Spiro expansion monomer, preparation method thereof and resin composition

Abstract

The invention provides a spirocyclic expansion monomer, a preparation method thereof and a resin composition. The structural formula of the spirocyclic expansion monomer is as shown in formula I in the specification. The spiro expansion monomer has the advantages of high reaction activity, low shrinkage rate, good compatibility and the like, and the curing volume shrinkage rate of epoxy resin can be reduced through the ring opening effect of the spiro monomer after the spiro expansion monomer is added into an epoxy resin system, so that the curing shrinkage stress is reduced. The invention also provides a resin composition. The resin composition comprises epoxy resin and the spiro-expansive monomer and / or the oligomer of the spiro-expansive monomer. The spiro expansion monomer is applied to an epoxy resin system to prepare a precise fixing adhesive, the shrinkage rate of the adhesive in the curing process can be effectively reduced, so that the curing shrinkage stress is reduced, the coupling precision is improved, and the spiro expansion monomer is mainly applied to the fields of electronic component bonding, optical device bonding and fixing and the like.

Description

Technical Field

[0001] This application relates to the field of epoxy resin technology, and more specifically, to spirocyclic expanded monomers and their preparation methods, and resin compositions. Background Technology

[0002] The curing shrinkage rate of epoxy resin varies depending on the curing agent and curing system, and is generally between 3% and 7%. In order to reduce the curing shrinkage rate, previous studies have mainly focused on three paths: a) adding expanding monomers or prepolymers to compensate for the volume shrinkage caused by the transformation of the van der Waals forces during curing to covalent bonds through the volume expansion of their ring opening; b) using the concept of prepolymers / polymers such as hyperbranched structures to achieve low volume shrinkage by changing the interaction force / distance between them and epoxy monomers / crosslinking networks before and after curing; (3) using the principle of phase separation to compensate for the volume shrinkage of epoxy curing by transforming the high density of the miscible system before curing to the low density caused by phase separation during curing. However, the modifiers generally used are mainly high-performance high molecular weight thermoplastic resins, which lead to a significant increase in the viscosity of the modified epoxy system, thus limiting their use in adhesive systems.

[0003] Currently, in precision fixing scenarios, the shrinkage stress during the curing process of epoxy resin adhesives can lead to positional accuracy deviations and surface shape changes. Therefore, epoxy resins still need to further reduce their curing shrinkage rate to expand their application range, especially in the fixing of precision electronic components. Summary of the Invention

[0004] This application discloses a spirocyclic expanding monomer and its preparation method, as well as a resin composition. The spirocyclic expanding monomer in this application has the advantages of high reactivity, low shrinkage rate, and good compatibility. When added to an epoxy resin system, it can reduce the curing volume shrinkage rate of the epoxy resin through the ring-opening effect of the spirocyclic monomer, thereby reducing the curing shrinkage stress.

[0005] In a first aspect, this application provides a spiral toroidal expanded monomer, the structural formula of which is shown in Formula I;

[0006]

[0007] This application also provides a method for preparing a spirocyclic expanded monomer, the method comprising the following steps:

[0008] Under stirring, a mixture containing bis(trimethylolpropane) and an organic solvent is refluxed and dehydrated. Then, an alkaline catalyst, tetraethyl orthocarbonate, and diethyl carbonate are added. The bis(trimethylolpropane) and tetraethyl orthocarbonate are first synthesized to obtain a spirocyclic intermediate. The spirocyclic intermediate and diethyl carbonate undergo a transesterification reaction to obtain a spirocyclic expanded monomer.

[0009] In some embodiments, the organic solvent is selected from at least one of toluene, acetone, anhydrous ethanol, and ethyl acetate.

[0010] In some embodiments, the temperature of the reflux dehydration treatment is 100°C to 125°C, and the time of the reflux dehydration treatment is 2 hours to 4 hours.

[0011] In some embodiments, the alkaline catalyst is selected from at least one of potassium hydroxide and sodium hydroxide.

[0012] In some embodiments, the molar ratio of the bis(trimethylolpropane) to the ortho-tetraethyl carbonate and the diethyl carbonate is 1:(0.4-0.8):(1-1.5).

[0013] In some embodiments, the transesterification reaction is carried out at a temperature of 150°C to 180°C for a duration of 3 to 5 hours.

[0014] Secondly, this application provides a resin composition comprising an active component and an additive, wherein the active component comprises an epoxy resin and the aforementioned spirocyclic expanding monomer and / or oligomers of the spirocyclic expanding monomer.

[0015] In some embodiments, the weight ratio of the epoxy resin to the spirocyclic expanded monomer and / or the oligomer of the spirocyclic expanded monomer is (70-90):(10-30).

[0016] In some embodiments, the epoxy resin includes one or more of the following: aromatic ring epoxy resin, glycidyl ether epoxy resin, bisphenol A glycidyl ether epoxy resin, glycidyl ester epoxy resin, alicyclic epoxy resin, and hydrogenated bisphenol A epoxy resin.

[0017] In some embodiments, the epoxy resin is an alicyclic epoxy resin, wherein the epoxy equivalent in the alicyclic epoxy resin is 100 g / mol to 300 g / mol.

[0018] In some embodiments, the alicyclic epoxy resin includes one or a combination of at least two of the following: 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate, methyl 3,4-epoxycyclohexanecarboxylate, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, and 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylate).

[0019] In some embodiments, based on 100 wt% of the active component, the resin composition further includes 100 wt% to 150 wt% of filler, the filler including at least one of spherical silica powder, nano titanium dioxide, and calcium carbonate powder.

[0020] In some embodiments, the resin composition further comprises a curing agent of 10 wt% to 25 wt% by mass, based on 100 wt% of the active component, wherein the curing agent is methylhexahydrophthalic anhydride.

[0021] In some embodiments, the resin composition further comprises, based on 100 wt% of the active component, an initiator comprising 1 wt% to 5 wt% of the active component, wherein the initiator is a cationic initiator selected from at least one of hexafluoroantimonate and hexafluorophosphate.

[0022] In some embodiments, the resin composition is first pre-cured at 70°C for 1 to 2 hours, then cured at 110°C for 1 to 2 hours, and then cured at 150°C to 170°C for 1 to 2 hours. The volume shrinkage rate of the resin composition during the curing process is 0.1% to 0.6%.

[0023] This application also provides the use of the above-described resin composition in electronic devices.

[0024] Compared with existing technologies, the spirocyclic expanding monomer provided in this application has advantages such as high reactivity, low shrinkage, good compatibility, and low biotoxicity of the synthesis route. When added to an epoxy resin system, its ring-opening action reduces the curing volume shrinkage of the epoxy resin, thereby reducing curing shrinkage stress. The spirocyclic expanding monomer of this application, when used in epoxy resin systems to prepare precision adhesives, can effectively reduce the shrinkage rate of the adhesive during curing, thereby reducing curing shrinkage stress and improving coupling accuracy. It is mainly used in the bonding and fixing of electronic components and optical devices. Attached Figure Description

[0025] Figure 1 The 1H NMR spectrum of the spirocyclic expanded monomer provided in the embodiments of this application.

[0026] Figure 2 Fourier transform infrared spectrum of the spirocyclic expanded monomer provided in the embodiments of this application.

[0027] Figure 3 The gel permeation chromatogram of the spirocyclic expanded monomer provided in the embodiments of this application is shown. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Epoxy resins are widely used as structural adhesives to bond metals and plastics. However, during the curing process, epoxy resins inevitably undergo volume shrinkage, generating shrinkage stress, which becomes a potential destructive factor. This can lead to a sharp decrease in material strength, even causing cracking; or it can cause deterioration and parameter drift in electronic or optical components. However, regardless of the method used, volume shrinkage can only be reduced, not completely eliminated.

[0030] Currently, in precision fixing scenarios, the shrinkage stress during the curing process of epoxy resin adhesives can lead to positional accuracy deviations and surface shape changes. Therefore, epoxy resins still need to further reduce their curing shrinkage rate to expand their application range, especially in the fixing of precision electronic components.

[0031] In a first aspect, this application provides a spiral toroidal expanded monomer, the structural formula of which is shown in Formula I;

[0032]

[0033] The spirocyclic expandable monomer provided in this application possesses both spirocyclic and oxyheterocyclic groups, enabling it to combine advantages such as high reactivity, low shrinkage, and good resin compatibility. When added to an epoxy resin system, the spirocyclic and epoxy groups can undergo ring-opening copolymerization. After ring-opening, the intramolecular covalent bond length changes to the distance of intermolecular van der Waals forces, resulting in an expansion effect. However, the spirocyclic group itself has low reactivity and is difficult to integrate into the epoxy resin crosslinking network during curing. The oxyheterocyclic group in the spirocyclic expandable monomer of this application is a four-membered ring, exhibiting high reactivity and low shrinkage, making it easy to integrate into the epoxy resin. This ensures that the chain extension effect of the spirocyclic expandable monomer can expand the epoxy resin crosslinking network. The oxyheterocyclic group can also undergo ring-opening, transforming from a cyclic molecular chain to a straight chain, which can fill the volume space between epoxy resin molecular chains, further reducing the shrinkage caused by the change from intermolecular distance to interatomic distance during curing. The spirocyclic expanded monomer of this application can effectively reduce the curing shrinkage rate of epoxy resin under the synergistic effect of spirocyclic and oxyheterocyclic groups, thereby reducing curing shrinkage stress.

[0034] In some embodiments, the preparation method of the above-mentioned spirocyclic expanded monomer includes the following steps:

[0035] Under stirring, a mixture containing bis(trimethylolpropane) and an organic solvent is refluxed and dehydrated. Then, an alkaline catalyst, tetraethyl orthocarbonate, and diethyl carbonate are added. The bis(trimethylolpropane) and tetraethyl orthocarbonate are first synthesized to obtain a spirocyclic intermediate. The spirocyclic intermediate and diethyl carbonate undergo a transesterification reaction to obtain a spirocyclic expanded monomer.

[0036] In some embodiments, the organic solvent is selected from at least one of toluene, acetone, anhydrous ethanol, and ethyl acetate. In other embodiments, other solvents (such as xylene, cyclohexane, etc.) may also be used, as long as they do not affect the reaction. One or more of the above solvents may be used in combination, and the amount of solvent used during the synthesis process may be adjusted appropriately according to the homogeneity of the reaction system.

[0037] In the actual synthesis process, bis(trimethylolpropane) is added to an organic solvent and refluxed for dehydration under stirring. The stirring speed can be 200 r / min to 400 r / min. This application does not have specific requirements for the stirring time, as long as the bis(trimethylolpropane) is fully dissolved in the organic solvent.

[0038] In some embodiments, the reflux dehydration temperature is 100℃ to 125℃, specifically 100℃, 102℃, 105℃, 108℃, 110℃, 115℃, 120℃, or 125℃, or other values ​​within the above range, which are not limited here. The reflux dehydration time is 2h to 4h, specifically 2h, 2.5h, 3h, 3.2h, 3.5h, or 4h, or other values ​​within the above range, which are not limited here. In the actual synthesis process, after reflux dehydration, the reaction system is cooled to 85℃ to 115℃, and then an alkaline catalyst dissolved in anhydrous ethanol, along with appropriate amounts of tetraethyl orthocarbonate and diethyl carbonate, are added.

[0039] In some embodiments, the alkaline catalyst is selected from at least one of potassium hydroxide, sodium hydroxide, and lithium hydroxide. In other embodiments, the alkaline catalyst may also be lithium amide, alkali metal carbonates (e.g., sodium carbonate, potassium carbonate), or alkali metal bicarbonates (e.g., sodium bicarbonate, potassium bicarbonate). In the actual synthesis process, one alkaline catalyst or a mixture of multiple alkaline catalysts can be used, as long as the overall amount of alkaline catalyst added is controlled.

[0040] In some embodiments, the molar ratio of bis(trimethylolpropane) to tetraethyl orthocarbonate and diethyl carbonate is 1:(0.4-0.8):(1-1.5). Exemplarily, the molar ratio of bis(trimethylolpropane) to tetraethyl orthocarbonate and diethyl carbonate can be 1:0.4:1, 1:0.5:1, 1:0.6:1, 1:0.8:1, 1:0.6:1.1, 1:0.5:1.2, 1:0.5:1.3, or 1:0.5:1.5, etc., and of course, other values ​​within the above range are also possible and are not limited herein. Preferably, the molar ratio of bis(trimethylolpropane) to tetraethyl orthocarbonate and diethyl carbonate can be 1:0.5:1.

[0041] In some embodiments, the temperature of the transesterification reaction is 150°C to 180°C, specifically 150°C, 155°C, 160°C, 165°C, 170°C, 175°C or 180°C, etc., and of course other values ​​within the above range are also possible, which are not limited here.

[0042] In some embodiments, the transesterification reaction time is 3h to 5h, specifically 3h, 3.2h, 3.5h, 4h, 4.5h or 5h, etc., or other values ​​within the above range, which are not limited here.

[0043] During the transesterification reaction, the reaction is considered complete when no more bubbles are generated. The reaction product is then cooled to room temperature, poured into water, and repeatedly stirred and washed until the product is neutral.

[0044] The method for preparing expanded spirocyclic monomers provided in this application has a simple and controllable reaction process, a high yield of synthetic pathway, and the synthesized spirocyclic expanded monomers or oligomers of spirocyclic expanded monomers have high reactivity, low shrinkage, and good compatibility with epoxy resin systems.

[0045] Currently, the synthetic routes for existing spirocyclic monomers generally use organotin compounds. Organotin compounds are biotoxic, and the yields of these synthetic processes are low. For example, some synthetic routes are shown below:

[0046]

[0047] The synthetic route for the spirocyclic expanded monomer provided in this application does not use organotin and employs an alkaline catalytic transesterification reaction. The steps are relatively simple, and the yield can reach 70%-80%, which is better than the yield of approximately 50% of conventional organotin catalytic synthetic routes. The raw materials for the entire reaction are also low-toxicity materials. The synthetic route of this application has the advantages of high yield and low biotoxicity.

[0048] Secondly, this application provides a resin composition comprising an active component and an additive, wherein the active component comprises an epoxy resin and the aforementioned spirocyclic expanding monomer and / or oligomers of the spirocyclic expanding monomer.

[0049] In the above technical solution, the spirocyclic expanding monomer is applied to the resin composition containing epoxy resin to prepare a precision fixing adhesive, which can effectively reduce the shrinkage rate of the adhesive during the curing process, thereby reducing the curing shrinkage stress and improving the coupling accuracy. It is mainly used in the fields of electronic component bonding, optical device bonding and fixing.

[0050] In some embodiments, the weight ratio of epoxy resin to spirocyclic expanded monomer and / or oligomer of spirocyclic expanded monomer is (70-90):(10-30).

[0051] In some embodiments, the epoxy resin in the resin composition comprises 70 to 90 parts by weight, specifically 70, 72, 75, 78, 80, 82, 85, 89, or 90 parts, or other values ​​within the above range, which are not limited here. The weight percentage of epoxy resin can also be adjusted appropriately according to the actual application scenario. The weight percentage of spirocyclic expanded monomer and / or oligomer of spirocyclic expanded monomer can specifically be 10, 12, 15, 20, 22, 25, 28, or 30 parts, which are not limited here.

[0052] In some embodiments, the epoxy resin includes one or more of the following: aromatic ring epoxy resin, glycidyl ether epoxy resin, bisphenol A glycidyl ether epoxy resin, glycidyl ester epoxy resin, alicyclic epoxy resin, and hydrogenated bisphenol A epoxy resin.

[0053] In some embodiments, the epoxy resin is an alicyclic epoxy resin. Exemplarily, the alicyclic epoxy resin includes one or a combination of at least two of the following: 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate, methyl 3,4-epoxycyclohexanecarboxylate, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, and 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylate).

[0054] In some embodiments, the epoxy resin is an aromatic ring-containing epoxy resin. Exemplarily, aromatic ring-containing epoxy resins include one or a combination of at least two of the following: bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, biphenyl-type epoxy resin, bisphenol AD ​​epoxy resin, p-hydroxybenzoic acid, diglycidyl aniline, 1,1,2,2-tetra(p-hydroxyphenyl)ethane tetraglycidyl ether epoxy resin, and p-aminophenol triglycidyl epoxy resin.

[0055] In some embodiments, the epoxy equivalent in the epoxy resin is 100 g / mol to 300 g / mol, specifically 100 g / mol, 120 g / mol, 150 g / mol, 180 g / mol, 200 g / mol, 220 g / mol, 250 g / mol, 280 g / mol, or 300 g / mol, etc., or other values ​​within the above range, which are not limited here. Controlling the epoxy equivalent of the epoxy resin can ensure that the viscosity and stability of the resin composition meet the required values.

[0056] In some embodiments, based on 100 wt% of the active component, the resin composition further includes filler comprising 100 wt% to 150 wt% of the active component. The filler includes at least one of spherical silica powder, nano-titanium dioxide, and calcium carbonate powder. Preferably, the filler is spherical silica powder, i.e., silica particles, with a spherical shape and a particle size controllable within the range of 0.1 μm to 25 μm. Alternatively, a suitable filler can be selected based on the actual application scenario. The filler provided in this application has stable physicochemical properties. The addition of the filler helps improve the structural stability of the cured resin composition and further reduces the volume shrinkage rate of the resin composition.

[0057] In some embodiments, based on 100 wt% of the active component, the resin composition further includes a curing agent at a mass ratio of 10 wt% to 25 wt%, specifically 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 23 wt%, 25 wt%, etc., or other values ​​within the above range, which are not limited here. Preferably, the resin composition further includes a curing agent at a mass ratio of 10 wt% to 25 wt%, wherein the curing agent is methylhexahydrophthalic anhydride. In the resin composition of this application, the addition of an appropriate amount of methylhexahydrophthalic anhydride can change the stacking structure of methylhexahydrophthalic anhydride before and after the reaction with the epoxy resin. Methylhexahydrophthalic anhydride can form charge transfer complexes between and within molecules, causing the complex to change from close stacking to loose stacking, further reducing the curing shrinkage rate.

[0058] In some embodiments, based on 100 wt% of the active component, the resin composition further includes an initiator at a mass percentage of 1 wt% to 5 wt%, specifically 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 2 wt%, 3 wt%, 4 wt%, 4.5 wt%, or 5 wt%, etc., or other values ​​within the above range, which are not limited here. Preferably, the resin composition further includes an initiator at a mass percentage of 1 wt% to 1.5 wt%.

[0059] In some embodiments, the initiator is a cationic initiator selected from at least one of hexafluoroantimonate and hexafluorophosphate. Exemplarily, the cationic initiator may be hexafluoroantimonate CXC-1612, 6976, 6992, 261, etc., and is not limited thereto.

[0060] In some embodiments, the resin composition further includes acrylate monomers, and the initiator is a free radical initiator. Understandably, a free radical initiator can be added to the epoxy resin and acrylate system; the free radical initiator can be free radical initiator 184, 1173, 2959, etc., and is not limited thereto. It should be noted that the mass percentage of acrylate monomers added to the resin composition can be flexibly adjusted according to actual needs, and the acrylate monomers exhibit superior hardness and strength during the curing process.

[0061] In some embodiments, the resin composition is first pre-cured at 70°C for 1-2 hours, then cured at 110°C for 1-2 hours, and then cured at 150°C-170°C for 1-2 hours. The volume shrinkage rate of the resin composition during the curing process is 0.1%-0.6%, and the specific curing shrinkage rate can be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.6%, etc., or other values ​​within the above range, which are not limited here. Compared with the existing epoxy resin compositions with a curing shrinkage rate as high as 3%-7%, the resin composition provided in this application can reduce the curing shrinkage rate to below 0.6%, preferably below 0.5%, thereby significantly improving the curing shrinkage rate of the resin composition. The precision fixing adhesive prepared from the resin composition can effectively reduce the shrinkage rate of the adhesive during the curing process, thereby reducing the curing shrinkage stress and improving the coupling accuracy. It is mainly used in the fields of electronic component bonding, optical device bonding and fixing, etc.

[0062] This application also provides a method for preparing a resin composition, specifically including the following steps:

[0063] The epoxy resin can be dried in a vacuum chamber at 80°C for 24 hours. Weigh the required mass of the spirocyclic expanded monomer oligomer and epoxy resin, heat and stir at 60°C until completely miscible, then slowly cool to room temperature. Next, add a cationic initiator at a relative mass fraction of 1%–1.5% of the epoxy resin, along with different weight parts of spherical silica powder and curing agent methylhexahydrophthalic anhydride (MHHPA), and stir rapidly until homogeneous. Mix and degas in a vacuum planetary mixer, then immediately prepare the sample.

[0064] The sample curing method adopted a three-stage isothermal curing process. The thoroughly mixed sample was slowly poured into various polytetrafluoroethylene molds of various sizes determined according to the performance testing method, pre-cured at 70°C for 1 hour, cured at 110°C for 1 hour, and then post-cured at 150 or 170°C for 1 hour, finally obtaining a fully cured epoxy resin material.

[0065] This application also provides the application of the resin composition in electronic devices, mainly in the fields of chip bonding, optical device bonding and fixing, which can reduce the shrinkage rate during the resin curing process, thereby reducing curing shrinkage stress and improving coupling accuracy.

[0066] The embodiments of the present invention will be further described below with reference to several examples. However, the embodiments of the present invention are not limited to the specific embodiments described below. Appropriate modifications can be made within the scope of the original claims.

[0067] Synthesis of spirocyclic expanded monomers:

[0068] (1) Add the calculated amount of bis(trimethylolpropane) (DTMP) and toluene solvent to a three-necked flask connected to a Dean-Stark receiver and a reflux condenser. After stirring and refluxing at 100℃~125℃ for 2 hours to remove water, cool to 85℃~115℃, add potassium hydroxide dissolved in anhydrous ethanol, and the calculated amounts of tetraethyl orthocarbonate and diethyl carbonate. Stir for 2 hours, and collect the ethanol-toluene azeotrope to the theoretical amount. Raise the temperature to 150℃~180℃ and stir for 3~5 hours until no more bubbles are generated, then stop the reaction. Cool to room temperature, pour the product into water, and repeatedly stir and wash with water until the product is neutral to obtain the spirocyclic expanded monomer (yield 78%).

[0069]

[0070] The 1H NMR spectrum of the spirocyclic expanded monomer prepared in this embodiment is shown below. Figure 1 As shown, the Fourier transform infrared spectrum is as follows: Figure 2 As shown, the gel permeation chromatogram is as follows: Figure 3 As shown.

[0071] Preparation of resin composition:

[0072] Weigh the spirocyclic expanded monomer / oligomer and epoxy resin, as shown in Table 1. Heat and stir at 60°C until completely mixed, then slowly cool to room temperature. Next, add an initiator (hexafluoroantimonate, CXC-1612, molecular structure as shown in formula II-1) at a relative mass fraction of 1.5 wt% of the epoxy resin, as well as spherical silica powder and curing agent methyl hexahydrophthalic anhydride (abbreviated as MHHPA, molecular structure as shown in formula II-2) in different weight parts. Stir rapidly until homogeneous, then mix and degas in a vacuum planetary mixer. Finally, slowly pour the thoroughly mixed sample into a polytetrafluoroethylene mold of a size determined according to the performance testing method. Pre-cure at 70°C for 1 hour, cure at 110°C for 1 hour, and then cure at 170°C for 1 hour to obtain a fully cured epoxy resin material.

[0073] It should be noted that, in the embodiments of this application, the epoxy resin shown in formula a or formula b is used for performance testing. In actual applications, other types of epoxy resins can also be used, such as 1,2-epoxy-4-vinylcyclohexane, bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate, methyl 3,4-epoxycyclohexanecarboxylate, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, and 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylic acid), which are not limited here. The filler can also be other fillers besides silica powder, such as nano-titanium dioxide powder, etc.

[0074]

[0075]

[0076] Table 1. Components of the Resin Composition

[0077]

[0078]

[0079] Performance testing

[0080] 1) Curing shrinkage rate test of resin composition:

[0081] The standard test method for plastic density and relative density, ASTM D792-20, was used; the test results are shown in Table 2.

[0082] 2) Glass transition temperature test of resin composition:

[0083] The glass transition temperature (Tg) of the cured resin was measured using a DSC Q20 differential scanning calorimeter under a nitrogen atmosphere. The nitrogen gas flow rate was 50 mL / min, the heating rate was 3℃ / min, and the temperature range was 40–250℃. The test results are shown in Table 2.

[0084] Table 2. Performance test results of the resin

[0085]

[0086]

[0087] According to the test data of Examples 1-7, adding an appropriate amount of spirocyclic expanded monomer to epoxy resin 2021p (Formula a) can effectively reduce the shrinkage rate of the adhesive during the curing process, thereby reducing curing shrinkage stress and improving coupling accuracy. In Comparative Example 1, without the addition of spirocyclic expanded monomer, the curing shrinkage rate of the epoxy resin was significantly increased. In Comparative Example 2, without the addition of spirocyclic expanded monomer, the curing shrinkage rate of the epoxy resin was significantly increased. In Comparative Example 3, without the addition of spirocyclic expanded monomer, the curing shrinkage rate of the epoxy resin was significantly increased.

[0088] Compared to Example 2, Example 1 did not add methylhexahydrophthalic anhydride, and the curing shrinkage rate of the resin composition increased slightly. Similarly, compared to Example 8, Example 14 also did not add methylhexahydrophthalic anhydride, and the curing shrinkage rate of the resin composition increased slightly. It is evident that adding an appropriate amount of methylhexahydrophthalic anhydride to the resin composition can alter the stacking structure before and after the reaction between methylhexahydrophthalic anhydride and epoxy resin. Methylhexahydrophthalic anhydride can form charge-transfer complexes both intermolecularly and intramolecularly, causing the complex to change from close-packed to loose-packed. The synergistic effect of methylhexahydrophthalic anhydride and the spirocyclic expanding monomer can further reduce the curing shrinkage rate of the resin.

[0089] Similarly, according to the test data of Examples 8-14, adding an appropriate amount of spirocyclic expanded monomer to epoxy resin YX8000 (Formula b) can effectively reduce the shrinkage rate of the adhesive during the curing process, thereby reducing curing shrinkage stress and improving coupling accuracy. In Comparative Example 4, compared to Example 8, the epoxy resin without the addition of spirocyclic expanded monomer showed a significant increase in curing shrinkage rate. In Comparative Example 5, compared to Example 9, the epoxy resin without the addition of spirocyclic expanded monomer showed a significant increase in curing shrinkage rate. In Comparative Example 6, compared to Example 10, the epoxy resin without the addition of spirocyclic expanded monomer showed a significant increase in curing shrinkage rate.

[0090] In Examples 15 to 17, the addition of appropriate fillers to the resin compositions resulted in lower curing shrinkage rates. In Comparative Example 7, compared to Example 17, the absence of spirocyclic expanding monomers and methylhexahydrophthalic anhydride significantly increased the curing shrinkage rate of the resin.

[0091] In Examples 18 to 20, the addition of appropriate fillers to the resin compositions resulted in lower curing shrinkage rates. In Comparative Example 8, compared to Example 20, the absence of spirocyclic expanding monomers and methylhexahydrophthalic anhydride significantly increased the curing shrinkage rate of the resin.

[0092] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A spirocyclic expanded monomer, characterized in that, The structural formula of the spiral-ring expanded monomer is shown in Formula I; 2. A method for preparing a spirocyclic expanded monomer, characterized in that, The method includes the following steps: Under stirring, a mixture containing bis(trimethylolpropane) and an organic solvent is refluxed and dehydrated. Then, an alkaline catalyst, tetraethyl orthocarbonate, and diethyl carbonate are added. The bis(trimethylolpropane) and tetraethyl orthocarbonate are first synthesized to obtain a spirocyclic intermediate. The spirocyclic intermediate and diethyl carbonate undergo a transesterification reaction to obtain a spirocyclic expanded monomer.

3. The preparation method according to claim 2, characterized in that, It satisfies at least one of the following characteristics: 1) The organic solvent is selected from at least one of toluene, acetone, anhydrous ethanol, and ethyl acetate; 2) The temperature of the reflux dehydration treatment is 100℃~125℃, and the time of the reflux dehydration treatment is 2h~4h; 3) The alkaline catalyst is selected from at least one of potassium hydroxide and sodium hydroxide; 4) The molar ratio of the bis(trimethylolpropane) to the tetraethyl orthocarbonate and the diethyl carbonate is 1:(0.4-0.8):(1-1.5); 5) The temperature of the transesterification reaction is 150℃~180℃, and the time of the transesterification reaction is 3h~5h.

4. A resin composition, characterized in that, The resin composition includes an active component and an additive, wherein the active component includes an epoxy resin and the spirocyclic expanding monomer and / or oligomers of the spirocyclic expanding monomer as described in claim 1.

5. The resin composition according to claim 4, characterized in that, The weight ratio of the epoxy resin to the spirocyclic expanded monomer and / or the oligomer of the spirocyclic expanded monomer is (70-90):(10-30).

6. The resin composition according to claim 5, characterized in that, The epoxy resin includes one or more of the following: aromatic ring epoxy resin, glycidyl ether epoxy resin, bisphenol A glycidyl ether epoxy resin, glycidyl ester epoxy resin, alicyclic epoxy resin, and hydrogenated bisphenol A epoxy resin.

7. The resin composition according to claim 5, characterized in that, The epoxy resin is an alicyclic epoxy resin, and the epoxy equivalent in the alicyclic epoxy resin is 100 g / mol to 300 g / mol.

8. The resin composition according to claim 7, characterized in that, The alicyclic epoxy resin includes one or a combination of at least two of the following: 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate, methyl 3,4-epoxycyclohexanecarboxylate, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, and 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylate).

9. The resin composition according to claim 5, characterized in that, Based on 100 wt% of the active component, the resin composition further includes 100 wt% to 150 wt% of filler, wherein the filler includes at least one of spherical silica powder, nano titanium dioxide, and calcium carbonate powder.

10. The resin composition according to claim 5, characterized in that, Based on 100 wt% of the active component, the resin composition further includes a curing agent of 10 wt% to 25 wt% by mass, wherein the curing agent is methylhexahydrophthalic anhydride.

11. The resin composition according to claim 5, characterized in that, Based on 100 wt% of the active component, the resin composition further includes an initiator in a mass ratio of 1 wt% to 5 wt%, wherein the initiator is a cationic initiator selected from at least one of hexafluoroantimonate and hexafluorophosphate.

12. The resin composition according to claim 5, characterized in that, The resin composition is first pre-cured at 70°C for 1-2 hours, then cured at 110°C for 1-2 hours, and then cured at 150°C-170°C for 1-2 hours. The volume shrinkage rate of the resin composition during the curing process is 0.1%-0.6%.

13. The use of the resin composition according to any one of claims 4 to 12 in electronic devices.

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