Application of Monte Carlo tree search in design of component proportioning and curing program, epoxy resin and preparation method and application thereof

Abstract

The invention provides application of Monte Carlo tree search in design of epoxy resin component proportioning and curing procedures, epoxy resin and a preparation method and application of the epoxy resin, and belongs to the technical field of polymer-based composite materials. The invention provides application of Monte Carlo tree search in epoxy resin component proportioning and curing program design, epoxy resin designed by adopting Monte Carlo tree search only comprises composite epoxy resin and a curing agent, and the composite epoxy resin comprises bifunctional epoxy resin and tetrafunctional epoxy resin. According to the invention, by controlling the ratio of the two composite epoxy resins with different epoxy values and functionalities, the regulation and control of mechanical properties and thermal properties can be realized, and compared with a system independently selecting one epoxy resin, the adjustment space is larger, and the balance of both mechanical properties and thermal properties can be realized more easily.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer-based composite materials, and specifically relates to the application of Monte Carlo tree search in epoxy resin formulation and curing program design, epoxy resin and a preparation method and application thereof. Background Art

[0002] Advanced polymer-based composite materials are widely used in daily life and production due to their excellent mechanical properties. The development of resin matrices with both high mechanical properties and high thermal properties is of great significance for improving the performance of advanced polymer composite materials. However, when considering mechanical properties alone, the high strength and high modulus of the resin usually cannot coexist with high toughness. The increase in polymer modulus and strength often leads to a decrease in its toughness, and it is even more difficult when taking thermal properties into account. The thermal properties of materials, such as glass transition temperature, often show an opposite trend to the toughness of the material. It is difficult to obtain a resin system that balances the above properties, which requires a lot of manpower, material resources and time.

[0003] Epoxy resin is widely used in the structural field due to its excellent mechanical properties, thermal stability, chemical resistance, adhesive properties and dimensional stability, mainly because after curing, epoxy resin has a highly cross-linked structure. However, such a high cross-linking density also brings inherent brittleness to epoxy resin, resulting in poor crack propagation resistance and strong restrictions on its application.

[0004] In the prior art, the flexibility of cured epoxy resins is usually improved by adding rubber particles containing functional groups, thermoplastic polymers, nanofillers or forming interpenetrating networks. However, the existing methods have many problems. While improving flexibility, other properties (glass transition temperature, tensile modulus, etc.) are often reduced, thereby limiting the application space of epoxy resins.

[0005] At present, the optimization algorithms widely used in the industrial field include genetic algorithms and Bayesian optimization. Genetic algorithms (GA) utilize human evolution mechanisms (such as crossover and mutation) and have been widely used to solve optimization problems. Genetic algorithms require sufficient prior data to adjust numerous parameters to obtain optimal performance. However, in material design problems, there is not so much prior data. Bayesian optimization (BO) is an effective global optimization method, especially suitable for dealing with problems such as material design that lack a lot of prior data. Bayesian optimization predicts the possible values ​​of the objective function by constructing a probabilistic model (such as Gaussian process) and selects the optimal sampling points based on this. This method can effectively find parameter combinations close to the global optimal solution with a limited number of experiments or calculations. However, since the uncertainty of the prediction requires the evaluation of all candidates in the search space, BO faces serious challenges in over-computation in large-scale problems commonly seen in material design.

[0006] Since the size of the candidate space is exponentially proportional to the input dimension of the black box function, in the joint optimization problem of the amine / epoxy curing system formula and process in this work, the input parameters involve the formula and process, the input dimension is 8 dimensions, and the candidate space is huge. Therefore, it is urgent to find an optimization method suitable for high dimensions and huge search space. Summary of the invention

[0007] The purpose of the present invention is to provide an application of Monte Carlo tree search in epoxy resin formulation and curing program design, epoxy resin and its preparation method and application. The present invention adopts Monte Carlo tree search to design epoxy resin formulation, and the prepared epoxy resin has four excellent properties of tensile strength, tensile modulus, elongation at break and glass transition temperature.

[0008] In order to achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0009] Application of Monte Carlo tree search in the design of epoxy resin component ratio and curing schedule.

[0010] Preferably, the application of the Monte Carlo tree search comprises the following steps:

[0011] Set the proportion of bifunctional epoxy resin in the composite epoxy resin to x1, and set the mass of the curing agent to x2;

[0012] Using the T-β extrapolation method and the DSC curves of epoxy resin / curing agent at different heating rates, the temperature range and time range of the three-stage curing program are obtained, x3 to x8, where x3 is the temperature of the first curing, x4 is the time of the first curing, x5 is the temperature of the second curing, x6 is the time of the second curing, x7 is the temperature of the third curing, and x8 is the time of the third curing;

[0013] Determine the glass transition temperature, tensile strength, tensile modulus and elongation at break of the epoxy resin, the dimension is 8 dimensions, set the initial point of the first round to 2(n+1), that is, 18 points, divide the space of the 18 points of the first round in the 8-dimensional space according to formula I, so as to find the possible range of the specific values ​​of the component ratio and / or curing procedure of the epoxy resin when the performance of the epoxy resin reaches the target as the most promising area, that is, when the points are less than 5, perform Bayesian optimization on the current space according to formula I, select a suitable space, perform Bayesian optimization in the corresponding space, select the point with higher EI according to formula IV, and perform the next round of iteration;

[0014] Each iteration performs the following steps: selection, expansion, simulation, and back propagation; at the beginning of each iteration, there is a point at the top of the tree when the Monte Carlo tree search is used to divide the space as the root node. Starting from the root node, the k-means clustering algorithm is used to divide the area ΩA into ΩB representing high performance and ΩC representing low performance, ΩA = ΩB ∪ ΩC;

[0015] In the selection step, the region with greater potential is selected by judging whether there is a possible highest value, and the UCB value of each node is calculated by formula I:

[0016]

[0017] In Formula I, z i is the value of the child node, which is a comprehensive indicator of epoxy resin performance. i is the number of visits to the node, V parent is the total number of visits to the parent node of the child node, and C represents the degree of exploration;

[0018] The comprehensive index is obtained by formula II:

[0019] Score = w1x Tg +w2x σ +w3x E +W4x δ Formula II;

[0020] Among them, Score is a comprehensive index of epoxy resin performance, X Tg , X σ , X E and X δThey refer to the glass transition temperature, tensile strength, tensile modulus and elongation at break of epoxy resin respectively;

[0021] W1, W2, W3 and W4 are weighted coefficients, which are obtained by formula III:

[0022]

[0023] x0 is the performance target value of the epoxy resin's glass transition temperature, tensile strength, tensile modulus and elongation at break, k is a fixed constant, and x is a single performance;

[0024] In the expansion, the selected child node continues to expand downward according to formula I until a leaf node is reached;

[0025] In the simulation, new points are introduced in the selected leaf nodes, and BO is used to introduce new sampling points;

[0026] In the back propagation, each node is traced back and the number of visits and value of each node is updated, and the next round of iteration is prepared until the set performance standard is reached;

[0027]

[0028] In Formula IV, μ(x) and σ(x) are the posterior mean and posterior standard deviation of the score in Formula II, respectively. f(x*) is the comprehensive performance index (score) of the group with the best performance currently obtained. x* is the current best comprehensive performance formula. φ(Z) and are the cumulative distribution function and probability distribution function of the standard normal distribution respectively.

[0029] The present invention provides an epoxy resin, comprising a composite epoxy resin and a curing agent; the mass ratio of the composite epoxy resin to the curing agent is 1:0.25-0.8;

[0030] The composite epoxy resin comprises a difunctional epoxy resin and a tetrafunctional epoxy resin; the mass ratio of the difunctional epoxy resin to the tetrafunctional epoxy resin is 22.5-30:67.5-70;

[0031] The epoxy value of the bifunctional epoxy resin is 0.44-0.56 mol / 100g; the epoxy value of the tetrafunctional epoxy resin is 0.75-0.83 mol / 100g.

[0032] Preferably, the bifunctional epoxy resin is bisphenol A epoxy resin; and the tetrafunctional epoxy resin is tetrafunctional glycidylamine epoxy resin.

[0033] Preferably, the bisphenol A type epoxy resin is bisphenol A diglycidyl ether; and the tetrafunctional glycidylamine epoxy resin is N,N,N',N'-tetracyclyl-4,4'-diaminodiphenylmethane.

[0034] Preferably, the curing agent is an amine curing agent.

[0035] Preferably, the molar ratio of the total epoxy groups in the composite epoxy resin to the active hydrogen in the curing agent is 1:0.8-1.4.

[0036] The present invention also provides a method for preparing the epoxy resin described in the above technical solution, comprising the following steps:

[0037] The composite epoxy resin and the curing agent are mixed, and defoaming and curing are performed in sequence to obtain the epoxy resin.

[0038] Preferably, the curing comprises sequentially performing a first curing, a second curing and a third curing;

[0039] The first curing temperature is 135-160°C and the time is 120-240 minutes;

[0040] The second curing temperature is 155-180°C and the time is 120-240 minutes;

[0041] The temperature of the third curing is 180-200° C., and the time is 120-300 minutes.

[0042] The present invention also provides the use of the epoxy resin described in the above technical solution or the epoxy resin prepared by the preparation method described in the above technical solution as a structural part of an aircraft, an automobile or a tire.

[0043] The invention provides an application of Monte Carlo tree search in epoxy resin formula and curing program design. The Monte Carlo tree search is adopted to design the epoxy resin formula; the epoxy resin comprises a composite epoxy resin and a curing agent; the mass ratio of the composite epoxy resin to the curing agent is 1:0.25-0.8; the composite epoxy resin comprises a difunctional epoxy resin and a tetrafunctional epoxy resin; the mass ratio of the difunctional epoxy resin to the tetrafunctional epoxy resin is 22.5-30:67.5-70; the epoxy value of the difunctional epoxy resin is 0.44-0.56 mol / 100 g; the epoxy value of the tetrafunctional epoxy resin is 0.75-0.83 mol / 100 g. The epoxy resin of the present invention only includes a composite epoxy resin and a curing agent. The present invention can achieve the regulation of mechanical properties and thermal properties by controlling the ratio of two composite epoxy resins with different epoxy values ​​and functionalities. Compared with the single selection of an epoxy resin system, the adjustment space is larger and it is easier to achieve a balance between mechanical properties and thermal properties. In addition, the present invention can further achieve the regulation of mechanical properties and thermal properties by controlling the coordination between the molar ratio of the epoxy group in the epoxy resin and the active hydrogen in the curing agent. It can be seen from the results of the embodiments of the present invention that the epoxy resin prepared by the present invention has a tensile strength of >111.6MPa, a tensile modulus of >4GPa, an elongation at break of >6%, and a glass transition temperature of >180°C. It has four excellent properties that are better than most pure epoxy resins at present, and even better than some epoxy resin products after enhancement and modification. It can be used as a resin matrix of advanced materials for high-performance material structural parts.

[0044] The present invention also provides a method for preparing the epoxy resin described in the above technical solution, and further obtains an epoxy resin with excellent performance by controlling three different curing temperatures and curing times. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 DSC curves of epoxy resin / curing agent at different heating rates;

[0047] Figure 2 Schematic diagrams of Monte Carlo tree search and Bayesian optimization; (a) is a schematic diagram of Monte Carlo tree search, and (b) is a schematic diagram of Bayesian optimization;

[0048] Figure 3 Performance scoring chart for the initial point and the subsequent 5 rounds of optimization points;

[0049] Figure 4 The DSC curves of the resin solutions of the homogeneous systems obtained in Comparative Examples 9 and 10 and Example 1;

[0050] Figure 5 It is a tensile (stress-strain) curve diagram of the epoxy resin material specimens obtained in Comparative Examples 9 and 10 and Example 1;

[0051] Figure 6 This is a viscosity comparison chart of the epoxy resin material sample strip obtained in Example 1 of the present invention and the 33DDS sample strip. DETAILED DESCRIPTION

[0052] The invention provides the application of Monte Carlo tree search in the design of epoxy resin component ratio and curing program.

[0053] In the present invention, the application of the Monte Carlo tree search includes the following steps:

[0054] Set the proportion of bifunctional epoxy resin in the composite epoxy resin to x1, and set the mass of the curing agent to x2;

[0055] Using the T-β extrapolation method and the DSC curves of epoxy resin / curing agent at different heating rates, the temperature range and time range of the three-stage curing program are obtained, x3 to x8, where x3 is the temperature of the first curing, x4 is the time of the first curing, x5 is the temperature of the second curing, x6 is the time of the second curing, x7 is the temperature of the third curing, and x8 is the time of the third curing;

[0056] Determine the glass transition temperature, tensile strength, tensile modulus and elongation at break of the epoxy resin, the dimension is 8 dimensions, set the initial point of the first round to 2(n+1), that is, 18 points, divide the space of the 18 points of the first round in the 8-dimensional space according to formula I, so as to find the possible range of the specific values ​​of the component ratio and / or curing procedure of the epoxy resin when the performance of the epoxy resin reaches the target as the most promising area, that is, when the points are less than 5, perform Bayesian optimization on the current space according to formula I, select a suitable space, perform Bayesian optimization in the corresponding space, select the point with higher EI according to formula IV, and perform the next round of iteration;

[0057] Each iteration performs the following steps: selection, expansion, simulation, and back propagation; at the beginning of each iteration, there is a point at the top of the tree when the Monte Carlo tree search is used to divide the space as the root node. Starting from the root node, the k-means clustering algorithm is used to divide the area ΩA into ΩB representing high performance and ΩC representing low performance, ΩA = ΩB ∪ ΩC;

[0058] In the selection step, the region with greater potential is selected by judging whether there is a possible highest value, and the UCB value of each node is calculated by formula I:

[0059]

[0060] In Formula I, z i is the value of the child node, which is a comprehensive indicator of epoxy resin performance. i is the number of visits to the node, V parent is the total number of visits to the parent node of the child node, and C represents the degree of exploration;

[0061] The comprehensive index is obtained by formula II:

[0062] Score = w1x Tg +w2x σ +w3x E +W4x δ Formula II;

[0063] Among them, Score is a comprehensive index of epoxy resin performance, X Tg , X σ , X E and X δ They refer to the glass transition temperature, tensile strength, tensile modulus and elongation at break of epoxy resin respectively;

[0064] W1, W2, W3 and W4 are weighted coefficients, which are obtained by formula III:

[0065]

[0066] x0 is the performance target value of the epoxy resin's glass transition temperature, tensile strength, tensile modulus and elongation at break, k is a fixed constant, and x is a single performance;

[0067] In the expansion, the selected child node continues to expand downward according to formula I until a leaf node is reached;

[0068] In the simulation, new points are introduced in the selected leaf nodes, and BO is used to introduce new sampling points;

[0069] In the back propagation, each node is traced back and the number of visits and value of each node is updated, and the next round of iteration is prepared until the set performance standard is reached;

[0070]

[0071] In Formula IV, μ(x) and σ(x) are the posterior mean and posterior standard deviation of the score in Formula II, respectively. *) is the comprehensive performance index (score) of the group with the best performance at present, x * It is the best comprehensive performance formula currently, φ(Z) and are the cumulative distribution function and probability distribution function of the standard normal distribution respectively.

[0072] The present invention limits the comprehensive index scores of sampling points with very high values ​​of certain targets and very low values ​​of other targets through the above method, and sampling points with high values ​​of four targets are more likely to obtain higher comprehensive index scores.

[0073] The present invention provides an epoxy resin, comprising a composite epoxy resin and a curing agent; the mass ratio of the composite epoxy resin to the curing agent is 1:0.25-0.8;

[0074] The composite epoxy resin comprises a difunctional epoxy resin and a tetrafunctional epoxy resin; the mass ratio of the difunctional epoxy resin to the tetrafunctional epoxy resin is 22.5-30:67.5-70;

[0075] The epoxy value of the bifunctional epoxy resin is 0.44-0.56 mol / 100 g; the epoxy value of the tetrafunctional epoxy resin is 0.75-0.83 mol / 100 g.

[0076] In the present invention, unless otherwise specified, all preparation raw materials are preferably commercially available products well known to those skilled in the art.

[0077] In the present invention, the composite epoxy resin includes a difunctional epoxy resin and a tetrafunctional epoxy resin; the difunctional epoxy resin is a bisphenol A epoxy resin, the bisphenol A epoxy resin is bisphenol A diglycidyl ether (DEGBA), and the specific model may be E-51 or EBA-65; the tetrafunctional epoxy resin is a tetrafunctional glycidylamine epoxy resin, the multifunctional glycidylamine resin is N,N,N',N'-tetracyclyl-4,4'-diaminodiphenylmethane (TGDDM), and the specific model may be AG80 or AG601.

[0078] In the present invention, the epoxy value of the composite epoxy resin is the amount of epoxy group contained in 100g of epoxy resin; the functionality is the number of epoxy groups contained in a single composite epoxy resin molecule; the epoxy group is conventional in the art and may be an ethylene oxide group; the active hydrogen of the curing agent is the active hydrogen on the nitrogen atom in the molecular structure.

[0079] In the present invention, the epoxy value of the bifunctional epoxy resin is 0.44-0.56 mol / 100 g, and in a specific embodiment, it can be 0.46 mol / 100 g, 0.51 mol / 100 g or 0.55 mol / 100 g; the viscosity of the bifunctional epoxy resin at 25±1°C is 1600-2000 mPa·s, and in a specific embodiment, it can be 1700 mPa·s, 1800 mPa·s or 1900 mPa·s.

[0080] In the present invention, the epoxy value of the tetrafunctional epoxy resin is 0.75-0.83 mol / 100 g, and in a specific embodiment, it can be 0.78 mol / 100 g, 0.80 mol / 100 g or 0.82 mol / 100 g; the viscosity of the tetrafunctional epoxy resin at 25±1°C is 4000-6000 mPa·s, and in a specific embodiment, it can be 4500 mPa·s, 5000 mPa·s or 5500 mPa·s.

[0081] In the present invention, the curing agent is an amine curing agent; the amine curing agent is an aromatic polyamine curing agent, and in a specific embodiment, it can be ethyltoluenediamine, m-phenylenediamine, 1,3-bis(3-aminophenoxy)benzene (1,3,3APB), 1,3-bis(4-aminophenoxy)benzene or 1,4-bis(4-aminophenoxy)benzene.

[0082] In the present invention, the mass ratio of the composite epoxy resin to the curing agent is 1:0.25-0.8. In a specific embodiment, the mass ratio can be 1:0.3, 1:0.5, 1:0.6 or 1:0.7.

[0083] In the present invention, the molar ratio of the total epoxy groups in the composite epoxy resin to the active hydrogen in the curing agent is 1:0.8-1.4. In specific embodiments, it can be 1:0.9, 1:1, 1:1.1, 1:1.2 or 1:1.3.

[0084] The present invention also provides a method for preparing the epoxy resin described in the above technical solution, comprising the following steps:

[0085] The composite epoxy resin and the curing agent are mixed, and defoaming and curing are performed in sequence to obtain the epoxy resin.

[0086] In the present invention, the mixing temperature is 70-90°C, and in a specific embodiment, it can be 80°C or 85°C; the time is 1-2h, and in a specific embodiment, it can be 1.5h; the mixing is conventional stirring in the art, and a stirring rod or magnetic stirring can be used; the present invention has no special limitation on the stirring rate.

[0087] In the present invention, the defoaming temperature is 60-80°C, and in a specific embodiment, it can be 65°C or 70°C; the defoaming time is 1-2h, and in a specific embodiment, it can be 1.5h.

[0088] In the present invention, the curing includes sequentially performing a first curing, a second curing and a third curing; the temperature of the first curing is 135 to 160° C., and in a specific embodiment, it can be 136° C., 145° C. or 157° C.; the time is 120 to 240 minutes, and in a specific embodiment, it can be 127 minutes or 150 minutes;

[0089] The second curing temperature is 155-180°C, in a specific embodiment, it can be 160°C, 165°C or 172°C; the time is 120-240min, in a specific embodiment, it can be 179min or 185min;

[0090] The temperature of the third curing is 180-200° C., and in a specific embodiment, it can be 185° C. or 193° C.; the time is 120-300 min, and in a specific embodiment, it can be 146 min or 165 min.

[0091] In the present invention, the epoxy resin may also be added with polyethersulfone (PES), silica, graphene, polyphenylene sulfide (PPS) and bismaleimide resin (BMI) to achieve higher mechanical properties and thermal properties, and obtain epoxy resin products with other functionalities.

[0092] The present invention also provides the use of the epoxy resin described in the above technical solution or the epoxy resin prepared by the preparation method described in the above technical solution as a structural part of an aircraft, an automobile or a tire.

[0093] In the present invention, the structural parts include the fuselage and wings of an aircraft and the body frame of an automobile.

[0094] In order to further illustrate the present invention, the epoxy resin provided by the present invention and its preparation method and application are described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0095] The bifunctional epoxy resin used in the following examples of the present invention is epoxy resin E-51, purchased from Shanghai Huayi Resin Co., Ltd., and its parameters are as follows: viscosity (25±1°C), 1600-2000mPa·s; epoxy value: 0.51mol / 100g; non-volatile matter: ≥99.5%.

[0096] The tetrafunctional epoxy resin is epoxy resin AG80 purchased from Shanghai Huayi Resin Co., Ltd., and its parameters are as follows: viscosity (25±1°C), 4000-6000 mPa·s; epoxy value: 0.8 mol / 100 g; non-volatile matter: ≥98.5%.

[0097] Example 1

[0098] Determination of epoxy resin formula ratio

[0099] The mass proportion of the E-51 resin system is set to x1, and the value range of x1 is 0-1, which represents the proportion of E-51 in the two epoxy resins in the system; the amount of curing agent 1,3,3APB is set to x2, and x2 represents the ratio of the amine value of the curing agent in the system to the epoxy functional group in the epoxy system, and the range of x2 is set to 0.8-1.4.

[0100] Resin curing schedule determination

[0101] The T-β extrapolation method is used to determine the optimal temperature parameters of the curing process. i , T p , T f Plotting the heating rate, we get Figure 1 The DSC curves of epoxy resin / curing agent at different heating rates are shown in Figure 1, and then linear fitting is performed on them. When β=0, three extrapolated temperatures are obtained, and the theoretical gel temperature (T i *), theoretical curing temperature (T p *) and theoretical post-treatment temperature (T f *).

[0102] By observing the DSC curve of the two resins mixed at a mass ratio of 1:1 and then adding the curing agent, it was found that there was an obvious and single exothermic peak at different heating rates, which indicates that when the two resins are mixed, the curing reaction with the curing agent is completed in one step; and it was found that the exothermic peak of the resin has a significant correlation with the heating rate. As the temperature increases, the exothermic peak moves toward the high temperature direction and the peak value increases. In the DSC curve, the temperature T at which the curing reaction starts can also be obtained. i , curing reaction peak temperature T p And the temperature T at which the curing reaction ends f , all three move to the high temperature zone with the increase of heating rate, as shown in Table 1.

[0103] Table 1 Scanning thermodynamic parameters at different heating rates obtained from DSC curves, and the theoretical reaction temperature obtained by extrapolation

[0104]

[0105] According to Table 1, by extrapolating the DSC curve obtained by mixing E-51 and AG80 in a ratio of 1:1, T i , T p , T f They are 139℃, 172℃, and 209℃ respectively. The resin of this ratio can be kept at 139℃ for a period of time, then heated to 172℃ at a certain heating rate, kept for a period of time, and then raised to 209℃ for post-treatment to make the resin fully react and cure completely. The above data can provide a rough reference range for the curing temperature of the compound resin system.

[0106] Table 2 Temperature range and time range of the three-stage curing program obtained based on the theoretical reaction temperature

[0107]

[0108]

[0109] According to the theoretical gel temperature (Ti*), theoretical curing temperature (Tp*) and theoretical post-processing temperature (Tf*) obtained by DSC extrapolation, the curing temperature range as shown in Table 2 can be obtained. Taking into account the degree of curing, based on experience, the approximate range of curing time can be obtained. In this way, the temperature range (T1-T3) and time range (t1-t3) of the three curing intervals are obtained, and x3-x8 are used to replace these 6 values. In this way, 8 unknowns x1-x8 are obtained. Determining these 8 unknowns can obtain the formula of the above resin system and the curing procedure, thereby obtaining the specific performance of the resin under this procedure.

[0110] Taking into account the mechanical and thermal properties of the resin, the output properties are set to tensile strength, tensile modulus, elongation at break, and glass transition temperature, four properties commonly used in industrial production applications. This process can be optimized using a computer and the experiments can be repeated iteratively.

[0111] Considering that the dimension is 8 dimensions, according to experience, the initial points of the first round are 2(n+1), that is, 18 points. The Monte Carlo tree search is performed on the 18 points of the first round in the 8-dimensional space according to Formula I to select a suitable space, and Bayesian optimization is performed in the corresponding space to select points with higher EI to guide the next round of experiments.

[0112] After the above Monte Carlo tree search, Bayesian optimization, and experimental iteration process, 3 points were obtained in the second round, 2 points in the third round, 3 points in the fourth round, and 3 points in the fifth round. In the fifth round, i.e., the 28th sample, the required performance was obtained. The specific ratio and curing procedure are as follows:

[0113] Weigh 22.5 g of E-51, 67.5 g of AG80, and 57.9 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at 90° C. with a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution.

[0114] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0115] Then, the stainless steel mold containing the resin solution was placed in an oven for curing, and the curing procedure was 157° C. for 127 min, 172° C. for 179 min, and 193° C. for 146 min. After the resin solution was naturally cooled to room temperature, a brown sample of epoxy resin was obtained.

[0116] Example 2

[0117] Weigh 30g of EBA-65, 70g of AG601, and 31.85g of m-phenylenediamine, and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at a constant temperature of 50°C using a magnetic stirrer for 1 to 1.5 hours until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution;

[0118] The resin solution was poured into a stainless steel mold preheated at 70°C, and then the mold was placed in a vacuum oven at 70°C for 1 hour to remove bubbles in the resin solution;

[0119] Then, the stainless steel mold containing the resin solution was placed in an oven for curing, and the curing procedure was 136° C. for 127 min, 160° C. for 179 min, and 180° C. for 146 min. After the resin solution was naturally cooled to room temperature, a brown sample of epoxy resin was obtained.

[0120] Comparative Example 1

[0121] Weigh 10.2 g of E-51, 74.8 g of AG80, and 46.725 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture with a magnetic stirrer at a constant temperature of 90° C. for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to obtain a homogeneous system of the resin solution;

[0122] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0123] Then, the stainless steel mold containing the resin solution was placed in an oven for curing, and the curing procedure was 160° C. for 123 min, 162° C. for 205 min, and 193° C. for 218 min. After the resin solution was naturally cooled to room temperature, a brown sample of epoxy resin was obtained.

[0124] Comparative Example 2

[0125] Weigh 1.8 g of E-51, 88.2 g of AG80, and 79 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at a constant temperature of 90° C. using a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution.

[0126] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0127] The stainless steel mold containing the resin solution was then placed in an oven for curing. The curing procedure was 159°C for 129 min, 163°C for 202 min, and 190°C for 177 min. After the resin solution cooled naturally to room temperature, a brown epoxy resin strip was obtained.

[0128] Comparative Example 3

[0129] Weigh 9 g of E-51, 81 g of AG80, and 70.492 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at a constant temperature of 90° C. using a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution.

[0130] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0131] The stainless steel mold containing the resin solution was then placed in an oven for curing. The curing procedure was 157°C for 132 min, 164°C for 207 min, and 199°C for 194 min. After the resin solution cooled naturally to room temperature, a brown epoxy resin strip was obtained.

[0132] Comparative Example 4

[0133] Weigh 18.9 g of E-51, 71.1 g of AG80, and 54.935 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at a constant temperature of 90° C. using a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution.

[0134] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0135] The stainless steel mold containing the resin solution was then placed in an oven for curing. The curing procedure was 159°C for 124 min, 172°C for 140 min, and 195°C for 150 min. After the resin solution cooled naturally to room temperature, a brown epoxy resin strip was obtained.

[0136] Comparative Example 5

[0137] Weigh 13.5 g of E-51, 76.5 g of AG80, and 66.678 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at a constant temperature of 90° C. using a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution;

[0138] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0139] The stainless steel mold containing the resin solution was then placed in an oven for curing. The curing procedure was 157°C for 124 min, 169°C for 184 min, and 191°C for 148 min. After the resin solution cooled naturally to room temperature, a brown epoxy resin strip was obtained.

[0140] Comparative Example 6

[0141] Weigh 26.1 g of E-51, 63.9 g of AG80, and 44.734 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at a constant temperature of 90° C. using a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution;

[0142] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0143] The stainless steel mold containing the resin solution was then placed in an oven for curing. The curing procedure was 138°C for 172 min, 162°C for 148 min, and 200°C for 242 min. After the resin solution cooled naturally to room temperature, a brown epoxy resin strip was obtained.

[0144] Comparative Example 7

[0145] Weigh 39.6 g of E-51, 50.4 g of AG80, and 38.406 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at a constant temperature of 90° C. using a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous phase of the resin solution.

[0146] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0147] The stainless steel mold containing the resin solution was then placed in an oven for curing. The curing procedure was 136°C for 236 min, 172°C for 183 min, and 197°C for 177 min. After the resin solution cooled naturally to room temperature, a brown epoxy resin strip was obtained.

[0148] Comparative Example 8

[0149] Weigh 17.1 g of E-51, 72.9 g of AG80, and 36.561 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at a constant temperature of 90° C. using a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution.

[0150] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0151] The stainless steel mold containing the resin solution was then placed in an oven for curing. The curing procedure was 155°C for 122 min, 177°C for 124 min, and 194°C for 238 min. After the resin solution cooled naturally to room temperature, a brown epoxy resin strip was obtained.

[0152] Comparative Example 9

[0153] Weigh 90 g of E-51 and 42.097 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at 90° C. with a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution.

[0154] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0155] Then, the stainless steel mold containing the resin solution was placed in an oven for curing. The curing procedure was 150°C for 180 min, 180°C for 180 min, and 210°C for 180 min. After the resin solution was naturally cooled to room temperature, a brown epoxy resin strip was obtained.

[0156] Comparative Example 10

[0157] Weigh 90 g of AG80 and 40.252 g of 1,3-bis(3-aminophenoxy) and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at 90° C. with a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution.

[0158] The resin solution was poured into a stainless steel mold preheated at 80°C, and then the mold was placed in a vacuum oven at 80°C for 1 h to remove bubbles in the resin solution;

[0159] Then, the stainless steel mold containing the resin solution was placed in an oven for curing, and the curing procedure was 150° C. for 180 min, 180° C. for 180 min, and 210° C. for 180 min. After the resin solution was naturally cooled to room temperature, a brown epoxy resin strip was obtained.

[0160] Comparative Example 11

[0161] Weigh 22.5 g of E-51, 67.5 g of AG80, and 40.6 g of 33DDS, and place them in a single-mouth round-bottom flask with a vacuum joint to obtain a mixture. Under vacuum, stir the mixture at a constant temperature of 130° C. using a magnetic stirrer for 1 to 1.5 h until all the amine curing agent is completely dissolved in the composite epoxy resin to form a homogeneous system of the resin solution;

[0162] The resin solution was poured into a stainless steel mold preheated at 100°C, and then the mold was placed in a vacuum oven at 100°C for 1 h to remove bubbles in the resin solution;

[0163] The stainless steel mold containing the resin solution was then placed in an oven for curing, and the curing procedure was 157° C. for 127 min, 172° C. for 179 min, and 193° C. for 146 min. After the resin solution was naturally cooled to room temperature, a brown sample strip of epoxy resin (referred to as 33DDS) was obtained.

[0164] Test Case

[0165] The present invention tests the glass transition temperature of the mechanical properties and thermal properties of the epoxy resins obtained in Examples 1 and 2 and Comparative Examples 1 to 10 by the following method:

[0166] Resin glue DSC test of epoxy resin glass transition temperature:

[0167] The homogeneous systems of the resin solutions prepared in Examples 1 and 2 of the present invention and Comparative Examples 1 to 10 were immediately subjected to DSC testing after being uniformly mixed, under the following conditions: nitrogen atmosphere, heating from 25°C to 250°C at 5°C / min; keeping at 250°C for 1 min; cooling to 30°C at 20°C / min; keeping at 30°C for 1 min, and heating to 220°C at 10°C / min, and the glass transition temperature of the epoxy resin was calculated through the heating curve.

[0168] The glass transition temperature is determined in accordance with GB / T 19466.1-2004.

[0169] Tensile properties test of cured epoxy resin:

[0170] The epoxy resins obtained in Examples 1 and 2 and Comparative Examples 1 to 10 were made into dumbbell-shaped tensile specimens, and the tensile properties were tested in accordance with GB / T2567-2021. The results are shown in Table 3.

[0171] Table 3 Performance test results of epoxy resin obtained in Examples 1 to 11

[0172]

[0173] It can be seen from the results in Table 3 that the present invention optimizes the formula and curing procedure of the epoxy resin and uses a Monte Carlo number search method to greatly reduce the number of epoxy resin systems that have both mechanical properties and thermal properties.

[0174] Figure 4 The DSC curves of the resin solutions of the homogeneous systems obtained in Comparative Examples 9 and 10 and Example 1 are shown in FIG. Figure 4 The results show that comparative examples 9 and 10 are the DSC images of two epoxy resins cured separately, and example 1 is the DSC image after the two epoxy resins are compounded, indicating that the curing temperature does not have a significant effect after the two resins are compounded, and it is a single peak, and the two resins are cured simultaneously at a certain temperature.

[0175] Figure 5 is a tensile (stress-strain) curve of the epoxy resin material strips obtained in Comparative Examples 9 and 10 and Example 1, Figure 5 The results show that comparative examples 9 and 10 are the mechanical properties of the two epoxy resins E-51AG80 after curing separately, and embodiment 1 is the mechanical properties image of the two epoxy resins after curing, which shows that the AG80 system has a larger mechanical property modulus and a lower elongation at break in the separate case, while the E-51 system has a smaller modulus and a higher elongation at break. The compounded resin will neutralize the advantages and disadvantages of the two resins, thereby obtaining a higher tensile strength.

[0176] According to the standard of GB / T 22235-2008, the viscosity of the epoxy resin material specimen obtained in Example 1 and 33DDS was tested at 80°C using a rotational viscometer. The results are as follows:

[0177] Figure 6 : is a viscosity comparison diagram of the epoxy resin material strip obtained in Example 1 of the present invention and the 33DDS strip; Figure 6 It can be seen that the viscosity of the 33DDS system is greater than 100,000 mps·s at 80°C, while the epoxy resin material strip obtained in Example 1 of the present invention has a viscosity below 5,000 mps·s, which is relatively low and has a better experimental processing window.

[0178] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. Application of Monte Carlo tree search in the design of epoxy resin component ratio and curing program.

2. The use according to claim 1, characterized in that: The application of the Monte Carlo tree search comprises the following steps: Set the proportion of bifunctional epoxy resin in the composite epoxy resin to x1, and set the mass of the curing agent to x2; Using the T-β extrapolation method and the DSC curves of epoxy resin / curing agent at different heating rates, the temperature range and time range of the three-stage curing program are obtained, x3 to x8, where x3 is the temperature of the first curing, x4 is the time of the first curing, x5 is the temperature of the second curing, x6 is the time of the second curing, x7 is the temperature of the third curing, and x8 is the time of the third curing; Determine the glass transition temperature, tensile strength, tensile modulus and elongation at break of the epoxy resin, the dimension is 8 dimensions, set the initial point of the first round to 2(n+1), that is, 18 points, divide the space of the 18 points of the first round in the 8-dimensional space according to formula I, so as to find the possible range of the specific values ​​of the component ratio and / or curing procedure of the epoxy resin when the performance of the epoxy resin reaches the target as the most promising area, that is, when the points are less than 5, perform Bayesian optimization on the current space according to formula I, select a suitable space, perform Bayesian optimization in the corresponding space, select the point with higher EI according to formula IV, and perform the next round of iteration; Each iteration performs the following steps: selection, expansion, simulation, and back propagation; at the beginning of each iteration, there is a point at the top of the tree when the Monte Carlo tree search is used to divide the space as the root node. Starting from the root node, the k-means clustering algorithm is used to divide the area ΩA into ΩB representing high performance and ΩC representing low performance, ΩA = ΩB ∪ ΩC; In the selection step, the region with greater potential is selected by judging whether there is a possible highest value, and the UCB value of each node is calculated by formula I: In Formula I, z i is the value of the child node, which is a comprehensive indicator of epoxy resin performance. i is the number of visits to the node, V parent is the total number of visits to the parent node of the child node, and C represents the degree of exploration; The comprehensive index is obtained by formula II: Score=w1x Tg +w2x σ +w3x E +w4x δ Formula II; Among them, Score is a comprehensive index of epoxy resin performance, X Tg , X σ , X E and X δ They refer to the glass transition temperature, tensile strength, tensile modulus and elongation at break of epoxy resin respectively; W1, W2, W3 and W4 are weighted coefficients, which are obtained by formula III: x0 is the performance target value of the epoxy resin's glass transition temperature, tensile strength, tensile modulus and elongation at break, k is a fixed constant, and x is a single performance; In the expansion, the selected child node continues to expand downward according to formula I until a leaf node is reached; In the simulation, new points are introduced in the selected leaf nodes, and BO is used to introduce new sampling points; In the back propagation, each node is traced back and the number of visits and value of each node is updated, and the next round of iteration is prepared until the set performance standard is reached; In Formula IV, μ(x) and σ(x) are the posterior mean and posterior standard deviation of the score in Formula II, respectively. * ) is the comprehensive performance index (score) of the group with the best performance at present, x * It is the best comprehensive performance formula currently, Φ(Z) and are the cumulative distribution function and probability distribution function of the standard normal distribution respectively.

3. An epoxy resin, characterized in that It comprises a composite epoxy resin and a curing agent; the mass ratio of the composite epoxy resin to the curing agent is 1:0.25-0.8; The composite epoxy resin comprises a difunctional epoxy resin and a tetrafunctional epoxy resin; the mass ratio of the difunctional epoxy resin to the tetrafunctional epoxy resin is 22.5-30:67.5-70; The epoxy value of the bifunctional epoxy resin is 0.44-0.56 mol / 100 g; the epoxy value of the tetrafunctional epoxy resin is 0.75-0.83 mol / 100 g.

4. The epoxy resin according to claim 3, characterized in that: The bifunctional epoxy resin is bisphenol A epoxy resin; the tetrafunctional epoxy resin is tetrafunctional glycidylamine epoxy resin.

5. The epoxy resin according to claim 4, characterized in that: The bisphenol A type epoxy resin is bisphenol A diglycidyl ether; the tetrafunctional glycidylamine epoxy resin is N,N,N',N'-tetracyclyl-4,4'-diaminodiphenylmethane.

6. The epoxy resin according to claim 3, characterized in that: The curing agent is an amine curing agent.

7. The epoxy resin according to any one of claims 3 to 6, characterized in that The molar ratio of the total epoxy groups in the composite epoxy resin to the active hydrogen in the curing agent is 1:0.8-1.

4.

8. The method for preparing the epoxy resin according to any one of claims 3 to 7, characterized in that: The following steps are involved: The composite epoxy resin and the curing agent are mixed, and defoaming and curing are performed in sequence to obtain the epoxy resin.

9. The preparation method according to claim 8, characterized in that: The curing comprises sequentially performing a first curing, a second curing and a third curing; The first curing temperature is 135-160°C and the time is 120-240 minutes; The second curing temperature is 155-180°C and the time is 120-240 minutes; The temperature of the third curing is 180-200° C., and the time is 120-300 minutes.

10. Use of the epoxy resin according to any one of claims 3 to 7 or the epoxy resin prepared by the preparation method according to any one of claims 8 or 9 as a structural part of an aircraft, a car or a tire.

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