Photocurable composition

Abstract

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides photocurable compositions that offer a balance of fast cure characteristics and excellent deep cure when exposed to radiation in the electromagnetic spectrum.

Description

[Technical field]

[0001] The present invention relates to photocurable compositions that have a balance of fast cure properties and excellent deep cure when exposed to radiation in the electromagnetic spectrum. [Background technology]

[0002] There are many photocurable adhesive compositions available, most of which are targeted at medical device assembly applications. Many are marketed on the basis of their physical properties, such as good tack-free cure time, good fixture time, good tensile strength, etc. Noticeably absent from this list is a deep cure.

[0003] Deep cure refers to the ability of an applied light-curable adhesive sample to react such that the reacted adhesive does not flow in the "Z" direction. Deep cure is a difficult physical property to achieve in light-curable adhesives.

[0004] U.S. Patent No. 6,080,450 (Kantor) relates to a polymerizable liquid formulation that cures with a combination of ultraviolet and visible light to a fully cured solid deposit that exhibits a bright fluorescent response, the formulation comprising a free radically polymerizable liquid composition; about 0.02-1.0% by weight of the formulation of a fluorescent agent, the fluorescent agent fluorescing at wavelengths above 350 nm and including at least a portion of the visible region of the spectrum; and 0.15-1.0% by weight of the formulation of a catalyst system that responds to actinic radiation in a radiation band that encompasses a range of at least up to 410 nm and includes at least a portion of the visible spectral region and at least a portion of the ultraviolet spectral region to generate free radicals, thereby effecting polymerization of the polymerizable liquid composition, the formulation being substantially free of non-reactive solvents.

[0005] The focus of U.S. Pat. No. 6,080,450 is to provide polymerizable compositions that are curable by actinic radiation and contain a light-emitting agent, which can enhance the light-emitting effect while maintaining or improving the curing properties of the composition.

[0006] Nonetheless, improved deep cure in photocurable compositions is desirable. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 6,080,450 Summary of the Invention [Means for solving the problem]

[0008] In this specification, (a) a (meth)acrylate component; (b) a (meth)acrylate-functionalized resin component; and (c) an initiator component comprising a combination of a blue fluorescent compound and a coinitiator; The photocurable composition includes the fluorescent compound, which should absorb energy at wavelengths less than about 400 nm (e.g., about 180 nm) and emit (or fluoresce) energy at wavelengths greater than about 400 nm (e.g., up to about 600 nm). The fluorescent compound preferably includes 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole).

[0009] For example, intensity 100mW / cm 2 , preferably 200mW / cm 2 Upon exposure to a radiation source emitting radiation at a wavelength of 405 nm for at least about 30 seconds, the composition cures into a cured composition that exhibits a depth of cure throughout the volume of the composition.

[0010] In one embodiment, the present invention provides a photocurable composition comprising: (a) isobornyl (meth)acrylate in an amount of about 5 to about 50 weight percent, e.g., about 15 to about 40 weight percent, based on the total weight of the composition; (b) N,N-dimethylacrylamide in an amount of about 20 to about 30 weight percent, based on the total weight of the composition; (c) a (meth)acrylate-functionalized resin in an amount of about 15 to about 50 weight percent, e.g., about 25 to about 35 weight percent, based on the total weight of the composition; and (d) a combination of 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole) and benzoyl peroxide as initiator components.

[0011] In another aspect, the present invention provides a method for curing a photocurable composition comprising applying a composition of the present invention to at least a first substrate and exposing the composition to radiation in the electromagnetic spectrum, such as that emitted by a light emitting diode ("LED"), to cure the cured composition in depth.

[0012] Surprisingly, it has been found that an initiator component comprising a combination of a blue fluorescent compound and a coinitiator provides a depth of cure to the composition as it cures upon exposure to radiation in the electromagnetic spectrum, such as that emitted by an LED. More specifically, the initiator component is a combination of a fluorescent compound and a coinitiator. Desirably, the fluorescent compound comprises 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole). And importantly, the initiator component does not include a phosphine oxide photoinitiator.

[0013] The components of the compositions of the present invention, including at least the urethane (meth)acrylate resin component, the (meth)acrylate component, and the initiator component, may be mixed in any order for a time sufficient to ensure proper dissolution or dispersion. The compositions may be cured, if desired, by radiation in the electromagnetic spectrum, such as UV, visible, UV / visible, particularly 405 nm radiation, emitted from LED lamps such as Loctite brand CureJet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] As noted above, the present invention in one aspect comprises: (a) a (meth)acrylate component; (b) a (meth)acrylate-functionalized resin component; and (c) an initiator component comprising a combination of a blue fluorescent compound and a coinitiator; The photocurable composition includes a fluorescent compound that absorbs energy at wavelengths less than about 400 nm (e.g., about 180 nm) and emits energy (or fluoresces) at wavelengths greater than about 400 nm (e.g., up to about 600 nm). Desirably, the fluorescent compound includes 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole). Additionally, the composition of the present invention does not include a phosphine oxide photoinitiator.

[0015] For example, 100 mW / cm for at least about 30 seconds. 2 , e.g. 200mW / cm 2 When exposed to a radiation source emitting radiation at a wavelength of 405 nm with an intensity of 1000 nm, the composition cures into a cured composition that exhibits a depth of cure throughout the volume of the composition (also referred to as deep or volumetric cure).

[0016] In one embodiment, the present invention provides a photocurable composition comprising: (a) isobornyl (meth)acrylate in an amount of about 5% to about 50% by weight, e.g., about 15% to about 40% by weight, based on the total weight of the composition; (b) N,N-dimethylacrylamide in an amount of about 20% to about 30% by weight, based on the total weight of the composition; (c) a (meth)acrylate-functionalized resin in an amount of about 15% to about 50% by weight, e.g., about 25% to about 35% by weight, based on the total weight of the composition; and (d) a combination of 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole) and benzoyl peroxide as initiator components.

[0017] In another aspect, the present invention provides a method of curing a photocurable composition comprising applying a composition of the present invention to at least a first substrate, exposing the composition to radiation in the electromagnetic spectrum, such as that emitted from a light emitting diode ("LED"), and curing the composition through the cure depth or through the volume of the composition.

[0018] Surprisingly, it has been found that an initiator component comprising a combination of a blue fluorescent compound and a coinitiator provides a depth of cure to the composition as the composition cures when exposed to radiation in the electromagnetic spectrum, such as that emitted by an LED. More specifically, the initiator component is a combination of 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole) as the blue fluorescent compound and benzoyl peroxide as the coinitiator. Typically, photocurable compositions form a skin-over layer on the surface of the composition and provide little or no deep cure without a secondary cure mechanism, such as moisture cure or anaerobic cure. However, the compositions of the present invention exhibit a depth of cure throughout the volume of the composition when exposed to radiation in the electromagnetic spectrum.

[0019] The (meth)acrylate component may include a number of (meth)acrylate monomers, some of which are aromatic, others aliphatic, and still others cycloaliphatic. Examples of such (meth)acrylate monomers include polyethylene glycol di(meth)acrylate, tetrahydrofuran (meth)acrylate and di(meth)acrylate, hydroxypropyl (meth)acrylate ("HPMA"), hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate ("TMPTMA"), diethylene glycol dimethacrylate, triethylene glycol dimethacrylate ("TRIEGMA"), benzyl methacrylate, tetraethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, di-(ethylene glycol dimethacrylate), ... and di- or trifunctional (meth)acrylates such as bisphenol-A mono- and di(meth)acrylates, such as ethoxylated bisphenol-A (meth)acrylate ("EBIPMA"), and bisphenol-F mono- and di(meth)acrylates, such as ethoxylated bisphenol-F (meth)acrylate.

[0020] The (meth)acrylate component should be present in an amount of from about 25% to about 80% by weight, for example from about 55% to about 65% by weight, based on the total weight of the composition.

[0021] Particularly desirable (meth)acrylate monomers include isobornyl (meth)acrylate and N,N-dimethylacrylamide, which may be used in combination.

[0022] When used in combination, (a) isobornyl (meth)acrylate should be present in an amount of about 5% to about 50% by weight, for example about 15% to about 40% by weight, based on the total weight of the composition, and (b) N,N-dimethylacrylamide should be present in an amount of about 20% to about 30% by weight, based on the total weight of the composition.

[0023] The (meth)acrylate-functionalized resin component includes oligomers having a number average molecular weight of about 500 to about 100,000 Mn, for example, about 2,500 to about 25,000 Mn, particularly oligomers having urethane bonds. The number average molecular weight can be measured, for example, by gel permeation chromatography.

[0024] In one embodiment, the composition of the present invention includes a (meth)acrylate-functionalized resin component present in an amount of about 15% to about 50% by weight, e.g., about 25% to about 35% by weight, based on the total weight of the composition.

[0025] Examples of (meth)acrylate-functionalized resins are (meth)acrylate-functionalized urethanes, (meth)acrylate-functionalized polyesters, and poly(isobutylene) di(meth)acrylates.

[0026] Suitable (meth)acrylate-functionalized urethanes (or urethane (meth)acrylate resins) as the (meth)acrylate-functionalized resin component include, for example, those disclosed in U.S. Pat. Nos. 4,018,851, 4,295,909, and 4,309,526 to Bassey, and U.S. Pat. Nos. Re. 33,211, 4,751,273, 4,775,732, 5,019,636, and 5,139,872 to Lapin et al.

[0027] Other examples of such (meth)acrylate functionalized urethanes include tetramethylene glycol urethane acrylate oligomers and propylene glycol urethane acrylate oligomers.

[0028] Yet another (meth)acrylate functionalized urethane is a monofunctional urethane acrylate oligomer such as polypropylene terminated with 4,4'-ethylenebis(cyclohexylisocyanate) and capped with 2-hydroxyethyl acrylate and 1-docosanol.

[0029] These include, for example, difunctional urethane methacrylate oligomers such as polytetramethylene glycol ether terminated with toluene-2,4-diisocyanate and capped with 2-hydroxyethyl methacrylate; polytetramethylene glycol ether terminated with isophorone diisocyanate and capped with 2-hydroxyethyl methacrylate; polytetramethylene glycol ether terminated with 4,4'-methylenebis(cyclohexylisocyanate) and capped with 2-hydroxyethyl methacrylate; and polypropylene glycol terminated with tolylene-2,4-diisocyanate and capped with 2-hydroxyethyl methacrylate.

[0030] The (meth)acrylate-functionalized resin component may be a multi- (e.g., di- or tri-) functional urethane acrylate oligomer, more preferably an aliphatic polyether urethane acrylate. An example of a suitable (meth)acrylate-functionalized resin component is Bomar BR-582-E8 (commercially available from Dymax, Inc., Torrington, Connecticut), which is described as an aliphatic urethane acrylate oligomer having a polyether backbone. Bomar BR-582-E8 is listed in the table below.

[0031] Dymax also markets a series of other (meth)acrylate-functionalized urethanes with functionalities ranging from about 1 to about 3 and elongations greater than about 50. One such Dymax (meth)acrylate-functionalized urethane is a trifunctional urethane acrylate oligomer, more specifically an aliphatic polyether urethane triacrylate known as BR-990.

[0032] (Meth)acrylate-functionalized urethanes include those based on polyesters or polyethers, reacted with aromatic, aliphatic, or cycloaliphatic diisocyanates, and capped with hydroxyacrylates.

[0033] For example, difunctional urethane acrylate oligomers, such as polyester of hexanedioic acid and diethylene glycol terminated with isophorone diisocyanate and capped with 2-hydroxyethyl acrylate (CAS 72121-94-9); polypropylene glycol terminated with tolylene-2,6-diisocyanate and capped with 2-hydroxyethyl acrylate (CAS 37302-70-8); polyester of hexanedioic acid and diethylene glycol terminated with 4,4′-methylenebis(cyclohexylisocyanate) and capped with 2-hydroxyethyl acrylate (CAS 69011-33-2); tolylene- Polyesters of hexanedioic acid, 1,2-ethanediol, and 1,2-propanediol terminated with 2,4-diisocyanate and capped with 2-hydroxyethyl acrylate (CAS 69011-31-0); polyesters of hexanedioic acid, 1,2-ethanediol, and 1,2-propanediol terminated with 4,4'-methylenebis(cyclohexylisocyanate) and capped with 2-hydroxyethyl acrylate (CAS 69011-32-1); and polytetramethylene glycol ether terminated with 4,4'-methylenebis(cyclohexylisocyanate) and capped with 2-hydroxyethyl acrylate.

[0034] Commercially available (meth)acrylate-functionalized urethane resins from Dymax that may be useful include BR-930D [described by the manufacturer as a flexible, weather-resistant polyether urethane acrylate with a nominal viscosity of 7,700 at 60° C. and a DMA Tg of 95° C. The manufacturer advertises that BR-930D has the following characteristics that make it ideal for certain applications as a 3D printing resin: high heat distortion temperature, excellent toughness and impact resistance, improved weather resistance and reduced skin irritation]; BR7432G130 [described by the manufacturer as a flexible, weather-resistant polyester urethane acrylate with a nominal viscosity of 80,000 at 25° C. and a DMA Tg of 28° C.]. The manufacturer advertises BR-7432G130 as having the following characteristics for specific applications: toughness, high tensile strength, improved impact resistance, adheres to polymeric films, elastomeric; BR-3741AJ [described by the manufacturer as a flexible, weather-resistant polyether urethane acrylate with a nominal viscosity of 25,000 at 60°C and a Tg by DMA of -50°C. The manufacturer advertises BR-3741AJ as having the following characteristics for specific applications: enhances softness and flexibility, improves optical clarity, non-yellowing, improves adhesion, adheres to a wide range of substrates, exhibits hydrolytic stability, is resistant to oils and chemicals, and is ideal for PSAs].

[0035] Thus, the (meth)acrylate functionalized urethane may be selected from a variety of materials, some of which are commercially available from Dymax Corporation and are set forth in the table below with their particular salient characteristics.

[0036] [Table 1]

[0037] [Table 2]

[0038] [Table 3]

[0039] [Table 4]

[0040] As an example, BR-345 (meth)acrylate functionalized urethane may be prepared according to the following reaction scheme:

[0041] [ka]

[0042] Another example of a useful (meth)acrylate functionalized urethane is a block resin described as polymer of 4,4-(1-methylethylidene)bis-cyclohexanol with 1,3-dicyanatomethylbenzene and tetrahydrofuran, propylene glycol monomer (CAS number 2243075-64-9), prepared in a sequence of steps by reacting propylene glycol monomer with a dicarboxylic acid to form a polyester diol, followed by reaction with toluene diisocyanate, and finally capping with hydroxypropyl (meth)acrylate.

[0043] Yet another example of a useful (meth)acrylate-functionalized urethane is a block resin made from a saturated polyester diol (such as that sold under the trade name Desmophen S-1011-35) and dicyclohexylmethane-4,4'-diisocyanate (sold commercially as Desmodur W), capped with 2-hydroxyethyl acrylate, the block resin being diluted with IBOA.

[0044] Resins may be used in which TDI-HBPA or IPDI-HMTD is attached via urethane linkages to a central segment of Polymeg 2000 (a polytetramethylene ether glycol produced by polymerizing tetrahydrofuran to form a linear diol with a repeating backbone of tetramethylene units linked by ether linkages and capped with primary hydroxyl units) and capped with TDI-HPMA or IPDI-HEMA. Resins made from hydroxy-functionalized polyethers, polyesters (commercially available as Kuraray Polyol P-2010) and TDI may also be used with hydroxypropyl (meth)acrylate and isobornyl (meth)acrylate. Similarly, resins made from polyTHF (weight average molecular weight ("Mw") 2,000) and TDI may also be used with HBPA, hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate and isobornyl (meth)acrylate.

[0045] In some cases, it may be desirable to have hydrophobic (meth)acrylate-functionalized urethanes having a Mw of 35,000 to 60,000 g / mol as measured by gel permeation chromatography ("GPC"), as described in U.S. Pat. No. 10,745,590. If the Mw is within this range, the cured product may also exhibit strong cohesion and high elongation. It is desirable for the hydrophobic (meth)acrylate-functionalized urethanes to have a functionality of the (meth)acrylate groups of 2 or less. If the functionality of the (meth)acrylate groups is within this range, the cured product may also exhibit high elongation. These hydrophobic (meth)acrylate-functionalized urethanes should have a glass transition temperature value ("Tg") of -60°C to 20°C as measured by differential scanning calorimetry ("DSC").

[0046] The hydrophobic (meth)acrylate functionalized urethane may be selected from aliphatic urethane (meth)acrylates, aromatic urethane (meth)acrylates, and mixtures thereof, such as polybutadiene-based urethane (meth)acrylates, polyisobutylene-based urethane (meth)acrylates, polyisoprene-based urethane (meth)acrylates, polybutyl rubber-based urethane (meth)acrylates, and mixtures thereof. Suitable commercially available hydrophobic urethane (meth)acrylates include UT-4462 and UV36301B90 from Nippon Synthetic Chemical Industry Co., Ltd., CN9014 from Sartomer Corporation, and SUO-H8628 from SHIIN-A T&C Corporation.

[0047] (Meth)acrylate functionalized urethanes may also include polyurethane block copolymers having a backbone of alternating hard and soft segments and at least two ends, each of which may be terminated with a vinyl ether, alkenyl ether, or (meth)acrylate group. Such polyurethane block copolymers may be represented by the general formula:

[0048] [ka] where A is a hard segment, such as the reaction product of a polyisocyanate with an aromatic, heterocyclic, or alicyclic polyol; B is a divalent soft segment; X is a p-valent soft segment; For example, B and X are divalent and polyvalent groups, respectively, derived from polyether polyols, polyester polyols, or hydrogenated hydrocarbon elastomers, such as polybutadiene; D is a vinyl ether or (meth)acrylate group, for example the vinyl ether is derived from a hydroxy-functional vinyl ether such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, cyclohexanedimethanol monovinyl ether, diethylene glycol monovinyl ether, 1,6-hexanediol monovinyl ether and 3-aminopropyl vinyl ether, or the vinyl ether end group is derived from an amino-functional vinyl ether, in which case a vinyl ether urea capped polyurethane may be obtained; p is 0 to 10; q is 2 to 6.

[0049] Another example of (meth)acrylate-functionalized urethane is one in which at least a portion of the polyurethane backbone contains urethane bonds formed from isophorane diisocyanate.For example, such (meth)acrylate-functionalized urethane is made from alkylene glycol (such as polypropylene glycol), isophorane diisocyanate, and hydroxyalkyl (meth)acrylate (such as hydroxyethyl acrylate).Other examples include polyester of hexanedioic acid, diethylene glycol, terminated with isophorone diisocyanate and capped with 2-hydroxyethyl acrylate; polytetramethylene glycol ether terminated with isophorone diisocyanate and capped with 2-hydroxyethyl methacrylate; and hydroxy-terminated polybutadiene terminated with isophorone diisocyanate and capped with 2-hydroxyethyl acrylate.

[0050] The initiator component includes a combination of a blue fluorescent compound and a coinitiator.

[0051] The initiator component should be present in an amount of from about 0.01% to about 5% by weight, such as from about 0.5% to about 4% by weight, based on the total weight of the composition.

[0052] The blue fluorescent compound may be selected from many known compounds.

[0053] A blue fluorescent compound should absorb energy at wavelengths less than about 400 nm (eg, around 180 nm) and emit (or fluoresce) energy at wavelengths greater than about 400 nm (eg, up to about 600 nm).

[0054] The blue fluorescent compounds are also considered optical brighteners, including benzoxazole and its derivatives, bisbenzoxazole, bisbenzoxazolylstilbene, bisbenzoxazolylthiophene, thiophenediylbenzoxazole, and / or 2,5-thiophenediylbis-(5-tert-butyl-1,3-benzoxazole).

[0055] Examples of commercially available optical brighteners include BASF's Tinopal OB and Ubitex OB, which absorb ultraviolet light and re-emit visible blue light.

[0056] Other examples of such fluorescent compounds include:

[0057] [ka]

[0058] Additionally, other exemplary fluorescent compounds useful in the present invention include:

[0059] [ka]

[0060] However, preferably the blue fluorescent compound should be 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole).

[0061] The blue fluorescent compound may be present in an amount of from about 0.01% to about 5% by weight, such as from about 0.5% to about 4% by weight, based on the total weight of the composition.

[0062] In some embodiments of the present invention, the amount of the blue fluorescent compound is from 0% to 2% by weight, for example from 0.05% to 1% by weight, desirably from 0.05% to 0.5% by weight, based on the total weight of the photocurable composition.

[0063] The coinitiator can be selected from a number of materials, so long as they act via a free radical mechanism. Desirably, the coinitiator should be benzoyl peroxide.

[0064] The coinitiator may be present in an amount of about 0.01% to about 5% by weight, for example about 0.5% to about 4% by weight, based on the total weight of the composition.

[0065] The compositions of the present invention may include one or more additives, such as colorants, such as pigments or dyes. Carbon black is one such colorant, which may be used in an amount of about 0.0025 to about 5% by weight of the composition, such as about 0.1 to about 1% by weight of the composition. Titanium dioxide is another useful colorant, which may be used in an amount of about 0.01 to about 3% by weight of the composition, such as about 0.1 to about 1% by weight of the composition. Additionally, colorants in the form of dyes or pigments may be used, and may be selected from, for example, red, yellow, blue, green, and purple.

[0066] In one aspect, the present invention provides a method of curing a composition of the present invention comprising applying a composition of the present invention to at least a first substrate and exposing the composition to radiation in the electromagnetic spectrum, such as emitted from an LED light source as described herein.

[0067] At least one substrate should be a plastic material, preferably transparent to UV, visible or UV / visible light. By way of example, the plastic material, preferably transparent to such radiation, can be selected from at least one of polyvinyl chloride, polyethylene, polypropylene, polycarbonate, acrylonitrile butadiene styrene, polyethylene terephthalate, and thermoplastic elastomers.

[0068] At least one of the first and second substrates to be joined using the composition of the present invention can include a tube of: (i) For the transfer (including removal) of medical fluids, including liquids such as electrolytes (e.g. saline or blood) and gases (e.g. oxygen); (ii) Catheters or the like, in a form for insertion into the body, for example for insertion into the vascular system or into a tube such as the urinary tract; (iii) Part of an implantable device; (iv) a cannula to be inserted into a subject, e.g., for connection to an intravenous catheter; (v) For connection to medical equipment such as pumps, including insulin pumps, or hemodialysis machines (vi) For use as a sheath, e.g., to house wires from a medical device. EXAMPLES

[0069] The composition of the present invention can be applied to a 405 nm wavelength LED light source at an intensity of, for example, 100 mW / cm 2 When exposed to radiation in the electromagnetic spectrum at 1000 Hz, it fully cures in approximately 30 seconds.

[0070] First, three commercially available light-curable products were evaluated and specific physical properties were described as a measure of their performance. According to the manufacturer, the commercially available products are Loctite 3341, Loctite 3921, and Loctite 3961.

[0071] Loctite 3341 is a transparent, light yellow, light-curing, universal acrylic instant adhesive suitable for metals and stress-sensitive plastics, with fast cure upon request. Cure depth exceeds 13 mm. Tack-free time is 15 seconds, fixation time is 8 seconds. Shore hardness D27, low viscosity 500 mPa·s. According to the manufacturer, Loctite 3341 contains urethane acrylate oligomer (30-60% by weight), N'N-dimethylacrylamide (10-30% by weight), acrylate ester (10-30% by weight), urethane acrylate oligomer (10-30% by weight), isobornyl acrylate (5-10% by weight), phosphine oxide (1-5% by weight), acrylate ester (1-5% by weight), and 2-hydroxyethyl acrylate (0.1-1% by weight).

[0072] Loctite 3921 is a light-curing acrylic adhesive formulated to provide a flexible bond when joining stress-sensitive plastics. The product has a cure depth of over 13 mm and a fix time of just 3 seconds. According to the manufacturer, Loctite 3921 contains N'N-dimethylacrylamide (10-30% by weight), acrylate monomers (10-30% by weight), and substituted silanes (1-5% by weight).

[0073] Loctite 3961 contains isobornyl acrylate (30-60% by weight), N´N-dimethylacrylamide (10-30% by weight), photoinitiator (1-3% by weight), urethane acrylate oligomer (10-30% by weight), ethylphenyl (2,4,6-trimethylbenzoyl)phosphinate (1-5% by weight), acrylic acid oligomer (1-5% by weight), gamma-glycidoxypropyltrimethoxysilane (1-5% by weight), 2-propenoic acid (1-5% by weight), 2-carboxyethyl ester (1-5% by weight), acrylate ester (1-5% by weight), acrylic acid (1-5% by weight), and 2-hydroxyethyl acrylate (0.1-1% by weight).

[0074] Three grams of each sample were dispensed into aluminum pans and exposed to radiation in the electromagnetic spectrum emitted by a Loctite brand 405 nm CureJet (LED radiation source) at 100 mW / cm 2 The coating was cured at a light intensity of 1000 .mu.m.

[0075] Each of these three commercial products was mixed with 0.5% by weight of Luperox A98 (anhydrous benzoyl peroxide) and these samples (sample numbers 1-3) were dispensed into aluminum dishes and exposed to radiation in the electromagnetic spectrum emitted by a Loctite brand 405 nm cure jet at 100 mW / cm. 2 The coating was cured at a light intensity of 1000 .mu.m.

[0076] Comparing the depth of cure observed for the three commercial samples with the depth of cure observed for each commercial sample plus benzoyl peroxide, sample numbers 1-3, it can be seen that even a 5 second exposure results in a noticeable increase in cure depth, and a steady increase with a 10 second exposure. The observed data is shown in Table 1 below.

[0077] [Table 5]

[0078] The information presented in Table 1 shows that for Samples 1-3, the depth of cure compared to their respective base commercial products is improved with only 5 seconds of exposure to light, and is quite significantly improved after 10 seconds of exposure to light.

[0079] Next, Loctite 3921 was used as a control, and benzoyl peroxide was added at 0.5% by weight to create sample number 4, and 0.1% by weight to create sample number 5. Each of these three samples was dispensed into a beaker and exposed to 100 mW / cm2 radiation in the electromagnetic spectrum emitted by a Loctite brand 405 nm cure jet. 2 The samples were exposed to a light intensity of 10000 for 30 seconds. 20 grams of Loctite 3921 and Sample No. 4 were dispensed, and 30 grams of Sample No. 5 were dispensed. The observed data is shown in Table 2 below.

[0080] [Table 6]

[0081] The information presented in Table 2 shows that after 30 seconds of exposure to radiation in the electromagnetic spectrum, sample numbers 4-5 show an improved depth of cure compared to the base commercial product, Loctite 3921. In fact, the addition of benzoyl peroxide was observed to increase the depth of cure by more than 4-5 times.

[0082] Next, three commercially available light-curable products containing fluorescent compounds were evaluated to demonstrate specific physical properties as a measure of their performance. According to the manufacturers, the commercially available products are Loctite 3041, Loctite 3963, and Loctite 3951.

[0083] Loctite 3041 is designed for joining cannulas to hubs, syringes and lancets.

[0084] Loctite 3963 is a low viscosity light-cure adhesive designed for applications requiring a fast-setting, rigid adhesive. It is ideal for joining a variety of metals and plastics. Loctite 3963 maintains high adhesion to rigid substrates such as stainless steel, polycarbonate, ABS, acrylic, HDPE (if treated), and PP (if treated). Loctite 3963 is suitable for the assembly of disposable medical devices.

[0085] Loctite 3951 is a low viscosity light-curing adhesive designed for applications requiring a fast curing, highly flexible adhesive. It is ideal for bonding plasticized PVC, TPE, and thermoset rubbers. It also maintains high adhesion to rigid substrates such as polycarbonate, ABS, acrylic, HDPE (if treated), and PP (if treated). Loctite 3951 is suitable for the assembly of disposable medical devices.

[0086] Each contains 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole), but in different concentrations. The presence of this compound in each of these three commercially available products used in the assembly of disposable medical devices allows for easy inspection of the location on the parts where they will be joined.

[0087] Additional evaluations were performed moving away from one or more of the commercial samples to a model-based formulation as a control. The model-based formulation was made from IBOA (35 wt%), DMAA (35 wt%), and Bomar BR-582-E8 (30 wt%). Bomar BR-582-E8 is an aliphatic polyether urethane acrylate oligomer that, according to the manufacturer, Dymax, Inc. (Torrington, Connecticut), offers a balance of toughness and flexibility. Dymax highly recommends this oligomer product for use in single-layer flexible coatings on metal and plastic substrates, and it also exhibits abrasion resistance, flexibility, gloss, hydrolytic stability, weatherability, and non-yellowing, making it an excellent choice for impact and flex-resistant coatings. According to Dymax, this oligomer product has a Tg by DMA of 23°C, a nominal viscosity of 60,000 cP at 50°C, and will bond to a variety of substrates, although it will not bond to high-density polyethylene.

[0088] Benzoyl peroxide was added to the model base formulation in an amount of 0.5% by weight. Benzoyl peroxide was also added to the model base formulation in an amount of 0.5% by weight, and a fluorescent compound was also added. In two cases, the fluorescent compound was Tinopal. In the third case, the fluorescent compound was Natmar Scanning Compound SC-25, available from Angstrom Technology, Inc. (Florence, Kentucky). According to the manufacturer, SC-25 is described as one of Angstrom's "world class" organic pigments, an organic pigment that can be used as a dye in toluene, acetone, and alcohol. According to the manufacturer, SC-25 is a combination of 50-60% by weight of an organometallic compound and 40-50% by weight of a phosphoroaryl compound. It has a red UV excitation color and a fluorescent emission at 615 nm. That is, SC-25 absorbs ultraviolet light and re-emits visible red light.

[0089] Tinopal was used in an amount of 0.5% or 1% by weight, and SC-25 was used in an amount of 1% by weight. Thus, four samples, referred to herein as sample numbers 6-9, were prepared.

[0090] Thirty grams of each of these four samples were dispensed into aluminum dishes and exposed to 100 mW / cm of electromagnetic spectrum radiation emitted by a Loctite brand 405 nm cure jet. 2 The samples were exposed to a light intensity of 0.05% for 10 or 30 seconds. The observed data is shown in Table 3 below.

[0091] Sample number 9 is split into two data points, sample number 9a is exposed to radiation in the electromagnetic spectrum for 10 seconds and sample number 9b is exposed to radiation in the electromagnetic spectrum for 30 seconds.

[0092] [Table 7]

[0093] The information shown in Table 3 was obtained by doping a fluorescent compound and irradiating it at 100 mW / cm 24 shows that when exposed to 405 nm radiation for 10 or 30 seconds at a light intensity of 100 nm, Samples Nos. 7 and 9b show significant depth of cure compared to their respective controls, Samples Nos. 6, 8 and 9a.

Claims

1. (a) a (meth)acrylate component; (b) a (meth)acrylate-functionalized resin component; and (c) an initiator component comprising a combination of a blue fluorescent compound and a coinitiator; A photocurable composition comprising: Wavelength 405nm, intensity 100mW / cm ２ 1. A photocurable composition which upon exposure to a radiation source of at least about 30 seconds cures into a cured composition that exhibits a depth of cure throughout the volume of the composition.

2. 10. The composition of claim 1, wherein the blue fluorescent compound absorbs energy at wavelengths less than about 400 nm and emits energy at wavelengths greater than about 400 nm.

3. 10. The composition of claim 1, wherein the blue fluorescent compound absorbs energy at a wavelength of about 180 nm and emits energy at a wavelength of about 600 nm.

4. 2. The composition of claim 1, wherein the blue fluorescent compound comprises 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole).

5. The composition of claim 1 , wherein the coinitiator comprises one or more peroxides.

6. The composition of claim 1 , wherein the coinitiator comprises benzoyl peroxide.

7. The composition of claim 1 , wherein the (meth)acrylate component comprises isobornyl (meth)acrylate and N,N-dimethylacrylamide.

8. The composition of claim 1, wherein the (meth)acrylate component is present in a range of about 25% to about 80% by weight based on the total weight of the composition.

9. The composition of claim 1 , wherein the (meth)acrylate-functionalized resin component comprises one or more of a (meth)acrylate-functionalized urethane, a (meth)acrylate-functionalized polyester, and a poly(isobutylene)di(meth)acrylate.

10. The composition of claim 1, wherein the (meth)acrylate-functionalized resin component has a number average molecular weight of about 500 to about 100,000.

11. The composition of claim 1, wherein the (meth)acrylate-functionalized resin component is present in an amount of about 15 to about 50 weight percent, based on the total weight of the composition.

12. The composition of claim 1, wherein the (meth)acrylate-functionalized resin component is present in an amount of about 25 to about 35 weight percent, based on the total weight of the composition.

13. The composition of claim 7, wherein the (meth)acrylate component, isobornyl (meth)acrylate, is present in an amount of about 5% to about 50% by weight, based on the total weight of the composition.

14. The composition of claim 7, wherein the (meth)acrylate component, isobornyl (meth)acrylate, is present in an amount of about 15% to about 40% by weight, based on the total weight of the composition.

15. 8. The composition of claim 7, wherein the N,N-dimethylacrylamide is present in an amount of about 20% to about 30% by weight based on the total weight of the composition.

16. 2. The composition of claim 1, wherein the initiator component comprises 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole) as a fluorescent compound and benzoyl peroxide as a coinitiator.

17. The composition of claim 1, wherein the initiator component is present in an amount of about 0.01 to about 5 weight percent, based on the total weight of the composition.

18. The composition of claim 1, wherein the fluorescent compound of the initiator component is present in an amount of about 0.5 to about 5 weight percent, based on the total weight of the composition.

19. The composition of claim 1, wherein the coinitiator of the initiator component is present in an amount of about 0.01 to about 3 weight percent, based on the total weight of the composition.

20. 10. The composition of claim 1, wherein the fluorescent compound and coinitiator of the initiator component are present in a weight ratio of about 1:1 to about 500:

1.

21. The composition of claim 1 further comprising a colorant.

22. (a) isobornyl (meth)acrylate in an amount of about 15% to about 40% by weight based on the total weight of the composition; (b) N,N-dimethylacrylamide in an amount of about 20% to about 30% by weight based on the total weight of the composition; (c) a (meth)acrylate-functionalized resin in an amount of about 25% to about 35% by weight based on the total weight of the composition; and (d) a combination of 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole) and benzoyl peroxide as initiator components; The composition of claim 1 comprising:

23. The composition of claim 1, wherein the (meth)acrylate-functionalized resin component is a polymer of 4,4-(1-methylethylidene)bis-cyclohexanol with 1,3-dicyanatomethylbenzene and tetrahydrofuran, propylene glycol monomers.

24. The composition of claim 1 , wherein no phosphine oxide photoinitiator is added.

25. (a) applying a quantity of a composition to at least a first substrate; and (b) The composition is irradiated with a light having a wavelength of 405 nm and an intensity of 100 mW / cm ２ to a radiation source through said quantity of composition to cure said composition; 2. A method for curing the photocurable composition of claim 1 comprising:

26. 26. The method of claim 25, comprising bonding a first substrate to a second substrate, the first substrate and the second substrate each being a part of a medical device, and then, optionally, sterilizing the bonded component created by bonding the first substrate to the second substrate.

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