Monomer-free UV-moisture dual-curing adhesive and preparation method thereof

Abstract

The invention discloses a monomer-free UV (ultraviolet)-moisture dual-curing adhesive and a preparation method thereof. The monomer-free UV-moisture dual-curing adhesive is prepared from UV-moisture dual-curing resin, monofunctional polyurethane acrylate, a free radical photoinitiator and an auxiliary agent, the mass part of the UV-moisture dual-curing resin is 20 to 80 parts; the mass part of the monofunctional polyurethane acrylate is 0 to 40 parts; the mass part of the free radical photoinitiator is 0-5; the mass part of the auxiliary agent is 0-11; wherein the content of each component is not 0 part. The method can be applied to wearable electronic equipment and handheld electronic equipment to solve the problem that the electronic products are prone to sensitization when making contact with human skin for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, and in particular to a monomer-free UV-moisture dual-curing adhesive and a preparation method thereof. Background Art

[0002] With the rapid advancement of electronic technology, smart electronic products have become an indispensable part of our daily lives. Especially for wearable devices and handheld electronic devices, which are in contact with the user's skin for a long time, the safety of adhesives used in the production process is particularly important. If these adhesives contain allergenic ingredients, such as incompletely cured monomers and reactive diluents, they may cause skin allergic reactions, manifested as itching, pain, erythema or edema. In addition, considering that some structures of these devices may contain irregular areas or parts that are not convenient for ultraviolet radiation, a single UV-curing adhesive is not sufficient to meet their bonding needs. Therefore, it is urgent to propose a monomer-free UV-moisture dual-curing adhesive with low viscosity, low volatility, low sensitization, low shrinkage, aging resistance and universal bonding to a variety of substrates and its preparation method. It is very necessary to apply it to the production and manufacturing of wearable electronic devices and handheld electronic devices, which is of great significance to the sustainable development of smart electronic devices. Summary of the invention

[0003] The purpose of the present invention is to provide a monomer-free UV-moisture dual-curing adhesive and a preparation method thereof, which can be applied to wearable electronic devices and handheld electronic devices to solve the problem that such electronic products are prone to allergic reactions due to long-term contact with human skin.

[0004] In order to solve the above technical problems, the present invention provides a monomer-free UV-moisture dual-curing adhesive, comprising: a UV-moisture dual-curing resin, a monofunctional polyurethane acrylate, a free radical photoinitiator and an auxiliary agent;

[0005] The mass fraction of the UV-moisture dual-curing resin is 20 to 80 parts; the mass fraction of the monofunctional polyurethane acrylate is 0 to 40 parts; the mass fraction of the free radical photoinitiator is 0 to 5 parts; the mass fraction of the auxiliary agent is 0 to 11 parts; wherein each component is not 0 parts.

[0006] Furthermore, the UV-moisture dual-curing resin is obtained by reacting a first isocyanate with a first hydroxyl-containing acrylate in the presence of a first catalyst; wherein the molar equivalent ratio of the first isocyanate to the first hydroxyl-containing acrylate is 2:1 to 4:1, and the mass of the first catalyst accounts for 0.01 to 0.03% of the total mass.

[0007] Furthermore, the first isocyanate is a trifunctional isocyanate, and its structure contains three first isocyanate groups.

[0008] Furthermore, the first hydroxyl-containing acrylate includes any one or more of a first hydroxyethyl acrylate, a first hydroxyethyl methacrylate, a first hydroxypropyl acrylate, a first hydroxypropyl methacrylate, and a first hydroxybutyl acrylate.

[0009] Furthermore, the first catalyst includes any one or more of a first organic tin catalyst and a first organic bismuth catalyst.

[0010] Furthermore, the monofunctional polyurethane acrylate is obtained by reacting a second isocyanate, a monohydric alcohol, and a second hydroxyl-containing acrylate in the presence of a second catalyst and an inhibitor; wherein the molar ratio of the second isocyanate, the monohydric alcohol, and the second hydroxyl-containing acrylate is 0.08:0.5:0.5-1.15:1.5:1.5, and the content of the second catalyst and the inhibitor each accounts for 0.01-0.03% of the total mass.

[0011] Furthermore, the second isocyanate is a difunctional isocyanate, and its structure contains two second isocyanate groups.

[0012] Furthermore, the monohydric alcohol includes any one or more of methanol, ethanol, n-propanol and n-butanol.

[0013] Furthermore, the second hydroxyl-containing acrylate includes any one or more of a second hydroxyethyl acrylate, a second hydroxyethyl methacrylate, a second hydroxypropyl acrylate, a second hydroxypropyl methacrylate, and a second hydroxybutyl acrylate.

[0014] Furthermore, the second catalyst includes any one or more of a second organic tin catalyst and a second organic bismuth catalyst.

[0015] Furthermore, the polymerization inhibitor includes any one or more of hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol and anthraquinone.

[0016] Further, the free radical photoinitiator includes any one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-isopropylthioxanthone, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone and benzoin dimethyl ether.

[0017] Furthermore, the auxiliary agent includes a leveling agent, a coupling agent and a filler;

[0018] The mass fraction of the leveling agent is 0-1 parts, the mass fraction of the coupling agent is 0-5 parts, and the mass fraction of the filler is 0-5 parts; wherein each component is not 0 parts.

[0019] In addition, the present invention also provides a method for preparing a monomer-free UV-moisture dual-curing adhesive. The method for preparing the monomer-free UV-moisture dual-curing adhesive as described above specifically includes the following steps:

[0020] Weigh the ingredients of the formula content;

[0021] Mix the UV-moisture dual-curing resin and the monofunctional polyurethane acrylate and stir well;

[0022] Add free radical photoinitiator and disperse evenly;

[0023] Add the auxiliary agent, mix and stir evenly at room temperature to obtain the monomer-free UV-moisture dual-curing adhesive.

[0024] Furthermore, the UV-moisture dual-curing resin is prepared in the following manner:

[0025] Add the first isocyanate and the dehydrated first hydroxyl-containing acrylate into a first designated container;

[0026] Start stirring, raise the temperature to 60-80°C, and react for 0.4-0.6h;

[0027] Add the first catalyst, maintain the temperature at 70-80°C, and react for 1-2 hours;

[0028] The NCO content in the system is measured, and when the NCO content in the system reaches a first predetermined value, the material is discharged at a lower temperature to obtain the desired UV-moisture dual-curing resin.

[0029] Furthermore, the monofunctional polyurethane acrylate is prepared in the following manner:

[0030] Take the second isocyanate and the second catalyst and add them into the second designated container, and start stirring;

[0031] Add anhydrous monohydric alcohol, raise the temperature to 60-80°C, and react for 0.4-0.6h;

[0032] Add the dehydrated second hydroxyl-containing acrylate and the polymerization inhibitor, maintain the temperature at 60-70° C., and react for 1-2 hours;

[0033] The NCO content in the system is measured, and when the NCO content in the system reaches a second predetermined value, the temperature is reduced to room temperature and the material is discharged to obtain the desired monofunctional polyurethane acrylate.

[0034] Through the above technical solution, the present invention has the following beneficial effects:

[0035] The present invention uses UV-moisture dual-curing resin as the main resin and uses self-made monofunctional polyurethane acrylate (i.e. low-viscosity monofunctional polyurethane acrylate) as the diluent. The prepared monomer-free UV-moisture dual-curing adhesive has low viscosity, low volatility, low sensitization, low shrinkage, aging resistance, and good bonding to various substrates. Since the monomer-free UV-moisture dual-curing adhesive of the present invention does not introduce monomers and active diluents into the formula, but uses self-made monofunctional polyurethane acrylate, it can reduce viscosity and increase bonding strength and toughness while also reducing the risk of sensitization. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Flow chart of a method for preparing a monomer-free UV-moisture dual-curing adhesive according to an embodiment of the present invention;

[0037] Figure 2 This is a flow chart of a method for preparing a UV-moisture dual-curing resin in a method for preparing a monomer-free UV-moisture dual-curing adhesive in one embodiment of the present invention;

[0038] Figure 3 The present invention is a flowchart of a method for preparing monofunctional polyurethane acrylate in a method for preparing a monomer-free UV-moisture dual-curing adhesive in one embodiment of the present invention. DETAILED DESCRIPTION

[0039] A monomer-free UV-moisture dual-curing adhesive and a method for preparing the same will be described in more detail below in conjunction with the accompanying drawings, wherein preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art may modify the present invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as being generally known to those skilled in the art and not as a limitation of the present invention.

[0040] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in illustrating the purpose of the embodiments of the present invention.

[0041] The embodiment of the present invention provides a monomer-free UV-moisture dual-curing adhesive, comprising: a UV-moisture dual-curing resin, a monofunctional polyurethane acrylate, a free radical photoinitiator and an auxiliary agent.

[0042] Specifically, the mass fraction of the UV-moisture dual-curing resin is 20 to 80 parts; the mass fraction of the monofunctional polyurethane acrylate is 0 to 40 parts; the mass fraction of the free radical photoinitiator is 0 to 5 parts; the mass fraction of the auxiliary agent is 0 to 11 parts; wherein each component is not 0 parts.

[0043] In this embodiment, the UV-moisture dual-curing resin is obtained by reacting a first isocyanate with a first hydroxyl-containing acrylate in the presence of a first catalyst; wherein the molar equivalent ratio of the first isocyanate to the first hydroxyl-containing acrylate is 2:1 to 4:1, and the mass of the first catalyst accounts for 0.01 to 0.03% of the total mass.

[0044] For example, the molar equivalent ratio of the first isocyanate to the first hydroxyl-containing acrylate is 2:1, 3:1 or 4:1 (preferably 3:1), and the mass of the first catalyst accounts for 0.01%, 0.02% or 0.03% of the total mass; preferably, the mass of the first catalyst accounts for 0.02% of the total mass.

[0045] In one embodiment, the first isocyanate is a trifunctional isocyanate, and its structure contains three first isocyanate groups.

[0046] Preferably, the first isocyanate is hexamethylene diisocyanate trimer.

[0047] In one embodiment, the first hydroxyl-containing acrylate includes any one or more of first hydroxyethyl acrylate, first hydroxyethyl methacrylate, first hydroxypropyl acrylate, first hydroxypropyl methacrylate, and first hydroxybutyl acrylate.

[0048] Preferably, the first hydroxyl-containing acrylate is preferably 4-hydroxybutyl acrylate.

[0049] In one embodiment, the first catalyst includes any one or more of a first organic tin catalyst and a first organic bismuth catalyst.

[0050] Preferably, the catalyst is an organic bismuth catalyst.

[0051] In this embodiment, the monofunctional polyurethane acrylate (for example, low-viscosity monofunctional polyurethane acrylate) is obtained by reacting a second isocyanate, a monohydric alcohol, and a second hydroxyl-containing acrylate in the presence of a second catalyst and an inhibitor; wherein the molar ratio of the second isocyanate, the monohydric alcohol, and the second hydroxyl-containing acrylate is 0.08:0.5:0.5~1.15:1.5:1.5, and the content of the second catalyst and the inhibitor each accounts for 0.01~0.03% of the total mass.

[0052] For example, the molar ratio of the second isocyanate, the monohydric alcohol and the second hydroxyl-containing acrylate is 0.08:0.5:0.5, 1.02:1:1 or 1.15:1.5:1.5 (preferably 1.02:1:1), and the mass content of the second catalyst and the inhibitor each accounts for 0.01%, 0.02% or 0.03% of the total mass; preferably, the mass content of the second catalyst and the inhibitor each accounts for 0.02% of the total mass.

[0053] In one embodiment, the second isocyanate is a difunctional isocyanate, and its structure contains two second isocyanate groups.

[0054] Preferably, the second isocyanate is isophorone diisocyanate.

[0055] In one embodiment, the monohydric alcohol includes any one or more of methanol, ethanol, n-propanol and n-butanol.

[0056] Preferably, the monohydric alcohol is anhydrous ethanol.

[0057] In one embodiment, the second hydroxyl-containing acrylate includes any one or more of a second hydroxyethyl acrylate, a second hydroxyethyl methacrylate, a second hydroxypropyl acrylate, a second hydroxypropyl methacrylate, and a second hydroxybutyl acrylate.

[0058] Preferably, the hydroxyl-containing acrylate is preferably a second hydroxyethyl acrylate.

[0059] In one embodiment, the second catalyst includes any one or more of a second organic tin catalyst and a second organic bismuth catalyst.

[0060] Preferably, the catalyst is a second organic bismuth catalyst.

[0061] In this embodiment, the polymerization inhibitor includes any one or more of hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol and anthraquinone.

[0062] Preferably, the polymerization inhibitor is hydroquinone.

[0063] In this embodiment, the free radical photoinitiator includes any one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-isopropylthioxanthone, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone and benzoin dimethyl ether.

[0064] Preferably, the free radical photoinitiator is 1-hydroxy-cyclohexyl-phenyl ketone.

[0065] In this embodiment, the auxiliary agent includes a leveling agent, a coupling agent and a filler.

[0066] Specifically, the mass fraction of the leveling agent is 0-1 parts, the mass fraction of the coupling agent is 0-5 parts, and the mass fraction of the filler is 0-5 parts; wherein each component is not 0 parts.

[0067] Preferably, the leveling agent is an organic silicon leveling agent, preferably a polyether-modified polydimethylsiloxane copolymer.

[0068] Preferably, the coupling agent is a silane coupling agent, preferably γ-glycidoxypropyltrimethoxysilane.

[0069] Preferably, the filler is hydrophobic fumed silica.

[0070] As a preferred embodiment, the monomer-free UV-moisture dual-cure adhesive is composed of 40 to 70 parts of UV-moisture dual-cure resin, 10 to 35 parts of monofunctional polyurethane acrylate (i.e., low-viscosity monofunctional polyurethane acrylate), 2 to 4 parts of free radical photoinitiator, 0.1 to 0.5 parts of leveling agent, 0.1 to 2 parts of coupling agent and 1 to 2 parts of filler, by weight (or mass).

[0071] In a specific embodiment, the monomer-free UV-moisture dual-curing adhesive of this embodiment can be dual-cured by ultraviolet light and moisture. For example, during the initial curing by ultraviolet light, the wavelength of the light source is 365nm and the energy range is 2000-5000mJ / cm 2 ; When curing after moisture, the curing conditions are 40-60% RH & 20-30°C, 3-5 days.

[0072] In addition, this embodiment also provides a method for preparing a monomer-free UV-moisture dual-curing adhesive. The method for preparing the monomer-free UV-moisture dual-curing adhesive as described above specifically includes the following steps:

[0073] S1. Weigh the components of the formula content;

[0074] S2, mixing the UV-moisture dual-curing resin and the monofunctional polyurethane acrylate and stirring them evenly;

[0075] S3, adding free radical photoinitiator and dispersing it evenly;

[0076] S4, adding an auxiliary agent, mixing and stirring at room temperature to obtain the monomer-free UV-moisture dual-curing adhesive.

[0077] In this embodiment, a self-made UV-moisture dual-curing resin is used as the main resin, and a self-made monofunctional polyurethane acrylate (i.e., a low-viscosity monofunctional polyurethane acrylate) is used as a diluent. The prepared adhesive has low viscosity, low volatility, low sensitization, low shrinkage, aging resistance, and good adhesion to a variety of substrates. The monomer-free UV-moisture dual-curing adhesive of this embodiment does not introduce monomers and reactive diluents in the formula, but uses a self-made low-viscosity monofunctional polyurethane acrylate, which not only reduces viscosity and increases bonding strength and toughness, but also reduces the risk of sensitization.

[0078] In this embodiment, the UV-moisture dual-curing resin is prepared in the following manner:

[0079] S101, adding a certain amount of a first isocyanate and a dehydrated first hydroxyl-containing acrylate into a first designated container;

[0080] S102, start stirring, raise the temperature to 60-80°C, and react for 0.4-0.6h;

[0081] S103, adding the first catalyst, maintaining the temperature at 70-80° C., and continuing the reaction for 1-2 h (preferably, reacting at 75° C. for 2 h);

[0082] S104, measuring the NCO content in the system, and when the NCO content in the system reaches a first predetermined value, the material can be cooled and discharged to obtain the desired UV-moisture dual-curing resin.

[0083] The first predetermined value may be set according to actual conditions and may be a theoretical value.

[0084] In a specific example, the first designated container can be a four-necked split flask. Specifically, take a four-necked split flask, add 768.6g of hexamethylene diisocyanate trimer and 201.84g of dehydrated 4-hydroxybutyl acrylate, and react at 70°C for 0.5h. Add 0.2g of the first organic bismuth catalyst, and react at 75°C for 2h. When the NCO content in the system is less than 12%, cool to room temperature and discharge.

[0085] In this embodiment, the monofunctional polyurethane acrylate is prepared in the following manner:

[0086] S201, adding a certain amount of the second isocyanate and the second catalyst into a second designated container, and starting stirring;

[0087] S202, add anhydrous monohydric alcohol, raise the temperature to 60-80°C, and react for 0.4-0.6h;

[0088] S203, adding the dehydrated second hydroxyl-containing acrylate and the polymerization inhibitor, maintaining the temperature at 60-70° C., and continuing the reaction for 1-2 hours (preferably, reacting at 65° C. for 2 hours);

[0089] S204, measuring the NCO content in the system, and when the NCO content in the system reaches a second predetermined value, the system is cooled to room temperature and the desired monofunctional polyurethane acrylate is obtained.

[0090] The second predetermined value may be set according to actual conditions and may be a theoretical value.

[0091] In a specific example, the second designated container can be a four-necked split flask. Specifically, take a four-necked split flask, add 566.82g of isophorone diisocyanate, 0.2g of the second organic bismuth catalyst and 115.18g of anhydrous ethanol, and react at 60°C for 0.5h. Add 290.3g of the second dehydrated hydroxyethyl acrylate and 0.2g of hydroquinone, and react at 65°C for 2h. When the NCO content in the system is less than 0.1%, cool to room temperature and discharge.

[0092] In a specific embodiment, in this embodiment, three groups of experimental comparison tests are performed in Experimental Examples 1-6 and Comparative Examples 1-3 to test the product properties.

[0093] Sensitization test: According to GB / T 16886.10-2017 Biological Evaluation of Medical Devices Part 10: Irritation and Skin Sensitization Test, Level 0 means no allergic reaction, and Levels 1-3 correspond to mild to severe sensitization, respectively.

[0094] Adhesive strength & universal bonding test: The adhesive properties of each group of monomer-free UV-moisture dual-curing adhesives were compared, and the tensile shear properties of adhesives bonded to different substrates were tested using a microcomputer-controlled electronic universal testing machine (model: CMT4304, MTS) according to GB / T7124-2008 (Determination of tensile shear strength of adhesives). Tensile shear strength greater than or equal to 8Mpa was rated as √; tensile shear strength less than 8Mpa but greater than or equal to 4Mpa was rated as ○; tensile shear strength less than 4Mpa was rated as ×.

[0095] Aging resistance test: The aging resistance of each group of monomer-free UV-moisture dual-curing adhesives was compared, and the DAGE4000 thrust machine (model: 4000PXY, Nordson) was used to test the adhesive bonding between glass and PC substrate. After 48 hours in an 85℃ / 85%RH environment, the thrust force value change. Thrust greater than or equal to 10Kg was rated as √; thrust less than 10Kg but greater than or equal to 5Kg was rated as ○; thrust less than 5Kg was rated as ×.

[0096] In this embodiment, the details of the components used in the experimental examples and comparative examples are as follows:

[0097] A. Main resin: UV-moisture dual-curing resin (self-made in Example 1, Shanghai Hansi Industrial Co., Ltd.);

[0098] B. Diluent: low viscosity monofunctional polyurethane acrylate (self-made product in Example 2, Shanghai Hansi Industrial Co., Ltd.);

[0099] C. Free radical photoinitiator: 1-hydroxy-cyclohexyl-phenyl ketone (Omnirad 184D, IGM);

[0100] D. Leveling agent: Polyether Modified Polydimethylsiloxane Copolymers (BYK-333, Dalian Liansheng Trading Co., Ltd.);

[0101] E. Coupling agent: γ-glycidoxypropyltrimethoxysilane (LT-560, Hubei New Blue Sky New Materials Co., Ltd.);

[0102] F. Fumed silica: hydrophobic fumed silica (TS-720, Cabot Chemical Co., Ltd.).

[0103] The preparation method of each group of adhesives in the experimental examples and comparative examples is:

[0104] Component A and component B were conventionally stirred and mixed for 45 minutes in the absence of a solvent according to the amounts (unit: parts by weight) listed in Table 1, and then component C was added to the mixture. The mixture was stirred and mixed until component C was completely dissolved (about 20 minutes), and then component D and component E were added and stirred and mixed for 10 minutes. Finally, component F was added, and the mixture was stirred and mixed at room temperature for 15 minutes, and then vacuum stirred for 5 minutes to prepare the monomer-free UV-moisture dual-curing adhesives in Experimental Examples 1-6 and Comparative Examples 1-3.

[0105] Table 1: Experimental and comparative examples

[0106] A B C D E F Experimental Example 1 75 15 3 0.2 1 1.5 Experimental Example 2 70 20 3 0.2 1 1.5 Experimental Example 3 65 25 3 0.2 1 1.5 Experimental Example 4 65 20 2.8 0.2 1 1.5 Experimental Example 5 60 25 2.8 0.2 1 1.5 Experimental Example 6 60 30 3 0.2 1 1.5 Comparative Example 1 65 25 / 0.2 1 1.5 Comparative Example 2 65* 25 3 0.2 1 1.5 Comparative Example 3 65 25* 3 0.2 1 1.5

[0107] It should be noted that in Comparative Example 1, an adhesive was prepared in the absence of a photoinitiator.

[0108] In Comparative Example 2, the UV-moisture dual-curing resin was replaced with a pure light-curing polyurethane acrylate resin (Lucure 8674, Guangzhou Runao Chemical Materials Co., Ltd.).

[0109] In Comparative Example 3, the low-viscosity monofunctional polyurethane acrylate was replaced with isobornyl acrylate (IBOA, Changxing Chemical Industry Co., Ltd.).

[0110] Table 2: Performance test of experimental examples and comparative examples

[0111]

[0112] The experimental results are shown in Table 2. The monomer-free UV-moisture dual-curing adhesive prepared in the experimental example, after UV-moisture dual curing, showed excellent performance, with low viscosity, low volatility, low sensitization, low shrinkage, aging resistance and good bonding to a variety of substrates.

[0113] In Comparative Example 1, no photoinitiator was added, and pure moisture curing was adopted, which had a greater impact on the bonding strength of the substrate, and the aging resistance of the cured product was poor; in Comparative Example 2, after the UV-moisture dual-curing resin was replaced with a pure light-curing polyurethane acrylate resin, the entire glue system was a light-curing system, which had poor aging resistance and was slightly allergenic to human skin; in Comparative Example 3, after the low-viscosity monofunctional polyurethane acrylate was replaced with isobornyl acrylate, it was severely allergenic to human skin.

[0114] In summary, the monomer-free UV-moisture dual-curing adhesive and the preparation method thereof proposed in the present invention have the following advantages:

[0115] By using UV-moisture dual-cure resin as the main resin and homemade monofunctional polyurethane acrylate (i.e., low-viscosity monofunctional polyurethane acrylate) as the diluent, the prepared monomer-free UV-moisture dual-cure adhesive has low viscosity, low volatility, low sensitization, low shrinkage, aging resistance, and good adhesion to a variety of substrates. Since the monomer-free UV-moisture dual-cure adhesive of the present invention does not introduce monomers and reactive diluents into the formula, but uses homemade monofunctional polyurethane acrylate, while achieving the purpose of reducing viscosity and increasing bonding strength and toughness, it also reduces the risk of sensitization. The monomer-free UV-moisture dual-cure adhesive of the present invention is suitable for wearable electronic devices and handheld electronic devices that are in long-term contact with human skin.

[0116] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A monomer-free UV-moisture dual-curing adhesive, characterized in that: include: UV-moisture dual-cure resin, monofunctional polyurethane acrylate, free radical photoinitiator and additives; The mass fraction of the UV-moisture dual-curing resin is 20 to 80 parts; The mass fraction of the monofunctional polyurethane acrylate is 0 to 40 parts; the mass fraction of the free radical photoinitiator is 0 to 5 parts; the mass fraction of the auxiliary agent is 0 to 11 parts; wherein each component is not 0 parts.

2. The monomer-free UV-moisture dual-curing adhesive according to claim 1, characterized in that: The UV-moisture dual-curing resin is obtained by reacting a first isocyanate with a first hydroxyl-containing acrylate in the presence of a first catalyst; wherein the molar equivalent ratio of the first isocyanate to the first hydroxyl-containing acrylate is 2:1 to 4:1, and the mass of the first catalyst accounts for 0.01 to 0.03% of the total mass.

3. The monomer-free UV-moisture dual-curing adhesive according to claim 2, characterized in that: The first isocyanate is a trifunctional isocyanate, and contains three first isocyanate groups in its structure.

4. The monomer-free UV-moisture dual-curing adhesive according to claim 2, characterized in that: The first hydroxyl-containing acrylate includes any one or more of first hydroxyethyl acrylate, first hydroxyethyl methacrylate, first hydroxypropyl acrylate, first hydroxypropyl methacrylate and first hydroxybutyl acrylate.

5. The monomer-free UV-moisture dual-curing adhesive according to claim 2, characterized in that: The first catalyst includes any one or more of a first organic tin catalyst and a first organic bismuth catalyst.

6. The monomer-free UV-moisture dual-curing adhesive according to claim 1, characterized in that: The monofunctional polyurethane acrylate is obtained by reacting a second isocyanate, a monohydric alcohol, and a second hydroxyl-containing acrylate in the presence of a second catalyst and an inhibitor; wherein the molar ratio of the second isocyanate, the monohydric alcohol, and the second hydroxyl-containing acrylate is 0.08:0.5:0.5-1.15:1.5:1.5, and the content of the second catalyst and the inhibitor each accounts for 0.01-0.03% of the total mass.

7. The monomer-free UV-moisture dual-curing adhesive according to claim 6, characterized in that: The second isocyanate is a difunctional isocyanate, and contains two second isocyanate groups in its structure.

8. The monomer-free UV-moisture dual-curing adhesive according to claim 6, characterized in that: The monohydric alcohol includes any one or more of methanol, ethanol, n-propanol and n-butanol.

9. The monomer-free UV-moisture dual-curing adhesive according to claim 6, characterized in that: The second hydroxyl-containing acrylate includes any one or more of second hydroxyethyl acrylate, second hydroxyethyl methacrylate, second hydroxypropyl acrylate, second hydroxypropyl methacrylate and second hydroxybutyl acrylate.

10. The monomer-free UV-moisture dual-curing adhesive according to claim 6, characterized in that: The second catalyst includes any one or more of a second organic tin catalyst and a second organic bismuth catalyst.

11. The monomer-free UV-moisture dual-curing adhesive according to claim 6, characterized in that: The polymerization inhibitor includes any one or more of hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol and anthraquinone.

12. The monomer-free UV-moisture dual-curing adhesive according to claim 1, characterized in that: The free radical photoinitiator includes any one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-isopropylthioxanthone, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone and benzoin dimethyl ether.

13. The monomer-free UV-moisture dual-curing adhesive according to claim 1, characterized in that: The auxiliary agents include leveling agents, coupling agents and fillers; The mass fraction of the leveling agent is 0-1 parts, the mass fraction of the coupling agent is 0-5 parts, and the mass fraction of the filler is 0-5 parts; wherein each component is not 0 parts.

14. A method for preparing a monomer-free UV-moisture dual-curing adhesive, comprising preparing the monomer-free UV-moisture dual-curing adhesive as claimed in any one of claims 1 to 13, characterized in that: The details include: Weigh the ingredients of the formula content; Mix the UV-moisture dual-curing resin and the monofunctional polyurethane acrylate and stir well; Add free radical photoinitiator and disperse evenly; Add the auxiliary agent, mix and stir evenly at room temperature to obtain the monomer-free UV-moisture dual-curing adhesive.

15. The method for preparing a monomer-free UV-moisture dual-curing adhesive according to claim 14, characterized in that: The UV-moisture dual-curing resin is prepared in the following manner: Add the first isocyanate and the dehydrated first hydroxyl-containing acrylate into a first designated container; Start stirring, raise the temperature to 60-80°C, and react for 0.4-0.6h; Add the first catalyst, maintain the temperature at 70-80°C, and react for 1-2 hours; The NCO content in the system is measured, and when the NCO content in the system reaches a first predetermined value, the material is discharged at a lower temperature to obtain the desired UV-moisture dual-curing resin.

16. The method for preparing a monomer-free UV-moisture dual-curing adhesive according to claim 14, characterized in that: The monofunctional polyurethane acrylate is prepared in the following manner: Take the second isocyanate and the second catalyst and add them into the second designated container, and start stirring; Add anhydrous monohydric alcohol, raise the temperature to 60-80°C, and react for 0.4-0.6h; Add the dehydrated second hydroxyl-containing acrylate and the polymerization inhibitor, maintain the temperature at 60-70° C., and react for 1-2 hours; The NCO content in the system is measured, and when the NCO content in the system reaches a second predetermined value, the temperature is reduced to room temperature and the material is discharged to obtain the desired monofunctional polyurethane acrylate.

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