(Meth)acrylate-functionalized oligomers and methods for preparing and using such oligomers

Abstract

Provided is a (meth)acrylate-functionalized oligomer having a) an oligomer backbone composed of a first segment and a second segment, and b) (meth)acrylate-functionalized end groups. Such oligomers are useful as components of curable compositions. The first segment, the second segment, and the (meth)acrylate-functionalized end groups are connected by a linkage derived from a polyisocyanate. The first segment is the residue of a first segment precursor having a number average molecular weight of at least 250 Daltons, including a plurality of repeating units and a plurality of isocyanate-reactive functional groups. The second segment is the residue of a second segment precursor different from the first segment precursor, having a number average molecular weight of at least 250 Daltons, including a plurality of repeating units and a plurality of isocyanate-reactive functional groups. The first segment and the second segment exhibit a Hansen Solubility Parameter Distance Relative Energy Difference of at least about 4 and no more than about 9.

Description

[Technical Field]

[0001] The present invention relates to (meth)acrylate-functionalized oligomers, methods for preparing such oligomers, curable compositions based on the oligomers, methods for using the oligomers, and compositions and articles containing the oligomers in cured form. [Background technology]

[0002] Many different types of (meth)acrylate-functionalized oligomers are known in the art, including (meth)acrylate-functionalized urethane oligomers characterized by one or more (meth)acrylate functional groups substituted onto the oligomeric polyurethane backbone (typically at the terminal end of the oligomer). (Meth)acrylate-functionalized urethane oligomers can be synthesized by a variety of methods, including, for example, reacting a polymer polyol, such as a polyether polyol, polycarbonate polyol, or polyester polyol, with an excess of polyisocyanate to form an isocyanate-functionalized urethane prepolymer, and then reacting the isocyanate-functionalized urethane prepolymer with a reagent, such as hydroxyethyl (meth)acrylate, that contains both isocyanate-reactive functionality and (meth)acrylate functionality. Such (meth)acrylate-functionalized urethane oligomers have been found to be useful components of compositions that can be cured (polymerized) using UV radiation or other methods to form cured compositions that function as coatings, adhesives, sealants, additive manufacturing resins, molding resins, and the like.

[0003] For example, U.S. Patent Application Publication No. 2017 / 0158803 A1 describes a urethane acrylic polymer that is the reaction product of a material comprising: [i] a first homopolymer or copolymer polycarbonate polyol; [ii] an organic polyisocyanate; and [iii] a hydroxyl-functional acrylate or methacrylate.

[0004] In another example, U.S. Pat. No. 6,562,881 (B2) discloses urethane (meth)acrylate capped resins prepared from a polyisocyanate component and an alkoxylated adduct of a polyol reacted with a hydroxyalkyl (meth)acrylate.

[0005] Additionally, US Pat. No. 5,219,896 teaches a photocurable liquid coating composition comprising a polycarbonate-based acrylate-terminated polyurethane. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent Application Publication No. 2017 / 0158803 [Patent Document 2] U.S. Patent No. 6,562,881 [Patent Document 3] U.S. Patent No. 5,219,896 [Patent Document 4] U.S. Patent No. 9,676,963 [Patent Document 5] International Publication No. 2014 / 126830 [Patent Document 6] International Publication No. 2014 / 126834 [Patent Document 7] International Publication No. 2014 / 126837 [Non-patent literature]

[0007] [Non-Patent Document 1] Charles Hansen, "Hansen Solubility Parameters: A User's Handbook", 2nd edition (2007), Boca Raton, Fla.: CRC Press., ISBN 978-O-8493-7248-3 [Non-patent document 2] Tumbleston et al., "Continuous Liquid Interface Production of 3D Objects," Science, Vol. 347, No. 6228, pp. 1349-1352 (March 20, 2015) [Non-patent document 3] OCDE (1996), Test No. 118: Determination of the Number-Average Molecular Weight and the Molecular Weight Distribution of Polymers using Gel Permeation Chromatography, OECD Guidelines for the Testing of Chemicals, Section 1, Editions OCDE, Paris Summary of the Invention [Problem to be solved by the invention]

[0008] Although many different types of (meth)acrylate-functionalized urethane oligomers are already known in the art, there remains a need for oligomers that can provide enhanced or improved performance when used as components of curable compositions. In particular, it is desirable to develop new (meth)acrylate-functionalized oligomers that enhance the tensile properties of cured articles, such as films, prepared from curable compositions containing such oligomers. Advantageously, such improved oligomers would have additional attributes such as relatively low viscosity, low haze, and good compatibility with reactive diluents and other components typically utilized in such curable compositions. [Means for solving the problem]

[0009] According to some aspects of the present invention, there is provided a (meth)acrylate-functionalized oligomer composed of, consisting essentially of, or consisting of: a) an oligomeric backbone comprised of a first segment and a second segment; and b) (meth)acrylate-functionalized end groups, wherein the first segment, the second segment, and the (meth)acrylate-functionalized end groups are joined by linkages derived from a polyisocyanate; the first segment is a residue of a first segment precursor comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups and having a number average molecular weight of at least 250 Daltons; the second segment is a residue of a second segment precursor different from the first segment precursor comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups and having a number average molecular weight of at least 250 Daltons; and the first and second segments have a Hansen Solubility Parameter Distance Relative Energy Difference of at least about 4 and no more than about 9.

[0010] Methods for making such oligomers are also provided by the present invention, including reacting the first and second segment precursors sequentially with a polyisocyanate to form an isocyanate-terminated intermediate oligomer, which is then endcapped with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer, and reacting the first and second segment precursors simultaneously with a polyisocyanate to form an isocyanate-terminated intermediate oligomer, which is then endcapped with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer.

[0011] (Meth)acrylate-functionalized oligomers can be cured by a variety of mechanisms, including photocuring, to provide cured compositions with useful properties such as improved tensile strength. The (meth)acrylate-functionalized oligomers can be formulated with other reactive components and other additives to provide curable compositions that can be utilized as coatings, adhesives, sealants, additive modeling resins, and the like. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a graphical illustration comparing the tensile properties of segmented and non-segmented urethane-acrylate oligomers (Examples 5 and 6 and Comparative Examples 7 and 8) in cured form. [Figure 2] The adhesiveness data obtained for the formulations of Examples 9 and 10 are presented in graphical form. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Meth)acrylate-Functionalized Oligomers The (meth)acrylate-functionalized oligomer of the present invention can be described as an oligomeric substance comprising a) an oligomeric backbone comprised of at least one first segment and at least one second segment different from the first segment, and b) (meth)acrylate-functionalized end groups. As used herein, the term "(meth)acrylate" refers to both acrylate and methacrylate. The first segment, the second segment, and the (meth)acrylate-functionalized end groups are connected by linkages derived from polyisocyanates (particularly diisocyanates). The first segment has a number-average molecular weight of at least 250 daltons and is the residue of a first segment precursor comprising multiple repeat units and multiple isocyanate-reactive functional groups. The second segment has a number-average molecular weight of at least 250 daltons and is the residue of a second segment precursor comprising multiple repeat units and multiple isocyanate-reactive functional groups. Additionally, the first segment and the second segment are selected to have a Hansen Solubility Parameter Distance Relative Energy Difference of at least about 4 and no more than about 9.

[0014] The structure of an exemplary (non-limiting) (meth)acrylate-functionalized oligomer according to an embodiment of the present invention can be generally represented as follows (Formula I): Acry-XBXBXAXAXAXAXAXBXBX-Acry (I) [In the formula, A = first segment (residue of first segment precursor containing two isocyanate-reactive functional groups); B = second segment (residue of second segment precursor containing two isocyanate-reactive functional groups); X = diisocyanate-derived linkage; Acry = (meth)acrylate-containing moieties containing (meth)acrylate-functionalized end groups.

[0015] Formula I is an example of a (meth)acrylate-functionalized oligomer having a "segmented" oligomer structure in which a first segment, A, is clustered (forming the segment XAXAXAXAX) and a second segment, B, is also clustered (forming the segment XBXBX).

[0016] The structure of another exemplary (non-limiting) (meth)acrylate-functionalized oligomer according to embodiments of the present invention can be generally represented as follows (Formula II): Acry-XBXBXAXAXBXAXBXAX-Acry (II) [In the formula, A = first segment (residue of first segment precursor containing two isocyanate-reactive functional groups); B = second segment (residue of second segment precursor containing two isocyanate-reactive functional groups); X = diisocyanate-derived linkage; Acry = (meth)acrylate-containing moieties containing (meth)acrylate-functionalized end groups.

[0017] Formula II is an example of a (meth)acrylate-functionalized oligomer having a "statistical" oligomer structure in which first segments A and second segments B are randomly interspersed with one another.

[0018] The first segment A and the second segment B differ from each other in chemical composition. They may also differ from each other in number average molecular weight. Each is the residue of a segment precursor containing two isocyanate-reactive functional groups (e.g., hydroxyl, thiol, primary amino, or secondary amino) and multiple repeating units such as polyether polyol, polyester polyol, or polycarbonate polyol. For example, segments A and B may each correspond to general formula (III'): -O-[polymer]-O- (III') where [polymer] is a polyoxyalkylene, polycarbonate, or polyester chain, with the proviso that A and B are different in composition from each other.

[0019] According to some embodiments of the present invention, X (the linkage derived from diisocyanate) in structural formulas (I) and (II) can be represented by the following formula (IV'): -C(=O)NH-R-NHC(=O)- (IV') where R is an organic moiety such as a hydrocarbyl moiety.

[0020] In the above structural formulas (I) and (II), in some embodiments, "Acryl" (a (meth)acrylate-containing moiety comprising a (meth)acrylate-functionalized end group) may correspond to formula (V'): -YR 1 -OC(=O)CR 2 =CH2(V') [In the formula, R 1 is a divalent organic moiety, and R 2 is H or CH3 and Y is O, S or NR 3 and R 3 is H or an alkyl group (e.g., a C1-C10 alkyl group). In some embodiments, Y is NR 3 and R 3 is a tertiary alkyl group such as a t-butyl, t-amyl (t-pentyl), or t-hexyl group. 1 Examples of alkylenes include, for example, alkylenes (e.g., ethylene, propylene (such as —CHCH(CH)—), butylene), oligo(oxyalkylenes) (e.g., oligo(oxyethylene)), alkoxylated oligo(caprolactone), alkoxylated oligo(lactide), and alkoxylated oligo(caprolactone-co-lactide), and possibly also oligo(caprolactone), oligo(lactide), and oligo(caprolactone-co-lactide).

[0021] According to some embodiments of the present invention, the (meth)acrylate-functionalized oligomer is a liquid at 25° C. In such embodiments, the viscosity of the (meth)acrylate-functionalized oligomer at 25° C. can be, for example, 100,000 centipoise or less, 50,000 centipoise or less, or 25,000 centipoise or less. However, in other embodiments, the (meth)acrylate-functionalized oligomer can be a solid at 25° C. Such a solid (meth)acrylate-functionalized oligomer, when combined with one or more reactive diluents that are liquid at 25° C., can form a composition that is liquid at 25° C. Such a liquid composition can include, for example, up to 40 wt. % of the reactive liquid diluent, based on the weight of the solid (meth)acrylate-functionalized oligomer.

[0022] The number average molecular weight of the (meth)acrylate-functionalized oligomer, as measured by gel permeation chromatography using polystyrene calibration standards, can be varied as desired to achieve target characteristics, such as viscosity and mechanical and physical properties of cured compositions prepared from curable compositions containing the (meth)acrylate-functionalized oligomer. Typically, however, the (meth)acrylate-functionalized oligomer has a number average molecular weight of at least 3000, at least 4000, or at least 5000 daltons, but not more than 30,000 daltons, not more than 20,000 daltons, not more than 18,000 daltons, or not more than 15,000 daltons. For example, the number average molecular weight of the (meth)acrylate-functionalized oligomer can be from 2000 daltons to 30,000 daltons, from 3000 daltons to 20,000 daltons, or from 4000 daltons to 15,000 daltons.

[0023] The (meth)acrylate-functionalized oligomer can have a linear structure, but in other embodiments of the present invention, it can have a star-shaped, radial, or branched structure. According to some aspects of the present invention, a (meth)acrylate functional group is present at each end (terminus) of the (meth)acrylate-functionalized oligomer. The (meth)acrylate-functionalized oligomer according to the present invention can contain only one (meth)acrylate functional group per molecule, but preferably contains two or more (meth)acrylate functional groups per molecule. For example, the (meth)acrylate-functionalized oligomer can contain two, three, four, five, or six (meth)acrylate functional groups per molecule. According to some embodiments, the (meth)acrylate-functionalized oligomer does not contain any ethylenically unsaturated functional groups other than the (meth)acrylate functional group.

[0024] (Meth)acrylate-functionalized oligomers according to the present invention can be prepared using segment precursors, polyisocyanates, (meth)acrylate-functionalized end group precursors, and synthetic methods described in more detail below.

[0025] Segment Precursor The (meth)acrylate-functionalized oligomer of the present invention comprises an oligomer backbone composed of a first segment and a second segment, wherein the first segment is a residue of a first segment precursor having a number average molecular weight of at least 250 Daltons and comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups, and the second segment is a residue of a second segment precursor different from the first segment precursor, having a number average molecular weight of at least 250 Daltons and comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups, and wherein the Hansen Solubility Parameter Distance Relative Energy Difference between the first segment and the second segment is at least about 4 and not more than about 9.

[0026] According to some embodiments, one or both of the first and second segment precursors contain two isocyanate-reactive functional groups per molecule. Typically, the isocyanate-reactive functional groups are present at the terminal ends of the first and second segment precursors. Suitable isocyanate-reactive functional groups include hydroxyl (-OH) groups, including primary, secondary, and tertiary hydroxyl groups; thiol (-SH) groups, including primary, secondary, and tertiary thiol groups; and primary and secondary amino groups (-NH or -NHR, where R can be an organic substituent such as an alkyl group).

[0027] The repeat units present in the first and second segment precursors may be of any known type, including, for example, oxyalkylene, carbonate, and ester repeat units. The repeat units within a particular segment precursor may be identical to one another or different from one another (i.e., the repeat units may be the same or may contain two or more different repeat units, such as both oxyethylene and oxypropylene repeat units when the segment precursor is a polyether polyol).

[0028] The number of repeating units in the segment precursor can be varied as needed to achieve a desired or target number average molecular weight for the resulting segment precursor and corresponding segment in the resulting (meth)acrylate-functionalized oligomer. The segment precursor should have a number average molecular weight of at least 250 Daltons. In other embodiments, the segment precursor has a number average molecular weight of at least 300 Daltons, at least 350 Daltons, or at least 400 Daltons. Generally speaking, it is preferred that the number average molecular weight of the segment precursor be 5000 Daltons or less. In other embodiments, the number average molecular weight of the segment precursor is 4500 Daltons or less or 4000 Daltons or less. For example, the first and second segment precursors can have number average molecular weights of 250-5000 Daltons, 300-4500 Daltons, or 350-4000 Daltons.

[0029] As mentioned above, the first and second segment precursors may differ not only in composition but also in number average molecular weight. According to one embodiment of the present invention, the first segment precursor has a number average molecular weight that differs from the number average molecular weight of the second segment precursor by at least 1000 Daltons.

[0030] The first segment precursor and the second segment precursor should be selected so that, when incorporated into the (meth)acrylate-functionalized oligomer, the first segment and the second segment exhibit a Hansen Solubility Parameter Distance Relative Energy Difference of at least about 4 and not more than about 9. For example, the Hansen Solubility Parameter Distance Relative Energy Difference between the first segment and the second segment can be at least 4 and not more than 8.5.

[0031] The Hansen solubility parameters consist of three parameters that represent the forces acting between molecules of a substance (dispersion forces, polar interaction forces, and hydrogen bonding forces), and can be calculated according to the method proposed by Charles Hansen in his study entitled "Hansen Solubility Parameters: A User's Handbook", 2nd Edition (2007), Boca Raton, Fla.: CRC Press. ISBN 978-O-8493-7248-3. According to this method, three parameters called "Hansen parameters", δ d , δ p , and δ h is sufficient to predict the behavior of a solvent for a given molecule. d (unit: MPa 1 / 2 ) quantifies the energy of intermolecular dispersion forces, i.e., van der Waals forces. The parameter δ p (unit: MPa 1 / 2 ) represents the energy of intermolecular dipole interactions. Finally, the parameter δ h (unit: MPa 1 / 2 ) quantifies the energy derived from intermolecular hydrogen bonds, i.e., the ability to interact through hydrogen bonds. The sum of the squares of three parameters is the Hildebrand solubility parameter (δtot ) squared.

[0032] The three Hansen solubility parameters define a three-dimensional Hansen space. The three Hansen solubility parameters of a material are coordinates in Hansen space. Therefore, the Hansen solubility parameter of a material determines the relative position of the material in Hansen space. The Hansen solubility parameter of a mixture of multiple components is a volume-weighted combination of the Hansen solubility parameters of the individual components that make up the mixture. Therefore, a mixture of multiple components also has a relative position in Hansen space. The Hansen solubility parameter distance (Ra) is the distance in Hansen space between any two materials. Ra can be determined by the following equation 1:

[0033]

number

[0034] [In the formula, δ d1 , δ p1 , and δ h1 are the dispersive, polar, and hydrogen-bonding Hansen solubility parameters of one of the two components, respectively, and δ d2 , δ p2 , and δ h2 are the dispersive, polar, and hydrogen-bonding Hansen solubility parameters of the other of the two components, respectively. The value of the Hansen solubility parameters for a particular component can be determined empirically or can be found in published tables.

[0035] Polymer polyols are particularly suitable for use as segment precursors in the present invention. As used herein, the term "polymer polyol" refers to a polymer having two or more isocyanate-reactive hydroxyl groups per molecule. Preferably, the hydroxyl groups are primary and / or secondary hydroxyl groups. In some embodiments, the hydroxyl groups can be located at the terminal ends of the polymer. However, it is also possible for the hydroxyl groups to be present along the polymer backbone or in side chains or groups pendant to the polymer backbone. According to a preferred embodiment, the polymer polyol can contain two isocyanate-reactive hydroxyl groups per molecule (i.e., a polymer diol). The polymer portion of the polymer polyol can consist of multiple repeating units, such as oxyalkylene units, ester units, carbonate units, acrylic units, alkylene units, etc., or combinations thereof.

[0036] According to some embodiments of the present invention, the polymer polyol may be represented by the following formula (III): HO-[polymer]-OH (III) where [polymer] is a polyoxyalkylene, polycarbonate or polyester chain.

[0037] Particularly preferred polymer polyols include polyether polyols and polyester polyols. Suitable polyether polyols include, for example, polytetramethylene glycol (a hydroxyl-functionalized polymer of tetrahydrofuran) and polyethylene glycol (a hydroxyl-functionalized polymer of ethylene oxide). Suitable polyester polyols include, for example, poly(caprolactone), poly(lactide), poly(alkylene glycol adipate), and poly(alkylene glycol succinate).

[0038] Other types of polymer polyols potentially useful in the present invention include polycarbonate polyols, polydiene polyols (eg, polybutadiene diols, including fully or partially hydrogenated polydiene polyols), and polyacrylic polyols.

[0039] The molecular weight of the polymer polyol can be varied as needed or desired to achieve specific properties in the (meth)acrylate-functionalized urethane oligomer prepared therefrom and / or in the curable composition comprising the (meth)acrylate-functionalized urethane oligomer, and / or in the cured composition obtained by curing the curable composition. For example, the number average molecular weight of the polymer polyol can be at least 300, at least 350, or at least 400 daltons. In other embodiments, the polymer polyol can have a number average molecular weight of 5000 daltons or less, 4500 daltons or less, or 4000 daltons or less. For example, the polymer polyol can have a number average molecular weight of 250 to 5000 daltons, 300 to 4500 daltons, or 350 to 4000 daltons.

[0040] Polyisocyanate To prepare the (meth)acrylate-functionalized oligomer according to the present invention, a polyisocyanate or a mixture of different polyisocyanates can be utilized. As used herein, the term "polyisocyanate" refers to an organic compound containing two or more isocyanate (-NCO) functional groups per molecule. According to a preferred embodiment, the polyisocyanate is a diisocyanate. In other preferred embodiments, the polyisocyanate is an aliphatic polyisocyanate (including cycloaliphatic polyisocyanates) or an aromatic polyisocyanate.

[0041] According to some embodiments of the present invention, the polyisocyanate is a diisocyanate that can be represented by formula (IV): OCN-R-NCO (IV) wherein R is a divalent organic moiety, such as a divalent hydrocarbyl moiety.

[0042] Specific examples of suitable polyisocyanates include, but are not limited to, isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), dicyclohexylmethane 4,4′-diisocyanate (sometimes referred to as methylene dicyclohexyl diisocyanate or hydrogenated MDI (HMDI)), hexamethylene diisocyanate (1,6-hexane diisocyanate), 4,4′-methylenebis(phenylisocyanate), xylene diisocyanate, bitolidine diisocyanate (O-tolidine diisocyanate), 1,5-naphthylene diisocyanate, naphthalene diisocyanate, dianisidine diisocyanate, and polymethylene polyphenylisocyanate, including oligomers thereof. Examples of preferred polyisocyanates include toluene diisocyanate (e.g., 2,4-toluene diisocyanate and 2,6-toluene diisocyanate), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (e.g., 2,2,4-trimethylhexamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate), xylylene diisocyanate (1,3-diisocyanatomethylbenzene), hydrogenated xylylene diisocyanate (sometimes referred to as 1,3-diisocyanatomethylcyclohexane), methylenebis(4-isocyanatocyclohexane) (sometimes referred to as hydrogenated MDI or methylene-bis-cyclohexane diisocyanate), and combinations thereof.

[0043] Precursors of (meth)acrylate functionalized end groups The (meth)acrylate-functionalized end groups of the (meth)acrylate-functionalized oligomer can be formed from or derived from an isocyanate-reactive (meth)acrylate-functionalized compound. Therefore, the isocyanate-reactive (meth)acrylate-functionalized compound can be considered a precursor to the (meth)acrylate-functionalized end groups. The isocyanate-reactive (meth)acrylate-functionalized compound contains at least one (preferably only one) functional group that reacts with an isocyanate functional group, such as the isocyanate functional group of a polyisocyanate or the isocyanate functional group of an isocyanate-terminated intermediate oligomer formed by the reaction of the polyisocyanate with the first and / or second segment precursor. The isocyanate-reactive functional group can be, for example, a hydroxyl group (which, when reacted with an isocyanate group, gives a urethane group [-OC(=O)-NH-]), a primary or secondary amino group (which, when reacted with an isocyanate group, gives a urea group [-NR-C(=O)-NH-]), or a thiol group (which, when reacted with an isocyanate group, gives a thiourethane group [-SC(=O)-NH-]). The isocyanate-reactive (meth)acrylate-functionalized compound further comprises at least one (preferably only one) (meth)acrylate functional group.

[0044] According to some aspects of the present invention, an isocyanate-reactive (meth)acrylate-functionalized compound having a structure according to formula (V) is used. HYR 1 -OC(=O)CR 2 =CH2(V) [In the formula, R 1 is a divalent organic moiety, and R 2 is H or CH3 and Y is O, S or NR 3 and R 3 is H or an alkyl group (e.g., a C1-C10 alkyl group). In some embodiments, Y is NR 3 and R 3 is a tertiary alkyl group such as a t-butyl, t-amyl (t-pentyl), or t-hexyl group. 1Examples of alkylenes include, for example, alkylenes (e.g., ethylene, propylene (such as —CHCH(CH)—), butylene), oligo(oxyalkylenes) (e.g., oligo(oxyethylene)), alkoxylated oligo(caprolactone), alkoxylated oligo(lactide), and alkoxylated oligo(caprolactone-co-lactide), and possibly also oligo(caprolactone), oligo(lactide), and oligo(caprolactone-co-lactide).

[0045] Thus, according to some embodiments of the present invention, the at least one isocyanate-reactive (meth)acrylate-functionalized compound is selected from the group consisting of N-alkylaminoalkyl (meth)acrylates; epoxy (meth)acrylates (reaction products of (meth)acrylic acid and epoxides); hydroxyalkyl (meth)acrylates (hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, 1,6-hexanediol mono(meth) ... ,4-cyclohexanediol mono(meth)acrylate, etc.); alkoxylated hydroxyalkyl (meth)acrylates (diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, etc.); alkoxylated oligo(caprolactone) (meth)acrylate; alkoxylated oligo(lactide) (meth)acrylate; alkoxylated oligo(caprolactone-co-lactide) (meth)acrylate; and combinations thereof. Oligo(caprolactone) (meth)acrylate, oligo(lactide) (meth)acrylate, and oligo(caprolactone-co-lactide) (meth)acrylate may also be utilized.

[0046] Examples of suitable N-alkylaminoalkyl (meth)acrylates include, but are not limited to, tert-butylaminoethyl (meth)acrylate; tert-pentylaminoethyl (meth)acrylate; tert-hexylaminoethyl (meth)acrylate; and tert-butylaminopropyl (meth)acrylate.

[0047] Reaction of an isocyanate functional group (e.g., an isocyanate functional group of a polyisocyanate) with an isocyanate-reactive (meth)acrylate-functionalized compound having a structure according to formula (V) incorporates a (meth)acrylate-functionalized group having a structure according to formula (V') into the oligomer. -YR 1 -OC(=O)CR 2 =CH2(V') [In the formula, R 1 is a divalent organic moiety, and R 2 is H or CH3, and Y is O or NR 3 and R 3 is H or an alkyl group (for example, a C1 to C10 alkyl group).

[0048] The isocyanate-reactive (meth)acrylate-functionalized compound can be a monoester (containing only one (meth)acrylate functional group per molecule) or a polyfunctional ester (containing two, three, or more (meth)acrylate functional groups per molecule). Examples of suitable polyfunctional esters include pentaerythritol tri(meth)acrylate and trimethylolpropane di(meth)acrylate.

[0049] According to some embodiments, the isocyanate-reactive (meth)acrylate-functionalized compound is selected so that the resulting urethane, thiourethane, or urea group formed in the (meth)acrylate-functionalized urethane oligomer can function as a masked or blocked isocyanate group, and under some conditions (e.g., heating at temperatures above 100°C), the urethane or urea-forming reaction is reversible. See, e.g., U.S. Pat. No. 9,676,963, the teachings of which are incorporated herein by reference in their entirety for all purposes.

[0050] Exemplary Methods for Making (Meth)acrylate-Functionalized Oligomers Two exemplary methods for preparing (meth)acrylate-functionalized oligomers according to the present invention can be described as follows.

[0051] Method 1: The (meth)acrylate-functionalized oligomer according to the present invention can be prepared by at least the following steps: a) reacting a first segment precursor having a number average molecular weight of at least 250 Daltons and comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups with a polyisocyanate to obtain a first isocyanate-terminated intermediate oligomer; b) reacting the first isocyanate-terminated intermediate oligomer with additional polyisocyanate and a second segment precursor having a number average molecular weight of at least 250 Daltons and comprising a plurality of repeat units and a plurality of isocyanate-reactive functional groups to obtain a second isocyanate-terminated intermediate oligomer; c) reacting the second isocyanate-terminated intermediate oligomer with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer; wherein the first segment precursor and the second segment precursor differ in composition from each other, and the Hansen Solubility Parameter Distance Relative Energy Difference between the first segment and the second segment is at least 4 and not more than 9. The resulting (meth)acrylate-functionalized oligomer has a segmented structure.

[0052] In step a), a stoichiometric excess of polyisocyanate relative to the isocyanate-reactive functional groups of the first segment precursor is preferably used. For example, amounts of polyisocyanate and first segment precursor effective to provide an NCO:OH ratio of about 1.1 to about 1.8 can be utilized. The reaction of the isocyanate groups of the polyisocyanate with the desired isocyanate-reactive functional groups can be facilitated by the use of a suitable urethane catalyst (described in more detail below). The polyisocyanate can be charged to a suitable reaction vessel and heated to a suitable temperature (e.g., 30°C to 60°C) with stirring. If a urethane catalyst is used, the urethane catalyst can be charged together with the polyisocyanate or can be introduced after the polyisocyanate has been heated to the desired temperature and then mixed with the polyisocyanate. The first segment precursor can then be charged to the reaction vessel and combined with the polyisocyanate and optional urethane catalyst, preferably while mixing the contents of the reaction vessel. The first segment precursor is preferably added to the reaction vessel incrementally, typically over a period of 10 minutes to 2 hours. An exotherm may be observed as a result of the reaction between the polyisocyanate and the first segment precursor. Once the first segment precursor has been added, heating and stirring of the reaction mixture may be continued for a time effective to react all of the isocyanate-reactive functional groups of the second segment precursor (typically about 1 to 10 hours). The temperature of the reaction mixture may be maintained at a temperature of, for example, 60°C to 110°C. Preferably, step a) is carried out in an atmosphere of an inert (oxygen-free) gas, such as nitrogen, excluding moisture. The reaction mixture may be sparged with an inert gas. Step a) generally produces a first isocyanate-terminated intermediate oligomer having a polyisocyanate residue at each terminal end of the first segment precursor. Typically, at least some chain extension occurs so that two or more molecules of the first segment precursor are linked by a polyisocyanate residue.

[0053] For example, if the polyisocyanate is a diisocyanate and the first segment is a polymeric diol, the first isocyanate-terminated intermediate oligomer may have the structure that can be generally represented as follows: OCN-R-NHC(=O)O[-polymer-OC(=O)NHRNHC(=O)O] m -Polymer-OC(=O)NH-R-NCO [where "polymer" is the polymer portion of the reacted polymeric diol, R is the organic portion corresponding to the non-isocyanate portion of the diisocyanate, and m is an integer greater than or equal to 1], and both contain only segments derived from the first segment precursor (i.e., no segments derived from the second segment precursor are present).

[0054] Following step a), the first isocyanate-terminated intermediate oligomer is reacted with the second segment precursor in step b). The second segment precursor may be added incrementally to the reaction mixture containing the first isocyanate-terminated oligomer over a period of time (e.g., 0.5 to 3 hours) while mixing and heating the reaction mixture. After the addition of the second segment precursor is complete, heating of the reaction mixture is continued for a time and temperature effective to achieve complete reaction between the isocyanate-reactive functional groups of the second segment precursor and the isocyanate groups of the first isocyanate-terminated intermediate oligomer, thereby producing a reaction mixture containing the second isocyanate-terminated intermediate oligomer. Generally speaking, suitable reaction temperatures range from 60°C to 110°C, and suitable reaction times (following the addition of the second segment precursor) range from 1 to 10 hours. Preferably, step b), like step a), is carried out in an atmosphere of an inert (oxygen-free) gas, such as nitrogen, excluding moisture. The reaction mixture may be sparged with an inert gas.

[0055] In step c), the isocyanate groups of the second isocyanate-terminated intermediate oligomer are reacted with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer. Generally speaking, the amount of (meth)acrylate compound is preferably selected to be approximately equivalent, on a molar basis, to the amount of unreacted isocyanate groups. The isocyanate content of the second isocyanate-terminated intermediate oligomer can be measured by any suitable analytical method, such as titration. For example, the molar ratio of isocyanate-reactive functional groups to isocyanate groups can be 0.9:1 to 1.2:1. The (meth)acrylate compound can be combined with the reaction mixture containing the second isocyanate-terminated intermediate oligomer all at once or incrementally. Prior to the addition of the (meth)acrylate, one or more antioxidants or polymerization stabilizers (e.g., hindered phenolic antioxidants) may be combined with the reaction mixture. Furthermore, it is generally desirable to conduct the reaction of the (meth)acrylate compound with the second isocyanate-terminated intermediate oligomer in an oxygen-containing atmosphere, such as a dry air atmosphere. The reaction can be sparged with an oxygen-containing gas prior to the addition of the (meth)acrylate compound, and the sparge is maintained during and after the addition. The reaction mixture can be maintained at a temperature and for a time effective to achieve complete or near-complete reaction of the isocyanate present. For example, the reaction mixture can be heated to 60°C to 110°C for 0.5 to 6 hours.

[0056] Method 2: The (meth)acrylate-functionalized oligomer according to the present invention can be prepared by at least the following steps: a) reacting a mixture of a first segment precursor having a number average molecular weight of at least 250 Daltons, the first segment precursor comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups, and a second segment precursor having a number average molecular weight of at least 250 Daltons, the second segment precursor comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups, with a polyisocyanate to obtain an isocyanate-terminated intermediate oligomer; b) reacting the isocyanate-terminated intermediate oligomer with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer; wherein the first segment precursor and the second segment precursor are different in composition from each other, and the Hansen Solubility Parameter Distance Relative Energy Difference between the first segment and the second segment is at least 4 and not more than 9. The resulting (meth)acrylate-functionalized oligomer has a statistical structure.

[0057] In step a), a stoichiometric excess of polyisocyanate relative to the isocyanate-reactive functional groups of the first and second segment precursors is preferably used. The molar ratio of NCO:isocyanate-reactive functional groups can be varied as desired to control the degree of chain extension and, therefore, the number average molecular weight of the final (meth)acrylate-functionalized oligomer. For example, amounts of polyisocyanate and first and second segment precursors effective to produce an NCO:OH ratio of about 1.1 to about 1.8 can be utilized. The desired reaction between the isocyanate groups of the polyisocyanate and the isocyanate-reactive functional groups can be promoted by the use of a suitable urethane catalyst. Such catalysts can be selected from the types of urethane catalysts discussed below. The polyisocyanate, first segment precursor, second segment precursor, and optional urethane catalyst can be combined in a suitable reaction vessel at room temperature (e.g., 20°C to 30°C) and then heated with stirring to a suitable temperature (e.g., 60°C to 110°C) to induce the desired reaction between the isocyanate groups of the polyisocyanate and the isocyanate-reactive functional groups of the first and second segment precursors. Heating and stirring of the reaction mixture can be continued for a time effective to react all of the isocyanate-reactive functional groups of the second segment precursor (typically, about 1 to 10 hours). The temperature of the reaction mixture can be maintained at, for example, 60°C to 110°C. Preferably, step a) is carried out in an atmosphere of an inert (oxygen-free) gas, such as nitrogen, free of moisture. The reaction mixture can be sparged with an inert gas. Step a) generally produces an isocyanate-terminated intermediate oligomer having a polyisocyanate residue at each end of the first segment precursor. Typically, at least some chain extension is performed so that multiple molecules of both the first segment precursor and the second segment precursor are linked by polyisocyanate residues.

[0058] For example, if the polyisocyanate is a diisocyanate and the first segment precursor and the second segment precursor are both polymeric diols, the isocyanate-terminated intermediate oligomer may have the structure that can be generally represented as follows: OCN-R-NHC(=O)O[-polymer-OC(=O)NHRNHC(=O)O] n -Polymer-OC(=O)NH-R-NCO [wherein "polymer" is the polymer portion of the reacted polymeric diol, R is the organic moiety corresponding to the non-isocyanate portion of the diisocyanate, and n is an integer greater than or equal to 1], and comprises both one or more segments derived from a first segment precursor and one or more segments derived from a second segment precursor, the first and second segments being statistically randomly positioned relative to one another. It is recognized that as a result of the method by which such a reaction product comprising an isocyanate-terminated intermediate oligomer is made, the reaction product is a mixture of oligomers of various chain lengths having different numbers of first and second segments within each oligomer molecule.

[0059] In step b) of Method 2, the isocyanate groups of the isocyanate-terminated intermediate oligomer are reacted with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer. Generally speaking, the amount of (meth)acrylate compound is preferably selected to be approximately equivalent, on a molar basis, to the amount of unreacted isocyanate groups. The isocyanate content of the second isocyanate-terminated intermediate oligomer can be measured by any suitable analytical method, such as titration. For example, the molar ratio of isocyanate-reactive functional groups to isocyanate groups can be 0.9:1 to 1.2:1. The (meth)acrylate compound can be combined with the reaction mixture containing the second isocyanate-terminated intermediate oligomer all at once or incrementally. Prior to the addition of the (meth)acrylate, one or more antioxidants or polymerization stabilizers (e.g., hindered phenolic antioxidants) may be combined with the reaction mixture. Furthermore, it is generally desirable to conduct the reaction of the (meth)acrylate compound with the second isocyanate-terminated intermediate oligomer in an oxygen-containing atmosphere, such as a dry air atmosphere. The reaction can be sparged with an oxygen-containing gas before adding the (meth)acrylate compound to maintain dispersion during and after the addition. The reaction mixture can be maintained at a temperature and for a time effective to achieve complete or near-complete reaction of any isocyanates present. For example, the reaction mixture can be heated to 60°C to 110°C for 0.5 to 6 hours.

[0060] Urethane catalyst According to some embodiments of the present invention, one or more urethane catalysts are used in the preparation of (meth)acrylate-functionalized oligomers. As used herein, "urethane catalyst" refers to a substance that can catalyze the reaction of an active hydrogen-containing group (such as a hydroxyl group, a thiol group, or a primary or secondary amino group) with an isocyanate group to form a urethane linkage (in the case of a hydroxyl group), a thiourethane linkage (in the case of a thiol group), or a urea linkage (in the case of an amino group). Thus, the urethane catalyst can accelerate the rate at which such a reaction occurs at a given temperature and / or can achieve a target degree of completion of such a reaction at a temperature lower than the temperature at which the target degree of completion would be achieved in the absence of the urethane catalyst.

[0061] Any tin-based urethane catalyst known in the art may be utilized. However, according to some preferred embodiments, a non-tin urethane catalyst or a combination of non-tin urethane catalysts is used. In some embodiments, the intermediate reaction mixture and the resulting product comprising the (meth)acrylate-functionalized oligomer are free or substantially free of any tin urethane catalyst. For example, the reaction mixture in each stage, as well as the final reaction product and curable composition, may contain less than 500 ppb tin, less than 400 ppb tin, less than 300 ppb tin, less than 200 ppb tin, or less than 100 ppb tin.

[0062] Suitable non-tin urethane catalysts include, for example, one or more non-tin urethane catalysts selected from the group consisting of bismuth carboxylate complexes (such as bismuth octoate); zirconium acetylacetonate complexes; hafnium acetylacetonate complexes; titanium acetylacetonate complexes; zirconium β-diketiminate complexes; hafnium β-diketiminate complexes; titanium β-diketiminate complexes; zirconium amidinate complexes; hafnium amidinate complexes; titanium amidinate complexes; zinc carboxylate complexes; tertiary amines; imidazoles; N-heterocyclic carbenes; (pseudo)tetraalkylammonium halides; phosphines; and combinations thereof.

[0063] Typically, the urethane catalyst is utilized in an amount of 0.0001 to 0.1 weight percent based on the total weight of the final (meth)acrylate-functionalized oligomer.

[0064] Curable compositions containing (meth)acrylate-functionalized oligomers While the (meth)acrylate-functionalized oligomers of the present invention can be used by themselves as curable compositions (i.e., compositions that can be cured to provide a polymerized, hardened material), in another aspect of the present invention, one or more (meth)acrylate-functionalized oligomers according to the present invention can be formulated with one or more additives (i.e., materials other than the (meth)acrylate-functionalized oligomers of the present invention) to provide curable compositions. Such additives can include, for example, reactive diluents, oligomers other than the (meth)acrylate-functionalized oligomers of the present invention (particularly (meth)acylate-functionalized oligomers), stabilizers, initiators (including photoinitiators), fillers, pigments, etc., and combinations thereof. Any of the additives known or used in the curable (meth)acrylate resin art can also be used with the (meth)acrylate-functionalized oligomers of the present invention to formulate curable compositions that are useful for a wide variety of end uses. Some of these additives are discussed in more detail below.

[0065] Additional reactive components The curable composition can be formulated to include one or more additional components that can react with the (meth)acrylate-functionalized oligomer according to the present invention. That is, such additional components are covalently bonded to the polymer matrix formed upon curing of the curable composition. Such additional reactive components typically contain one or more ethylenically unsaturated functional groups per molecule, particularly one or more (meth)acrylate functional groups per molecule. The additional reactive components can be monomers or oligomers, as described in more detail below.

[0066] The relative amounts of the (meth)acrylate-functionalized oligomer according to the present invention and the additional reactive component (such as other (meth)acrylate-functionalized compounds) in the curable composition are not considered critical and may vary widely depending on the particular components selected for use and the properties desired in the curable composition and the resulting cured composition. For example, the curable composition may consist of 0.5 to 99.5 wt. % of the (meth)acrylate-functionalized oligomer according to the present invention and 0.5 to 99.5 wt. % of the additional reactive component, based on the total weight of the (meth)acrylate-functionalized oligomer according to the present invention and the additional reactive component.

[0067] Suitable (meth)acrylate-functionalized compounds include both (meth)acrylate-functionalized monomers and (meth)acrylate-functionalized oligomers.

[0068] According to some embodiments of the present invention, the curable composition comprises, in addition to at least one (meth)acrylate-functionalized oligomer according to the present invention, at least one (meth)acrylate-functionalized monomer containing two or more (meth)acrylate functional groups per molecule. Examples of useful (meth)acrylate-functionalized monomers containing two or more (meth)acrylate functional groups per molecule include acrylic and methacrylic acid esters of polyhydric alcohols (organic compounds containing two or more, e.g., 2 to 6, hydroxyl groups per molecule). Specific examples of suitable polyhydric alcohols include C -acrylate esters, in which the carbon chain may be branched. 2~20 Alkylene glycol (C 2~10Glycols having alkylene groups may be preferred, such as ethylene glycol, trimethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, tetramethylene glycol (1,4-butanediol), 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,12-dodecanediol, cyclohexane-1,4-dimethanol, bisphenols, and hydrogenated bisphenols, as well as their alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives, for example, obtained by reacting 1 to 20 moles of alkylene oxide, such as ethylene oxide and / or propylene oxide, with 1 mole of glycol, diethylene glycol, glycerin, alkoxylated Glycerin, triethylene glycol, dipropylene glycol, tripropylene glycol, trimethylolpropane, alkoxylated trimethylolpropane, ditrimethylolpropane, alkoxylated ditrimethylolpropane, pentaerythritol, alkoxylated pentaerythritol, dipentaerythritol, alkoxylated dipentaerythritol, cyclohexanediol, alkoxylated cyclohexanediol, cyclohexanedimethanol, alkoxylated cyclohexanedimethanol, norbornene dimethanol, alkoxylated norbornene dimethanol, norbornane dimethanol, alkoxylated norbornane dimethanol, polyols containing aromatic rings, cyclohexane-1,4-dimethanol ethylene oxide adduct, bisphenol ethylene oxide adduct Examples of suitable polyhydric alcohols include hydrogenated bisphenol ethylene oxide adducts, bisphenol propylene oxide adducts, hydrogenated bisphenol propylene oxide adducts, cyclohexane-1,4-dimethanol propylene oxide adducts, sugar alcohols, and alkoxylated sugar alcohols. Such polyhydric alcohols may be fully or partially esterified (with (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride, etc.), provided that they contain at least two (meth)acrylate functional groups per molecule. As used herein, the term "alkoxylated" refers to a compound in which one or more epoxides, such as ethylene oxide and / or propylene oxide, are reacted with active hydrogen-containing groups (e.g., hydroxyl groups) of a base compound, such as a polyhydric alcohol, to form one or more oxyalkylene moieties. For example, 1 to 25 moles of epoxide may be reacted per mole of base compound. According to some embodiments of the present invention, the (meth)acrylate-functionalized monomers used may have a relatively low molecular weight (e.g., 100 to 1,000 daltons).

[0069] Any (meth)acrylate-functionalized oligomer known in the art may be used in the curable compositions of the present invention, provided that the curable compositions contain at least one (meth)acrylate-functionalized oligomer according to the present invention. According to some embodiments, such oligomers contain two or more (meth)acrylate functional groups per molecule. The number average molecular weight of such oligomers can vary widely, for example, from about 500 to about 50,000.

[0070] Suitable (meth)acrylate-functionalized oligomers include, for example, polyester (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, polyether (meth)acrylate oligomers, polyurethane (meth)acrylate oligomers, acrylic (meth)acrylate oligomers, polydiene (meth)acrylate oligomers, polycarbonate (meth)acrylate oligomers, and combinations thereof. Such oligomers can be selected and used in combination with one or more (meth)acrylate-functionalized monomers to enhance flexibility, strength, and / or modulus, among other attributes, of cured resin foams prepared using the multi-component systems of the present invention.

[0071] Exemplary polyester (meth)acrylate oligomers include the reaction product of acrylic acid or methacrylic acid, or a mixture thereof, with a hydroxyl-terminated polyester polyol. The reaction process can be carried out so that all or essentially all of the hydroxyl groups of the polyester polyol are (meth)acrylated, especially when the polyester polyol is difunctional. The polyester polyol can be prepared by the polycondensation reaction of a polyhydroxyl-functional component (particularly a diol) with a polycarboxylic acid-functional compound (particularly a dicarboxylic acid and anhydride). The polyhydroxyl-functional component and the polycarboxylic acid-functional component can each have a linear, branched, alicyclic, or aromatic structure and can be used individually or in mixtures.

[0072] Examples of suitable epoxy (meth)acrylate oligomers include the reaction products of acrylic acid or methacrylic acid, or mixtures thereof, with glycidyl ethers or esters.

[0073] Suitable polyether (meth)acrylate oligomers include, but are not limited to, the condensation reaction products of acrylic acid or methacrylic acid, or a mixture thereof, with polyether polyols (such as polyethylene glycol, polypropylene glycol, or polytetramethylene glycol), which are polyetherols. Suitable polyetherols can be linear or branched materials containing ether linkages and terminal hydroxyl groups. Polyetherols can be prepared by ring-opening polymerization of cyclic ethers such as tetrahydrofuran or alkylene oxides using starting molecules. Suitable starting molecules include water, polyhydroxyl-functional materials, polyester polyols, and amines.

[0074] Polyurethane (meth)acrylate oligomers (sometimes referred to as "urethane (meth)acrylate oligomers") that can be used in the multi-component systems of the present invention include urethanes based on aliphatic and / or aromatic polyester polyols and polyether polyols and aliphatic and / or aromatic polyester diisocyanates and polyether diisocyanates, capped with (meth)acrylate end groups. Suitable polyurethane (meth)acrylate oligomers include, for example, aliphatic polyester-based urethane di- and tetra-acrylate oligomers, aliphatic polyether-based urethane di- and tetra-acrylate oligomers, and aliphatic polyester / polyether-based urethane di- and tetra-acrylate oligomers.

[0075] In various embodiments, polyurethane (meth)acrylate oligomers can be prepared by reacting an aliphatic and / or aromatic diisocyanate with an OH-terminated polyester polyol (including aromatic, aliphatic, and mixed aliphatic / aromatic polyester polyols), polyether polyols, polycarbonate polyols, polycaprolactone polyols, polyorganosiloxane polyols (e.g., polydimethylsiloxane polyols), or polydiene polyols (e.g., polybutadiene polyols), or combinations thereof, to form an isocyanate-functionalized oligomer, which can then be reacted with a hydroxyl-functionalized (meth)acrylate, such as hydroxyethyl acrylate or hydroxyethyl methacrylate, to form terminal (meth)acrylate groups. For example, the polyurethane (meth)acrylate oligomer can contain two, three, four, or more (meth)acrylate functional groups per molecule.

[0076] Suitable acrylic (meth)acrylate oligomers (sometimes referred to in the art as "acrylic oligomers") include oligomers that can be described as materials having an oligomeric acrylic backbone functionalized with one or more (meth)acrylate groups (which can be at the end of the oligomer or pendant from the acrylic backbone). The acrylic backbone can be a homopolymer, random copolymer, or block copolymer composed of repeating units of acrylic monomers. The acrylic monomer can be any monomeric (meth)acrylate, such as C1-C6 alkyl (meth)acrylates and functionalized (meth)acrylates, such as (meth)acrylates with hydroxyl, carboxylic acid, and / or epoxy groups. Acrylic (meth)acrylate oligomers may be prepared using any procedure known in the art, such as by oligomerizing monomers at least a portion of which are functionalized with hydroxyl, carboxylic acid, and / or epoxy groups (e.g., hydroxyalkyl (meth)acrylate, (meth)acrylic acid, glycidyl (meth)acrylate) to obtain a functionalized oligomeric intermediate, which is then reacted with one or more (meth)acrylate-containing reactants to introduce the desired (meth)acrylate functionality.

[0077] Exemplary (meth)acrylate functionalized monomers and oligomers include ethoxylated bisphenol A di(meth)acrylate; triethylene glycol di(meth)acrylate; ethylene glycol di(meth)acrylate; tetraethylene glycol di(meth)acrylate; polyethylene glycol di(meth)acrylate; 1,4-butanediol diacrylate; 1,4-butanediol dimethacrylate; diethylene glycol diacrylate; diethylene glycol dimethacrylate, 1,6-hexanediol diacrylate; 1,6-hexanediol dimethacrylate; neopentyl glycol diacrylate; neopentyl glycol di(meth)acrylate; polyethylene glycol (600) dimethacrylate (6 00 refers to the approximate number average molecular weight of the polyethylene glycol portion); polyethylene glycol (200) diacrylate; 1,12-dodecanediol dimethacrylate; tetraethylene glycol diacrylate; triethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, tripropylene glycol diacrylate, polybutadiene diacrylate; methylpentanediol diacrylate; polyethylene glycol (400) diacrylate; ethoxylated 2 bisphenol A dimethacrylate; ethoxylated 3 bisphenol A dimethacrylate; ethoxylated 3 bisphenol A diacrylate; cyclohexanedimethanol dimethacrylate; cyclohexanedimethanol diacrylate; ethoxylated 10 Bisphenol A dimethacrylate (the symbol following "ethoxylated" indicates the average number of oxyalkylene moieties per molecule); dipropylene glycol diacrylate; ethoxylated 4 bisphenol A dimethacrylate; ethoxylated 6 bisphenol A dimethacrylate; ethoxylated 8 bisphenol A dimethacrylate; alkoxylated hexanediol diacrylate; alkoxylated cyclohexanedimethanol diacrylate; dodecane diacrylate; ethoxylated 4 bisphenol A diacrylate; ethoxylated 10Bisphenol A diacrylate;Polyethylene glycol (400) dimethacrylate;Polypropylene glycol (400) dimethacrylate;Metal diacrylates;Modified metal diacrylates;Metal dimethacrylates;Polyethylene glycol (1000) dimethacrylate;Methacrylated polybutadiene;Propoxylated 2-neopentyl glycol diacrylate;Ethoxylated 30 Bisphenol A dimethacrylate; ethoxylated 30 Bisphenol A diacrylate;Alkoxylated neopentyl glycol diacrylate;Polyethylene glycol dimethacrylate;1,3-Butylene glycol diacrylate;Ethoxylated 2 bisphenol A dimethacrylate;Dipropylene glycol diacrylate;Ethoxylated 4 bisphenol A diacrylate;Polyethylene glycol (600) diacrylate;Polyethylene glycol (1000) dimethacrylate;Tricyclodecane dimethanol diacrylate;Propoxylated 2 neopentyl glycol diacrylate;Alkoxylated diacrylates of fatty alcohols, trimethylolpropane trimethacrylate;Trimethylolpropane triacrylate;Tris(2-hydroxyethyl) isocyanurate triacrylate;Ethoxylated 20 Trimethylolpropane triacrylate;Pentaerythritol triacrylate;Ethoxylated 3 trimethylolpropane triacrylate;Propoxylated 3 trimethylolpropane triacrylate;Ethoxylated 6 trimethylolpropane triacrylate;Propoxylated 6 trimethylolpropane triacrylate;Ethoxylated 9 trimethylolpropane triacrylate;Alkoxylated trifunctional acrylates;Trifunctional methacrylates;Trifunctional acrylates;Propoxylated 3 glyceryl triacrylate;Propoxylated 5.5 Glyceryl triacrylate; ethoxylated 15Trimethylolpropane triacrylate;Trifunctional phosphate esters;Trifunctional acrylate esters;Pentaerythritol tetraacrylate;Di-trimethylolpropane tetraacrylate;Ethoxylated 4-pentaerythritol tetraacrylate;Pentaerythrilol polyoxyethylene tetraacrylate;Dipentaerythritol pentaacrylate;Pentaacrylic acid esters;Epoxy acrylate oligomers;Epoxy methacrylate oligomers;Urethane acrylate oligomers;Urethane methacrylate oligomers;Polyester acrylate oligomers; Included are polyester methacrylate oligomers; stearyl methacrylate oligomers; acrylic acrylate oligomers; perfluorinated acrylate oligomers; perfluorinated methacrylate oligomers; aminoacrylate oligomers; amine-modified polyether acrylate oligomers; and amino methacrylate oligomers.

[0078] The curable compositions of the present invention can optionally include one or more (meth)acrylate-functionalized compounds containing only one acrylate or methacrylate functional group per molecule (referred to herein as "mono(meth)acrylate-functionalized compounds"). Any such compounds known in the art can be used.

[0079] Examples of suitable mono(meth)acrylate functionalized compounds include mono-(meth)acrylic acid esters of aliphatic alcohols (the aliphatic alcohols can be linear, branched, or alicyclic and can be mono-alcohols, di-alcohols, or polyalcohols, provided that only one hydroxyl group is esterified with (meth)acrylic acid); mono-(meth)acrylic acid esters of aromatic alcohols (such as phenol, including alkylated phenols); mono-(meth)acrylic acid esters of alkylaryl alcohols (such as benzyl alcohol); mono-(meth)acrylic acid esters of oligomeric and polymeric glycols, such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, and polypropylene glycol. ) acrylic acid esters); mono-(meth)acrylic acid esters of monoalkyl ethers of glycols, oligomeric glycols, polymeric glycols; mono-(meth)acrylic acid esters of alkoxylated (e.g., ethoxylated and / or propoxylated) fatty alcohols (the fatty alcohol can be linear, branched, or alicyclic and can be a mono-alcohol, di-alcohol, or polyalcohol, provided that only one hydroxyl group of the alkoxylated fatty alcohol is esterified with (meth)acrylic acid); mono-(meth)acrylic acid esters of alkoxylated (e.g., ethoxylated and / or propoxylated) aromatic alcohols (such as alkoxylated phenols); caprolactone mono(meth)acrylate, and the like.

[0080] The following compounds are illustrative of mono(meth)acrylate-functionalized compounds suitable for use in the curable compositions of the present invention: methyl (meth)acrylate; ethyl (meth)acrylate; n-propyl (meth)acrylate; n-butyl (meth)acrylate; isobutyl (meth)acrylate; n-hexyl (meth)acrylate; 2-ethylhexyl (meth)acrylate; n-octyl (meth)acrylate; isooctyl (meth)acrylate; n-decyl (meth)acrylate; n-dodecyl ( METHACRYLATES;TRIDECYL(METH)ACRYLATE;TETRADECYL(METH)ACRYLATE;HEXADECYL(METH)ACRYLATE;2-HYDROXYETHYL(METH)ACRYLATE;2- AND 3-HYDROXYPROPYL(METH)ACRYLATE;2-METHOXYETHYL(METH)ACRYLATE;2-ETHOXYETHYL(METH)ACRYLATE;2- AND 3-ETHOXYPROPYL(METH)ACRYLATE;TETRAHYDRofurfuryl(METH)ACRYLATE;ALKOXY-ETHYL TETRAHYDRofurfuryl(METH)ACRYLATE;IRON Isobornyl (meth)acrylate; 2-(2-ethoxyethoxy)ethyl (meth)acrylate; cyclohexyl (meth)acrylate; glycidyl (meth)acrylate; isodecyl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; lauryl (meth)acrylate; isobornyl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; alkoxylated phenol (meth)acrylate; alkoxylated nonylphenol (meth)acrylate; cyclic trimethylolpropane formal (meth)acrylate; trimethylcyclohexanol (meth)acrylate; diethylene glycol monomethyl ether (meth)acrylate; diethylene glycol monoethyl ether (meth)acrylate; diethylene glycol monobutyl ether (meth)acrylate; triethylene glycol monoethyl ether (meth)acrylate; ethoxylated lauryl (meth)acrylate; methoxypolyethylene glycol (meth)acrylate; and combinations thereof.

[0081] According to some desirable embodiments of the present invention, the curable composition comprises at least one (meth)acrylate-functionalized compound that functions as a hydrogen bond donor, such as a compound that contains at least one hydroxyl or amino functional group in addition to the (meth)acrylate functional group.

[0082] stabilizers Generally speaking, it is desirable to include one or more stabilizers in the curable compositions of the present invention to provide sufficient storage stability and shelf life. Advantageously, one or more such stabilizers are present at each stage of the process used to prepare the curable compositions and protect them from undesired reaction between the (meth)acrylate functional groups of the reactive diluent and the isocyanate-reactive (meth)acrylate-functionalized compound during processing. As used herein, the term "stabilizer" refers to a compound or substance that delays or prevents the reaction or curing of the (meth)acrylate functional groups present in the composition in the absence of actinic radiation. However, it is advantageous to select the amount and type of stabilizer so that the composition remains curable when exposed to actinic radiation (i.e., the stabilizer does not interfere with radiation curing of the composition). Typically, stabilizers effective for purposes of the present invention are classified as radical stabilizers (i.e., stabilizers that function by inhibiting radical reactions).

[0083] Any stabilizer known in the art for (meth)acrylate-functionalized compounds can be used in the present invention. Quinones represent a particularly preferred type of stabilizer that can be used in the context of the present invention. As used herein, the term "quinone" includes both quinone and hydroquinone, as well as their ethers, such as monoalkyl, monoaryl, monoaralkyl, and bis(hydroxyalkyl) ethers of hydroquinone. Hydroquinone monomethyl ether is an example of a suitable stabilizer that can be used.

[0084] The concentration of stabilizer in the curable composition will vary depending on the particular stabilizer or combination of stabilizers selected for use, as well as the degree of stabilization desired and the susceptibility of the components in the curable composition to degradation in the absence of the stabilizer. Typically, however, the curable composition is formulated to contain 50 to 5,000 ppm of stabilizer. According to some embodiments of the present invention, the reaction mixture at each stage of the process used to make the curable composition contains at least some stabilizer, for example, at least 50 ppm of stabilizer.

[0085] Photoinitiator In some embodiments of the present invention, the curable compositions described herein comprise at least one photoinitiator and are radiant energy curable. A photoinitiator can be considered any type of substance that, upon exposure to radiation (e.g., actinic radiation), forms a species that initiates a reaction and hardening that polymerizes organic materials present in the curable composition. Suitable photoinitiators include radical photoinitiators, as well as cationic photoinitiators and combinations thereof.

[0086] A radical polymerization initiator is a substance that forms radicals when irradiated. The use of radical photoinitiators is particularly preferred. Non-limiting types of radical photoinitiators suitable for use in the curable compositions of the present invention include, for example, benzoin, benzoin ether, acetophenone, benzil, benzil ketal, anthraquinone, phosphine oxide, α-hydroxyketone, phenylglyoxylate, α-aminoketone, benzophenone, thioxanthone, xanthone, acridine derivatives, phenazene derivatives, quinoxaline derivatives, and triazine compounds.

[0087] The amount of photoinitiator can vary as may be appropriate depending on, among other factors, the photoinitiator selected, the amount and type of polymerizable species present in the curable composition, the radiation source and radiation conditions used, but typically the amount of photoinitiator can be from 0.05% to 5% by weight, preferably from 0.1% to 2% by weight, based on the total weight of the curable composition.

[0088] Other additives The curable compositions of the present invention can optionally contain one or more additives in place of or in addition to the above components, including, but not limited to, antioxidants / light stabilizers, light screeners / absorbers, polymerization inhibitors, antifoaming agents, flow or leveling agents, colorants, pigments, dispersants (wetting agents, surfactants), slip agents, fillers, chain transfer agents, thixotropic agents, matting agents, impact modifiers, waxes, or a variety of other additives, including any of those commonly utilized in the coating, sealant, adhesive, molding, 3D printing, or ink arts.

[0089] The curable compositions of the present invention can include one or more light-blocking agents (sometimes referred to in the art as absorbers), particularly when the curable compositions are intended for use as resins in three-dimensional printing processes involving photocuring of the curable compositions. Light-blocking agents can be any such substance known in the three-dimensional printing art, including, for example, non-reactive pigments and dyes. Light-blocking agents can be, for example, visible light blockers or UV light blockers. Examples of suitable light-blocking agents include, but are not limited to, titanium dioxide, carbon black, and organic UV absorbers such as hydroxybenzophenone, hydroxyphenylbenzotriazole, oxanilide, benzophenone, thioxanthone, hydroxyphenyltriazine, Sudan I, bromothymol blue, 2,2'-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole) (sold under the trade name "Benetex OB Plus"), and benzotriazole UV absorbers.

[0090] The amount of light-blocking agent can be varied as desired or suitable for a particular application. Generally speaking, when the curable composition contains a light-blocking agent, the light-blocking agent is present in a concentration of 0.001 to 10% by weight, based on the weight of the curable composition.

[0091] Advantageously, the curable compositions of the present invention can be formulated to be solvent-free, i.e., free of any non-reactive volatile materials (materials having a boiling point of 150° C. or less at atmospheric pressure). For example, the curable compositions of the present invention may contain little or no non-reactive solvent, e.g., less than 10%, or less than 5%, or less than 1%, or even 0% of non-reactive solvent based on the total weight of the curable composition.

[0092] According to some aspects of the present invention, the curable composition can be formulated to include one or more chain extenders. Useful chain extenders include compounds (which can be monomers, oligomers, or polymers) having two or more isocyanate-reactive functional groups per molecule. Such isocyanate-reactive functional groups can be reactive with the (meth)acrylate-functionalized urethane oligomer component of the curable composition, and the reaction can involve reaction at urethane or urea groups present in the (meth)acrylate-functionalized urethane oligomer and / or isocyanate groups generated by deblocking such urethane or urea groups.

[0093] Suitable chain extenders include, for example, polyalcohols (e.g., dialcohols), polyamines (e.g., diamines, where the amine groups are primary or secondary), and compounds containing one or more hydroxyl groups and one or more primary and / or secondary amino groups per molecule. Examples of such chain extenders include glycols such as ethylene glycol, propylene glycol, and neopentyl glycol; glycol oligomers (e.g., ethylene glycol oligomers such as diethylene glycol, triethylene glycol, and tetraethylene glycol); 1,3-propanediol; 1,3-butanediol; 1,4-butanediol; 1,6-hexanediol; 1,4-cyclohexanediomethanol; ethanolamine; diethanolamine; methyldiethanolamine; and phenyldiethanol. amines; glycerol; trimethylolpropane; 1,2,6-hexanetriol; triethanolamine; pentaerythritol; N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine; diethyltoluenediamine; dimethylthiotoluenediamine; methylenedicyclohexylamine; hydroquinone bis(2-hydroxyethyl)ether; 4,4'-methylenebis(3-chloro-2,6-diethylaniline); 4,4'-methylenebis(2,6-diethylaniline); 4,4'-methylenebis(2-chloroaniline); and combinations thereof.

[0094] (Meth)acrylate-functionalized oligomers and uses of curable compositions containing (meth)acrylate-functionalized oligomers As mentioned above, the curable compositions prepared according to the present invention can contain one or more photoinitiators and can be photocurable. In some other embodiments of the present invention, the curable compositions described herein do not contain any initiators and can be (at least partially) cured with electron beam energy. In other embodiments, the curable compositions described herein contain at least one radical initiator that decomposes when heated or in the presence of an accelerator, making them chemically curable (i.e., without the need to expose the curable composition to radiation). The at least one radical initiator that decomposes when heated or in the presence of an accelerator can include, for example, a peroxide or an azo compound. Suitable peroxides for this purpose can include any compound, particularly any organic compound, containing at least one peroxy (—OO—) moiety, such as dialkyl, diaryl, and aryl / alkyl peroxides, hydroperoxides, percarbonates, peresters, peracids, acyl peroxides, etc. The at least one accelerator can include, for example, at least one tertiary amine and / or one or more other reducing agents based on metal-containing salts (e.g., carboxylates of transition metals such as iron, cobalt, manganese, vanadium, and combinations thereof). The accelerator can be selected to accelerate decomposition of the radical initiator to generate active radical species at room temperature, such that curing of the curable composition is achieved without the need for heating or baking the curable composition. In other embodiments, no accelerator is present, and the curable composition is heated to a temperature effective to cause decomposition of the radical initiator to generate radical species that initiate curing of the polymerizable compounds present in the curable composition.

[0095] Advantageously, the curable compositions of the present invention can be formulated to be solvent-free, i.e., free of any non-reactive volatile materials (materials having a boiling point of 150°C or less at atmospheric pressure). For example, the curable compositions of the present invention can contain little or no non-reactive solvent, e.g., less than 10%, or less than 5%, or less than 1%, or even 0% of non-reactive solvent based on the total weight of the curable composition. When reactive diluents are utilized in the curable compositions, they can be selected to provide a sufficiently low viscosity of the curable composition, even in the absence of solvent, so that the curable composition can be easily applied to a substrate surface at a suitable application temperature to form a relatively thin, uniform layer.

[0096] In preferred embodiments of the invention, the curable compositions are liquid at 25° C. In various embodiments of the invention, the curable compositions described herein are formulated to have a viscosity of less than 10,000 mPa·s (cP), or less than 5000 mPa·s (cP), or less than 4000 mPa·s (cP), or less than 3000 mPa·s (cP), or less than 2500 mPa·s (cP), or less than 2000 mPa·s (cP), or less than 1500 mPa·s (cP), or less than 1000 mPa·s (cP), or even less than 500 mPa·s (cP), as measured at 25° C. on a Brookfield Viscometer Model DV-II using spindle 27 (spindle speed typically varies between 20 rpm and 200 rpm depending on viscosity). In advantageous embodiments of the invention, the viscosity of the curable composition is 200 to 5000 mPa·s (cP), or 200 to 2000 mPa·s (cP), or 200 to 1500 mPa·s (cP), or 200 to 1000 mPa·s (cP) at 25° C. The relatively high viscosity can provide satisfactory performance in applications where the curable composition is heated above 25° C., such as in three-dimensional printing operations using machines equipped with heated resin vats.

[0097] The curable compositions described herein can be compositions that can be cured by radical polymerization, cationic polymerization, or other types of polymerization. In certain embodiments, the curable compositions are photocured (i.e., cured by exposure to actinic radiation such as light, especially visible or UV light). End uses of the curable compositions include, but are not limited to, inks, coatings, adhesives, additive manufacturing resins (such as 3D printing resins), molding resins, sealants, composites, antistatic layers, electronic applications, recyclable materials, smart materials that can detect and respond to stimuli, and biomedical materials.

[0098] Cured compositions prepared from the curable compositions described herein may be used, for example, in three-dimensional articles (three-dimensional articles that can consist of or can consist essentially of the cured composition), coated articles (articles in which a substrate is coated with one or more layers of the cured composition, including encapsulated articles in which the substrate is completely surrounded by the cured composition), laminated or laminated articles (articles in which a first component of the article is laminated or laminated to a second component by the cured composition), composite articles, or printed articles (articles in which the cured composition is used to imprint graphics or the like onto a substrate such as paper, plastic, or an M-containing substrate).

[0099] Curing of the curable composition according to the present invention can be carried out by any suitable method, such as radical and / or cationic polymerization. One or more initiators, such as a radical initiator (e.g., a photoinitiator, a peroxide initiator), can be present in the curable composition. Prior to curing, the curable composition can be applied to a substrate surface in any known conventional manner, such as by spraying, knife coating, roll coating, casting, drum coating, dipping, or the like, and combinations thereof. Indirect application using a transfer process can also be used. The substrate can be any commercially suitable substrate, such as a high-surface energy substrate or a low-surface energy substrate, such as a metal substrate or a plastic substrate, respectively. Substrates can include metal, paper, cardboard, glass, thermoplastics such as polyolefins, polycarbonate, acrylonitrile butadiene styrene (ABS), and blends thereof, composites, wood, leather, and combinations thereof. When used as an adhesive, the curable composition can be disposed between two substrates and then cured, thereby bonding the substrates to form a laminated article. Curable compositions according to the present invention can also be formed and cured in bulk form (eg, the curable composition can be cast into a suitable mold and then cured).

[0100] Curing can be accelerated or facilitated by providing energy to the curable composition, such as by heating the curable composition and / or exposing the curable composition to a radiation source, such as visible or UV light, infrared light, and / or electron beam radiation. Thus, the cured composition can be considered a reaction product of the curable composition formed by curing. The curable composition can be partially cured by exposure to actinic radiation, and further curing is achieved by heating the partially cured article. For example, an article (e.g., a 3D printed article) formed from the curable composition can be heated at a temperature of 40°C to 120°C for 5 minutes to 12 hours.

[0101] Multiple layers of the curable composition according to the present invention can be applied to a substrate surface. The multiple layers can be cured simultaneously (e.g., by exposure to a single dose of radiation), or each layer can be cured sequentially before applying an additional layer of the curable composition.

[0102] The curable compositions described herein can be used as resins in three-dimensional printing applications. Three-dimensional (3D) printing (sometimes called additive manufacturing) is a method in which 3D digital models are produced by the deposition of build materials. 3D printed objects are created by the sequential construction of two-dimensional (2D) layers or slices corresponding to cross-sections of the 3D object by utilizing computer-aided design (CAD) data of the object. Stereolithography (SL) is a type of additive manufacturing in which a liquid resin is cured by selective exposure to radiation to form each 2D layer. The radiation can be in the form of electromagnetic waves or electron beams. The most commonly applied energy sources are ultraviolet, visible, or infrared.

[0103] The curable compositions of the present invention described herein can be used as 3D printing resin formulations, i.e., compositions intended for use in the manufacture of three-dimensional articles using 3D printing techniques. Such three-dimensional articles can be freestanding / self-supporting and can consist of, or essentially consist of, the cured compositions of the present invention. The three-dimensional articles can also be composites containing at least one component consisting of, or essentially consisting of, the cured compositions described above, as well as at least one additional component (e.g., a metal component or a thermoplastic component) composed of one or more materials other than the cured composition. While other types of three-dimensional (3D) printing methods can also be performed using the curable compositions of the present invention (e.g., SLA, inkjet), the curable compositions of the present invention are particularly useful in digital light printing (DLP). The curable compositions of the present invention can be used in three-dimensional printing operations with other materials that serve as a scaffold or support for the articles formed from the curable compositions of the present invention.

[0104] The curable compositions of the present invention are therefore useful in implementing various types of three-dimensional fabrication or printing techniques, including methods in which the construction of a three-dimensional object is carried out stepwise or layer by layer. In such methods, layer formation can be achieved by solidification (curing) of the curable composition under the action of exposure to radiation, such as visible, UV, or other actinic radiation. For example, a new layer can be formed on the top surface of a growing object or on the bottom surface of a growing object. The curable compositions of the present invention can also be advantageously used in methods for producing three-dimensional objects by additive manufacturing, in which the method is carried out continuously. For example, the object can be produced from a liquid interface. Suitable methods of this type are sometimes referred to in the art as "continuous liquid interface (or interphase) production (or printing)" ("CLIP") methods. Such methods are described, for example, in WO 2014 / 126830; WO 2014 / 126834; WO 2014 / 126837; and Tumbleston et al., "Continuous Liquid Interface Production of 3D Objects," Science, Vol. 347, No. 6228, pp. 1349-1352 (March 20, 2015), the entire disclosures of which are incorporated herein by reference in their entirety for all purposes.

[0105] When stereolithography is performed on an oxygen-permeable build window, the generation of articles using curable compositions according to the present invention can be made possible in a CLIP procedure by creating an oxygen-containing "dead zone," a thin, uncured layer of curable composition between the window and the surface of the cured article as the cured article is formed. In such methods, a curable composition is used, and curing (polymerization) is inhibited by the presence of molecular oxygen. Such inhibition is typically observed, for example, in curable compositions that are curable by a radical mechanism. The desired dead zone thickness can be maintained by selecting various control parameters, such as the photon flux and the optical and cure properties of the curable composition. The CLIP process proceeds by projecting a continuous sequence of actinic (e.g., UV) images (which may be generated, for example, by a digital light processing image processing device) through an oxygen-permeable, actinic (e.g., UV)-transparent window below a bath of curable composition maintained in liquid form. The liquid interface below the advancing (growing) article is maintained by the dead zone created above the window. The curing article can be continuously withdrawn from the bath of curable composition above the dead zone and replenished by pumping additional amounts of curable composition into the bath to compensate for the amount of curable composition that is being hardened and incorporated into the growing article.

[0106] Aspects of the present invention Exemplary, non-limiting embodiments of the present invention can be summarized as follows: Aspect 1: A (meth)acrylate-functionalized oligomer comprising: a) an oligomer backbone comprised of a first segment and a second segment; and b) (meth)acrylate-functionalized end groups, wherein the first segment, the second segment, and the (meth)acrylate-functionalized end groups are connected by linkages derived from a polyisocyanate; the first segment is a residue of a first segment precursor comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups and having a number average molecular weight of at least 250 Daltons; the second segment is a residue of a second segment precursor different from the first segment precursor, comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups and having a number average molecular weight of at least 250 Daltons; and the Hansen Solubility Parameter Distance Relative Energy Difference between the first segment and the second segment is at least about 4 and no more than about 9. Aspect 2: The (meth)acrylate-functionalized oligomer of Aspect 1, wherein the Hansen Solubility Parameter Distance Relative Energy Difference between the first segment and the second segment is at least 4 and not more than 8.5. Aspect 3: The (meth)acrylate-functionalized oligomer of Aspect 1 or 2, wherein the (meth)acrylate-functionalized oligomer is liquid or solid at 25°C and when combined with up to 40% by weight / weight of a reactive diluent that is liquid at 25°C forms a composition that is liquid at 25°C. Embodiment 4: The (meth)acrylate-functionalized oligomer of any one of embodiments 1-3, wherein the (meth)acrylate-functionalized oligomer has a number average molecular weight of about 3000 to about 30,000 Daltons. Embodiment 5: The (meth)acrylate-functionalized oligomer of any one of embodiments 1-4, wherein the (meth)acrylate-functionalized end group is a residue of a hydroxyalkyl (meth)acrylate, a thioalkyl (meth)acrylate, or an aminoalkyl (meth)acrylate. Embodiment 6: The (meth)acrylate-functionalized oligomer of any one of embodiments 1-5, wherein the (meth)acrylate-functionalized end group is a residue of hydroxyethyl (meth)acrylate. Embodiment 7: The (meth)acrylate-functionalized oligomer of any one of embodiments 1-6, wherein the polyisocyanate is a diisocyanate. Aspect 8: The (meth)acrylate-functionalized oligomer of any one of Aspects 1 to 7, wherein the polyisocyanate is selected from the group consisting of toluene diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, methylene bis(4-isocyanatocyclohexane), and combinations thereof. Aspect 9: The (meth)acrylate-functionalized oligomer of any one of Aspects 1 to 8, wherein the isocyanate-reactive functional group in one or both of the first segment precursor and the second segment precursor is selected from the group consisting of a hydroxyl group, a thiol group, and an amino group. Embodiment 10: The (meth)acrylate-functionalized oligomer of any one of embodiments 1-9, wherein the first segment precursor and the second segment precursor are independently selected from the group consisting of polymer polyols. Embodiment 11: The (meth)acrylate-functionalized oligomer of any one of embodiments 1 to 10, wherein the first segment precursor and the second segment precursor are independently selected from the group consisting of polyether polyols, polycarbonate polyols, and polyester polyols. Aspect 12: The (meth)acrylate-functionalized oligomer of any one of Aspects 1-11, wherein the first segment precursor and the second segment precursor are independently selected from the group consisting of polypropylene glycol, polytetramethylene oxide glycol, poly(neopentyl glycol adipate) polyol, methylene bis[4-cyclohexyl(2-hydroxy-2-methylethyl)carbamate], and propoxylated neopentyl glycol. Embodiment 13: The (meth)acrylate-functionalized oligomer of any one of embodiments 1 to 12, wherein the first segment precursor and the second segment precursor have different number average molecular weights. Embodiment 14: The (meth)acrylate-functionalized oligomer of any one of embodiments 1-13, wherein the first segment precursor has a number average molecular weight and the second segment precursor has a number average molecular weight that differs from the number average molecular weight of the first segment precursor by at least 1000 Daltons. Embodiment 15: The (meth)acrylate-functionalized oligomer of any one of embodiments 1-14, wherein both the first segment precursor and the second segment precursor each independently have a number average molecular weight of 5000 Daltons or less. Embodiment 16: The (meth)acrylate-functionalized oligomer of any one of embodiments 1 to 15, wherein both the first segment precursor and the second segment precursor each independently have a number average molecular weight of 250 to 5000 Daltons that differ from each other by at least 1000 Daltons. Embodiment 17: The (meth)acrylate-functionalized oligomer of any one of embodiments 1 to 16, wherein the first segment and the second segment are statistically distributed along the oligomer backbone. Embodiment 18: The (meth)acrylate-functionalized oligomer of any one of embodiments 1 to 16, wherein the first segment and the second segment are not statistically distributed along the oligomer backbone. Embodiment 19: The (meth)acrylate-functionalized oligomer of any one of embodiments 1 to 18, wherein the oligomer backbone comprises a plurality of linkages selected from the group consisting of urethane linkages, urea linkages, and thiourethane linkages. Aspect 20: a) the first segment precursor is polypropylene glycol having a number average molecular weight of 1800 to 2200 daltons, and the second segment precursor is poly(neopentyl glycol adipate) having a number average molecular weight of 1800 to 2200 daltons; or b) the first segment precursor is poly(neopentyl glycol adipate) having a number average molecular weight of 400 to 600 daltons, and the second segment precursor is poly(tetramethylene oxide) glycol having a number average molecular weight of 3000 to 4000 daltons; or c) the first segment precursor is poly(tetramethylene oxide) glycol having a number average molecular weight of 550 to 750 daltons, and the second segment precursor is poly(neopentyl glycol adipate) having a number average molecular weight of 1800 to 2200 daltons; A (meth)acrylate-functionalized oligomer according to any one of embodiments 1 to 19. Aspect 21: a) reacting a first segment precursor having a number average molecular weight of at least 250 Daltons, the first segment precursor comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups, with a polyisocyanate to obtain a first isocyanate-terminated intermediate oligomer; b) reacting the first isocyanate-terminated intermediate oligomer with additional polyisocyanate and a second segment precursor having a number average molecular weight of at least 250 Daltons and comprising a plurality of repeat units and a plurality of isocyanate-reactive functional groups to obtain a second isocyanate-terminated intermediate oligomer; c) reacting the second isocyanate-terminated intermediate oligomer with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer; 1. A (meth)acrylate-functionalized oligomer obtained by a process comprising: A (meth)acrylate-functionalized oligomer, wherein the first segment precursor and the second segment precursor have different compositions, and the Hansen solubility parameter distance relative energy difference between the first segment and the second segment is at least 4 and not more than 9. Aspect 22: a) reacting a mixture of a first segment precursor having a number average molecular weight of at least 250 Daltons, comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups, and a second segment precursor having a number average molecular weight of at least 250 Daltons, comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups, with a polyisocyanate to obtain an isocyanate-terminated intermediate oligomer; b) reacting the isocyanate-terminated intermediate oligomer with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer; 1. A (meth)acrylate-functionalized oligomer obtained by a process comprising: A (meth)acrylate-functionalized oligomer, wherein the first segment precursor and the second segment precursor have different compositions, and the Hansen solubility parameter distance relative energy difference between the first segment and the second segment is at least 4 and not more than 9. Aspect 23: A method of making a (meth)acrylate-functionalized oligomer, comprising: a) reacting a first segment precursor having a number average molecular weight of at least 250 Daltons and comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups with a polyisocyanate to obtain a first isocyanate-terminated intermediate oligomer; b) reacting the first isocyanate-terminated intermediate oligomer with additional polyisocyanate and a second segment precursor having a number average molecular weight of at least 250 Daltons and comprising a plurality of repeat units and a plurality of isocyanate-reactive functional groups to obtain a second isocyanate-terminated intermediate oligomer; c) reacting the second isocyanate-terminated intermediate oligomer with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer; wherein the first segment precursor and the second segment precursor are compositionally different from each other, and the Hansen Solubility Parameter Distance Relative Energy Difference between the first segment and the second segment is at least 4 and not more than 9. Aspect 24: A method of making a (meth)acrylate-functionalized oligomer, comprising: a) reacting a mixture of a first segment precursor having a number average molecular weight of at least 250 Daltons, the first segment precursor comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups, and a second segment precursor having a number average molecular weight of at least 250 Daltons, the second segment precursor comprising a plurality of repeating units and a plurality of isocyanate-reactive functional groups, with a polyisocyanate to obtain an isocyanate-terminated intermediate oligomer; c) reacting the isocyanate-terminated intermediate oligomer with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer; wherein the first segment precursor and the second segment precursor are compositionally different from each other, and the Hansen Solubility Parameter Distance Relative Energy Difference between the first segment and the second segment is at least 4 and not more than 9. Embodiment 25: A curable composition comprising at least one (meth)acrylate-functionalized oligomer according to any one of embodiments 1-20 and at least one additional component other than the (meth)acrylate-functionalized oligomer according to any one of embodiments 1-20. Embodiment 26: A cured composition obtained by curing a curable composition comprising at least one (meth)acrylate-functionalized oligomer according to any one of embodiments 1-20. Embodiment 27: An article comprising the cured composition of embodiment 26. Embodiment 28: A method of making a cured composition, comprising exposing a curable composition comprised of at least one (meth)acrylate-functionalized oligomer according to any one of embodiments 1 to 20 to actinic radiation in an amount effective to cure the at least one (meth)acrylate-functionalized oligomer.

[0107] While embodiments have been described herein in a manner that enables a clear and concise specification to be written, it is intended and recognized that the embodiments may be combined or separated in various ways without departing from the invention. For example, it is recognized that all preferred features described herein are applicable to all aspects of the invention described herein.

[0108] In some embodiments, the invention herein may be construed to exclude any element or process step that does not materially affect the basic and novel characteristics of the methods and compositions described herein. Moreover, in some embodiments, the invention may be construed to exclude any element or process step not specified herein.

[0109] Although the invention has been illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications in the details can be made, within the scope and range of equivalents of the claims, without departing from the invention. [Example]

[0110] Measurement method In this application, the number-average molecular weight was determined by size exclusion chromatography (SEC) according to OCDE (1996), Test No. 118: Determination of the Number-Average Molecular Weight and the Molecular Weight Distribution of Polymers using Gel Permeation Chromatography, OECD Guidelines for the Testing of Chemicals, Section 1, Editions OCDE, Paris, using the following conditions: Two mixed D columns (ref. 1110-6504) + one 100Å column (ref. 1110-6520) + one 50Å column (ref. 1110-6515), (7.8 mm x 300 mm), supplied by Agilent, with a cross-linked polystyrene-divinylbenzene (PS-DVB) gel stationary phase. Mobile phase (THF) flow rate: 1 ml / min Column temperature: 40℃ Detector: Refractive Index (RI) Calibration: Polystyrene standards (Mw: 483.400, 215.000, 113.300, 51.150, 19.540, 10.110, 4.430, 2.930, 1.320, 575, 162 g / mol).

[0111] Example 1 In dry nitrogen 、 In a 1 L resin kettle equipped with a mechanical stirrer, dry nitrogen and air sparge lines, and a dropping funnel, preheated poly(tetramethylene oxide) diol (M n 648.36 g of bismuth octanoate (M = 3500 Da) is added, followed by 1.5 g of BHT and 0.50 g of bismuth octanoate in octanoic acid (approximately 25 wt / wt% Bi). Tolylene diisocyanate (126.55 g of a mixture of 2,4- and 2,6-isomers (approximately 80 / 20)) is added via addition funnel over 90 minutes, and the mixture is allowed to exotherm to 75-85°C. Once all the free polyol is consumed, the reaction temperature is set to 85°C and poly(neopentyl adipate) (M) preheated to 70°C is added. n 181.61 g of 2-hydroxyethyl acrylate (=500 Da) is charged via addition funnel over 15 minutes. The reaction is held at 85°C for 1 hour and the nitrogen sparge is replaced with a dry air sparge. After venting for 10 minutes, 232.4 g of 2-hydroxyethyl acrylate is added and the reaction is held at temperature for an additional 60 minutes before being discharged to give the oligomer as a cloudy, colorless to slightly yellow liquid.

[0112] Example 2 A 1 L resin kettle equipped with a mechanical stirrer and nitrogen inlet is charged with 17.15 g of tricyclodecane dimethanol (preheated to 90°C), 114.12 g of caprolactone, 288.26 g of rac-lactide, 2.5 g of BHT, and 1.0 g of bismuth octanoate dissolved in octanoic acid. The mixture is heated to 95-105°C with vigorous stirring under a nitrogen sparge and held for typically 14-16 hours until all of the lactone has been consumed as determined by HPLC. The resulting polyester diol is held at 100°C and added to a 3 L resin kettle configured as described in Example 1, along with polyethylene oxide diol and poly(propylene oxide) diol (nominal M each). n Charge 1014.20 g of a 1:1 (mol:mol) mixture of 1,3-bis(isocyanatomethyl)cyclohexane (H2O3 = 1000), 500 g of isobornyl methacrylate, and 0.5 g of bismuth octanoate in octanoic acid. The mixture is sparged with nitrogen and heated to 60°C with stirring. To this mixture, 518.40 g of 1,3-bis-(isocyanatomethyl)cyclohexane is fed via addition funnel over 90 minutes. When the isocyanate level drops to 50% of its initial value (as determined by FT-IR spectroscopy, titration, or other suitable analytical technique), the mixture is heated to 95°C and the polyester diol from the first kettle is transferred to the addition funnel of the second kettle and charged to the isocyanate-terminated prepolymer over 3 hours. When the reaction between the polyester polyol and the isocyanate-terminated prepolymer is complete (as determined by isocyanate consumption), the nitrogen sparge is replaced with a dry air sparge, the mixture is cooled to 85°C, and 174.78 g of 2-hydroxyethyl methacrylate is added via addition funnel and allowed to react, as in Example 1. The product is obtained as a highly viscous, colorless, cloudy liquid upon discharge.

[0113] Example 3 The method of Example 1 is repeated, except that poly(tetramethylene oxide) diol (M n = 3500 Da) was mixed with an equimolar amount of poly(neopentyl adipate) diol (M n = 2000 g / mol) and replaced by poly(neopentyl adipate) diol (M n= 500 Da) is replaced by an equimolar amount of poly(tetramethylene oxide) diol. The product is obtained as a cloudy, colorless to pale yellow, semi-solid at room temperature.

[0114] (Examples 4 and 5 and Comparative Examples 6 and 7) The oligomer of Example 1 (Example 4), the oligomer of Example 3 (Example 5), polyester urethane acrylate CN9783 (Comparative Example 6) (commercially available from Sartomer), or polyester urethane acrylate CN9782 (Comparative Example 7) (commercially available from Sartomer) (25 wt%) is blended with cyclic trimethylolpropane formal acrylate (55 wt%, commercially available from Sartomer as SR531), phenyl glycidyl ether acrylate (19.5 wt%, commercially available from Sartomer as CN131), and diphenyl(1,3,5-trimethylbenzoyl)phosphine oxide (0.5 wt%).

[0115] The mechanical properties of these formulations in the cured form are shown in Figure 1 and Table 1. In these formulations, the oligomer of Example 1 simultaneously exhibits increased tensile strength, elongation, and energy to break compared to structurally related high molecular weight non-segmented urethane acrylate oligomers.

[0116] [Table 1]

[0117] Example 8 In a 1 L resin kettle equipped with a mechanical stirrer, dry nitrogen and air sparge lines, and a dropping funnel, poly(propylene glycol) diol (M n236.6 g of bismuth octanoate (M = 2000 Da) is charged, followed by 0.5 g of BHT, 0.5 g of triphenyl phosphite, and 0.50 g of bismuth octanoate in octanoic acid (approximately 25 wt / wt% Bi). Isophorone diisocyanate (108.85 g) is charged via addition funnel over 90 minutes, and the mixture is allowed to exotherm. Once all the free polyol is consumed, the reaction temperature is set to 85°C and poly(neopentyl adipate) (M) preheated to 70°C is added. n 124.9 g of 2-hydroxyethyl acrylate (=500 Da) is charged via addition funnel over 15 minutes. The reaction is held at 85°C for 2.5 hours and the nitrogen sparge is replaced with a dry air sparge. After 10 minutes of aeration, 28.45 g of 2-hydroxyethyl acrylate is added and the reaction mixture is held at temperature for an additional 60 minutes before being discharged to give the oligomer as a cloudy, colorless to slightly yellow liquid.

[0118] (Examples 9 and 10) The oligomer of Example 3 (28.5 wt%) was formulated in combination with hydroxyethyl acrylate (28.5 wt%), cyclic trimethylolpropane formal acrylate (38 wt%), and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (5 wt%) (referred to as Example 9). The oligomer of Example 4 was formulated with hydroxyethyl acrylate (28.5 wt%), phenyl glycidyl ether acrylate (38 wt%, commercially available from Sartomer as CN131), and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (5 wt%) as a photoinitiator (referred to as Example 10). Adhesion data for these compositions can be found in Figure 2 and Table 2.

[0119] [Table 2]

[0120] [Table 3]

Claims

1. a) an oligomer backbone composed of a first segment A and a second segment B; and b) a (meth)acrylate-functionalized end group [Acry]; The first segment A, the second segment B, and the (meth)acrylate-functionalized end group [Acry] are connected by a linking moiety X derived from a diisocyanate; the first segment A is a residue of a first segment precursor selected from the group consisting of polyether diols and polyester diols and having a number average molecular weight of at least 250 Daltons; The second segment B is a residue of a second segment precursor different from the first segment precursor, selected from the group consisting of polyether diols and polyester diols, and having a number average molecular weight of at least 250 daltons; The Hansen solubility parameter distance relative energy difference between the first segment A and the second segment B is at least 4 and not more than 9; The (meth)acrylate-functionalized oligomer has a "segmented" oligomer structure in which a first segment A is connected by a linkage X to form a cluster, a second segment B is also connected by a linkage X to form a cluster, both ends of the cluster of the first segment A are connected to one end of the cluster of the second segment B by a linkage X, and the other end of the cluster of the second segment B is connected to a (meth)acrylate-functionalized end group [Acry] by a linkage X.

2. 10. The (meth)acrylate-functionalized oligomer of claim 1, wherein the (meth)acrylate-functionalized oligomer is a liquid at 25°C or a solid at 25°C and when combined with up to 40% on a wt / wt basis of a reactive diluent that is a liquid at 25°C forms a composition that is a liquid at 25°C.

3. 3. The (meth)acrylate-functionalized oligomer of claim 1 or 2, having a number average molecular weight of 3000 to 30,000 Daltons.

4. 4. The (meth)acrylate-functionalized oligomer according to claim 1, wherein the (meth)acrylate-functionalized end group is a residue of a hydroxyalkyl (meth)acrylate, a thioalkyl (meth)acrylate, or an aminoalkyl (meth)acrylate.

5. 5. The (meth)acrylate-functionalized oligomer of claim 1, wherein the first segment precursor and the second segment precursor are independently selected from the group consisting of polypropylene glycol, polytetramethylene oxide glycol, poly(neopentyl glycol adipate) polyol, methylene bis[4-cyclohexyl(2-hydroxy-2-methylethyl)carbamate], and propoxylated neopentyl glycol.

6. 6. The (meth)acrylate-functionalized oligomer of claim 1, wherein the first segment precursor has a number average molecular weight and the second segment precursor has a number average molecular weight that differs from the number average molecular weight of the first segment precursor by at least 1000 Daltons.

7. a) the first segment precursor is polypropylene glycol having a number average molecular weight of 1800 to 2200 daltons and the second segment precursor is poly(neopentyl glycol adipate) having a number average molecular weight of 1800 to 2200 daltons; or b) the first segment precursor is poly(neopentyl glycol adipate) having a number average molecular weight of 400 to 600 daltons and the second segment precursor is poly(tetramethylene oxide) glycol having a number average molecular weight of 3000 to 4000 daltons; or c) the first segment precursor is poly(tetramethylene oxide) glycol having a number average molecular weight of 550 to 750 daltons, and the second segment precursor is poly(neopentyl glycol adipate) having a number average molecular weight of 1800 to 2200 daltons; 7. The (meth)acrylate-functionalized oligomer according to any one of claims 1 to 6.

8. 8. A method for making the (meth)acrylate-functionalized oligomer of any one of claims 1 to 7, comprising: a) reacting a first segment precursor having a number average molecular weight of at least 250 Daltons and selected from the group consisting of polyether diols and polyester diols with a diisocyanate to obtain a first isocyanate-terminated intermediate oligomer; b) reacting the first isocyanate-terminated intermediate oligomer with an additional diisocyanate and a second segment precursor having a number average molecular weight of at least 250 Daltons and selected from the group consisting of polyether diols and polyester diols to obtain a second isocyanate-terminated intermediate oligomer; c) reacting the second isocyanate-terminated intermediate oligomer with a (meth)acrylate compound comprising an isocyanate-reactive functional group and at least one (meth)acrylate functional group to obtain a (meth)acrylate-functionalized oligomer; wherein the first segment precursor and the second segment precursor have different compositions, and the Hansen Solubility Parameter Distance Relative Energy Difference between the first segment and the second segment is at least 4 and not more than 9.

9. 8. A curable composition comprising at least one (meth)acrylate-functionalized oligomer according to any one of claims 1 to 7 and at least one additional component other than the (meth)acrylate-functionalized oligomer according to any one of claims 1 to 7.

10. A cured composition obtained by curing a curable composition comprising at least one (meth)acrylate-functionalized oligomer according to any one of claims 1 to 7.

11. 11. An article comprising the cured composition of claim 10.

12. 10. A method of making a cured composition, comprising exposing a curable composition comprised of at least one (meth)acrylate-functionalized oligomer according to any one of claims 1 to 7 to actinic radiation in an amount effective to cure the at least one (meth)acrylate-functionalized oligomer.

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