RICH COMONOMERS

FIELD

[001] The invention relates to photo polymerized copolymers of a 1,1-dicarbonyl substituted-l-alkene and a comonomer having an electron rich double bond, the compositions used to form the copolymers as well as methods of forming them by free radical polymerization initiated by irradiation (e.g., electromagnetic or electron beam).

BACKGROUND

[002] Today radiation cure remains to be the most advanced technique that enables extremely rapid and almost instant cure, uses formulations with infinite pot life and near zero VOC, can provide the best spatial resolution, and usually has the lowest energy consumption and carbon footprint. This set of unique capabilities allowed radiation cure to expand into multiple applications such as coatings, inks, adhesives, sealants, composites, shape-memory materials, 3D printing, imaging, and others.

[003] Among the most commonly used materials in radiation curable formulations are acrylates and methacrylates, where acrylates cure the fastest and slower curing methacrylates are usually chosen for their better mechanical properties. Other functional groups have been used to address shortcomings of acrylic/acrylate systems. For example, epoxides and oxetanes have been used to cationic and dual cure acrylate/acrylic systems to achieve lowered shrinkage and improved adhesion. Thiols and alkenes have been used to foster living polymerization techniques as well as to combat oxygen inhibition (e.g., reduce surface tackiness) to realize various advanced material properties. However, despite enhancing the versatility of radiation cure of acrylic/acrylate systems these materials still suffer from disadvantages.

[004] Acrylates and thiols have strong odors and may present EH&S issues, methacrylates and epoxides cure slowly, and cationic cured systems are moisture sensitive. Monomeric acrylates and methacrylates usually don't cure fully and result in high migration while their oligomers generally have a viscosity that is too high for uses in applications such as inkjet printing or some 3D printing. Additionally, free radical polymerization of acrylates is challenging to control, which often results in weakening of the mechanical properties of the cured materials. [005] To address some of the inherent problems with the use of acrylates in UV cure methylene malonates have been considered as a possible solution (see e.g., WO2019/014528 and WO2018/219729). Methylene malonates are low odor compounds with relatively low viscosity comparable to acrylates. Methylene malonates can be UV and anionically cured, including a dual free radical-anionic cure, which can be used to control the cure shrinkage and improve adhesion. However, the speed of free radical cure of methylene malonates is relatively slow and cure with acrylates usually results in poor performance due to undercure.

[006] Consequently, there is a need for new low viscosity and low odor compositions that can rapidly cure with low sensitivity to ambient air and moisture while achieving desired thermomechanical performance, good adhesion and overall excellent application performance when fully cured. Thus, it is highly desired to provide new UV curable compositions that allow for rapid cure while avoiding one or more of the problems of prior art systems such as those described above.

SUMMARY

[007] It has been discovered that 1,1-dicarbonyl substituted alkenes ("monomer") such as malonates cure significantly faster when they are radiation cured in the presence of compounds with electron rich carbon-carbon double bonds ("comonomer").

[008] The first aspect of the invention is a curable composition comprised of a 1,1- dicarbonyl substituted alkene, and an unsaturated compound with an electron rich double bond ("comonomer") and a photoinitiator. It has been discovered that the use of a 1,1-dicarbonyl substituted alkene such as malonates with a comonomer having an electron rich radically polymerizable bond, the copolymer may polymerize at rate substantially faster than the free radical polymerization of the 1,1-dicarbonyl substituted alkene alone and to a sufficiently high conversion suitable for UV cure and photopolymerization applications.

[009] The rapid cure coupled with low odor of the UV curable compositions based on 1,1- dicarbonyl substituted alkene and electron rich alkenes allows for uses in such applications as additive manufacturing or 3D printing. The necessary versatility in desired thermomechanical properties for the printed objects can also be realized via the breadth of electron rich alkenes and methylene malonates readily available or produced. This allows for compositions of the present invention to obtain properties not readily available from either electron rich alkenes or 1,1- dicarbonyl substituted alkenes alone, while minimizing or eliminating odor or EH&S issues. A second aspect of the invention is a method of making a copolymer article comprising

(i) providing an initial layer of the curable composition of the first aspect of the invention,

(ii) polymerizing the initial layer by exposing the composition to electromagnetic radiation to polymerize the curable composition forming the copolymer article. The method may further comprise abutting further layers and sequentially curing them to form a layered article such as an additive manufactured article. The article, because of the discovery of accelerated polymerization realized with the electron rich comonomers using the monomers described herein, allows for additive manufactured articles having layers of differing composition (e.g., differing comonomers) yet allows for excellent adhesion between the layers. Likewise, the method allows even for compositional differences within any given layer within the article. The acceleration, without limiting or being bound by any theory is believed to be due to alternating polymerization where the relatively sterically hindered methylene malonate radical adds to an electron rich alkene that produces a more active radical with respect to the addition to the double bond of the 1,1-dicarbonyl substituted alkenes, which in turn increases the propagation rate and the overall rate of cure.

[0010] A third aspect of the invention is a copolymer article comprised of a photoinitiator and a radically polymerized copolymer of a 1,1-dicarbonyl substituted alkene monomer and a comonomer comprised of an electron rich double bond. The properties of the article may vary widely depending on the monomer/comonomer ratio and chemical composition allowing for articles that may vary from elastic to rigid as well as have a wide range of glass transition temperatures (Tg). As such, the curable compositions and articles made therefrom may be suitable for a myriad of applications such as coatings, adhesives, additive manufactured articles, molding resins, various printing inks including inkjet inks, dental applications (e.g., fillings, inserts and the like) and medical applications among others.

DESCRIPTION OF THE DRAWING

[0011 ] Figure l is a graph of the percent C=C double bond conversion of a curable composition of this invention and compositions not of this invention. Figure 2 is a graph of the percent C=C double bond conversion of a curable composition of this invention and compositions not of this invention.

Figure 3 is a graph of the percent C=C double bond conversion of a curable composition of this invention and compositions not of this invention.

Figure 4 is a graph of the percent C=C double bond conversion of a curable composition of this invention and compositions not of this invention.

Figure 5 is a graph of the percent C=C double bond conversion of a curable composition of this invention and compositions not of this invention.

Figure 6 is a graph of the percent C=C double bond conversion of a curable composition of this invention and compositions not of this invention.

DETAILED DESCRIPTION

[0012] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. The specific embodiments of the present disclosure as set forth are not intended to be exhaustive or limit the scope of the disclosure.

[0013] One or more as used herein means that at least one, or more than one, of the recited components may be used as disclosed. Nominal as used with respect to functionality means the theoretical functionality, generally this can be calculated from the stoichiometry of the ingredients used. Generally, the actual functionality is different due to imperfections in raw materials, incomplete conversion of the reactants and formation of by-products. Residual content of a component refers to the amount of the component present in free form or reacted with another material, such as an oligomer or a polymer. Typically, the residual content of a component can be calculated from the ingredients utilized to prepare the component or composition. Alternatively, it can be determined utilizing known analytical techniques.

The 1,1-dicarbonyl alkene

[0014] The 1,1-dicarbonyl alkene compounds are for convenience referred to as "1,1- dicarbonyl alkene monomers" or just "monomer" interchangeably. The 1,1-dicarbonyl alkene monomers are compounds wherein a central carbon atom is doubly bonded to another carbon atom to form an ethylene group. The central carbon atom is further bonded to two carbonyl groups. Each carbonyl group is bonded to a hydrocarbyl group through a direct bond or an oxygen atom. Where the hydrocarbyl group is bonded to the carbonyl group through a direct bond, a keto group is formed. Where the hydrocarbyl group is bonded to the carbonyl group through an oxygen atom, an ester group is formed. The 1,1-dicarbonyl alkene may have a structure as shown below in Formula I, where X ¹ and X ² are an oxygen atom or a direct bond, and where R1 and R2 are each hydrocarbyl groups that may be the same or different. Both X ¹ and X ² may be oxygen atoms, such as illustrated in Formula IIA, one of X ¹ and X ² may be an oxygen atom and the other may be a direct bond, such as shown in Formula MB, or both X ¹ and X ² are direct bonds, such as illustrated in Formula IIC. The 1,1-dicarbonyl alkene compounds used herein may have all ester groups (such as illustrated in Formula IIA), all keto groups (such as illustrated in Formula IIC) or a mixture thereof (such as illustrated in Formula MB). Compounds with all ester groups may be preferred in some applications due to the flexibility of synthesizing a variety of such compounds.

Formula IIC

[0015] Where the cured composition is a film, coating, or a sealant, the film or sealant adheres to one or more substrates for the life or most of the life of the structure containing the cured composition. As an indicator of this durability, the curable composition (e.g., adhesive, film, coating, or sealant) may exhibit excellent results during accelerated aging. Residual content of a component refers to the amount of the component present in free form or reacted with another material, such as a polymer. Typically, the residual content of a component can be calculated from the ingredients utilized to prepare the component or composition. Alternatively, it can be determined utilizing known analytical techniques.

[0016] Heteroatom means nitrogen, oxygen, sulfur and phosphorus, more preferred heteroatoms include nitrogen and oxygen. Hydrocarbyl as used herein refers to a group containing one or more carbon atom backbones and hydrogen atoms, which may optionally contain one or more heteroatoms. Where the hydrocarbyl group contains heteroatoms, the heteroatoms may form one or more functional groups well known to one skilled in the art. Hydrocarbyl groups may contain cycloaliphatic, aliphatic, aromatic or any combination of such segments. The aliphatic segments can be straight or branched. The aliphatic and cycloaliphatic segments may include one or more double and/or triple bonds. Included in hydrocarbyl groups are alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, alkaryl and aralkyl groups. Cycloaliphatic groups may contain both cyclic portions and noncyclic portions. Hydrocarbylene means a hydrocarbyl group or any of the described subsets having more than one valence, such as alkylene, alkenylene, alkynylene, arylene, cycloalkylene, cycloalkenylene, alkarylene and aralkylene. One or both hydrocarbyl groups may consist of one or more carbon atoms and one or more hydrogen atoms. As used herein percent by weight or parts by weight refer to, or are based on, the weight of the solution composition unless otherwise specified.

[0017] 1,1-dicarbonyl alkene compound means a compound having a carbon with a double bond attached thereto and which is further bonded to two carbon atoms of carbonyl groups. A preferred class of 1,1-dicarbonyl alkene compounds are the methylene malonates which refer to compounds as shown below:

The term "monofunctional" refers to 1,1-dicarbonyl alkene compounds or a methylene malonate having only one core formula. The term "difunctional" refers to 1,1-dicarbonyl alkene compounds or a methylene malonate having two core formulas bound through a hydrocarbyl linkage between one oxygen atom on each of two core formulas. The term "multifunctional" refers to 1,1- dicarbonyl alkene compounds or methylene malonates having more than one core formula which forms a chain through a hydrocarbyl linkage between one oxygen atom on each of two adjacent core formulas. [0018] The 1,1-dicarbonyl alkene monomer may be a 1,1-diester-l-alkene. As used herein, diester refers to any compound having two ester groups. A 1,1-diester-l-alkene is a compound that contains two ester groups and a double bond bonded to a single carbon atom referred to as the one carbon atom. Dihydrocarbyl dicarboxylates are diesters having a hydrocarbylene group between the ester groups wherein a double bond is not bonded to a carbon atom which is bonded to two carbonyl groups of the diester. The term "ketal" refers to a molecule having a ketal functionality--!. e., a molecule containing a carbon bonded to two -OR groups, where O is oxygen and R represents any alkyl group.

[0019] The hydrocarbyl groups (e.g., R ¹ and R ² ), each may comprise straight or branched chain alkyl, straight or branched chain alkyl alkenyl, straight or branched chain alkynyl, cycloalkyl, alkyl substituted cycloalkyl, aryl, aralkyl, or alkaryl. The hydrocarbyl group may optionally include one or more heteroatoms in the backbone of the hydrocarbyl group. The hydrocarbyl group may be substituted with a substituent that does not negatively impact the ultimate function of the monomer or the polymer prepared from the monomer. Preferred substituents include alkyl, halo, alkoxy, alkylthio, hydroxyl, nitro, cyano, azido, carboxy, acyloxy, and sulfonyl groups. More preferred substituents include alkyl, halogen, alkoxy, allylthio, and hydroxyl groups. Most preferred substituents include halogen, alkyl, and alkoxy groups.

[0020] As used herein, alkaryl means an alkyl group with an aryl group bonded thereto. As used herein, aralkyl means an aryl group with an alkyl group bonded thereto and include alkylene bridged aryl groups such as diphenyl methyl groups or diphenyl propyl groups. As used herein, an aryl group may include one or more aromatic rings. Cycloalkyl groups include groups containing one or more rings, optionally including bridged rings. As used herein, alkyl substituted cycloalkyl means a cycloalkyl group having one or more alkyl groups bonded to the cycloalkyl ring.

[0021] The hydrocarbyl groups may include 1 to 30 carbon atoms, 1 to 20 carbon atoms, or 1 to 12 carbon atoms. Hydrocarbyl groups with heteroatoms in the backbone may be alkyl ethers having one or more alkyl ether groups or one or more alkylene oxy groups. Alkyl ether groups may be ethoxy, propoxy, and butoxy. Such compounds may contain from about 1 to about 100 alkylene oxy groups, about 1 to about 40 alkylene oxy groups, about 1 to about 12 alkylene oxy groups, or about 1 to about 6 alkylene oxy groups.

[0022] One or more of the hydrocarbyl groups (e.g., R ¹ , R ² , or both) may include a Ci-15 straight or branched chain alkyl, a Ci-15 straight or branched chain alkenyl, a C5-18 cycloalkyl, a Ce-24 alkyl substituted cycloalkyl, a C4-18 aryl, a C4-20 aralkyl, or a C4-20 aralkyl. The hydrocarbyl group may include a Ci-s straight or branched chain alkyl, a C _5-12 cycloalkyl, a Ce-u alkyl substituted cycloalkyl, a C _4-18 aryl, a C _4-20 aralkyl, or a C _4-20 aralkyl.

[0023] Alkyl groups may include methyl, propyl, isopropyl, butyl, tertiary butyl, hexyl, ethyl pentyl, and hexyl groups. More preferred alkyl groups include methyl and ethyl. Cycloalkyl groups may include cyclohexyl and fenchyl. Alkyl substituted groups may include menthyl and isobornyl, norbornyl as well as any other bicyclic, tricyclic or polycyclic structure.

[0024] Hydrocarbyl groups attached to the carbonyl group may include methyl, ethyl, propyl, isopropyl, butyl, tertiary, pentyl, hexyl, octyl, fenchyl, menthyl, and isobornyl, cyclic, bicyclic or a tricyclic group such as cyclohexyl, norbornyl, or tricyclodecanyl.

[0025] Monomers may include methyl propyl methylene malonate, dihexyl methylene malonate, di-isopropyl methylene malonate, butyl methyl methylene malonate, ethoxyethyl ethyl methylene malonate, methoxyethyl methyl methylene malonate, hexyl methyl methylene malonate, dipentyl methylene malonate, ethyl pentyl methylene malonate, methyl pentyl methylene malonate, ethyl ethylmethoxy methylene malonate, ethoxyethyl methyl methylene malonate, butyl ethyl methylene malonate, dibutyl methylene malonate, diethyl methylene malonate (DEMM), diethoxy ethyl methylene malonate, dimethyl methylene malonate, di-N- propyl methylene malonate, ethyl hexyl methylene malonate, methyl fenchyl methylene malonate, ethyl fenchyl methylene malonate, 2 phenylpropyl ethyl methylene malonate, 3 phenylpropyl ethyl methylene malonate, ethyl cyclohexyl methylene malonate, and dimethoxy ethyl methylene malonate.

[0026] Some or all of the 1,1-dicarbonyl alkene can also be multifunctional, having more than one core unit and thus more than one alkene group. Exemplary multifunctional 1,1-dicarbonyl alkenes are illustrated by the formula: wherein R ¹ and R ² are as previously defined; X is, separately in each occurrence, an oxygen atom or a direct bond; n is an integer of 1 or greater to any useful amount such as a polymer of 1,000 or 10,000 Daltons or more and R is a hydrocarbyl group, and the 1,1-dicarbonyl alkene has n + 1 alkenes. In the formula, n may be 1 to about 7, 1 to about 3, or 1. In exemplary embodiments R ² may be, separately in each occurrence, straight or branched chain alkyl, straight or branched chain alkenyl, straight or branched chain alkynyl, cycloalkyl, alkyl substituted cycloalkyl, aryl, aralkyl, or alkaryl, wherein the hydrocarbyl groups may contain one or more heteroatoms in the backbone of the hydrocarbyl group and may be substituted with a substituent that does not negatively impact the ultimate function of the compounds or polymers prepared from the compounds. Exemplary substituents may be those disclosed as useful with respect to R ¹ . In certain embodiments R ² may be, separately in each occurrence, Ci-15 straight or branched chain alkyl, C2-15 straight or branched chain alkenyl, C5-18 cycloalkyl, C&-2 alkyl substituted cycloalkyl, C4-18 aryl, C4-20 aralkyl or C4-20 aralkyl groups. In certain embodiments R ² may be separately in each occurrence Ci- ₈ straight or branched chain alkyl, C5-12 cycloalkyl, C6-12 alkyl substituted cycloalkyl, C4-18 aryl, C4-20 aralkyl or C4-20 alkaryl groups.

[0027] The 1,1-dicarbonyl substituted alkenes monomer desirably exhibit a sufficiently high purity so that it can be polymerized without impeding photoinitiated radical polymerization described herein. The purity of the 1,1-dicarbonyl substituted alkenes generally should be 60 mole percent or more, preferably 80 mole percent or more, more preferably 90 mole percent or more, even more preferably 95 mole percent or more, and most preferably 99 mole percent or more of the 1,1-dicarbonyl substituted alkenes is converted to polymer during the co-polymerization with the electron rich comonomer. The purity of the 1,1-dicarbonyl substituted alkenes is about 96 mole percent or greater, about 97 mole percent or greater, about 98 mole percent or greater, about 99 mole percent or greater, or about 99.5 mole percent or greater, based on the total weight of the 1,1-dicarbonyl substituted ethylene monomers.

[0028] The total concentration of any impurity having the alkene group replaced by an analogous hydroxyalkyl group (e.g., by a Michael addition of the alkene with water) may be dependent on whether the malonate is a monomer or oligomer. For example, the oligomer may have greater concentration of impurity so long as one or more alkenes remain in the oligomer. Generally, it may be desirable that 10 mole percent or less, more preferably about 5 mole percent or less, even more preferably about 1 mole percent or less, and most preferably about 0.5 mole percent or less, based on the total moles in the 1,1-dicarbonyl substituted alkenes. [0029] The 1,1-dicarbonyl alkene monomers may be produced and purified by the methods described in U.S. Pat. Nos. 8,609,8985; 8,884,051; 9,108,914 and 9,518,001 and Int. Pub. WO 2017/197212. Examples of such monomers are available under the tradenames CHEMILIAN and FORZA and include, for example, methylene malonate, dihexyl methylene malonate, dicyclohexyl methylene malonate and multifunctional polyester methylene malonates available from Sirrus, Inc., Loveland, OH.

The electron rich double bond containing compound

[0030] The curable composition is comprised of a compound having an electron rich carbon- carbon double bond (alkene) also referred to herein as "electron rich comonomer or comonomer". It is understood that the comonomer may have more than one electron rich double bond and may be in the form of an oligomer or polymer. The polymer may be a liquid or dissolved in a solvent and in a particular embodiment the polymer may be dissolved in a monomer or oligomer of the curable composition. The comonomer may also be comprised of other alkene bonds that are not electron rich (e.g an acrylate or methacrylate and referred to herein as "electron poor C=C compounds") so long as there is at least one electron rich carbon-carbon double bond. Examples of such compounds include 2-(2-Vinyloxyethoxy)ethyl acrylate (VEEA) and 2-(2-Vinyloxyethoxy)ethyl methacrylate.

[0031] In general, the electron rich double bond is one that is connected to an electron donating group that causes the double bond to be more electron rich than the methylene of the 1,1-dicarbonyl alkene. Illustratively, the carbon-carbon double bond is connected to a heteroatom such as an oxygen, nitrogen or sulfur (e.g., the oxygen of the ester is bonded to the carbon-carbon double bond). Illustratively the electron rich double bond is connected to a group such as an amine, alcohol, ether, amide, silane, ester, halide, alkyl, aryl or alkenyl. Such substituents may be of any size so long as they are not so large that they negatively impact the radiation induced cure such as described for the hydrocarbyl group (e.g., R ¹ and R ² ) above. Even though the halide group or phenyl group are not generally characterized as electron donating, the effect of such group on the 1,1-dicarbonyl alkene photoinitiation rate is also enhanced. The carbons of the electron rich double bond may be further substituted with the aforementioned groups or be unsubstituted with the alkene desirably being a vinyl or vinylidene. The carbons of the electron rich double bond may be further substituted with a hydrocarbyl group such as described above for R ¹ and R ² of the 1,1-dicarbonyl alkene so long as these substituents do not impact ability of the comonomer to accelerate the radiation induced cure rate of the 1,1- dicarbonyl alkene.

[0032] In one embodiment, the electron rich compound may be any that does not undergo appreciable free radical homopolymerization under like photoinitiation in the absence of the 1,1- dicarbonyl alkene compound or the rate of homopolymerization is slower than the 1,1-dicarbonyl alkene rendering it impractical for applications such as additive manufacturing. Illustratively, the rate of radical homopolymerization of the comonomer is at least about the same or slower than the 1,1-dicarbonyl alkene, 2 times slower, 4 times slower or even 10 times slower to essentially no homopolymerization. The rate generally is determined between 5% to 10% by mole of the carbon-carbon double bonds subject to radiation cure. The homopolymerization rate may be determined by any suitable method and, in particular, as described in the Examples.

[0033] In another embodiment, the electron rich compound may be one that undergoes radiation induced homopolymerization (curing) under like photoinitiation that is faster than the 1,1-dicarbonyl alkene. Illustratively, the rate may be 1.1 times, 1.5 times, 2 times, 4 times or even 10 times faster.

[0034] When copolymerizing the 1,1-dicarbonyl alkene such as a malonate and the electron rich double bond compound, the radiation induced cure rate is substantially increased compared to the homopolymerization (homo radiation induced curing) of the 1,1-dicarbonyl alkene. Illustratively, the rate may be 1.1 times, 1.5 times, 2 times, 4 times or even 10 to 20 times faster. This is the case even when the homopolymerization of the electron rich double bond compound's radiation induced cure rate is slower than that of the 1,1-dicarbonyl alkene alone or in essence does not occur.

[0035] Generally, the conversion of the monomer and comonomer double bonds that are subject to the radiation induced cure is an amount that makes a useful polymer within 10 minutes of initiation. Typically, this means that about 50% of the double bonds have been converted in the monomer and comonomer, but desirably at least 60%, 70% or even 80% of the double bonds have been converted in 10 minutes from photoinitiation. It is, however, understood that when there are multiple double bonds that may be reactive in either or both of the monomer or comonomer a useful polymer may be formed with lower amounts of double bond conversion, which is readily determinable by an ordinary skilled artisan.

[0036] Exemplary electron rich double bond compounds may include, vinyl ethers, vinyl aromatics, vinyl heteroaromatics, vinyl amides, vinyl lactones, vinyl lactams, vinyl carbonates, vinyl halides, vinyl amides, vinyl esters, olefins (e.g., alpha olefins) , cycloalkenes, allyl group containing compounds, vinyl silanes, vinyl sulfides, or any combination thereof.

[0037] Examples of vinyl ethers that may be suitable include but are not limited to those described in U.S. Pat. No. 5,045,572, U.S. Pat. No. 5,082,874, U.S. Pat. No. 4,864,054, U.S. Pat. No. 2,836,603, U.S. Pat. No. 5,989,627 and U.S. Pat. No. 5,672,675, U.S. Pat. No. 5,070,117 and UK Application No. 2,073,760 incorporated hereby reference. Sulfides having analogous structures to the ethers may also be used, which may be produced by known methods such as describe in US. Pat. No. 3,062,892 incorporated herein by reference. Illustrative examples include triethylene glycol divinyl ether (TEGDVE), 4-Hydroxybutyl vinyl ether (HBVE), diethyleneglycol divinyl ether (DVE-2), cyclohexane dimethanol monovinyl ether, and cyclohexane dimethanol divinyl ether as well as well as vinyl ether oligomers such as a urethane vinyl ether and polyester vinyl ether. [0038] Examples of vinyl aromatics include styrene and other substituted styrenic monomers such as vinylidene substituted aromatic monomers. Vinylidene substituted aromatic monomers comprise vinylidene, alkenyl groups, bonded directly to aromatic structures. The vinylidene substituted aromatic monomers may contain one or more aromatic rings, may contain one or two aromatic rings, or may contain one aromatic ring. The aromatic rings can be unsubstituted or substituted with a substituent that does not interfere with polymerization of the vinylidene substituted aromatic monomers, or the fabrication of the polymers formed into desired structures. The substituents may be halogens or alkyl groups, such as bromine, chlorine or Ci to C4 alkyl groups; or a methyl group. Alkenyl groups comprise straight or branched carbon chains having one or more double bonds, or one double bond. The alkenyl groups useful for the vinylidene substituted aromatic monomers may include those that when bonded to an aromatic ring are capable of polymerization to form copolymers. The alkenyl groups may have 2 to 10 carbon atoms, 2 to 4 carbon atoms or 2 carbon atoms. Exemplary substituted aromatic monomers include styrene, alpha methyl styrene, N-phenyl-maleimide and chlorinated styrenes; or alpha- methyl styrene and styrene. The vinylidene substituted aromatic monomers may be mono- vinylidene aromatic monomers, which contain one unsaturated group. Vinylidene aromatic monomers include but are not limited to those described in U.S. Pat. Nos. 4,666,987; 4,572,819 and 4,585,825, which are herein incorporated by reference. The monomer may correspond to the formula: wherein R ¹ is separately in each occurrence hydrogen or methyl; and Ar is separately in each occurrence an aromatic group. Ar may contain one or more aromatic rings, may contain one or two aromatic rings, or may contain one aromatic ring n is separately in each occurrence 1 to 3, 1 to 2 or 1. The aromatic rings can be unsubstituted or substituted with a substituent that does not interfere with polymerization of the vinylidene substituted aromatic monomers, or the fabrication of the polymers formed into desired structures. The substituents may be halogens or alkyl groups, such as bromine, chlorine or Ci to C4 alkyl groups; or a methyl group.

[0039] Examples of vinyl halides and vinylidene halides that may be suitable include vinyl chloride, vinyl fluoride, vinylidene chloride, vinylidene fluoride, and lfluoro-l-chloroethylene. [0040] Examples of a- olefins include C3 to C20 a- olefins such as propylene, isobutylene, 1- butene, 1-hexene, 1-pentene, 4-methyl-l-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, and the like. Examples of cycloalkenes include C3 to C20 cycloalkenes such as cyclopentene, cyclohexene and cyclooctene.

[0041] Examples of allyl comonomers that may be useful contain at least one allyl or substituted allyl group (CH2=CR-CH2-, where R is hydrogen or an alkyl group). Preferred allyl monomers include allylic alcohols, allyl ethers, allyl esters, allyl amines, and allyl carbonates. Allylic alcohols used in the process preferably have the general structure CH2=CR-CH2-0H, in which R is hydrogen or a Ci to C10 alkyl group. Suitable allylic alcohols include, for example, allyl alcohol, methallyl alcohol, 2-ethyl-2-propen-l-ol, 2-pentyl-2-propen-l-ol, and the like and mixtures thereof.

[0042] Allylic alcohols may also include alkoxylated allylic alcohols of the formula CH2=CR'CH2{A)n -OH in which R' is hydrogen or methyl, A is a C2-C4 oxyalkylene group, and n, which is the average number of oxyalkylene units in the alkoxylated allylic alcohol, has a value within the range of about 1 to about 5. Suitable propoxylated allyl alcohols can be made, for example, by reacting allyl alcohol with up to 5 equivalents of propylene oxide in the presence of a basic catalyst, as is described in U.S. Pat. Nos. 3,268,561 and 4,618,703, the teachings of which are incorporated herein by reference. Particularly preferred are propoxylated allyl alcohols for which n has a value within the range of 1 to 2. Preferred allyl ethers have the general structure: CH ₂ =CR-CH ₂ -0-R' in which R' is selected from the group consisting of hydrogen and Ci-C ₅ alkyl, and R ¹ is a saturated linear, branched, or cyclic C1-C30 alkyl, aryl, or aralkyl group. Examples of allyl ethers also include epoxy functional allyl ethers (epoxy allyl ethers) such as allyl glycidyl ether. Other exemplary allyl ethers include allyl methyl ether, allyl ethyl ether, allyl tert-butyl ether, allyl methylbenzyl ether, and the like, and mixtures thereof.

[0043] Allyl esters may also be used. Illustratively the allyl esters may have the general structure: CH2 =CR-CH ₂ -0-CO-R' in which R' is selected from R is selected from the group consisting of hydrogen and C1-C5 alkyl, and R ¹ is hydrogen or a saturated or unsaturated linear, branched, or cyclic C1-C30 alkyl, aryl, or aralkyl group. Examples of allyl esters include, for example, allyl formate, allyl acetate, allyl butyrate, allyl benzoate, methallyl acetate, allyl fatty esters, and the like, and mixtures thereof.

[0044] Illustratively the allyl amines may have the general structure: CH2=CR-CH2-NR'R" in which R is selected from the group consisting of hydrogen and C1-C5 alkyl, and R' and R" are hydrogen or a saturated or unsaturated linear, branched, or cyclic C1-C30 alkyl, aryl, or aralkyl group. Examples of allyl amines include allyl amine, N-methyl allyl amine, N-butyl allyl amine, N- benzyl allyl amine, N,N-dimethyl allyl amine, N,N-dibutyl allyl amine, and the like, and mixtures thereof.

[0045] Illustratively the allyl carbonates may have the general structure: CH ₂ =CR-CH ₂ -0-C0 ₂ R', wherein R is selected from the group consisting of hydrogen and C1-C5 alkyl, and R' is a saturated linear, branched, or cyclic C1-C30 alkyl, aryl, or aralkyl group. Examples of allyl carbonates include methyl allyl carbonate, ethyl allyl carbonate, and the like, and mixtures thereof.

[0046] Illustrative vinyl esters that may be of use include those of aliphatic, saturated or unsaturated Ci-C24-carboxylic acids such as, for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, isovaleric acid, caproic acid, caprylic acid, capric acid, undecylenic acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid and melissic acid. Desirably the vinyl esters are of Ci- Ci2-carboxylic acids such as vinyl acetate. Other examples include divinyl adipate, divinyl terephthalate and divinyl cyclohexyl dicarboxylate.

[0047] Illustrative vinyl amides may include known N-vinyl amides such as N-Vinyl pyrrolidone, N-vinylacetamide, N-vinyl valerolactam and N-vinyl caprolactam. [0048] Illustrative vinyl silanes may include known vinyl silanes or vinyl alkoxysilanes or vinyl halosilanes. Examples include vinyltrichlorosilane, vinyltrimethyoxysilane, vinyl triethoxysilane, vinylsilane, vinyltris(2-methoxyethoxy)silane, vinyltrisisopropoxysilane, vinyltris(tert- butylperoxy)silane, vinyldimethylethoxysilane, vinylmethyldicholrosilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane.

[0049] The comonomer may have a nominal functionality slightly less than 1 to any practical amount useful, for example, to provide cross-linking of the copolymer formed from the curable composition. Typically, the nominal functionality is about 1 to 5, 4, 3 or 2.

[0050] The amount of monomer to comonomer may vary over a wide range so long as there is sufficient monomer to facilitate a reasonable photoinitiated cure desired as described below when using a practicable amount of photoinitiator (typically for example 0.1% to 20% by weight of the monomers or the total curable composition). Generally, the ratio of the monomer/comonomer may be from 10/1 to 1/10 and desirable ratios may be dependent on the method used, application characteristics desired or combination thereof. More typically the ratio monomer to comonomer ratio is closer to stoichiometry to enhance the overall rate of cure and conversion such as 5/1, 2/1, 1.5/1, 1.1/ 1 or the inverse of the aforementioned or in essence a stoichiometric amount. The optimum amounts may vary depending on such factors on whether the monomer or comonomer are monofunctional or multifunctional (i.e., have more than one alkene carbon-carbon double bond that may take place in the radiation induced cure). In other words the monomer to comonomer ratio is understood to mean the alkene double bonds in each of the monomer and comonomer and for the comonomer particularly the electron rich carbon- carbon double bond .(i.e., equivalent ratio).

Photoinitiator

[0051] The photoinitiator may be any free radical photoinitiator known in the art that is useful in initiating the radiation cure of the monomer and comonomer. Photoinitiators are well known and are, for example, described in the art such as in "Mechanisms of Photophysical Processes and Photochemical Reactions in Polymers' by J. F. Rabek, pp. 228-337 (1987). Illustrative examples of photoinitiators include the aromatic ketones such as acetophenone, 1- hydroxy-cyclohexyl-phenyl-ketone chlorinated acetophenone, dialkoxyacetophenones, dialkylhydroxyacetophenones, dialkylhydroxyacetophenone alkyl ethers, 1-benzoylcyclohexanol- 2, benzoin, benzoin acetate, benzoin alkyl ethers, dimethoxybenzoin, deoxybenzoin, dibenzyl ketone, acyloxime esters, acylphosphine oxides, acylphosphonates, ketosulphides, dibenzoyl disulphides, and diphenyldithiocarbonate. Mixtures of photoinitiators may be used.

[0052] The photoinitiator may be employed in any amount sufficient to free radically polymerize the curable composition to the desired full or partial cure. The photoinitiator typically is used in an amount of about 0.01 to 20%, or about 0.1 or 0.25 to 8%, or about 0.5 to 5% or about 0.75 to 2% by weight of the curable composition or just the weight of the monomer and comonomer of the curable composition. The photoinitiator can also be polymeric, in which case its amount may be higher due to its higher molecular weight.

[0053] In certain embodiments, the curable composition may be further comprised of a cationic polymerization initiator or anionic polymerization initiator to allow, for example, dual cure of the curable composition. This may be desirable when the C=C bond ratio between the monomer and comonomer is off stoichiometry such as when the monomer/comonomer carbon- carbon double bond ratio is greater than 1.1/1 to 10/1 and less than 1/1.1 to 1/10. Depending on whether the monomer or comonomer is in excess, any suitable cationic or anionic polymerization initiator such as those known in the art may be used. Desirably, the cationic or anionic polymerization initiator is one that is latent and is activated upon being irradiated in a like manner as the radical polymerization initiators described herein. The cationic or anionic initiator may be encapsulated or otherwise be rendered unreactive during the free radical cure and subsequently activated. Likewise, the cationic or anionic initiator may be added after the free radical cure has been initiated or ceased.

[0054] Illustratively, when the monomer is in excess, the curable composition maybe further comprised of a photolatent base such as those described in copending U.S. Provisional Application 62/965,271 incorporated herein by reference in its entirety and in particular paragraph 35. The photolatent base, for example, may one that upon being irradiated release a base such as an amine, guanidine, or amidine and may in some instance also cause radical that can cause radical polymerization. The amount of the cationic or anionic polymerization initiators may be any suitable such as the amounts previously described for the free radical initiator above.

[0055] The curable compositions may be comprised of further components that may vary depending on the application. The further components may be one or more dyes, pigments, toughening agents, impact modifiers, rheology modifiers, natural or synthetic rubbers, filler agents, reinforcing agents, thickening agents, opacifiers, inhibitors, fluorescence markers, thermal degradation reducers, thermal resistance conferring agents, surfactants, wetting agents, or stabilizers can be included in a polymerizable system. For example, thickening agents and plasticizers such as vinyl chloride terpolymer (comprising vinyl chloride, vinyl acetate, and dicarboxylic acid at various weight percentages) and dimethyl sebacate respectively, can be used to modify the viscosity, elasticity, and robustness of a system. In certain embodiments, such thickening agents and other compounds can be used to increase the viscosity of a polymerizable system from about 1 to 3 cPs to about 30,000 cPs, or more.

[0056] According to certain embodiments, stabilizers can be included in the polymerizable compositions to increase and improve the shelf life and to prevent spontaneous polymerization for example, when exposed to ambient lighting. Generally, one or more cationic, anionic polymerization stabilizers and or free-radical stabilizers may be added to the compositions. Anionic polymerization stabilizers are generally electrophilic compounds that scavenge bases and nucleophiles from the composition or growing polymer chain. The use of anionic polymerization stabilizers can terminate additional polymer chain propagation. Cationic polymerization stabilizers are generally nucleophilic compounds that scavenge acids and electrophiles from the composition or growing polymer chain.

[0057] Exemplary anionic polymerization stabilizers typically are acids, exemplary acids may be carboxylic acids, sulfonic acids, phosphoric acids and the like. Exemplary stabilizers include methane sulfonic acid and trifluoroacetic acid. Free-radical stabilizers preferably include phenolic compounds (e.g., 4-methoxyphenol or mono methyl ether of hydroquinone ("MeFIQ") and butylated hydroxy toluene (BFIT)). Stabilizers that may be useful for the curable compositions include those described in U.S. Pat. Nos. 8,609,885; No. 8,884,051 and 6,458,956.

[0058] Exemplary cationic polymerization stabilizers typically are bases such as amines or amides. Exemplary cationic stabilizers include hindered amine compounds and sulfonium sulfate compounds.

[0059] Generally, only minimal quantities of a stabilizer are needed and, in certain embodiments only about 150 parts-per-million or less can be included. In certain embodiments, a blend of multiple stabilizers can be included such as, for example a blend of anionic stabilizers (MSA) and free radical stabilizers (MeFIQ).

[0060] The anionic or cationic polymerization stabilizers are present in sufficient amount to prevent premature polymerization. Preferably, the anionic polymerization stabilizers are present in an amount of about 0.1 part per million or greater based on the weight of the curable composition, more preferably about 1 part per million by weight or greater and most preferably about 5 parts per million by weight or greater. Preferably, the anionic polymerization stabilizers are present in an amount of about 1000 parts per million by weight or less based on the weight of the composition, more preferably about 500 parts per million by weight or less and most preferably about 100 parts per million by weight or less.

[0061] The free radical stabilizers are present in sufficient amount to prevent premature polymerization. Preferably such stabilizers are present in the amounts of from lppm to 3000ppm, however, in some cases higher amounts can be used up to 10,000ppm.

[0062] The curable composition may contain a filler in certain embodiments such as printing dyes or additive manufacturing techniques such as polyjeting and inkjetting, which are described below. Examples of filler include talc, wollastonite, mica, clay, montmorillonite, smectite, kaolin, calcium carbonate, glass fibers, glass beads, glass balloons, glass milled fibers, glass flakes, carbon fibers, carbon flakes, carbon beads, carbon milled fibers, metal flakes, metal fibers, metal coated glass fibers, metal coated carbon fibers, metal coated glass flakes, silica, other ceramic particles, ceramic fibers, ceramic balloons, aramid particles, aramid fibers, polyarylate fibers, graphite, and various whiskers such as potassium titanate whiskers, aluminum borate whiskers and basic magnesium sulfate whiskers. The fillers may be incorporated alone or in combination.

[0063] The curable compositions may be used in any number of applications. Exemplary applications include adhesives, sealants, coatings, components for optical fibers, potting and encapsulating materials for electronics, resins and pre-polymers as raw materials in other systems, and the like. In particular, the curable compositions are useful to manufacture additive manufactured articles and printing dyes on packaging (e.g., plastic packaging).

[0064] The method of forming a copolymer article comprises providing a first layer of curable composition, which is irradiated by radiation, which is useful for applications requiring a single layer such as a printed graphic on a plastic packaging, sealant, or adhesive or the like. In a preferred embodiment, the aforementioned first layer is irradiated, initiating the polymerization and subsequent layers are sequentially layered upon the first layer and irradiated so that the layers chemically bond to the previous layer to form the copolymer article. Such layered copolymer articles may be fashioned by known 3D printing techniques or by hand such as when a dentist fills a tooth.

[0065] When making an article and in particular a layered copolymer article, the nominal functionality of the radical polymerizable double bonds in the monomer, comonomer or both may be 1 or greater such as from about 1 to 10, 4, 3, or 2 or when a crosslinked copolymer is desired. [0066] The irradiation of the layer of the curable composition may be by any suitable apparatus and method such as those known in the art. The wavelength of the radiation may be any useful for a particular application, with ultraviolet being generally applicable. Illustratively, when using UV, the layer may be exposed to ultraviolet radiation having an irradiance of about 0.01 watts/cm ² or more, about 0.25 watt/cm ² or more, or about 0.5 watts/cm ² or more. The ultraviolet may have an irradiance of about 5 watts/cm ² or less, about 4.5 watts/cm ² or less, or about 4 watts/cm ² or less. The ultraviolet may have a wavelength of about 250 nanometers or more, about 300 nanometers or more, or about 325 nanometers of more. The ultraviolet light may have a wavelength of about 400 nanometers or less, about 390 nanometers or less, or about 375 nanometers or less. For example, the ultraviolet light may be emitted between about 325 nanometers and about 375 nanometers. The curable composition may be exposed to the ultraviolet for any useful time such as up to an hour to about 240 seconds or less, about 180 seconds or less, about 120 seconds or less, about 90 seconds or less, about 60 seconds or less, or about 30 seconds or less. The particular irradiance UV or otherwise may be any depending on the photoinitiator having sufficient sensitivity at useful amount as described previously.

[0067] Generally, the UV sources may be any suitable device such as those known in the art and include, for example, UV light emitting diodes (LEDs) and mercury lamps with or without filters that are commercially available.

[0068] The thickness of the layer may be any thickness that is useful to form the copolymer article in a desired time considering the irradiation source and necessity to build subsequent layers thereon in methods such as additive manufacturing. The layer, which may be a film or coating, typically has a thickness of about 0.01 micrometers or greater, about 0.04 micrometers or greater, about 0.1 micrometers or greater, about 0.5 micrometers or greater, or about 1 micrometer or greater to a thickness of about 500 micrometers or less, about 350 micrometers or less, about 160 micrometers or less, about 100 micrometers or less, about 80 micrometers or less or about 60 micrometers or less, about 20 micrometers or less.

[0069] When making a layered copolymer article, exemplary additive manufacturing methods may include, but are not limited to the following photopolymerization 3D printing techniques. Stereolithography (SLA), where a UV laser beam is rastered upon a vat of the curable composition initiating polymerization and is built up layer by layer, which is illustrated by U.S. Pat. Nos 4,575,330 and 5,256,340. Digital light processing (DLP) where an image is flashed at once upon a vat using projections of graphics using conventional light sources employing mirrors typcially, with subsequent layers being built up by changing the image layer by layer (see, for example, U.S. Pat. Nos. 5,236,637 and 10,001,641. Continuous liquid interface production (CLIP) as described in U.S. Pat. No. 9,211, 678 and Daylight polymer printing (DPP) as described in U.S. Pat. Appl. 2018/0141268. Other exemplary 3D printing methods include those employing the polymer as a binder that is sprayed upon a powder bed that is then irradiated and layer built up to form the article (Binder Jetting "BJ" see for example U.S. Pat. No. 5,340,656) or within a printing ink that is irradiated for example layer by layer by using (polyjet or inkjet, see for example, U.S. Pat. Pub. 2018/0029291), or a thin sheet is irradiated with a subsequent sheet layer to the previous sheet and it being irradiated to laminate it to its previous sheet (Sheet lamination, "SL" see for example U.S. Pat. No. 5,876,550). Each of the forgoing patents describing additive manufacturing is incorporated herein by reference as it applies to the method herein.

[0070] The curable composition when employed to make a layered copolymer article advantageously, particularly 3D printed articles, allows for the production of layers having differing composition from one or more of the other layers within the article. Each layer may also be varied within the layer. Different, herein, means that one or more of (i) the monomer is different, (ii) the comonomer is different, (iii) monomer/comonomer ratio is different, (iv) the photoinitiator is different or combination thereof, wherein the difference is readily detectable between each layer. Illustratively, the monomer or comonomer may be different compounds or the ratio between the monomer and comonomer may be different by 10%. Likewise, within a layer the composition may be different in the width and length on a scale much greater than the molecular variation within the polymer itself such as 1mm ² area in the length and width plane. The difference between areas or layers may be determined by statistically significant mechanical property differences of at least 10%, 25% or even 50% (e.g., hardness probes) or by microscopic, spectroscopic techniques in-situ or by disassembly of the article into volumes of an appropriate macroscale (e.g., O.OOlcc to 0.1 cc) subsequently tested for chemistry or property differences and the like.

ILLUSTRATIVE EMBODIMENTS

[0071] The following examples are provided to illustrate the curable compositions and the copolymers formed from them, but are not intended to limit the scope thereof. All parts and percentages are by weight unless otherwise noted. Table 1 shows the monomers, comonomers and electron poor C=C compounds. Cure Test Method

[0072] Each formulation was applied into a cell created by two sheets of passivated glass separated by 860 micrometer spacers. Samples were irradiated with mercury arc lamp spot cure system from Synchron Inc. Double bond conversion was measured by tracking the area of the peak in the absorbance spectrum corresponding to at 6200cm ¹ using Perkin Elmer Spectrum One FTIR spectrometer. Irradiation began at t=0min and continued to t=10min except for Example 2 and Comparative Example 2, which commenced at 0 minutes as shown on Figure 2 for 6 minutes. Each glass plate was first passivated with 1% solution of methanesulfonic acid (MSA) in tetrahydrofuran (THF) followed by rinsing with acetone and ambient drying. The photoinitiator used was 1-hydroxycyclohexyl phenyl ketone, obtained from Millipore Sigma. Initiator level was lwt% for all samples and irradiance at the glass surface was 10 mW/cm ² of UVA. Methylene malonate polyester was synthesized by transesterification of diethyl methylene malonate and 1,4- butanediol.

Table 1 Example 1 and Comparative Examples 1A and IB

[0073] A curable composition was prepared comprised of methylene malonate polyester obtained from transesterification of 1,4-butanediol and diethyl methylene malonate available from Sirrus Inc. Loveland, OH, under the tradename B5200XP, styrene available from Millipore Sigma (Example 1) in a 1:1 molar ratio of carbon-carbon double bonds and photoinitiator as described above. Methylene malonate polyester and styrene were first cured separately from each other (Comparative Examples 1A and IB respectively). The double bond conversion for each monomer is shown in Figure 1.

[0074] As shown in Fig. 1, styrene, Comparative Example IB, did not exhibit a noticeable polymerization after lOmin of UV exposure. When styrene was mixed with the polyester methylene malonate (Example 1) the rate of polymerization was faster than that for the polyester methylene malonate without styrene. Likewise, 95% double bond conversion was achieved after 6 minutes of UV exposure meaning that both methylene malonate polyester and styrene were nearly fully reacted whereas methylene malonate without styrene (Comp. Ex. 1A) did not reach this conversion in the same amount of time.

Examples 2 and Comparative Examples 2A and 2B

[0075] Example 2 was a mixture of the methylene malonate polyester of Example 1, triethylene glycol divinyl ether (TEGDVE) and the photoinitiator. The methylene malonate and TEGDVE were mixed at a 1 to 1 molar ratio of carbon-carbon double bonds. Compositions of methylene malonate polyester and TEGDVE individually with the photoinitiator were also evaluated (Comparative Examples 2A and 2B respectively).

[0076] Figure 2 shows the result of the curing Examples 2 and Comparative Examples 2A and 2B. Like Example 1, the mixture of the methylene malonate polyester with the electron rich TEGDVE resulted in an accelerated double bond conversion at the same UV exposure. From the results the use of the 1,1-dicarbonyl alkene monomer with an electron rich comonomer surprisingly accelerates the radiation induced polymerization of the 1,1-dicarbonyl alkene monomer allowing their effective use in applications requiring rapid curing controlled by irradiation. Examples 3-10 and Comparative Examples 3-11

[0077] In these examples and comparative examples, the monomer was dicyclohexyl methylene malonate (DCHMM) available from Sirrus Inc. Loveland, OH. The comonomers used for each example and comparative example are shown in Table 2. DCHMM and photoinitiator will be referred to Comparative Example 11 and is repeated for convenience in Table 2. The Examples are represented by the column labeled 1:1 equivalent mixture (alkene C=C in the monomer/alkene C=C in the comonomer).

[0078] From Table 2, other than for Examples 7 and 8 and the corresponding Comparative Examples, the conversion rate was substantially faster when the DCHMM was cured with a comonomer of this invention. With regard to Examples 7 and 8, where the comonomer was triallyl isocyanurate and styrene, the rate started slightly slower and then accelerated after the 5% to 10% range used to calculate the rate (not shown) to a faster conversion rate than the DCHMM. The triallyl isocyanurate because it has three C=C rich double bonds did not attain the same conversion and the DCHMM, which is not unexpected because of extensive cross-linking expected from the 3 functionality of the triallyl isocyanurate.

[0079] As to the other Examples in Table 2, it is readily apparent that the rate of conversion was substantially improved with the same or improved overall conversion of the compositions.

Examples 11 and 12 and Comparative Examples 13 to 17

[0080] Figure 5 shows the results of compositions comprised of 4-Tert-Butylcyclohexyl acrylate (TBCH acrylate, Comparative Example 12), TBCH acrylate with DCHMM (Comparative Example 13), TBCH acrylate with TEGDVE (Comparative Example 14), and TBCH acrylate, DCHMM and TEGDVE at the equivalent ratios shown in Figure 5 (Example 11). Figure 6 shows the results of compositions comprised of 3,3,5-Trimethylcyclohexyl methacrylate (TMCH methacrylate, Comparative Example 15), TMCH methacrylate with DCHMM (Comparative Example 16), TMCH methacrylate with TEGDVE (Comparative Example 17), and TMCH methacrylate, DCHMM and TEGDVE at the equivalent ratios shown in Figure 5 (Example 12). In both Figures 5 and 6, it is evident that the acrylate and TEGDVE either have a slow conversion rate or low conversion compared to compositions also including the DCHMM. Likewise, the highest rate of conversion is achieved when both the DCHMM and TEGDVE are present even in the presence of the TMCH methacrylate or TBCH acrylate. Table 2

DCHMM is Comparative Example 11 repeated for convenience in each row.

Co-monomer each are comparative examples.

1:1 equiv mixture each are examples. ^a due to very fast or slow polymerization, polymerization rate Rp determined from conversion range other than 5 to 10%.