Flexible transparent epoxy resin as well as preparation method and application thereof

Abstract

The invention discloses flexible transparent epoxy resin as well as a preparation method and application thereof.The preparation method comprises the following steps: firstly, adding an amino silane coupling agent into an epoxy resin monomer at normal temperature, and uniformly stirring to obtain a mixed solution; then heating the mixed solution for reaction, and after the reaction is finished, carrying out vacuum treatment on the reaction solution to obtain a precursor solution; and finally, carrying out curing treatment on the precursor solution to prepare the flexible transparent epoxy resin. The preparation method is simple in process and reasonable in design, and the obtained flexible epoxy resin has good mechanical strength, thermal stability and transparency.

Description

Technical Field

[0001] The invention belongs to the technical field of epoxy resin development, and relates to a flexible transparent epoxy resin and a preparation method and application thereof. Background Art

[0002] Epoxy resin is widely used in electronic packaging, adhesives, coatings and other fields due to its excellent mechanical strength, chemical resistance and thermal stability. Before curing, epoxy resin is a thermoplastic linear structure. When used, a curing agent is added, and the curing agent reacts with the epoxy group of the epoxy resin to become a macromolecule with a network structure, becoming a thermosetting finished product. In the development of modern engineering and materials science, the high brittleness of traditional epoxy resins has limited their use in certain applications that require high flexibility and impact resistance. In order to solve this problem, a variety of methods have been used in the prior art to prepare flexible epoxy resins, such as introducing flexible segments, adding plasticizers and rubber toughening, etc.

[0003] The development of flexible epoxy resin stems from the demand for improvement of traditional rigid epoxy resin. Flexible epoxy resin not only retains the excellent properties of epoxy resin, but also enhances its deformation ability under stress and broadens its application range. In terms of performance, it has strong impact resistance. When subjected to heavy load impact, flexible epoxy resin can better disperse energy and reduce damage. At present, the preparation methods of flexible epoxy resin mainly include the introduction of flexible segments, rubber toughening, low cross-linking density, chemical modification, addition of plasticizers, etc. Although the prior art has improved the flexibility of epoxy resin to a certain extent by introducing flexible segments, plasticizers and rubber toughening, there are still some shortcomings. For example, the introduction of flexible segments and plasticizers may reduce the mechanical strength and thermal stability of the material, and the long-term use of plasticizers may lead to plasticizer migration and performance degradation. In addition, some toughening methods require complex preparation processes or expensive raw materials, which increases production costs. Some plasticizers and rubber materials have potential impacts on the environment and health, limiting their application. At the same time, in the field of electronic packaging, most of the current flexible epoxy resins lack transparency, making it difficult for the packaged materials to have a certain degree of visibility for easy detection and maintenance. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a flexible transparent epoxy resin and a preparation method and application thereof, thereby solving the technical problems in the prior art that the introduction of flexible segments and plasticizers into epoxy resins will reduce the mechanical strength and thermal stability of epoxy resin materials, and the long-term use of plasticizers will lead to plasticizer migration and performance degradation, while improving the technical problem in the prior art that the flexible epoxy resins are lacking in transparency and have poor properties.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a flexible transparent epoxy resin comprises the following steps:

[0007] S1: adding the aminosilane coupling agent to the epoxy resin monomer at room temperature, stirring evenly to obtain a mixed solution;

[0008] S2: continuously stirring and heating the mixed solution to react, and after the reaction is completed, vacuum treating the reaction solution to obtain a precursor solution;

[0009] S3: curing the precursor solution to obtain the flexible transparent epoxy resin.

[0010] Preferably, the epoxy resin monomer is one of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin and glycidyl ester epoxy resin.

[0011] Preferably, the aminosilane coupling agent is one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl)-γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropyltriethoxysilane, and N-β (aminoethyl)-γ-aminopropyltriethoxysilane.

[0012] Preferably, in step S1, the mass ratio of the epoxy resin to the aminosilane coupling agent is (5-21):(1.5-10).

[0013] Preferably, in step S1, the stirring speed is 100 to 500 rpm, and the stirring time is 10 to 60 min.

[0014] Preferably, in step S2, during the temperature-raising reaction, the reaction temperature is 25 to 80° C., the reaction time is 20 to 60 min, and the stirring rate during the reaction is 100 to 500 rpm.

[0015] Preferably, in step S2, during vacuum treatment, the vacuum degree is 0.6 to 1 atmosphere, and the treatment time is 10 to 30 minutes.

[0016] Preferably, in step S3, during the curing treatment, the temperature is 80 to 120° C. and the time is 6 to 24 hours.

[0017] A flexible transparent epoxy resin is prepared by the method.

[0018] The above-mentioned flexible transparent epoxy resin is used in the field of flexible electronic packaging.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] The invention discloses a method for preparing a flexible transparent epoxy resin. In the method, an aminosilane coupling agent is introduced, and the aminosilane coupling agent and an epoxy resin monomer are reacted under a temperature increase condition. The temperature increase process promotes the volatilization of hydrolysis products of the aminosilane coupling agent itself, and promotes a cross-linking reaction between the amino groups in the hydrolysis products and the epoxy groups of the epoxy resin. Then, the reaction products are vacuum treated to remove excess bubbles in the system, and finally a curing treatment is performed. During the curing treatment process, the epoxy resin and the hydrolysis products of the aminosilane coupling agent are further cross-linked to obtain the flexible transparent epoxy resin. In the flexible transparent epoxy resin, the introduction of silicon-oxygen bonds (Si-O) makes the epoxy resin have good flexibility. At the same time, the silicon-oxygen bonds also maintain the rigidity of the epoxy resin through cross-linking reactions, and the amino groups help to improve the effect of the curing reaction. This balance enables the material to better disperse stress when subjected to external forces, thereby improving the mechanical strength. In addition, the silicon-oxygen bonds have higher bond energy and can remain stable at high temperatures, thereby improving the thermal stability of the epoxy resin. At the same time, due to the cross-linking reaction of the aminosilane coupling agent and the epoxy resin, a denser network structure is formed, which limits the movement of the molecular chain at high temperatures, thereby improving the thermal stability. In addition, in the epoxy During the preparation of the resin, only an aminosilane coupling agent is introduced. The aminosilane coupling agent contains two functional groups, amino and silane. The two functional groups can react chemically with the epoxy group of the epoxy resin respectively, thereby enhancing the compatibility between the resin and the filler. Good compatibility helps to reduce interface scattering and improve the transparency of the material. The aminosilane coupling agent can promote the orderly arrangement of resin molecules during the curing process to form a more uniform and dense network structure. This structure is conducive to the rectilinear propagation of light, reduces scattering, and thus improves transparency. In addition, vacuum treatment of the reaction solution can effectively remove bubbles in the system, reduce light scattering, and is also conducive to improving transparency. Therefore, the process of the present invention is simple, the design is reasonable, and the obtained flexible epoxy resin has good mechanical strength, thermal stability and transparency.

[0021] Furthermore, the epoxy resin monomer is one of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin and glycidyl ester epoxy resin. First of all, these epoxy resin monomers have high chemical stability and weather resistance, and can maintain their stable performance under various environmental conditions, which is particularly important for preparing flexible transparent epoxy resin materials that need to be used for a long time; in addition, these epoxy resin monomers can form transparent or translucent materials after curing. By optimizing the formula and process conditions, their transparency can be further improved to meet the application scenarios with high requirements for optical properties; at the same time, these epoxy resin monomers can form materials with high mechanical strength after curing, and they can withstand certain external forces such as stretching, bending and impact, ensuring the stability and durability of the material during use; in addition, after the introduction of aminosilane coupling agent, these epoxy resin monomers can increase the flexibility of the material while maintaining a certain mechanical strength, which is of great significance for the preparation of flexible transparent epoxy resin materials that need to have both rigidity and flexibility.

[0022] Furthermore, the aminosilane coupling agent is one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl)-γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropyltriethoxysilane, and N-β (aminoethyl)-γ-aminopropyltriethoxysilane. First, the amino group in the aminosilane coupling agent molecule can react with the epoxy group of the epoxy resin to form a chemical bond, which significantly enhances the interfacial bonding force of the resin and helps to improve the overall performance and transparency of the material. In addition, the addition of the aminosilane coupling agent can also reduce the viscosity of the resin and improve the fluidity, making the resin easier to operate during mixing, pouring and molding. At the same time, good processing performance also helps to reduce bubbles and defects generated during processing, further improving the transparency of the material. At the same time, in addition to improving transparency, the aminosilane coupling agent can also enhance the mechanical properties of the epoxy resin by enhancing the interfacial bonding force and improving the resin network structure.

[0023] Furthermore, in step S1, the mass ratio of the epoxy resin to the aminosilane coupling agent is (5-21 g): (1.5-10 g). First, this ratio range allows a performance balance to be found between the epoxy resin and the aminosilane coupling agent. Too little coupling agent cannot fully exert its role in enhancing interfacial bonding and improving compatibility, while too much coupling agent may cause the resin system to be too viscous, reduce processing performance, and may even affect the final transparency. Therefore, the selection of this ratio range helps to avoid unnecessary negative effects while ensuring material performance; in addition, an appropriate amount of aminosilane coupling agent can improve the compatibility between the resin and the filler, reduce interface scattering, and thus improve the transparency of the material. The setting of this ratio range helps to ensure the uniform distribution of the coupling agent in the resin and avoid the decrease in transparency caused by local excess or deficiency; the aminosilane coupling agent helps to improve the mechanical properties of the material, such as tensile strength, flexural strength and impact toughness, by enhancing the interfacial bonding between the resin and the filler. The selection of this ratio range can ensure that the coupling agent fully exerts its reinforcing effect in the resin, while avoiding excessive performance or cost increase caused by excessive addition. In addition, the right amount of aminosilane coupling agent can reduce the viscosity of epoxy resin, improve fluidity, and thus improve processing performance, which helps to reduce the generation of bubbles and defects during mixing, pouring and molding, and further improve the transparency and overall quality of the material.

[0024] Further, in step S1, the speed during stirring is 100-500rpm, and the stirring time is 10-60min. First, stirring is a key step to fully mix the epoxy resin and the aminosilane coupling agent. Appropriate speed and stirring time can ensure that the two materials are evenly mixed at the molecular level to avoid excessive or low local concentrations, which helps to form a uniform resin system, thereby improving the overall performance and transparency of the material. Appropriate stirring speed and time can promote contact and collision between reactants and accelerate the chemical reaction, which helps to shorten the curing time, improve production efficiency, and may improve the final performance of the material. During the stirring process, the appropriate speed and time help to discharge the bubbles generated during the mixing process and reduce the defects inside the material. The presence of bubbles and defects will significantly reduce the transparency and mechanical properties of the material. Therefore, by optimizing the stirring conditions, a more dense and transparent epoxy resin material can be prepared. Of course, excessive shear force can also cause molecular chain breakage or structural damage. Therefore, controlling the stirring speed and time within an appropriate range can avoid this adverse effect.

[0025] Further, in step S2, during the temperature-raising reaction, the reaction temperature is 25 to 80°C, the reaction time is 20 to 60 min, and the stirring rate during the reaction is 100 to 500 rpm. First, the appropriate reaction temperature can accelerate the chemical reaction between the epoxy resin and the aminosilane coupling agent. Within this temperature range, the movement speed of the reactant molecules is accelerated, and the collision frequency is increased, thereby increasing the reaction rate, which helps to achieve a higher reaction conversion rate in a short time and ensure the full progress of the curing reaction; in addition, although high temperature helps to accelerate the reaction, excessively high temperature may cause thermal degradation of the epoxy resin or coupling agent, affecting the performance of the material. Controlling the reaction temperature below 80°C can effectively avoid this overheating degradation phenomenon and protect the chemical structure and physical properties of the material. At the same time, during the temperature-raising reaction, maintaining an appropriate stirring rate is crucial to achieving uniform mixing of the reactants. The stirring rate range of 100 to 500 rpm can ensure that the temperature, concentration and reactant distribution in the reaction system are uniform, thereby avoiding problems such as local overheating, uneven concentration or reactant aggregation. As for the reaction time, a too short reaction time will lead to incomplete reaction, affecting the strength and transparency of the material, while a too long reaction time may increase production costs and reduce production efficiency. Controlling the reaction time within the range of 20 to 60 minutes can ensure that the reaction is fully carried out while avoiding unnecessary time waste.

[0026] Further, in step S2, during vacuum treatment, the vacuum degree is 0.6 to 1 atmosphere, and the treatment time is 10 to 30 minutes. Here, vacuum treatment can significantly reduce the pressure in the system, making it easier for bubbles in the epoxy resin to escape. The presence of these bubbles and volatiles will seriously affect the transparency and mechanical properties of the material; in addition, under vacuum conditions, the distance between epoxy resin molecules will be relatively reduced, and the interaction force between molecules will be enhanced, which will help promote the rearrangement of molecular chains and the cross-linking reaction, making the curing reaction more sufficient and uniform. At the same time, the vacuum environment can also reduce the interference of impurities such as oxygen on the curing reaction and improve the reaction efficiency. In addition, with the removal of bubbles and volatiles and the rearrangement of molecular chains, the compactness of the epoxy resin material will be significantly improved, and the improvement of compactness will help enhance the mechanical properties (such as tensile strength, bending strength, etc.) and weather resistance of the material, while reducing the water absorption and permeability of the material. In addition, although vacuum treatment itself does not directly accelerate the curing reaction, it creates more favorable conditions for subsequent curing reactions by removing bubbles and promoting molecular rearrangement. Therefore, the curing reaction after vacuum treatment can often be completed faster, thereby shortening the entire production cycle.

[0027] Further, in step S3, during the curing treatment, the temperature is 80-120°C and the time is 6-24h. First, within this temperature range, the cross-linking reaction between the epoxy resin and the aminosilane coupling agent can be fully carried out. The higher temperature accelerates the movement of molecules, increases the collision frequency between the reactants, and thus increases the rate of the curing reaction. A sufficiently long treatment time ensures that the reaction can be completed thoroughly, avoiding the performance degradation caused by incomplete curing. Secondly, the curing treatment not only transforms the resin system from liquid to solid, but also forms a three-dimensional network structure through cross-linking reaction. This structure gives the material excellent mechanical properties (such as strength, hardness, toughness, etc.) and chemical resistance. Appropriate curing temperature and time can optimize the formation of this network structure and make the material performance reach the best state. In addition, the epoxy resin material after curing has higher thermal stability and chemical stability. At high temperatures, the material can maintain its shape and performance unchanged; when in contact with various chemical substances, it is not easy to swell, dissolve or degrade. This stability is crucial for maintaining the performance of the material during long-term use. Appropriate curing temperature and time can slow down the shrinkage rate and make the shrinkage more uniform, thereby reducing deformation and cracking of the material. This is especially important for the preparation of high-precision and high-requirement products. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 The relevant reaction formulas involved in the preparation of the flexible transparent epoxy resin in the present invention include the hydrolysis equation of the aminosilane coupling agent (1), the cross-linking and curing reaction equation of the hydrolysis product of the aminosilane coupling agent and the epoxy group in the epoxy resin (2), and the cross-linking reaction equation of the hydrolysis product of the aminosilane coupling agent itself to form a [Si-O] bond (3);

[0030] Figure 2 The flexible transparent epoxy resin prepared in Example 2 of the present invention is a flexibility test diagram and a side view of the degree of transparency, wherein (a) is a schematic diagram of the flexible transparent epoxy resin when it is bent, and (b) is a schematic diagram of the flexible transparent epoxy resin rebounding to its original shape after bending;

[0031] Figure 3 This is a DSC test chart of the flexible transparent epoxy resin prepared in Example 2 of the present invention;

[0032] Figure 4It is the infrared spectra of epoxy resin monomer (b) and flexible transparent epoxy resin (a) prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0034] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0035] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0036] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0037] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0038] like Figure 1 As shown, the present invention provides a method for preparing a flexible transparent epoxy resin, comprising the following steps:

[0039] S1: adding the aminosilane coupling agent to the epoxy resin monomer at room temperature, stirring evenly to obtain a mixed solution;

[0040] The epoxy resin monomer is one of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin and glycidyl ester epoxy resin.

[0041] The aminosilane coupling agent is one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl)-γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropyltriethoxysilane and N-β (aminoethyl)-γ-aminopropyltriethoxysilane.

[0042] The mass ratio of the epoxy resin to the aminosilane coupling agent is (5-21):(1.5-10).

[0043] The rotation speed during stirring is 100-500 rpm, and the stirring time is 10-60 min.

[0044] In a preferred embodiment, the aminosilane coupling agent is added under stirring, wherein the stirring speed is 100 to 500 rpm. The stirring treatment in the present invention may be mechanical stirring.

[0045] S2: Continue stirring and heat the mixed solution to react. After the reaction is completed, vacuum treat the reaction solution to obtain a precursor solution. The temperature-raising reaction may be carried out in a water bath.

[0046] In the temperature-raising reaction process, the reaction temperature is 25-80° C., the reaction time is 20-60 min, and the stirring rate is 100-500 rpm.

[0047] During vacuum treatment, the vacuum degree is 0.6 to 1 atmosphere, and the treatment time is 10 to 30 minutes.

[0048] In this process, the temperature rise first promotes the hydrolysis of the aminosilane coupling agent, as shown in reaction formula (1), because its own alkalinity will hydrolyze itself at room temperature to form silanol and methanol, and then the methanol can be volatilized by temperature treatment; at the same time, the temperature rise reaction promotes the cross-linking and curing reaction between the amino group on the hydrolyzed aminosilane coupling agent and the epoxy group on the epoxy resin. The principle can be compared with the reaction between the curing agent and the epoxy resin. The active hydrogen on the amino group and the epoxy group undergo a ring-opening reaction, and the cross-linking structure formed by the covalent bond completes the curing, as shown in reaction formula (2).

[0049] S3: Curing the precursor solution to obtain the flexible transparent epoxy resin. During the curing process, the cross-linking and curing between the hydroxyl groups on the hydrolyzed aminosilane coupling agent is further promoted. As shown in reaction formula (3), after the aminosilane coupling agent is hydrolyzed, the hydrolysis product has three -OH bonds, which undergo a polycondensation reaction, thereby forming a [Si-O] bond with a certain degree of flexibility in the flexible transparent epoxy resin, which effectively improves the mechanical strength of the epoxy resin.

[0050] During the curing process, the temperature is 80 to 120° C. and the time is 6 to 24 hours.

[0051] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0052] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0053] Example 1

[0054] A method for preparing a flexible transparent epoxy resin comprises the following steps:

[0055] (1) Add 21 g of bisphenol A epoxy resin into a beaker, add 13.86 g of γ-aminopropyltrimethoxysilane under stirring at a speed of 400 rpm, and continue mechanical stirring for reaction at a stirring speed of 400 rpm for 20 min to obtain a mixed solution;

[0056] (2) reacting the mechanically stirred mixed solution in a water bath, with continuous mechanical stirring at 300 rpm, a water bath temperature of 30° C., and a reaction time of 20 min;

[0057] (3) The reaction solution in step (2) was taken out and placed in a vacuum drying oven and evacuated to 0.6 atmospheres twice, with each time holding time of 5 minutes.

[0058] (4) After the precursor solution treated in step (3) is poured into a specific mold, it is placed in a forced air drying oven at 100° C. for 12 hours to obtain a flexible transparent epoxy resin.

[0059] Example 2

[0060] A method for preparing a flexible transparent epoxy resin comprises the following steps:

[0061] (1) Add 7 g of bisphenol F epoxy resin into a beaker and add 1.54 g of γ-aminopropyltriethoxysilane under stirring at a speed of 200 rpm. Continue mechanical stirring to react. The stirring speed is 200 rpm and the reaction time is 15 min.

[0062] (2) treating the mechanically stirred mixed solution in a water bath and continuing the mechanical stirring reaction at a stirring speed of 200 rpm, a water bath temperature of 80° C., and a reaction time of 45 min;

[0063] (3) The mixed solution in step (2) was taken out and placed in a vacuum drying oven and evacuated to 0.9 atmospheres for 5 times, with each time holding time of 5 minutes.

[0064] (4) After the precursor solution treated in step (3) is poured into a specific mold, it is placed in a forced air drying oven at 80° C. for 12 hours to obtain a flexible transparent epoxy resin.

[0065] Example 3

[0066] A method for preparing a flexible transparent epoxy resin comprises the following steps:

[0067] (1) Add 12 g of polyphenol type glycidyl ether epoxy resin into a beaker, add 3.94 g of N-β (aminoethyl) -γ-aminopropyl trimethoxysilane under stirring at a speed of 300 rpm, and continue mechanical stirring for reaction at a stirring speed of 300 rpm for 30 min;

[0068] (2) treating the mechanically stirred mixed solution in a water bath, with the mechanical stirring speed being 200 rpm, the water bath temperature being 60° C., and the reaction time being 35 min;

[0069] (3) The mixed solution in step (2) was taken out and placed in a vacuum drying oven and evacuated to 0.9 atmospheres twice, with each time holding time of 10 minutes.

[0070] (4) After the precursor solution treated in step (3) is poured into a specific mold, it is placed in a forced air drying oven at 100° C. for 24 hours to obtain a flexible transparent epoxy resin.

[0071] Example 4

[0072] A method for preparing a flexible transparent epoxy resin comprises the following steps:

[0073] (1) 8 g of aliphatic glycidyl ether epoxy resin was added to a beaker, and 1.32 g of N-β (aminoethyl) -γ-aminopropyl triethoxysilane was added under stirring at a speed of 500 rpm, and mechanical stirring was continued at a speed of 300 rpm for 10 min;

[0074] (2) treating the mechanically stirred mixed solution in a water bath, the mechanical stirring speed is 300 rpm, the water bath temperature is 75° C., and the reaction time is 25 min;

[0075] (3) The mixed solution in step (2) was taken out and placed in a vacuum drying oven and evacuated once at 0.9 atmospheres for 15 minutes.

[0076] (4) After the precursor solution treated in step (3) is poured into a specific mold, it is placed in a forced air drying oven at 120° C. for 6 hours to obtain a flexible transparent epoxy resin.

[0077] Example 5

[0078] A method for preparing a flexible transparent epoxy resin comprises the following steps:

[0079] (1) Add 13.5 g of glycidyl ester epoxy resin into a beaker, add 1.78 g of N-β (aminoethyl) -γ-aminopropyl triethoxysilane under stirring at 250 rpm, and continue mechanical stirring for 45 min;

[0080] (2) treating the mechanically stirred mixed solution in a water bath, with the mechanical stirring speed being 250 rpm, the water bath temperature being 65° C., and the reaction time being 60 min;

[0081] (3) The mixed solution in step (2) was taken out and placed in a vacuum drying oven and evacuated at 0.8 atmospheres for 3 times, with each time holding time of 10 minutes.

[0082] (4) After the precursor solution treated in step (3) is poured into a specific mold, it is placed in a forced air drying oven at 110° C. for 12 hours to obtain a flexible transparent epoxy resin.

[0083] The flexible transparent epoxy resins prepared in Examples 1 to 5 all have good flexibility and transparency. The flexible transparent epoxy resin prepared in Example 2 is used as an example for description.

[0084] Figure 2 The flexible test diagram and the side view of the transparency of the flexible transparent epoxy resin prepared in Example 2 of the present invention are shown, wherein (a) is a schematic diagram of the flexible transparent epoxy resin when it is bent, and (b) is a schematic diagram of the flexible transparent epoxy resin rebounding to its original shape after bending. As can be seen from the figure, before bending, it can be seen that this flexible transparent epoxy resin maintains the transparency of the epoxy resin monomer. When deformed by external force, it will spontaneously restore its original state, and has excellent flexibility and impact resistance. The epoxy group can also be seen through the flexible transparent epoxy resin, and it can be seen that it has a certain degree of transparency.

[0085] Figure 3This is a DSC test chart of the flexible transparent epoxy resin prepared in Example 2 of the present invention. According to the DSC chart, it can be seen that the epoxy resin and the aminosilane coupling agent have an exothermic reaction starting from room temperature, and the reaction is most intense at 80°C, with the highest exothermic peak. It can be seen that the optimal reaction curing temperature of the epoxy resin and the aminosilane coupling agent is 80°C, and a flexible transparent epoxy resin is finally prepared.

[0086] Figure 4 The infrared spectra of epoxy resin monomer and flexible transparent epoxy resin are shown in Figure 2. Figure 4 From the infrared spectrum of the epoxy resin monomer in (a), we can see that the characteristic absorption peaks of the epoxy group can be seen at 910cm-1 and 830cm-1, which are the stretching vibrations of the COC bond of the epoxy group; the peaks at 1250cm-1 and 1025cm-1 correspond to the stretching vibrations of the ether bond COC, indicating the presence of ether bonds in the molecule; the stretching vibrations of the CH bond on the aromatic ring can be seen at 3050cm-1, which is the characteristic peak of aromatic compounds; the peaks at 1600cm-1 and 1500cm-1 correspond to the stretching vibrations of the benzene ring skeleton, which are absorption peaks unique to aromatic rings. Figure 4 In (b), it can be seen that after the cross-linking reaction of epoxy resin and coupling agent, the corresponding epoxy group peak disappears, indicating that the epoxy groups have all been ring-opened and reacted. Comparing the peaks of (a) and (b), it is found that the stretching vibration peak of Si-O-Si bond appears at 1087cm-1, indicating that Si-O-Si bond appears during the reaction.

[0087] Example 6

[0088] A method for preparing a flexible transparent epoxy resin comprises the following steps:

[0089] S1: Adding aminosilane coupling agent to epoxy resin monomer at room temperature, stirring evenly to obtain a mixed solution; wherein the epoxy resin monomer is bisphenol A epoxy resin. The aminosilane coupling agent is γ-aminopropyltrimethoxysilane. The mass ratio of epoxy resin to aminosilane coupling agent is 5:1.5. The stirring speed is 100 rpm and the stirring time is 60 min.

[0090] S2: Continue stirring and heat the mixed solution to react. After the reaction is completed, vacuum treat the reaction solution to obtain a precursor solution. During the temperature reaction, the reaction temperature is 25°C, the reaction time is 60 minutes, and the stirring rate is 500 rpm. During the vacuum treatment, the vacuum degree is 0.6 atmospheres and the treatment time is 30 minutes.

[0091] S3: curing the precursor solution to obtain the flexible transparent epoxy resin, wherein the curing temperature is 80° C. and the curing time is 24 hours.

[0092] Example 7

[0093] A method for preparing a flexible transparent epoxy resin comprises the following steps:

[0094] S1: Adding aminosilane coupling agent to epoxy resin monomer at room temperature, stirring evenly to obtain a mixed solution; wherein the epoxy resin monomer is polyphenol glycidyl ether epoxy resin. The aminosilane coupling agent is γ-aminopropyltriethoxysilane. The mass ratio of epoxy resin to aminosilane coupling agent is 21:10. The stirring speed is 500 rpm and the stirring time is 10 min.

[0095] S2: Continue stirring and heat the mixed solution to react. After the reaction is completed, vacuum treat the reaction solution to obtain a precursor solution. During the temperature reaction, the reaction temperature is 80°C, the reaction time is 20 minutes, and the stirring rate is 100 rpm. During the vacuum treatment, the vacuum degree is 1 atmosphere and the treatment time is 10 minutes.

[0096] S3: curing the precursor solution to obtain the flexible transparent epoxy resin, wherein the curing temperature is 120° C. and the curing time is 6 hours.

[0097] Example 8

[0098] A method for preparing a flexible transparent epoxy resin comprises the following steps:

[0099] S1: Add the aminosilane coupling agent to the epoxy resin monomer at room temperature, stir evenly, and obtain a mixed solution; wherein the epoxy resin monomer is an aliphatic glycidyl ether epoxy resin. The aminosilane coupling agent is N-β (aminoethyl) -γ-aminopropyl triethoxysilane. The mass ratio of epoxy resin to aminosilane coupling agent is 10:4. The stirring speed is 200 rpm and the stirring time is 40 min.

[0100] S2: Continue stirring and heat the mixed solution to react. After the reaction is completed, vacuum treat the reaction solution to obtain a precursor solution. During the temperature reaction, the reaction temperature is 50°C, the reaction time is 4 minutes, and the stirring rate is 300 rpm. During the vacuum treatment, the vacuum degree is 0.8 atmospheres and the treatment time is 20 minutes.

[0101] S3: curing the precursor solution to obtain the flexible transparent epoxy resin, wherein the curing temperature is 100° C. and the curing time is 15 hours.

[0102] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a flexible transparent epoxy resin, characterized in that: The following steps are involved: S1: adding the aminosilane coupling agent to the epoxy resin monomer at room temperature, stirring evenly to obtain a mixed solution; S2: continuously stirring and heating the mixed solution to react, and after the reaction is completed, vacuum treating the reaction solution to obtain a precursor solution; S3: curing the precursor solution to obtain the flexible transparent epoxy resin.

2. The method for preparing a flexible transparent epoxy resin according to claim 1, characterized in that: The epoxy resin monomer is one of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin and glycidyl ester epoxy resin.

3. The method for preparing a flexible transparent epoxy resin according to claim 1, characterized in that: The aminosilane coupling agent is one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl)-γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropyltriethoxysilane and N-β (aminoethyl)-γ-aminopropyltriethoxysilane.

4. The method for preparing a flexible transparent epoxy resin according to claim 1, characterized in that: In step S1, the mass ratio of the epoxy resin to the aminosilane coupling agent is (5-21):(1.5-10).

5. The method for preparing a flexible transparent epoxy resin according to claim 1, characterized in that: In step S1, the rotation speed during stirring is 100 to 500 rpm, and the stirring time is 10 to 60 min.

6. The method for preparing a flexible transparent epoxy resin according to claim 1, characterized in that: In step S2, during the temperature-raising reaction, the reaction temperature is 25 to 80° C., the reaction time is 20 to 60 min, and the stirring rate is 100 to 500 rpm.

7. The method for preparing a flexible transparent epoxy resin according to claim 1, characterized in that: In step S2, during the vacuum treatment, the vacuum degree is 0.6 to 1 atmosphere, and the treatment time is 10 to 30 minutes.

8. The method for preparing a flexible transparent epoxy resin according to claim 1, characterized in that: In step S3, during the curing treatment, the temperature is 80 to 120° C. and the time is 6 to 24 hours.

9. A flexible transparent epoxy resin, characterized in that: It is prepared by the method according to any one of claims 1 to 8.

10. Use of the flexible transparent epoxy resin as claimed in claim 9 in the field of flexible electronic packaging.

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