Anti-oxidation polymerization-inhibition high-temperature-resistant UV curing adhesive and preparation method thereof

Abstract

The invention provides an anti-oxidation polymerization-inhibition high-temperature-resistant UV curing adhesive and a preparation method thereof. The anti-oxidation polymerization-inhibition high-temperature-resistant UV curing adhesive contains polyfunctional group mercaptan, tertiary amine and fumed silica. The anti-oxidation polymerization-inhibition high-temperature-resistant UV curing adhesive is prepared from the following raw materials: 40 to 60 parts of acrylate, 20 to 40 parts of acrylate monomer, 10 to 30 parts of polyfunctional group mercaptan, 1 to 5 parts of photoinitiator, 1 to 5 parts of tertiary amine, 1 to 10 parts of fumed silica and 1 to 3 parts of additive. On the basis of a'thiol-ene 'click reaction of thiol and acrylate, the oxygen inhibition effect of the curing adhesive is improved, acrylic acid chain type free radical polymerization is carried out, molecular chains are closely crosslinked, the structural strength and mechanical property of the curing adhesive are improved, and the curing adhesive is more resistant to high temperature. In the curing adhesive system, tertiary amine has an inhibition effect on oxygen inhibition, and fumed silica is used as a filler to enhance the mechanical strength and further improve the mechanical properties at high temperature. The anti-oxidation polymerization-inhibition high-temperature-resistant UV curing adhesive disclosed by the invention has the characteristics of rapid curing, good surface dryness, excellent mechanical properties, high temperature resistance and the like.

Description

Technical Field

[0001] This invention belongs to the field of UV-curable adhesives and relates to an antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive and its preparation method. Background Technology

[0002] UV-curable adhesives are widely used in electronics, automotive, and new energy industries due to their advantages such as rapid curing, strong adhesion, environmental friendliness, low energy consumption, and no solvent evaporation. Currently, common UV curing systems on the market are mainly divided into three categories: free radical polymerization systems, cationic polymerization systems, and free radical-cationic co-initiation systems. Among them, free radical-initiated acrylate systems have the fastest polymerization speed and the easiest performance to adjust, making them the most widely used adhesives across various industries.

[0003] However, acrylates still have some limitations in practical applications. On the one hand, acrylate systems are inevitably affected by oxygen inhibition, which refers to the phenomenon where surfaces exposed to air are difficult to cure due to the inhibitory effect of oxygen, resulting in a sticky, non-drying state where the lower layer of the colloid has cured while the surface remains uncured. Essentially, in free radical polymerization, the chain-growing free radicals combine with oxygen, thus losing their reactivity. Oxygen inhibition not only prolongs the curing time but may also affect the properties of the cured surface layer, such as hardness, abrasion resistance, and scratch resistance.

[0004] Patent CN116144273A discloses a method for preparing a low-volatile UV adhesive for optical lenses. This adhesive uses acrylic monomers and polythiols for polymerization, avoiding the adverse effects of oxygen inhibition and improving the conversion rate of the polymerized monomers. This reduces VOC emissions during the curing process, resulting in a highly reactive surface and a clean, non-sticky feel after curing. Although the adhesive exhibits some anti-oxidative polymerization properties through the addition of thiols, the UV adhesive system lacks sufficient strength, posing a risk of mechanical property failure at high temperatures. Furthermore, polythiols are prone to self-polymerization above 30°C, affecting practical application.

[0005] On the other hand, compared with adhesives such as epoxy resin and silicone, acrylates are usually more sensitive to temperature due to their weaker bond energy and are prone to failure at high temperatures, resulting in a significant reduction in the mechanical properties of the cured adhesive. Over time, this will challenge the reliability of the bonded parts.

[0006] Therefore, there is still a need in the field to improve the heat resistance and high temperature resistance of acrylate systems, while improving their oxygen inhibition effect, so that they can maintain their mechanical properties without being affected while rapidly polymerizing, thereby effectively solving the current problems in the application of acrylate UV-curable adhesives. Summary of the Invention

[0007] This invention addresses the aforementioned problems in existing technologies by proposing an antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive and its preparation method. This invention discovers that the thiol group in thiol undergoes a "thiol-ene" click reaction with acrylate, which improves the oxygen inhibition effect. Furthermore, the photoinitiated thiol-ene click reaction and the chain-like free radical polymerization of acrylic acid occur simultaneously, resulting in tight cross-linking of the molecular chains, enhancing the structural strength and mechanical properties of the cured adhesive, and improving its high-temperature resistance. This invention also discovers that the tertiary amine in the system also inhibits oxygen polymerization. As a hydrogen donor, the tertiary amine reacts with peroxy radicals generated from oxygen to form new aminoalkyl radicals, which can re-initiate the polymerization of acrylate monomers. Therefore, it consumes oxygen and forms a synergistic effect with the thiol, further improving the oxygen inhibition of the system. Finally, fumed silica can be used as a filler to enhance mechanical strength, further improving mechanical properties at high temperatures. Therefore, the antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive of this invention contains multifunctional thiols, tertiary amines, and fumed silica, and features rapid curing, good surface drying, excellent mechanical properties, and high-temperature resistance.

[0008] Specifically, one aspect of the present invention provides an antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive, wherein the raw material components of the UV-curable adhesive (in parts by weight) include: 40-60 parts of polyurethane acrylate, 20-40 parts of acrylate monomer, 10-30 parts of polyfunctional thiol, 1-5 parts of photoinitiator, 1-5 parts of tertiary amine, 1-10 parts of fumed silica, and 1-3 parts of additives.

[0009] In one or more embodiments, the polyurethane acrylate is an aliphatic polyurethane acrylate.

[0010] In one or more embodiments, the polyurethane acrylate has a viscosity of 800-2000 cps / 60°C, an acid value of < 5.0 mg KOH / g, a weight-average molecular weight of 500-2000, and a solid content of ≥ 90%.

[0011] In one or more embodiments, the polyurethane acrylate is an aliphatic polyurethane acrylate with a viscosity of 800-2000 cps / 60℃, an acid value of < 5.0 mg KOH / g, a weight-average molecular weight of 500-2000, and a solid content of ≥ 90%.

[0012] In one or more embodiments, the structure of the acrylate monomer is shown in Formula I: , Where R1 is H or C 1-6 Alkyl group, where R2 is H or C 1-10 Alkyl group, R3 is C 1-12 Alkyl, Borneol, Isobenol, Tetrahydrofurfural, Hydroxyl-substituted C 1-4 alkyl, or The wavy line indicates the position where R3 connects to the other parts of the compound of formula I.

[0013] In one or more embodiments, R1 in Formula I is H, methyl, or ethyl.

[0014] In one or more embodiments, R2 in Formula I is H, methyl, or ethyl.

[0015] In one or more embodiments, R3 in Formula I is lauryl, isobornyl, tetrahydrofurfuryl, (CH3)2CH(CH2)5-, CH2OHCH2CH2-, CH2OHCH2-, or The wavy line indicates the position where R3 is connected to the other parts of the compound of formula I.

[0016] In one or more embodiments, the acrylate monomer is selected from one or a mixture of two or more of cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, isooctyl acrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, isocyanate ethyl methacrylate, isobornyl acrylate, and tetrahydrofurfuryl acrylate.

[0017] The thiol group in thiols can undergo a "thiol-alkene" click reaction with the double bond, resulting in rapid polymerization that is unaffected by oxygen and can improve the oxygen inhibition efficiency of the system.

[0018] In one or more embodiments, the polyfunctional thiol is in the form of R-(SH). n This indicates that R is selected from any substituted C. 6-14 Aryl or tris(2-propoxyethyl)isocyanurate group, where n is 2, 3 or 4.

[0019] In one or more embodiments, the polyfunctional thiol is selected from one or a mixture of two or more of tris-2-(3-mercaptopropoxy)ethyl isocyanurate, 1,4-benzenedimethylthiol, biphenyl-4,4'-dithiol, and 2,5-diamino-1,4-benzenedithiol.

[0020] In one or more embodiments, the polyfunctional thiol is selected from one or a mixture of two or more of 1,4-benzenedimethylthiol, biphenyl-4,4'-dithiol, and 2,5-diamino-1,4-benzenedithiol.

[0021] In one or more embodiments, the photoinitiator is one or more of benzoin dimethyl ether, benzophenone, 2-hydroxymethylphenylacetone, 1-hydroxycyclohexylphenyl ketone and thioxanthone.

[0022] In one or more embodiments, the thioxanthonone is selected from one or both of 2,4-diethylthioxanthonone and 2-isopropylthioxanthonone.

[0023] In one or more embodiments, the benzoin dimethyl ether, benzophenone, and thioxanthone are mixed in any proportion.

[0024] Fumed silica can be used as a filler to enhance the mechanical strength of a system, improve its high-temperature resistance, and enhance its mechanical properties at high temperatures. In one or more embodiments, the particle size of the fumed silica is 7 nm-20 nm.

[0025] Tertiary amines are sensitive to oxygen and readily capture reactive oxygen free radicals in the air, ensuring that the chain growth process in the acrylate UV curing system is not affected by oxygen, thus inhibiting surface oxygen polymerization.

[0026] In one or more embodiments, the structure of the tertiary amine is shown in Formula II: , Among them, R4, R5, and R6 are each independently C 1-6 Alkyl, hydroxyl substituted C 1-6 Alkyl, phenyl or C 1-6 Alkoxycarbonyl-substituted phenyl groups.

[0027] In one or more embodiments, the tertiary amine is selected from one or more of triethylamine, triethanolamine, N,N-dimethylaniline and N,N-dimethylaminobenzoate in any proportion.

[0028] In one or more embodiments, the adjuvant comprises a coupling agent and a defoamer, wherein the mass ratio of the coupling agent to the defoamer is (1-5):1.

[0029] In one or more embodiments, the mass ratio of the coupling agent to the defoamer is (2-4):1.

[0030] In one or more embodiments, the coupling agent is any one of the silane coupling agents KH550, KH560, and KH570.

[0031] In one or more embodiments, the defoamer is polysiloxane emulsion defoamer N-10.

[0032] Another aspect of the present invention provides a method for preparing an antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive, the method comprising the following steps: (1) Mix the polyurethane acrylate, acrylate monomer, multifunctional thiol, photoinitiator, tertiary amine, fumed silica, and additives; and (2) Vacuum defoaming.

[0033] In one or more embodiments, step (1) mixing is performed by a dual-star dynamic mixing mixer.

[0034] In one or more embodiments, the mixing rate of step (1) is 600 r / min-1000 r / min and the mixing time is 0.5 h-2 h.

[0035] In one or more embodiments, the vacuum degree of step (2) for vacuum defoaming is -0.09 MPa to -0.06 MPa.

[0036] In one or more embodiments, the product obtained by vacuum defoaming in step (2) is sealed and packaged, and stored in a dark and low-temperature environment.

[0037] Another aspect of the present invention provides an application of an antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive: (1) Application of multifunctional thiols, tertiary amines and optional fumed silica in improving the curing rate, surface dryness, mechanical properties and / or high temperature resistance of UV-curable adhesives; (2) Application of multifunctional thiols, tertiary amines and optional fumed silica in the preparation of UV-curable adhesives; Wherein, the polyfunctional thiol is as described in any of the polyfunctional thiools herein, and the tertiary amine is as described in any of the tertiary amines herein. Detailed Implementation

[0038] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used herein are explained and defined in general terms below. Unless otherwise specified, all technical and scientific terms used herein have the common meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0039] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0040] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0041] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0042] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0043] In this article, the sum of the percentages of all components in the composition is 100%.

[0044] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope of this invention.

[0045] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0046] This invention employs a UV-curable adhesive containing multifunctional thiols, tertiary amines, and fumed silica. Through a "thiol-olefin" click reaction between oxygen-independent thiol groups and acrylates, chain-like free radical polymerization of acrylic acid, oxygen consumption by the tertiary amine initiating acrylate monomer polymerization and a synergistic effect with the thiol, and the use of fumed silica as a filler to enhance mechanical strength, the invention effectively overcomes the effects of oxygen inhibition, improving the structural strength of the cured adhesive. This results in an oxygen-resistant, high-temperature resistant UV-curable adhesive with characteristics such as rapid curing, good surface drying, and excellent mechanical properties. The UV-curable adhesive maintains high mechanical properties after high-temperature aging, reducing the risk of adhesive failure and delamination at high temperatures. Furthermore, its good surface drying properties make it a promising candidate for applications in 3D printing, photovoltaic new energy, and other fields.

[0047] Antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive

[0048] The raw material components (by weight) of the antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive of the present invention include: 40-60 parts of polyurethane acrylate, 20-40 parts of acrylate monomer, 10-30 parts of polyfunctional thiol, 1-5 parts of photoinitiator, 1-5 parts of tertiary amine, 1-10 parts of fumed silica, and 1-3 parts of additives.

[0049] In this invention, polyurethane acrylates conventionally used in photocurable adhesives are all applicable. The molecule of polyurethane acrylate (PUA) contains three chemically structured segments: urethane blocks formed from diisocyanates, a main chain formed from polyols, and chain ends formed from acrylates. In some embodiments, the polyurethane acrylate suitable for this invention is an aliphatic polyurethane acrylate. In some embodiments, the polyurethane acrylate has a viscosity of 800-2000 cps / 60°C, an acid value < 5.0 mg KOH / g, a functionality of 2-6, a weight-average molecular weight of 500-2000, and a solid content ≥90%. An exemplary polyurethane acrylate may be RU-2021B-2 material from Ruicheng New Materials.

[0050] In some embodiments, the weight percentage of polyurethane acrylate is 40-60 parts, for example 40-50 parts, 45-55 parts, 50-60 parts, such as 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, or any two of the above values ​​forming a range.

[0051] In this paper, the structure of the acrylate monomer is shown in Formula I: , Where R1 is H or C 1-6 Alkyl group, where R2 is H or C 1-10 Alkyl group, R3 is C 1-12 Alkyl, Borneol, Isobenol, Tetrahydrofurfural, Hydroxyl-substituted C 1-4 alkyl, or The wavy line indicates the position where R3 connects to the other parts of the compound of formula I.

[0052] Preferably, R1 in Formula I is H, methyl, or ethyl.

[0053] Preferably, R2 in Formula I is H, methyl, or ethyl.

[0054] Preferably, in Formula I, R3 is lauryl, isobornyl, tetrahydrofurfuryl, (CH3)2CH(CH2)5-, CH2OHCH2CH2-, CH2OHCH2-, or The wavy line indicates the position where R3 is connected to the other parts of the compound of formula I.

[0055] In some embodiments, the acrylate monomer is selected from one or a mixture of two or more of cyclotrimethylolpropane methyl acetal acrylate, lauryl acrylate, isooctyl acrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, isocyanate ethyl methacrylate, isobornyl acrylate, and tetrahydrofurfuryl acrylate.

[0056] In some embodiments, the acrylate monomer weight percentage is 20-40 parts, for example 20-25 parts, 20-30 parts, 20-35 parts, 25-30 parts, 25-35 parts, 30-40 parts, 35-40 parts, such as 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, or any two of the above values ​​as the endpoints forming a range.

[0057] In this article, the thiol group refers to the -SH group, and a polyfunctional thiol refers to a compound with ≥ 2 thiol groups in a single molecule. An exemplary polyfunctional thiol can be R-(SH). n This indicates that R can be selected from any arbitrarily substituted C. 6-14 Aryl or tris(2-propoxyethyl)isocyanurate group, where n is 2, 3, or 4. The aryl group can be phenyl, naphthyl, or biphenyl, optionally surrounded by 1-3 groups selected from amino (NH2) and C. 1-4 Alkyl substituents. Exemplary polyfunctional thiols include, but are not limited to, tris-2-(3-mercaptopropoxy)ethyl isocyanurate, 1,4-benzenedimethylthiol, biphenyl-4,4'-dithiol, and 2,5-diamino-1,4-benzenedimethylthiol. In some embodiments, preferred polyfunctional thiols are 1,4-benzenedimethylthiol, biphenyl-4,4'-dithiol, and 2,5-diamino-1,4-benzenedimethylthiol.

[0058] In some implementations, the weight percentage of the polyfunctional thiol is 10-30 parts, for example 10-15 parts, 10-20 parts, 10-25 parts, 15-20 parts, 15-25 parts, 20-30 parts, 25-30 parts, such as 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, or any two of the above values ​​as the endpoints of the range.

[0059] In this document, any photoinitiators known in the art for use with photocurable adhesives (especially UV-curable adhesives) may be used in this invention. Exemplary photoinitiators include, but are not limited to, one or more mixtures of benzoin dimethyl ether, benzophenone, 2-hydroxymethylphenylacetone, 1-hydroxycyclohexylphenyl ketone, and thioxanthone.

[0060] In some embodiments, the thioxanthone is selected from one or both of 2,4-diethylthioxanthone and 2-isopropylthioxanthone.

[0061] In some implementations, the photoinitiator is expressed as a weight percentage of 1-5 parts, such as 1-3 parts, 2-5 parts, 3-5 parts, or a range formed by using 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, or any two of the above values ​​as endpoints.

[0062] In this paper, tertiary amines are compounds containing tertiary amine structures. Tertiary amines are sensitive to oxygen and readily capture reactive oxygen free radicals in the air, ensuring that the chain growth process in the acrylate UV curing system is not affected by oxygen, thus inhibiting surface oxygen polymerization. The structure of the tertiary amine of this invention is shown in Formula II below: , Among them, R4, R5, and R6 are each independently C 1-6 Alkyl, hydroxyl substituted C 1-6 Alkyl, phenyl or C 1-6 Alkoxycarbonyl-substituted phenyl groups. Exemplary tertiary amines include, but are not limited to, triethylamine, triethanolamine, N,N-dimethylaniline, and isoamyl N,N-dimethylaminobenzoate. In some embodiments, preferred tertiary amines are one or a mixture of two of triethanolamine and isoamyl N,N-dimethylaminobenzoate.

[0063] In some implementations, the weight percentage of the tertiary amine is 1-5 parts, for example 1-3 parts, 2-5 parts, 3-5 parts, such as 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, or any two of the above values ​​as the endpoints forming a range.

[0064] In this paper, fumed silica, a nanoscale powder particle, is commonly used as a filler in UV-curable adhesives. Through the surface effect and network structure of the nanoparticles, it achieves reinforcement and thixotropic regulation, enhances high-temperature resistance, and improves the mechanical properties of the cured adhesive at high temperatures. Various types of fumed silica known in the art can be used to implement this invention.

[0065] In some embodiments, the particle size of fumed silica is 7 nm to 20 nm, for example 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, or a range formed with any two of the above values ​​as endpoints.

[0066] In some implementations, the weight percentage of fumed silica is 1-10 parts, for example 1-3 parts, 2-5 parts, 3-5 parts, 1-5 parts, 3-8 parts, 3-10 parts, 5-10 parts, 8-10 parts, such as 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, or any two of the above values ​​as the endpoints forming a range.

[0067] In this invention, the additive is a mixture of coupling agent and defoamer. The additive is used to improve the stability and workability of the cured adhesive. The mass ratio of coupling agent to defoamer in the additive is (1-5):1. In some preferred embodiments, the mass ratio of coupling agent to defoamer is (2-4):1, which can be 2:1, 3:1, or 4:1. The defoamer is used to eliminate air bubbles generated during the manufacturing and use of the cured adhesive, preventing pinholes and other problems. In some embodiments, the defoamer is polysiloxane emulsion defoamer N-10. The coupling agent can improve the interfacial bonding force between the adhesive and the bonded material, thereby improving bond strength, weather resistance, and long-term stability. The coupling agent used in this invention is a silane coupling agent. In some embodiments, the coupling agent is any one of silane coupling agents KH550, KH560, and KH570.

[0068] In some implementations, the weight percentage of the adjuvant is 1-3 parts, for example 1-2 parts, 2-3 parts, such as 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, or any two of the above values ​​as the endpoints forming a range.

[0069] In some implementations, the raw materials of the UV-curable adhesive described herein include: (1) Polyurethane acrylate, which is 40-60 parts by weight of aliphatic polyurethane acrylate, with a viscosity of 800-2000 cps / 60℃, acid value < 5.0 mg KOH / g, functionality of 2-6, weight-average molecular weight of 500-2000, and solid content ≥ 90%; (2) Acrylate monomers, namely isobornyl acrylate, hydroxyethyl acrylate and / or tetrahydrofurfuryl acrylate, in total of 20-40 parts by weight; (3) Multifunctional thiols, namely 1,4-benzenedimethylthiol, 2,5-diamino-1,4-benzenedithiol and / or biphenyl-4,4'-dithiol, in total of 10-15 parts by weight. (4) Photoinitiator, which is benzoin dimethyl ether, 2,4-diethylthioxanthrone and / or benzophenone, in a total amount of 1-2 parts by weight; (5) Tertiary amines, namely isoamyl N,N-dimethylaminobenzoate and / or triethanolamine, in total of 1-3 parts by weight; (6) Fumed silica, 3-7 parts by weight; (7) Additives, namely coupling agent KH550, KH560 or KH570 and polysiloxane emulsion defoamer N-10, the total amount of which is 1-2 parts by weight, and the mass ratio of coupling agent to defoamer is (2-4):1.

[0070] Preparation method

[0071] In some embodiments, the preparation method of the antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive of the present invention includes: (1) Mix the polyurethane acrylate, acrylate monomer, multifunctional thiol, photoinitiator, tertiary amine, fumed silica, and additives; and (2) Vacuum defoaming.

[0072] In some implementations, step (1) mixing is performed by a dual-star dynamic mixing mixer.

[0073] In some embodiments, the mixing rate in step (1) is 600 r / min-1000 r / min, for example 600 r / min-700 r / min, 600 r / min-800 r / min, 600 r / min-900 r / min, 700 r / min-800 r / min, 700 r / min-900 r / min, 700 r / min-1000 r / min, 800 r / min-900 r / min, 800 r / min-1000 r / min, 900 r / min-1000 r / min, such as 600 r / min, 650 r / min, 700 r / min, 750 r / min, 800 r / min, 850 r / min, 900 r / min, 950 r / min, 1000 r / min, or any two of the above values ​​forming a range.

[0074] In some implementations, the mixing time for step (1) is 0.5 h to 2 h, for example 0.5 h to 1 h, 0.5 h to 1.5 h, 1 h to 1.5 h, 1 h to 2 h, 0.5 h, 1 h, 1.5 h, 2 h.

[0075] In some implementations, the vacuum degree of vacuum defoaming in step (2) is -0.09 MPa to 0.06 MPa, for example -0.09 MPa to -0.08 MPa, -0.09 MPa to -0.07 MPa, -0.08 MPa to -0.07 MPa, -0.08 MPa to -0.06 MPa, -0.07 MPa to -0.06 MPa, -0.09 MPa, -0.08 MPa, -0.07 MPa, and -0.06 MPa.

[0076] In some implementations, the product obtained by vacuum defoaming in step (2) is sealed in packaging and stored in a cool, dark place.

[0077] use

[0078] The present invention also provides the use of the polyfunctional thiols, tertiary amines and optionally fumed silica described in any embodiment herein in improving the curing rate, surface dryness, mechanical properties and / or high temperature resistance of UV-curable adhesives.

[0079] In some embodiments, the present invention also provides the use of the polyfunctional thiols, tertiary amines and optionally fumed silica described in any of the embodiments herein in the preparation of UV-curable adhesives.

[0080] In some embodiments, the other raw materials of the UV curing agent of the present invention and their amounts are as described in any embodiment herein.

[0081] The present invention has the following beneficial effects: 1. The curing agent system uses multifunctional aromatic thiols. Firstly, aromatic thiols exhibit good storage stability; secondly, the "thiol-alkene" click reaction between the thiol group and acrylate is unaffected by oxygen, significantly improving the oxygen inhibition effect. Therefore, the photo-initiated thiol-alkene click reaction and the chain-like free radical polymerization of acrylic acid can occur simultaneously, resulting in tight cross-linking of the molecular chains, thereby improving structural strength and mechanical properties, and enhancing high-temperature resistance.

[0082] 2. The tertiary amine in the curing agent system has an inhibitory effect on oxygen polymerization. As a hydrogen donor, the tertiary amine reacts with the peroxy radicals generated by oxygen to form new aminoalkyl radicals, which can re-initiate the polymerization of acrylate monomers, thereby consuming oxygen and forming a synergistic effect with thiols, further improving the oxygen polymerization inhibition of the curing agent system.

[0083] 3. Fumed silica in the curing agent system can be used as a filler to enhance mechanical strength and further improve mechanical properties at high temperatures.

[0084] In summary, this invention provides an antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive and its preparation method. This curing agent has the characteristics of rapid curing, good surface drying, excellent mechanical properties, and high-temperature resistance, and has great application prospects in 3D printing, photovoltaic new energy and other fields.

[0085] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and are not intended to limit the scope of the invention. The methods, reagents, and materials used in the embodiments and comparative examples are conventional methods, reagents, and materials in the art, unless otherwise stated. The starting material compounds in the embodiments and comparative examples are all commercially available.

[0086] Polyurethane acrylate, RU-2021B-2 material from Ruisheng New Materials.

[0087] Isoborneol acrylate, tetrahydrofurfuryl acrylate, and hydroxyethyl acrylate were all purchased from Aladdin Biochemical Technology Co., Ltd., with product numbers I418711, T102693, and H104535, respectively.

[0088] Tris-2-(3-mercaptopropoxy)ethyl isocyanurate, 1,4-benzenedimethylthiol and biphenyl-4,4'-dithiol were all purchased from Aladdin Biochemical Technology Co., Ltd., with product numbers T303548, B101791 and B152760, respectively.

[0089] 2,5-Diamino-1,4-benzenedithiol was purchased from Shanghai Haohong Biomedical Technology Co., Ltd., product number 1558844.

[0090] Benzoin dimethyl ether, purchased from Maclean Biotechnology Co., Ltd., product number B802287.

[0091] N,N-Dimethylaminobenzoate isoamyl ester was purchased from Aladdin Biochemical Technology Co., Ltd., product number I157648.

[0092] Fumed silica, purchased from Cabot Corporation, product number CAB-OSil M-5.

[0093] Silane coupling agents KH550 and KH570 were purchased from Aladdin Biochemical Technology Co., Ltd., with product numbers A107147 and S111153, respectively.

[0094] The silane coupling agent KH560 was purchased from Maclean Biotechnology Co., Ltd., product number G810441.

[0095] Polysiloxane emulsion defoamer N-10 was purchased from Foshan Nanhai Datian Chemical Co., Ltd.

[0096] Example 1

[0097] Add 60 parts by weight of polyurethane acrylate, 20 parts by weight of isobornyl acrylate, 10 parts by weight of 1,4-benzenedimethyl mercaptan, 1 part by weight of benzoin dimethyl ether, 2 parts by weight of N,N-dimethylaminobenzoate isoamyl ester, 5 parts by weight of fumed silica (particle size 7 nm-20 nm), and 2 parts by weight of additives (coupling agent KH570 and polysiloxane emulsion defoamer N-10 in a mass ratio of 3:1) into a dual planetary mixer and stir at 800 r / min for 1 h. After stirring evenly, vacuum defoaming is performed at a vacuum degree of -0.08 MPa. The mixture is then sealed in packaging and stored at low temperature and protected from light.

[0098] Example 2

[0099] 50 parts by weight of polyurethane acrylate, 25 parts by weight of isobornyl acrylate, 15 parts by weight of 2,5-diamino-1,4-benzenedithiol, 1 part by weight of benzoin dimethyl ether, 2 parts by weight of N,N-dimethylaminobenzoate isoamyl ester, 1 part by weight of triethanolamine, 5 parts by weight of fumed silica (particle size 7 nm-20 nm), and 1 part by weight of additive (coupling agent KH570 and defoamer N-10 in a mass ratio of 3:1) were added to a dual planetary mixer and stirred at 800 r / min for 1 h. After stirring evenly, the mixture was vacuum defoamed to a vacuum degree of -0.08 MPa, sealed in a package, and stored at a low temperature and protected from light.

[0100] Example 3

[0101] 50 parts by weight of polyurethane acrylate, 10 parts by weight of hydroxyethyl acrylate, 20 parts by weight of isobornyl acrylate, 10 parts by weight of biphenyl-4,4'-dithiol, 1 part by weight of benzoin dimethyl ether, 1 part by weight of 2,4-diethylthioxanthone, 2 parts by weight of N,N-dimethylaminobenzoate isoamyl ester, 5 parts by weight of fumed silica (particle size 7 nm-20 nm), and 1 part by weight of additive (coupling agent KH550 and defoamer N-10 in a mass ratio of 3:1) were added to a dual planetary mixer and stirred at 800 r / min for 1 h. After stirring evenly, the mixture was defoamed under vacuum at a vacuum degree of -0.08 MPa, sealed in packaging, and stored at low temperature and protected from light.

[0102] Example 4

[0103] 40 parts by weight of polyurethane acrylate, 10 parts of tetrahydrofurfuryl acrylate, 30 parts of isobornyl acrylate, 10 parts of biphenyl-4,4'-dithiol, 0.5 parts of benzoin dimethyl ether, 0.5 parts of benzophenone, 1 part of 2,4-diethylthioxanthrone, 2 parts of N,N-dimethylaminobenzoate isoamyl ester, 5 parts of fumed silica (particle size 7 nm-20 nm), and 1 part of additive (coupling agent KH560 and defoamer N-10 in a mass ratio of 3:1) were added to a dual planetary mixer and stirred at 800 r / min for 1 h. After stirring evenly, the mixture was defoamed under vacuum at a vacuum degree of -0.08 MPa, sealed in a package, and stored at a low temperature and protected from light.

[0104] Example 5

[0105] 50 parts by weight of polyurethane acrylate, 10 parts by weight of hydroxyethyl acrylate, 20 parts by weight of isobornyl acrylate, 15 parts by weight of biphenyl-4,4'-dithiol, 1 part by weight of benzoin dimethyl ether, 1 part by weight of 2,4-diethylthioxanthone, 2 parts by weight of N,N-dimethylaminobenzoate isoamyl ester, 5 parts by weight of fumed silica (particle size 7 nm-20 nm), and 1 part by weight of additive (coupling agent KH550 and defoamer N-10 in a mass ratio of 3:1) were added to a dual planetary mixer and stirred at 800 r / min for 1 h. After stirring evenly, the mixture was defoamed under vacuum at a vacuum degree of -0.08 MPa, sealed in packaging, and stored at low temperature and protected from light.

[0106] Comparative Example 1

[0107] Add 50 parts by weight of polyurethane acrylate, 30 parts by weight of isobornyl acrylate, 10 parts by weight of tetrahydrofurfuryl acrylate, 2 parts by weight of benzoin dimethyl ether, 1 part by weight of benzophenone, 1 part by weight of 2,4-diethylthioxanthrone, 5 parts by weight of fumed silica, and 1 part by weight of additive (coupling agent KH550 and defoamer N-10 in a mass ratio of 3:1) into a dual planetary mixer and stir at 800 r / min for 1 h. After stirring evenly, vacuum defoaming is performed with a vacuum degree of -0.08 MPa. The mixture is then sealed in packaging and stored at low temperature and protected from light.

[0108] Comparative Example 2

[0109] Add 50 parts by weight of polyurethane acrylate, 10 parts by weight of hydroxyethyl acrylate, 20 parts by weight of isobornyl acrylate, 15 parts by weight of biphenyl-4,4'-dithiol, 1 part by weight of benzoin dimethyl ether, 1 part by weight of 2,4-diethylthioxanthone, 2 parts by weight of N,N-dimethylaminobenzoate isoamyl ester, and 1 part by weight of additive (coupling agent KH550 and defoamer N-10 in a mass ratio of 3:1) into a double planetary mixer and stir at 800 r / min for 1 h. After stirring evenly, vacuum defoaming is performed at a vacuum degree of -0.08 MPa. The mixture is then sealed in packaging and stored at low temperature and protected from light.

[0110] Comparative Example 3

[0111] Without adding any multifunctional thiol components, the remaining components and preparation methods are the same as in Example 1, resulting in a cured adhesive that does not contain thiol components.

[0112] Comparative Example 4

[0113] Without adding tertiary amine components, the remaining components and preparation methods are the same as in Example 1, resulting in a cured adhesive that does not contain tertiary amines.

[0114] The weight parts of each raw material component in Examples 1-5 and Comparative Examples 1-4 are shown in Table 1.

[0115] Table 1

[0116] Test case

[0117] Photocuring conditions for the examples and comparative examples: 365 nm wavelength, light intensity 1000 mW / cm² 2 .

[0118] Examples 1-5 and Comparative Examples 1-4 were tested using the following methods.

[0119] (1) Tensile / Elongation at Break Test

[0120] Using a digital display doctor blade applicator, apply each adhesive onto the silicone release film without covering the surface. The application area is 100 mm. 100 mm 2 The film has a thickness of 300 μm and is UV-cured for 3 seconds. After curing, the UV film is cut into dumbbell-shaped (Type I) pieces conforming to the national standard GB / T528 using a utility knife. For the 115 specification rubber strip, fix the rubber strip on the tensile testing machine and stretch it along its length at a stretching speed of 100 mm / min. Record the tensile breaking strength and elongation at break. Test three strips for each sample and take the average value.

[0121] (2) Tensile / elongation at break after heating at 200℃ for 2 h

[0122] In a high-temperature universal tensile testing machine, the temperature is set to 200℃ and the heating time is 2 hours. Then, a tensile test is performed at this temperature, and the test method is as in test example (1).

[0123] (3) Oxygen inhibition performance test

[0124] Oxygen inhibition can be judged by whether the surface of the colloid is completely cured and sticky after curing. The surface curing performance is evaluated by the surface drying time method. The specific operation is as follows: First, prepare the film as in test example (1). The film size is 2. 2 cm 2 The film has a thickness of 300 μm and a UV curing time of 1 s. After curing, the film is left at room temperature for 30 min. Then, the fingertips are wiped clean with anhydrous ethanol. The finger is gently touched to the film and lifted upwards. If the sample does not stick to the finger, the surface is considered dry.

[0125] The performance of the curing agents prepared in Examples 1-5 and Comparative Examples 1-4 is summarized in Table 2.

[0126] Table 2

[0127] The data in Table 2 show that the UV-curable adhesives with polyfunctional thiols and tertiary amine systems added in Examples 1-5 all exhibited excellent surface drying properties, with no adhesion to fingers, and maintained good mechanical strength at high temperatures, with tensile strength exceeding 30 MPa.

[0128] The UV-cured adhesives of Examples 1-5 all showed a significant increase in elongation at break at high temperatures compared to their initial values. This is due to a phase transition in the adhesive itself, from a glassy state to a highly elastic state, resulting in a substantial increase in ductility. In contrast, Comparative Examples 1-3, lacking multifunctional thiols or fumed silica, not only had lower initial mechanical strength than the cured adhesives of Examples 1-5, but also experienced severe mechanical loss at high temperatures, with tensile strength decreasing and falling below 20 MPa. This is attributed to the low crosslinking density in the cured adhesive systems of Comparative Examples 1-3. Although the initial and high-temperature tensile strength, as well as the elongation at break after high temperature, of Comparative Example 4 were similar to those of Examples 1-5, the surface of the cured agent obtained was sticky, rendering the product substandard.

[0129] In the system of this invention, as in Examples 1-5, not only does the free radical polymerization of the acrylate itself occur, but also a "thiol-ene" click reaction occurs between the polyfunctional thiol and the double bond of the acrylate, thus increasing the crosslinking density. Furthermore, the fumed silica also plays a reinforcing role, resulting in a significant improvement in mechanical properties. Moreover, the "thiol-ene" click reaction is unaffected by oxygen, and the tertiary amine, as an active hydrogen donor, can quickly capture oxygen from the air. The synergistic effect of the polyfunctional thiol and the tertiary amine, as shown in Example 1 compared to Comparative Examples 3-4, demonstrates that the addition of polyfunctional thiols and tertiary amines enables the UV-curable adhesive to achieve excellent antioxidant and polymerization-inhibiting effects.

[0130] In summary, the UV curing agent of the present invention has good antioxidant and polymerization inhibition properties and high-temperature mechanical properties. It maintains its mechanical properties well after high-temperature aging, avoiding the risks of curing agent failure and debonding under high-temperature conditions. Moreover, it has good surface drying properties and has great application prospects in 3D printing, photovoltaic new energy and other fields.

Claims

1. An anti-oxidation and polymerization-resistant high-temperature resistant UV curing adhesive, characterized in that, The raw materials of the UV curing adhesive include the following raw materials in parts by weight: polyurethane acrylate 40-60 parts, acrylate monomer 20-40 parts, multifunctional mercaptan 10-30 parts, photoinitiator 1-5 parts, tertiary amine 1-5 parts, fumed silica 1-10 parts, auxiliary agent 1-3 parts.

2. The oxygen-resistant, polymerization-resistant, high-temperature-resistant UV curing adhesive according to claim 1, characterized in that: the polyurethane acrylate is an aliphatic polyurethane acrylate; and / or the polyurethane acrylate has a viscosity of 800-2000 cps / 60℃, an acid value < 5.0 mg KOH / g, a weight average molecular weight of 500-2000, and a solid content ≥ 90%.

3. The oxygen-resistant, polymerization-resistant, high-temperature-resistant UV curing adhesive according to claim 1, characterized in that: the acrylate monomer has the following structure shown in Formula I: ， wherein R1is H or C 1-6 alkyl, R2is H or C 1-10 alkyl, R3is C 1-12 alkyl, menthyl, isomenthyl, tetrahydrofurfuryl, hydroxy-substituted C 1-4 alkyl, or , the wavy line indicates the position of attachment of R3to the remainder of the compound of formula I; preferably, R1 in Formula I is H, methyl or ethyl; preferably, R2 in Formula I is H, methyl or ethyl; Preferably, R3in formula I is lauryl, isobornyl, tetrahydrofurfuryl, (CH3)2CH(CH2)5-, CH2OHCH2CH2-, CH2OHCH2-, or wherein the wavy line indicates the position at which R3is attached to the remainder of the compound of formula I; more preferably, the acrylate monomer is selected from one or more than two kinds of mixtures of cyclotrimethylolpropane formal acrylate, lauryl acrylate, isooctyl acrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, isocyanatoethyl methacrylate, isobornyl acrylate and tetrahydrofurfuryl acrylate.

4. The antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive as described in claim 1, characterized in that, said polyfunctional mercaptan is represented by R-(SH) n wherein R is selected from optionally substituted C 6-14 aryl or tris(2-propoxyethyl)isocyanurate, n is 2, 3 or 4; preferably, the multifunctional mercaptan is selected from one or more than two kinds of mixtures of tri-2-(3-mercaptopropoxy)ethyl isocyanurate, 1,4-benzenedimethanethiol, diphenyl-4,4'-dithiol and 2,5-diamino-1,4-benzenedimethanethiol; more preferably, the multifunctional mercaptan is selected from one or more than two kinds of mixtures of 1,4-benzenedimethanethiol, diphenyl-4,4'-dithiol and 2,5-diamino-1,4-benzenedimethanethiol.

5. The antioxidant, polymerization-inhibiting, high-temperature UV-curable adhesive as described in claim 1, characterized in that, the photoinitiator is one or more than two kinds of mixtures of benzoin dimethyl ether, 2-hydroxymethylphenylpropanone, 1-hydroxycyclohexyl phenyl ketone, benzophenone and thioxanthone; preferably, the thioxanthone is selected from one or more than two kinds of mixtures of 2,4-diethyl thioxanthone and 2-isopropyl thioxanthone.

6. The antioxidant-polymerization resistant high temperature resistant UV curable adhesive according to claim 1, wherein, the tertiary amine has the following structure shown in Formula II: ， wherein R4, R5and R6are each independently C 1-6 alkyl, hydroxy-substituted C 1-6 alkyl, phenyl or C 1-6 alkoxy-substituted phenyl; preferably, the tertiary amine is selected from one or more than two kinds of mixtures of triethylamine, triethanolamine, N,N-dimethyl aniline and N,N-dimethylamino isopentyl benzoate in any proportion.

7. The oxygen-inhibited, high temperature resistant, UV curable adhesive of claim 1, wherein, the fumed silica has a particle size of 7 nm-20 nm.

8. The antioxidant-polymerization resistant high temperature resistant UV curable adhesive according to claim 1, wherein, the auxiliary agent comprises a coupling agent and a defoaming agent; preferably, the mass ratio of the coupling agent and the defoaming agent is (1-5):1, preferably (2-4):1; preferably, the coupling agent is selected from any one of silane coupling agents KH550, KH560 and KH570; preferably, the defoaming agent is polysiloxane emulsion defoaming agent N-10.

9. The oxygen-inhibited, high temperature resistant, UV curable adhesive of claim 1, wherein, The raw materials of the UV curing agent include: (1) polyurethane acrylate, which is 40-60 parts by weight of aliphatic polyurethane acrylate, which can have a viscosity of 800-2000 cps / 60℃, an acid value < 5.0 mg KOH / g, a functionality of 2-6, a weight average molecular weight of 500-2000, and a solid content ≥ 90%; (2) acrylic ester monomer, which is isobornyl acrylate, hydroxyethyl acrylate and / or tetrahydrofurfuryl acrylate, the total amount of which is 20-40 parts by weight; (3) polyfunctional mercaptan, which is 1,4-benzenedimethanethiol, 2,5-diamino-1,4-benzenedithiol and / or diphenyl-4,4'-dithiol, the total amount of which is 10-15 parts by weight; (4) photoinitiator, which is benzoin dimethyl ether, 2,4-diethylthioxanthone and / or benzophenone, the total amount of which is 1-2 parts by weight; (5) tertiary amine, which is isopentyl N,N-dimethylaminobenzoate and / or triethanolamine, the total amount of which is 1-3 parts by weight; (6) fumed silica, 3-7 parts by weight; (7) auxiliary agent, which is coupling agent KH550, KH560 and / or KH570, and polysiloxane emulsion defoaming agent N-10, the total amount of which is 1-2 parts by weight, the mass ratio of coupling agent to defoaming agent being (2-4):

1.

10. The method of claim 1-9, wherein the method is characterized by, The method comprises the following steps: (1) uniformly mixing the polyurethane acrylate, acrylic ester monomer, polyfunctional mercaptan, photoinitiator, tertiary amine, fumed silica and auxiliary agent; and (2) vacuum defoaming; Preferably, the step (1) of uniform mixing is completed by a double-star action dynamic mixing stirrer; More preferably, the stirring rate of the step (1) of uniform mixing is 600 r / min-1000 r / min, and the stirring time is 0.5 h-2 h; Preferably, the vacuum degree of the step (2) of vacuum defoaming is -0.09 MPa to -0.06 MPa; Preferably, the product obtained by the step (2) of vacuum defoaming is sealed and packaged, and stored in low temperature and away from light.

11. Applications selected from the following: (1) application of polyfunctional mercaptan, tertiary amine and optional fumed silica in improving the curing rate, surface dryness, mechanical properties and / or high temperature resistance of UV curing adhesive; (2) application of polyfunctional mercaptan, tertiary amine and optional fumed silica in preparing UV curing adhesive; wherein, The polyfunctional mercaptan is as claimed in claim 4, and the tertiary amine is as claimed in claim 6.

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