An acoustic electronic component solder joint protection UV glue and a preparation method thereof

Abstract

The application provides a solder joint protection UV glue for acoustic electronic components and a preparation method thereof, and comprises the following raw materials in parts by weight: 50-60 parts of aromatic polyether polyurethane acrylate oligomer, 15-20 parts of active diluent, 3-5 parts of toughening agent, 2-6 parts of photoinitiator, 1-2 parts of adhesion promoter, and 1-5 parts of thixotropic agent; the aromatic polyether polyurethane acrylate oligomer is prepared by the following steps: first, aromatic diisocyanate is reacted with polyethylene glycol to generate an intermediate compound with isocyanate groups at both ends, and then the intermediate compound is reacted with a mixture of hydroxy acrylate and fluorovinyl alcohol compound; the loudspeaker lead solder joint protection UV glue prepared by using the main resin has good tensile shear fatigue resistance.

Description

Technical Field

[0001] This invention belongs to the field of acrylic UV adhesive technology, specifically relating to a UV adhesive for solder joint protection of acoustic electronic components and its preparation method. Background Technology

[0002] Solder joint protection UV adhesive is a single-component ultraviolet light curing adhesive that can quickly harden and produce strong protective properties under ultraviolet light. It has been widely used in electronic components, inductors, capacitors, circuit boards, ribbon cables, data cables, connectors, speakers and other products.

[0003] Because acoustic electronic components often face applications in confined spaces, high temperatures, high humidity, and low temperatures, UV-cured solder joint protectants are frequently required to perform well in these conditions. For example, patent CN113621339B discloses a photochromic solder joint protectant, its preparation method, and its application. The raw materials for preparing the solder joint protectant include a specific number of parts of monofunctional acrylate monomers, polyurethane acrylate oligomers, photoinitiators, epoxy resins, and UV-curing powders. Patent CN104531041B discloses a polyether-type polyurethane acrylate UV-curable adhesive and its preparation method. The adhesive of this invention is composed of the following raw materials in parts by weight: 20-70 parts of polyether-type polyurethane acrylate, 10-40 parts of auxiliary resin, 5-20 parts of ethylene acrylate rubber, 5-40 parts of acrylate monomers, 5-35 parts of isobornyl acrylate, 1-7 parts of photoinitiator, 1-5 parts of fumed silica, and 0.5-2 parts of silane coupling agent.

[0004] The above are common UV adhesives for solder joint protection. These adhesives, using one or more combinations of acrylic oligomers or modified acrylic oligomers as the main resin, have been modified or have other components added to achieve excellent properties such as high temperature resistance, low temperature resistance, and resistance to high temperature and humidity. However, because speaker leads are subjected to long-term periodic vibration, the UV protective adhesive at the solder joints at the lead ends is subjected to periodic stretching. Acrylic oligomers or modified acrylic oligomers have high glass transition temperatures, poor resin flexibility, or many heteroatoms in the molecular chain, poor heat resistance of the structure near the cross-linking stress points, and low carbon chain bond energy. These factors result in poor tensile shear fatigue resistance of the UV protective adhesive, making it prone to fatigue fracture and eventual failure. Therefore, conventional UV-cured acrylic or modified acrylic adhesives are unsuitable for protecting speaker lead solder joints. Thus, it is necessary to improve conventional UV adhesives for solder joint protection to develop an acoustic UV adhesive with excellent tensile shear fatigue resistance, such as a UV adhesive for protecting speaker lead solder joints. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a UV adhesive for protecting solder joints of acoustic electronic components and its preparation method. The main resin of the UV adhesive is an aromatic polyether polyurethane acrylate oligomer obtained by reacting aromatic diisocyanate with polyethylene glycol to generate an intermediate compound with isocyanate groups at both ends, and then reacting the intermediate compound with a mixture of hydroxyl acrylate and fluorinated vinyl alcohol compounds. The UV adhesive for protecting solder joints of speaker leads made with this main resin has good tensile shear fatigue resistance.

[0006] To achieve the above objectives, the following technical solution is adopted:

[0007] A UV adhesive for protecting solder joints of acoustic electronic components comprises the following raw materials in parts by weight: 50-60 parts of aromatic polyether polyurethane acrylate oligomer, 15-20 parts of reactive diluent, 3-5 parts of toughening agent, 2-6 parts of photoinitiator, 1-2 parts of adhesion promoter, and 1-5 parts of thixotropic agent; wherein the aromatic polyether polyurethane acrylate oligomer is prepared by reacting aromatic diisocyanate with polyethylene glycol to generate an intermediate compound with isocyanate groups at both ends, and then reacting the intermediate compound with a mixture of hydroxyl acrylate and fluorinated vinyl alcohol compounds.

[0008] Furthermore, the molar ratio of the polyethylene glycol, aromatic diisocyanate, hydroxy acrylate, and fluorovinyl alcohol compound is 1:2.08-2.12:1-1.05:1.3-1.5.

[0009] The main resin of this invention is an aromatic polyether polyurethane acrylate oligomer obtained by reacting aromatic diisocyanate with polyethylene glycol to generate an intermediate compound with isocyanate groups at both ends, and then reacting the intermediate compound with fluorinated vinyl alcohol compounds. By changing the molecular chain structure of the main resin, the tensile shear fatigue resistance of the UV adhesive for solder joint protection is improved.

[0010] The fluorovinyl alcohols are selected from one or a combination of two of 3,4,4-trifluoro-3-buten-1-ol and 2-fluoroallylol.

[0011] The hydroxy acrylate is selected from one or a combination of two or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0012] The aromatic diisocyanate is selected from one or a combination of two or more of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, and diphenylmethylene diisocyanate.

[0013] The number average molecular weight of the polyethylene glycol is 400-800.

[0014] The aromatic polyether polyurethane acrylate oligomer is prepared by a method comprising the following steps:

[0015] Under an inert atmosphere, polyethylene glycol, organic solvent, and polymerization inhibitor are added to a reactor, followed by the slow addition of aromatic diisocyanate and catalyst. The mixture is heated to react, and after the reaction is completed, it is cooled to room temperature. A mixture of hydroxy acrylate and fluorinated vinyl alcohol compounds is added, and the mixture is heated again to react. After the reaction is completed, it is distilled under reduced pressure to obtain aromatic polyether polyurethane acrylate oligomer.

[0016] The organic solvent is selected from one or a combination of two or more of ethyl acetate and butyl acetate; the catalyst is dibutyltin dilaurate, and the amount of catalyst used is 0.01-0.03 wt% of the total mass of aromatic diisocyanate and polyethylene glycol; the polymerization inhibitor is selected from one or a combination of two or more of hydroquinone, p-tert-butylcatechol, and 2,6-di-tert-butyl-p-methylphenol, and the amount of polymerization inhibitor used is 0.03-0.05 wt% of the mixture of hydroxy acrylate and fluorovinyl alcohol compounds;

[0017] The heating reaction is first heated to 80-100℃ and reacted for 1-3 hours, then cooled to 50-60℃ and reacted for another 1-3 hours; the second heating is heated to 60-80℃ and reacted for 1-3 hours (at which point the -NCO group disappears); the vacuum distillation is used to remove small molecule solvents.

[0018] The toughening agent is selected from one or a combination of two or more of silicone rubber, nitrile rubber, and acrylate rubber, and the average particle size of the toughening agent is 0.5-10 μm.

[0019] Preferably, the toughening agent is silicone rubber.

[0020] The adhesion promoter is an epoxy silane coupling agent, specifically selected from at least one of 3-(2,3-epoxypropoxypropyl)trimethoxysilane, 3-(2,3-epoxypropoxypropyl)triethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, 2-(3,4-epoxyhexane)ethyltrimethoxysilane, and 2-(3,4-epoxyhexane)ethyltriethoxysilane.

[0021] The reactive diluent is a reactive diluent with a functionality of 2-4, selected from one or a combination of two or more of the following: dimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, ethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, dipropylene glycol diacrylate, triethylene glycol diacrylate, and diethylene glycol diacrylate.

[0022] Furthermore, the reactive diluent is a mixture of a difunctional reactive diluent and a trifunctional reactive diluent in a weight ratio of 1-3:1.

[0023] The photoinitiator is selected from one or a combination of two or more of the following: thioxanthone photoinitiators, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, α,α-dimethoxy-α-phenylacetophenone, 1-hydroxy-cyclohexylbenzophenone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0024] The thixotropic agent is fumed silica. There are no particular limitations on the particle size of the fumed silica; any commonly used particle size in the field is acceptable, such as 200-300 μm for BET. 2 / g of fumed silica. Particle size range can be 5-25 nm.

[0025] The present invention also provides a method for preparing the above-mentioned UV adhesive for solder joint protection of acoustic electronic components, comprising the following steps:

[0026] 3) Preheat the toughening agent, add the adhesion promoter dropwise under stirring, continue stirring and reacting, and let it cool naturally to obtain a mixture for later use;

[0027] 4) Add the mixture obtained in step 1) to the aromatic polyether polyurethane acrylate oligomer and mix evenly. Add the reactive diluent, photoinitiator, thixotropic agent and remaining adhesion promoter, mix evenly, and degas under vacuum to obtain the above-mentioned UV adhesive for protecting the solder joints of the speaker leads.

[0028] The inventors discovered that adding adhesion promoters in batches and modifying toughening agents can synergistically improve the tensile shear fatigue resistance of UV adhesives by significantly enhancing the toughening agent's resistance to crosslinking stress points. This is speculated to be because modifying toughening agents with adhesion promoters helps the toughening agents disperse near the crosslinking stress points, absorbing, consuming, dispersing, or transferring the heat generated by periodic vibrations, thereby reducing the damage of heat to weak bonds.

[0029] Step 1) The preheating is to raise the temperature to 100-120℃ for 0.5-2 hours. The stirring speed is 1000-1500 rpm. The continued stirring reaction time is 10-15 minutes. The amount of adhesion promoter is 1-3 wt% of the total amount of adhesion promoter in steps 1) and 2).

[0030] The mixing process described in step 2) is carried out at room temperature.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] The main resin of the UV adhesive of the present invention is an aromatic polyether polyurethane acrylate oligomer obtained by reacting aromatic diisocyanate with polyethylene glycol to generate an intermediate compound with isocyanate groups at both ends, and then reacting the intermediate compound with a mixture of hydroxy acrylate and fluorinated vinyl alcohol compounds. The UV adhesive for protecting the solder joints of speaker leads made with this main resin has good tensile shear fatigue resistance. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0034] The silicone rubber powder SMP-594 was purchased from Shin-Etsu Chemical Co., Ltd., Japan. Shape: spherical; average particle size: 5μm; particle size distribution: 1-10μm.

[0035] The polyethylene glycol was purchased from Nantong Runfeng Petrochemical Co., Ltd., and its number average molecular weight was 800.

[0036] Fumed silica was purchased from Suzhou Youzirconium Nanomaterials Co., Ltd., with a BET of 240m. 2 / g.

[0037] Preparation of aromatic polyether polyurethane acrylate oligomers

[0038] Preparation Example 1

[0039] Under a nitrogen atmosphere, 1 mol of polyethylene glycol with a number average molecular weight of 800, 830 g of butyl acetate, and 0.1 g of hydroquinone were added to a reaction vessel. A mixture of 2.08 mol of diphenylmethane diisocyanate and 44 g of 0.3 wt% dibutyltin dilaurate solution (with butyl acetate as the solvent) was added dropwise. The mixture was heated to 80 °C and reacted for 2 h. After the reaction, the temperature was lowered to 50 °C and reacted for 2.5 h. After the reaction, the mixture was cooled to room temperature. A mixture of 1 mol of hydroxyethyl acrylate and 1.5 mol of 3,4,4-trifluoro-3-buten-1-ol was added. The temperature was raised to 70 °C again and reacted for 3 h. After the reaction, the small molecule solvent was removed by vacuum distillation to obtain the aromatic polyether polyurethane acrylate oligomer.

[0040] Preparation Example 2

[0041] The rest is the same as in Preparation Example 1, except that 3,4,4-trifluoro-3-buten-1-ol is replaced with an equimolar amount of 2-fluoroallyl alcohol.

[0042] Preparation Example 3

[0043] The rest is the same as in Preparation Example 1, except that the amount of 3,4,4-trifluoro-3-buten-1-ol used is 1.3 mol.

[0044] Preparation Example 4

[0045] The rest is the same as in Preparation Example 1, except that the amount of 3,4,4-trifluoro-3-buten-1-ol used is 1 mol.

[0046] Preparation Example 5

[0047] The rest is the same as in Preparation Example 1, except that the amount of 3,4,4-trifluoro-3-buten-1-ol used is 2 mol.

[0048] Comparative Preparation Example 1

[0049] The rest is the same as in Preparation Example 1, except that 3,4,4-trifluoro-3-buten-1-ol is replaced with an equimolar amount of hydroxyethyl acrylate.

[0050] Preparation of UV adhesive

[0051] Example 1

[0052] 1) Preheat 5 parts of silicone rubber powder SMP-594 at 100℃ for 1 hour, and add 0.05 parts of 3-(2,3-epoxypropoxypropyl)trimethoxysilane dropwise under stirring at 1000 rpm. Continue stirring and react for 10 minutes, and then cool naturally to obtain a mixture for later use.

[0053] 2) Add the mixture obtained in step 1) to 60 parts of the aromatic polyether polyurethane acrylate oligomer of Preparation Example 1 and mix well. Add 10 parts of diethylene glycol diacrylate, 10 parts of trimethylolpropane triacrylate, 5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 5 parts of fumed silica, and 1.95 parts of 3-(2,3-epoxypropoxypropyl)trimethoxysilane. Mix well and remove bubbles under vacuum to obtain the above-mentioned UV adhesive for protecting the solder joints of the speaker leads.

[0054] Examples 2-5

[0055] The rest is the same as in Example 1, except that the aromatic polyether polyurethane acrylate oligomers are the same as those obtained in Preparation Examples 2-5.

[0056] Example 6

[0057] The rest is the same as in Example 1, except that the amount of aromatic polyether polyurethane acrylate oligomer used in Example 1 is 50 parts.

[0058] Example 7

[0059] The rest is the same as in Example 1, except that the amount of silicone rubber powder SMP-594 is 3 parts.

[0060] Example 8

[0061] Everything else is the same as in Example 1, except that an equal amount of DuPont is used. Replacement for silicone rubber powder SMP-594.

[0062] Example 9

[0063] The rest is the same as in Example 1, except that the active diluent in step 2) consists of 15 parts diethylene glycol diacrylate and 5 parts trimethylolpropane triacrylate.

[0064] Example 10

[0065] The rest is the same as in Example 1, except that the active diluent in step 2) consists of 20 parts of diethylene glycol diacrylate.

[0066] Example 11

[0067] The rest is the same as in Example 1, except that the active diluent in step 2) consists of 20 parts of trimethylolpropane triacrylate.

[0068] Example 12

[0069] Add 5 parts of silicone rubber powder SMP-594 and 2 parts of 3-(2,3-epoxypropoxypropyl)trimethoxysilane to 60 parts of aromatic polyether polyurethane acrylate oligomer of Preparation Example 1 and mix evenly. Then add 10 parts of diethylene glycol diacrylate, 10 parts of trimethylolpropane triacrylate, 5 parts of light-2-hydroxy-2-methyl-1-phenyl-1-propanone, and 5 parts of fumed silica. Mix evenly and degas under vacuum to obtain the above-mentioned UV adhesive for protecting the solder joints of speaker leads.

[0070] Comparative Example 1

[0071] The rest is the same as in Example 1, except that the aromatic polyether polyurethane acrylate oligomer is the same as that obtained in Comparative Preparation Example 1.

[0072] The UV adhesive for protecting speaker lead solder joints prepared in the above embodiments and comparative examples was subjected to the following performance tests:

[0073] Curing speed: The above UV adhesive was applied in a 2mm thick layer. The UV curing machine was from Shenzhen Haitenaide Optoelectronics Technology Co., Ltd., model: HTBX-Ⅱ, light source: 365nm, power: 100mW / cm². 2 When the hardness reaches D60, it is considered to be fully cured. The hardness is tested according to ASTM D2240.

[0074] Tensile shear strength: The tensile shear strength was tested according to GB / T 7124-1986, the method for determining the tensile shear strength of adhesives, for aluminum / steel plates with an adhesive layer thickness of 0.6 mm.

[0075] Fatigue resistance test: Refer to GB / T 27595-2011 Test method for tensile and shear fatigue properties of structural adhesives. Substrate: aluminum plate / steel plate; stress amplitude: 5.5 MPa; frequency: 30 Hz; adhesive layer thickness: 0.6 mm; number of cycles: 10. 6 The tensile shear strength of the specimens after fatigue cycles was tested according to GB / T7124-1986, and the tensile shear strength retention rate was calculated.

[0076] Table 1

[0077] Example 1 39 23.4 97.5 Example 2 38 23.4 97.3 Example 3 30 22.1 94.2 Example 4 24 21.2 88.6 Example 5 77 23.8 98.8 Example 6 33 20.3 95.9 Example 7 38 23.7 96.1 Example 8 36 23.2 91.7 Example 9 45 22.5 95.4 Example 10 51 20.9 90.3 Example 11 12 27.0 89.6 Example 12 39 22.9 90.0 Comparative Example 1 36 24.6 72.8

[0078] As shown in Table 1, the present invention first reacts aromatic diisocyanate with polyethylene glycol to generate an intermediate compound with isocyanate groups at both ends, and then reacts the intermediate compound with a mixture of hydroxyl acrylate and fluorinated vinyl alcohol compounds to obtain an aromatic polyether polyurethane acrylate oligomer. The UV adhesive for protecting the solder joints of speaker leads made with this main resin has good tensile shear fatigue resistance.

[0079] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A UV adhesive for protecting solder joints of acoustic electronic components, characterized in that, The product comprises the following raw materials in parts by weight: 50-60 parts aromatic polyether polyurethane acrylate oligomer, 15-20 parts reactive diluent, 3-5 parts toughening agent, 2-6 parts photoinitiator, 1-2 parts adhesion promoter, and 1-5 parts thixotropic agent; the aromatic polyether polyurethane acrylate oligomer is prepared by reacting aromatic diisocyanate with polyethylene glycol to generate an intermediate compound with isocyanate groups at both ends, and then reacting the intermediate compound with a mixture of hydroxy acrylate and fluorinated vinyl alcohol compounds; the molar ratio of polyethylene glycol, aromatic diisocyanate, hydroxy acrylate, and fluorinated vinyl alcohol compounds is 1:2.08-2.12:1-1.05:1.3-1.

5.

2. The UV adhesive for solder joint protection of acoustic electronic components according to claim 1, characterized in that, The fluorovinyl alcohol compound is selected from one or a combination of two of 3,4,4-trifluoro-3-buten-1-ol and 2-fluoroallyl alcohol; the hydroxy acrylate is selected from one or a combination of two or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; the aromatic diisocyanate is selected from one or a combination of two or more of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, and phenylenediamine diisocyanate; and the number average molecular weight of the polyethylene glycol is 400-800.

3. The UV adhesive for protecting solder joints of acoustic electronic components according to claim 1, characterized in that, The aromatic polyether polyurethane acrylate oligomer is prepared by a method comprising the following steps: Under an inert atmosphere, polyethylene glycol, organic solvent, and polymerization inhibitor are added to a reactor, followed by the slow addition of aromatic diisocyanate and catalyst. The mixture is heated to react, and after the reaction is completed, it is cooled to room temperature. A mixture of hydroxy acrylate and fluorinated vinyl alcohol compounds is added, and the mixture is heated again to react. After the reaction is completed, it is distilled under reduced pressure to obtain aromatic polyether polyurethane acrylate oligomer.

4. The UV adhesive for protecting solder joints of acoustic electronic components according to claim 1, characterized in that, The toughening agent is selected from one or a combination of two or more of silicone rubber, nitrile rubber, and acrylate rubber, and the average particle size of the toughening agent is 0.5-10 μm.

5. The UV adhesive for solder joint protection of acoustic electronic components according to claim 1, characterized in that, The adhesion promoter is an epoxy silane coupling agent.

6. The UV adhesive for protecting solder joints of acoustic electronic components according to claim 5, characterized in that, The epoxy silane coupling agent is selected from at least one of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propyltriethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

7. The UV adhesive for solder joint protection of acoustic electronic components according to claim 1, characterized in that, The reactive diluent is a reactive diluent with a functionality of 2-4, selected from one or a combination of two or more of the following: dimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, dipropylene glycol diacrylate, triethylene glycol diacrylate, and diethylene glycol diacrylate.

8. The UV adhesive for solder joint protection of acoustic electronic components according to claim 7, characterized in that, The reactive diluent is a mixture of difunctional and trifunctional reactive diluents in a weight ratio of 1-3:

1.

9. A method for preparing the UV adhesive for solder joint protection of acoustic electronic components according to any one of claims 1-8, characterized in that, Includes the following steps: Preheat the toughening agent, add the adhesion promoter dropwise under stirring, continue stirring the reaction, and cool naturally to obtain a mixture for later use; Add the mixture obtained in step 1) to the aromatic polyether polyurethane acrylate oligomer and mix well. Add the reactive diluent, photoinitiator, thixotropic agent, and remaining adhesion promoter, mix well, and degas under vacuum to obtain the UV adhesive for solder joint protection of acoustic electronic components.

10. The method for preparing the UV adhesive for solder joint protection of acoustic electronic components according to claim 9, characterized in that, Step 1) The preheating is to raise the temperature to 100-120℃ for 0.5-2 hours. The stirring speed is 1000-1500 rpm. The stirring reaction time is 10-15 minutes. The amount of adhesion promoter is 1-3 wt% of the total amount of adhesion promoter in Step 1) and Step 2).