be varied over the course of the polymerization, which is intended to include embodiments in which only monomers of portion a) or, conversely, only monomers of portion b) are added to the polymerization vessel during the polymerization. One skilled in the art can determine the appropriate molar ratio based on the desired shape or randomness of the copolymer and the reactivity ratios of the monomers.

[0122] The copolymer reaction product may be isolated and purified using suitable methods known in the art, such as extraction, evaporation, crystallization, distillation, chromatography, etc. When free-radical solution polymerization is used, the copolymer is most conveniently isolated by distillation of the solvent and unreacted starting materials under reduced pressure. If it is intended to store the (optionally purified) copolymer as prepared, the polymer should be placed in an airtight and moisture-proof container. The storage container must not be transparent to light irradiation.

[0123] Hot Melt Materials As mentioned above, the present disclosure also provides a reactive hot melt material, particularly as a reactive hot melt adhesive material, comprising or consisting of the copolymer described above. For clarity, it is stated that in certain embodiments, the copolymer may be used alone as a reactive hot melt material without further additives. Thus, a reactive hot melt material may be provided that comprises, based on the weight of the material, i) 40 to 100 wt. % of at least one copolymer as defined above and in the appended claims, ii) 0 to 30 wt. % of at least one tackifying resin, and iii) 0 to 30 wt. % of a wax.

[0124] The pressure-sensitive adhesive material of the present invention may comprise 0 to 30 wt. % of at least one tackifying resin, based on the weight of the material (ii). Typically, the tackifier is present in an amount of up to 10 wt. % based on the weight of the material. The tackifying resin should be characterized as having a softening point between 70°C and 150°C and a viscosity at 150°C of less than 2000 Pa.s.

[0125] Exemplary tackifying resins that can be used alone or in combination in the present disclosure include aliphatic and alicyclic 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 and additional vinyl aromatic monomers; and gum rosin, gum rosin esters, wood rosin, wood rosin esters, tall oil rosin, tall oil rosin esters, and hydrogenated rosin esters.

[0126] Examples of commercially available tackifying resins useful in the present disclosure include Alcon™ P-70, P-90, P-100, P-125, P-115, M-90, M-100, M-110, M-120 hydrogenated C5 and / or C9 hydrocarbon feedstocks available from Arakawa Chemical; Eastotac® H-100, H-115, H-130 and H-142R available from Eastman Chemical Co.; Escorez® 5300, 5320, 5380, 5400, 5600, 5637 available from Exxon Chemical Co.; Foral 85 available from Pinova, Inc.; WING TACK® 95 and WING TACK® Extra available from Sartomer; and Regalite® 9001 and Regalite® 5100 available from Eastman Chemical Co.

[0127] Waxes constitute an optional component of the materials of the present disclosure. The hot melt materials of the present invention may contain iii) 0 to 20 wt. % wax, based on the weight of the material. If added, the material should contain 0.1 to 20 wt. %, e.g., 0.1 to 10 wt. % wax, based on the weight of the material. The wax is added to the hot melt material to reduce its melt viscosity. These waxes, which are solid at room temperature, can also be a determining factor in the adhesive's set-up time and softening point.

[0128] Without intending to limit the invention, waxes useful in the present invention should have a softening point of 50°C to 150°C and may include one or more of the following: 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.

[0129] To impart heat resistance, the wax of the material desirably comprises or consists of at least one functionalized polyolefin. The or each functionalized polyolefin contained in the material should preferably have a weight average molecular weight of from 2,000 to 20,000 daltons, for example from 2,500 to 15,000 daltons.

[0130] Representative olefin monomers that may be used alone or in combination to derive the functionalized polyolefin include, but are not limited to, ethylene, propylene, butylene, pentene, hexylene, heptene, and octene. Preferably, ethylene and / or propylene may be used.

[0131] 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, and crotonic acid; and the C1-C2 of crotonic acid. 18 Silicone (meth)acrylate monomers such as those taught and claimed in 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 available from 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.

[0132] Among the aforementioned monomers, 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 recommended, with maleic anhydride being the most preferred. Furthermore, good results have been obtained when the material contains at least one of the following components: maleated polyethylene, maleated polypropylene, or maleated poly(ethylene-co-propylene).

[0133] For the sake of completeness, exemplary commercially available maleated polyethylene and maleated polypropylene polymers that may find utility in the present invention include Eastman Chemical's EPOLENE E-43, G-3015, and G-3003, Honeywell's AC 575, AC 573, and DuPont's Fusabond E and Fusabond P.

[0134] Additional ingredients and additives in materials The pressure-sensitive adhesive materials of the present invention may, of course, also contain standard additives such as polar rubbers, pigments, fillers, rheology control agents, stabilizers, plasticizers, and leveling agents. The selection of suitable additives is limited only in that they must be compatible with the other material components and not detrimental to the use of the material.

[0135] The present disclosure does not preclude the presence of at least one polar rubber in the adhesive material, which is typically obtained by functionalizing a non-polar (co)polymer with a polar radical such as a nitrile, halogen, carboxyl, urethane, or ester group. Such functionalized rubbers include, but are not limited to, nitrile rubbers such as Vamac® available from DuPont, epoxidized natural rubber, hydroxylated natural rubber, carboxylated natural rubber, epoxidized synthetic rubber, hydroxylated synthetic rubber, carboxylated synthetic rubber, carboxylated nitrile rubber, carboxylated styrene-butadiene rubber, hydroxylated styrene-butadiene rubber, hydroxylated butadiene rubber, maleated styrene-isoprene-styrene block copolymer (SIS), maleated styrene-ethylene-butylene-styrene block copolymer (SEBS), (meth)acrylate-modified SEBS copolymer, sulfonated SEBS copolymer, maleated styrene-ethylene-propylene-styrene block copolymer (SEPS), (meth)acrylate-modified SEPS copolymer, and sulfonated SEPS copolymer.

[0136] The materials of the present disclosure may include electrically non-conductive fillers. Generally, there is no particular intention to limit the shape of the particles used as non-conductive fillers; acicular, spherical, ellipsoidal, cylindrical, bead-like, cubic, or plate-like particles may be used, alone or in combination. It is further contemplated that agglomerates of multiple particle types may be used. Similarly, there is no particular intention to limit the size of the particles used as non-conductive fillers. However, such non-conductive fillers typically have an average particle size (d50) measured by laser diffraction in the range of 0.1 to 1500 μm, e.g., 1 to 1000 μm or 1 to 500 μm.

[0137] Exemplary non-conductive fillers include, but are not limited to, calcium carbonate, calcium oxide, calcium hydroxide (lime powder), fused silica, amorphous silica, precipitated and / or pyrogenic silica, zeolite, bentonite, wollastonite, magnesium carbonate, silica earth, barium sulfate, alumina, clay, talc, titanium dioxide, iron oxide, zinc oxide, sand, quartz, flint, mica, glass beads, glass powder, and other ground mineral substances. Organic fillers can also be used, particularly wood fiber, wood flour, wood chips, cellulose, cotton, pulp, cotton, wood chips, shredded straw, rice husks, crushed walnut shells, and other shredded fibers. Short fibers such as glass fiber, glass filament, polyacrylonitrile, carbon fiber, Kevlar fiber, or polyethylene fiber can also be added.

[0138] Hollow spheres with mineral or plastic shells are also suitable as non-conductive fillers. These may be, for example, commercially available hollow glass spheres sold under the trademark Glass Bubbles®. Hollow spheres made of plastics, such as Expancel® or Dualite®, may also be used, and are described in EP 0 520 426 B1. They are composed of inorganic or organic materials and have a diameter of 1 mm or less, preferably 500 μm or less.

[0139] Non-conductive fillers that impart thixotropy to the material may be preferred in many applications. Such fillers are also described as rheological aids, for example, hydrogenated castor oil, fatty acid amides, or expandable plastics such as PVC.

[0140] It is also contemplated that the adhesive material may contain a conductive filler. Again, there is no particular intention to limit the shape of the particles used as the conductive filler, and acicular, spherical, ellipsoidal, cylindrical, bead-like, cubic, or plate-like particles may be used alone or in combination. It is further contemplated that agglomerates of multiple particle types may be used. Similarly, there is no particular intention to limit the size of the particles used as the conductive filler. However, such conductive fillers typically have an average volume particle size of 1 to 500 μm, e.g., 1 to 200 μm, as measured by laser diffraction / scattering.

[0141] Exemplary conductive fillers include, but are not limited to, silver, copper, gold, palladium, platinum, nickel, gold- or silver-coated nickel, carbon black, carbon fiber, graphite, aluminum, indium tin oxide, silver-coated copper, silver-coated aluminum, metal-coated glass spheres, metal-coated fillers, metal-coated polymers, silver-coated fibers, silver-coated spheres, antimony-doped tin oxide, conductive nanoparticles, nanosilver, nanoaluminum, nanocopper, nanonickel, carbon nanotubes, and mixtures thereof. The use of particulate silver and / or carbon black as the conductive filler is recommended.

[0142] The total amount of filler should not prevent the material from being easily applied to a substrate by the selected application method. Regardless, the materials of the present invention may typically contain 0 to 50 wt. % of filler, for example 0 to 30 wt. % of filler, based on the weight of the material.

[0143] For purposes of this invention, "stabilizer" should be understood as antioxidants, UV stabilizers, heat stabilizers, or hydrolysis stabilizers. When present, stabilizers may collectively account for up to 5% by weight, e.g., 0.1-2.5% by weight, based on the total weight of the material. Typical examples of stabilizers suitable for use in this invention include sterically hindered phenols, thioethers, benzotriazoles, benzophenones, benzoates, cyanoacrylates, acrylates, amines of the sterically hindered amine light stabilizer (HALS) type, phosphite compounds, sulfur-containing antioxidants such as thioethers and thiodipropionates, and mixtures thereof.

[0144] Sterically hindered phenols are well known to those skilled in the art and are characterized as phenolic compounds containing sterically bulky groups, such as tert-butyl groups, near their phenolic hydroxyl group. The presence of these groups near the hydroxyl group serves to delay its stretching frequency and correspondingly reduce its reactivity. Representative sterically hindered phenols include 1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-benzene; pentaerythritol tetrakis-3(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate; n-octadecyl-3(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate; 4,4'-methylenebis(2,6-tert-butyl-phenol); 4,4'-thiobis(6-tert-butyl-o-cresol); 2,6-di-tert-butylphenol; 6-(4-hydroxyphenoxy)-2,4-bis(n-octyl-thio)-1,3,5-triazine; di-n-octylthio)ethyl 3,5-di-tert-butyl-4-hydroxy-benzoate; and sorbitol hexa[3-(3,5-di-tert-butyl-4-hydroxy-phenyl)-propionate].

[0145] Exemplary commercially available stabilizers that can be used alone or in combination include SUMILIZER™ GM, SUMILIZER™ TPD, and SUMILIZER™ TPS manufactured by Sumitomo Chemical Co., Ltd.; IRGANOX™ 656, IRGANOX™ 1010, IRGANOX™ HP2225FF, IRGAFOS™ 168, IRGANOX™ 1076, IRGANOX™ 1520, IRGANOX™ 1726, and TINUVIN™ P manufactured by Ciba Specialty Chemicals; JF77™ manufactured by Johoku Chemical Co., Ltd.; TOMINOX™ TT manufactured by API Corporation; Cyanox™ LTDP available from Cytec Industries; Ethanox™ 330 available from Albemarle Corp.; and AO-412 S™ manufactured by ADEKA CORPORATION.

[0146] In some embodiments, a plasticizer may be included to adjust the softness and flexibility of the solidified adhesive material. In this case, one or more plasticizers may be selected from the group consisting of vegetable oils; mineral oils; soybean oils; aromatic esters such as dioctyl phthalate, diundecyl phthalate, tricresyl phosphate, and triisononyl mellitate; linear esters such as ditridecyl adipate; chlorinated paraffins; aromatic and naphthenic processing oils; alkylnaphthalenes; and low molecular weight polyisoprene, polybutadiene, or polybutylene resins. Typically, the amount of plasticizer should be 0 to 20 wt %, preferably 0 to 10 wt % or 0 to 5 wt %, based on the total weight of the material.

[0147] Methods and Applications The reactive hot melt adhesive material can be prepared by combining the components in predetermined amounts. The components can be mixed using any known mixing technique. However, it is preferred that the components are not mixed by hand, but rather are mixed mechanically, for example, using a static or dynamic mixer, in predetermined amounts under anhydrous conditions and without intentional exposure to light.

[0148] A first representative example of a mixing procedure involves adding all ingredients except the hybrid base copolymer to a jacketed mixing kettle equipped with a rotor, then raising the temperature of the mixture to a temperature above the softening point of the base polymer being added. Temperatures between 100°C and 160°C may be sufficient, although it will be understood that the exact temperature will depend on the softening and melting points of the specific ingredients. The polymer is then added to the kettle with stirring, and mixing continues until a uniform, homogeneous mixture is formed. Throughout the mixing process, the contents of the kettle may be protected with an inert gas such as carbon dioxide or nitrogen.

[0149] In a second exemplary mixing procedure, a resin or oil that is chemically compatible with the base copolymer is first added to the mixing kettle. The resin or oil is then melted or adjusted to obtain a liquid, and the base copolymer is then added stepwise and dissolved in the liquid. After the base copolymer is added, the remaining ingredients are added to the mixing kettle.

[0150] More typically, all ingredients of a material may be combined or homogeneously mixed in solid form. The resulting solids may then be added to a melting tank and heated to the required temperature for dispensing in the molten state. Again, the exact temperature of the melting tank will depend on the softening and melting points of the particular ingredients.

[0151] Generally, hot melt materials may be applied to substrates 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 spraying, air-assisted spraying, airless spraying, high-volume low-pressure spraying, slot spraying, and curtain spray coating. In this embodiment, when hot melt materials are used in potting operations, the material is typically introduced into a defined mold by static potting or centrifugal potting. In static potting techniques, the material is introduced into the potting mold while the mold is substantially stationary. In centrifugal potting, the potting material is introduced into the potting mold, and the mold is rotated, causing centrifugal force to force the potting material against the edge of the rotating mold. In either static or centrifugal potting, the introduction of the hot melt material may be accomplished by either a contact or non-contact method.

[0152] For coating, adhesive, and sealant applications, it is recommended that the material be applied at a wet film thickness of 10 μm to 250 μm, e.g., 25 μm to 150 μm. Alternatively, and not intended to be mutually exclusive with the above, it is recommended that the material be applied so that the coating weight of the material is 50 grams to 250 grams per square meter (gsm), preferably 50 grams to 150 grams.

[0153] In all of the above application methods, it is important that the hot melt material be sufficiently fluid to coat the substrate during application. Under certain circumstances, if the substrate is porous, the hot melt material may be fluid enough to penetrate the substrate. As such, the hot melt material should be characterized by a melt viscosity of up to 100,000 mPa·s measured at 130°C.

[0154] That being said, useful application temperatures are typically in the range of 100°C to 160°C, or 110°C to 150°C, with lower temperatures within this range being preferred as they may extend the working life of the curable material. The temperature of the material may be raised above the mixing temperature to the application temperature using conventional means, including microwave induction.

[0155] Immediately after application, the applied material is cured under light irradiation. The energy source used to promote the curing of the applied material emits at least one of ultraviolet (UV) radiation, infrared (IR) radiation, visible light, X-rays, gamma rays, or an electron beam (e-beam). After application, the material is typically activated in less than two minutes, typically between 0.1 and 100 seconds, e.g., between 0.1 and 10 seconds, when irradiated using a commercially available curing device. For completeness, it will be understood that activation of the material may be performed in an in-line process in which the coated substrate moves under a radiation-emitting curing device, and the aforementioned activation time refers to the exposure time of the applied material to irradiation in such an in-line process.

[0156] UV radiation should typically have a wavelength between 150 and 600 nm, preferably between 200 and 450 nm. Useful UV light sources include low-intensity fluorescent lamps, metal halide lamps, microwave-driven lamps, xenon lamps, UV-LED lamps, and laser beam sources such as excimer lasers and argon-ion lasers. The use of UV-LED lamps is recommended; mercury-based UV light systems are neither desirable nor necessary.

[0157] When e-beams are utilized to harden applied materials, the standard parameters for the operating equipment are accelerating voltages of 0.1-100 keV, 10-10 -3 The vacuum may be 0.0001 Pa, the electron current may be 0.0001 to 1 ampere, and the power may be 0.1 watts to 1 kilowatts.

[0158] The radiation dose required for sufficient curing of a particular material, for example to set a coating, depends on various factors, such as the angle of exposure to the radiation and the thickness of the applied material, but is generally between 100 and 10,000 mJ / cm 2 The typical curing absorption is thought to be 200-8000mJ / cm 2 The curing absorption amount is 300 to 6000 mJ / cm 2 can be considered to be very effective.

[0159] The reactive hot melt materials of the present invention may find utility, inter alia, in casting resins; potting and encapsulation resins; binders for fibers and / or particles; coatings of glass; coatings of mineral building materials such as lime and / or cement-bonded plaster, gypsum-containing surfaces, fiber cement building materials and concrete; coatings and sealings of wood and wood materials such as chipboard, fiberboard and paper; coatings of metal surfaces; and coatings and sealings of various plastic surfaces.

[0160] It is clear that hot melt materials can be used to bond a first substrate and a second substrate; typically, the material is applied between the two substrates and cured under light irradiation. Such bonding operations can be carried out using two main techniques: direct application of the hot melt material and application by transfer, which is described in more detail below. In a first embodiment, the hot melt material is applied to at least one surface (S) of the first substrate. 1 ), and at least one surface of the second substrate (S 2 ) and applied to the respective surfaces (S 1 ,S 2 ) contact the material so as to sandwich it. In another embodiment, the hot melt material may be applied to only one surface of the first substrate, and that surface is contacted with the second substrate.

[0161] First (S 1 ) and the second (S 2The substrates may be the same or different, but there are no particular limitations in either case. The substrates to be bonded may comprise or consist of, for example, ferrous metal materials such as iron, stainless steel, cold-rolled steel, and electrogalvanized steel; non-ferrous metal materials such as aluminum, zinc, and their alloys; silicon materials such as glass, monocrystalline silicon, polycrystalline silicon, amorphous silicon, or silicon oxide; industrial plastics; thermoplastic materials such as polyolefins, including polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), and acrylonitrile butadiene styrene (ABS); and carbon materials such as carbon fiber.

[0162] For the sake of 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. 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 be bonded together with any material disposed therebetween.

[0163] As described above, the first substrate and the second substrate (S 1 , S 2 ) may be bonded by a transfer method. This method includes (i) providing an article (A) comprising a curable film of a hot melt material, as defined above, disposed on a release liner and / or carrier substrate; (ii) transferring the curable film of the article to a substrate (S 1 , S 2 (iii) adhering to at least one of the substrates (S 1 , S 2 and (iv) curing the film between the substrates to adhere it to one another, wherein, if present, the release liner of article (A) is removed before and after step (ii).

[0164] An article (A) comprising a curable film of the hot melt material 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.

[0165] For the sake of completeness of this disclosure, and without intending to limit the disclosure, an exemplary article (A) will be described with reference to the accompanying drawings.

[0166] Figure 1 shows a single-sided tape (101) consisting of a carrier (102) and a curable film (103). The embodiment shown in Figure 2 can be a single-sided tape or label (201) consisting of a carrier (102) and a curable film (103), with the curable film (103) covered with a release liner (104) to protect the curable film and prevent unwanted adhesion.

[0167] Figures 3 and 4 show 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 onto a substrate. In FIG. 3, the transfer tape (301) consists of a release liner (104) coated with a curable film (103) of hot melt material. The release liner (104) should have release properties on both sides, but should not have equal release properties on both sides, so that when the transfer tape (301) is wound and unwound from a roll, there will be differences in the release effectiveness on the two sides of the release liner (104).

[0168] In Figure 4, the transfer tape (401) consists 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 removed independently of each other.

[0169] FIG. 5 shows a double-sided adhesive tape (501) comprising a carrier (102) having a first curable film (103) disposed on a first side of the carrier (102) and a second curable film (106) disposed 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, in that they may be derived from the same or different hot melt materials, with the proviso that at least one of the hot melt materials is provided in accordance with the present disclosure. A release liner (104) covers and protects the second curable film (106), and this liner (104) should have release properties on both sides, but not the same release properties on both sides. Under these circumstances, i.e., when winding and unwinding the transfer tape (501) from the roll, differences in release effectiveness will occur on both sides of the release liner (104).

[0170] A second embodiment of a double-sided adhesive tape (601) is shown in Figure 6. The depicted tape (601) consists of a carrier (102) with 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 in that they may be obtained from the same or different hot melt materials, with the proviso that at least one said hot melt material 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 relative to the curable films (103, 106).

[0171] In forming the aforementioned article (A), the hot melt material may be applied to a release liner and / or carrier and then cooled. Cooling can be accomplished, for example, by applying the hot melt material to a substrate carried by a coating roll having cooled water circulating therethrough. Alternatively, the hot melt material and the substrate, or a thermoplastic precursor of the substrate, can be coextruded as a laminate, after which the laminate is cooled and optionally stretched to induce partial orientation and crystallization.

[0172] Of course, manufacturing process parameters, including the specific materials used, their application thickness, and the operating conditions of the manufacturing equipment, can affect the degree of orientation and, consequently, the anisotropy, tack, and peel strength properties of the pressure-sensitive adhesive. For example, if the cooling rate is slow, the cooled pressure-sensitive adhesive may have high tack and an isotropic peel strength. If the cooling rate is accelerated, the tack of the pressure-sensitive adhesive may decrease and the peel strength may become more anisotropic. If the cooling rate is fast, the cooled pressure-sensitive adhesive may have very low pressure-sensitive tack and low or barely perceptible peel strength.

[0173] The following examples are illustrative of the present invention and are not intended to limit the scope of the invention in any way. [Example]

[0174] The following compounds were used in the examples: AIBN: Azobisisobutyronitrile, available from Sigma Aldrich VMOX: Vinylmethyloxazolidinone available from BASF SE DMAEA: Dimethylaminoethyl acrylate, available from Sigma Aldrich AA: Acrylic acid, available from Sigma Aldrich BA: Butyl acrylate, available from Sigma Aldrich 2-EHA: 2-ethylhexyl acrylate, available from Sigma Aldrich FA: Fumaric acid, available from Sigma Aldrich 2-PHpA: 2-propylheptyl acrylate, available from Sigma Aldrich Foral F85: Rosin-based tackifier, available from Pinova Inc.

[0175] i) Example of copolymer synthesis Seven copolymers were prepared by free radical polymerization according to the monomer compositions disclosed in Table 1 below.

[0176] [Table 1]

[0177] Polymerization was carried out in ethyl acetate solvent using 0.1 to 1 part by weight of AIBN as a free radical initiator. For copolymers 1 to 6 (CP1 to CP6), the polymerization was completed and the solvent was removed under reduced pressure at 130°C. For copolymer 7 (CP7), the polymerization was completed and Foral F85 tackifier was combined with the copolymer in an amount of 15% by weight based on the weight of the copolymer, and the solvent was removed from the resulting mixture under reduced pressure at 130°C. The product was designated HM7.

[0178] ii) Analytical testing The following analytical tests were performed on the hot melt materials described below. For completeness, peel strength tests, static shear tests, and shear adhesion failure tests (SAFT) were performed on various different coating weights (g / m 2 , gsm) and various different UV doses to cure the reactive hot melt material.

[0179] Viscosity: The viscosities shown below were measured at 120°C, 130°C, and 140°C using a Thermocel heated chamber and a Brookfield DVII viscometer, spindle 27, containing an 11g sample of material.

[0180] Coating and curing: Acrylic copolymers CP1-CP6 and material HM7 were preheated in an oven at 120°C. Using a lab coater with both rolls heated to 120-130°C, the materials were coated onto a 50 μm thick silicone release liner at a wet film thickness of 80 μm. The materials were then exposed to a UV-A LED (λ = 365 nm) at 1500 mJ / cm. 2 The resulting film was laminated with a 50 μm thick etched polyethylene terephthalate foil and conditioned at 23°C and 50% relative humidity for 24 hours. The appearance of the cured film was confirmed.

[0181] Peel strength: This parameter was measured according to International Organization for Standardization (ISO) standard 11339:2010-06 as follows. Standardized iron substrates (available from Rocholl) were used, pretreated by cleaning with acetone and ethyl acetate and dried for 30 minutes at room temperature and 50% relative humidity. Each adhesive member was cut into a 25 mm x 150 mm film and then laminated to the iron substrate by rolling a 2 kg roller back and forth for three strokes at a speed of 10 mm / s. The laminate was left for 20 minutes at room temperature and 50% relative humidity. The adhesive film was peeled from the surface of the substrate at a constant speed of 300 mm / min in a 180° direction. The force required for such peeling (peel force) was measured and recorded as bond strength (N / in).

[0182] Shear Adhesion Failure Test (SAFT): The thermal failure temperature of hot melt materials under shear was tested according to ASTM D4498 using a commercially available instrument, ES 07-II, from Elastocon. Each adhesive member was cut into a 25 mm x 25 mm film and then laminated to a standardized substrate using a 2 kg roller, rolling it back and forth twice at a speed of 10 mm / s. A 1 kg weight was attached to each member, and the temperature was increased from room temperature at a controlled rate (0.5 °C / min) until 200 °C was reached or the adhesive member failed.

[0183] The results of the above tests are shown in Table 2 below.

[0184] [Table 2]

[0185] In view of the foregoing description and examples, it will be apparent to those skilled in the art that equivalent modifications are possible without departing from the scope of the claims.

Claims

1. 1. A copolymer obtained by free radical polymerization, said copolymer comprising, based on the total weight of monomers: a) 0.1 to 10% by weight of a compound of formula (I): 【Chemistry 1】 [In the formula, R １ NH, CH ２ , S or O; R ２ ~R ９ are independently H, OH, SH, halide, CN, C １ -C ６ Alkyl, C １ -C ６ Alkoxy, C １ -C １２ Alkoxyalkyl, COOH, SR １０ , COOR １０ , N(R １０ ) ２ or N(R １０ ) ３ Q is selected from; Each R １０ is independently C １ -C ６ Alkyl or C ６ -C １８ aryl; and, Q is halide, acetate, phosphate, sulfate or nitrate. at least one copolymerizable photoinitiator represented by However, the group R ２ ~R ９ where j is one of the following: 【Chemistry 2】 A group selected from 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; and, Sp is the following type -[-{(X) ｋ -Y} ｌ -(X) ｍ -]- or -[--{(X) ｋ —Y} ｌ -(X) ｍ —Y} ｎ ]- [In the formula, 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 a C ２ -C １２ Alkylene, C ３ -C １８ Cycloalkylene, or C ６ -C １８ independently selected from arylene; and, Each Y is independently: 【Transformation 3】 is a divalent group selected from the group consisting of represents a spacer group of at least one copolymerizable photoinitiator, subject to the proviso that b) 90 to 99.9% by weight of at least one ethylenically unsaturated nonionic monomer that does not have epoxide groups or moieties that are decomposable under light irradiation to form radicals Copolymers obtained by free radical polymerization, comprising:

2. Based on total weight of monomers: 0.1 to 5% by weight, preferably 0.1 to 2% by weight, of a) said at least one copolymerizable photoinitiator of formula (I); and 95 to 99.9% by weight, preferably 98 to 99.9% by weight, of b) said at least one ethylenically unsaturated nonionic monomer having no epoxide groups or moieties that are decomposable under light irradiation to form radicals. The copolymer of claim 1 comprising:

3. R １ is NH, S or O.

4. R ２ ~R ９ are independently H, OH, C １ -C ４ Alkyl, C １ -C ４ Alkoxy, or C １ -C ８ The copolymer according to any one of claims 1 to 3, wherein the alkyl group is selected from alkoxyalkyl.

5. R ２ ~R ９ are independently H or C １ -C ４ The copolymer of claim 4, wherein the alkyl is selected from the group consisting of methyl, ...

6. Each R' is independently H, C １ -C ４ Alkyl or C ６ The copolymer according to any one of claims 1 to 5, wherein the aryl is selected from the group consisting of aryl.

7. 3. The copolymer of claim 1 or claim 2, wherein portion a) comprises at least one monomer selected from the group consisting of 9-oxo-3-(propan-2-yl)-9H-thioxanthen-2-ylpropen-2-oate and N-ethyl-N-[(9-oxo-9H-thioxanthen-3-yl)methyl]prop-2-enamide.

8. Based on the total weight of said part b): 80 to 99% by weight of bs) at least one ethylenically unsaturated monomer which, when homopolymerized, produces a homopolymer having a glass transition temperature (Tg) of less than 25°C; and 1 to 20% by weight of bh) at least one ethylenically unsaturated monomer which, when homopolymerized, produces a homopolymer having a glass transition temperature (Tg) greater than 25°C. The copolymer of any one of claims 1 to 7, comprising:

9. Based on the total weight of said part b): 80 to 99% by weight, preferably 85 to 99% by weight, and more preferably 85 to 95% by weight, of bs) at least one ethylenically unsaturated monomer which, when homopolymerized, produces a homopolymer having a glass transition temperature (Tg) of less than 20°C; and 1 to 20% by weight, preferably 1 to 15% by weight, more preferably 5 to 15% by weight of bh) at least one ethylenically unsaturated monomer which, when homopolymerized, produces a homopolymer having a glass transition temperature (Tg) greater than 30°C. The copolymer of claim 8 comprising:

10. 10. Copolymer according to any of claims 1 to 9, wherein part b) comprises 0.1 to 5 wt. %, preferably 0.1 to 2 wt. %, based on the total weight of the monomers, of b) iv) at least one tertiary amino(meth)acrylate.

11. 10. The copolymer according to any of claims 1 to 9, wherein part b) comprises 0.1 to 5 wt. %, preferably 0.1 to 2 wt. %, based on the total weight of the monomers, of b) iv) at least one monomer selected from the group consisting of N-vinylcaprolactam (NVC); vinylmethyloxazolidinone (VMOX); N-vinylformamide; N-vinylcarbazole; N-vinylacetamide; and N-vinylpyrrolidone.

12. A material crosslinkable under light irradiation, said material comprising or consisting of a copolymer as defined in any one of claims 1 to 11.

13. 1. A reactive hot melt composition crosslinkable under light irradiation, the composition comprising, by weight of the composition: 20 to 100% by weight of i) at least one copolymer as defined in any one of claims 1 to 11; 0 to 60 wt. % of ii) at least one tackifying resin; and 0-20% by weight of iii) wax 1. A reactive hot melt composition comprising:

14. A coating, adhesive or sealant obtained by crosslinking under light irradiation of a reactive hot melt material as defined in claim 13.

15. A hot melt pressure sensitive adhesive (HMPSA) obtainable by crosslinking under light irradiation of a reactive hot melt composition as defined in claim 13.

16. 14. An article (A) comprising a curable film of the hot melt composition defined in claim 13, wherein the film is disposed on a release liner and / or a carrier substrate.

17. 17. The article (A) of claim 16, which is a label, a single-sided tape, a transfer tape, or a double-sided tape.

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