Redox-curable composition and method for producing the same

Abstract

A redox-curable composition, its manufacturing method, and its use are disclosed. The redox-curable composition is useful as a pre-applied adhesive. The redox-curable composition is solid at room temperature and can be heated for application to a substrate, cooled to form a dry-touch adhesive layer on the substrate, mated with another substrate if desired, and activated by exposure to an anaerobic environment. The composition is particularly suitable for the manufacture of complex products such as cell phones, computers, and circuits.

Description

[Technical Field]

[0001] The present invention relates to curable compositions that can be pre-applied to an article, for example, in the form of a non-moving, substantially non-stick coating. In this way, the article can be conveniently handled, packaged, transported, and stored for extended periods of time, after which the coating can be cured at a selected time. Of particular interest are anaerobically curable curable compositions. Compositions that can be pre-applied to an article in the form of a non-moving, substantially non-stick coating and then anaerobically cured are of particular interest. One end use for such compositions is in bonding components of mobile phones and / or handheld devices. [Background technology]

[0002] Anaerobic curing compositions are generally well known. See R.D. Rich, "Anaerobic Adhesives," in Handbook of Adhesion Technology, vol. 29, pp. 467-79, edited by A. Pizzi and K.L. Mittal, Marcel Dekker, Inc., New York (1994), and references cited therein. Their uses are numerous, and new applications continue to be developed.

[0003] Anaerobic adhesive systems are systems that are stable in the presence of oxygen but polymerize in its absence. Polymerization is initiated by the presence of free radicals, often generated from peroxy compounds. Anaerobic adhesive compositions are well known for their ability to remain in a liquid, non-polymerized state in the presence of oxygen and cure to a solid state upon the exclusion of oxygen.

[0004] Anaerobic adhesive systems often contain resin monomers terminated with polymerizable acrylate esters, such as methacrylate, ethyl acrylate, and chloroacrylate esters [e.g., polyethylene glycol dimethacrylate and urethane-acrylates (e.g., U.S. Pat. No. 3,425,988 (Gorman)], derived according to known urethane chemistry. Other components typically present in anaerobically curable adhesive compositions include initiators, such as organic hydroperoxides, for example, cumene hydroperoxide, tertiary butyl hydroperoxide, etc., accelerators to increase the cure rate of the composition, and stabilizers, such as quinones or hydroquinones, to prevent premature polymerization of the adhesive due to decomposition of the peroxy compounds.

[0005] Desirable cure-inducing compositions for inducing and accelerating anaerobic cure may include one or more of saccharin, toluidines such as N,N-diethyl-p-toluidine ("DE-pT") and N,N-dimethyl-o-toluidine ("DM-oT"), and acetylphenylhydrazine ("APH"), along with maleic acid. See, e.g., U.S. Patent Nos. 3,218,305 (Krieble), 4,180,640 (Melody), 4,287,330 (Rich), and 4,321,349 (Rich).

[0006] Saccharin and APH are used as standard accelerator components in anaerobic adhesive cure systems. In fact, many of the LOCTITE® brand anaerobic adhesive products currently available from Henkel Corporation use either saccharin alone or both.

[0007] Anaerobic curable adhesive compositions also typically include a chelating agent, such as ethylenediaminetetraacetic acid (EDTA), which is used to sequester metal ions.

[0008] The preparation of the anaerobic curable composition containing the anaerobic curable component typically includes a liquid carrier component. Thus, the composition is typically in a liquid form and can be dispensed, for example, by an applicator. In use, the anaerobic curable component is applied to a surface using a suitable applicator to form a layer or coating. In many cases, the anaerobic curable composition is applied as beads, for example, continuous beads, to form a gasket.

[0009] Anaerobic curable materials often remain wet after application until they are exposed to suitable anaerobic conditions for curing. For example, anaerobic curable compositions often include liquid monomers.

[0010] Although the anaerobic curing composition may dry somewhat, for example by evaporation (by drying or by allowing it to dry for a period of time), the material often remains wet and sticky. This leads to potential contamination of anything that comes into contact with the article to which the material is applied, and to unwanted removal of the applied material. The latter problem can compromise the integrity of any bond or seal subsequently formed by the anaerobic curing composition, as an insufficient amount may remain to form the desired bond or seal.

[0011] Of course, if the liquid carrier material itself is a liquid monomer, it will remain liquid until anaerobically cured, and therefore these compositions will remain wet, or at least tacky, until cured, even though they can be applied to a substrate after exposure to anaerobic conditions.

[0012] In the past, additional ingredients such as thickeners have been added to materials to make them less fluid, but because the other ingredients are liquid, the overall composition remains somewhat fluid and / or sticky.

[0013] Dispensing the liquid composition anywhere other than on top of a horizontal surface can result in dripping and dribbling. Many attempts have been made to incorporate substances into liquid anaerobic curing compositions to form non-flowing or at least more viscous adhesives. This is also important in the context of threadlockers. See, for example, U.S. Patent No. 6,451,927.

[0014] U.S. Patent Application Publication No. 2004 / 0228998 relates to a curable film preform composition. It describes a curable preform comprising a curable liquid precursor mixed with a polymer powder such that the resulting preform has a tensile strength of greater than 1 pound per square inch. An exemplary preform film is formed by combining polyethylene glycol dimethacrylate anaerobic adhesive with polymethyl methacrylate having an average particle size of approximately 61 microns, a glass transition temperature of 90°C, and a viscosity of 325 cubic centimeters per gram. Mixing and heating to 82°C for 10 minutes, followed by cooling to 20°C, results in a pourable mixture that yields a stretchy, slightly tacky preform. The curable preform can be formed as a film and cut to the desired shape. Because the composition is tacky, it is not suitable for use in pre-applied applications. It would be desirable to have a dry-touch adhesive composition that can be pre-applied to a part, the part can then be shipped without risk of contamination or premature curing of the adhesive, and then bond the part with the pre-applied dry-touch adhesive to another part when desired.

[0015] U.S. Patent Application Publication No. 2007 / 0021533 relates to an encapsulated curable adhesive composition for use as a structural adhesive. The adhesive composition includes a first population of microcapsules encapsulating a monomer and a first-part curing agent including an initiator. The composition further includes a second-part curing agent. The second-part curing agent includes an activator and a catalyst. Preferably, the activator of at least the second-part curing agent is encapsulated in the second population of microcapsules. Reactive contact between the monomer and the first-part curing agent and the second-part curing agent is achieved by rupturing the microcapsules, allowing the respective capsule contents to leach into the reactive contact. This composition is suitable for forming a dry-touch adhesive. However, the composition is not suitable for high-performance bonding of a wide variety of substrates.

[0016] U.S. Patent No. 9,305,892 relates to an adhesive composition for pre-applied underfill sealants, comprising (a) a radically polymerizable monomer having one or more functional groups selected from the group consisting of vinyl, maleimide, acryloyl, methacryloyl, and allyl groups; (b) a polymer having polar groups; (c) a filler; and (d) a thermal radical initiator. The adhesive composition can be in liquid or film form. If in film form, the adhesive composition can be laminated to a support tape, after which the adhesive composition is B-staged. B-staging refers to heating the adhesive composition to a temperature where the individual components in the composition do not actively initiate reaction (cure), but the adhesive composition becomes dry, i.e., non-tacky, by volatilizing the solvent. In other cases, B-staging of the adhesive to a non-tacky state is achieved by partial curing or setting.

[0017] In the manufacture of complex products containing multiple components, such as cell phones, televisions, and computers, particularly those comprising electronic circuits, chipboards, packaging substrates, and displays, the manufacture of the components often occurs at a location separate from the location where the final product is assembled. The use of dry-touch adhesives advantageously facilitates pre-application of the curable adhesive to the components, allowing them to be shipped to another location without concern for adhesive contamination. This cannot be easily achieved using tacky-curable adhesives. Thus, it would be highly desirable to provide a curable adhesive composition that remains stable in its uncured, dry-touch state and can be subsequently activated when needed. It would also be highly advantageous to provide an adhesive that facilitates bonding of multiple substrate types, such as, for example, metal-to-metal bonding, metal-to-plastic bonding, glass-to-glass bonding, glass-to-metal bonding, glass-to-plastic bonding, and / or plastic-to-plastic bonding. Furthermore, it would be particularly desirable to provide a composition suitable for high-performance bonding. These and other needs are provided by the compositions disclosed herein. Summary of the Invention [Means for solving the problem]

[0018] In one aspect, the present invention provides a method for producing a pharmaceutical composition comprising: a liquid (meth)acrylate monomer component; a solid thermoplastic polyurethane resin having a molecular weight in the range of 40,000 g / mol to 100,000 g / mol and a melting point in the range of 40°C to 80°C; a solid curing polyurethane (meth)acrylate resin having a molecular weight in the range of 5,000 g / mol to 35,000 g / mol and a melting point in the range of 50°C to 80°C; A redox curable composition is provided that includes a curing component that cures a liquid (meth)acrylate monomer component.

[0019] Advantageously, the compositions of the present invention can be applied to a substrate in a molten state and solidified, for example, to form a dry-touch film on the substrate. Advantageously, when applied to a substrate from the molten state, the curable composition becomes non-flowable and solidifies within about 5 minutes at room temperature. An assembly can be formed by mating a substrate coated with the composition of the present invention with another substrate, and curing can be initiated by applying heat, if necessary, to melt the adhesive and initiate redox curing. The composition can be cured under anaerobic conditions; i.e., the redox-curable composition can be an anaerobic-curable composition. Curing of an anaerobic composition can be achieved by exposing the composition to an anaerobic environment.

[0020] The solid thermoplastic polyurethane resin has a molecular weight in the range of 40,000 g / mol to 100,000 g / mol and a melting point in the range of 40°C to 80°C. If the molecular weight is less than about 40,000 g / mol, the cured composition tends to be brittle. If the molecular weight range is greater than about 100,000 g / mol, the composition tends to be sticky, and it is difficult to achieve a dry touch.

[0021] The solid curing polyurethane (meth)acrylate resins have molecular weights ranging from 5,000 g / mol to 35,000 g / mol and melting points ranging from 50° C. to 80° C. This temperature range is optimal for redox-curing components, especially those containing peroxides.

[0022] The liquid (meth)acrylate monomer is present in an amount of about 10% to about 60% by weight based on the total weight of the curable composition, for example, in an amount of about 15% to about 55% by weight based on the total weight of the curable composition, and preferably in an amount of about 25% to about 50% by weight based on the total weight of the curable composition.

[0023] The solid thermoplastic polyurethane resin is present in an amount of about 5% to about 40% by weight based on the total weight of the curable composition, e.g., about 7.5% to about 30% by weight based on the total weight of the curable composition, about 10% to about 20% by weight based on the total weight of the curable composition, and preferably about 10% to about 18% by weight based on the total weight of the curable composition. Compositions containing less than about 5% by weight of the solid thermoplastic polyurethane resin identified herein tend to be brittle and exhibit poor structural bonding and solid formation properties. Compositions containing more than about 40% by weight of the solid thermoplastic polyurethane resin tend to have less effective adhesive properties when cured. The redox-curable compositions of the present invention achieve optimal dry-touch properties in the uncured state when the solid thermoplastic polyurethane resin is present in the composition in an amount of about 10% to about 20% by weight.

[0024] The solid curable polyurethane (meth)acrylate resin is present in an amount of about 20% to about 70% by weight, based on the total weight of the curable composition, for example, about 30% to about 65% by weight, based on the total weight of the curable composition, and preferably about 40% to about 60% by weight, based on the total weight of the curable composition. Compositions containing less than about 20% by weight of the solid curable polyurethane (meth)acrylate resin tend to be more liquid and are more difficult to form into dry-touch redox-curable compositions. Compositions containing more than about 70% by weight of the solid curable polyurethane (meth)acrylate resin tend to have less effective adhesive properties. Optimal dry times and adhesive performance are achieved when the redox-curable composition contains the solid curable polyurethane (meth)acrylate resin in an amount of about 30% to about 65% by weight.

[0025] The curing component that cures the liquid (meth)acrylate monomer component is present in an amount of about 0.1 to about 10%, e.g., about 1 to about 5% by weight, e.g., about 5% by weight, based on the total weight of the composition, and / or the curing component includes a peroxide.

[0026] The liquid (meth)acrylate monomer component has the formula: H2C=CGCO2R 8 The number of the suffixes may be one or more selected from the group consisting of: During the ceremony, G may be hydrogen, halogen, or an alkyl group having 1 to 4 carbon atoms; R 8 is selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, alkaryl, or aryl groups having 1 to about 16 carbon atoms, and may be optionally substituted or interrupted with silane, silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, carbonate, amine, amide, sulfur, sulfonate, sulfone, etc.

[0027] The curing agent may comprise one or more selected from the group consisting of 1-acetyl-2-phenylhydrazine, N,N-dimethyl para-toluidine, N,N-diethyl para-toluidine, N,N-diethanol para-toluidine, N,N-dimethyl orthotoluidine, N,N-dimethyl meta-toluidine, indoline, 2-methylindoline, isoindoline, indole, 1,2,3,4-tetrahydroquinoline, 3-methyl-1,2,3,4-tetrahydro-quinoline, 2-methyl-1,2,3,4-tetrahydroquinoline, and 1,2,3,4-tetrahydroquinoline-4-carboxylic acid.

[0028] The compositions of the present invention may further comprise an initiator of free radical polymerization, such as a peroxide.

[0029] The initiator for the free radical polymerization may be one or more selected from the group consisting of cumene hydroperoxide ("CHP"), paramenthane hydroperoxide, t-butyl hydroperoxide ("TBH"), t-butyl perbenzoate, benzoyl peroxide, dibenzoyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, diacetyl peroxide, 4,4-bis(t-butylperoxy)butyl valerate, p-chlorobenzoyl peroxide, t-butylcumyl peroxide, butyl t-perbenzoate, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,5-dimethyl-2,5-di-t-butyl-peroxyhex-3-yne, 4-methyl-2,2-di-t-butylperoxypentane, t-amyl hydroperoxide, 1,2,3,4-tetramethylbutyl hydroperoxide, and combinations thereof.

[0030] The free radical cure-accelerating component may include an encapsulated peroxide.

[0031] The composition of the present invention can further comprise a cure accelerator. Advantageously, the presence of the cure accelerator accelerates the curing of the composition of the present invention on "inactive" or "passive" substrates, such as plastic substrates. Advantageously, the presence of the cure accelerator accelerates the curing of the composition of the present invention on "inactive" or "passive" substrates, such as plastic substrates. Furthermore, the presence of the cure accelerator accelerates the curing throughout the volume of the adhesive composition when a bond gap exists between the substrates to be bonded.

[0032] Suitably the cure accelerator may comprise one or more metallocenes such as ferrocene, suitably n-butylferrocene.A particularly useful cure accelerator is benzoylcyclohexylthiourea.

[0033] The compositions of the present invention can be applied by any method, with one advantage being that they can be prepared and / or applied to a substrate by methods that do not require the use of solvents. Therefore, no solvent (organic solvent or water) is required.This avoids the need for a liquid carrier for the composition.The composition of the present invention is essentially dry, and as a result has the advantage of being easy to handle.For example, the composition of the present invention is particulate and flowable, does not require a liquid carrier, and does not need to dry solvent or water to achieve application to a substrate.

[0034] Thus, for example, dry handling of the product on a production line is achievable and advantageous. Once applied (to a substrate), the compositions of the present invention also dry. Dry-to-the-touch products are desirable from a handling perspective to eliminate contamination, smearing, spills, loss of composition from the substrate, and the like. Advantageously, the compositions of the present invention can be used to form a pre-applied dry-to-the-touch adhesive on a substrate, for example, by heating the curable composition from its solid state to a molten state, then applying the molten curable composition to the substrate at room temperature, and allowing the molten curable composition to cool and solidify on the substrate, thereby forming a pre-applied adhesive on the substrate. The curable composition goes from a molten state to a dry-to-the-touch adhesive within a period of less than about 5 minutes, preferably within a period of about 30 to 300 seconds, e.g., within a period of about 30 to 120 seconds, after application to the substrate at room temperature.

[0035] The compositions of the present invention have many of the same end uses as conventional anaerobic curable compositions.

[0036] It will be appreciated that, since the compositions of the present invention are solid, they may be provided in any designed form / shape.

[0037] Another aspect of the present invention provides a cured composition formed by curing the curable composition of the present invention claimed herein. Suitably, the curable composition can be cured by exposure to an anaerobic environment. For example, the curable composition can be cured by exposure to an anaerobic environment for a time period ranging from about 1 minute to about 30 minutes, e.g., from about 1 minute to about 20 minutes. Optionally, the curable composition can be cured within a temperature range of about 40°C to about 100°C. For example, the curable composition can be cured by exposure to an anaerobic environment for a time period ranging from about 1 minute to about 30 minutes within a temperature range of about 40°C to about 100°C.

[0038] In another aspect, the present invention provides a method of bonding two substrates together, comprising: applying the redox-curable composition of the present invention to at least one substrate; and mating the substrates to form a mated assembly for a period of time sufficient for curing of the redox-curable composition to occur.

[0039] Preferably, curing of the redox-curable composition is initiated by heating the curable composition and / or exposing the curable composition to pressure. Curing of the redox-curable composition can be initiated by exposing the curable composition to an anaerobic environment. Optionally, curing of the redox-curable composition is initiated by heating the curable composition and / or exposing the curable composition to pressure in an anaerobic environment.

[0040] The substrates may be mated using a heat press, which applies a pressure of at least 2 bar to the mated assembly, suitably at least 4 bar.

[0041] In the method of the present invention, the composition of the present invention can be cured by applying heat and / or pressure to the mated assembly for 30 seconds or more, for example, 1 minute or more, for example, 5 minutes or more, or 20 minutes or more. For example, heat and / or pressure is applied to the mated assembly for 1 minute to 20 minutes.

[0042] Prior to applying the redox-curable composition of the present invention, one or more substrates to be bonded can be primed with a primer. Advantageously, applying a primer facilitates bonding of a wide variety of substrates using the composition of the present invention. Suitably, the primer can be a thiourea or thiourethane. [Brief explanation of the drawings]

[0043] [Figure 1] FIG. 1 shows a DSC thermogram of a solid thermoplastic polyurethane resin for use in the present invention, the resin having a molecular weight in the range of 40,000 g / mol to 100,000 g / mol. [Figure 2] FIG. 2 shows DSC thermograms of solid curable polyurethane (meth)acrylate resins for use in the present invention, the resins having molecular weights ranging from about 5,000 g / mol to 35,000 g / mol. DETAILED DESCRIPTION OF THE INVENTION

[0044] (Detailed explanation) As outlined above, the present invention provides a liquid (meth)acrylate monomer component, a solid thermoplastic polyurethane resin having a molecular weight in the range of 40,000 g / mol to 100,000 g / mol and a melting point in the range of 40°C to 80°C; a solid curing polyurethane (meth)acrylate resin having a molecular weight in the range of 5,000 g / mol to 35,000 g / mol and a melting point in the range of 50°C to 80°C; A redox-curable composition, such as an anaerobic curable composition, is provided that includes a curing component that cures a liquid (meth)acrylate monomer component.

[0045] <Definitions and standard test methods> The term "liquid" means in a liquid state within a temperature range of about 5°C to 30°C, preferably at room temperature and atmospheric pressure.

[0046] The term "solid" refers to a solid state within a temperature range of about 5°C to 40°C, preferably at room temperature and atmospheric pressure. The solid state is defined as a state of matter in which the material is not fluid, maintains boundaries without support, and the atoms or molecules occupy fixed positions relative to one another and are not free to move. The pre-applied adhesive compositions of the present invention are substantially dry to the touch. The compositions can be applied to a substrate from the molten state, whereupon they form a dry-touch, solid, curable composition. Dry to the touch is defined as non-flowable within a period of up to 5 minutes at room temperature, suitably within a period of about 30 seconds to about 300 seconds at room temperature, suitably within about 30 seconds to 120 seconds at room temperature.

[0047] Molecular weights disclosed herein are determined in accordance with ISO 13885-1:2008, "Binders for paints and varnishes - Gel permeation chromatography (GPC) - Part 1: Tetrahydrofuran (THF) as eluent."

[0048] The melting and resolidification temperature ranges were measured according to ISO 1137-1:2016 "Plastics - Differential scanning calorimetry (DSC) - Part 1 General principles."

[0049] The liquid (meth)acrylate ingredients are β-carboxyethyl acrylate, isobornyl acrylate, n-octyl acrylate, n-decyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl acrylate, ethoxyethoxyethyl acrylate, ethoxylated phenyl monoacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, isooctyl acrylate, n-butyl acrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, glycerol triacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate. The composition may comprise one or more (meth)acrylate monomers selected from acrylate, pentaerythritol tetraacrylate, phenoxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, cyclohexyl methacrylate, glycerol monomethacrylate, glycerol 1,3-dimethacrylate, trimethylcyclohexyl methacrylate, methyl triglycol methacrylate, isobornyl methacrylate, trimethylolpropane trimethacrylate, neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, hydroxybutyl methacrylate, tetrahydrofurfuryl methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, glycerol methacrylate, glycidyl methacrylate, methyl methacrylate, methacrylic acid, and mixtures thereof.

[0050] Preferred liquid (meth)acrylate monomers include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, phenoxyethyl methacrylate, and methacrylic acid.

[0051] The composition may also comprise a solid (meth)acrylate in the range of about 5% to about 15%, based on the total weight of the composition.

[0052] Additionally, the one or more suitable (meth)acrylates may be selected from, but are not limited to, di- or tri-functional (meth)acrylates such as polyethylene glycol di(meth)acrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate ("TRIEGMA"), tetraethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, di-(pentamethylene glycol) dimethacrylate, tetraethylene diglycol diacrylate, diglycerol tetramethacrylate, tetramethylene dimethacrylate, ethylene dimethacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, polyethylene glycol di(meth)acrylate, and polyfunctional (meth)acrylates of 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.

[0053] For example, the redox curable component is bisphenol A dimethacrylate. [ka] may include:

[0054] Suitably, the redox curable composition may comprise an ethoxylated bisphenol A di(meth)acrylate.

[0055] Still other (meth)acrylates suitable for use herein include silicone (meth)acrylate moieties (“SiMA”) as taught and claimed by U.S. Pat. No. 5,605,999 (Chu), the disclosure of which is expressly incorporated herein by reference.

[0056] Other suitable materials may be selected from polyacrylate esters represented by the following formula:

[0057] [ka] During the ceremony, R 4 is a group selected from hydrogen, halogen, or alkyl having 1 to about 4 carbon atoms; q is an integer equal to at least 1, preferably 1 to about 4; and X is an organic group containing at least 2 carbon atoms and having a total binding capacity of q+1. Regarding the upper limit of the number of carbon atoms in X, there are monomers that can function with essentially any value. However, in practice, a common upper limit is about 50 carbon atoms, preferably 30, and most preferably about 20.

[0058] For example, X can be an organic group of the formula:

[0059] [ka] During the ceremony, Y 1 and Y 2 Each of is an organic group such as a hydrocarbon group containing at least 2 carbon atoms, desirably from 2 to about 10 carbon atoms, and Z is an organic group, preferably a hydrocarbon group containing at least 1 carbon atom, preferably from 2 to about 10 carbon atoms.

[0060] Other monomers may be selected from the reaction products of di- or tri-alkylolamines (for example ethanolamine or propanolamine) with acrylic acid, as disclosed in French Patent No. 1,581,361.

[0061] Suitable oligomers having (meth)acrylate functionality may also be used. Examples of such (meth)acrylate-functionalized oligomers include those having the following general formula:

[0062] [ka] In the formula, R 5 is hydrogen, alkyl having 1 to about 4 carbon atoms, hydroxyalkyl having 1 to about 4 carbon atoms, or

[0063] [ka] is a group selected from R 4 is a group selected from hydrogen, halogen, or alkyl having 1 to about 4 carbon atoms; R 6 is hydrogen, hydroxyl or

[0064] [ka] and m is an integer at least equal to 1, for example, 1 to about 15 or more, desirably 1 to about 8; n is an integer at least equal to 1, for example, 1 to about 40 or more, desirably about 2 to about 10; and p is 0 or 1.

[0065] Typical examples of acrylic acid ester oligomers corresponding to the above general formula include di-, tri-, and tetraethylene glycol dimethacrylate; di(pentamethylene glycol) dimethacrylate; tetraethylene glycol diacrylate; tetraethylene glycol di(chloroacrylate); diglycerol diacrylate; diglycerol tetramethacrylate; butylene glycol dimethacrylate; neopentyl glycol diacrylate; and trimethylolpropane triacrylate.

[0066] Di- and other polyacrylate esters, particularly those described in the previous paragraph, are preferred, although monofunctional acrylate esters (esters containing one acrylate group) can also be used.

[0067] Suitable compounds may be selected from among cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, t-butylaminoethyl methacrylate, cyanoethyl acrylate, and chloroethyl methacrylate.

[0068] Another useful class of materials are the reaction products of (meth)acrylate-functionalized, hydroxyl- or amino-containing materials with polyisocyanates in appropriate proportions to convert all isocyanate groups to urethane or ureido groups, respectively.

[0069] The (meth)acrylate urethane or urea ester so formed may contain hydroxy or amino functional groups in the non-acrylate portion. Suitable (meth)acrylate esters for use are those of the formula

[0070] [ka] During the ceremony, X is -O- and

[0071] [ka] is selected from R 9 is selected from hydrogen or lower alkyl having 1 to 7 carbon atoms; R 7 is selected from hydrogen, halogen (e.g., chlorine), or alkyl (e.g., methyl and ethyl groups), and R 8 is a divalent organic group selected from alkylene, phenylene, and naphthylene having 1 to 8 carbon atoms.

[0072] These groups, upon appropriate reaction with a polyisocyanate, produce monomers of the general formula:

[0073] [ka] wherein n is an integer from 2 to about 6; B is a polyvalent organic group selected from substituted and unsubstituted alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, alkaryl, and heterocyclic groups and combinations thereof; R 7 , R 8 and X has the above meaning.

[0074] Depending on the properties of B, these (meth)acrylate esters having urea or urethane bonds may have a molecular weight that places them in the oligomeric class (such as from about 1,000 g / mol to about 5,000 g / mol) or polymeric class (e.g., greater than about 5,000 g / mol).

[0075] Styrenic, maleimide, vinyl ether, allyl, allyl ether, and other unsaturated reactive monomers and oligomers such as those described in US Pat. No. 6,844,080 B1 (Kneafsey et al.) can be used. Vinyl resins such as those described in US Pat. No. 6,433,091 (Xia) can also be used. Methacrylate or acrylate monomers containing these unsaturated reactive groups can also be used.

[0076] Of course, combinations of these (meth)acrylates with other monomers can also be used.

[0077] <Solid-curing polyurethane (meth)acrylate resin> The solid polyurethane(meth)acrylate resin component for use in the present invention can be prepared by reacting a polyol with a diisocyanate to form a polyurethane containing free isocyanate groups, and then reacting the polyurethane containing free isocyanate groups with a hydroxyl-functionalized (meth)acrylate component to form a curable polyurethane(meth)acrylate resin. As outlined above, the curable polyurethane(meth)acrylate resin used in the present invention is solid and has a molecular weight ranging from about 5,000 g / mol to about 35,000 g / mol and a melting point ranging from about 50°C to about 80°C.

[0078] Suitably, the polyol has a molecular weight in the range of 1,000 to 10,000 g / mol. For example, the polyol may be a polyester polyol such as the reaction product of a polybasic carboxylic acid selected from dibasic to tetrabasic carboxylic acids with a polyhydric alcohol selected from dihydric, trihydric, tetrahydric or pentahydric alcohols.

[0079] Suitably, the polyol has a molecular weight in the range of from 1,500 g / mol to about 4,500 g / mol, such as from about 2,000 g / mol to about 4,500 g / mol, for example from about 3,250 g / mol to about 3,750 g / mol.

[0080] The polyester polyols may have a hydroxyl number in the range of 25 to 55, for example about 27 to 54, such as 27 to 34, measured according to DIN EN ISO 4629-2.

[0081] Suitably, the polyester polyol has a melting point in the range of from 45°C to 75°C, for example from 55°C to 75°C, preferably from 60°C to 75°C, as measured by DSC.

[0082] The polyol may have a viscosity in the range of 0.3 to 2.3 Pa.s at 80°C, measured using the parallel plate method. The method used to determine viscosity at room temperature or above is based on BS5350 Part B8 "Test methods for adhesives, determination of viscosity".

[0083] The diisocyanate component is suitably an aromatic diisocyanate. For example, the diisocyanate may be selected from toluene diisocyanate, methylene phenyl diisocyanate, and an aliphatic diisocyanate selected from isophorone diisocyanate, hexamethylene diisocyanate, and methylene bis(4-cyclohexyl isocyanate).

[0084] The (meth)acrylate component reacted with the polyurethane can be selected from acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, methacrylic acid, monoethyl phthalate methacrylate, monoethyl maleate methacrylate and monoethyl succinate maleate.

[0085] <Synthesis of solid polyurethane (meth)acrylate resin> Examples of raw materials used in the synthesis of solid polyurethane (meth)acrylate resins (a) Polyol: (Semi)crystalline polyester polyols, such as those available from Evonik under the trade name Dynacoll, e.g. Dynacoll 7380, 7381, 7362 (b) Isocyanates: Toluene diisocyanate Methylene diphenyl isocyanate Hydrogenated xylylene diisocyanate (c) Capping agent: Hydroxyethyl methacrylate Glycerol dimethacrylate

[0086] <Synthesis example of solid polyurethane (meth)acrylate> Dynacoll 7380 (90.89 g), BHT (butylated hydroxytoluene) (0.03 g), MEHQ (4-methoxyphenol) (0.03 g), and phosphoric acid (0.007 g) were added to a reaction vessel and mixed while heating to 120 °C. The temperature was reduced, and mixing continued at 100 °C for 20 minutes. DBTDL (dibutyltin dilaurate) (0.037 g) was added with mixing, followed by TDI (toluene diisocyanate) (6.28 g) slowly added to the reaction mixture while maintaining the temperature at 100 °C throughout the reaction. Mixing continued for 2-3 hours, or until the percentage of isocyanate (NCO) reached equilibrium. A sample of the reaction mixture was titrated to quantify the remaining NCO. Ninety percent (~2.5 g) of the required weight percent of HEMA (hydroxyethyl methacrylate) based on titer was added to the reaction mixture, followed by 0.037 g of DBTDL. Mixing was continued for 3 hours, and the reaction was monitored for NCO consumption by titration. When the % NCO remaining was greater than 0.2% (molar) and equilibrated, the remaining 10% weight percent of HEMA was added. The reaction was stopped when the NCO content was <0.2% (molar).

[0087] The compositions of the present invention contain a solid thermoplastic polyurethane resin having a molecular weight in the range of 40,000 g / mol to 100,000 g / mol and a melting point in the range of 40° C. to 80° C. Suitable solid thermoplastic polyurethane resins include Pearlbond® 100, Pearlbond® 106, Pearlbond® 120, Pearlbond® 122, Pearlbond® 180, Pearlstick® 5712, Pearlstick® 5714, and Pearlstick® 40-70 / 08, which are commercially available from Lubrizol, Carrer del Gran Vial, 17, 08160 Montmelo, Barcelona, Spain.

[0088] <Primer> As outlined above, the composition of the present invention can be used in combination with a primer. For example, the substrate can be primed with a primer before applying the composition of the present invention to the substrate. A primer sold by Henkel under the trade name Loctite® 7952 is particularly useful. The primer composition suitably contains a thiourea or thiourethane, preferably one or more benzoylthioureas or benzoylthiourethanes. Suitable examples of benzoylthioureas and / or benzoylthiourethanes are disclosed in U.S. Pat. No. 9,371,473 B2, the contents of which are incorporated herein by reference in their entirety, particularly from column 3, line 56 to column 8, line 10.

[0089] Particularly preferred primers include one or more of benzoylcyclohexylthiourea, tetramethylthiourea, tetraethylthiourea, dimethyldiethylthiourea, benzoylthiourea, allylthiourea, acetylthiourea, thiourethane, benzoyloctylthiourea, and benzoylmorpholinothiourea. [Example]

[0090] <Example 1> [Table 1]

[0091] The compositions in Table 1 were prepared by premixing HEMA with pellets of solid TPU resin (Pearl Bond 100) under high shear. The remaining ingredients (except cumene hydroperoxide) were then added to the HEMA and TPU resin mixture while mixing. After the mixture was homogeneous, the cumene hydroperoxide was added and mixed. Mixing was performed in a sealed container using a Speedmixer™ Model DAX150.1FVZ.K. The container was cooled to room temperature, and the adhesive mixture therein was allowed to solidify.

[0092] GF-polyarylamide substrates were primed with Loctite® 7952 primer containing 5 wt. % benzoylcyclohexylthiourea based on the total weight of the primer before applying the compositions of Table 1. Stainless steel substrates were primed with Loctite® 7952 primer containing 0.5 wt. % 2-hydroxyethyl methacrylate phosphate based on the total weight of the primer.

[0093] Application of the adhesive to form the pre-applied adhesive was accomplished by heating the composition of Table 1 to 65°C to make it flowable, and then applying the flowable composition to the primed lap shear substrate at room temperature, after which the composition rapidly formed a solid.

[0094] 322.6mm 2 (0.5 inches 2 A sufficient amount of adhesive composition was applied to the overlapping shear substrate to ensure complete coverage of the adhesive area of the adhesive.

[0095] The pre-applied adhesive composition was applied to a glass-filled polyarylamide lap shear substrate by applying a 0.5 inch adhesive to a stainless steel lap shear substrate. 2 The adhesive area was evaluated for bonding. Curing was performed as outlined in Table 2. [Table 2]

[0096] Tensile strength was determined according to ISO 4587. Results are presented as the mean with standard deviation within the set of specimens shown. Unless otherwise stated, assemblies were tested without an induction gap (zero gap).

[0097] It is clear from Table 2 that there is little difference in the tensile strength obtained when curing for 1 minute or 20 minutes at 65° C. Thus, the compositions of the present invention can be cured as needed.

[0098] Table 3 provides a comparison of the tensile strength of the compositions of the present invention and a 2K methyl methacrylate structural binder. [Table 3]

[0099] Table 3 shows that the pre-applied adhesive of the present invention provides adhesion comparable to that of a commercially available 2K methyl methacrylate adhesive.

[0100] <Example 2> [Table 4]

[0101] The compositions in Table 4 were prepared in the same manner as the compositions in Example 1 above.

[0102] The pre-applied adhesive composition of Example 2 was evaluated over a half-inch bond area to bond one glass-filled polyarylamide substrate to another. Prior to applying the composition of Table 4, one of the glass-filled polyarylamide substrates was primed with Loctite® 7952 primer containing 5 wt. % benzoylcyclohexylthiourea. The second glass-filled polyarylamide substrate was primed with Loctite® 7952 only. The first and second substrates were mated using a heat press maintained at a bondline temperature of 65°C at 4 bar pressure for 20 minutes before resting at room temperature for 30 minutes.

[0103] The bond strength of the pre-applied adhesive composition of Example 2 was evaluated for bonding two glass-filled polyarylamide substrates using zero gap and 0.125 mm gap conditions. The bond strengths are shown in Table 5. Again, bond strength (tensile strength) was evaluated according to ISO 4587.

[0104] [Table 5]

[0105] Advantageously, the compositions of the present invention can be used to bond passive substrates such as plastics. Furthermore, improved adhesive performance has been observed with the presence of a gap spacer.

[0106] <Example 3> [Table 6]

[0107] The composition of Example 3 was prepared in the same manner as the compositions of Examples 1 and 2 by premixing HEMA with pellets of solid TPU resin (Pearl Bond 100) under high shear, followed by adding the remaining ingredients during mixing. Mixing was performed in a closed container using a Speedmixer™ Model DAX150.1FVZ.K. The container was cooled to room temperature, and the adhesive mixture therein was allowed to solidify.

[0108] The substrate was primed prior to application of the pre-applied adhesive. The pre-applied adhesive composition adhered the glass-filled polyarylamide substrate to the stainless steel substrate to a thickness of 0.5 in. 2 The glass-filled polyarylamide substrates were pre-primed with Loctite® 7952 and the stainless steel substrates were pre-primed with Loctite® 7952 containing 0.5 wt % HEMA phosphate.

[0109] Application of the adhesive compositions in Table 6 to form pre-applied adhesives was accomplished by heating the compositions to 65°C to make them flowable, then applying the flowable compositions to primed glass-filled polyarylamide substrates at room temperature, where they rapidly formed solids. The pre-applied adhesives on the primed glass-filled polyarylamide substrates and primed stainless steel substrates were mated using a heat press at a bondline temperature of 65°C and 4 bar pressure for 20 minutes, followed by 24 hours at room temperature and atmospheric pressure. The tensile strength of the adhesive bonds was then evaluated according to ISO 4587. The average bond strength of the cured composition of Example 3 on glass-filled polyarylamide substrates bonded to SUS304 stainless steel substrates is shown in Table 7.

[0110] [Table 7]

[0111] <Example 4> A thin film of the adhesive composition of Example 1 was prepared by dispensing the molten adhesive composition of Example 1 between two sheets of polyester release liner (Melinex) sandwiched between two heated glass plates. No spacers were used to keep the sheet as thin as possible. Once dispensing was complete, the glass plates were allowed to cool, and the film containing the solidified adhesive composition of Example 1 between the two sheets of Melinex was removed and cut into strips. The tensile strength of the adhesive film was evaluated for bonding a primed glass-filled polyarylamide substrate to a primed stainless steel substrate. The glass-filled polyarylamide substrate was primed with Loctite® 7952 containing 5 wt. % benzoylcyclohexylthiourea, and the stainless steel substrate was primed with Loctite® 7952 containing 0.5 wt. % HEMA phosphate. The release liner was peeled from one side of the adhesive film, and the adhesive film was applied (by hand pressure) to the primed glass-filled polyarylamide substrate. The second release liner was then removed from the opposite side of the adhesive film, and the pre-applied adhesive to the glass-filled polyarylamide substrate was mated to a primed stainless steel substrate using a heat press at a bondline temperature of 65°C and 4 bar pressure for 1 minute, followed by 24 hours at room temperature and atmospheric pressure. The tensile strength of the adhesive bond was then evaluated according to ISO 4587. The average bond strength of the cured composition of Example 1, for glass-filled polyarylamide substrate bonded to SUS304 stainless steel substrate, is shown in Table 8.

[0112] [Table 8]

[0113] When used in reference to the present invention, the words "comprises" and "having" are used to specify the presence of stated features, integers, steps or components, but do not exclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0114] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

Claims

1. a liquid (meth)acrylate monomer component; a solid thermoplastic polyurethane resin having a molecular weight in the range of 40,000 g / mol to 100,000 g / mol and a melting point in the range of 40° C. to 80° C.; a solid curable polyurethane (meth)acrylate resin having a molecular weight in the range of 5,000 g / mol to 35,000 g / mol and a melting point in the range of 50°C to 80°C; 1. A redox curable composition comprising a curing component that cures a liquid (meth)acrylate monomer component, a liquid (meth)acrylate monomer in an amount of 10% to 60% by weight, based on the total weight of the curable composition; a solid thermoplastic polyurethane resin in an amount of 5% to 40% by weight; A composition wherein the solid curable methacrylate resin is present in an amount of from 20% to 70% by weight.

2. The composition of claim 1, wherein the liquid (meth)acrylate monomer is present in an amount of 25% to 50% by weight, based on the total weight of the curable composition.

3. The composition of claim 1 or 2, wherein the solid thermoplastic polyurethane resin is present in an amount of 10% to 30% by weight, based on the total weight of the curable composition.

4. The composition of any one of claims 1 to 3, wherein the solid curable methacrylate resin is present in an amount of 40% to 60% by weight, based on the total weight of the curable composition.

5. 5. The composition of claim 1, wherein the curing component that cures the liquid (meth)acrylate monomer component is present in an amount of 0.1 to 10 wt %, based on the total weight of the composition, and / or the curing component comprises a peroxide.

6. The liquid (meth)acrylate monomer component has the formula: H ２ C=CGCO ２ R ８ 、 (In the formula, G is hydrogen, halogen, or an alkyl group having 1 to 4 carbon atoms; R ８ is selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl or aryl groups having 1 to 16 carbon atoms, optionally substituted or interrupted with one or more selected from silane, silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, carbonate, amine, amide, sulfur, sulfonate, sulfone. The composition according to any one of claims 1 to 5, wherein the compound is one or more selected from the group consisting of:

7. The composition according to any one of claims 1 to 6, wherein the curing agent comprises one or more selected from the group consisting of 1-acetyl-2-phenylhydrazine, N,N-dimethyl para-toluidine, N,N-diethyl para-toluidine, N,N-diethanol para-toluidine, N,N-dimethyl orthotoluidine, N,N-dimethyl meta-toluidine, indoline, 2-methylindoline, isoindoline, indole, 1,2,3,4-tetrahydroquinoline, 3-methyl-1,2,3,4-tetrahydroquinoline, 2-methyl-1,2,3,4-tetrahydroquinoline, and 1,2,3,4-tetrahydroquinoline-4-carboxylic acid.

8. The composition of claim 1, further comprising an initiator for free radical polymerization.

9. 9. The composition of claim 8, wherein the free radical polymerization initiator is one or more selected from the group consisting of cumene hydroperoxide ("CHP"), paramenthane hydroperoxide, t-butyl hydroperoxide ("TBH"), t-butyl perbenzoate, benzoyl peroxide, dibenzoyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, diacetyl peroxide, 4,4-bis(t-butylperoxy)butyl valerate, p-chlorobenzoyl peroxide, t-butylcumyl peroxide, t-butylperbenzoate, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,5-dimethyl-2,5-di-t-butyl-peroxyhex-3-yne, 4-methyl-2,2-di-t-butylperoxypentane, t-amyl hydroperoxide, 1,2,3,4-tetramethylbutyl hydroperoxide, and combinations thereof.

10. 10. The composition of claim 8 or 9, wherein the free radical cure-accelerating component comprises an encapsulated peroxide.

11. The composition of any one of claims 1 to 10, further comprising a cure accelerator.

12. The composition of claim 11 , wherein the cure accelerator comprises one or more metallocenes.

13. The composition according to any one of claims 1 to 12, wherein the redox-curable composition is an anaerobic-curable composition.

14. A cured composition formed by curing the curable composition according to any one of claims 1 to 13.

15. 15. The cured composition of claim 14 formed by curing the curable composition by exposing the curable composition to an anaerobic environment.

16. 16. The curable composition of claim 15, wherein the curable composition is exposed to an anaerobic environment for a time ranging from 1 minute to 30 minutes, and optionally curing occurs at a temperature ranging from 40°C to 100°C.

17. 14. A method of bonding two substrates together comprising applying the redox-curable composition of any one of claims 1 to 13 to at least one of the substrates and mating the substrates for a time sufficient for curing of the redox-curable composition to occur to form a mated assembly.

18. 18. The method of claim 17, wherein curing of the redox-curable composition is initiated by heating the curable composition and / or exposing the curable composition to pressure.

19. 19. The method of claim 17 or 18, wherein the substrates are mated using a heat press.

20. 20. The method of claim 19, wherein the heat press applies a pressure of at least 2 bar to the mating assembly.

21. The method of any one of claims 17 to 20, wherein heat and / or pressure is applied to the mating assembly for a period of 30 seconds or more.

22. The method of claim 21, wherein the heat and / or pressure is applied to the mating assembly for between 1 minute and 20 minutes.

23. The method of any one of claims 17 to 22, wherein one or both substrates are primed with a primer prior to application of the redox curable composition.

24. The method of claim 23 wherein the primer comprises a thiourea and / or a thiourethane.

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