Resin composition and use thereof

Abstract

The embodiment of the present application provides a resin composition and application thereof, the resin composition comprises polyurethane acrylate and a curing monomer, the curing monomer comprises a compound containing a free radical polymerizable group and / or a compound containing a moisture curable group, and the weight average molecular weight of the curing monomer is greater than or equal to 300. The VOC content of the resin composition before and after curing is low, the sensitization risk is low, the bonding effect is good, the resin composition can be used as an adhesive in wearable devices such as earphones, reliable fixed bonding can be achieved, and the human body allergy problem caused by the adhesive in the prior art is solved to a certain extent.

Description

Technical Field

[0001] This application relates to the field of resin composition preparation technology, and in particular to a resin composition and its application. Background Technology

[0002] Wearable devices are currently very popular in the market. However, since wearing these devices involves direct contact with the skin, there is a risk of allergic reactions. Taking TWS (True Wireless Stereo) Bluetooth earphones as an example, with the increasing shipments and popularity of TWS earphones, some users have experienced skin allergies caused by them, with some even experiencing ear discharge and crusting. The main reason for these allergic reactions is the presence of acrylates in the earpiece. Acrylates mainly come from UV-curing adhesives or UV moisture-curing adhesives used to assemble and fix the various components of TWS earphones. The basic raw materials of these adhesives include oligomers, reactive monomers, and photoinitiators. Oligomers, containing unsaturated double bonds, serve as the main bonding material; reactive monomers are low-molecular-weight, low-viscosity materials that not only have good dilution properties but also participate in the reaction, increasing the cross-linking properties of the adhesive; and photoinitiators, as light energy absorbers, generate active fragments such as free radicals, cations, and anions that can initiate the polymerization of oligomers and monomers. However, in practical applications, some active monomers often fail to fully react and solidify. These active monomers have small molecular weights and are somewhat volatile, thus posing a risk of allergic reactions to the human body. Summary of the Invention

[0003] In view of this, this application provides a resin composition and its application. The resin composition has low VOC (Volatile Organic Compounds) content before and after curing, and good bonding effect. It can be used as an adhesive in wearable devices such as headphones. While achieving reliable fixing and bonding, it solves to some extent the problem of human allergies caused by adhesives in the prior art.

[0004] Specifically, in a first aspect of this application, a resin composition is provided, the resin composition comprising polyurethane acrylate and a curing monomer, the curing monomer comprising a compound containing free radical polymerizable groups and / or a compound containing moisture-curing groups, the weight average molecular weight of the curing monomer being greater than or equal to 300.

[0005] The resin composition provided in the first aspect of this application, by selecting curing monomers with a molecular weight greater than or equal to 300, can reduce the volatility of the resin composition before and after curing, thereby reducing the risk of allergic reactions to human skin. This allows the resin composition, when used as an adhesive in devices such as headphones, to achieve reliable bonding while also addressing, to some extent, the allergy problems caused by adhesives in the prior art. In some embodiments of this application, the resin composition includes curing monomers containing free radical polymerizable groups and moisture-curing groups, enabling the resin composition to simultaneously possess dual curing characteristics of UV curing and moisture curing, resulting in better curing effects.

[0006] In this application, the cured monomer may comprise one or more compounds, and the weight-average molecular weight of each component of the cured monomer, i.e., each compound, is greater than or equal to 300. In some embodiments of this application, the weight-average molecular weight of the cured monomer is greater than or equal to 500. A molecular weight greater than or equal to 500 makes it more difficult to penetrate the skin, thus better reducing the possibility of allergic reactions upon contact with human skin and better addressing user allergy issues. In some embodiments of this application, the weight-average molecular weight of the cured monomer may be 500-1000. By selecting a cured monomer with a suitable molecular weight, the viscosity of the resin composition can be controlled as much as possible while effectively reducing the risk of sensitization, allowing the cured monomer to play a diluting role to a certain extent.

[0007] In this embodiment, the weight-average molecular weight of the polyurethane acrylate can be greater than or equal to 500 and less than or equal to 5000. Choosing a weight-average molecular weight of ≥500 for the polyurethane acrylate helps reduce the risk of skin allergies to the resin composition; while choosing a weight-average molecular weight of less than or equal to 5000 for the polyurethane acrylate allows for better control of the overall viscosity and other properties of the resin composition, thereby reducing the dilution requirement for low molecular weight curing monomers and better adapting to the resin system in this application where the weight-average molecular weight of the curing monomers is greater than or equal to 300.

[0008] In this embodiment, the VOC content of the resin composition before and after curing is less than 20 mg / g. VOCs are volatile organic compounds that have a significant impact on human health. The World Health Organization (WHO) refers to organic compounds with a melting point below room temperature and a boiling point between 50°C and 260°C that have a certain degree of volatility as VOCs. The resin composition of this application has a low VOC content before and after curing, making it more environmentally friendly, beneficial to human health, and reducing the risk of allergies.

[0009] In this embodiment of the application, the non-volatile matter content of the resin composition before and after curing is greater than or equal to 98.5% by weight. A high non-volatile matter content by weight means a low volatile matter content and a low VOC content, which is beneficial to human health and reduces the risk of allergies.

[0010] In the embodiments of this application, the mass percentages of the polyurethane acrylate and the curing monomer in the resin composition are 50%-90% and 10%-50%, respectively.

[0011] In this embodiment, the resin composition further includes a photoinitiator. In this embodiment, the photoinitiator comprises 0.5%-5% by mass in the resin composition.

[0012] Polyurethane acrylate, as a prepolymer, is the main adhesive material, ensuring the bonding performance of the resin composition. The curing monomer is reactive and can react, increasing the crosslinking properties of the resin composition. The photoinitiator, as a light energy absorber, can generate active fragments that can initiate the polymerization of polyurethane acrylate and the curing monomer. Controlling the components of the resin composition within the aforementioned mass ratio range can achieve better curing and bonding effects.

[0013] In some embodiments of this application, the curing monomer includes compounds containing free radical polymerizable groups and / or compounds containing moisture-curing groups. In some embodiments of this application, the curing monomer includes compounds containing free radical polymerizable groups, but these compounds do not contain moisture-curing groups. In other embodiments of this application, the curing monomer includes compounds containing moisture-curing groups, but these compounds do not contain free radical polymerizable groups. In other embodiments of this application, the curing monomer simultaneously comprises a compound containing free radical polymerizable groups and a compound containing moisture-curing groups, and the resin composition comprises a curing monomer containing both free radical polymerizable groups and moisture-curing groups. In this embodiment, the compound containing free radical polymerizable groups and the compound containing moisture-curing groups may be the same compound, i.e., the compound simultaneously contains both free radical polymerizable groups and moisture-curing groups, meaning the free radical polymerizable groups and moisture-curing groups are provided by the same compound; alternatively, the compound containing free radical polymerizable groups and the compound containing moisture-curing groups may be different compounds. The compound containing free radical polymerizable groups contains only free radical polymerizable groups and does not contain moisture-curing groups; while the compound containing moisture-curing groups contains only moisture-curing groups and does not contain free radical polymerizable groups, meaning the free radical polymerizable groups and moisture-curing groups are provided by different compounds. The free radical polymerizable groups can react under UV light to cure the resin composition; while the moisture-curing groups can react with moisture to cure the resin composition.

[0014] In this application, the free radical polymerizable group can be an unsaturated double bond. In this application, the moisture-curing group can be one or more of terminal isocyanate groups and alkoxysilane groups. Both terminal isocyanate groups and alkoxysilane groups can react with moisture in the air for moisture curing. In some embodiments of this application, the curing monomer includes a compound containing a free radical polymerizable group and / or a compound containing a terminal isocyanate group. In other embodiments of this application, the curing monomer includes a compound containing a free radical polymerizable group and / or a compound containing an alkoxysilane group. In some embodiments of this application, the curing monomer includes a compound containing both a free radical polymerizable group and a terminal isocyanate group; in other embodiments of this application, the curing monomer includes a compound containing both a free radical polymerizable group and an alkoxysilane group.

[0015] Existing UV-curable adhesives can cure under ultraviolet light, but in practical applications, shaded areas not exposed to UV light cannot cure, resulting in a significant reduction in the mechanical properties of the cured adhesive. In this application, the curing monomer in the resin composition possesses both free radical polymerizable groups capable of UV curing and moisture-curing groups capable of moisture curing. This allows the resin to possess dual curing capabilities, allowing for both UV and moisture curing. Specifically, the resin composition can cure rapidly under light irradiation and cure in areas not exposed to sunlight using airborne moisture. Even after UV curing, the monomers continue to undergo moisture curing, thereby increasing the curing rate and solving the problem of shaded areas not curing during photopolymerization. The resin composition's dual UV and moisture curing properties ensure more complete curing and improve its bonding effect, especially for adhesive structures not fully irradiated by light, where the improvement in curing and bonding is even more significant.

[0016] In this embodiment, the isocyanate functionality of the compound containing free radical polymerizable groups and terminal isocyanate groups is greater than or equal to 2. The higher the isocyanate functionality, the better the curing can be achieved through the reaction of the isocyanate groups with water, etc.

[0017] In one embodiment of this application, the cured monomer comprises a compound represented by the following formula (1):

[0018]

[0019] In equation (1), m and n are positive integers. Specifically, m can be an integer between 2 and 20. n can be an integer greater than or equal to 1. For example, n can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0020] In another embodiment of this application, the cured monomer comprises a compound represented by the following formula (2):

[0021]

[0022] In this application, the photoinitiator can be any compound capable of absorbing energy of a certain wavelength in the ultraviolet region (250nm-420nm) to generate active fragments (such as free radicals, cations, anions, etc.), thereby initiating monomer polymerization, cross-linking, and curing. The photoinitiator enables the curing monomer to achieve rapid cross-linking and curing under light irradiation. In this application, the photoinitiator may specifically be one or more of α-hydroxy ketones, acylphosphine oxides, benzoylcarbamates, benzoyl, benzophenone, and oxime esters.

[0023] In this embodiment, the resin composition further includes thiols. The addition of thiols can improve the curing performance of the resin composition. Specifically, as a free radical chain transfer agent, the addition of thiols can increase the photosensitivity of the resin composition, enhance deep curing, and improve the curing performance of low-light regions. In this embodiment, the mass percentage of thiols in the resin composition is less than or equal to 3%. Controlling the amount of thiols added to 3% or less can improve the curing performance of the resin composition without causing storage instability due to excessive thiols content.

[0024] In the embodiments of this application, the thiol may be one or more of the following: pentaerythritol tetra(3-mercaptobutyrate) ester (CAS No. 31775-89-0), pentaerythritol tetra(3-mercaptopropionic acid) ester (CAS No. 7575-23-7), tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate (CAS No. 36196-44-8), and trimethylolpropane tris(3-mercaptopropionate) (CAS No. 33007-83-9).

[0025] In this embodiment of the application, the polyurethane acrylate may be prepared in the following manner:

[0026] In the presence of a catalyst and an antioxidant, a polyol and an isocyanate ethyl acrylate monomer are mixed and stirred at 40°C-100°C for 4-12 hours to obtain the polyurethane acrylate.

[0027] The polyurethane acrylate prepolymer material prepared by the above method can synthesize polyurethane prepolymers with low molecular weight and narrow molecular weight distribution in one step, which can reduce the number of processes and improve production efficiency.

[0028] In this application, the polyol can be various forms of polyol substances, such as one or more of polyester polyols, polycarbonate polyols, polyether polyols, polytetrahydrofuran ether diols, polycaprolactone polyols, or copolymers of the above polyols. By selecting the molecular weight of the polyol, the molecular weight of the resulting polyurethane acrylate can be better controlled at a low level.

[0029] In this embodiment of the application, the catalyst may be one or more of organobismuth compounds, organozinc compounds, and organotitanium compounds.

[0030] In this application, the antioxidant may be an alkylphenol antioxidant, specifically one or more of 2,6-di-tert-butyl-p-methylphenol (BHT), 2,4-di-tert-butylphenol, and o-tert-butylphenol (i.e., 2-tert-butylphenol).

[0031] In this embodiment of the application, the shear strength of the resin composition is greater than or equal to 1 MPa.

[0032] A second aspect of this application provides a method for preparing a resin composition, comprising the following steps:

[0033] The resin composition is obtained by mixing polyurethane acrylate and curing monomer, wherein the curing monomer includes compounds containing free radical polymerizable groups and / or compounds containing moisture-curing groups, and the weight average molecular weight of the curing monomer is greater than or equal to 300.

[0034] A third aspect of this application provides an adhesive comprising the resin composition described in the first aspect of this application.

[0035] A fourth aspect of this application provides a cured resin product, which is cured from the resin composition described in the first aspect of this application. In this embodiment, the curing includes ultraviolet light curing and / or moisture curing.

[0036] A fifth aspect of this application provides an adhesive structure comprising a first adhesive member, a second adhesive member, and an adhesive portion disposed between the first adhesive member and the second adhesive member. The adhesive portion comprises a cured product formed by curing the resin composition described in the first aspect of this application or the adhesive described in the third aspect, or a cured resin product described in the fourth aspect of this application. The first adhesive member and the second adhesive member can be any functional components that need to be bonded and fixed together.

[0037] In this embodiment of the application, the material of the first adhesive component can be plastic, metal, glass, or other materials, and the material of the second adhesive component can be plastic, metal, glass, or other materials.

[0038] This application also provides a device comprising the adhesive structure described in the fifth aspect of this application. This device can be various electronic devices or other devices requiring the adhesive structure. Specifically, electronic devices may include wearable devices (e.g., headphones, glasses, watches, bracelets, wristbands, helmets, headbands, etc.), mobile phones, tablets, laptops, portable computers, super mobile personal computers (MPCs), handheld computers, walkie-talkies, netbooks, POS machines, personal digital assistants (PDAs), dashcams, virtual reality devices, wireless USB flash drives, Bluetooth speakers, and in-vehicle products. Using the resin composition of this application embodiment as an adhesive to form the adhesive structure, the resin composition has dual UV and moisture curing properties, resulting in good curing and bonding effects, low volatility, and low allergy risk, which can improve the product competitiveness of electronic devices.

[0039] In some embodiments of this application, the device is a wearable device.

[0040] This application also provides embodiments of the resin composition for use in electronic devices. Specifically, the resin composition is used as an adhesive in electronic devices.

[0041] This application also provides a wearable device, which includes a housing and elements fixed to the housing by an adhesive, wherein the adhesive includes the adhesive described in the third aspect of this application. Attached Figure Description

[0042] Figure 1 A schematic diagram of the adhesive structure provided in the embodiments of this application;

[0043] Figure 2 This is a schematic diagram of the structure of a wearable device according to some embodiments of this application;

[0044] Figure 3 This is a schematic diagram illustrating the use of resin compositions for bonding and fixing in wearable devices in some embodiments of this application;

[0045] Figure 4 This is a schematic diagram showing the setup of the sample during the shear strength test of the resin composition of this application;

[0046] Figure 5 The infrared spectrum characterization of polyurethane A prepared in Example 1 of this application;

[0047] Figure 6 The infrared spectrum characterization diagram of polyurethane B prepared in Example 2 of this application;

[0048] Figure 7 The infrared spectrum characterization diagram is of polyurethane C prepared in Example 3 of this application. Detailed Implementation

[0049] The embodiments of this application will now be described in conjunction with the accompanying drawings.

[0050] Currently, UV-curing adhesives or UV moisture-curing adhesives used to fix components in wearable devices such as headphones often fail to achieve 100% curing of low molecular weight components during the curing process. This leads to the volatilization of these low molecular weight components when users wear these devices, causing allergic reactions. To reduce the risk of allergies when using wearable devices such as headphones, this application provides a resin composition with low VOC content before and after curing. This composition can be used as an adhesive in devices such as headphones, effectively solving the problem of allergies caused by adhesives while achieving reliable bonding.

[0051] The resin composition provided in this application includes polyurethane acrylate and a curing monomer. The curing monomer includes a compound containing a free radical polymerizable group and / or a compound containing a moisture-curing group. The weight average molecular weight of the curing monomer is greater than or equal to 300.

[0052] The resin composition provided in this application embodiment can reduce the volatility of the resin composition before and after curing by selecting curing monomers with a molecular weight greater than or equal to 300, thereby reducing the risk of allergic reactions to human skin. As a result, when the resin composition is used as an adhesive in devices such as headphones, it can achieve reliable fixation and bonding while solving the problem of human allergies caused by adhesives in the prior art to a certain extent.

[0053] In this application, the curing monomer may comprise one or more compounds, and the weight-average molecular weight of each component of the curing monomer, i.e., each compound, is greater than or equal to 300. In some embodiments of this application, the weight-average molecular weight of the curing monomer is greater than or equal to 500. According to the 500 Dalton rule, compounds with a molecular weight greater than or equal to 500 are more difficult to penetrate the skin. When the resin composition of this application is used as an adhesive, even if some curing monomers do not fully react and cure, the possibility of allergic reactions upon contact with human skin can be better reduced, thereby better solving the user's allergy problem. In some embodiments of this application, the weight-average molecular weight of the curing monomer is 500-1000, specifically, for example, 500, 600, 700, 800, 900, 1000, etc. By selecting a curing monomer with a suitable molecular weight, the viscosity of the resin composition can be controlled as much as possible while effectively reducing the risk of sensitization, allowing the curing monomer to play a dilution role to a certain extent.

[0054] In this application, the weight-average molecular weight of the polyurethane acrylate is greater than or equal to 500 and less than or equal to 5000. Choosing a weight-average molecular weight ≥500 for the polyurethane acrylate helps reduce the risk of skin allergies to the resin composition; while choosing a weight-average molecular weight less than or equal to 5000 allows for better control of the overall viscosity and other properties of the resin composition, ensuring the feasibility of dispensing processes and reducing the need for dilution of low molecular weight curing monomers, thus better adapting to resin systems in this application where the curing monomers have a molecular weight greater than or equal to 300. In some embodiments, the weight-average molecular weight of the polyurethane acrylate can be, for example, 500, 1000, 2000, 2500, 2700, 3000, 4000, 5000, etc. The resin composition in this application may contain one or more polyurethane acrylates. In this application, the PDI (Polymer Dispersity Index) of the polyurethane acrylate is less than or equal to 2. A lower PDI indicates higher material homogeneity, which is beneficial for improving the overall performance uniformity of the resin composition. All molecular weights of substances in this application are expressed in standard units g / mol.

[0055] In this application, the VOC content of the resin composition before and after curing is less than 20 mg / g. VOCs are volatile organic compounds that have a significant impact on human health. The World Health Organization (WHO) refers to organic compounds with a certain degree of volatility that have a melting point below room temperature and a boiling point between 50°C and 260°C as VOCs. The low VOC content of the resin composition before and after curing in this application is more environmentally friendly, beneficial to human health, and reduces the risk of allergies. In some embodiments of this application, the VOC content of the resin composition before and after curing is less than or equal to 18 mg / g. In some embodiments of this application, the VOC content of the resin composition before and after curing is less than or equal to 15 mg / g.

[0056] In this application, the weight content of non-volatile matter in the resin composition before and after curing is greater than or equal to 98.5%. In some embodiments, the weight content of non-volatile matter in the resin composition before and after curing is greater than or equal to 98.8%. A high weight content of non-volatile matter means a low weight content of volatile matter and a low VOC content, which is beneficial to human health and reduces the risk of allergies. A weight content of non-volatile matter in the resin composition before and after curing greater than or equal to 98.5% is equivalent to a weight content of volatile matter less than or equal to 15 mg / g.

[0057] In this embodiment, the mass percentages of polyurethane acrylate, curing monomer, and photoinitiator in the resin composition are 50%-90%, 10%-50%, and 0.5%-5%, respectively. Polyurethane acrylate, as a prepolymer, is the main adhesive material, ensuring the bonding performance of the resin composition. Controlling the mass percentage of polyurethane acrylate at 50%-90% ensures the adhesive properties of the resin composition. The curing monomer is reactive, capable of reacting and increasing the crosslinking of the resin composition, while also diluting the polyurethane acrylate. Controlling its mass percentage at 10%-50% effectively utilizes these functions. When the viscosity of the polyurethane acrylate is high, the amount of curing monomer can be increased. The photoinitiator, as a light energy absorption carrier, can generate active fragments capable of initiating the polymerization of polyurethane acrylate and curing monomer. Controlling the components of the resin composition within the above-mentioned weight ranges yields better curing and bonding effects. In some embodiments of this application, the mass percentage of polyurethane acrylate in the resin composition may be 50%, 60%, 70%, 80%, or 90%; the mass percentage of the curing monomer may be 10%, 20%, 30%, 40%, or 50%; and the mass percentage of the photoinitiator may be 0.5%, 1%, 1.5%, 2%, 3%, 4%, or 5%. In some embodiments, the mass ratio of polyurethane acrylate to curing monomer in the resin composition is 3-6:1. Specifically, for example, it is 3:1, 4:1, 5:1, or 6:1. Controlling the mass ratio of the two within the above range can enable the resin composition to obtain better overall performance.

[0058] In this application, the curing monomer includes compounds containing free radical polymerizable groups and / or compounds containing moisture-curing groups. The free radical polymerizable groups can undergo free radical polymerization under UV light irradiation, curing the resin composition; while the moisture-curing groups can react with moisture to cure the resin composition. In other embodiments of this application, the curing monomer includes compounds containing moisture-curing groups, but these compounds do not contain free radical polymerizable groups. In other embodiments of this application, the curing monomer simultaneously comprises a compound containing free radical polymerizable groups and a compound containing moisture-curing groups, and the resin composition comprises a curing monomer containing both free radical polymerizable groups and moisture-curing groups. In this embodiment, the compound containing free radical polymerizable groups and the compound containing moisture-curing groups may be the same compound, i.e., the compound simultaneously contains both free radical polymerizable groups and moisture-curing groups, meaning the free radical polymerizable groups and moisture-curing groups are provided by the same compound; alternatively, the compound containing free radical polymerizable groups and the compound containing moisture-curing groups may be different compounds. The compound containing free radical polymerizable groups contains only free radical polymerizable groups and does not contain moisture-curing groups; while the compound containing moisture-curing groups contains only moisture-curing groups and does not contain free radical polymerizable groups, meaning the free radical polymerizable groups and moisture-curing groups are provided by different compounds. The free radical polymerizable groups can react under UV light to cure the resin composition; while the moisture-curing groups can react with moisture to cure the resin composition. The resin composition includes a curing monomer containing free radical polymerizable groups and moisture-curing groups, which enables the resin composition to simultaneously possess dual curing characteristics of UV light curing and moisture curing, thereby obtaining better curing effect.

[0059] In this application, the free radical polymerizable group can be an unsaturated double bond. In this application, the moisture-curing group can be one or more of terminal isocyanate groups and alkoxysilane groups. Both terminal isocyanate groups and alkoxysilane groups can react with moisture in the air for moisture curing. In some embodiments of this application, the curing monomer includes a compound containing a free radical polymerizable group and / or a compound containing a terminal isocyanate group. In other embodiments of this application, the curing monomer includes a compound containing a free radical polymerizable group and / or a compound containing an alkoxysilane group. In some embodiments of this application, the curing monomer includes a compound containing both a free radical polymerizable group and a terminal isocyanate group; in other embodiments of this application, the curing monomer includes a compound containing both a free radical polymerizable group and an alkoxysilane group.

[0060] Existing UV-curable adhesives can cure under ultraviolet light, but in practical applications, shaded areas not exposed to UV light cannot cure, resulting in a significant reduction in the mechanical properties of the cured adhesive. In this application, the curing monomer molecular chains in the resin composition simultaneously possess free radical polymerizable groups capable of UV curing and moisture-curing groups capable of moisture curing. This enables the resin to possess dual curing capabilities, allowing for both UV and moisture curing. Specifically, the resin composition can cure rapidly under light irradiation and cure in areas not exposed to sunlight using airborne moisture. Even after UV curing, the monomers continue to undergo moisture curing, thereby increasing the curing rate and solving the problem of shaded areas failing to cure during photopolymerization. The resin composition's dual UV and moisture curing properties ensure more complete curing and improve its bonding effect, especially for adhesive structures not fully irradiated by light, where the improvement in curing and bonding is even more significant.

[0061] The specific chemical structure of the curing monomer in this application is not limited and can be various specific structures. The specific chemical structure of compounds containing both free radical polymerizable groups and terminal isocyanate groups, as well as curing monomers containing both free radical polymerizable groups and alkoxysilyl groups, is not limited. In the embodiments of this application, the isocyanate functionality of compounds containing both free radical polymerizable groups and terminal isocyanate groups can be greater than or equal to 2. The higher the isocyanate functionality, the better the curing can be achieved through the reaction of isocyanate groups with water, etc.

[0062] In one specific embodiment of this application, the compound containing both a free radical polymerizable group and a terminal isocyanate group includes the compound represented by the following formula (1):

[0063]

[0064] In equation (1), m and n are positive integers. Specifically, m can be an integer from 2 to 20, and n can be an integer greater than or equal to 1. For example, m can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.; n can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0065] In another embodiment of this application, the compound containing both a free radical polymerizable group and a terminal isocyanate group includes the compound represented by the following formula (2):

[0066]

[0067] The compound shown in formula (2) can be formed by reacting pentaerythritol triacrylate (PETIA) with isophorone diisocyanate (IPDI).

[0068] In this application, the photoinitiator can be any compound capable of absorbing energy of a certain wavelength in the ultraviolet region (250nm-420nm) to generate active fragments (such as free radicals, cations, anions, etc.), thereby initiating monomer polymerization, cross-linking, and curing. The photoinitiator enables the curing monomer to achieve rapid cross-linking and curing under light irradiation. The photoinitiator can be a low-oxygen-inhibiting, highly sensitive photoinitiator. Low-oxygen-inhibiting photoinitiators can achieve high reaction rates with lower photoinitiator content, thereby improving curing efficiency and curing effect. The resin composition may contain one or more photoinitiators. In some embodiments of this application, the photoinitiator may specifically include one or more of α-hydroxy ketones, acylphosphine oxides, benzoylcarbamates, benzoyl, benzophenone, and oxime esters. In some embodiments, the photoinitiator may include both α-hydroxy ketones and acylphosphine oxides.

[0069] In this embodiment, the resin composition further includes thiols. The addition of thiols can improve the curing performance of the resin composition. Specifically, as a free radical chain transfer agent, the addition of thiols can increase the photosensitivity of the resin composition, enhance deep curing, and improve the curing performance of low-light areas. In this embodiment, the mass percentage of thiols in the resin composition is less than or equal to 3%. Specifically, the mass percentage of thiols can be 0.4%-3%, for example, 0.4%, 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%. Controlling the amount of thiols added to 3% or less can improve the curing performance of the resin composition without causing storage instability due to excessive thiols content.

[0070] In the embodiments of this application, the resin composition may include one or more thiols. The specific selection of thiols is not limited. The thiols may be one or more of the following: pentaerythritol tetra(3-mercaptobutyrate) ester (CAS No. 31775-89-0), pentaerythritol tetra(3-mercaptopropionic acid) ester (CAS No. 7575-23-7), tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate (CAS No. 36196-44-8), and trimethylolpropane tris(3-mercaptopropionate) (CAS No. 33007-83-9).

[0071] In this application, the specific structure of the polyurethane acrylate is not limited. The polyurethane acrylate can be polymerized from polyols and isocyanate ethyl acrylate monomers. Specifically, the polyurethane acrylate can be prepared in the following manner:

[0072] In the presence of a catalyst and an antioxidant, a polyol and an isocyanate ethyl acrylate monomer are mixed and stirred at 40°C-100°C for 4-12 hours to obtain the polyurethane acrylate.

[0073] The above method allows for the one-step synthesis of polyurethane prepolymers with low molecular weight and narrow molecular weight distribution, reducing processing steps and improving production efficiency. However, the preparation of polyurethane acrylates is not limited to the above method; any method that achieves the desired polyurethane acrylate preparation is acceptable.

[0074] In this application, the polyol can be various forms of polyol substances, such as one or more of polyester polyols, polycarbonate polyols, polyether polyols, polytetrahydrofuran ether diols, polycaprolactone polyols, or copolymers of the above polyols. The polyol can be added in a slightly excess relative to the isocyanate ethyl acrylate monomer; for example, the amount of polyol added can be based on a stoichiometric ratio of hydroxyl to isocyanate groups of 1.05-1.2:1. The type of polyol determines the final molecular structure of the polyurethane acrylate.

[0075] In this embodiment, the catalyst can be one or more of organobismuth compounds, organozinc compounds, and organotitanium compounds. Organobismuth compounds, organozinc compounds, and organotitanium compounds are environmentally friendly catalysts that can reduce the risk of sensitization. Organobismuth compounds are organobismuth catalysts, specifically examples of which include bismuth isooctanoate, bismuth laurate, and bismuth neodecanoate. Organozinc compounds are organozinc catalysts, specifically examples of which include dimethyl zinc and diethyl zinc. Organotitanium compounds are organotitanium catalysts, specifically examples of which include titanate esters. The amount of catalyst added can be 100ppm-300ppm relative to the mass of the isocyanate ethyl acrylate monomer.

[0076] In this embodiment, the antioxidant may be an alkylphenol antioxidant, specifically one or more of 2,6-di-tert-butyl-p-methylphenol (BHT), 2,4-di-tert-butylphenol, and o-tert-butylphenol (i.e., 2-tert-butylphenol). The amount of antioxidant added may be 200 ppm to 1000 ppm relative to the mass of the ethyl isocyanate acrylate monomer.

[0077] In the embodiments of this application, the temperature of the polyurethane acrylate preparation reaction can be 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, etc., and the time can be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, etc.

[0078] The shear strength of the resin composition in this application embodiment is greater than or equal to 1 MPa, indicating that the resin composition has good adhesive properties. Shear strength is the ultimate strength generated when a material is sheared, reflecting the material's ability to resist shear slip. Numerically, it is equal to the tangential stress value on the shear plane, that is, the ratio of the shear force formed on the shear plane to the failure area. The higher the shear strength of the adhesive, the better the bonding effect.

[0079] This application also provides a method for preparing the above-mentioned resin composition, comprising the following steps:

[0080] The resin composition is obtained by mixing polyurethane acrylate, curing monomer and photoinitiator. The curing monomer includes compounds containing free radical polymerizable groups and / or compounds containing moisture-curing groups, and the weight average molecular weight of the curing monomer is greater than or equal to 300.

[0081] In some embodiments, thiols are also added during the mixing process. After the polyurethane acrylate, curing monomer, photoinitiator, and thiols are uniformly mixed, a degassing treatment can be further performed.

[0082] This application also provides an adhesive comprising the resin composition described above in this application embodiment. The adhesive of this application embodiment can be used for bonding and fixing various components to be bonded. It has low VOC content before and after curing, low sensitization risk, and strong bonding strength, making it suitable for use in electronic devices such as wearable devices, thereby enhancing the product competitiveness of electronic devices. When used for assembling and fixing components of electronic devices, the adhesive can be applied to the bonding surfaces of the components to be bonded, either by dispensing or by other means.

[0083] The shear strength of the adhesive in the embodiments of this application is greater than or equal to 1 MPa, indicating that the adhesive has good bonding performance.

[0084] This application also provides a resin cured product, which is formed by curing the resin composition described above in this application embodiment. In this application embodiment, curing may include ultraviolet light curing and / or moisture curing. The light curing conditions may be: UV light wavelength 365nm, irradiation energy 6000mJ / cm². 2 .

[0085] See Figure 1 This application also provides an adhesive structure 100, which includes a first adhesive member 10, a second adhesive member 20, and an adhesive portion 30 disposed between the first adhesive member 10 and the second adhesive member 20. The adhesive portion 30 includes a cured product formed by curing the resin composition or adhesive described above in this application embodiment. The first adhesive member 10 and the second adhesive member 20 can be any functional components that need to be bonded and fixed together, and their specific shape and structure are not limited.

[0086] In this embodiment of the application, the material of the first adhesive 10 can be plastic, metal, glass or other materials, and the material of the second adhesive 20 can be plastic, metal or glass or other materials.

[0087] This application also provides a device including the adhesive structure described in the embodiments of this application, wherein the device's components are assembled and fixed using the resin composition provided in the embodiments of this application. This device can be various electronic devices, or other devices that require assembly and fixation using adhesives, and thus, the adhesive structure is provided. Specifically, electronic devices can include wearable devices (e.g., headphones, glasses, watches, bracelets, wristbands, helmets, headbands, etc.), mobile phones, tablets, laptops, portable computers, super mobile personal computers (MPCs), handheld computers, walkie-talkies, netbooks, POS machines, personal digital assistants (PDAs), dashcams, virtual reality devices, wireless USB flash drives, Bluetooth speakers, and in-vehicle products. Using the resin composition of the embodiments of this application as an adhesive to form the adhesive structure results in good curing and bonding effects, low volatility, and low allergy risk, which can improve the product competitiveness of electronic devices and enhance the user's health experience.

[0088] See Figure 2 In some embodiments of this application, the device is a wearable device 200, which includes a housing 201 and functional components disposed inside the housing 201. Specifically, Figure 2 This is a schematic diagram of the structure of the wearable device 200 as an earphone. In the wearable device 200, the first adhesive component 10 and the second adhesive component 20 can be any functional components that need to be bonded together. For example, the first adhesive component 10 can be the housing of the wearable device, a carrier substrate, or a carrier bracket, etc. The second adhesive component 20 can be various wearable device components that need to be fixed to the housing or carrier substrate / carrier bracket, such as a microphone, sound outlet mesh, light guide post, inner lining bracket, distance sensor, etc. The resin composition of this application has low volatility. Using the resin composition of this application can reduce the risk of allergies when users wear wearable devices and improve the user's health experience.

[0089] See Figure 3 , Figure 3This is a schematic diagram illustrating the use of a resin composition for bonding and fixing in some embodiments of the wearable device 200 of this application. The housing 201 contains various functional components, including a sound-emitting mesh 2021, a light guide post 2022, and an inner lining support 2023. These functional components are fixed to the housing 201 via adhesive-formed connecting portions 203. The functional components can be directly or indirectly fixed to the housing 201 using adhesive. Indirect fixing, for example, may involve first fixing the functional component to a carrier substrate or carrier support using adhesive, and then fixing it to the housing; other forms are also possible. It is understood that in actual products, the adhesive-formed connecting portions 203 include, in addition to, [other components not specified in the original text]. Figure 3 The visible portion also includes the area located between the functional components and the housing. Figure 3 The invisible parts are not shown.

[0090] It should be noted that in this application, "-" indicates a numerical range, including two endpoint values. For example, "50%-90%" includes the two endpoint values ​​of 50% and 90%, as well as all values ​​between these two endpoint values.

[0091] The embodiments of this application will be further described below through multiple examples.

[0092] Example 1

[0093] Preparation of low molecular weight polyurethane acrylate A (weight average molecular weight 1344)

[0094] Place 100 ppm of catalyst (relative to 1 g AOI) and 200 ppm of antioxidant (relative to 1 g AOI) in a beaker, then add polycarbonate diol (synthesized from 2-methyl-2,4-pentanediol (MPD), 1,6-hexanediol (1,6-HD), and diethyl carbonate (DEC), with a number-average molecular weight Mn = 557 and a weight-average molecular weight Mw = 1293) into the beaker. After heating to 80°C, add ethyl isocyanate acrylate (AOI) monomer dropwise into the polycarbonate diol until the stoichiometric ratio of hydroxyl to isocyanate groups is 1.05-1.2:1, then stop adding ethyl isocyanate acrylate. After stirring for 4-12 hours, low molecular weight polyurethane acrylate A (referred to as polyurethane A) was prepared. The weight-average molecular weight Mw of the obtained polyurethane A was 1344; the number-average molecular weight Mn was 683; the viscosity was 3600; and the PDI (Polymer dispersity index) was 1.97.

[0095] Figure 5 This is the infrared spectrum characterization of polyurethane A prepared in Example 1 of this application. The horizontal axis represents wavelength, and the unit is cm. -1 ;from Figure 5It can be seen that the characteristic peak position of the isocyanate group -NCO is 2270 cm⁻¹. -1 The absence of a peak at 1640 cm⁻¹ indicates that the isocyanate group reaction is complete; additionally, at 1640 cm⁻¹... -1 Location, 810cm -1 The location of the C=C characteristic peak at 1550 cm⁻¹, and the position of the peak at 15 -1 The presence of a distinct NH characteristic peak at the position indicates the presence of C=C and NH in the polyurethane A molecule structure.

[0096] Example 2

[0097] Preparation of low molecular weight polyurethane acrylate B (weight average molecular weight 2503)

[0098] 100 ppm of catalyst (relative to 1 g AOI) and 200 ppm of antioxidant (relative to 1 g AOI) were placed in a beaker, followed by the addition of polycarbonate diol (synthesized from 2-methyl-2,4-pentanediol (MPD), 1,6-hexanediol (1,6-HD), and diethyl carbonate (DEC), with a number-average molecular weight Mn = 1083 and a weight-average molecular weight Mw = 2313). The mixture was heated to 80°C, and ethyl isocyanate acrylate (AOI) monomer was added dropwise to the polyol until the stoichiometric ratio of hydroxyl to isocyanate groups reached 1.05-1.2:1. The addition of ethyl isocyanate acrylate was then stopped. After stirring the reaction for 4-12 hours, low molecular weight polyurethane acrylate B (referred to as polyurethane B) was obtained. The obtained polyurethane B had a weight-average molecular weight Mw of 2503, a number-average molecular weight Mn of 1340, a viscosity of 27840, and a PDI of 1.87.

[0099] Figure 6 This is the infrared spectrum characterization of polyurethane B prepared in Example 2 of this application. The horizontal axis represents wavelength, and the unit is cm. -1 ;from Figure 6 It can be seen that the characteristic peak position of the isocyanate group -NCO is 2270 cm⁻¹. -1 The absence of a peak at 1640 cm⁻¹ indicates that the isocyanate group reaction is complete; additionally, at 1640 cm⁻¹... -1 Location, 810cm -1 The location of the C=C characteristic peak at 1550 cm⁻¹, and the position of the peak at 15 -1 The presence of a distinct NH characteristic peak at the position indicates the presence of C=C and NH in the polyurethane B molecule structure.

[0100] Example 3

[0101] Preparation of low molecular weight polyurethane acrylate C (weight average molecular weight 1338)

[0102] 100 ppm of catalyst (relative to 1 g AOI) and 200 ppm of antioxidant (relative to 1 g AOI) were placed in a beaker, followed by the addition of polycarbonate diol (synthesized from 2-methyl-2,4-pentanediol (MPD) and terephthalic acid, with a number-average molecular weight Mn = 641 and a weight-average molecular weight Mw = 1051). The mixture was heated to 80°C, and ethyl isocyanate acrylate (AOI) monomer was added dropwise to the polyol until the stoichiometric ratio of hydroxyl to isocyanate groups reached 1.05-1.2:1. The addition of ethyl isocyanate acrylate was then stopped. After stirring the reaction for 4-12 hours, low molecular weight polyurethane acrylate C (referred to as polyurethane C) was obtained. The obtained polyurethane C had a weight-average molecular weight Mw of 1338, a number-average molecular weight Mn of 936, a viscosity of 80610, and a PDI of 1.43.

[0103] Figure 7 This is the infrared spectrum characterization of polyurethane C prepared in Example 3 of this application. The horizontal axis represents wavelength, and the unit is cm. -1 ;from Figure 7 It can be seen that the characteristic peak position of the isocyanate group -NCO is 2270 cm⁻¹. -1 The absence of a peak at 1640 cm⁻¹ indicates that the isocyanate group reaction is complete; additionally, at 1640 cm⁻¹... -1 Location, 810cm -1 The location of the C=C characteristic peak at 1550 cm⁻¹, and the position of the peak at 15 -1 The presence of a distinct NH characteristic peak at the position indicates the presence of C=C and NH in the C molecular structure of polyurethane.

[0104] Example 4

[0105] Preparation of low molecular weight polyurethane acrylate D (weight average molecular weight 560)

[0106] 100 ppm of catalyst (relative to 1 g AOI) and 200 ppm of antioxidant (relative to 1 g AOI) were placed in a beaker, followed by the addition of polytetrahydrofuran ether diol (PTMG, number average molecular weight Mn = 340, weight average molecular weight Mw = 425). The mixture was heated to 80 °C, and ethyl isocyanate acrylate (AOI) monomer was added dropwise to the polyol until the stoichiometric ratio of hydroxyl to isocyanate groups reached 1.05-1.2:1. The addition of ethyl isocyanate acrylate was then stopped. After stirring the reaction for 4-12 h, low molecular weight polyurethane acrylate D (referred to as polyurethane D) was obtained. The obtained polyurethane D had a weight average molecular weight Mw of 560, a number average molecular weight Mn of 445, a viscosity of 7800, and a PDI of 1.26.

[0107] Example 5

[0108] Preparation of low molecular weight polyurethane acrylate E (weight average molecular weight 4860)

[0109] 100 ppm of catalyst (relative to 1 g AOI) and 200 ppm of antioxidant (relative to 1 g AOI) were placed in a beaker, followed by the addition of polycaprolactone diol (PCL, number-average molecular weight Mn = 3340, weight-average molecular weight Mw = 4560). The mixture was heated to 80°C, and ethyl isocyanate acrylate (AOI) monomer was added dropwise to the polyol until the stoichiometric ratio of hydroxyl to isocyanate groups reached 1.05-1.2:1. The addition of ethyl isocyanate acrylate was then stopped. After stirring the reaction for 4-12 hours, low molecular weight polyurethane acrylate E (referred to as polyurethane E) was obtained. The obtained polyurethane E had a weight-average molecular weight Mw of 4860, a number-average molecular weight Mn of 3578, a viscosity of 56000, and a PDI of 1.36.

[0110] The parameters of Examples 1-5 are listed in Table 1.

[0111] Table 1 Summary of parameters for Examples 1-5

[0112]

[0113] As shown in Table 1, Examples 1 to 5 of this application use polyol and ethyl isocyanate to prepare polyurethane acrylate with low molecular weight, suitable viscosity and narrow molecular weight distribution in a one-step process. The process is simple and efficient and can be industrialized.

[0114] Example 6

[0115] Preparation of resin composition 1 (using polyurethane A)

[0116] The low molecular weight polyurethane A synthesized in the above-mentioned examples was mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 80:20:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 1 was obtained, which is a low-volatility adhesive.

[0117] The resin composition 1 has a non-volatile component ratio of 99.36% before curing and a non-volatile component ratio of 98.70% after curing, with a shear strength of 1.25 MPa.

[0118] Example 7

[0119] Preparation of resin composition 2 (using polyurethane A)

[0120] The low molecular weight polyurethane A synthesized in the above-mentioned examples was mixed with UV moisture-curing monomer of formula (2) (molecular weight about 520), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 80:20:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 2 was obtained, which is the low volatility adhesive.

[0121] The resin composition 2 has a non-volatile component ratio of 99.20% before curing and a non-volatile component ratio of 98.50% after curing, with a shear strength of 1.21 MPa.

[0122] Example 8

[0123] Resin composition 3 was prepared by mixing two polyurethane acrylates, polyurethane A and polyurethane B.

[0124] The low molecular weight polyurethane A and polyurethane B synthesized in the above examples were mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 40:40:20:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 3 was obtained, which is a low volatile adhesive.

[0125] The resin composition 3 has a non-volatile component ratio of 99.45% before curing and a non-volatile component ratio of 99.29% after curing, with a shear strength of 1.23 MPa.

[0126] Example 9

[0127] Preparation of resin composition 4 (without thiols)

[0128] The low molecular weight polyurethane A synthesized in the above-mentioned embodiment is mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), and photoinitiator B (acylphosphine oxide) in a mass ratio of 80:20:0.5:0.5. After being loaded into a tube and degassed, resin composition 4 is obtained, which is a low volatile adhesive.

[0129] The resin composition 4 has a non-volatile component ratio of 99.17% before curing and a non-volatile component ratio of 98.93% after curing, with a shear strength of 1.19 MPa.

[0130] Example 10

[0131] Prepare resin composition 5 (compared to composition 1, the amount of thiol added is increased by 1 time).

[0132] The low molecular weight polyurethane A synthesized in the above-mentioned examples was mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 80:20:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 5 was obtained, which is the low volatility adhesive.

[0133] The resin composition 5 has a non-volatile component ratio of 99.40% before curing and a non-volatile component ratio of 98.82% after curing, with a shear strength of 1.35 MPa.

[0134] Example 11

[0135] Preparation of resin composition 6 (using polyurethane C)

[0136] The low molecular weight polyurethane C synthesized in the above-mentioned examples was mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 80:20:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 6 was obtained, which is a low-volatility adhesive.

[0137] The resin composition 6 has a non-volatile component ratio of 99.65% before curing and a non-volatile component ratio of 99.48% after curing, with a shear strength of 1.05 MPa.

[0138] Example 12

[0139] Preparation of resin composition 7 (using polyurethane D)

[0140] The low molecular weight polyurethane D synthesized in the above-mentioned examples was mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 80:20:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 7 was obtained, which is a low-volatility adhesive.

[0141] The resin composition 7 has a non-volatile component ratio of 99.10% before curing and a non-volatile component ratio of 98.90% after curing, with a shear strength of 1.05 MPa.

[0142] Example 13

[0143] Preparation of resin composition 8 (using polyurethane E)

[0144] The low molecular weight polyurethane D synthesized in the above-mentioned examples was mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 80:20:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 8 was obtained, which is a low volatile adhesive.

[0145] The resin composition 8 has a non-volatile component ratio of 99.61% before curing and a non-volatile component ratio of 98.48% after curing, with a shear strength of 1.2 MPa.

[0146] Example 14

[0147] Resin composition 9 was prepared by mixing two polyurethane acrylates, polyurethane A and polyurethane C.

[0148] The low molecular weight polyurethane A and polyurethane C synthesized in the above examples were mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 40:40:20:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 9 was obtained, which is a low volatile adhesive.

[0149] The resin composition 9 has a non-volatile component ratio of 99.49% before curing and a non-volatile component ratio of 99.14% after curing, with a shear strength of 1.63 MPa.

[0150] Example 15

[0151] Preparation of resin composition 10

[0152] The low molecular weight polyurethane A and polyurethane C synthesized in the above examples were mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 40:40:20:0.5:0.5:1. After being loaded into a glue tube and degassed, resin composition 10 was obtained, which is a low volatile adhesive.

[0153] The resin composition 10 has a non-volatile component ratio of 99.30% before curing and a non-volatile component ratio of 99.62% after curing, with a shear strength of 1.98 MPa.

[0154] Example 16

[0155] Preparation of resin composition 11

[0156] The low molecular weight polyurethane A and polyurethane C synthesized in the above examples were mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol B (pentaerythritol tetrakis(3-mercaptopropionic acid) ester) in a mass ratio of 40:40:20:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 11 was obtained, which is a low volatile adhesive.

[0157] The resin composition 11 has a non-volatile component ratio of 99.60% before curing and a non-volatile component ratio of 99.19% after curing, with a shear strength of 2.18 MPa.

[0158] Example 17

[0159] Preparation of resin composition 12

[0160] The low molecular weight polyurethane A and polyurethane C synthesized in the above examples were mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol B (pentaerythritol tetrakis(3-mercaptopropionic acid) ester) in a mass ratio of 40:40:20:0.5:0.5:1. After being loaded into a glue tube and degassed, resin composition 12 was obtained, which is a low volatile adhesive.

[0161] The resin composition 12 has a non-volatile component ratio of 99.53% before curing and a non-volatile component ratio of 98.96% after curing, with a shear strength of 2.34 MPa.

[0162] Example 18

[0163] Preparation of resin composition 13

[0164] The low molecular weight polyurethane A synthesized in the above-mentioned examples was mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 180:20:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 13 was obtained, which is a low volatile adhesive.

[0165] The resin composition 13 has a non-volatile component ratio of 99.18% before curing and a non-volatile component ratio of 99.50% after curing, with a shear strength of 1.17 MPa.

[0166] Example 19

[0167] Preparation of resin composition 14

[0168] The low molecular weight polyurethane A synthesized in the above-mentioned examples was mixed with UV moisture-curing monomer (molecular weight 600) of formula (1), photoinitiator A (α-hydroxy ketone), photoinitiator B (acylphosphine oxide), and thiol A (pentaerythritol tetra(3-mercaptobutyric acid) ester) in a mass ratio of 50:40:0.5:0.5:0.5. After being loaded into a glue tube and degassed, resin composition 14 was obtained, which is a low volatile adhesive.

[0169] The resin composition 14 has a non-volatile component ratio of 99.40% before curing and a non-volatile component ratio of 99.05% after curing, with a shear strength of 1.06 MPa.

[0170] Comparative Example 1

[0171] The low molecular weight polyurethane A synthesized in Example 1 of this application was mixed with isobornyl acrylate (IBOA, a UV-curable monomer with a molecular weight of 208), photoinitiator A (α-hydroxy ketone), and photoinitiator B (acylphosphine oxide) in a mass ratio of 80:20:0.5:0.5. After being loaded into a tube, the mixture was degassed to obtain the resin composition of Comparative Example 1.

[0172] Comparative Example 2

[0173] 100 ppm of catalyst (relative to 1 g IPDI) was placed in a beaker, followed by the addition of polyester diol (synthesized from adipic acid (AA) and 2-methyl-2,4-pentanediol (MPD), with a number-average molecular weight Mn = 1890 and a weight-average molecular weight Mw = 2850) and isobornyl acrylate monomer (IBOA) diluted into the beaker. The mixture was heated to 80°C, and isophorone diisocyanate (IPDI) was added dropwise to the polyol until the stoichiometric ratio of hydroxyl to isocyanate groups was 1:1.2-1.4. The addition of isophorone diisocyanate was then stopped. After stirring the reaction for 4-12 hours, hydroxyethyl acrylate (HEA) was added for end-capping to obtain high molecular weight polyurethane acrylate F (referred to as polyurethane F). The polyurethane F had a weight-average molecular weight Mw of 34000, a number-average molecular weight Mn of 17282, a viscosity of 25000, and an IPDI of 1.97. The prepared polyurethane acrylate F with a weight average molecular weight of 34,000 was mixed with isobornyl acrylate (IBOA, a UV-curable monomer with a molecular weight of 208), photoinitiator A (α-hydroxy ketone), and photoinitiator B (acylphosphine oxide) in a mass ratio of 52:48:0.5:0.5. After being loaded into a tube, the mixture was degassed to obtain the resin composition of Comparative Example 2.

[0174] In this application, see Figure 4The shear strength test method is as follows: A standard glass sample measuring 100mm × 25.4mm × 2.5mm and a polybutylene terephthalate (PBT) sample are used. The glass sample and PBT sample are bonded together using the adhesive samples described in this application. The bonding surface is 12.7mm × 25.4mm. A 0.12mm thick spacer is used to control the adhesive layer thickness. The sample is cleaned with anhydrous ethanol before bonding. The shear strength is tested at 6000mJ / cm². 2 After irradiation with 365nm UV light, a universal tensile testing machine was used to stretch the sample along its length at a speed of 10mm / min. Additionally, the mass percentage of non-volatile components in the resin compositions of the examples and comparative examples before and after UV curing was determined according to GB / T 2793-1995 "Determination of Non-Volatile Content in Adhesives", specifically at a test temperature of 150℃ and a test time of 30min.

[0175] The data values ​​for Examples 6-12 are listed in Table 2, and the data values ​​for Examples 13-19 and the comparative examples are listed in Table 3.

[0176] Table 2 Summary of Experimental Data from Examples 6-12

[0177]

[0178] Table 3 Summary of Experimental Data from Examples 13-19

[0179]

[0180]

[0181] As shown in Tables 2 and 3, the mass percentage of non-volatile components in the resin compositions of this application embodiment before and after curing is higher than that in the comparative resin compositions, specifically exceeding 98.5%. This indicates that the VOC content and allergenicity of the resin compositions of this application embodiment are low before and after curing. Therefore, when the resin compositions of this application embodiment are used in wearable devices such as headphones, the risk of allergies to the human body can be reduced, product competitiveness can be improved, and user experience can be enhanced. Tables 2 and 3 also show that the resin compositions of this application embodiment have high shear strength, all exceeding 1 MPa, and can achieve good bonding effects. The resin compositions of this application embodiment, while possessing good bonding effects, have low VOC content and low allergenicity risk, making them suitable for the assembly and fixation of components in wearable devices. Furthermore, comparing resin compositions 1, 4, and 5, the addition of thiol can improve the curing performance and shear strength of the resin compositions. Comparing resin compositions 9 and 10, and resin compositions 11 and 12, it can be seen that increasing the amount of thiol to a certain extent is beneficial for improving curing performance. A comparison of resin compositions 9, 10, 11 and 12 also shows that thiol B is more beneficial than thiol A in improving the curing performance of the resin. However, the inventors found that the storage stability of resin compositions 11 and 12 is lower than that of resin compositions 9 and 10.

[0182] The hardness, elongation at break, and tensile strength of the resin compositions 1, 9, and 10 obtained in the examples were tested after curing, and the results are listed in Table 4.

[0183] The Shore hardness test is performed by preparing a 3mm thick disc from the resin composition and measuring its hardness using a Shore hardness tester. Elongation at break and tensile strength are measured by preparing a 0.2mm thick film from the resin composition according to ASTM D638. Elongation at break is the ratio of the displacement at break to the original length, expressed as a percentage (%). Tensile strength characterizes the material's resistance to maximum uniform plastic deformation.

[0184] The shear strength of resin compositions 1, 9, and 10 obtained in the examples was measured before and after curing, wherein the shear strength after curing included a value of 6000 mJ / cm. 2 The initial shear strength after curing with 365nm UV light, the shear strength after curing with UV light and then at room temperature for 7 days (7×24 hours), and the shear strength after curing with pure moisture at room temperature for 2 days (2×24 hours) are measured. The results are listed in Table 4.

[0185] Table 4. Performance test results of the resin composition

[0186]

[0187] As can be seen from the results in Table 4, the resin composition of this application embodiment can achieve properties such as hardness, elongation at break, tensile strength, and shear strength that meet the requirements of conventional adhesive products. The results in Table 4 also show that the resin composition of this application embodiment has dual UV light / moisture curing characteristics, with moisture curing compensating for the incompleteness of light curing.

[0188] The volatile matter content of the resin compositions before and after curing was determined by GC-MS (gas chromatography-mass spectrometry), and the non-volatile matter content of the resin compositions before and after curing was determined by thermogravimetric analysis (test temperature 150℃ / test time 30min), and then converted into volatile matter content. The determination results of resin compositions 1, 9, 10, and Comparative Example 2 in the embodiments of this application are listed in Table 5.

[0189] Table 5. Results of volatile content determination of resin composition before and after curing

[0190]

[0191] As shown in Table 5, the volatile content of the resin composition in this application before curing is significantly lower than that of the resin composition in Comparative Example 2 before curing. Furthermore, the volatile content of the resin composition in this application after UV curing and after pure moisture curing is also lower than that of the resin composition in Comparative Example 2 after UV curing and pure moisture curing, respectively. In addition, because the resin composition in Comparative Example 2 has a higher volatile content after curing, it emits a faint odor, while the resin composition in this application has a lower volatile content and no odor after curing, which improves the user experience of end products using the resin composition in this application.

Claims

1. A resin composition, characterized by comprising: The resin composition comprises a polyurethane acrylate and a curing monomer, the curing monomer has a weight average molecular weight of 500-1000, and the curing monomer comprises a compound represented by the following formula (1): In formula (1), m and n are positive integers. Alternatively, the curing monomer comprises a compound represented by the following formula (2): The weight average molecular weight of the polyurethane acrylate is greater than or equal to 500 and less than or equal to 5000, the VOC content of the resin composition before and after curing is less than 20 mg / g, and the shear strength of the resin composition is greater than or equal to 1 MPa.

2. The resin composition according to claim 1, characterized by The non-volatile matter content of the resin composition before and after curing is greater than or equal to 98.5%.

3. The resin composition according to claim 1, characterized by In the resin composition, the mass ratio of the polyurethane acrylate and the curing monomer is 50%-90% and 10%-50%, respectively.

4. The resin composition according to claim 1, characterized by The resin composition further comprises a photoinitiator.

5. The resin composition according to claim 4, characterized by In the resin composition, the mass ratio of the photoinitiator is 0.5%-5%.

6. The resin composition according to claim 1, characterized by The resin composition further comprises a thiol.

7. The resin composition according to claim 6, characterized by In the resin composition, the mass ratio of the thiol is less than or equal to 3%.

8. The resin composition according to claim 4 or 5, characterized by The photoinitiator comprises one or more of α-hydroxy ketone, acyl phosphine oxide, benzoyl formate, benzoin, benzophenone, and oxime ester photoinitiator.

9. The resin composition according to claim 6 or 7, characterized by The thiol comprises one or more of pentaerythritol tetra(3-mercapto butyric acid) ester, pentaerythritol tetra(3-mercapto propionic acid) ester, tris[2-(3-mercapto propionyloxy)ethyl] isocyanurate, and trimethylolpropane tri(3-mercapto propionate).

10. The resin composition according to claim 1, characterized by The polyurethane acrylate is prepared in the following manner: The polyol and the isocyanate acrylate monomer are mixed in the presence of a catalyst and an antioxidant, and stirred and reacted at 40-100°C for 4-12 hours to obtain the polyurethane acrylate.

11. A method for producing a resin composition, characterized by comprising: The steps include: The polyurethane acrylate and the curing monomer are mixed to obtain the resin composition, the curing monomer has a weight average molecular weight of 500-1000, and the curing monomer comprises a compound represented by the following formula (1): In formula (1), m and n are positive integers. Alternatively, the curing monomer comprises a compound represented by the following formula (2): The weight average molecular weight of the polyurethane acrylate is greater than or equal to 500 and less than or equal to 5000, the VOC content of the resin composition before and after curing is less than 20 mg / g, and the shear strength of the resin composition is greater than or equal to 1 MPa.

12. An adhesive characterized by, The adhesive comprises the resin composition of any one of claims 1-10.

13. A resin cured product, characterized by, The resin cured product is cured from the resin composition of any one of claims 1-10.

14. The resin cured product according to claim 13, characterized by The curing comprises ultraviolet light curing and / or moisture curing.

15. An adhesive structure, characterized by The bonding structure comprises a first bonding member, a second bonding member, and a bonding portion arranged between the first bonding member and the second bonding member, and the bonding portion comprises a cured product cured from the resin composition of any one of claims 1-10.

16. An apparatus, comprising: The device uses the resin composition of any one of claims 1-10 or comprises the bonding structure of claim 15.

17. The apparatus of claim 16, wherein, The device is a wearable device.

18. Use of the resin composition according to any one of claims 1 to 10 in an electronic device.

19. Use according to claim 18, characterized in that, The resin composition is used as an adhesive in an electronic device.

20. A wearable device, comprising: The wearable device includes a housing and an element fixed to the housing by an adhesive, the adhesive including the adhesive of claim 12.

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