Ultraviolet-heat dual-curing adhesive with low thermal expansion coefficient, long storage period and high reworkability and application of ultraviolet-heat dual-curing adhesive

Abstract

The invention relates to an ultraviolet-heat dual-curing adhesive with low thermal expansion coefficient, long storage period and high reworkability and application thereof, and belongs to the technical field of adhesives. The adhesive comprises the following components in parts by weight: 5-30 parts of epoxy resin, 5-30 parts of a reactive diluent, 1-10 parts of an acrylate block copolymer with amino groups, 50-80 parts of a filler, 0.5-3 parts of a cationic photoinitiator, 0.5-3 parts of a cationic thermal initiator, 0.05-3 parts of a photosensitizer and 0.1-3 parts of a thixotropic agent, the amino group content of the copolymer is 0.5-6.0 mmol / g, and the weight-average molecular weight of the copolymer is 50,000-150,000 g / mol. By adding the copolymer, the stability of the adhesive can be improved, and the storage period can be prolonged; and during repair heating, the adhesive can be softened and stripped on the premise of not damaging the precise base material, so that the repair performance of the adhesive is remarkably improved, and the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability, and its application. Background Technology

[0002] When two bonded substrates (such as a chip and a substrate) have significantly different coefficients of thermal expansion (CTE), temperature changes can generate shear stress at the interface. This can lead to problems such as cracking of the adhesive layer itself, cracking of delicate and brittle substrates (such as silicon chips, glass, and ceramics), delamination (separation) of the interface, and performance drift or failure of devices (such as optical focus deviation or frequency drift). Therefore, in applications involving precision components, multiple material combinations, drastic temperature changes, and high reliability requirements, such as optical communications and automotive electronics, adhesives are required to have a low coefficient of thermal expansion (CTE). To reduce the CTE of their cured products, adhesives typically add inorganic filler particles with low CTE, such as unmodified silica, to the matrix.

[0003] Adding unmodified silica to cationic adhesives leads to poorer adhesive stability and shorter service life. This is because silica contains silanol groups (-Si-OH) on its surface. These groups are weakly acidic (pKa≈4-7) and can destroy the stability of cationic initiators through proton transfer reactions. Furthermore, the higher the amount of silica added, the worse the stability of the adhesive.

[0004] To ensure the stability of cationic adhesives, amine compounds are added. This is because the amino groups in amine compounds react chemically with the silanol groups (-Si-OH) on the surface of silica, thus maintaining the stability of the cationic adhesive. However, because this reaction is slow, the effect is often unsatisfactory.

[0005] On the other hand, to reduce production costs, many companies want adhesives to have reworkability, enabling them to disassemble valuable components using heating methods without damaging the substrate. However, silica also affects the reworkability of adhesives, and the higher the silica content, the worse the reworkability. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a UV-thermal dual-curing adhesive with a low coefficient of thermal expansion (CTE), long shelf life, and high reworkability, as well as its applications. This adhesive exhibits a low CTE, effectively preventing problems such as cracking of the adhesive layer itself, cracking of delicate brittle substrates, debonding of the bonding interface, and performance drift or failure of devices when the coefficients of thermal expansion differ significantly between the bonded substrates and the ambient temperature varies considerably. Furthermore, even with a high silica content, this adhesive still enhances the stability of cationic adhesive systems, extends shelf life, and possesses excellent reworkability, significantly reducing production costs.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability, characterized in that it comprises, by weight, 5-30 parts epoxy resin, 5-30 parts reactive diluent, 1-10 parts amino-containing acrylate block copolymer, 50-80 parts filler, 0.5-3 parts cationic photoinitiator, 0.5-3 parts cationic thermal initiator, 0.05-3 parts photosensitizer, and 0.1-3 parts thixotropic agent, wherein the amino content of the amino-containing acrylate block copolymer is 0.5-6.0 mmol / g, and the weight-average molecular weight of the amino-containing acrylate block copolymer is 50,000-150,000 g / mol.

[0009] The adhesive provided by this invention can be cured by both ultraviolet light and heat. After dispensing, it can be cured quickly by irradiating with ultraviolet light for 5 seconds, which plays a positioning role and prevents displacement between the lens and the substrate. Then, it is heated for deep curing to prevent the adhesive that cannot be irradiated by ultraviolet light from migrating to the lens surface and affecting the image quality.

[0010] In this invention, the epoxy resin is in the form of 5-30 parts by weight, for example, 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts or 30 parts, etc.

[0011] In this invention, the active diluent is in the form of 5-30 parts by weight, for example, 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts or 30 parts, etc.

[0012] In this invention, the final strength and adhesion of the adhesive layer are mainly provided by the thermosetting crosslinking network formed after the epoxy resin is thermocured; the initial strength and adhesion of the adhesive layer are mainly provided by the UV-cured crosslinking network formed after the reactive diluent is UV-cured. Simultaneously, the reactive diluent reduces the viscosity of the adhesive system, facilitating dispensing. Compared to epoxy resin, if the reactive diluent content is too low, the initial strength of the adhesive layer may be insufficient, and the lens and substrate may still easily shift; if the reactive diluent content is too high, it is easy for the reactive diluent to diffuse on the substrate, penetrate and migrate to the crystal surface, affecting the light transmission performance of the lens.

[0013] In this invention, the amino-containing acrylate block copolymer is 1-10 parts by weight, for example, it can be 1.0 part, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, 5.0 parts, 5.5 parts, 6.0 parts, 6.5 parts, 7.0 parts, 7.5 parts, 8.0 parts, 8.5 parts, 9.0 parts, 9.5 parts, or 10 parts, etc.

[0014] In this invention, the filler is 50-80 parts by weight, for example, 50 parts, 52 parts, 55 parts, 58 parts, 60 parts, 62 parts, 65 parts, 68 parts, 70 parts, 72 parts, 75 parts, 78 parts or 80 parts, etc.

[0015] The adhesive provided by this invention incorporates an amino-containing acrylate block copolymer and a filler. The filler's primary function is to reduce the coefficient of thermal expansion (CTE) of the cationic adhesive system, while the amino-containing acrylate block copolymer's primary function is to inhibit the filler's detrimental effect on the stability of the cationic adhesive system and improve its reworkability. Through their synergistic effect, both the CTE of the cationic adhesive system and its stability and reworkability are effectively reduced. Adding only a filler would only reduce the CTE of the cationic adhesive system, potentially worsening its stability and reworkability; adding only an amino-containing acrylate block copolymer would not achieve the goal of reducing the CTE of the cationic adhesive system.

[0016] In this invention, the cationic photoinitiator is 0.5-3 parts by weight, for example, 0.5 parts, 0.8 parts, 1.0 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.5 parts, 2.8 parts, or 3.0 parts, etc.

[0017] In this invention, the cationic thermal initiator is 0.5-3 parts by weight, for example, 0.5 parts, 0.8 parts, 1.0 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.5 parts, 2.8 parts, or 3.0 parts, etc.

[0018] In this invention, the photosensitizer is present in weight parts of 0.05-3 parts, for example, 0.05 parts, 0.08 parts, 0.10 parts, 0.20 parts, 0.50 parts, 0.80 parts, 1.0 part, 1.2 parts, 1.5 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.5 parts, 2.8 parts, or 3.0 parts, etc.

[0019] In this invention, the thixotropic agent is 0.1-3 parts by weight, for example, it can be 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1.0 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.5 parts, 2.8 parts or 3.0 parts, etc.

[0020] In this invention, the amino content of the amino-containing acrylate block copolymer is 0.5-6.0 mmol / g, for example, it can be 0.5 mmol / g, 0.8 mmol / g, 1.0 mmol / g, 1.2 mmol / g, 1.5 mmol / g, 1.8 mmol / g, 2.0 mmol / g, 2.2 mmol / g, 2.5 mmol / g, 2.8 mmol / g, 3.0 mmol / g, 3.2 mmol / g, 3.5 mmol / g, 3.8 mmol / g, 4.0 mmol / g, 4.2 mmol / g, 4.5 mmol / g, 4.8 mmol / g, 5.0 mmol / g, 5.2 mmol / g, 5.5 mmol / g, 5.8 mmol / g, or 6.0 mmol / g, etc.

[0021] In this invention, the weight-average molecular weight of the amino-containing acrylate block copolymer is 50,000-150,000 g / mol, for example, it can be 50,000 g / mol, 55,000 g / mol, 60,000 g / mol, 65,000 g / mol, 70,000 g / mol, 75,000 g / mol, 80,000 g / mol, 85,000 g / mol, 90,000 g / mol, 95,000 g / mol, 100,000 g / mol, 105,000 g / mol, 110,000 g / mol, 115,000 g / mol, 120,000 g / mol, 125,000 g / mol, 130,000 g / mol, 135,000 g / mol, 140,000 g / mol, 145,000 g / mol, or 150,000 g / mol, etc.

[0022] In this invention, the amino content and weight-average molecular weight of the amino-containing acrylate block copolymer are within the aforementioned range, ensuring that the cationic adhesive system has a low coefficient of thermal expansion (CTE) and excellent stability and reworkability. If the amino content and weight-average molecular weight of the amino-containing acrylate block copolymer are too high or too low, the synergistic effect of the two will be affected. If the amino content of the copolymer is too high, steric hindrance and the formation of pre-crosslinked gel particles will occur, hindering the reaction between amino and silanol groups, thus worsening the stability of the cationic adhesive system. In addition, it will also lead to excessive pre-crosslinking between copolymer chains, forming a rigid and dense network, making the cohesive structure of the colloid brittle, increasing the DSC initiation temperature, and worsening the reworkability of the cationic adhesive system. If the amino content of the copolymer is too low, the insufficient amino groups cannot bind with the silanol groups on the silica surface, thus affecting the coating formation of the copolymer on the silica surface and failing to suppress the destructive effect of the silanol groups on the stability of the cationic initiator. Furthermore, because there are not enough amino groups on the copolymer to form strong Si-N covalent bonds with the silanol groups on the silica filler surface, the anchoring points between them are sparse and weak. During rework heating, the adhesive bulk softens, the cohesive strength decreases, and the rework performance deteriorates. If the weight-average molecular weight of the copolymer is too high, the copolymer chains are too long, and the entanglement density is extremely high, making chain movement difficult and dispersion in the adhesive challenging. This leads to a higher DSC initiation temperature and worsens the rework performance of the cationic adhesive system. Simultaneously, the excessively long copolymer chains and severe chain entanglement result in extremely slow chain segment movement and extremely high overall viscosity. The terminal amino groups are "frozen" in a huge entangled network, making it very difficult for them to diffuse to the silica surface. The reaction rate is limited by slow chain segment movement, making it impossible for them to effectively contact and react with the silanol groups on the silica surface, thus deteriorating the stability of the cationic adhesive system. If the weight-average molecular weight of the copolymer is too low, the copolymer chains are too short, and the chain entanglement is severely insufficient, an effective strength network cannot be formed, resulting in insufficient cohesive strength in the adhesive and thus deteriorating the reworkability of the cationic adhesive system. Due to the short copolymer chains, although the overall movement is fast, its conformational fluctuations are small. Although the terminal amino groups move quickly, they lack the "direction" and "driving force" provided by the conformational changes of long chains pointing towards the silanol groups on the silica surface. Moreover, short chains are more likely to form random coils, and their ends are more likely to be wrapped in the coils, making it difficult for the amino groups to be exposed and contact the silanol groups on the silica surface, thus deteriorating the stability of the cationic adhesive system.

[0023] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0024] As a preferred embodiment of the present invention, the adhesive comprises the following components in parts by weight:

[0025] The composition comprises 5-30 parts epoxy resin, 5-30 parts reactive diluent, 2-8 parts amino-containing acrylate block copolymer, 50-80 parts filler, 0.5-3 parts cationic photoinitiator, 0.5-3 parts cationic thermal initiator, 0.05-3 parts photosensitizer, and 0.1-3 parts thixotropic agent. The amino content of the amino-containing acrylate block copolymer is 2.0-4.0 mmol / g, and the weight-average molecular weight of the amino-containing acrylate block copolymer is 80,000-120,000 g / mol.

[0026] Preferably, the adhesive comprises the following components in parts by weight:

[0027] The composition includes 20 parts epoxy resin, 15 parts reactive diluent, 5 parts amino-containing acrylate block copolymer, 65 parts filler, 1.5 parts cationic photoinitiator, 2 parts cationic thermal initiator, 1.5 parts photosensitizer, and 1.5 parts thixotropic agent. The amino content of the amino-containing acrylate block copolymer is 3.0 mmol / g, and the weight-average molecular weight of the amino-containing acrylate block copolymer is 100,000 g / mol.

[0028] Preferably, the weight ratio of the amino-containing acrylate block copolymer to the filler is 1:(10-15); more preferably, the weight ratio of the amino-containing acrylate block copolymer to the filler is 1:12.

[0029] Preferably, the amino-containing acrylate block copolymer is selected from any one or a combination of two of amino-containing methyl methacrylate-acrylate-methyl methacrylate block copolymers or amino-containing ethylene-butyl acrylate copolymers.

[0030] Preferably, the amino-containing methyl methacrylate-acrylate-methyl methacrylate block copolymer is selected from any one or a combination of at least two of the following: amino-containing methyl methacrylate-methyl acrylate-methyl methacrylate block copolymer, amino-containing methyl methacrylate-ethyl acrylate-methyl methacrylate block copolymer, amino-containing methyl methacrylate-propyl acrylate-methyl methacrylate block copolymer, and amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer.

[0031] Preferably, the filler is silica. The shape of the silica is not particularly limited; for example, spherical, granular, or flake silica can be used. The average particle size of the silica is preferably 0.1 μm-50 μm, more preferably 0.1 μm-30 μm, even more preferably 0.1 μm-20 μm, and most preferably 2-10 μm.

[0032] Preferably, the epoxy resin is any one or a combination of at least two of the following: alicyclic epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin, or glycidyl ester epoxy resin.

[0033] Preferably, the reactive diluent is any one or a combination of at least two of the following: 3-ethyl-3-oxabutane methanol, 4-ethyl-3-[(benzyloxy)methyl]oxetane, 3,3'-(oxybis(methylene)bis(3-ethyl)oxetane, ethyl-3-((epoxyethylmethoxy)methyl)oxetane, 3-ethyl-3-[(ethylene oxide-2-methoxy)methyl]oxetane, 3,3-[1,4-butylbis(oxymethyl)]bis[3-ethyloxetane, 1,4-bis[(3-ethyl-3-oxetane-butylmethoxy)methyl]benzene, and 4,4'-hydroxymethylbiphenyl copolymer oxetane.

[0034] Preferably, the cationic photoinitiator is any one or a combination of at least two of the following: triarylhexafluorophosphate thioonium salt, triarylhexafluoroantimonate thioonium salt, diarylhexafluorophosphate iodium salt, and diarylhexafluoroantimonate iodium salt.

[0035] Preferably, the cationic thermal initiator is any one or a combination of at least two of Vicbase TC3630, Vicbase TC3632, Vicbase TC3633 and Vicbase TC3634.

[0036] Preferably, the photosensitizer is any one or a combination of at least two of 1-hydroxy-cyclohexyl-phenyl ketone, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, isopropylthioxanthone, 9,10-diethoxyanthracene, 9,10-dibutoxyanthracene and N-vinylcarbazole.

[0037] Preferably, the thixotropic agent is any one or a combination of at least two of fumed silica, precipitated silica and organobentonite.

[0038] Secondly, the present invention provides an application of the first aspect adhesive, which is used for bonding and encapsulating optical components and microelectronic devices in the optical communication industry or for power module encapsulation in the automotive electronics and new energy industries.

[0039] The UV-thermal dual-curing adhesive provided by this invention has a low coefficient of thermal expansion, long shelf life, and high reworkability. It can be used to bond a variety of substrates with different coefficients of thermal expansion, such as optical lenses and substrates, chips and substrates.

[0040] The UV-thermal dual-curing adhesive provided by this invention, characterized by a low coefficient of thermal expansion, long shelf life, and high reworkability, can be used for bonding optical lenses to substrates, such as mobile phone prism lenses, and substrates such as metals, polymers (e.g., PC), and ceramics; it can also be used for bonding chips to substrates, such as chips, glass, and ceramics.

[0041] This invention does not impose any special limitations on the curing method of the adhesive. For example, the following method can be used: after dispensing the adhesive, use 800-1200 mW / cm... 2 Irradiate with ultraviolet light for 4-8 seconds, then heat at 90℃ for 40 minutes to cure.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] (1) In the prior art, amine compounds are added to suppress the damage of silica to cationic initiators. The amino groups in the amine compounds react chemically with the silanol groups (-Si-OH) on the surface of silica to form a coating, thereby improving the stability of the adhesive and extending its service life. However, the above chemical reaction is relatively slow and the effect is not good, mainly due to the steric hindrance effect. In this invention, an amino-containing acrylate block copolymer is added to the adhesive, with an amino content of 0.5-6.0 mmol / g and a weight-average molecular weight of 50,000-150,000 g / mol. At this time, the adhesive has a sufficiently high number of amino groups to ensure the collision probability, avoids unfavorable pre-crosslinking and steric hindrance, and has sufficiently fast chain segment mobility to quickly transport the amino groups to the vicinity of the silanol groups on the silica surface, thereby greatly increasing the probability of effective condensation reaction with the silanol groups, improving the stability of the cationic adhesive system, and extending its service life.

[0044] (2) Because there are enough amino groups to form a strong and uniform covalent bond network with the silanol groups on the silica surface, and the copolymer chains are long enough to form a sufficient and moderate chain entanglement network, the cohesive strength of the adhesive is very high at room temperature. When rework heating is applied, the adhesive body (especially the physical crosslinking points) softens, and the interfacial bonding strength is also significantly reduced and is less than the cohesive strength of the adhesive. When external force is applied, the stress cannot destroy the adhesive body or be guided to the interface between the adhesive and the substrate, so that the adhesive can be softened and peeled off without damaging the precision substrate, which significantly improves the rework performance of the adhesive and greatly reduces production costs. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and comparative examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0046] To fully and clearly explain the implementation process, some raw material parameters and sources are disclosed as follows:

[0047] Epoxy resin: 2021P, provided by Daicel Investment Co., Ltd.

[0048] Reactive diluent: 3-ethyl-3-oxabutane methanol, provided by Changzhou Qiangli Electronic New Materials Co., Ltd.

[0049] Amino-containing acrylate block copolymers:

[0050] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A1: amino content is 0.5 mmol / g, weight average molecular weight is 50000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0051] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A2: amino content is 3.5 mmol / g, weight average molecular weight is 100,000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0052] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A3: amino content is 6.0 mmol / g, weight average molecular weight is 150000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0053] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A4: amino content is 0.10 mmol / g, weight average molecular weight is 50000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0054] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A5: amino content is 0.30 mmol / g, weight average molecular weight is 100,000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0055] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A6: amino content is 0.45 mmol / g, weight average molecular weight is 150000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0056] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A7: amino content is 6.1 mmol / g, weight average molecular weight is 50000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0057] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A8: amino content is 6.2 mmol / g, weight average molecular weight is 100,000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0058] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A9: amino content is 6.5 mmol / g, weight average molecular weight is 150,000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0059] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A10: amino content is 0.5 mmol / g, weight average molecular weight is 40000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0060] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A11: amino content is 3.5 mmol / g, weight average molecular weight is 45000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0061] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A12: amino content is 6.0 mmol / g, weight average molecular weight is 48000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0062] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A13: amino content is 0.5 mmol / g, weight average molecular weight is 152000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0063] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A14: amino content is 3.5 mmol / g, weight average molecular weight is 158000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0064] Amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A15: amino content is 6.0 mmol / g, weight average molecular weight is 165000 g / mol, provided by Shanghai Rensu New Materials Co., Ltd.

[0065] Silica: BQ020-1, provided by Suzhou Jinyi New Material Technology Co., Ltd.;

[0066] Cationic photoinitiator: triarylhexafluorophosphate thioonium salt, provided by Changzhou Qiangli Electronic New Materials Co., Ltd.;

[0067] Cationic thermal initiator: Vicbase TC3632, provided by Shenzhen Kaiji Applied Materials Co., Ltd.;

[0068] Photosensitizer: Hydroxycyclohexylphenyl ketone, provided by Double Bond Chemical (Shanghai) Co., Ltd.;

[0069] Thixotropic agent: Aerosil R202, supplied by Evonik Degussa Ltd.

[0070] Example 1

[0071] This embodiment provides a UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability, comprising the following components in parts by weight:

[0072] 20 parts epoxy resin, 15 parts reactive diluent, 1 part amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A1, 65 parts silica, 1.5 parts cationic photoinitiator, 2 parts cationic thermal initiator, 1.5 parts photosensitizer and 1.5 parts thixotropic agent.

[0073] The preparation method of a UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is as follows:

[0074] S1: Weigh 20kg of epoxy resin and 15kg of reactive diluent and put them into the mixing tank for stirring. Set the stirring speed to 90rpm and stir for 10 minutes.

[0075] S2: Continue adding 1 kg of amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A1, 65 kg of silica, 1.5 kg of cationic photoinitiator, and 2 kg of cationic thermal initiator to the mixing tank and stir at 100 rpm for 20 minutes.

[0076] S3: Continue to add 1.5 kg of photosensitizer and 1.5 kg of thixotropic agent to the mixing tank and stir. Set the stirring speed to 20 rpm and the stirring time to 25 minutes. Finally, filter and package the mixture to obtain the UV-thermal dual-curing adhesive with low thermal expansion coefficient, long shelf life and high reworkability.

[0077] Example 2

[0078] This embodiment provides a UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability, comprising the following components in parts by weight:

[0079] 20 parts epoxy resin, 15 parts reactive diluent, 5 parts amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A2, 65 parts silica, 1.5 parts cationic photoinitiator, 2 parts cationic thermal initiator, 1.5 parts photosensitizer and 1.5 parts thixotropic agent.

[0080] The preparation method of a UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is as follows:

[0081] S1: Weigh 20kg of epoxy resin and 15kg of reactive diluent and put them into the mixing tank for stirring. Set the stirring speed to 90rpm and stir for 10 minutes.

[0082] S2: Continue adding 5 kg of amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A2, 65 kg of silica, 1.5 kg of cationic photoinitiator, and 2 kg of cationic thermal initiator to the mixing tank and stir at 100 rpm for 20 minutes.

[0083] S3: Continue to add 1.5 kg of photosensitizer and 1.5 kg of thixotropic agent to the mixing tank and stir. Set the stirring speed to 20 rpm and the stirring time to 25 minutes. Finally, filter and package the mixture to obtain the UV-thermal dual-curing adhesive with low thermal expansion coefficient, long shelf life and high reworkability.

[0084] Example 3

[0085] This embodiment provides a UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability, comprising the following components in parts by weight:

[0086] 20 parts epoxy resin, 15 parts reactive diluent, 10 parts amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A3, 65 parts silica, 1.5 parts cationic photoinitiator, 2 parts cationic thermal initiator, 1.5 parts photosensitizer and 1.5 parts thixotropic agent.

[0087] The preparation method of a UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is as follows:

[0088] S1: Weigh 20kg of epoxy resin and 15kg of reactive diluent and put them into the mixing tank for stirring. Set the stirring speed to 90rpm and stir for 10 minutes.

[0089] S2: Continue to add 10 kg of amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A3, 65 kg of silica, 1.5 kg of cationic photoinitiator and 2 kg of cationic thermal initiator to the mixing tank and stir. The stirring speed is set to 100 rpm and the stirring time is 20 minutes.

[0090] S3: Continue to add 1.5 kg of photosensitizer and 1.5 kg of thixotropic agent to the mixing tank and stir. Set the stirring speed to 20 rpm and the stirring time to 25 minutes. Finally, filter and package the mixture to obtain the UV-thermal dual-curing adhesive with low thermal expansion coefficient, long shelf life and high reworkability.

[0091] Comparative Example 1

[0092] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference from Example 1 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A4, while the other components, dosages, and preparation steps are the same as in Example 1.

[0093] Comparative Example 2

[0094] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference between this adhesive and Example 2 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A5. The other components, dosages, and preparation steps are the same as in Example 2.

[0095] Comparative Example 3

[0096] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference between this adhesive and Example 3 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A6. The other components, dosages, and preparation steps are the same as in Example 3.

[0097] Comparative Example 4

[0098] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference from Example 1 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A7, while the other components, dosages, and preparation steps are the same as in Example 1.

[0099] Comparative Example 5

[0100] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference between this adhesive and Example 2 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A8. The other components, dosages, and preparation steps are the same as in Example 2.

[0101] Comparative Example 6

[0102] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference between this adhesive and Example 3 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A9. The other components, dosages, and preparation steps are the same as in Example 3.

[0103] Comparative Example 7

[0104] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference from Example 1 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A10, while the other components, dosages, and preparation steps are the same as in Example 1.

[0105] Comparative Example 8

[0106] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference between this adhesive and Example 2 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A11. The other components, dosages, and preparation steps are the same as in Example 2.

[0107] Comparative Example 9

[0108] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference between this adhesive and Example 3 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A12. The other components, dosages, and preparation steps are the same as in Example 3.

[0109] Comparative Example 10

[0110] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference from Example 1 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A13, while the other components, dosages, and preparation steps are the same as in Example 1.

[0111] Comparative Example 11

[0112] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference between this adhesive and Example 2 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A14. The other components, dosages, and preparation steps are the same as in Example 2.

[0113] Comparative Example 12

[0114] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference between this adhesive and Example 3 is that the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer is A15. The other components, dosages, and preparation steps are the same as in Example 3.

[0115] Comparative Example 13

[0116] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference between this adhesive and Examples 1-3 is that the amount of amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer added is 0 parts, while the other components, dosages, and preparation steps are the same as in Examples 1-3.

[0117] Comparative Example 14

[0118] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference from Example 2 is that the amount of amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A2 added is 0.5 parts, while the other components, dosages, and preparation steps are the same as in Example 2.

[0119] Comparative Example 15

[0120] A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability is provided. The difference from Example 3 is that the amount of amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A3 added is 11 parts, while the other components, dosages, and preparation steps are the same as in Example 3.

[0121] The adhesive samples of Examples 1-3 and Comparative Examples 1-15 prepared by the above method were tested according to the following methods:

[0122] Test 1: Determination of Adhesive Strength

[0123] A1: Take two chips and determine the bonding area and size as 5mm×10mm;

[0124] A2: Take a small amount of adhesive, apply it and cover the bonding area, and then make the bonding area completely adhered;

[0125] A3: Allow to cure fully according to the adhesive curing conditions;

[0126] A4: After curing, allow the bonded workpieces to cool fully to room temperature before loading them into a tensile testing machine (model SY-500, manufactured by Dongguan Jinton Testing Equipment Co., Ltd.).

[0127] A5: Set the speed of the tensile testing machine to "10mm / min", move the tensile testing machine upward until the two chips are pulled apart, and record the maximum tensile force value during this process;

[0128] A6: Calculate the shear strength of the adhesive based on the average tensile force.

[0129] Note: Shear strength (MPa) = Average tensile force (N) / Bonded area (mm²) 2 )

[0130] Test 2: DSC Measurement

[0131] B1: Turn on the power to the DSC (Differential Scanning Calorimeter, model DSC25, manufactured by Waters Instruments, Inc., USA), connect the protective gas nitrogen, and adjust the pressure to 10-20 PSI;

[0132] B2: Start the control computer, run the Trios software, and click the "Connect" button to establish communication with the instrument;

[0133] B3: Weigh 5-10 mg of adhesive sample, place it in an aluminum crucible and seal it;

[0134] B4: Set the temperature range to 25℃-250℃ and the heating rate to 10℃ / min;

[0135] B5: Click the "Start" button to begin the experiment;

[0136] B6: After the experiment, switch the page to the "Results" interface and analyze the DSC curve.

[0137] Test 3: Viscosity Measurement

[0138] C1: Open the cone-plate viscometer (model DVNext, manufactured by BROOKFIELD) and install the 51# rotor;

[0139] C2: Press the "Rotor" key and enter the corresponding rotor number "51";

[0140] C3: Switch the page to the "Parameter Setting" interface and set the speed to 5 rpm;

[0141] C4: Place 0.5 mL of adhesive sample in the center of the sample cup and close it up to fix it;

[0142] C5: When the temperature of the cone-plate viscometer rises to 25±0.3℃, press the "Measure" button to enter the test state;

[0143] C6: Read the data from the cone-plate viscometer within 1 minute as the viscosity measurement result of the adhesive.

[0144] Test 4: Determination of Reworkability

[0145] D1: Place the bonded and cured chip in an oven at 200℃ and bake it.

[0146] D2: Remove after 10 minutes and peel off the adhesive strip with a scraper;

[0147] D3: Rating is performed according to the method in Table 1 based on the amount of adhesive residue on the chip.

[0148] Table 1

[0149] level The percentage (A%) of the residual adhesive strip area relative to the total adhesive spread area. Repairability Level 1 A%=0% excellent Level 2 A%≤5% good Level 3 5%＜A%≤15% Pass Level 4 15%＜A%≤35% Poor Level 5 A%＞35% Difference

[0150] The results of the above performance tests are shown in Table 2 below:

[0151] Table 2

[0152] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Comparative Example 14 Comparative Example 15 Adhesion strength (MPa) 17.2 19.5 18.8 16.8 18.5 17.7 17.1 17.9 18.0 16.9 18.8 17.5 16.4 18.3 17.2 16.3 16.7 19.1 DSC initial reaction temperature (°C) 91 91 91 91 91 91 92 92 92 91 91 91 92 92 92 91 91 92 Viscosity increase rate (%) at room temperature over 24 hours ＜1 ＜1 ＜1 85 72 81 69 87 74 80 71 89 83 67 84 82 35 ＜1 Repair Performance Level Level 1 Level 1 Level 1 Level 5 Level 5 Level 5 Level 5 Level 5 Level 5 Level 5 Level 5 Level 5 Level 5 Level 5 Level 5 Level 5 Level 3 Level 1

[0153] As can be seen from the test results in Table 2, the adhesives of Examples 1-3 containing amino-containing acrylate block copolymers of the present invention have significantly better viscosity stability and repair performance, and the DSC initiation reaction temperature remains almost unchanged; at the same time, the bonding strength of the prepared adhesives is also improved to a certain extent.

[0154] Compared with Examples 1-3, Comparative Examples 1-3 had poorer viscosity stability and reworkability, and a certain decrease in adhesive strength, because the amino content in the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A4-A6 was <0.5 mmol / g.

[0155] Compared with Examples 1-3, Comparative Examples 4-6 had poorer viscosity stability and reworkability, and a certain decrease in bond strength, and a slightly higher DSC initiation temperature because the amino content in the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A7-A9 was >6.0 mmol / g.

[0156] Compared with Examples 1-3, Comparative Examples 7-9 had poor viscosity stability and reworkability, and the bonding strength was also reduced to some extent because the added amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A10-A12 had a weight average molecular weight of <50000 g / mol.

[0157] Compared with Examples 1-3, Comparative Examples 10-12 had poor viscosity stability and reworkability of the adhesive due to the addition of amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A13-A15 with a weight average molecular weight >150000 g / mol, and the adhesive strength also decreased to a certain extent. The DSC initiation reaction temperature was slightly increased.

[0158] Compared with Examples 1-3, Comparative Example 13, due to the absence of amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymers A1, A2, or A3, resulted in poorer viscosity stability and reworkability of the adhesive, as well as a certain decrease in bond strength.

[0159] Compared with Example 2, Comparative Example 14 had slightly worse viscosity stability and reworkability, and the bonding strength was also reduced to some extent because the amount of amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A2 added was insufficient.

[0160] Compared with Example 3, Comparative Example 15 showed a slight increase in adhesive strength due to the addition of too much amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer A3, which led to an increase in the DSC initiation temperature of the adhesive.

[0161] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0162] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A UV-thermal dual-curing adhesive with low coefficient of thermal expansion, long shelf life, and high reworkability, characterized in that, The product comprises, by weight, 5-30 parts epoxy resin, 5-30 parts reactive diluent, 1-10 parts amino-containing acrylate block copolymer, 50-80 parts filler, 0.5-3 parts cationic photoinitiator, 0.5-3 parts cationic thermal initiator, 0.05-3 parts photosensitizer, and 0.1-3 parts thixotropic agent; wherein the amino content of the amino-containing acrylate block copolymer is 0.5-6.0 mmol / g, and the weight-average molecular weight of the amino-containing acrylate block copolymer is 50,000-150,000 g / mol.

2. The adhesive according to claim 1, characterized in that, The weight ratio of the amino-containing acrylate block copolymer to the filler is 1:(10-15). Preferably, the amino-containing acrylate block copolymer is selected from any one or a combination of two of amino-containing methyl methacrylate-acrylate-methyl methacrylate block copolymers or amino-containing ethylene-butyl acrylate copolymers. Preferably, the amino-containing methyl methacrylate-acrylate-methyl methacrylate block copolymer is selected from any one or a combination of at least two of the following: amino-containing methyl methacrylate-methyl acrylate-methyl methacrylate block copolymer, amino-containing methyl methacrylate-ethyl acrylate-methyl methacrylate block copolymer, amino-containing methyl methacrylate-propyl acrylate-methyl methacrylate block copolymer, and amino-containing methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer.

3. The adhesive according to claim 1 or 2, characterized in that, The filler is silicon dioxide.

4. The adhesive according to any one of claims 1-3, characterized in that, The epoxy resin is any one or a combination of at least two of the following: alicyclic epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin, or glycidyl ester epoxy resin.

5. The adhesive according to any one of claims 1-4, characterized in that, The active diluent is any one or a combination of at least two of the following: 3-ethyl-3-oxabutane methanol, 4-ethyl-3-[(benzyloxy)methyl]oxetane, 3,3'-(oxybismethylene)bis(3-ethyl)oxetane, ethyl-3-((epoxyethylmethoxy)methyl)oxetane, 3-ethyl-3-[(ethylene oxide-2-methoxy)methyl]oxetane, 3,3-[1,4-butylbis(oxymethyl)]bis[3-ethyl]oxetane, 1,4-bis[(3-ethyl-3-oxetane-butylmethoxy)methyl]benzene, and 4,4'-hydroxymethylbiphenyl polymer oxetane.

6. The adhesive according to any one of claims 1-5, characterized in that, The cationic photoinitiator is any one or a combination of at least two of the following: triarylhexafluorophosphate thioonium salt, triarylhexafluoroantimonate thioonium salt, diarylhexafluorophosphate iodoonium salt, and diarylhexafluoroantimonate iodoonium salt.

7. The adhesive according to any one of claims 1-6, characterized in that, The cationic thermal initiator is any one or a combination of at least two of Vicbase TC3630, Vicbase TC3632, Vicbase TC3633 and Vicbase TC3634.

8. The adhesive according to any one of claims 1-7, characterized in that, The photosensitizer is any one or a combination of at least two of the following: 1-hydroxy-cyclohexyl-phenyl ketone, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, isopropylthioxanthone, 9,10-diethoxyanthracene, 9,10-dibutoxyanthracene, and N-vinylcarbazole.

9. The adhesive according to any one of claims 1-8, characterized in that, The thixotropic agent is any one or a combination of at least two of fumed silica, precipitated silica, and organobentonite.

10. An application of the adhesive as described in any one of claims 1-9, characterized in that, The adhesive is used for bonding and packaging optical components and microelectronic devices in the optical communication industry, or for packaging power modules in the automotive electronics and new energy industries.