Photolabile barbiturate compound
阅读说明：本技术 光不稳定的巴比妥酸酯化合物 (Photolabile barbiturate compound ) 是由 威廉·H·莫泽 埃里克·M·汤森 扎卡里·J·汤普森 玛丽·M·卡鲁索戴利 迈克尔·A·克罗 于 2019-01-16 设计创作，主要内容包括：本公开提供了一种用于引发聚合的氧化还原引发剂体系,所述氧化还原引发剂体系包含氧化剂、来源于巴比妥酸酯的光不稳定还原剂和参与氧化还原循环的过渡金属络合物。在暴露于光化辐射诸如UV时,光不稳定化合物光解,从而释放所述还原剂并引发氧化还原引发的聚合。(The present disclosure provides a redox initiator system for initiating polymerization comprising an oxidizing agent, a photolabile reducing agent derived from a barbiturate ester, and a transition metal complex participating in a redox cycle. Upon exposure to actinic radiation, such as UV, the photolabile compound photolyzes, releasing the reducing agent and initiating redox-initiated polymerization.)
1. A polymerizable composition comprising a polymerizable component and a redox initiation system comprising:
a) a transition metal complex participating in a redox cycle;
b) oxidizing agent
A photolabile reducing agent of the formula:
wherein
R1、R2And R3Each independently is H, C1-18A hydrocarbyl group; and is
a)RLight (es)Is a photolabile group.
2. The polymerizable composition of claim 1, wherein the photolabile group RLight (es)Selected from the group consisting of a phenacyl group, a 2-alkylphenacyl group, an ethylene-bridged phenacyl group, a p-hydroxybenzoylmethyl group, a benzoin group, an o-or p-nitrobenzyl group, an o-nitro-2-phenethyloxycarbonyl group, a coumarin-4-ylmethyl group, a benzyl group, an o-or p-hydroxybenzyl group, an o-or p-hydroxynaphthyl group, a2, 5-dihydroxybenzyl group, a 9-phenylthioxanthyl group, a 9-phenylxanthyl group, an anthraquinone-2-yl group, an 8-halobenzyl groupA-7-hydroxyquinolin-2-ylmethyl group and a pivaloyl glycol group.
3. The polymerizable composition of any one of the preceding claims, wherein the transition metal complex has the formula:
[MLp]n+A-wherein M is a transition metal participating in a redox cycle,
l is a ligand, a "is an anion, n is a formal charge on the transition metal of integer value 1 to 7, preferably 1 to 3, and p is the number of ligands on the transition metal of value 1 to 9, preferably 1 to 2.
4. The polymerizable composition of claim 3 wherein M is selected from the group consisting of Cu, Fe, Ru, Cr, Mo, Pd, Ni, Pt, Mn, Rh, Re, Co, V, Au, Nb, and Ag.
5. The polymerizable composition of claim 4 wherein M is selected from the group consisting of copper, iron, cobalt, and platinum.
6. The polymerizable composition of any one of the preceding claims, wherein the redox initiator system is present in the composition in an amount of from 0.05 parts by weight to about 10 parts by weight based on 100 parts by weight of the polymerizable component of the polymerizable composition.
7. The polymerizable composition of any one of the preceding claims, wherein the polymerizable composition further comprises a second reducing agent selected from tertiary amines; an aromatic sulfinate; thiourea; and mixtures thereof.
8. The polymerizable composition of any one of the preceding claims, wherein the oxidizing agent of the redox initiator system is selected from the group consisting of persulfuric acid and salts thereof; peroxides, hydroperoxides; transition metals, perboric acid and salts thereof, permanganic acid and salts thereof, perphosphoric acid and salts thereof, and mixtures thereof.
9. The polymerizable composition of any one of the preceding claims, comprising more than one oxidizing agent.
10. The polymerizable composition of any one of the preceding claims, wherein the polymerizable component comprises:
from 85 to 100 parts by weight of a (meth) acrylate;
0 to 15 parts by weight of an acid functional ethylenically unsaturated monomer;
iii.0 to 10 parts by weight of a non-acid functional ethylenically unsaturated polar monomer;
0 to 5 parts of a vinyl monomer; and
0 to 5 parts of a multifunctional (meth) acrylate;
from 0.1 to 10 parts by weight of the redox initiator system, based on 100 parts by weight of i) to v).
11. The polymerizable composition of claim 10, further comprising 0.01 to 5 parts of a multifunctional (meth) acrylate.
12. The polymerizable composition of any one of claims 1-11, further comprising an inorganic filler.
13. The polymerizable composition of any one of claims 1-9 comprising one or more polymerizable vinyl monomers and the redox initiator system.
14. The polymerizable composition of claim 13 wherein the vinyl monomer is selected from the group consisting of vinyl ethers, vinyl esters, styrene, substituted styrenes, vinyl halides, divinylbenzene, olefins, isoprene, butadiene, and mixtures thereof.
15. The polymerizable composition of any one of the preceding claims, wherein the molar ratio of the transition metal complex relative to the oxidizing agent is from 1:1000 to 1: 5.
16. The polymerizable composition of any one of the preceding claims, wherein the molar ratio of oxidizing agent to reducing agent is from 1:1.5 to 1.5: 1.
17. The polymerizable composition of any one of the preceding claims, wherein the oxidizing agent and reducing agent are present in an amount of 0.01 to 10 parts by weight, based on the total weight of the polymerizable components of the polymerizable composition.
18. The polymerizable composition of any one of claims 1-17, wherein the polymerizable component comprises:
i. up to 100 parts by weight of a (meth) acrylate;
from 0 to 15 parts by weight, preferably from 0.5 to 15 parts by weight, of an acid-functional ethylenically unsaturated monomer;
iii.0 to 15 parts by weight of a non-acid functional ethylenically unsaturated polar monomer;
0 to 5 parts of a vinyl monomer;
0 to 100 parts of a multifunctional (meth) acrylate, relative to 100 parts of i-iv; and
vii the redox initiator system (comprising the transition metal complex, an oxidizing agent and a photolabile reducing agent) in an amount of from about 0.1% to about 5.0% by weight relative to 100 parts of total monomers i-v.
19. The polymerizable composition of claim 18 comprising greater than 50 parts by weight of a multifunctional (meth) acrylate based on 100 parts by weight of i.
20. The polymerizable composition of any one of claims 1-18, further comprising 1 to 35 parts by weight of a toughening agent relative to 100 parts by weight of the polymerizable components of the polymerizable composition.
21. The polymerizable composition of any one of the preceding claims, wherein the transition metal complex is copper (II) naphthenate.
22. The polymerizable composition of any one of claims 1-21 wherein the polymerizable ethylenically unsaturated component comprises a reactive oligomer having pendant polymerizable groups.
23. The polymerizable composition of claim 22, wherein the reactive oligomer comprises:
a) greater than 50 parts by weight, preferably greater than 75 parts by weight, most preferably greater than 80 parts by weight of (meth) acrylate ester monomer units;
b)0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, most preferably 1 to 3 parts by weight of monomer units having a radically polymerizable side chain functional group,
c)0 to 20 parts by weight of other polar monomer units, wherein the sum of the monomer units is 100 parts by weight.
24. A method of polymerization, the method comprising combining a first mixture comprising a transition metal complex with a second mixture comprising an oxidizing agent and a photolabile reducing agent, polymerizable components in the first mixture and/or the second mixture, and irradiating the resulting combined mixture to photolyze the photolabile transition metal complex and initiate a redox polymerization cycle.
25. A photolabile reducing agent having the formula:
wherein
R1、R2And R3Is C1-18A hydrocarbyl group; and is
RLight (es)Is a photolabile group.
26. The photolabile reducing agent according to claim 25, wherein the photolabile group RLight (es)Selected from the group consisting of a phenacyl group, a 2-alkylphenacyl group, an ethylene-bridged phenacyl group, a p-hydroxybenzoylmethyl group, a benzoin group, an o-nitrobenzyl group, an o-nitro-2-phenethyloxycarbonyl group, a coumarin-4-ylmethyl group, a benzyl group, an o-hydroxybenzyl group, an o-hydroxynaphthyl group, a2, 5-dihydroxybenzyl group, a 9-phenylthioxanthyl group, a 9-phenylxanthyl group, an anthraquinone-2-yl group, an 8-halo-7-hydroxyquinolin-2-ylmethyl group, and a pivaloyl glycol group.
27. The photolabile reducing agent according to any one of claims 25 or 26, derived from the enolate of: 1,3, 5-trimethylbarbituric acid, 1,3, 5-triethylbarbituric acid, 1, 3-dimethyl-5-ethylbarbituric acid, 1, 5-dimethylbarbituric acid, 1-methyl-5-ethylbarbituric acid, 1-methyl-5-propylbarbituric acid, 5-ethylbarbituric acid, 5-propylbarbituric acid, 5-butylbarbituric acid, 1-benzyl-5-phenylbarbituric acid and l-cyclohexyl-5-ethylbarbituric acid.
28. A multilayer article comprising a coating of the polymerizable composition of any one of claims 1 to 22 on a substrate.
29. The multilayer article of claim 28 wherein the substrate is a release liner.
30. The multilayer article of claim 28 wherein the substrate is a tape backing.
31. The multilayer article of claim 30, wherein the polymerizable composition is disposed between two substrates.
32. The polymerizable composition of any one of claims 1-22, further comprising a film-forming polymer.
33. The polymerizable composition of any one of claims 1-22, wherein the polymerizable component comprises one or more ethylenically unsaturated polymerizable oligomers.
Background
Redox reactions represent an important method for initiating the cure of acrylates, methacrylates, and other vinyl-based resins, including adhesive formulations. Redox-initiated curing generally has advantages over photo-initiated curing, including improved depth of cure and slower stress buildup during the initial stages of curing.
The great challenge in using redox initiation systems is to find an optimal balance between stability and reactivity. The reactivity of the redox system needs to be high enough to fully cure and achieve mechanical properties in a short period of time. However, if the reactivity is too high, problems such as premature curing, stress accumulation, and poor storage stability of the formulation may be encountered.
Free radical polymerization of one or more vinyl compounds using certain β -dicarbonyl (i.e., 1, 3-dicarbonyl) compounds in the presence of peroxide and/or oxygen, a halide salt, and a copper compound, such as copper acetylacetonate, is described in U.S. patent 3,347,954(Bredereck et al). Such compositions cause free radical polymerization of one or more vinyl compounds over time, with shorter times generally being preferred. Because the composition is spontaneously reactive, it is common practice to provide it as a two-part system, such as, for example, part a and part B combined immediately prior to use.
Disclosure of Invention
Applicants have provided a method to overcome these problems by creating an "on-demand" redox-initiated cure, wherein the reducing agent of the redox cure initiator system has a latent activity upon storage and delivery of the formulation, which can then be triggered when needed.
The present disclosure provides a redox initiator system for initiating polymerization comprising an oxidizing agent, a photolabile reducing agent and a transition metal complex participating in a redox cycle. Upon exposure to actinic radiation, such as UV, the photolabile compound photolyzes, thereby generating a reducing agent and initiating redox-initiated polymerization. Advantageously, polymerization of the compositions of the present invention can be initiated by exposure to actinic radiation, but no continued irradiation is required. When the redox initiator system is combined with the polymerizable component monomers or oligomers to form a polymerizable composition, polymerization can be initiated and then molecular weight and physical properties built up as the composition continues to cure in the absence of light.
In some embodiments, the polymerizable compositions described herein combine the advantages of Pressure Sensitive Adhesives (PSAs) and structural adhesives in the form of a one-component light triggered PSA versus a (semi) structural acrylic adhesive. The adhesive functions as a conventional PSA in its uncured or partially cured state, providing ease of application, high wet-out and initial strength. Application of short UV light triggers initiation of a free radical generating redox reaction that proceeds after removal of light, resulting in a stable cure rate and a concomitant increase in cohesive strength. Finally, the curing will be smooth at a level sufficient to impart structural or semi-structural properties to the adhesive.
In many embodiments, this combination of properties and curing behavior will be particularly useful in the common case of a permanent bond between two opaque substrates. In the absence of UV trigger, the modulus of the adhesive is below the level specified by the Dahlquist criterion, which means that the material is tacky and it can only form a bond with the substrate under the application of pressure. Next, a UV trigger is applied to the exposed side of the adhesive, initiating a self-sustaining redox reaction, but leaving the surface tacky and capable of wetting a second substrate within a reasonable period of time ("open time"). After bonding is complete, the adhesive continues to cure until its modulus reaches a level sufficient to achieve structural strength.
In one aspect, the present disclosure provides a polymerizable composition comprising one or more ethylenically unsaturated polymerizable monomers or oligomers and an initiator system that participates in a reversible redox cycle upon irradiation.
In another aspect, the present disclosure provides a structured adhesive composition comprising a multifunctional (meth) acrylate monomer comprising two (preferably three) or more (meth) acrylate groups, and/or a multifunctional (meth) acrylate oligomer and optionally a (meth) acrylate functional diluent, and an initiator system that participates in a reversible redox cycle upon irradiation.
Detailed Description
The chemically polymerizable composition comprises a polymerizable component (e.g., an ethylenically unsaturated polymerizable monomer or oligomer) and a redox initiator system comprising a transition metal complex, an oxidizing agent, and a photolabile reducing agent of the formula:
wherein
R1、R2And R3Each independently is H, C1-18A hydrocarbyl group; and is
RLight (es)Is a photolabile group. Isomers Ia and Ib will be considered as functional equivalents.
R1、R2And R3May independently represent a hydrocarbyl group or a substituted hydrocarbyl group having 1 to 18 carbon atoms. Preferably, R1And R2Each having from 1 to 12 carbon atoms, more preferably from 1 to 8 carbon atoms, and even more preferably from 1 to 4 carbon atoms. Exemplary radicals R1And R2Including methyl, ethyl, isopropyl, n-propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, hexadecyl and octadecyl. In general, the nature of the substituents in the substituted hydrocarbyl group (which may be mono-or poly-substituted) is not particularly critical,except that substituents which hinder free radical polymerization should be used in small amounts or not at all. Exemplary substituted hydrocarbyl groups include hydroxyhydrocarbyl groups (e.g., hydroxyethyl and hydroxypropyl), alkoxyhydrocarbyl groups (e.g., methoxyethyl and methoxyethoxy), alkanoylhydrocarbyl groups (e.g., acetylethyl and benzoylethyl), haloalkyl groups (e.g., chloroethyl and dichloropropyl), and dialkylaminohydrocarbyl groups (e.g., dimethylaminopropyl and diethylaminoethyl).
Examples of suitable barbituric acid derivatives of formulae Ia and Ib include those derived from: 1,3, 5-trimethylbarbituric acid, 1,3, 5-triethylbarbituric acid, 1, 3-dimethyl-5-ethylbarbituric acid, 1, 5-dimethylbarbituric acid, 1-methyl-5-ethylbarbituric acid, 1-methyl-5-propylbarbituric acid, 5-ethylbarbituric acid, 5-propylbarbituric acid, 5-butylbarbituric acid, 1-benzyl-5-phenylbarbituric acid and l-cyclohexyl-5-ethylbarbituric acid.
Any known photolabile group (R) which can be irradiated and cleaved or fragmented to release the transition metal may be usedLight (es)). Reference may be made to Petr Klan et al, chemically and biologically optically removable protecting groups: reaction mechanism and Efficiency, chemical review, 2013, vol 113, pp 119-191 (Petr Klan et al, Photoremovable protecting groups in Chemistry and Biology: Reaction Mechanisms and efficiencies, Chemreviews,2013, Vol.113, pp.119-191) and Jacob Wirz et al, photo-removable protecting groups: reaction mechanism and application, photochemical and photobiological sciences, 2002, volume 1, page 441-458 (Jacob Wirz et al, Photoremovable Protecting Groups: Reaction Mechanisms and Applications, Photochem. Photobiol. Sci.,2002, Vol.1, pp. 441-458).
With reference to formula I, photolabile groups "R" may be usedLight (es)"includes, but is not limited to, a phenacyl group, a 2-alkylphenacyl group, an ethylene bridged phenacyl group, an o-or p-hydroxybenzoyl group, a benzoin group, an o-nitrobenzyl group, an o-nitro-2-phenethyloxycarbonyl group, a coumarin-4-ylmethyl group, a benzyl group, an o-hydroxybenzyl group, a substituted benzyl group,an o-hydroxynaphthyl group, a2, 5-dihydroxybenzyl group, a 9-phenylthioxanthyl group, a 9-phenylxanthyl group, an anthraquinone-2-yl group, an 8-halo-7-hydroxyquinolin-2-ylmethyl group, and a pivaloyl glycol group.
The photolabile compounds of formula I are generally prepared by methods known in the art for preparing enol ethers or esters of β -dicarbonyl compounds in some embodiments, β dicarbonyl compound may be treated with a base or acid, and the resulting enol/enolate is then treated with RLight (es)The groups are alkylated or esterified. The compounds of formulae Ia and Ib can be prepared by addition elimination of the corresponding halogenated compounds.
The redox initiation system comprises a transition metal complex that participates in a redox cycle. Useful transition metal compounds have the formula
[MLp]n+A-Wherein M is a transition metal participating in a redox cycle,
l is a ligand, a "is an anion, n is a formal charge on the transition metal of integer value 1 to 7, preferably 1 to 3, and p is the number of ligands on the transition metal of value 1 to 9, preferably 1 to 2.
Useful transition metals M include the catalytically active valence states of Cu, Fe, Ru, Cr, Mo, Pd, Ni, Pt, Mn, Rh, Re, Co, V, Au, Nb, and Ag. Preferred lower valence metals include Cu (II), Fe (II), Ru (II), and Co (II). Other valences of these same metals may be used and the active lower valences generated in situ.
Useful anions A-Including halogen, C1-C6Alkoxy group, NO3 2-、SO4 2-、PO4 3-、HPO4 2-、PF6Triflate, hexafluorophosphate, methanesulfonate, arylsulfonate, CN-Alkyl carboxylates and aryl carboxylates.
The ligand L is used to dissolve the transition metal salt in a suitable solvent and adjust the redox potential of the transition metal to achieve the appropriate reactivity and selectivity. The ligand can direct the metal complex through the desired one-electron atom transfer process, rather than a two-electron process, such as oxidative addition/reductive elimination. The ligands may also enhance the stability of the complex in the presence of different monomers and solvents or at different temperatures. Acidic monomers and monomers that strongly complex transition metals can still be efficiently polymerized by appropriate choice of ligands.
Useful ligands include those having one or more nitrogen, oxygen, phosphorus and/or sulfur atoms that can coordinate to the transition metal through a sigma bond; ligands containing two or more carbon atoms that can coordinate to the transition metal through pi bonds; and ligands that can coordinate to the transition metal through μ bonds or η bonds.
Useful ligands include those having one or more nitrogen, oxygen, phosphorus and/or sulfur atoms which can coordinate to the transition metal via a sigma bond, these ligands being provided by monodentate and polydentate compounds preferably containing up to about 30 carbon atoms and up to 10 heteroatoms selected from the group consisting of aluminum, boron, nitrogen, sulfur, non-peroxidic oxygen, phosphorus, arsenic, selenium, antimony and tellurium, wherein the polydentate compound is preferably complexed with the metal M after the addition of a metal atom after the loss of zero, one or two hydrogensn+Forming a 4-, 5-or 6-membered saturated or unsaturated ring. Examples of suitable monodentate compounds or groups are carbon monoxide, alcohols such as ethanol, butanol and phenol; pyridine, nitrosonium ion (i.e., NO)+) (ii) a Compounds of group 15 elements such as ammonia, phosphine, trimethylamine, trimethylphosphine, tributylphosphine, triphenylamine, triphenylphosphine, triphenylarsine, tributylphosphite; nitriles such as acetonitrile, benzonitrile; isonitriles such as phenyl isonitrile, butyl isonitrile; carbene groups such as ethoxymethyl carbene, dithiomethoxy carbene; alkylene groups such as methylene and ethylene.
Suitable multidentate compounds or groups include bipyridine, 1, 2-bis (diphenylphosphino) ethane, bis (diphenylphosphino) methane, polyamines such as ethylenediamine, propylenediamine, tetramethylethylenediamine, hexamethyltriaminoethylamine, diethylenetriamine, 1, 3-diisocyanopropane and hydrogentripyrazolylborate; hydroxycarboxylic acids such as glycolic acid, lactic acid, salicylic acid; polyhydric phenols such as catechol and 2,2' -dihydroxybiphenyl; hydroxyamines such as ethanolamine, propanolamine and 2-aminophenol; dithiocarbamates, such as diethyldithiocarbamate, dibenzyldithiocarbamate; xanthates such as ethyl xanthate, phenyl xanthate; dithiolenes such as bis (perfluoromethyl) -1, 2-dithiolene; aminocarboxylic acids such as alanine, glycine, and anthranilic acid; dicarboxylic acid diamines, such as oxamides, biurets; diketones such as 2, 4-pentanedione; hydroxy ketones such as 2-hydroxyacetophenone; alpha-hydroxyximes such as salicylaldoxime; ketoximes, such as benzil oxime; 1, 10-phenanthroline, porphyrins, cryptates and crown ethers, such as 18-crown-6 and glyoximes, such as dimethylglyoxime.
Other suitable ligands which can coordinate to the transition metal via a sigma bond are inorganic groups, such as, for example, F-、OH-、Cl-、Br-、I-And H-(ii) a And organic radicals such as, for example, CN-、SCN-Acetoxy, formyloxy, benzoyloxy and the like. The ligand may also be a polymer unit; amino groups such as in poly (ethyleneamines); phosphino groups in poly (4-vinylphenyldiphenylphosphine); carboxylic acid groups in poly (acrylic acid); and an isonitrile group in poly (4-vinylphenylisonitrile).
Useful ligands containing two or more carbon atoms that can coordinate to the transition metal through a pi bond are provided by any monomeric or polymeric compound having accessible unsaturated groups (i.e., olefinic-C ═ C-groups; acetylenic-C ≡ C-groups; or aromatic groups having accessible pi electrons), regardless of the overall molecular weight of the compound.
Exemplary pi-bonded ligands are linear and cyclic olefinic and acetylenic compounds having less than 100 carbon atoms (when monomeric), preferably less than 60 carbon atoms, and 0 to 10 heteroatoms selected from nitrogen, sulfur, non-peroxy oxygen, phosphorus, arsenic, selenium, boron, aluminum, antimony, tellurium, silicon, germanium, and tin, such ligands being those such as ethylene, acetylene, propylene, methylacetylene, α -butene, 2-butene, diacetylene, butadiene, 1, 2-dimethylacetylene, cyclobutene, pentene, cyclopentene, hexene, cyclohexene, 1-acetylene3-cyclohexadiene, cyclopentadiene, 1, 4-cyclohexadiene, cycloheptene, 1-octene, 4-octene, 3, 4-dimethyl-3-hexene and 1-decene η3-allyl, η3-pentenyl, norbornadiene, η5Cyclohexadienyl, cycloheptatriene, cyclooctatetraene, and substituted and unsubstituted carbocyclic and heterocyclic aromatic ligands having up to 25 rings and up to 100 carbon atoms and up to 10 heteroatoms selected from nitrogen, sulfur, non-peroxy oxygen, phosphorus, arsenic, selenium, boron, aluminum, antimony, tellurium, silicon, germanium and tin, such as, for example, η5Cyclopentadienyl, benzene, mesitylene, toluene, xylene, tetramethylbenzene, hexamethylbenzene, fluorene, naphthalene, anthracene, naphthalene, toluene,
Preferred ligands include unsubstituted and substituted pyridines and bipyridines, tertiary amines (including multidentate amines such as tetramethylethylenediamine and hexamethyltriaminoethylamine), acetonitrile, phosphites (such as (CH)3O)3P), 1, 10-phenanthroline, porphyrins, cryptates and crown ethers (such as 18-crown-6). Most preferred ligands are multidentate amines, bipyridines and phosphites. Useful ligands and ligand-metal complexes which can be used in the initiator system according to the invention are described in Matyjaszewski and Xia, chemical reviews, Vol.101, p.2921-2990,2001 (Matyjaszewski and Xia, chem.Rev., Vol.101, pp.2921-2990,2001).
The molar ratio of photolabile reducing agent (of formula I) to transition metal complex is generally effective to polymerize the one or more selected polymerizable components, but may be from 1000:1 to 5:1, preferably from 500:1 to 25:1, more preferably from 250:1 to 50:1, and most preferably from 200:1 to 75: 1. The oxidizing agent and the photolabile reducing agent of the redox initiator system are used in approximately equimolar amounts. Generally, the molar ratio of oxidizing agent to photolabile reducing agent is from 1:1.5 to 1.5:1, preferably from 1:1.1 to 1.1: 1.
Suitable oxidizing agents are also familiar to those skilled in the art and include, but are not limited to, persulfuric acid and its salts, such as sodium, potassium, ammonium, cesium and alkylammonium salts. Preferred oxidizing agents include peroxides such as benzoyl peroxide, hydroperoxides such as cumyl hydroperoxide, t-butyl hydroperoxide, and amyl hydroperoxide, and salts of transition metals such as cobalt (III) chloride and ferric chloride, cerium (IV) sulfate, perboric acid and its salts, permanganic acid and its salts, perphosphoric acid and its salts, and mixtures thereof.
The reducing agent and the oxidizing agent are present in amounts sufficient to allow for a sufficient radical reaction rate. This rate was evaluated by combining all the ingredients in the polymerizable composition, except for the optional filler, and observing whether a cured mass was obtained.
Preferably, the photolabile reducing agent is present in an amount of at least 0.01 parts by weight, and more preferably at least 0.1 parts by weight, based on the total weight of the monomer components of the polymerizable composition. Preferably, the reducing agent is present in an amount of no greater than 10 parts by weight, and more preferably no greater than 5 parts by weight, based on the total weight of the polymerizable components of the polymerizable composition.
Preferably, the oxidizing agent is present in an amount of at least 0.01 parts by weight, and more preferably at least 0.10 parts by weight, based on the total weight of the polymerizable components of the polymerizable composition. Preferably, the oxidizing agent is present in an amount of no greater than 10 parts by weight, and more preferably no greater than 5 parts by weight, based on the total weight of the polymerizable components of the polymerizable composition.
The curable composition optionally contains a quaternary ammonium halide that accelerates the rate of free radical polymerization. Suitable quaternary ammonium halides include those having four hydrocarbyl (e.g., alkyl, alkenyl, cycloalkyl, aralkyl, alkaryl, and/or aryl) groups. Preferably, the hydrocarbyl groups are independently selected from hydrocarbyl groups having 1 to 18 carbon atoms, more preferably 1 to 12 carbon atoms, and more preferably 1 to 4 carbon atoms. Examples of suitable hydrocarbyl groups include methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, hexadecyl and octadecyl, benzyl, phenyl, tolyl, cyclohexyl, and methylcyclohexyl. Exemplary suitable quaternary ammonium compounds include tetramethyl ammonium halide, tetraethyl ammonium halide, tetrapropyl ammonium halide, tetrabutyl ammonium halide, ethyltrimethyl ammonium halide, diethyldimethyl ammonium halide, trimethylbutyl ammonium halide, trioctylmethyl ammonium halide, and benzyltributyl ammonium halide. Any halide (e.g., F, Cl, Br, I) ion can be used in the quaternary ammonium halide, but preferably the halide is chloride or bromide.
The quaternary ammonium salt may be present in the curable composition in any amount, although other amounts may be used, preferably in an amount of 0.01 to 5 wt%, preferably 0.1 to 2 wt%, relative to 100 parts of polymerizable monomer.
The present disclosure also provides a polymerizable composition comprising a redox initiator system including a transition metal complex, an oxidizing agent, and a photolabile reducing agent, and at least one polymerizable component monomer such as vinyl monomers and (meth) acryloyl monomers including acrylates, amides, and acids to produce (meth) acrylate homopolymers and copolymers. The redox initiator system is present in the composition in an amount of from about 0.1 to about 10 parts by weight, preferably from 0.1 to 5 parts by weight, based on 100 parts by weight of the polymerizable components of the polymerizable composition.
In some embodiments, the polymerizable composition comprises a redox initiator system and one or more vinyl monomers. Vinyl monomers useful in the polymerizable composition include vinyl ethers (e.g., methyl vinyl ether, ethyl vinyl ether), vinyl esters (e.g., vinyl acetate and vinyl propionate), styrene, substituted styrenes (e.g., alpha-methyl styrene), vinyl halides, divinyl benzene, olefins (e.g., isomers of propylene, butene, pentene, hexene through dodecene, isoprene, butadiene), and mixtures thereof.
In some embodiments, the polymerizable composition comprises one or more (meth) acrylate monomers. The (meth) acrylate ester monomers useful in preparing the (meth) acrylate ester (co) polymers are monomeric (meth) acrylic acid esters of non-tertiary alcohols, wherein the alcohols contain from 1 to 14 carbon atoms, and preferably both contain from 4 to 12 carbon atoms.
Examples of monomers suitable for use as the (meth) acrylate monomer include esters of acrylic or methacrylic acid with non-tertiary alcohols such as ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 1-hexanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 2-ethyl-1-butanol, 3,5, 5-trimethyl-1-hexanol, 3-heptanol, 1-octanol, 2-octanol, isooctanol, 2-ethyl-1-hexanol, 1-decanol, 2-propylheptanol, 1-dodecanol, 1-tridecanol, 1-tetradecanol, citronellol, dihydrocitronellol, and the like. In some embodiments, the preferred (meth) acrylate ester monomer is the ester of (meth) acrylic acid with butanol or isooctanol, or a combination thereof, although combinations of two or more different (meth) acrylate ester monomers are also suitable. In some embodiments, the preferred (meth) acrylate ester monomer is the ester of (meth) acrylic acid with an alcohol derived from a renewable source, such as 2-octanol, citronellol, or dihydrocitronellol.
In some embodiments, it is desirable for the (meth) acrylate monomer to include a high glass transition (T)g) A monomer. These high TgHomopolymers of the monomers have a T of at least 25 ℃ and preferably at least 50 ℃g. Examples of suitable monomers that can be used in the present invention include, but are not limited to, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, n-butyl methacrylate,Octadecyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, benzyl methacrylate, 3,5 trimethylcyclohexyl acrylate, cyclohexyl acrylate, N-octylacrylamide, and propyl methacrylate, or a combination.
The (meth) acrylate ester monomer is present in an amount of up to 100 parts by weight, preferably from 85 parts by weight to 99.5 parts by weight, excluding the amount of multifunctional (meth) acrylate ester, based on 100 parts of total monomer content used to prepare the polymer. Preferably, the (meth) acrylate ester monomer is present in an amount of 90 to 95 parts by weight based on 100 parts of the total monomer content. When containing high TgWhen monomeric, the copolymer may contain up to 50 parts by weight, preferably up to 20 parts by weight of the (meth) acrylate ester monomer component.
The polymerizable composition may comprise an acid functional monomer, where the acid functional group may be the acid itself, such as a carboxylic acid, or a portion may be a salt thereof, such as an alkali metal carboxylate. Useful acid functional monomers include, but are not limited to, those selected from ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulfonic acids, ethylenically unsaturated phosphonic acids or phosphoric acids, and mixtures thereof. Examples of such compounds include those selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, citraconic acid, maleic acid, oleic acid, beta-carboxyethyl (meth) acrylate, 2-sulfoethyl methacrylate, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, vinyl phosphonic acid, and mixtures thereof.
Due to their availability, the acid functional monomers of the acid functional copolymers are generally selected from ethylenically unsaturated carboxylic acids, i.e. (meth) acrylic acid. When even stronger acids are desired, the acidic monomers include ethylenically unsaturated sulfonic acids and ethylenically unsaturated phosphonic acids. The acid functional monomer is generally used in an amount of 0.5 to 15 parts by weight, preferably 1 to 15 parts by weight, most preferably 5 to 10 parts by weight, based on 100 parts by weight of the total monomers.
The polymerizable composition may comprise a polar monomer. Polar monomers useful in preparing the copolymers have both a certain degree of oil and water solubility, which causes the polar monomers to distribute between the water and oil phases in the emulsion polymerization. As used herein, the term "polar monomer" does not include acid functional monomers.
Representative examples of suitable polar monomers include, but are not limited to, 2-hydroxyethyl (meth) acrylate; n-vinyl pyrrolidone; n-vinyl caprolactam; (ii) acrylamide; mono-or di-N-alkyl substituted acrylamides; t-butyl acrylamide; dimethylaminoethylacrylamide; n-octyl acrylamide; tetrahydrofurfuryl (meth) acrylate, poly (alkoxyalkyl) (meth) acrylates including 2- (2-ethoxyethoxy) ethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxyethoxyethyl (meth) acrylate, 2-methoxyethyl methacrylate, polyethylene glycol mono (meth) acrylate; alkyl vinyl ethers, including vinyl methyl ether; and mixtures thereof. Preferred polar monomers include those selected from the group consisting of tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and N-vinylpyrrolidone. The polar monomer may be present in an amount of 0 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the total monomers.
When preparing the acrylic copolymer, the polymerizable composition may further comprise a vinyl monomer. When used, vinyl monomers useful in the (meth) acrylate polymer include vinyl esters (e.g., vinyl acetate and vinyl propionate), styrene, substituted styrenes (e.g., alpha-methyl styrene), vinyl halides, divinylbenzene, and mixtures thereof. As used herein, vinyl monomers do not include acid functional monomers, acrylate monomers, and polar monomers. When preparing the acrylic copolymer, such vinyl monomers are generally used in an amount of 0 to 5 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the total monomers.
A multifunctional (meth) acrylate may be incorporated into the blend of polymerizable monomers. Examples of useful multifunctional (meth) acrylates include, but are not limited to, di (meth) acrylates, tri (meth) acrylates, and tetra (meth) acrylates, such as 1, 6-hexanediol di (meth) acrylate, poly (ethylene glycol) di (meth) acrylate, polybutadiene di (meth) acrylate, polyurethane di (meth) acrylate, and propoxylated glycerin tri (meth) acrylate, and mixtures thereof. The amount and type of multifunctional (meth) acrylate is tailored to the application of the adhesive composition, such as an adhesive or hardcoat.
Generally, the multifunctional (meth) acrylate is present in an amount of up to 100 parts, preferably 0.1 to 100 parts, based on 100 parts by weight of the remaining polymerizable monofunctional monomer. In some embodiments, the multifunctional (meth) acrylate is used in an amount of greater than 50 parts by weight, based on 100 parts by weight of the remaining polymerizable monomers. In some embodiments, the multifunctional (meth) acrylate may be present in an amount of 0.01 to 5 parts, preferably 0.05 to 1 part, and higher in the hardcoat based on 100 parts of total monomers of the polymerizable composition for adhesive applications.
In such embodiments, the acrylic copolymer can be prepared from a polymerizable composition comprising:
i. up to 100 parts by weight, preferably from 85 to 99.5 parts by weight, of a (meth) acrylate;
from 0 to 15 parts by weight, preferably from 0.5 to 15 parts by weight, of an acid-functional ethylenically unsaturated monomer;
iii.0 to 15 parts by weight of a non-acid functional ethylenically unsaturated polar monomer;
0 to 5 parts by weight of a vinyl monomer;
0 to 100 parts by weight, relative to i-iv, of a multifunctional (meth) acrylate, preferably 50 to 100 parts by weight;
and
vi a redox initiator system (including a complex, an oxidizing agent, and a photolabile reducing agent) in an amount of from about 0.1% to about 5.0% by weight relative to 100 parts of total monomers i-v.
The polymerizable composition may also comprise other additives. Examples of suitable additives include tackifiers (e.g., rosin esters, terpenes, phenols, and aliphatic synthetic hydrocarbon resins, aromatic synthetic hydrocarbonsA resin or a mixture of an aliphatic synthetic hydrocarbon resin and an aromatic synthetic hydrocarbon resin), a surfactant, a plasticizer (other than a physical blowing agent), a nucleating agent (e.g., talc, silica or TiO2) Pigments, dyes, reinforcing agents, solid fillers, stabilizers (e.g., UV stabilizers), and combinations thereof. The additives may be added in an amount sufficient to obtain the desired characteristics of the cured composition prepared. The desired characteristics are determined in large part by the intended application of the resulting polymeric article.
Adjuvants may optionally be added to the composition such as colorants, abrasive particles, antioxidant stabilizers, thermal degradation stabilizers, light stabilizers, conductive particles, adhesion promoters, leveling agents, film-forming polymers, thickeners, matting agents, inert fillers, binders, blowing agents, fungicides, bactericides, surfactants, plasticizers, rubber toughening agents, and other additives known to those skilled in the art. They may also be substantially unreactive, such as both inorganic and organic fillers. These adjuvants, if present, may be added in amounts effective to achieve their intended purpose.
In some embodiments, a toughening agent may be used. Tougheners useful in the present invention are polymeric compounds having both a rubber phase and a thermoplastic phase, such as: graft polymers having a polymerized diene rubber core and a polyacrylate, polymethacrylate shell; graft polymers having a polyacrylate rubber core and a polyacrylate or polymethacrylate shell; and elastomeric particles polymerized in situ in an epoxide derived from a free-radically polymerizable monomer and a copolymerizable polymeric stabilizer.
Examples of a first class of useful toughening agents include graft copolymers having a polymeric diene rubber backbone or core onto which is grafted a shell of an acrylate or methacrylate, a monovinyl aromatic hydrocarbon, or mixtures thereof, such as disclosed in U.S.3,496,250(Czerwinski), which is incorporated herein by reference. Preferred rubber backbones comprise polymerized butadiene, or a polymerized mixture of butadiene and styrene. Preferred shells comprising polymerized methacrylates are lower alkanesRadical (C)1-C4) Preferred monovinyl aromatic hydrocarbons are styrene, α -methylstyrene, vinyltoluene, vinylxylene, ethylvinylbenzene, isopropylstyrene, chlorostyrene, dichlorostyrene and ethylchlorostyrene it is important that the graft copolymer contains no functional groups which would poison the catalyst.
An example of a second class of useful toughening agents is acrylate core-shell graft copolymers where the core or backbone is a polyacrylate polymer having a glass transition temperature below about 0 ℃, such as polybutylacrylate or polyisooctyl polyacrylate, onto which is grafted a polymethacrylate polymer (shell) having a glass transition temperature above about 25 ℃, such as polymethylmethacrylate.
A third class of tougheners useful in the present invention include elastomeric particles having a glass transition temperature (T) of less than about 25 ℃ prior to mixing with the other components of the compositiong). These elastomer particles are polymerized from a free-radically polymerizable monomer and a copolymerizable polymeric stabilizer that is soluble in the resin. The free radically polymerizable monomers are ethylenically unsaturated monomers, or diisocyanates in combination with co-reactive difunctional hydrogen compounds such as diols, diamines, and alkanolamines.
Useful toughening agents include core/shell polymers such as methacrylate-butadiene-styrene (MBS) copolymers wherein the core is a crosslinked styrene/butadiene rubber and the shell is a polymethyl acrylate (e.g., ACRYLOID KM653 and KM680 from Rohm and Haas, Philadelphia, PA), those having a core comprising polybutadiene and a shell comprising poly (methyl methacrylate) (e.g., KANE ACE M511, M521, B11A, B22, B31, and M901, available from cenna Corporation of Houston, TX, PA), those having a core comprising polybutadiene, and a shell comprising poly (methyl methacrylate), and CLEARSTRENGTH C223, available from ATOFINA Corporation of Philadelphia, adarina, philelelphia, PA), those having a polysiloxane core and a polyacrylate shell (e.g., atrophaea CLEARSTRENGTH S, available from organo-kogaku, wakawa-kogawa, inc, and gmik-h, inc, available from cheney CLEARSTRENGTH S, inc, and gmik-k Corporation, germany, inc GENIOPERL P22 from Wacker Silicones, Munich, Germany), those having a polyacrylate core and a poly (methyl methacrylate) shell (e.g., PARALOID EXL2330 from Rohm and Haas and STAPHYLOID AC3355 and AC3395 from Takeda Chemical Company, Osaka, Japan), those having an MBS core and a poly (methyl methacrylate) shell (e.g., PARALOID EXL26 2691A, EXL2691 and EXL2655 from Rohm and Haas), and the like, as well as mixtures thereof. Preferred modifiers include the ACRYLOID and PARALOID modifiers listed above and the like, as well as mixtures thereof.
The toughening agent may be used in an amount equal to about 1 to 35 parts by weight, preferably about 3 to 25 parts by weight, relative to 100 parts by weight of the polymerizable component of the polymerizable composition. The toughening agent increases the strength of the composition after curing without reacting with components of the polymerizable composition or impeding curing.
In some embodiments, the polymerizable composition may include one or more film-forming polymers that are not free-radically polymerizable. The term "film-forming organic polymer" refers to an organic polymer that, upon drying, agglomerates uniformly. Film-forming polymers suitable for use in the composition are typically thermoplastic organic polymers.
Examples of suitable polymers include: polyesters, such as polyethylene terephthalate or polycaprolactone; copolyesters, such as polyethylene terephthalate isophthalate; polyamides, such as polyhexamethylene adipamide; vinyl polymers such as poly (vinyl acetate/methyl acrylate), poly (vinylidene chloride/vinyl acetate); polyolefins, such as polystyrene, and copolymers of styrene and one or more acrylates, such as, for example, poly (styrene-co-butyl acrylate); polydienes, such as poly (butadiene/styrene); acrylic polymers such as poly (methyl methacrylate-co-ethyl acrylate), poly (methacrylate-co-acrylic acid); polyurethanes, such as the reaction products of aliphatic, cycloaliphatic or aromatic diisocyanates with polyester diols or polyether diols; and cellulose derivatives, for example cellulose ethers such as ethyl cellulose and cellulose esters such as cellulose acetate/butyrate. Combinations of film-forming polymers may also be used. Methods and materials for preparing aqueous emulsions or latexes of such polymers are well known and many are widely available from commercial sources.
In some embodiments, the crosslinkable composition may comprise a filler. In some embodiments, the total amount of filler is at most 50 weight percent, preferably at most 30 weight percent, and more preferably at most 10 weight percent filler. The filler may be selected from one or more of a variety of materials as are known in the art, and includes organic and inorganic fillers. Inorganic filler particles include silica, submicron silica, zirconia, submicron zirconia, and non-glassy particles of the type described in U.S. Pat. No. 4,503,169 (Randklev).
The filler component includes nanoscale silica particles, nanoscale metal oxide particles, and combinations thereof. Nanofillers are also described in U.S.7,090,721(Craig et al), 7,090,722(Budd et al), 7,156,911(Kangas et al) and 7,649,029(Kolb et al).
In some embodiments, the filler may be surface modified. A variety of conventional methods that can be used to modify the surface of the nanoparticles include, for example, adding a surface modifying agent to the nanoparticles (e.g., in the form of a powder or a colloidal dispersion), and allowing the surface modifying agent to react with the nanoparticles. Other useful surface modification methods are described, for example, in U.S. Pat. No. 2,801,185(Iler), U.S. Pat. No. 4,522,958(Das et al), U.S. Pat. No. 6,586,483(Kolb et al), each of which is incorporated herein by reference.
The surface modifying group may be derived from a surface modifying agent. Illustratively, the surface modifying agent can be represented by the formula X-Y, wherein the X groups are capable of attaching to the surface of the particle (i.e., the silanol groups of the silica particles) and the Y groups are reactive or non-reactive functional groups. The non-functional groups do not react with other components of the system (e.g., the substrate). The non-reactive functional groups may be selected such that the particles are relatively more polar, relatively less polar, or relatively non-polar. In some embodiments, the non-reactive functional group "Y" is a hydrophilic group, such as an acid group (including carboxylate, sulfonate, and phosphonate), an ammonium group, or a poly (oxyethylene) group, or a hydroxyl group. In other embodiments, "Y" may be a reactive functional group, such as an ethylenically unsaturated polymerizable group, including vinyl, allyl, vinyloxy, allyloxy, and (meth) acryloyl groups, which may be free radically polymerized with a polymerizable resin or monomer.
Such optional surface modifiers can be used in amounts such that 0% to 100%, typically 1% to 90% (if present) of the surface functional groups (Si-OH groups) of the silica nanoparticles are functionalized. The number of functional groups is determined experimentally, where a large number of nanoparticles are reacted with an excess of surface modifying agent such that all available reactive sites are functionalized with surface modifying agent. The lower functionalization percentage limit can then be calculated from the results. Generally, the surface modifying agent is used in an amount sufficient to provide up to twice the equivalent weight of the surface modifying agent relative to the weight of the inorganic nanoparticles. When used, the weight ratio of surface modifying agent to inorganic nanoparticles is preferably from 2:1 to 1: 10. If surface modified silica nanoparticles are desired, it is preferred that the nanoparticles be modified prior to incorporation into the coating composition.
The polymerizable compositions of the present invention can also be used to prepare hardcoats and structural or semi-structural adhesives. The term "hardcoat" or "hardcoat layer" means a layer or coating on the outer surface of an object, where the layer or coating has been designed to at least protect the object from abrasion.
The present disclosure provides hardcoat compositions comprising a redox initiator system and a multifunctional (meth) acrylate monomer and/or a multifunctional (meth) acrylate oligomer comprising two (preferably three) or more (meth) acrylate groups, and optionally a (meth) acrylate functional diluent.
Useful multifunctional (meth) acrylate monomers include three or more (meth) acrylate groups. Multifunctional (meth) acrylate monomers are useful in the practice of the present invention because they add to the hardcoatThe abrasion resistance of the layer. Preferred multifunctional (meth) acrylate monomers containing three or more (meth) acrylate groups include trimethylolpropane tri (meth) acrylate (TMPTA), pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate (Sartomer 355), dipentaerythritol penta (meth) acrylate (Sartomer 399), dipentaerythritol hydroxypenta (meth) acrylate (DPHPA), glycerol propoxylate tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, and mixtures thereof. Another useful radiation curable component of the present invention is a composition having two or more (meth) acrylate groups and an average molecular weight (M)w) Multifunctional (meth) acrylate oligomers in the range of about 400 to 2000.
Useful multifunctional (meth) acrylate oligomers include polyester (meth) acrylates, urethane (meth) acrylates, and (meth) acrylated epoxy (meth) acrylates. (meth) acrylated epoxy (meth) acrylates and polyester (meth) acrylates are most preferred because they tend to have relatively low viscosity and thus allow for a more uniform layer to be applied by spin coating. Specifically, preferred multifunctional (meth) acrylate oligomers include those commercially available from UCB radiation curing company (UCB Radcure, inc., Smyrna, Georgia) of smyland, Georgia and sold under the trade name ebecryl (eb): eb40 (tetra functional acrylated polyester oligomer), ENO (polyester tetra functional (meth) acrylate oligomer), Eb81 (multifunctional (meth) acrylated polyester oligomer), Eb600 (bisphenol a epoxy di (meth) acrylate), Eb605 (bisphenol a epoxy di (meth) acrylate diluted with 25% tripropylene glycol di (meth) acrylate), Eb639 (phenolic polyester oligomer), Eb2047 (tri functional acrylated polyester oligomer), Eb3500 (di functional bisphenol a oligomer acrylate), Eb3604 (multifunctional polyester oligomer acrylate), Eb6602 (tri functional aromatic urethane acrylate oligomer), Eb8301 (hexafunctional aliphatic urethane acrylate), EbW2 (di functional aliphatic urethane acrylate oligomer), and mixtures thereof. Most preferred among these are Eb600, Eb605, Eb80, and Eb8 l.
Molecular weight can be controlled by the use of chain transfer agents and chain retarders, including mercaptans, disulfides, triethylsilane, carbon tetrabromide, carbon tetrachloride, alpha-methylstyrene, and others such as are known in the art.
In some embodiments, the multifunctional (meth) acrylate oligomer may include a reactive oligomer having pendant polymerizable groups, the reactive oligomer comprising:
a) greater than 50 parts by weight, preferably greater than 75 parts by weight, most preferably greater than 80 parts by weight of (meth) acrylate ester monomer units;
b)1 to 10 parts by weight, preferably 1 to 5 parts by weight, most preferably 1 to 3 parts by weight of a monomer unit having a radically polymerizable side chain functional group,
c)0 to 20 parts by weight of other polar monomer units, wherein the sum of the monomer units is 100 parts by weight.
The reactive oligomer may be represented by the formula:
-[Munsaturated polyester]o[MEsters]p[MPolarity]q-，II
Wherein
[MUnsaturated polyester]Represents monomer units having a free radically polymerizable side chain functionality, and subscript "o" is parts by weight thereof;
[Mesters]Represents (meth) acrylate monomer units, and subscript "p" represents parts by weight thereof; and is
[MPolarity]Represents polar monomer units and the subscript "q" represents parts by weight thereof.
The reactive oligomer (II) of the composition comprises one or more pendant groups comprising a free-radically polymerizable unsaturated group, the pendant group comprising a (meth) acryloyl group, a (meth) acryloyloxy group, a propargyl group, a vinyl group, an allyl group, an ethynyl group, and a (meth) acrylamide. Namely, a monomer unit [ MUnsaturated polyester]Containing such polymerizable groups.
An indirect method of introducing pendant polymerizable unsaturated groups into the oligomer is to include reactive functional groups in the monomer units of the precursor oligomer, which can also be functionalized with ethylenically unsaturated compounds having functional groups that co-react with the functional groups of the precursor oligomer.
Useful reactive functional groups include, but are not limited to, hydroxyl, amino, oxazolonyl, oxazolinyl, acetoacetyl, azlactone, carboxyl, isocyanate, epoxy, aziridinyl, acid halide, and cyclic anhydride groups. Preferred among these are carboxyl, hydroxyl, amino, azlactone and aziridinyl groups. These pendant reactive functional groups are reacted with an unsaturated compound that contains a functional group that is co-reactive with the reactive pendant functional groups. When the two functional groups react, oligomers with pendant unsaturation are produced. In some applications, it may be desirable to use less than a stoichiometric equivalent of the unsaturated compound containing the co-reactive functional groups such that some of the side chain functional groups on the one or more oligomers remain unreacted. Specifically, the reactive oligomer of formula III can be prepared from a polymer having the formula [ MFG]A precursor oligomer of (a) a monomer unit having a reactive functional group that can be functionalized to provide a reactive oligomer of formula II.
When an "indirect method" of introducing a radically polymerizable side chain functional group is used, useful reactive functional groups include hydroxyl, secondary amino, oxazolinyl, oxazolonyl, acetyl, acetonyl, carboxyl, isocyanato, epoxy, aziridinyl, acyl halide, vinyloxy, and cyclic anhydride groups. In the case where the side-chain reactive functional group is an isocyanato functional group, the co-reactive functional group preferably comprises a secondary amino group or a hydroxyl group. Where the side-chain reactive functional group includes a hydroxyl group, the co-reactive functional group preferably includes a carboxyl, ester, acid halide, isocyanate, epoxy, anhydride, azlactone, or oxazoline group. Where the side-chain reactive functional group comprises a carboxyl group, the co-reactive functional group preferably comprises a hydroxyl, amino, epoxy, isocyanate or oxazoline group. Most typically, the reaction occurs between a nucleophilic functional group and an electrophilic functional group.
Preferred ethylenically unsaturated compounds useful for functionalizing the precursor oligomer have the general formula:
wherein R is21Is hydrogen, C1To C4An alkyl group or a phenyl group, preferably hydrogen or a methyl group; r20Is a single bond or a divalent linking group which links the ethylenically unsaturated group to the co-reactive functional group "FG" and preferably contains up to 34, preferably up to 18, more preferably up to 10 carbon and optionally oxygen and nitrogen atoms, and when R is20When not a single bond, it is preferably selected from
-R22-or
Wherein R is22Is an alkylene group having 1 to 6 carbon atoms, a 5-or 6-membered cycloalkylene group having 5 to 10 carbon atoms, or an alkylene-oxyalkylene group wherein each alkylene contains 1 to 6 carbon atoms, or is a divalent aromatic group having 6 to 16 carbon atoms; and FG is a co-reactive functional group capable of reacting with the side chain reactive functional group of the oligomer for introducing a radical polymerizable functional group.
Representative examples of useful compounds of formula III having co-reactive functional groups include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2, 3-dihydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2- (2-hydroxyethoxy) ethyl (meth) acrylate; aminoalkyl (meth) acrylates such as 3-aminopropyl (meth) acrylate and 4-aminostyrene; oxazoline-based compounds such as 2-vinyl-1, 3-oxazoline-5-one, 2-vinyl-4, 4-dimethyl-1, 3-oxazoline-5-one, 2-isopropenyl-4, 4-dimethyl-1, 3-oxazoline-5-one and 2-propenyl-4, 4-dimethyl-1, 3-oxazoline-5-one; carboxy-substituted compounds such as (meth) acrylic acid and 4-carboxybenzyl (meth) acrylate; isocyanate-substituted compounds such as isocyanatoethyl (meth) acrylate and 4-isocyanatocyclohexyl (meth) acrylate; epoxy-substituted compounds such as glycidyl (meth) acrylate; aziridinyl substituted compounds such as N-acryloyl aziridine and 1- (2-propenyl) -aziridine; and acryloyl halides, such as (meth) acryloyl chloride.
The reactive oligomer may itself be redox polymerized, or may utilize a multifunctional acrylate such as hexanediol di (meth) acrylate. Reactive oligomers having pendant polymerizable groups can be prepared as described in US 7598298(Lewandowski et al), US 7342047(Lewandowski et al), and US7074839(Fansler et al), each of which is incorporated herein by reference.
The polymerizable reactive oligomer component may further comprise a diluent monomer. The (meth) acrylate-functional diluent, also referred to herein as a "reactive diluent," is a relatively low molecular weight mono-or di-functional non-aromatic (meth) acrylate monomer. These relatively low molecular weight reactive diluents advantageously have a relatively low viscosity, for example a viscosity of less than about 30 centipoise (cps) at 25 ℃. Difunctional non-aromatic (meth) acrylates are generally preferred over monofunctional non-aromatic (meth) acrylates because they allow for faster cure times. Preferred reactive diluents include 1, 6-hexanediol di (meth) acrylate (HDDA, from UCB radiation curing Inc. of Schlemna, Georgia), tripropylene glycol di (meth) acrylate, isobornyl (meth) acrylate (1130A, radiation curing Inc. (Radcure)), 2 (2-ethoxyethoxy) ethyl (meth) acrylate (sold under the trade name Sartomer 256, from Sartomer Company of Exston, Pennsylvania (SARTOMER Company, Inc., Exton, Pennsylvania)), n-vinylformamide (Sartomer 497), tetrahydrofurfuryl (meth) acrylate (Sartomer 285), polyethylene glycol di (meth) acrylate (Sartomer 344), tripropylene glycol di (meth) acrylate (radiation curing Inc.), dialkoxy di (meth) neopentyl glycol acrylate (Radcure), dialkoxy di (meth) acrylate, Polyethylene glycol di (meth) acrylates and mixtures thereof.
In some embodiments, the polymerizable composition can comprise, based on 100 parts by weight of the polymerizable components of the polymerizable composition:
20 to 80 parts by weight of a polyfunctional (meth) acrylate monomer and/or a polyfunctional (meth) acrylate-reactive oligomer,
0 to parts by weight of a (meth) acrylate diluent,
20 to 75% by weight of silica (as such, whether functionalized or not), and
about 0.1 wt% to about 5.0 wt% of a redox initiator system.
In some embodiments, the polymerizable composition provides a structural and semi-structural adhesive composition, wherein a partially cured composition may be disposed between two substrates (or adherends) and then fully cured to produce a structural or semi-structural bond between the substrates. "semi-structural adhesives" are those cured adhesives having a lap shear strength of at least about 0.5MPa, more preferably at least about 1.0MPa, and most preferably at least about 1.5 MPa. However, those cured adhesives having particularly high lap shear strength are known as structural adhesives. "structural adhesives" are those cured adhesives having a lap shear strength of at least about 3.5MPa, more preferably at least about 5MPa, and most preferably at least about 7 MPa.
In some embodiments, the present disclosure provides an adhesive composition comprising a redox initiator system and a) a first reactive oligomer comprising (meth) acrylate monomer units, hydroxyl functional monomer units, and monomer units having a polymerizable group; b) comprises C2-C4A second component of alkylene oxide repeat units and polymerizable end groups, and c) a diluent monomer component.
The first component reactive oligomer has the general formula:
～[Mesters]a-[MOH]b-[MPolarity]c-[MSilyl radical]e-[MPoly(s) are polymerized]d～，
Wherein
-[MEsters]-represents interpolymerized (meth) acrylate monomer units, and subscript a is greater than 50 parts by weight;
-[MOH]-represents interpolymerized (meth) acryloyl monomer units having pendant hydroxyl groups, wherein subscript b represents 0 to 20 parts by weight,
[Mpolarity]Represents optional polar monomer units, wherein subscript c ranges from 0 to 20 parts by weight, preferably from 1 to 10 parts by weight,
[Msilyl radical]Represents silyl functional monomer units, wherein subscript e ranges from 0 to 10 parts by weight, preferably from 1 to 5 parts by weight; and is
[MPoly(s) are polymerized]Represents monomer units comprising polymerizable group silane functional monomer units and subscript d represents 1 to 10 parts by weight. The sum of subscripts a through e is 100 parts by weight. The wavy symbol indicates a continuous polymer chain. Such reactive oligomers are further described in applicants' co-pending US 2015/0284601(Yurt et al, herein incorporated by reference) and WO 2014/078115(Behling et al). By functionalizing M as set forth in Yurt' 601OHPendant hydroxyl groups of monomers, with polymerizable groups (M)Poly(s) are polymerizedUnit) functionalizes the oligomer. The second component of the Yurt' 601 composition comprises C2-C4Alkylene oxide units and 1 to 3 terminal polymerizable groups, such as (meth) acrylate groups.
In some embodiments, the amount of silica (including silica modified with conventional surface modifiers and unmodified silica) is from 20 to 75 weight percent, preferably from 50 to 70 weight percent.
The filler component includes nanoscale silica particles, nanoscale metal oxide particles, and combinations thereof. Nanofillers are also described in U.S. patent 7,090,721(Craig et al), 7,090,722(Budd et al), 7,156,911(Kangas et al) and 7,649,029(Kolb et al).
The polymerization of the invention can be carried out in bulk or in a solvent. Solvents, preferably organic solvents, may be used to aid in the dissolution of the initiator and initiator system in the polymerizable monomers and as processing aids. Preferably, such solvents do not react with the components. It may be advantageous to prepare concentrated solutions of the transition metal complex in a small amount of solvent to simplify the preparation of the polymerizable composition.
Suitable solvents include ethers such as diethyl ether, ethyl propyl ether, dipropyl ether, methyl tert-butyl ether, di-tert-butyl ether, glyme (dimethoxyethane), diglyme; cyclic ethers such as tetrahydrofuran and dioxane; an alkane; cycloalkanes; aromatic hydrocarbon solvents such as benzene, toluene, o-xylene, m-xylene, p-xylene; a halogenated hydrocarbon solvent; acetonitrile; lactones such as butyrolactone and valerolactone; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; sulfones such as tetramethylene sulfone, 3-methylsulfolane, 2, 4-dimethylsulfolane, butadiene sulfone, methyl sulfone, ethyl sulfone, propyl sulfone, butyl sulfone, methyl vinyl sulfone, 2- (methylsulfonyl) ethanol and 2,2' -sulfonyldiethanol; sulfoxides such as dimethyl sulfoxide; cyclic carbonates such as propylene carbonate, ethylene carbonate, and vinylene carbonate; carboxylic acid esters, such as ethyl acetate, methoxyethanolTM(Methyl CellosolveTM) And methyl formate; and other solvents such as dichloromethane, nitromethane, acetonitrile, ethylene glycol sulfite, and 1, 2-dimethoxyethane (glyme), mixtures of such solvents, and supercritical solvents (such as CO2). The polymerization according to the invention can also be carried out according to known suspension, emulsion and precipitation polymerization methods.
Preferably, the one or more monomers and the components of the redox initiator system are selected such that the initiation rate is no less than 1000 times (preferably no less than 100 times) slower than the rate of propagation and/or transfer of the generated radical groups to the polymer radical. In this application, "propagating" refers to the reaction of a polymer radical with a monomer to form a polymer-monomer adduct radical.
The polymerization may be carried out at a temperature of-78 ℃ to 200 ℃, preferably 0 ℃ to 160 ℃, and most preferably 20 ℃ to 100 ℃. The reaction should be carried out for a time sufficient to convert at least 10% (preferably at least 50%, more preferably at least 75%, and most preferably at least 90%) of the monomer to polymer. In general, the reaction time for complete curing will be from a few minutes to 5 days, preferably from 30 minutes to 3 days, and most preferably from 1 hour to 24 hours.
Preferably, the polymerizable composition comprises a "two-part" system, wherein the transition metal complex is in the first mixture, and the oxidizing agent, the photolabile reducing agent, and any filler are typically in the first mixture. The polymerizable monomer may be part of the first mixture and/or the second mixture, and is preferably in the first mixture. The two parts are combined, optionally coated on a substrate, and the redox reaction is initiated by exposure to actinic radiation. In another embodiment, the polymerizable composition comprises a "two-part" system in which the transition metal complex, the photolabile reducing agent, and the polymerizable monomer component are in a first mixture, and the oxidizing agent is in a second mixture.
The polymerizable composition and redox initiator system can be combined and irradiated by activating UV radiation to cleave or break the photolabile transition metal complex, initiate redox cycling, and polymerize one or more polymerizable components. The UV light source may be of two types: 1) relatively low intensity light sources, such as backlights, provide typically 10mW/cm in the wavelength range of 280 to 400 nanometers2Or lower intensity (measured according to procedures approved by the National Institute of Standards and Technology, the United states National Institute of Standards and Technology), for example, using Electronic Instrumentation and Technology Inc. of Stirling, Va&Uvimap manufactured by Technology, Inc (Sterling, VA))TMUM 365L-S radiometer), and 2) a relatively high intensity light source such as a medium pressure mercury lamp, which provides typically greater than 10mW/cm2Preferably between 15mW/cm2And 450mW/cm2The strength of (d) in between. High intensity and short exposure in the case of complete or partial polymerization of polymerizable compositions using actinic radiationOpen time is preferred. For example, 600mW/cm can be used successfully2And an exposure time of about 1 second. The intensity can be about 0.1mW/cm2To about 150mW/cm2Preferably about 0.5mW/cm2To about 100mW/cm2And more preferably about 0.5mW/cm2To about 50mW/cm2Within the range of (1). UV LEDs, such as Clearstone UV LED lamps (Clearstone Technologies inc., Hopkins, MN)385nm) may also be used.
The above compositions are applied to a substrate using conventional coating techniques modified as appropriate to the particular substrate. For example, these compositions can be applied to a variety of solid substrates by methods such as roll coating, flow coating, dip coating, spin coating, spray coating, knife coating, and die coating. These various coating methods allow the composition to be placed on the substrate at variable thicknesses, allowing for a wider range of uses for the composition.
The polymerizable composition can be coated onto a variety of flexible and rigid substrates using conventional coating techniques to produce coated articles. A flexible substrate is defined herein as any material that is conventionally used as a tape backing or that may have any other flexible material. Examples include, but are not limited to, plastic films such as polypropylene, polyethylene, polyvinyl chloride, polyester (polyethylene terephthalate), polycarbonate, poly (methyl (meth) acrylate) (PMMA), cellulose acetate, cellulose triacetate, and ethyl cellulose. A foam backing may be used.
In some preferred embodiments, the substrate may be selected so as to be transparent to the UV radiation used to initiate the redox cycle. The coated article can then be initiated by the thickness of the transparent substrate.
In some embodiments, the substrate is a release liner to form an adhesive article that configures the substrate/adhesive layer/release liner or release liner/adhesive/release liner. The adhesive layer may be cured, uncured or partially cured. The release liner typically has a low affinity for the curable composition. Exemplary release liners can be made from paper (e.g., kraft paper) or other types of polymeric materials. Some release liners are coated with a release agent, such as an outer layer of a silicone-containing material or a fluorocarbon-containing material. The release coating may be applied by solvent or solvent-free methods.
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