Photo-thermal dual-curing adhesive taking oxetane modified epoxy resin as matrix resin and preparation method of photo-thermal dual-curing adhesive

Abstract

The invention discloses a photo-thermal dual-curing adhesive taking oxetane modified epoxy resin as matrix resin and a preparation method of the photo-thermal dual-curing adhesive, and belongs to the field of adhesives. The problems that in the prior art, oxetane serves as photocuring matrix resin, epoxy resin serves as thermocuring matrix resin, thermocuring is incomplete, the curing efficiency is low, and compounding of a photoinitiator and a thermocuring agent influences the bonding strength and the shrinkage rate of a whole system are solved. The photo-thermal dual-curing adhesive is prepared from oxetane modified epoxy resin, oxetane, a reactive diluent, a free radical initiator, a cationic photoinitiator, a photosensitizer, an anhydride thermal curing agent and an imidazole thermal curing agent. The preparation method comprises the following steps: 1, synthesizing the oxetane modified epoxy resin; 2, weighing; and 3, mixing. The invention is used for the photo-thermal dual-curing adhesive taking the oxetane modified epoxy resin as the matrix resin and the preparation method of the photo-thermal dual-curing adhesive.

Description

Technical Field

[0001] The invention belongs to the field of adhesives. Background Art

[0002] Photothermal dual-curing adhesive is an adhesive that combines the advantages of photocuring and thermal curing. A few seconds of ultraviolet (UV) light can give the adhesive a high initial adhesion, and then thermal curing is performed. On the one hand, it cures the areas that are not exposed to UV light, and on the other hand, it further strengthens the bonding strength. Therefore, the heat generated by UV light irradiation and the heat generated by the UV cross-linking reaction are simultaneously used to initiate thermal curing in the adhesive system, making up for the shortcomings of light curing or thermal curing alone, thereby achieving the purpose of rapid and complete curing.

[0003] Existing photothermal dual curing generally uses epoxy acrylate as a photocurable oligomer and epoxy resin as a thermal curable oligomer. Although its photocuring time is fast, its shrinkage rate is large. Oxetane is a type of four-membered oxygen heterocyclic compound. Its molecular structure is characterized by a four-membered ring containing an oxygen atom. It is a new type of cationic polymerization monomer. Compared with traditional epoxy acrylate, oxetane has a smaller ring tension and a more stable chemical structure. The reactivity of oxetane is lower than that of the epoxy group, but because of its longer molecular chain, the volume shrinkage rate after curing is smaller and the adhesion performance is better. Therefore, oxetane can be used as an oligomer of photocurable resin to replace epoxy acrylate, thereby reducing the impact of shrinkage rate during photocuring setting. However, after oxetane is directly compounded and blended with epoxy resin, although the photocuring can be well set and the shrinkage rate of the photocured part can be reduced, it cannot reach the existing photothermal curing depth and the thermal curing effect is not good. In addition, the performance of the photothermal system based on oxetane is affected by the combination of photoinitiator and thermal curing agent. Therefore, it is very important to invent a photothermal dual-curing adhesive with oxetane-modified epoxy as the main resin and a suitable photoinitiator and thermal curing agent. Summary of the invention

[0004] The present invention aims to solve the problems of incomplete thermal curing and low curing efficiency in the existing adhesive with oxetane as the main photocuring resin and epoxy resin as the main thermal curing resin, and the influence of the combination of photoinitiator and thermal curing agent on the bonding strength and shrinkage rate of the whole system, and further provide a photothermal dual-curing adhesive with oxetane-modified epoxy resin as the main resin and a preparation method thereof.

[0005] A photothermal dual-curing adhesive with oxetane-modified epoxy resin as the main resin is prepared by 50 to 80 parts of oxetane-modified epoxy resin, 1 to 20 parts of oxetane, 1 to 20 parts of reactive diluent, 0.1 to 5 parts of free radical initiator, 0.1 to 5 parts of cationic photoinitiator, 0.1 to 5 parts of photosensitizer, 1 to 19 parts of acid anhydride thermal curing agent and 1 to 19 parts of imidazole thermal curing agent in parts by mass;

[0006] The oxetane-modified epoxy resin is obtained by modifying the epoxy resin with the modifier oxetane monomer; the modifier oxetane monomer is one of 2-chloromethyloxetane, 3-chloromethyl-3-methyloxetane, 3-chloromethyl-3-hydroxymethyl-1-oxetane and 3-chlorooxetane, or a combination of several thereof;

[0007] The oxetane is

[0008] One or a combination of several of them.

[0009] A method for preparing a light-heat dual-curing adhesive with oxetane-modified epoxy resin as the main resin is carried out according to the following steps:

[0010] 1. Synthesis of oxetane-modified epoxy resin:

[0011] The epoxy resin, the modifier oxetane monomer, potassium tert-butoxide and dimethylformamide are stirred evenly, and then reacted at a temperature of 80° C. to 90° C. for 2 h to 4 h, poured out while hot, and stored away from light to obtain an oxetane-modified epoxy resin;

[0012] The molar ratio of the epoxy resin to the modifier oxetane monomer is 1:(1-1.6); the potassium tert-butoxide is 1%-5% of the total mass of the epoxy resin and the modifier oxetane monomer; the mass ratio of the total mass of the epoxy resin and the modifier oxetane monomer to dimethylformamide is 1:(50-90);

[0013] 2. Weighing:

[0014] Weigh 50 to 80 parts of oxetane-modified epoxy resin, 1 to 20 parts of oxetane, 1 to 20 parts of reactive diluent, 0.1 to 5 parts of free radical initiator, 0.1 to 5 parts of cationic photoinitiator, 0.1 to 5 parts of photosensitizer, 1 to 19 parts of anhydride thermal curing agent and 1 to 19 parts of imidazole thermal curing agent according to mass proportion;

[0015] 3. Mixing:

[0016] Under the condition of avoiding light and keeping the temperature at 20°C to 30°C, the weighed oxetane-modified epoxy resin, oxetane and active diluent are mechanically stirred and mixed for 20min to 40min, and then the weighed free radical initiator, cationic photoinitiator, photosensitizer, acid anhydride thermal curing agent and imidazole thermal curing agent are added, and the mechanical stirring and mixing is continued for 20min to 40min under the condition of avoiding light and keeping the temperature at 20°C to 30°C, and the mixture is sealed and frozen in the dark to obtain a light-thermal dual-curing adhesive with oxetane-modified epoxy resin as the main resin.

[0017] The beneficial effects of the present invention are:

[0018] 1. The addition of oxetane-modified epoxy resin solves the problem of incomplete or even no curing after oxetane and epoxy resin are blended, while retaining the advantages of oxetane, such as fast photocuring rate, short photocuring time, low shrinkage rate and strong bonding strength. During the photocuring process, it can be quickly formed, reducing the impact of instantaneous high temperature on the shrinkage rate of the entire system; photocuring allows the curing of the cationic photoinitiator to be fully exerted, and then the oxetane-modified epoxy resin is thermally cured to prevent the temperature increase from affecting the dark reaction stage of photocuring, and at the same time avoid the strong proton acid formed when the cationic photoinitiator is triggered and the excessive oxetane of the alkaline thermal curing agent, which will cause acid-base neutralization reaction during the thermal curing process, thereby affecting the entire system.

[0019] 2. The content of cationic initiator in the subsequent compounding of initiators cannot be too high. The addition of free radical initiator not only supplements the problem of short wavelength of cationic initiator, but also broadens the wavelength range of photoinitiator, making the photocuring more thorough, reducing deformation and shrinkage during thermal curing. The addition of imidazole thermal curing agent can gel and cure in a short time at low temperature. However, imidazole curing agent is easy to cause yellowing during curing, making the cured product colored. And compared with other types of thermal curing agents, the shrinkage rate is high, so the addition of acid anhydride thermal curing agent at the same time improves the problem of slow curing speed of acid anhydride curing agent and reduces the shrinkage rate after thermal curing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the infrared spectrum of the oxetane-modified epoxy resin prepared in step 1 of Example 1. DETAILED DESCRIPTION

[0021] Specific implementation method 1: A light-heat dual-curing adhesive with oxetane-modified epoxy resin as the main resin of this implementation method is prepared by 50 to 80 parts of oxetane-modified epoxy resin, 1 to 20 parts of oxetane, 1 to 20 parts of active diluent, 0.1 to 5 parts of free radical initiator, 0.1 to 5 parts of cationic photoinitiator, 0.1 to 5 parts of photosensitizer, 1 to 19 parts of acid anhydride thermal curing agent and 1 to 19 parts of imidazole thermal curing agent in parts by mass;

[0022] The oxetane-modified epoxy resin is obtained by modifying the epoxy resin with the modifier oxetane monomer; the modifier oxetane monomer is one of 2-chloromethyloxetane, 3-chloromethyl-3-methyloxetane, 3-chloromethyl-3-hydroxymethyl-1-oxetane and 3-chlorooxetane, or a combination of several thereof;

[0023] The oxetane is

[0024] One or a combination of several of them.

[0025] The structural formula of the 2-chloromethyloxetane is:

[0026]

[0027] The structural formula of the 3-chloromethyl-3-methyloxetane is:

[0028]

[0029] The structural formula of the oxetane is 3-chloromethyl-3-hydroxymethyl-1-oxetane:

[0030]

[0031] The structural formula of the oxetane is 3-chlorooxetane:

[0032]

[0033] The beneficial effects of this specific implementation are:

[0034] 1. The addition of oxetane-modified epoxy resin solves the problem of incomplete or even no curing after oxetane and epoxy resin are blended, while retaining the advantages of oxetane, such as fast photocuring rate, short photocuring time, low shrinkage rate and strong bonding strength. During the photocuring process, it can be quickly formed, reducing the impact of instantaneous high temperature on the shrinkage rate of the entire system; photocuring allows the curing of the cationic photoinitiator to be fully exerted, and then the oxetane-modified epoxy resin is thermally cured to prevent the temperature increase from affecting the dark reaction stage of photocuring, and at the same time avoid the strong proton acid formed when the cationic photoinitiator is triggered and the excessive oxetane of the alkaline thermal curing agent, which will cause acid-base neutralization reaction during the thermal curing process, thereby affecting the entire system.

[0035] 2. The content of cationic initiator in the subsequent compounding of initiators cannot be too high. The addition of free radical initiator not only supplements the problem of short wavelength of cationic initiator, but also broadens the wavelength range of photoinitiator, making the photocuring more thorough, reducing deformation and shrinkage during thermal curing. The addition of imidazole thermal curing agent can gel and cure in a short time at low temperature. However, imidazole curing agent is easy to cause yellowing during curing, making the cured product colored. And compared with other types of thermal curing agents, the shrinkage rate is high, so the addition of acid anhydride thermal curing agent at the same time improves the problem of slow curing speed of acid anhydride curing agent and reduces the shrinkage rate after thermal curing.

[0036] Specific implementation method 2: This implementation method is different from the specific implementation method 1 in that the epoxy resin is bisphenol A type epoxy resin. The rest is the same as the specific implementation method 1.

[0037] Specific embodiment 3: This embodiment is different from specific embodiment 1 or 2 in that the active diluent is one or a combination of isobornyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, 1,4-butanediol diglycidyl ether and trimethylolpropane triacrylate. Others are the same as specific embodiment 1 or 2.

[0038] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the free radical initiator is one or a combination of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexyl phenyl ketone and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide. Others are the same as specific embodiments 1 to 3.

[0039] Specific embodiment 5: This embodiment is different from specific embodiments 1 to 4 in that the cationic photoinitiator is one or a combination of diphenyl-(4-phenylsulfonium)phenylsulfonium hexafluorophosphate, 4-isobutylphenyl-4'-tolyliodonium hexafluorophosphate, bis(4-tert-butylphenyl)iodonium hexafluorophosphate, mixed sulfonium hexafluorophosphate bis(4-(diphenylsulfonium)phenyl)sulfide-bishexafluorophosphate and isopropylphenylcyclopentadienyl iron hexafluorophosphate. Others are the same as specific embodiments 1 to 4.

[0040] The CAS number of the mixed sulfonium hexafluorophosphate bis(4-(diphenylsulfonium)phenyl)sulfide-bishexafluorophosphate is 75482-18-7.

[0041] Specific embodiment 6: This embodiment is different from specific embodiments 1 to 5 in that the photosensitizer is one or a combination of p-N,N-dimethylaminobenzoic acid ethyl ester, 2-isopropylthioxanthone and benzoin dimethyl ether. Other aspects are the same as specific embodiments 1 to 5.

[0042] Specific embodiment 7: This embodiment is different from specific embodiments 1 to 6 in that the acid anhydride thermal curing agent is one or a combination of phthalic anhydride, tetrahydrophthalic anhydride and methyl nadic anhydride. Other aspects are the same as specific embodiments 1 to 6.

[0043] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the imidazole thermal curing agent is one or a combination of 2-phenylimidazole, 2-methylimidazole and imidazole adduct PN23. Other aspects are the same as specific embodiments 1 to 7.

[0044] Specific embodiment 9: This embodiment is a method for preparing a light-heat dual-curing adhesive with oxetane-modified epoxy resin as the main resin, which is carried out according to the following steps:

[0045] 1. Synthesis of oxetane-modified epoxy resin:

[0046] The epoxy resin, the modifier oxetane monomer, potassium tert-butoxide and dimethylformamide are stirred evenly, and then reacted at a temperature of 80° C. to 90° C. for 2 h to 4 h, poured out while hot, and stored away from light to obtain an oxetane-modified epoxy resin;

[0047] The molar ratio of the epoxy resin to the modifier oxetane monomer is 1:(1-1.6); the potassium tert-butoxide is 1%-5% of the total mass of the epoxy resin and the modifier oxetane monomer; the mass ratio of the total mass of the epoxy resin and the modifier oxetane monomer to dimethylformamide is 1:(50-90);

[0048] 2. Weighing:

[0049] Weigh 50 to 80 parts of oxetane-modified epoxy resin, 1 to 20 parts of oxetane, 1 to 20 parts of reactive diluent, 0.1 to 5 parts of free radical initiator, 0.1 to 5 parts of cationic photoinitiator, 0.1 to 5 parts of photosensitizer, 1 to 19 parts of anhydride thermal curing agent and 1 to 19 parts of imidazole thermal curing agent according to mass proportion;

[0050] 3. Mixing:

[0051] Under the condition of avoiding light and keeping the temperature at 20°C to 30°C, the weighed oxetane-modified epoxy resin, oxetane and active diluent are mechanically stirred and mixed for 20min to 40min, and then the weighed free radical initiator, cationic photoinitiator, photosensitizer, acid anhydride thermal curing agent and imidazole thermal curing agent are added, and the mechanical stirring and mixing is continued for 20min to 40min under the condition of avoiding light and keeping the temperature at 20°C to 30°C, and the mixture is sealed and frozen in the dark to obtain a light-thermal dual-curing adhesive with oxetane-modified epoxy resin as the main resin.

[0052] This specific implementation method takes the introduction of 3-chlorooxetane as an example: 3-chlorooxetane is added to epoxy resin for reaction to generate oligomers of grafted oxetane, as follows:

[0053]

[0054] Specific embodiment 10: This embodiment differs from specific embodiment 9 in that the stirring speed of the mechanical stirring and mixing in step 3 is 200 r / min to 800 r / min; the frozen storage in step 3 is specifically frozen storage at a temperature of -18°C to 0°C. The rest is the same as specific embodiment 9.

[0055] The following examples are used to verify the beneficial effects of the present invention:

[0056] Embodiment 1:

[0057] A photothermal dual-curing adhesive with oxetane-modified epoxy resin as the main resin, which is prepared by weight from 60 parts of oxetane-modified epoxy resin, 20 parts of oxetane, 20 parts of reactive diluent, 4 parts of free radical initiator, 4 parts of cationic photoinitiator, 4 parts of photosensitizer, 10 parts of acid anhydride thermal curing agent and 10 parts of imidazole thermal curing agent;

[0058] The oxetane-modified epoxy resin is obtained by modifying the epoxy resin with the modifier oxetane monomer; the modifier oxetane monomer is 3-chlorooxetane;

[0059] The oxetane is

[0060] The epoxy resin is bisphenol A epoxy resin 830S.

[0061] The active diluent is isobornyl methacrylate.

[0062] The free radical initiator is diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide.

[0063] The cationic photoinitiator is initiator 261, namely cumyl cyclopentadienyl iron hexafluorophosphate.

[0064] The photosensitizer is 2-isopropylthioxanthone.

[0065] The acid anhydride thermal curing agent is methyl nadic anhydride.

[0066] The imidazole thermal curing agent is 2-methylimidazole.

[0067] The preparation method of the above-mentioned light-heat dual-curing adhesive with oxetane-modified epoxy resin as the main resin is carried out according to the following steps:

[0068] 1. Synthesis of oxetane-modified epoxy resin:

[0069] The epoxy resin, the modifier oxetane monomer, potassium tert-butoxide and dimethylformamide were stirred evenly, and then reacted at a temperature of 85° C. for 4 hours, poured out while hot, and stored away from light to obtain an oxetane-modified epoxy resin;

[0070] The molar ratio of the epoxy resin to the modifier oxetane monomer is 1:1.5; the potassium tert-butoxide is 3% of the total mass of the epoxy resin and the modifier oxetane monomer; the mass ratio of the total mass of the epoxy resin and the modifier oxetane monomer to dimethylformamide is 1:90;

[0071] 2. Weighing:

[0072] Weigh 60 parts of oxetane-modified epoxy resin, 20 parts of oxetane, 20 parts of reactive diluent, 4 parts of free radical initiator, 4 parts of cationic photoinitiator, 4 parts of photosensitizer, 10 parts of anhydride thermal curing agent and 10 parts of imidazole thermal curing agent according to mass proportion;

[0073] 3. Mixing:

[0074] Under the conditions of being protected from light, stirring at a speed of 600 r / min and a temperature of 20°C to 30°C, the weighed oxetane-modified epoxy resin, oxetane and reactive diluent are mechanically stirred and mixed for 40 minutes, and then the weighed free radical initiator, cationic photoinitiator, photosensitizer, acid anhydride thermal curing agent and imidazole thermal curing agent are added, and the mechanical stirring and mixing is continued for 40 minutes under the conditions of being protected from light, stirring at a speed of 600 r / min and a temperature of 20°C to 30°C, and the mixture is sealed and frozen for storage in a light-proof manner to obtain a light-thermal dual-curing adhesive with oxetane-modified epoxy resin as the main resin;

[0075] The frozen storage specifically refers to frozen storage at a temperature of -18°C while still maintaining a liquid state.

[0076] The light-heat dual-curing adhesive prepared in this embodiment with oxetane-modified epoxy resin as the main resin is easy to cure at room temperature and easy to cure when exposed to light, so it needs to be sealed and frozen for storage away from light.

[0077] Embodiment 2: This embodiment is different from Embodiment 1 in that the modifier oxetane monomer is 3-chloromethyl-3-methyloxetane. Others are the same as Embodiment 1.

[0078] Embodiment 3: This embodiment is different from Embodiment 1 in that the modifier oxetane monomer is 3-chloromethyl-3-hydroxymethyl-1-oxetane. Others are the same as Embodiment 1.

[0079] Embodiment 4: This embodiment is different from Embodiment 1 in that the cationic photoinitiator is bis(4-tert-butylphenyl)iodonium hexafluorophosphate. The rest is the same as Embodiment 1.

[0080] Embodiment 5: This embodiment is different from Embodiment 1 in that the free radical initiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone. The rest is the same as Embodiment 1.

[0081] Embodiment 6: This embodiment is different from Embodiment 1 in that: the acid anhydride heat curing agent is phthalic anhydride; the imidazole heat curing agent is imidazole adduct PN23. The rest is the same as Embodiment 1.

[0082] Embodiment 7: This embodiment is different from Embodiment 1 in that the cationic photoinitiator is 2 parts. The rest is the same as Embodiment 1.

[0083] Comparative Experiment 1: This comparative experiment is different from Example 1 in that the oxetane-modified epoxy resin is replaced with non-modified epoxy resin 830S. The rest is the same as Example 1.

[0084] Comparative Experiment 2: This comparative experiment is different from Example 1 in that the acid anhydride thermal curing agent is omitted and the imidazole thermal curing agent is 20 parts. The rest is the same as Example 1.

[0085] Comparative Experiment 3: This comparative experiment is different from Example 1 in that the imidazole type thermal curing agent is omitted, the acid anhydride type thermal curing agent is phthalic anhydride, and the acid anhydride type thermal curing agent is 20 parts. The rest is the same as Example 1.

[0086] Comparative Experiment 4: This comparative experiment differs from Example 1 in that the free radical initiator is omitted. Other aspects are the same as Example 1.

[0087] The following tests were performed on the light-heat dual-curing adhesives prepared in Examples 1 to 7 and Comparative Experiments 1 to 4:

[0088] 1. Storage stability of light-heat dual-curing adhesive: Compare the viscosity before and after storage at 50°C for three days, and calculate the viscosity growth rate in %.

[0089] 2. Curing time of photothermal dual-curing adhesive: The curing time of the coating is measured by finger-drying method. Apply photothermal dual-curing adhesive on a glass slide with a thickness of 100 μm and place it in a light curing machine. 2 Curing under the conditions of , press lightly with fingers from time to time, if there is no trace, it can be regarded as surface dry, and the time used is the surface dry curing time.

[0090] 3. Appearance of light and heat dual curing adhesive: visual inspection.

[0091] 4. UV transmittance of photothermal dual-curing adhesive before and after curing: measuring wavelength 365nm; curing process: the photothermal dual-curing adhesive is coated on a glass slide to a thickness of 100μm, and the film coated with the photothermal dual-curing adhesive is placed at a power of 220mw / cm 2 The film was cured in a UV curing instrument (365 nm) for 20 seconds and then heated at 100°C for 30 minutes.

[0092] 5. Curing depth of photothermal dual curing adhesive: Take 2mm as the benchmark to measure the curing depth after photothermal curing. Curing process: The photothermal dual curing adhesive is coated on a glass slide to a thickness of 2mm. The film coated with the photothermal dual curing adhesive is placed at a power of 220mw / cm 2 The film was cured in a UV curing instrument (365 nm) for 20 seconds and then heated at 100°C for 30 minutes.

[0093] 6. Glass transition temperature of the photothermal dual curing adhesive after curing (℃): static thermomechanical analysis method, thermal analysis instrument (model DMA, manufactured by TA company), heating rate: 5℃ / min, temperature range: -55℃ to 200℃. Curing process: The photothermal dual curing adhesive was coated on a glass slide to a thickness of 1mm, and the film coated with the photothermal dual curing adhesive was placed under a power of 220mw / cm 2 The film was cured in a UV curing instrument (365 nm) for 20 seconds and then heated at 100°C for 30 minutes.

[0094] 7. Volume shrinkage: Determine the density of the photothermal dual-curing adhesive before and after curing, and then calculate the shrinkage based on the density. Shrinkage = (ρ1-ρ2) / ρ1×100%; where ρ1 and ρ2 are the densities after and before curing, respectively. Curing process: The photothermal dual-curing adhesive is coated on a glass slide to a thickness of 1mm, and the film coated with the photothermal dual-curing adhesive is placed at a power of 220mw / cm 2 The film was cured in a UV curing instrument (365 nm) for 20 seconds and then heated at 100°C for 30 minutes.

[0095] 8. Water absorption of the photothermal dual curing adhesive after curing: 25°C, standing for 24 hours. Curing process: The photothermal dual curing adhesive is coated on a glass slide to a thickness of 1mm, and the film coated with the photothermal dual curing adhesive is placed at a power of 220mw / cm 2 The film was cured in a UV curing instrument (365 nm) for 20 seconds and then heated at 100°C for 30 minutes.

[0096] 9. Shear strength (MPa): Apply the light-heat dual-curing adhesive to the substrate to be bonded and perform light curing or light-heat curing; Light curing (substrate: glass, PC, PMMA): LED wavelength 365nm, 220mW / cm 2 , 20s; Photothermal curing (substrate: glass, PC, PMMA): LED wavelength 365nm, 220mW / cm 2 , 20s+100℃, 30min). Thermal curing (substrate: aluminum): 100℃, 30min; refer to GB / T7124-2008 shear strength.

[0097] The above test results are shown in Tables 1 to 3:

[0098] Table 1

[0099]

[0100]

[0101] Table 2

[0102] Comparative Experiment 1 Comparative Experiment 2 Comparative Experiment 3 Comparative Experiment 4 Storage stability (%) 1 4.5 Partially cured 5.5 Table curing time (s) 16 6 10 4 Appearance turbid turbid transparent transparent Transmittance before UV curing (%) 45.7 34.1 88.3 88.5 Transmittance after UV curing (%) 51.2 35.5 87.5 89.6 Depth of cure (%) 100 88 70 90 Glass transition temperature(℃) 100 25 34 55 Volume shrinkage (%) Incomplete curing 4.2 3.7 5.1 Water absorption (%) - 4.7 5.3 6.5

[0103] Table 3 Photothermal curing shear data (MPa)

[0104]

[0105]

[0106] It can be seen from the results of Examples 1 to 7 and Comparative Experiments 1 to 4 that the compounding of epoxy resin modified with oxetane and photocurable oxetane solves the problem of incomplete thermal curing when oxetane is thermally cured alone after being blended with epoxy resin. The photocuring is rapid, and the shrinkage rate is reduced during further thermal curing. The addition of free radical initiators supplements the wavelength range of cationic photoinitiators, and can continue to initiate polymerization after the light stops, so that thick coatings and areas that are difficult to irradiate are fully cured, improving the curing efficiency; the active ingredients are then heated and further thermally cured to achieve rapid and high-strength curing, with strong bonding strength while maintaining good storage stability.

[0107] Figure 1 This is the infrared spectrum of the oxetane-modified epoxy resin prepared in step 1 of Example 1. As can be seen from the figure, 2964cm -1 、2866cm -1 、1478cm -1 The corresponding absorption peak of CH in methyl group; 2933cm -1 The corresponding absorption peak of CH in methylene is 982cm -1 and 828cm -1 The absorption peak corresponding to the four-membered oxygen heterocycle can be observed at 3410cm -1 The peak value of the characteristic absorption peak of the hydroxyl group becomes smaller, proving that the oxetane-modified epoxy resin is successfully synthesized.

Claims

1. A light-heat dual-curing adhesive with oxetane-modified epoxy resin as the main resin, characterized in that It is prepared from 50 to 80 parts of oxetane-modified epoxy resin, 1 to 20 parts of oxetane, 1 to 20 parts of active diluent, 0.1 to 5 parts of free radical initiator, 0.1 to 5 parts of cationic photoinitiator, 0.1 to 5 parts of photosensitizer, 1 to 19 parts of acid anhydride thermal curing agent and 1 to 19 parts of imidazole thermal curing agent in parts by mass. The oxetane-modified epoxy resin is obtained by modifying the epoxy resin with the modifier oxetane monomer; the modifier oxetane monomer is one of 2-chloromethyloxetane, 3-chloromethyl-3-methyloxetane, 3-chloromethyl-3-hydroxymethyl-1-oxetane and 3-chlorooxetane, or a combination of several thereof; The oxetane is One or a combination of several of them.

2. The photothermal dual curing adhesive with oxetane-modified epoxy resin as the main resin according to claim 1, characterized in that The epoxy resin is bisphenol A type epoxy resin.

3. The photothermal dual curing adhesive with oxetane-modified epoxy resin as the main resin according to claim 1, characterized in that The active diluent is one of isobornyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, 1,4-butanediol diglycidyl ether and trimethylolpropane triacrylate or a combination of several thereof.

4. The photothermal dual curing adhesive with oxetane-modified epoxy resin as the main resin according to claim 1, characterized in that The free radical initiator is one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexyl phenyl ketone and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide or a combination of several thereof.

5. The photothermal dual curing adhesive with oxetane-modified epoxy resin as the main resin according to claim 1, characterized in that The cationic photoinitiator is one of diphenyl-(4-phenylsulfonium)phenylsulfonium hexafluorophosphate, 4-isobutylphenyl-4'-tolyl iodine hexafluorophosphate, bis(4-tert-butylphenyl)iodonium hexafluorophosphate, mixed sulfonium hexafluorophosphate bis(4-(diphenylsulfonium)phenyl)sulfide-bishexafluorophosphate and isopropyl cyclopentadienyl iron hexafluorophosphate, or a combination of several thereof.

6. The photothermal dual curing adhesive with oxetane-modified epoxy resin as the main resin according to claim 1, characterized in that The photosensitizer is one of ethyl p-N, N-dimethylaminobenzoate, 2-isopropylthioxanthone and benzoin dimethyl ether or a combination of several of them.

7. The photothermal dual curing adhesive with oxetane-modified epoxy resin as the main resin according to claim 1, characterized in that The acid anhydride heat curing agent is one of phthalic anhydride, tetrahydrophthalic anhydride and methyl nadic anhydride or a combination of several of them.

8. The photothermal dual curing adhesive with oxetane-modified epoxy resin as the main resin according to claim 1, characterized in that The imidazole thermal curing agent is one of 2-phenylimidazole, 2-methylimidazole and imidazole adduct PN23 or a combination of several of them.

9. The method for preparing a photothermal dual curing adhesive with oxetane-modified epoxy resin as the main resin as claimed in claim 1, characterized in that It is carried out in the following steps:

1. Synthesis of oxetane-modified epoxy resin: The epoxy resin, the modifier oxetane monomer, potassium tert-butoxide and dimethylformamide are stirred evenly, and then reacted at a temperature of 80° C. to 90° C. for 2 h to 4 h, poured out while hot, and stored away from light to obtain an oxetane-modified epoxy resin; The molar ratio of the epoxy resin to the modifier oxetane monomer is 1:(1-1.6); the potassium tert-butoxide is 1%-5% of the total mass of the epoxy resin and the modifier oxetane monomer; the mass ratio of the total mass of the epoxy resin and the modifier oxetane monomer to dimethylformamide is 1:(50-90); 2. Weighing: Weigh 50 to 80 parts of oxetane-modified epoxy resin, 1 to 20 parts of oxetane, 1 to 20 parts of reactive diluent, 0.1 to 5 parts of free radical initiator, 0.1 to 5 parts of cationic photoinitiator, 0.1 to 5 parts of photosensitizer, 1 to 19 parts of anhydride thermal curing agent and 1 to 19 parts of imidazole thermal curing agent according to mass proportion; 3. Mixing: Under the condition of avoiding light and keeping the temperature at 20°C to 30°C, the weighed oxetane-modified epoxy resin, oxetane and active diluent are mechanically stirred and mixed for 20min to 40min, and then the weighed free radical initiator, cationic photoinitiator, photosensitizer, acid anhydride thermal curing agent and imidazole thermal curing agent are added, and the mechanical stirring and mixing is continued for 20min to 40min under the condition of avoiding light and keeping the temperature at 20°C to 30°C, and the mixture is sealed and frozen in the dark to obtain a light-thermal dual-curing adhesive with oxetane-modified epoxy resin as the main resin.

10. The method for preparing a light-heat dual-curing adhesive with oxetane-modified epoxy resin as the main resin according to claim 9, characterized in that The stirring speed of the mechanical stirring mixing described in step three is 200r / min to 800r / min; the frozen storage described in step three is specifically frozen storage at a temperature of -18°C to 0°C.

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