Curable precursor of adhesive composition

Abstract

The present disclosure relates to a curable precursor of an adhesive composition, the curable precursor comprising: (a) a radically (co)polymerizable (meth)acrylate-based component, (I C 1 ~C 32 (meth)acrylic acid ester monomer; (ii) a radical (co)polymerizable (meth)acrylate-based component comprising an ethylenically unsaturated acidic compound; (b) a crosslinker for the (meth)acrylate based component, comprising at least one acid functional group derived from phosphoric acid and at least one radically (co)polymerizable reactive group; (c) a nitroxide, C 1 ~C 32 The present invention relates to a curable precursor, wherein the (meth)acrylic acid ester monomer (a)(i) does not contain any functional group other than a (meth)acrylic acid ester group, and the ethylenically unsaturated acidic compound (a)(ii) does not contain any acid functional group derived from phosphoric acid. The present disclosure further relates to methods for producing cured compositions from the curable precursors and to the use of the curable precursors for adhesive and / or thermal management applications in the automotive industry.

Description

[Technical field]

[0001] The present disclosure relates to curable precursors of adhesive compositions that include a radically (co)polymerizable (meth)acrylate-based component. [Background technology]

[0002] Curable compositions have been known for many years as suitable for use in a variety of applications, including general-purpose industrial applications such as adhesives and coatings, as well as high-performance applications in the electronics industry, such as sealing and bonding electronic components. With the widespread use of curable compositions over the years, performance requirements have become increasingly stringent, particularly with regard to cure profile, adhesive performance, storage stability, handling and processability properties, as well as compliance with environmental and health requirements. When the curable composition is further required to provide thermal conductivity, formulating a suitable composition becomes even more difficult.

[0003] During storage of acrylic curable compositions, self-polymerization can occur, so inhibitors are usually used to prevent it. Most inhibitors require oxygen to ensure their functionality. Highly filled adhesive acrylic compositions with high viscosity, such as acrylic temperature control compositions, and also other adhesive acrylic curable compositions, show limited oxygen diffusion. As a result, core polymerization can occur, especially during storage of large quantities of highly filled acrylic compositions, for example when the curable composition is stored in a drum with a volume of 100 or 200 liters. During storage of the curable composition in a drum, oxygen is consumed by the inhibitor, but due to limited diffusion of oxygen to the core area of ​​the drum, sufficient oxygen is not available in the core area over time to ensure proper functionality of the inhibitor, resulting in core polymerization.

[0004] In adhesive acrylic compositions, acids can increase adhesive strength. The presence of acids such as acrylic acid in acrylic curable compositions makes it much more difficult to stabilize the curable composition for storage, since acids are highly reactive and tend to destabilize the composition, resulting in a higher tendency for core polymerization.

[0005] WO 2019 / 040596(A1) discloses a combination of inhibitors for increasing the shelf life of urethane (meth)acrylate compositions. The resin composition of WO 2019 / 040596(A1) comprises a urethane (meth)acrylate and an inhibitor package comprising at least one nitroxide radical and at least one base, the base being selected from the group consisting of a tertiary amine base, a quaternary ammonium hydroxide, an alkoxide, or a hydroxide. If a base is not added to the nitroxide or if an acid is added to the composition, a significantly reduced shelf life occurs.

[0006] There remains a need for curable precursors of adhesive acrylic compositions that have good storage stability and are curable at room temperature, especially when the curable precursor comprises an acrylic acid monomer.

[0007] As used herein, "a," "an," "the," "at least one," and "one or more" are used interchangeably. The term "comprising" is also intended to include the terms "consisting essentially of" and "consisting of." Summary of the Invention

[0008] In a first aspect, the present disclosure provides a curable precursor of an adhesive composition, the curable precursor comprising: (a) a radically (co)polymerizable (meth)acrylate-based component, (i) C1~C 32 (meth)acrylic acid ester monomer; (ii) an ethylenically unsaturated acidic compound; and A radical (co)polymerizable (meth)acrylate-based component comprising: (b) a crosslinker for the (meth)acrylate based component, comprising at least one acid functional group derived from phosphoric acid and at least one radically (co)polymerizable reactive group; (c) a nitroxide; Including, C1~C 32The present invention relates to a curable precursor, wherein the (meth)acrylic acid ester monomer (a)(i) does not contain any functional group other than a (meth)acrylic acid ester group, and the ethylenically unsaturated acidic compound (a)(ii) does not contain any acid functional group derived from phosphoric acid.

[0009] In another aspect, the present disclosure also provides a method for producing a cured composition from a curable precursor disclosed herein, the method comprising: providing a curable precursor, the curable precursor comprising: (a) a radically (co)polymerizable (meth)acrylate-based component, (i) C1~C 32 (meth)acrylic acid ester monomer; (ii) an ethylenically unsaturated acidic compound; and A radical (co)polymerizable (meth)acrylate-based component comprising: (b) a crosslinker for the (meth)acrylate based component, comprising at least one acid functional group derived from phosphoric acid and at least one radically (co)polymerizable reactive group; (c) a nitroxide; Including, C1~C 32 providing a curable precursor, in which the (meth)acrylic acid ester monomer (a)(i) does not contain any functional group other than a (meth)acrylic acid ester group, and the ethylenically unsaturated acidic compound (a)(ii) does not contain any acid functional group derived from phosphoric acid; Providing an initiator for the radical polymerization of a curable precursor; mixing a curable precursor and an initiator; curing the mixture of the curable precursor and the initiator; The present invention relates to a method comprising the steps of:

[0010] In yet a further aspect, the present disclosure relates to the use of the curable precursors disclosed herein for adhesive and / or thermal management applications in the automotive industry.

[0011] The curable precursors disclosed herein have good storage stability and low tendency of core polymerization during storage. The curable precursors disclosed herein can be stored in 100 or 200 liter drums for several months. In some embodiments of the present disclosure, the curable precursors are highly filled thermally conductive curable precursors, and even these highly filled curable precursors have low oxygen diffusion, the curable precursors have good storage stability and low tendency of core polymerization during storage.

[0012] Although the curable precursors disclosed herein are stabilized for storage, rapid curing at room temperature is still possible due to the small amount of nitroxide inhibitor required to prevent core polymerization. The performance of the cured product, i.e. properties such as hardness, overlap shear strength, elongation at break, and thermal conductivity, are not adversely affected.

[0013] Surprisingly, it has been found that small amounts of nitroxides can effectively prevent core polymerization in acrylic compositions containing acids such as acrylic acid or other polymerizable monomers with acid functionality. One skilled in the art would have expected that nitroxides could not be used when acids, particularly acrylic acid, are included in the curable composition. One skilled in the art would also have expected that nitroxides could only be used as inhibitors in a basic environment and that the absence of acidic components would be required. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A curable precursor of an adhesive composition, the curable precursor comprising: (a) a radically (co)polymerizable (meth)acrylate-based component, (i) C1~C 32 (meth)acrylic acid ester monomer; (ii) an ethylenically unsaturated acidic compound; and A radical (co)polymerizable (meth)acrylate-based component comprising: (b) a crosslinker for the (meth)acrylate based component, comprising at least one acid functional group derived from phosphoric acid and at least one radically (co)polymerizable reactive group; (c) a nitroxide; Including, C1~C 32 Disclosed herein is a curable precursor, wherein the (meth)acrylic acid ester monomer (a)(i) does not contain any functional groups other than (meth)acrylic acid ester groups, and the ethylenically unsaturated acidic compound (a)(ii) does not contain any acid functionality derived from phosphoric acid.

[0015] "Curable precursor" is intended to refer to a composition that can be cured using an initiator. The term "initiator" is intended to refer to a substance or group of substances that can start or initiate or contribute to the curing process of the curable precursor.

[0016] "Radically (co)polymerizable component" is intended to indicate a composition that can be cured using an initiator that contains or can generate free radicals. The radically (co)polymerizable component may contain only one, two, or more than two radically (co)polymerizable groups. Typical examples of radically (co)polymerizable groups include unsaturated carbon groups, such as vinyl groups present in (meth)acrylate groups.

[0017] As used herein, "(meth)acrylic" is a contraction of "acrylic" and / or "methacrylic". For example, "(meth)acrylate-based component" refers to "acrylate-based component" and / or "methacrylate-based component", and "C1-C 32 (Meth)acrylic acid ester monomers are C1-C 32 Acrylic acid ester monomers" and / or "C1-C 32 This refers to "methacrylic acid ester monomer."

[0018] As used herein, "(co)polymeric" is a contraction that refers to "polymeric" and / or "copolymeric."

[0019] A "monomer" is any chemical that can be characterized by a chemical formula having a radically (co)polymerizable unsaturated group (including a (meth)acrylate group) that can be polymerized into an oligomer or polymer to increase molecular weight. Usually, the molecular weight of a monomer can be simply calculated based on the given chemical formula.

[0020] The curable precursor of the adhesive composition disclosed herein comprises (a) a radically (co)polymerizable (meth)acrylate-based component, i.e., a radically (co)polymerizable acrylate-based component or a radically (co)polymerizable methacrylate-based component, or a combination thereof.

[0021] The radical (co)polymerizable (meth)acrylate-based component is (i) C1 to C 32 (Meth)acrylic acid ester monomers, i.e., C1-C 32 Acrylic acid ester monomer or C1-C 32 methacrylic acid ester monomers, or combinations thereof. 32 The (meth)acrylic acid ester monomer is a linear or branched C1-C 32 The radical (co)polymerizable (meth)acrylate component may be a C1-C (meth)acrylic acid ester monomer. 32 Contains acrylate monomers.

[0022] C1-C for use in radically (co)polymerizable (meth)acrylate-based components 32 The (meth)acrylic acid ester monomer may be selected from the group consisting of isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, methyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and any mixture thereof.

[0023] C1~C 32The (meth)acrylic acid ester monomer does not contain any functional groups other than the (meth)acrylic acid ester group.

[0024] The curable precursor is 1 to 50 wt%, 1 to 30 wt%, 1 to 20 wt%, 2 to 15 wt%, or 3 to 10 wt% of C1 to C 32 (Meth)acrylic acid ester monomers may be included, the weight percentages being based on the total weight of the curable precursor.

[0025] The radically (co)polymerizable (meth)acrylate-based component further comprises (ii) an ethylenically unsaturated acidic compound.

[0026] "Ethylenically unsaturated acidic compound" is intended to include monomers, oligomers, and polymers having ethylenic unsaturation and acid and / or acid precursor functionality.

[0027] Acidic precursor functionalities include, for example, anhydrides such as -CO-O-CO-, and acid halides.

[0028] The acidic groups preferably include one or more carboxylic acid residues, such as -COOH, or sulfonic acid residues, such as -SO3H.

[0029] "Polymer" or "polymeric material" are used interchangeably to refer to homopolymers, copolymers, terpolymers, and the like.

[0030] Specific examples of ethylenically unsaturated acidic compounds include, but are not limited to, di- or tri(meth)acrylated citric acid, poly(meth)acrylated oligomaleic acid, poly(meth)acrylated polymaleic acid, poly(meth)acrylated poly(meth)acrylic acid, poly(meth)acrylated polysulfonate, poly(meth)acrylated polyboric acid, and the like.

[0031] (Meth)acrylic acid and an alkanediol (e.g., C2-C 20 , or C2~C 12 , or C6~C 10) and reaction products with phosphorus oxide have also been found to be suitable.

[0032] Also usable are monomers, oligomers, and polymers of unsaturated carboxylic acids, such as (meth)acrylic acid, aromatic (meth)acrylated acids (e.g., methacrylated trimellitic acid), and their anhydrides. In some embodiments, acrylic acid or methacrylic acid is used as the ethylenically unsaturated acidic compound (ii).

[0033] The ethylenically unsaturated acidic compound (a)(ii) does not contain an acid functionality derived from phosphoric acid.

[0034] By "an acid functionality derived from phosphoric acid" it is meant that the acid functionality comprises a P-OH group; i.e., by "the ethylenically unsaturated acidic compound (a)(ii) does not comprise an acid functionality derived from phosphoric acid" it is meant that the ethylenically unsaturated acidic compound (a)(ii) does not comprise a P-OH group.

[0035] The curable precursor may comprise 0.1-20 wt%, 0.1-10 wt%, 0.1-5 wt%, 0.1-3 wt%, 0.1-2 wt%, 0.2-2 wt%, or 0.2-1 wt% of the ethylenically unsaturated acidic compound, the weight percentages being based on the total weight of the curable precursor.

[0036] The curable precursor may comprise 1-50 wt%, 1-30 wt%, 1-20 wt%, or 10-15 wt% of the (meth)acrylate component, where the weight percentages are based on the total weight of the curable precursor.

[0037] The curable precursor of the adhesive composition further comprises (b) a crosslinker for the (meth)acrylate-based component, the crosslinker comprising at least one acid functional group derived from phosphoric acid and at least one radically (co)polymerizable reactive group.

[0038] The crosslinker for the (meth)acrylate based component includes at least one acid functional group derived from phosphoric acid. The crosslinker for the (meth)acrylate based component may include at least two acid functional groups derived from phosphoric acid.

[0039] The at least one acid functional group derived from phosphoric acid of the crosslinker may include at least one P-OH group.

[0040] The at least one acid functional group derived from phosphoric acid of the crosslinker may be selected from the group consisting of monoesters of phosphoric acid, diesters of phosphoric acid, triesters of phosphoric acid, esters of diphosphoric acid, diesters of diphosphoric acid, and any combination or mixture thereof.

[0041] The at least one acid functional group derived from phosphoric acid of the crosslinker may be selected from the group consisting of a monoester of phosphoric acid and a C1-C6 polyol derivative, a diester of phosphoric acid and a C1-C6 polyol derivative, a triester of phosphoric acid and a C1-C6 polyol derivative, an ester of diphosphoric acid and a C1-C6 polyol derivative, a diester of diphosphoric acid and a C1-C6 polyol derivative, and any combination or mixture thereof.

[0042] According to a preferred embodiment of the present invention, the at least one acid functional group derived from phosphoric acid of the crosslinker is selected from the group consisting of monoesters of phosphoric acid and derivatives of the 1,3-isomer of glycerol, diesters of phosphoric acid and derivatives of the 1,3-isomer of glycerol, diesters of diphosphoric acid and derivatives of the 1,3-isomer of glycerol, and any combination or mixture thereof.

[0043] According to another preferred embodiment of the present invention, the at least one acid functional group derived from phosphoric acid of the crosslinker is selected from the group consisting of monoesters of phosphoric acid and derivatives of 1,2-isomers of glycerol, diesters of phosphoric acid and derivatives of 1,2-isomers of glycerol, diesters of diphosphoric acid and derivatives of 1,2-isomers of glycerol, and any combination or mixture thereof.

[0044] Crosslinkers for the (meth)acrylate based components contain at least one radically (co)polymerizable reactive group.

[0045] The crosslinker for the (meth)acrylate based component may contain at least two radically (co)polymerizable reactive groups.

[0046] In a preferred embodiment of the present disclosure, the crosslinker comprises at least one radically (co)polymerizable reactive group selected from the group consisting of ethylenically unsaturated groups.

[0047] In a more preferred embodiment of the present disclosure, the ethylenically unsaturated groups contained in the crosslinker are selected from the group consisting of (meth)acrylic groups, vinyl groups, styryl groups, and any combination or mixture thereof. More preferably, the ethylenically unsaturated groups are selected from the group consisting of methacrylic groups, acrylic groups, and any combination or mixture thereof.

[0048] In a particularly preferred embodiment of the present disclosure, the ethylenically unsaturated groups contained in the crosslinker are selected from the group of methacryl groups.

[0049] Advantageously, the crosslinking agents for use herein are ethylenically unsaturated compounds.

[0050] According to a particularly preferred embodiment, the crosslinker for use in the present disclosure comprises the reaction product of phosphoric acid and either 1,3-glycerol dimethacrylate or 1,2-glycerol dimethacrylate.

[0051] According to another particularly preferred aspect, the crosslinker for use in the present disclosure is selected from the group consisting of 1,3-glycerol dimethacrylate phosphate monoester, 1,2-glycerol dimethacrylate phosphate monoester, 1,3-glycerol dimethacrylate phosphate diester, 1,2-glycerol dimethacrylate phosphate diester, 1,3-glycerol dimethacrylate diphosphate diester, 1,2-glycerol dimethacrylate diphosphate diester, and any mixture thereof.

[0052] In an advantageous embodiment of the present disclosure, the crosslinker for the (meth)acrylate based component is (co)polymerizable with monomers (i) and / or (ii) of the (meth)acrylate based component.

[0053] In some embodiments, the crosslinking agent (b) may further have the function of an adhesion promoter.

[0054] The curable precursor of the present disclosure may comprise 0.01-10 wt%, 0.01-8 wt%, 0.05-6 wt%, 0.05-5 wt%, 0.05-4 wt%, 0.1-2 wt%, or even 0.1-1 wt% of a crosslinker for the (meth)acrylate based component, where the weight percentages are based on the total weight of the curable precursor.

[0055] The curable precursors disclosed herein further include nitroxides. Nitroxides are free radicals that contain the R2N-O· functional group. They are sometimes also called nitroxyl or aminoxyl radicals.

[0056] Nitroxides have the function of inhibitors of the curable precursors disclosed herein. Surprisingly, nitroxides have the function of inhibitors and can effectively prevent core polymerization despite the presence of acidic compounds in the curable precursors. The acidic compounds are included as ethylenically unsaturated acidic compounds in the radical (co)polymerizable (meth)acrylate-based components of the curable precursors, and the acidic compounds are included as at least one acid functional group derived from phosphoric acid in the crosslinker for the (meth)acrylate-based components. Those skilled in the art would have expected that nitroxides cannot act as inhibitors in acidic environments, and that the addition of bases and basic environments may be required for nitroxides to act as inhibitors.

[0057] The nitroxide may be selected from the group consisting of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), its derivatives, and combinations thereof.

[0058] Nitroxides include 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-hydroxy-TEMPO, TEMPOL), 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl (4-oxo-TEMPO), 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl acetate, 1-oxyl-2,2, 6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butylbenzoate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)succinate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipate, Bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)sebacate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)n-butylmalonate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)phthalate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)isophthalate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)terephthalate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)hexahydroterephthalate, N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipamine, It may be selected from the group consisting of N-1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-dodecylsuccinimide, 1-oxyl-4-methoxy-2,2,6,6-tetramethylpiperidine, 1-oxyl-4-amino-2,2,6,6-tetramethylpiperidine, and 1-oxyl-4-acetamino-2,2,6,6-tetramethylpiperidine.

[0059] Preferably, the nitroxide is 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-hydroxy-TEMPO, TEMPOL).

[0060] The curable precursor may comprise at least 0.001 wt.%, or at least 0.002 wt.%, or at least 0.003 wt.% of the nitroxide, based on the total weight of the curable precursor.

[0061] The curable precursor may comprise up to 0.1 wt.%, or up to 0.05 wt.%, or up to 0.02 wt.%, or up to 0.01 wt.%, or up to 0.008 wt.%, or up to 0.006 wt.%, or up to 0.005 wt.% of nitroxide, based on the total weight of the curable precursor.

[0062] The curable precursor may be present in an amount of 0.001 to 0.1% by weight, or 0.001 to 0.05% by weight, or 0.001 to 0.02% by weight, or 0.001 to 0.01% by weight, or 0.001 to 0.008% by weight, or 0.002 to 0.1% by weight, or 0.002 to 0.05% by weight, or 0.002 to 0.02% by weight, or 0.002 to 0.01% by weight, or 0.002 to 0.01% by weight, based on the total weight of the curable precursor. It may contain 0.008% by weight, or 0.002 to 0.004% by weight, or 0.003 to 0.1% by weight, or 0.003 to 0.05% by weight, or 0.003 to 0.02% by weight, or 0.003 to 0.01% by weight, or 0.003 to 0.008% by weight, or 0.003 to 0.006% by weight, or 0.003 to 0.005% by weight, or less than 0.003 to 0.005% by weight.

[0063] The curable precursors disclosed herein may further comprise (d) a polyether oligomer having a number average molecular weight of at least 2000 g / mol and containing at least one radically (co)polymerizable reactive group.

[0064] Unless otherwise indicated, the number average molecular weights of polyether oligomers for use herein are determined by conventional gel permeation chromatography (GPC) using suitable techniques well known to those skilled in the art.

[0065] Without wishing to be bound by theory, it is believed that the polyether oligomers described above act as reactive diluents and rheology modifiers for the curable precursors, contributing to providing the curable precursors with outstanding flexibility properties. The polyether oligomers are also believed to have a beneficial effect on the adhesive properties of the curable precursors, in particular due to the beneficial surface wetting properties provided by the oligomeric polyether moiety. In the case of curable precursors containing thermally conductive particles, the polyether oligomers described above are also believed to provide advantageous surface interactions with the thermally conductive particles, which contribute to allowing relatively high loadings of the thermally conductive particles, in particular due to the improved compatibility provided between the thermally conductive particles and the surrounding (meth)acrylate-based polymer matrix. Furthermore, the polyether oligomers for use herein are also believed to have a beneficial effect on shear strength and provide aging and hydrolytic stability, in particular due to the photocrosslinking effect provided by the radical (co)polymerizable reactive groups.

[0066] The polyether oligomer having a number average molecular weight of at least 2000 g / mol and comprising at least one radically (co)polymerizable reactive group may comprise a (linear) polyether backbone. The polyether oligomer comprises a polyether oligomer backbone that can be obtained by copolymerization of tetrahydrofuran units, ethylene oxide units and, optionally, propylene oxide units. The molar ratio of these monomers can range from 1:2.5 to 1:5, or even from 1:3 to 1:4.

[0067] Polyether oligomers for use herein may have a number average molecular weight of greater than 2000 g / mol, greater than 2500 g / mol, greater than 3000 g / mol, greater than 3500 g / mol, or even greater than 4000 g / mol.

[0068] Polyether oligomers for use herein may have a number average molecular weight of up to 20,000 g / mol, up to 15,000 g / mol, up to 12,000 g / mol, up to 10,000 g / mol, up to 9500 g / mol, up to 9000 g / mol, up to 8500 g / mol, or even up to 8000 g / mol.

[0069] Polyether oligomers for use herein may have a number average molecular weight in the range of 2000 to 20,000 g / mol, 2000 to 15,000 g / mol, 2000 to 12,000 g / mol, 2500 to 10,000 g / mol, 2500 to 9,000 g / mol, 3000 to 8500 g / mol, 3500 to 8000 g / mol, or even 4000 to 8000 g / mol.

[0070] In one advantageous embodiment, the polyether oligomers for use in the present disclosure contain at least two radically (co)polymerizable reactive groups.

[0071] According to another advantageous embodiment, at least one radically (co)polymerizable reactive group of the polyether oligomer is selected from the group consisting of ethylenically unsaturated groups. In other words, the polyether oligomer for use herein may be an ethylenically unsaturated compound.

[0072] In a more advantageous embodiment of the present disclosure, the ethylenically unsaturated groups contained in the polyether oligomer are selected from the group consisting of (meth)acrylic groups, vinyl groups, styryl groups, and any combination or mixture thereof. More preferably, the ethylenically unsaturated groups are selected from the group consisting of methacrylic groups, acrylic groups, and any combination or mixture thereof.

[0073] In a particularly preferred embodiment of the present disclosure, the ethylenically unsaturated group contained in the polyether oligomer is a methacryl group.

[0074] According to one advantageous aspect of the curable precursor of the present disclosure, the polyether oligomer for use herein has the following formula: [ka] [In the formula, Y is a radically (co)polymerizable reactive group, in particular an ethylenically unsaturated group, Each R2 is independently selected from the group consisting of alkylene groups having 2 to 6 carbons; n is an integer selected such that the number average molecular weight of the polyether oligomer is at least 2000 g / mol. has.

[0075] In one particular embodiment, n is selected to provide a number average molecular weight of at least 2000 g / mol, at least 3000 g / mol, or even at least 4000 g / mol. In another particular embodiment, n is selected to provide a number average molecular weight of at most 20,000 g / mol, at most 15,000 g / mol, or even at most 10,000 g / mol. In yet another particular embodiment, n is selected to provide a number average molecular weight of 2000-20,000 g / mol, 3000-15,000 g / mol, or even 3000-10,000 g / mol, all ranges including endpoints.

[0076] The curable precursor of the present disclosure may comprise 1-50 wt%, 1-30 wt%, 1-20 wt%, 2-15 wt%, or 3-10 wt% of the polyether oligomer, where the weight percentages are based on the total weight of the curable precursor.

[0077] The polyether oligomer is a (meth)acrylate-based component (a) having C1 to C 32 It is (co)polymerizable with the (meth)acrylic acid ester monomer (i) and the ethylenically unsaturated acidic compound (ii).

[0078] The radically (co)polymerizable (meth)acrylate-based component (a) of the curable precursor disclosed herein is (iii) Ethylenically unsaturated monomers having functional groups, the radical (co)polymerizable (meth)acrylate-based component (a) having C1-C 32An ethylenically unsaturated monomer that is copolymerizable with the (meth)acrylic acid ester monomer (i) and the ethylenically unsaturated acidic compound (ii). It may further include.

[0079] Without wishing to be bound by theory, it is believed that the presence of functionalized ethylenically unsaturated monomers in the (meth)acrylate-based component has a beneficial effect on its shear strength and adhesive properties. It is further believed that functionalized ethylenically unsaturated monomers provide favorable surface interactions with thermally conductive particles, which contribute to providing a favorable rheological profile to the curable precursor of the present disclosure.

[0080] Ethylenically unsaturated monomers having functional groups for use herein may have functional groups selected from the group consisting of amine, hydroxyl, amide, isocyanate, epoxide, nitrile, and any combination thereof.

[0081] The ethylenically unsaturated monomer having a functional group may be selected from the group consisting of methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-vinylpyrrolidone, N-vinylcaprolactam, (meth)acrylamide, N-vinylacetamide, 4-acryloylmorpholine, glycidyl (meth)acrylate, 2-isocyanatoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate, acrylonitrile, and any mixture thereof.

[0082] The radically (co)polymerizable (meth)acrylate-based component (a) of the curable precursor disclosed herein may comprise 1-15 wt%, 2-12 wt%, 3-10 wt%, 4-10 wt%, or even 5-10 wt% of an ethylenically unsaturated monomer having a functional group, the weight percentages being based on the total weight of the (meth)acrylate-based component.

[0083] The curable precursors disclosed herein may further comprise thermally conductive particles (e), which are used as fillers in the curable precursors to improve the thermal conductivity of the cured composition.

[0084] Thermally conductive particles for use herein may be selected from the group consisting of metal oxides, metal nitrides, metal hydroxides, metal particles, coated metal particles, ceramic particles, coated ceramic particles, and any combination or mixture thereof.

[0085] Preferably, the thermally conductive particles are selected from the group consisting of aluminum oxide, aluminum hydroxide, boron nitride, aluminum nitride, silicon nitride, gallium nitride, silicon oxide, magnesium oxide, zinc oxide, zirconium oxide, tin oxide, copper oxide, chromium oxide, titanium oxide, silicon carbide, graphite, magnesium hydroxide, calcium hydroxide, carbon nanotubes, carbon black, carbon fibers, diamond, clay, aluminosilicates, calcium carbonate, barium titanate, potassium titanate, copper, silver, gold, nickel, aluminum, platinum, and any combination or mixture thereof.

[0086] More preferably, the thermally conductive particles are selected from the group consisting of aluminum oxide, aluminum hydroxide, boron nitride, and any combination or mixture thereof.

[0087] Even more preferably, the thermally conductive particles are selected from the group consisting of aluminum oxide, aluminum hydroxide, and any combination or mixture thereof.

[0088] The thermally conductive particles may include primary particles, agglomerates of primary particles, or a combination thereof.

[0089] The thermally conductive primary particles and agglomerates of primary particles may have an isotropic shape, an anisotropic shape, or a combination thereof.

[0090] The thermally conductive primary particles and agglomerates of primary particles may have a spherical shape, a platelet shape, or a combination thereof.

[0091] Exemplary thermally conductive primary particles and agglomerates of primary particles for use herein are described, for example, in EP 3127973(A1) (Wieneke et al.).

[0092] The average particle size of thermally conductive primary particles and aggregates of primary particles (d 50 The average particle diameter (d 50 ) can be measured by laser diffraction.

[0093] Cross-plane thermal conductivity may be of primary importance in some applications, such as, for example, thermally conductive filler applications, in which isotropic thermally conductive particles (e.g., spherical particles) may be preferred because asymmetric fibers, flakes, or platelets may tend to align in the in-plane direction.

[0094] The thermally conductive particles may include thermally conductive particles having a surface functionalization. The surface functionalization of the thermally conductive particles may have a polarity selected from the group consisting of acidic functionality, basic functionality, hydrophobicity, hydrophilicity, and any combination or mixture thereof.

[0095] In one advantageous aspect of the present disclosure, the surface functionalization of the thermally conductive particles comprises a hydrophobic surface functionalization.

[0096] In the context of the present disclosure, the expression "hydrophobic surface functionalization" is intended to denote that the surface of the thermally conductive particles, after suitable surface modification, has little or no affinity for polar substances, in particular water. The expression "hydrophilic surface functionalization" is intended to denote that the surface of the thermally conductive particles, after suitable surface modification, has a relatively high affinity for polar substances, in particular water.

[0097] The thermally conductive particles may further have flame retardant properties or / and electrically insulating properties.

[0098] The curable precursors disclosed herein may comprise 20-95%, 30-90%, 30-80%, 40-90%, 40-80%, 50-90%, 50-80%, 60-90%, or 65-85% by weight of thermally conductive particles, where the weight percentages are based on the total weight of the curable precursor.

[0099] The curable precursors disclosed herein may further comprise a base (f).

[0100] As used herein, "base" refers to an Arrhenius base. Additionally, a "base" refers to a base that, when dissolved in an aqueous solution, converts hydroxides (OH) in the solution. - ) ions.

[0101] The base may be a tertiary amine, or a combination of tertiary amines.

[0102] Tertiary amines have the formula R 1 R 2 R 3 -N, where R 1 , R 2 and R 3 is independently an alkyl group or an aryl group. Suitable tertiary amine bases include, but are not limited to, p-toluidine ethoxylate (synonymous with N,N-bis(2-hydroxyethyl)-p-toluidine), N,N-dimethyl-p-toluidine, N,N-dimethylaniline, N,N-diethylaniline, and diisopropyl p-toluidine.

[0103] The base may function as a polymerization accelerator for the curable precursor.

[0104] The curable precursor may contain, for example, 0.1 to 5 wt %, or 0.1 to 3 wt %, of a base, based on the total weight of the curable precursor.

[0105] In some embodiments of the curable precursors disclosed herein, the curable precursor does not include a base.

[0106] The curable precursors disclosed herein may have a pH value of less than 7. Preferably, the curable precursors may have a pH value of less than 6. The curable precursors may have a pH value of 3-6, or 4-5.

[0107] To measure the pH value of the curable precursor, a pH paper or strip may be wetted with water and the curable precursor may be applied to the pH paper or strip.

[0108] To measure the pH value of the curable precursor, the components of the curable precursor may be dissolved in water, and the pH value may be measured using a pH meter. When measuring the pH of the curable precursor using a pH meter, each water-soluble component of the curable precursor in a percentage in grams may be dissolved in an amount of water corresponding to the difference between the sum of these percentages in grams to 100%, and the pH value of the resulting aqueous solution is measured. Components of the curable precursor that are insoluble in water are not added in the measurement because they do not dissolve in water and cannot contribute to the measurement. "Water-insoluble" should be understood as a component that has a solubility in water of 0.2 g / L or less at 23°C, and "water-soluble component" should be understood as a component that has a solubility in water of more than 0.2 g / L at 23°C. Also, particulate filler materials such as thermally conductive particles are not added in the pH value measurement using a pH meter.

[0109] In some embodiments, the pH value of the curable precursor is less than 7 even when a base (f) is added. For example, if the curable precursor includes a base in an amount of 0.1 to 5 wt %, based on the total weight of the curable precursor, the curable precursor can have a pH value of less than 7.

[0110] Surprisingly, nitroxides have the function of inhibitors and can not only effectively prevent core polymerization despite the presence of acidic compounds in the curable precursor, but also effectively prevent core polymerization when the curable precursor is acidic, i.e., when the pH value of the curable precursor is less than 7.

[0111] The curable precursor may further include additives such as dispersants, antioxidants, flame retardants, or dyes.

[0112] In some embodiments, the curable precursors disclosed herein do not include a urethane (meth)acrylate.

[0113] According to one advantageous aspect of the present disclosure, the curable precursor is (substantially) free of plasticizers, thixotropic agents, silicon-based compounds, halogen-based compounds, isocyanate-based compounds, and any combinations or mixtures thereof.

[0114] According to another advantageous aspect of the present disclosure, the curable precursor is (substantially) free of solvents, in particular organic solvents.

[0115] According to yet another exemplary embodiment of the present disclosure, the curable precursor further comprises an initiator for radical polymerization.

[0116] The term "initiator" is intended to refer to a substance or group of substances capable of starting or initiating or contributing to the curing process of a curable precursor, i.e. capable of starting or initiating or contributing to the radical (co)polymerization of (meth)acrylate-based components.

[0117] The initiators used herein contain free radicals or can generate free radicals. Exemplary initiators for use herein include, but are not limited to, organic peroxides. Organic peroxides include hydroperoxides, ketone peroxides, and diacyl peroxides. Examples of hydroperoxides are cumene hydroperoxide, tert-pentyl hydroperoxide, diisopropylbenzene hydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide. An example of a ketone peroxide is methyl ethyl ketone peroxide. An example of a diacyl peroxide is dibenzoyl peroxide. Examples of other organic peroxides are tert-butyl peroxybenzoate, dicumyl peroxide, 1,3-di-(2-tert-butylperoxyisopropyl)benzene, tert-butylcumyl peroxide, and di-tert-butyl peroxide.

[0118] Preferably, dibenzoyl peroxide is used as the initiator.

[0119] The curable precursor may include, for example, 0.1 to 2 wt %, or 0.1 to 1 wt %, of an initiator, based on the total weight of the curable precursor.

[0120] In one exemplary implementation, the curable precursor of the present disclosure is in the form of a two-part composition having a first part and a second part, the first part and the second part remaining separate prior to combining the two parts to form the cured composition.

[0121] The first part is C1-C 32The composition comprises a radically (co)polymerizable (meth)acrylate-based component comprising a (meth)acrylic acid ester monomer and an ethylenically unsaturated acidic compound, a crosslinker and a nitroxide. The second part comprises an initiator for radical polymerization. With respect to the first part, the core polymerization of the curable precursor is effectively prevented by the nitroxide inhibitor, and the first part can be stored for weeks or months, for example in a 100-200 l drum. Curing can be started by combining the first part with the second part, and despite the stabilization of the first part, rapid curing is possible even at room temperature.

[0122] In an advantageous embodiment of the present disclosure, the two parts of the curable precursor may be mixed in a first part to second part mixing ratio ranging from 10:1 to 1:1, or from 5:1 to 3:1. Preferably, the two parts of the curable precursor may be mixed in a first part to second part mixing ratio of 4:1.

[0123] 1. A method for producing a cured composition from a curable precursor as disclosed herein, the method comprising: providing a curable precursor, the curable precursor comprising: (a) a radically (co)polymerizable (meth)acrylate-based component, (i) C1~C 32 (meth)acrylic acid ester monomer; (ii) an ethylenically unsaturated acidic compound; and A radical (co)polymerizable (meth)acrylate-based component comprising: (b) a crosslinker for the (meth)acrylate based component, comprising at least one acid functional group derived from phosphoric acid and at least one radically (co)polymerizable reactive group; (c) a nitroxide; Including, C1~C 32 providing a curable precursor, in which the (meth)acrylic acid ester monomer (a)(i) does not contain any functional group other than a (meth)acrylic acid ester group, and the ethylenically unsaturated acidic compound (a)(ii) does not contain any acid functional group derived from phosphoric acid; Providing an initiator for the radical polymerization of a curable precursor; mixing a curable precursor and an initiator; curing the mixture of the curable precursor and the initiator; Further disclosed herein is a method comprising:

[0124] In particular, all the specific and preferred aspects relating to the (meth)acrylate based components, crosslinkers, nitroxides and initiators described above in the context of the curable precursor are fully applicable to the above described method.

[0125] The first and second portions of the curable precursor can be extruded from a 2K cartridge or 2K system using a static or dynamic mixer.

[0126] As used herein, "hardening" or "curing" a composition or mixture are used interchangeably and refer to (co)polymerization and / or crosslinking reactions, including chemical (co)polymerization techniques (e.g., chemical reactions that form radicals effective to (co)polymerize radically (co)polymerizable compounds, such as ethylenically unsaturated compounds), involving one or more materials included in the composition.

[0127] The curable precursors disclosed herein are curable without the use of any actinic radiation, especially UV light.

[0128] The curable precursors disclosed herein are curable without the use of any additional thermal energy.

[0129] The curable precursors disclosed herein are curable without the need for expensive catalysts such as platinum.

[0130] Despite the stabilization of the reactive compounds of the curable precursors, such as the (meth)acrylate-based components and the crosslinker, by the nitroxide inhibitors, the curing can be carried out very quickly at room temperature without the need for UV light or high temperatures. After a curing time of only 30 minutes, an adhesive strength (overlap shear strength) of at least 1 MPa can be achieved.

[0131] The cured compositions produced by the methods disclosed herein may be in the form of an adhesive gap filler.

[0132] In the context of the present disclosure, the expression "adhesive gap filler" is intended to denote an adhesive composition used to at least partially fill a spatial gap between a first surface and a second surface. After mixing the first and second parts of the curable precursor, the curable precursor can flow into and fill the spatial gap between the first and second surfaces, and after curing of the curable precursor, the cured composition provides an adhesive bond between the first and second surfaces having good mechanical properties and good adhesive strength. The first surface may be a battery cell of an electric vehicle and the second surface may be a cooling plate. The adhesive gap filler may become a thermally conductive adhesive gap filler by the addition of thermally conductive particles.

[0133] Curing may be carried out at a temperature below 50° C., or at a temperature up to 40° C. or up to 30° C., or at room temperature (23° C.). Preferably, curing is carried out at room temperature (23° C.).

[0134] Typically, curing is carried out for up to 1 hour. Curing may be carried out for up to 45 minutes, or up to 30 minutes. Typically, after 30 minutes of curing time at room temperature (23°C), a cured composition having an adhesive strength of at least 0.7 MPa is obtained. The adhesive strength of the cured composition after 30 minutes of curing time at room temperature (23°C) may be at least 1 MPa, or at least 2 MPa, or at least 3 MPa, depending on the amount of initiator used.

[0135] According to certain advantageous aspects, the curable precursors of the present disclosure are curable at 23° C. with a percentage cure of greater than 90%, greater than 95%, greater than 98%, or even greater than 99% after a cure time of 72 hours or less, 48 ​​hours or less, or even 24 hours or less, depending on the amount of initiator used.

[0136] Cure times can be adjusted as desired depending on the target application and manufacturing requirements.

[0137] Cured compositions produced by the methods disclosed herein may have a thermal conductivity of at least 0.1 W / mK, at least 0.3 W / mK, at least 0.5 W / mK, at least 0.7 W / mK, at least 1.0 W / mK, at least 1.2 W / mK, or at least 1.5 W / mK, as measured according to the test methods described in the Experimental Section.

[0138] The cured compositions produced by the methods disclosed herein may have an overlap shear strength (OLS) of at least 0.5 MPa, at least 2.0 MPa, at least 2.5 MPa, at least 3.0 MPa, at least 3.5 MPa, at least 4.0 MPa, or at least 4.5 MPa, as measured according to the test methods described in the Experimental Section.

[0139] The cured compositions produced by the methods disclosed herein may have an overlap shear strength (OLS) in the range of 0.5 to 30.0 MPa, 2.0 to 8.0 MPa, 2.5 to 8.0 MPa, 2.5 to 7.0 MPa, 3.0 to 7.0 MPa, 3.5 to 6.5 MPa, or 4.0 to 6.0 MPa, as measured according to the test methods described in the Experimental Section.

[0140] The cured composition may have an elongation at break of at least 5%, at least 8%, or at least 10%, as measured according to the test methods described in the Experimental Section.

[0141] The curable precursors and cured compositions made from the curable precursors disclosed herein can be used for adhesive and / or thermal management applications in the automotive industry.

[0142] The above curable precursors and cured compositions may be used for the manufacture of battery modules containing a plurality of battery cells, particularly for use in the automotive industry.

[0143] For embodiments of the curable precursor that include thermally conductive particles, the curable precursor and cured composition may be used as a thermally conductive adhesive for battery applications. EXAMPLES

[0144] Test Method Preparation of test formulations: The specimens for testing the mechanical and thermal behavior are prepared from a 4:1 (volume ratio) mixture of the two components (part A:part B) extruded from a 2K cartridge using a static mixer (standard 3M Gold Quadro nozzle for 50 mL cartridges or SULZER MF 10-18 nozzle for 200 mL cartridges). The preparation of both parts is described below. Within the open time, the resulting paste is applied as a film to the surface of the test panel. The surface of the test specimens (25 mm x 100 mm x 4 mm) (aluminium, grade EN AW2024T3) for the overlap shear strength test is sandblasted before bonding using pure corundum with a grain size of about 135 micrometers. The test specimens are left at ambient room temperature (23°C + / - 2°C, relative humidity 50% + / - 5%) for 7 days. The various performance tests are measured as described below.

[0145] 1. Thermal conductivity test The thermal conductivity of the cured compositions is measured according to ASTM E1461 at 23° C. using Laser Flash Analysis (LFA) using a Light Flash Apparatus LFA 467 HyperFlash® available from Netzsch GmbH, Germany, on samples having a thickness of 2 mm.

[0146] 2. Overlap shear strength (OLS) according to DIN EN 1465 The overlap shear strength is determined according to DIN EN 1465 using a Zwick Z050 tensile tester (commercially available from Zwick GmbH & Co. KG, Ulm, Germany) operating at a crosshead speed of 10 mm / min. For the preparation of the overlap shear strength test assembly, the paste resulting from the mixing of parts A and B is spackled onto one surface of the test panel. The aluminum EN AW2024T3 test panel is sandblasted before bonding. The sample is then covered with a second aluminum strip, forming a 13 mm overlap joint. This ensured the formation of a bond line with a thickness of about 300 micrometers using glass beads with a selected diameter distribution. The overlap joint is then clamped together using two binder clips, and the test assembly is further stored at room temperature for 7 days after bonding and then placed in an air circulating oven at 80° C. for 30 minutes. The samples are either tested directly at room temperature or subjected to aging and then tested. Five samples for each example were measured and the results were averaged and reported in MPa.

[0147] 3. Elongation at break according to DIN EN ISO 527-2-5A The elongation at break measurements are carried out according to DIN ISO 527-2-5A using a Zwick Z050 tensile tester (commercially available from Zwick GmbH & Co. KG, Ulm, Germany) operating at a crosshead speed of 10 mm / min. Films with a thickness of about 2 mm are prepared according to the procedure described above. Five samples with a dogbone shape are punched out according to the geometry of DIN ISO 527-2-5A (dimensions 25 mm x 4 mm x 2 mm) and used for further mechanical testing. Measurements are carried out for each sample, the results are averaged and reported as a percentage for the elongation at break.

[0148] 4.Shore A hardness according to DIN EN ISO 868 Shore A hardness measurements are performed according to DIN EN ISO 868 using a ZwickRoell 3115 (commercially available from Zwick GmbH & Co. KG, Ulm, Germany). Films with a thickness of approximately 1 mm are prepared according to the procedure described above. Three samples are used for the Shore A hardness test. Measurements are performed on each sample and the results are averaged and reported.

[0149] 5.Viscosity measurement The viscosity of the test samples is measured at 20 °C using an Anton Paar rheometer MCR 302 using RheoCompass software from Anton Paar. The measurements are performed over a period of 0.1 to 5 s -1 The experiment was carried out using a frequency sweep at a shear rate of 0.1 s -1 So we take 90 measurement points, one every 2 seconds, and -1 So we take 20 measurement points, one every 2 seconds, and -1 So, take 20 measurement points, one every 1 second, and measure for 5 seconds. -1 So, 40 measurement points were taken, one every 0.5 seconds.

[0150] raw materials In the examples, the following raw materials are used:

[0151] 2-Ethylhexylacrylate (2-EHA) is an acrylic acid ester monomer available from BASF AG, Germany.

[0152] Acrylic acid (AA) is a monomer available from BASF AG, Germany.

[0153] Diol-6000-DMA is a dimethacrylate polyether oligomer having a number average molecular weight of about 6000 g / mol and is available from 3M Espe GmbH, Germany.

[0154] GLP is a dimethacrylate crosslinker derived from phosphoric acid and is available from 3M Espe GmbH, Germany.

[0155] Cyclohexyl methacrylate (CHMA) is a methacrylic acid ester monomer available from BASF AG, Germany.

[0156] 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-OH-TEMPO, TEMPOL) is a nitroxide available from Evonik Industries AG, Germany.

[0157] Martoxid™ 2320 is an aluminum oxide based thermally conductive filler available from Martinswerk, Germany.

[0158] BF083 is an aluminum hydroxide based thermally conductive and flame retardant filler available from Nikkeikin (Japan).

[0159] B53 is an aluminum hydroxide based flame retardant and thermally conductive filler available from Nikkeikin Co., Ltd. (Japan).

[0160] SpaceRite S-11 is an aluminum hydroxide based flame retardant and thermally conductive filler available from JM Huber Corporation, New Jersey, USA.

[0161] Martinal™ 2550 is an aluminum hydroxide based thermally conductive and flame retardant filler available from Martinswerk, Germany.

[0162] Martinal™ 2590 is an aluminum hydroxide based thermally conductive and flame retardant filler available from Martinswerk, Germany.

[0163] Martinal ON908 is an aluminum hydroxide based thermally conductive and flame retardant filler available from Martinswerk, Germany.

[0164] Apyral 200SM is an aluminum hydroxide based thermally conductive and flame retardant filler available from Nabaltec, Germany.

[0165] Pergaquick A150 PM is a basic p-toluidine ethoxylate and is available from Pergan GmbH, Germany.

[0166] BYK-W 9010 is a dispersing agent and is available from BYK-Chemie GmbH, Germany.

[0167] DISPERBYK-145 is a dispersing agent and is available from BYK-Chemie GmbH, Germany.

[0168] Irganox 1076 is an antioxidant and is available from BASF, Germany.

[0169] Irgafos 168 is an antioxidant and is available from BASF, Germany.

[0170] 4-Methoxyphenol (MEHQ) is an inhibitor and is obtained from Sigma-Aldrich, Germany.

[0171] Alpha methyl styryl polyurea resin (AMSPU) is an α-methylstyrene functional polyether oligomer with urea linkages, used to dilute the initiator in the second part of the curable precursor. The α-methylstyrene functional oligomer with urea linkages was prepared as follows: 120 g (0.6 moles) of 3-isopropenyl-α,α-dimethylbenzyl isocyanate (available as TMI from Cytec Industries, West Peterson, NJ, USA) and 600 g (0.6 amine equivalents) of amine-terminated polyether (D2000, a difunctional amine-terminated polyether with a nominal reported MW of 2000, available as Jeffamine™ D2000 from Huntsman Chemical Co., Houston, TX, USA) were combined in a glass container with stirring at room temperature and allowed to stand overnight at room temperature. Infrared spectroscopy (IR) indicated complete reaction by disappearance of the isocyanate band at 2265 cm-1. The calculated molecular weight of the α-methylstyrene functional oligomer is 2460 g / mol.

[0172] Irgazin Red L 3670 HD is a red pigment and is available from BASF AG, Germany.

[0173] Peroxan BP-Paste 50 PF-1 is a dibenzoyl peroxide, initiator for polymerization, available from Pergan GmbH, Germany.

[0174] Examples 1 to 5 (EX1 to EX5) and Comparative Examples 1 and 2 (CEX1 and CEX2) For Examples 1 to 5 and Comparative Example 1, curable precursors were prepared having the formulations shown in Table 1. The formulations in Table 1 represent the first part (Part A) of the two-component formulation of the curable precursor.

[0175] The curable precursors are prepared by combining the raw materials from the list of materials in Table 1 in a speed mixer (DAC 600.2 VAC-P available from Hauschild Engineering, Germany) with stirring at 2000 rpm for 90 seconds until a homogenous mixture is obtained. The materials are then slightly degassed to avoid trapped air. The acrylic ester monomer, ethylenically unsaturated acidic compound, crosslinker and nitroxide are added first, followed by the polyether oligomer, various thermally conductive particles and other additives in successive steps. Comparative Example 1 does not contain any nitroxide. For each composition of the curable precursors listed in Table 1, 100 g was prepared (Part A). [Table 1]

[0176] The stability of the curable precursor (Part A) for core polymerization was tested using glass containers since glass containers have limited oxygen diffusion. Before filling into the glass containers, the curable precursor material was degassed in a Speedmixer for 1:30 min under vacuum (approximately 900 mbar). The glass containers were filled completely with the material (52.5 g of material in a 25 ml glass container), taking care to ensure no air bubbles in the material to ensure a low oxygen atmosphere. This experimental setup simulates the situation in the middle of a drum with a volume of 100-200 liters completely filled with material. For each formulation, three glass containers were filled.

[0177] The filled glass containers were stored at different temperatures (50°C, 65°C and 80°C) for accelerated aging of the test samples. [Table 2]

[0178] As can be seen from Table 2, the comparative example without the addition of 4-OH-TEMPO (CEX1) was already completely cured after 3 days at 65° C. Small amounts of 4-OH-TEMPO (Example 1) prevent core polymerization but show a viscosity increase after 3 days of storage at 65° C. The use of 0.002 wt. % or more of 4-OH-TEMPO stabilizes the formulations for a minimum of 5 days at 65° C. (Examples 2-5).

[0179] For Examples 1 to 5, the pH value of the curable precursor was measured by dissolving the water-soluble components of the curable precursor (i.e., components with a water solubility of more than 0.2 g / L at 23° C.) in water and measuring the pH value of the aqueous solution. For the measurement, 0.5 g of acrylic acid, 0.65 g of GLP, and 0.42 g of Pergaquick A150 PM were dissolved in 98.43 g of water, and the pH value of the aqueous solution was measured using a pH meter. The pH value was less than 3.

[0180] Example 6 (EX6) and Comparative Example 2 (CEX2) For Example 6 and Comparative Example 2, a first portion of a two-component formulation of curable precursor having the formulation composition shown in Table 1 is prepared as described above for Examples 1-5. Samples for testing core polymerization stability are prepared as described above for Examples 1-5.

[0181] For Example 6 and Comparative Example 2, the first part (Part A) and the second part (Part B) of the two-component composition of the curable precursor are prepared separately by combining the raw materials from the list of materials in Table 1 (Part A) and Table 3 (Part B) in a speed mixer (DAC 600.2 VAC-P available from Hauschild Engineering, Germany) with stirring at 2000 rpm for 90 seconds until a homogenous mixture is obtained. The materials are then slightly degassed to avoid trapped air. For Part A, the acrylic ester monomer, ethylenically unsaturated acidic compound, crosslinker and nitroxide are added first, followed by the polyether oligomer, various thermally conductive particles and other additives in successive steps. The initiator for the radical polymerization is only present in Part B. For Part B, the alpha methylstyryl polyurea resin is added first, followed by the various thermally conductive particles, and finally the peroxide initiator. During mixing, the temperature of the mixture should not exceed 40°C. For each of the curable precursor compositions listed in Table 1 (Part A) and Table 3 (Part B), a first portion of 100 g and a second portion of 100 g were prepared.

[0182] The two parts are then loaded into a 2K cartridge with a volume ratio of Part A:Part B=4:1, and the mixture is applied to the surface of the above test panel. In Tables 1 and 3, all concentrations are shown in weight percent. Comparative Example CE2 does not contain any nitroxide.

[0183] The overlap shear specimens, dog-bone shaped specimens for elongation at break, and specimens for thermal conductivity and hardness measurements are cured at room temperature for 7 days. Measurements are performed as described above in the Test Methods section.

[0184] The test results are shown in Table 4. [Table 3] [Table 4]

[0185] As can be seen from Table 4, Example 6 (0.003 wt% 4-OH-TEMPO added) performs similarly to Comparative Example 2 (no 4-OH-TEMPO added), but shows greatly increased stability with respect to core polymerization. In Comparative Example 2, core polymerization was observed in less than 24 hours at 50° C. and in less than 9 hours at 80° C. (the composition was fully polymerized in both cases), whereas in Example 6, core polymerization was not observed after 21 days at 50° C. and after 3 days at 80° C.

[0186] For Example 6, oscillatory rheology was measured to determine the cure rate. The gel point (i.e., the point at which the storage and loss moduli are equal) is approximately 9 minutes after the two parts of the two-part formulation are combined. This indicates a fast cure time at room temperature, even with 0.003 wt% 4-OH-TEMPO.

[0187] Examples 7 and 8 (EX7 and EX8) and Comparative Example 3 (CEX3) For Examples 7 and 8 and Comparative Example 3, the first part (Part A) and the second part (Part B) of the two-component formulation of the curable precursor are prepared separately by combining the raw materials from the list of materials in Table 5 (Part A) and Table 6 (Part B) in a planetary mixer and mixing until a homogenous mixture is obtained. The materials are then slightly degassed to avoid trapped air. For Part A, the acrylic ester monomer and polyether oligomer and nitroxide are added first, followed by the various thermally conductive particles and other additives in successive steps. Finally, the ethylenically unsaturated acidic compound and crosslinker are added, followed by the base after mixing. The initiator for the radical polymerization is only present in Part B. For Part B, the alpha methylstyryl polyurea resin is added first, followed by the various thermally conductive particles, and finally the peroxide initiator. During mixing, the temperature of the mixture should not exceed 40°C. For each curable precursor composition listed in Table 5 (Part A) and Table 6 (Part B), a first portion of 500 L (1050 kg) and a second portion of 300 L (630 kg) were prepared.

[0188] For Example 8 and Comparative Example 3, samples for testing core polymerization stability at 50° C. and 80° C. are prepared from the first part (Part A) of the curable precursor described above for Examples 1-5.

[0189] The test results are shown in Table 7. [Table 5] [Table 6] [Table 7]

[0190] As can be seen from Table 7, Example 8 (0.003 wt% 4-OH-TEMPO added) performs similarly to Comparative Example 3 (no 4-OH-TEMPO added), but shows greatly increased stability with respect to core polymerization. In Comparative Example 3, core polymerization was observed in less than 24 hours at 50° C. and in less than 9 hours at 80° C. (the composition was fully polymerized in both cases), whereas in Example 8, core polymerization was not observed after 21 days at 50° C. and after 3 days at 80° C.

[0191] In Comparative Example 3, core polymerization was observed in a drum filled with 150 L of the composition at room temperature (23° C.) in less than two weeks (core polymerization in the center of the drum), whereas in Example 8, core polymerization was not observed in a drum filled with 150 L of the composition after storage at room temperature for six months.

Claims

1. A curable precursor of an adhesive composition, wherein the curable precursor comprises (a) a radically (co)polymerizable (meth)acrylate-based component, wherein (i) C １ ~ C ３２ a (meth)acrylic acid ester monomer, and (ii) an ethylenically unsaturated acidic compound, and a radically (co)polymerizable (meth)acrylate-based component containing the same, (b) a crosslinking agent for the (meth)acrylate-based component, containing at least one acid functional group and at least one radically (co)polymerizable reactive group derived from phosphoric acid, (c) a nitroxide, and Said C １ -C ３２ The curable precursor, wherein the (meth)acrylic acid ester monomer (a)(i) does not contain a functional group other than the (meth)acrylic acid ester group, and the ethylenically unsaturated acidic compound (a)(ii) does not contain an acid functional group derived from phosphoric acid.

2. The above-mentioned C １ -C ３２ The curable precursor according to claim 1, wherein the (meth)acrylate monomer is selected from the group consisting of isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, methyl (meth)acrylate, benzyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and any mixture thereof.

3. The curable precursor according to claim 1, wherein the ethylenically unsaturated acidic compound comprises monomers, oligomers, and polymers having ethylenic unsaturation and acid and / or acid precursor functionality.

4. The curable precursor according to claim 1, wherein the nitroxide is selected from the group consisting of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), its derivatives, and combinations thereof.

5. The curable precursor according to claim 1, wherein the nitroxide is 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL).

6. (d) a polyether oligomer having a number average molecular weight of at least 2000 g / mol and containing at least one radically (co)polymerizable reactive group, wherein the number average molecular weight is determined by gel permeation chromatography (GPC), and further comprising the polyether oligomer.

7. The curable precursor according to claim 1, wherein the radically (co)polymerizable (meth)acrylate-based component (a) further comprises (iii) An ethylenically unsaturated monomer having a functional group, wherein the C of the radical (co)polymerizable (meth)acrylate component (a) １ ~C ３２ An ethylenically unsaturated monomer copolymerizable with the (meth)acrylic acid ester monomer (i) and the ethylenically unsaturated acidic compound (ii) and further comprising the same.

8. (e) thermally conductive particles and further comprising the thermally conductive particles.

9. (f) a base and further comprising the base.

10. The curable precursor according to claim 9, wherein the base is a tertiary amine or a combination of tertiary amines.

11. The curable precursor according to claim 1, wherein the curable precursor does not contain a base.

12. The curable precursor according to claim 1, wherein the curable precursor further comprises an initiator for radical polymerization.

13. A method for producing a cured composition from the curable precursor according to any one of claims 1 to 12, wherein the method comprises providing a curable precursor, wherein the curable precursor comprises (a) A radical (co)polymerizable (meth)acrylate-based component, (i) C １ ~C ３２ a (meth)acrylate monomer, and (ii) An ethylenically unsaturated acidic compound, A radical (co)polymerizable (meth)acrylate-based component containing (b) A crosslinking agent for the (meth)acrylate-based component, containing at least one acid functional group and at least one radical (co)polymerizable reactive group derived from phosphoric acid, (c) A nitroxide, Containing, Said C １ to C ３２ Providing a curable precursor in which the (meth)acrylic acid ester monomer (a)(i) does not contain a functional group other than the (meth)acrylic acid ester group and the ethylenically unsaturated acidic compound (a)(ii) does not contain an acid functional group derived from phosphoric acid. Providing an initiator for radical polymerization of the curable precursor, Mixing the curable precursor and the initiator, Curing a mixture of the curable precursor and the initiator, A method comprising.

14. The method according to claim 13, wherein the curing is carried out at a temperature below 50 °C, preferably at room temperature (23 °C).

15. Use of the curable precursor according to claim 1 for adhesive applications and / or thermal management applications in the automotive industry.