A hydroxycarboxylic acid and ɛ-caprolactone co-modified epoxy resin and preparation method thereof

Abstract

The present application provides an epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone, and a preparation method thereof. The method comprises the following steps: S1: reacting an epoxy compound with a hydroxycarboxylic acid compound in the presence of a first catalyst to obtain a hydroxycarboxylate compound; S2: reacting the hydroxycarboxylate compound with ɛ-caprolactone in the presence of a second catalyst to obtain an epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone. Through these two-step reactions, the present application introduces a controllable number of flexible aliphatic polyester segments into the epoxy resin molecular backbone while retaining the overall stability of the main chain structure, thereby effectively regulating the flexibility of the epoxy resin, effectively improving its flexibility and imparting good weather resistance.

Description

Technical Field

[0001] The present application relates to the technical field of epoxy resins, and in particular to an epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone and a preparation method thereof. Background Art

[0002] Epoxy resins are an important class of thermosetting resin materials, widely used in adhesives, coatings, electronic packaging, and composite materials. They are widely used for their excellent mechanical properties, adhesion, electrical insulation, and chemical resistance. However, traditional epoxy resins form a highly cross-linked three-dimensional structure after curing. This results in strong overall rigidity but poor toughness, making them prone to brittle failure under stress or thermal shock, limiting their application in applications requiring high reliability.

[0003] To enhance toughness, various epoxy resin modification methods have been developed, including the introduction of rubber-like elastomers, silicone-based flexible segments, and chemical modification with low-molecular-weight aliphatic monomers. While silicone-based modification systems can impart a certain degree of flexibility, their poor compatibility with the primary epoxy often leads to phase separation and significant fluctuations in mechanical properties. While the introduction of aliphatic structures can improve flexibility, improper structural control can lead to problems such as difficulty controlling molecular weight and unadjustable flexibility.

[0004] For example, CN119875300A discloses a method for modifying epoxy resin by hydroxy hyperbranched polymer, by introducing a hyperbranched polymer with a highly branched structure and polyhydroxy functional groups in an epoxy system, effectively improving the elongation at break and the flexural strength of the modified material, while improving toughness, maintaining good mechanical properties. However, this scheme mainly adopts a pre-synthesized hyperbranched polymer as an additional toughening component, and there are problems such as poor structural controllability, uneven segment distribution or limited flexibility adjustment ability to a certain extent. In addition, current common aliphatic structure modification methods often have low reaction site utilization, imprecise chain length regulation, and even poor hydrolysis resistance and weatherability during flexible introduction.

[0005] Therefore, how to develop a modified epoxy resin that can effectively improve the toughness of epoxy resin, has strong toughness adjustment ability, and has good weather resistance and hydrolysis resistance is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] The present application provides an epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone and a preparation method thereof. The method introduces an ester structure by reacting an epoxy group with a carboxyl group while retaining a polymerizable hydroxyl site, and further grafts a polycaprolactone flexible chain segment to construct a modified structure with controllable number and length of flexible chain segments. While improving the flexibility of the epoxy resin material, it also imparts good structural controllability, compatibility and environmental stability, making it suitable for toughening applications in flexible adhesives, structural composites, weather-resistant coatings and other fields.

[0007] In a first aspect, the present application provides a method for preparing an epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone, comprising the following steps:

[0008] S1: reacting an epoxy compound with a hydroxycarboxylic acid compound under the condition of a first catalyst, so that the epoxy group in the epoxy compound is ring-opened and reacts with the carboxyl group in the hydroxycarboxylic acid compound to obtain a hydroxycarboxylate compound;

[0009] S2: reacting the hydroxycarboxylic acid ester compound with ɛ-caprolactone in the presence of a second catalyst, so that the ɛ-caprolactone is ring-opened and chain-extended at the hydroxyl end of the hydroxycarboxylic acid ester compound, and grafting a poly-ɛ-caprolactone chain segment onto the hydroxycarboxylic acid ester compound to obtain an epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone.

[0010] According to the present application, through the above two-step reaction, a controllable number of flexible aliphatic polyester chain segments can be introduced into the epoxy resin molecular skeleton while retaining the overall stability of the main chain structure, thereby achieving effective regulation of the flexibility of the epoxy resin, effectively improving its flexibility and having good weather resistance.

[0011] Specifically, the above two-step synthesis pathway is as shown in FIG. Figure 1 As shown, in the first step, a hydroxycarboxylic acid compound reacts with an epoxy compound, causing the epoxy group to ring-open to form an ester bond and simultaneously introducing new hydroxyl sites, forming an intermediate backbone with an "ester structure + polyhydroxyl" structure. In the second step, ɛ-caprolactone is introduced, using the hydroxyl groups in the intermediate molecule as initiation sites for ring-opening polymerization, forming polycaprolactone flexible segments, which are then grafted onto the intermediate molecule via ester bonds. The resulting co-modified epoxy resin features controllable flexible segments, with adjustable polymerization length and grafting quantity. These segments are chemically bonded into the molecular structure, avoiding the phase separation problem common in physical blends and enhancing the inter-segment deformation synergy, achieving stable synergy between the flexible segments and the rigid backbone at the molecular level.

[0012] While improving toughness, the epoxy resin provided by this application also has excellent weather resistance. The grafted polycaprolactone segment itself has high hydrophobicity and UV stability. Its molecular structure does not contain active groups that are easily aged, such as aromatic amines, allyl groups or polyether bonds. The structure is mainly composed of saturated fatty chains and ester bonds, and the overall degradation sensitivity is low. In addition, the ester bond is mainly located in the branch segment and forms a block structure with the alkylene segment. The structure presents the characteristics of large steric hindrance and discontinuous exposure, which makes it difficult to form a continuous hydrolysis path. At the same time, the hydroxyl site can further react and cross-link with the anhydride curing agent during the subsequent curing process to form a denser three-dimensional cross-linked structure, further enhancing the shielding ability against moisture and oxygen, thereby improving the long-term stability of the material in complex environments such as humidity, hot water, and ultraviolet light.

[0013] In summary, through the above reaction path, the present application realizes the controllable design of the introduction method, distribution position and chain length structure of the flexible chain segment in the epoxy resin modification process, and can obtain a modified epoxy resin with good flexibility and weather resistance, which is suitable for composite materials and bonding application scenarios that need to meet both flexible deformation and environmental reliability.

[0014] In some embodiments, in step S1, the molar ratio of the epoxy group in the epoxy compound to the carboxyl group in the hydroxycarboxylic acid compound is 1:(0.5-1).

[0015] In some of the aforementioned embodiments, controlling the epoxy-to-carboxyl molar ratio within the range of 1:0.5-1 facilitates achieving a good structural balance between flexibility control and subsequent curing performance. Within this molar ratio range, a suitable hydroxyl density is achieved through an appropriate reaction ratio, providing ample starting points for subsequent grafting of polycaprolactone segments. Controlling the reaction conversion rate also allows for the retention of a moderate number of epoxy groups, reserving active sites for cross-linking reactions with anhydrides or other curing agents.

[0016] When the molar ratio is close to 1:1, the epoxy groups are almost all consumed by the carboxyl groups, resulting in a high-density hydroxyl group and a large number of polycaprolactone chain segments grafted, which can significantly improve the flexibility and impact resistance of the system; when the molar ratio is appropriately higher than 1:1, some epoxy groups do not participate in the esterification reaction and can subsequently form a dense cross-linked structure with anhydride or other curing agents, thereby enhancing the mechanical stability and thermal aging properties of the material; when the molar ratio is higher than 1:0.5, the content of epoxy groups that do not participate in the esterification reaction is too high, which may lead to a decrease in the flexibility of the epoxy resin.

[0017] Therefore, limiting the molar ratio to the range of 1: (0.5~1) can make the modified epoxy resin have a suitable grafting density to obtain flexible modification, which can better improve the flexibility and weather resistance of the epoxy resin material.

[0018] In some embodiments, the molar ratio of the total molar amount of carboxyl groups and hydroxyl groups in the hydroxycarboxylic acid compound to ɛ-caprolactone is 1:(1-2).

[0019] In some of the above embodiments, by adjusting the total molar ratio of carboxyl and hydroxyl groups in the hydroxycarboxylic acid compound to the molar ratio of ɛ-caprolactone, the length of the polycaprolactone flexible segment can be effectively controlled. Figure 1 It can be seen that when hydroxycarboxylic acid compounds react with epoxy compounds, 1 mol of carboxyl groups reacts with 1 mol of epoxy groups to obtain 1 mol of ester bonds and 1 mol of hydroxyl groups. Therefore, the theoretical molar amount of hydroxyl groups in the structure of hydroxycarboxylic acid ester compounds is the total molar amount of carboxyl groups and hydroxyl groups in hydroxycarboxylic acid compounds. The hydroxyl groups on the hydroxycarboxylic acid ester compounds can act as polymerization initiation ends to undergo ring-opening polymerization with ɛ-caprolactone. The length of the grafted polycaprolactone chain segment mainly depends on the feed ratio of ɛ-caprolactone.

[0020] Keeping this molar ratio within the range of 1:(1-2) allows for the construction of flexible aliphatic segments of moderate length within the molecular structure, achieving comprehensive optimization of the material's flexibility and structural stability. When the ɛ-caprolactone feed ratio is relatively low, the grafted segments are short, which improves the system's dimensional stability, but the improvement in flexibility is limited. Increasing the ɛ-caprolactone feed ratio to 1:2 significantly increases the flexible segments, significantly enhancing impact resistance. However, excessively long segments can lead to increased chain entanglement, increased viscosity, and even localized phase inhomogeneities after curing.

[0021] Therefore, controlling the molar ratio within the range of 1:(1~2) can not only ensure that the flexible segments contribute to toughness while maintaining a uniform distribution of segment lengths, but also enable the epoxy resin material to better balance flexibility and weather resistance.

[0022] In some embodiments, in step S1, the epoxy compound includes at least one of a bisphenol epoxy resin, a novolac epoxy resin, an aliphatic epoxy resin, and an alicyclic epoxy resin. Based on the above embodiments, when a bisphenol epoxy resin is used as the raw material, its regular molecular structure and clear distribution of epoxy groups facilitate control of reaction sites and improved modification uniformity. When an alicyclic epoxy, an aliphatic epoxy, or a novolac epoxy resin is used, molecular rigidity and polarity can be adjusted to optimize the match with the hydroxycarboxylic acid compound, thereby constructing a modified epoxy backbone with a more coordinated rigid-flexible structure. Therefore, by selecting different types of epoxy compounds, different structural control pathways and performance adjustment directions can be imparted to the final material.

[0023] In some embodiments, in step S1, the hydroxycarboxylic acid compound includes at least one of α-hydroxyacetic acid, α-hydroxypropionic acid, citric acid, tartaric acid, malic acid, salicylic acid, γ-hydroxybutyric acid, dimethylolpropionic acid, and dimethylolbutyric acid. Based on the above embodiment, the structure and properties of the intermediate can be regulated by selecting hydroxycarboxylic acid compounds with different structural characteristics. The steric hindrance, carboxyl acidity, and hydroxyl number differences brought about by different molecular structures will directly affect the efficiency of the epoxy ring-opening reaction and the number and distribution of generated hydroxyl groups, thereby affecting the subsequent grafting density and segment uniformity of the polycaprolactone chain segment, thereby achieving differentiated construction of epoxy resin materials in terms of flexibility, compatibility, and structural balance.

[0024] In some embodiments, in step S1, the reaction conditions include: a temperature of 80-140°C for 2-6 hours, and the first catalyst comprises at least one of triphenylphosphine, tetrabutylammonium bromide, and tetrabutylammonium chloride. Based on the above embodiments, by controlling the reaction temperature within the above range and using a weakly basic catalyst system, the selectivity of the esterification reaction can be effectively improved, the probability of unnecessary side reactions (such as etherification, side hydrolysis, or cross-linking reactions) can be reduced, and the intermediate structure can be made more predictable, which facilitates the uniformity of hydroxyl group distribution and the efficiency of subsequent chain extension, thereby improving the structural stability and performance consistency of the final modified epoxy resin.

[0025] In some embodiments, in step S1, the first catalyst accounts for 0.1% to 3% of the total mass of the epoxy compound and the hydroxycarboxylic acid compound. Based on the above embodiment, by controlling the catalyst dosage within this range, it is possible to maintain reaction activity while suppressing non-selective side reactions or catalyst residue problems caused by excessive catalysis, further improving the reaction controllability and system stability of the epoxy modification process, and ensuring that an intermediate product with good reactivity and adaptability for subsequent expansion is obtained.

[0026] In some embodiments, in step S2, the reaction conditions include: reacting at 90-140° C. for 4-12 hours, and the second catalyst includes at least one of stannous octoate, stannous oxide, dibutyltin dilaurate, and dioctyltin dilaurate. Based on the above embodiment, the chain extension reaction is carried out under the above conditions, which can achieve steady-state growth of polycaprolactone chain segments and avoid uneven chain length, termination reaction, or side reaction generation due to excessively high temperature or insufficient reaction time; tin-based catalysts such as stannous octoate and dibutyltin dilaurate are mature ring-opening polymerization initiation systems with high catalytic efficiency and strong selectivity for hydroxyl initiators. They can significantly improve the initiation rate and polymerization control accuracy of ɛ-caprolactone at the hydroxyl site, avoid unnecessary side chain formation or structural defects while maintaining reaction activity, thereby improving the structural stability and performance consistency of the final modified epoxy resin.

[0027] In some embodiments, in step S2, the second catalyst comprises 0.05% to 0.3% of the total mass of the hydroxycarboxylate compound and ɛ-caprolactone. Based on the above embodiments, by controlling the catalyst addition amount within this range, chain extension efficiency can be maintained while avoiding catalyst residue issues or rate runaway caused by excess catalyst, further improving the reaction controllability and system stability of the epoxy modification process, and ensuring the production of an intermediate product with good reactivity and compatibility for subsequent expansion.

[0028] In a second aspect, the present application provides an epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone, which is prepared according to the method of any embodiment of the first aspect.

[0029] According to the present application, the epoxy resin is prepared according to the method of any embodiment of the first aspect, and therefore has the beneficial effects of the first aspect.

[0030] In a third aspect, the present application provides an epoxy resin composition comprising the following raw materials in parts by mass: 50 parts of a first epoxy resin, 20 to 40 parts of a second epoxy resin, and 40 to 70 parts of an anhydride curing agent, wherein the first epoxy resin comprises at least one of a bisphenol epoxy resin, a novolac epoxy resin, and an alicyclic epoxy resin, and the second epoxy resin is an epoxy resin according to any embodiment of the second aspect.

[0031] According to the present application, the epoxy resin composition is constructed into a blend system having both a rigid skeleton and a flexible segment through a synergistic combination of the first epoxy resin and the second epoxy resin, wherein the first epoxy resin is used as the main cross-linked skeleton source to give the system good mechanical strength, thermal stability and curing density, while the second epoxy resin introduces a controllably grafted aliphatic flexible segment, which effectively alleviates stress concentration during the curing process and improves the deformation capacity and fracture toughness of the material. Further, an anhydride curing agent is used to form a three-dimensional cross-linked network structure, which not only uniformly embeds the flexible segment in the main system, but also retains the structural integrity and heat resistance under high cross-linking density. This combined structure can take into account both rigidity enhancement and flexible adjustment, while maintaining excellent dimensional stability and environmental adaptability while improving impact strength, and is suitable for a variety of application scenarios requiring toughness and stability, such as structural bonding, electronic packaging, and composite prepregs.

[0032] In some embodiments, the epoxy resin composition further includes 5 to 15 parts of isocyanate-terminated polyurethane prepolymer; the isocyanate-terminated polyurethane prepolymer is obtained by reacting the following raw materials in parts by mass: 50 parts of polyester diol and 15 to 30 parts of diisocyanate.

[0033] In some of the above embodiments, the introduction of isocyanate-terminated polyurethane prepolymers into the epoxy resin composition can further enhance the flexibility and interfacial synergy of the system, forming a dual flexibility adjustment mechanism. The isocyanate end groups in the prepolymer can react with the residual hydroxyl groups in the second epoxy resin or the active groups in the anhydride curing system, thereby being embedded in the overall cross-linked network and participating in the formation of "flexible bridge chains", so that the flexible segments are chemically connected to the main system; the synergistic effect of this structure can effectively alleviate the cross-linking stress concentration and enhance the consistency and energy absorption capacity of the stress transfer path. When co-existing with the grafted polycaprolactone segments in the second epoxy resin, the two can construct a multi-level flexibility adjustment structure, in which polycaprolactone is responsible for introducing intramolecular flexibility and the polyurethane prepolymer provides an intermolecular flexible connecting bridge. The two together enhance the impact strength of the material and significantly improve the overall flexibility of the system. Therefore, the introduction of isocyanate-terminated polyurethane prepolymers into the epoxy resin composition system can further improve the flexibility of the cured epoxy resin in coordination with the second epoxy resin.

[0034] The prepolymer utilizes a polyester diol as a flexible backbone and diisocyanate as a capping structure. By controlling the functional group ratio, the terminal isocyanate groups are retained, allowing for subsequent reaction with the active hydrogen source in the epoxy resin or anhydride curing system. Compared to polyether diols, polyester diols possess higher polarity and hydrophobicity, providing excellent polarity matching and compatibility with the grafted polycaprolactone segments in the second epoxy resin. They can synergistically form a polyester-like phase, thereby improving the overall structural uniformity of the system and the consistency of the flexible segment distribution.

[0035] In addition, compared with polyether prepolymers, polyester prepolymers have regular chain segment distribution, high chain flexibility, and do not contain ether bond structures that are easily oxidized or yellowed. While imparting flexible chain segments, they can also maintain good thermal stability and weather resistance. Their blocked isocyanate groups have moderate reactivity and can effectively participate in cross-linking reactions with residual hydroxyl groups or acid anhydrides during the subsequent thermal curing process to form a structurally controllable flexible bridge chain structure, further enhancing the deformation buffering capacity of the overall material.

[0036] Therefore, the blocked prepolymer prepared by selecting polyester diol and diisocyanate as raw materials can not only provide compatibility synergy with the polycaprolactone chain segments, but also participate in the construction of the cross-linking network in the subsequent reaction, realize the effective embedding of the flexible chain segments, and further improve the flexibility of the cured epoxy resin.

[0037] In some embodiments, the second epoxy resin includes a bisphenol epoxy resin co-modified by hydroxycarboxylic acid and ɛ-caprolactone, and an aliphatic epoxy resin co-modified by dihydroxycarboxylic acid and ɛ-caprolactone; the mass ratio of the bisphenol epoxy resin co-modified by hydroxycarboxylic acid and ɛ-caprolactone to the aliphatic epoxy resin co-modified by dihydroxycarboxylic acid and ɛ-caprolactone is 1:0.4~0.6.

[0038] In some of the above embodiments, the inventors found that the structural differences and modification methods of different types of epoxy resins can construct a more complex and functionally complementary molecular network, and the resulting cured epoxy resin material has better flexibility and weather resistance.

[0039] Furthermore, bisphenol-type epoxy resins have a regular rigid main chain structure and clearly oriented epoxy functionality. After modification with hydroxycarboxylic acid + ɛ-caprolactone, they still maintain a high crosslinking density and mechanical support properties, and are the "rigid components" that provide strength and structural skeleton in the system; aliphatic epoxy resins (such as polypropylene glycol diglycidyl ether) have flexible main chains and rich ether bond structures. After co-modification with dihydroxycarboxylic acid and ɛ-caprolactone, they can form soft chain segments with higher grafting density and free hydroxyl groups, giving the system good flexibility and interfacial buffering capacity; dihydroxycarboxylic acids (such as dihydroxymethylbutyric acid) have a higher hydroxyl / carboxyl ratio than conventional hydroxycarboxylic acids, which is beneficial for providing more polycaprolactone grafting points and free hydroxyl sites, promoting esterification grafting efficiency and subsequent crosslinking density adjustment.

[0040] The synergistic use of the above two modified epoxy resins can construct a rigid-flexible co-embedded network structure at the microscopic level. The flexible aliphatic chain segments play the role of energy buffering and stress transfer between the rigid skeletons, while improving the deformation recovery ability and durability of the material; at the same time, the molecular main chains from different parent materials can enhance the flexibility of compatibility adjustment and reduce stress concentration and the formation of internal defects.

[0041] The mass ratio is controlled within the range of 1:0.4-0.6, ensuring the integrity of the network dominated by the bisphenol-based co-modified epoxy resin while providing an appropriate amount of flexible segment compensation to balance mechanical strength and flexibility. Experimental results also show that this composite system performs excellently in terms of impact strength and retention of heat and humidity aging resistance, surpassing the performance of either type of co-modified epoxy resin alone or any combination of any two other types of co-modified epoxy resins.

[0042] In some embodiments, the anhydride curing agent includes at least one of methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and pyromellitic anhydride. Based on the above embodiments, these anhydride curing agents have high reaction selectivity and structural rigidity, and can efficiently react with the epoxy groups in the first epoxy resin and the residual hydroxyl groups or incompletely esterified sites in the second epoxy resin, forming a dense and uniform three-dimensional cross-linked structure.

[0043] In some embodiments, the polyester diol includes at least one of polycaprolactone diol-1000, polycaprolactone diol-2000, polybutylene adipate diol-1000, and polybutylene adipate diol-2000. Based on the above embodiments, these polyester diols have regular molecular segments and high flexibility, and their molecular structures have good polarity matching with the polycaprolactone structure in the co-modified epoxy. This can further improve the compatibility and synergistic softening effect of the polyurethane prepolymer and the overall network, avoid unstable factors such as phase separation or segment migration, and enhance the flexibility of the cross-linked structure.

[0044] In some embodiments, the diisocyanate comprises at least one of isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate. Based on the above embodiments, the diisocyanate can react with the polyester diol to form a terminal isocyanate structure, which can further form a flexible bridge chain connected by chemical bonds in a system coexisting with an epoxy or anhydride component.

[0045] In some embodiments, the epoxy resin composition further includes 300-800 parts of a diluent, including at least one of methyl formate, ethyl formate, methyl acetate, ethyl acetate, and isopropyl alcohol. Based on the above embodiments, the introduction of a volatile, neutral-polarity solvent as a diluent helps reduce the initial viscosity of the system, improving the workability and dispersibility of the composition. Furthermore, the selected diluents are all volatile, do not participate in side reactions, and can be substantially removed before curing, without affecting crosslinking efficiency or structural density.

[0046] In some embodiments, the epoxy resin composition further includes 10 to 80 parts of a filler, wherein the filler comprises at least one of talc, quartz powder, bentonite, titanium dioxide, white carbon black, and mica powder. Based on the above embodiments, the appropriate amount of inorganic filler can enhance the material's dimensional stability, thermal conductivity, or electrical insulation, and can adjust the material's coefficient of expansion or dielectric properties.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] 1. Through the two-step reaction of esterification and chain extension, flexible polyester segments with controllable quantity and length are introduced to achieve precise control of the flexibility of epoxy resin;

[0049] 2. The flexible chain segments in the co-modified epoxy resin are fixed by chemical grafting and evenly distributed, thus avoiding phase separation and improving the structural stability and consistency of the material;

[0050] 3. The co-modified epoxy resin does not contain aging-prone groups, the ester bonds are discretely distributed, and the system has excellent weather resistance;

[0051] 4. The co-modified epoxy resin can work together with curing components such as anhydride and isocyanate-terminated polyurethane prepolymer to construct a flexible cross-linked network with both toughness and strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0053] Figure 1 The synthetic route diagram of the epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone in this application;

[0054] Wherein, n, m, p and h are natural numbers, m+p=h>0, R1 is the residue of a hydroxycarboxylic acid compound, R2 is the residue of an epoxy compound, n represents the number of epoxy groups that have not been modified with the hydroxycarboxylic acid compound, and n may be 0;

[0055] The synthetic route diagram is only a schematic diagram of the modification reaction of epoxy compounds, illustrating the reaction process of the reactive groups during the modification process. Therefore, only the reaction of a single epoxy group in the epoxy compound with the hydroxycarboxylic acid compound and ɛ-caprolactone is shown. The other epoxy groups in the epoxy compound can also undergo the same reaction. The number of epoxy groups in the epoxy compound that react can be controlled by adjusting the molar ratio of the epoxy group in the epoxy compound to the carboxyl group in the hydroxycarboxylic acid compound. DETAILED DESCRIPTION

[0056] The various embodiments or implementation schemes in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments.

[0057] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0059] In the description of this specification, unless otherwise specified, "parts" refer to "parts by mass".

[0060] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0061] Example 1-1

[0062] Preparation of epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone:

[0063] (1) Add 380 g of bisphenol A epoxy resin YD-128 (epoxy content of about 2 mol) and 4.56 g of triphenylphosphine catalyst to a 1 L four-necked flask, then heat to 90 ° C. Slowly add 76 g (1 mol) of α-hydroxyacetic acid at 90 ° C for 1 hour, ensuring that the exothermic temperature does not exceed 110 ° C. After the addition is complete, heat to 110 ° C and react at this temperature for 3 hours to obtain a polyhydroxy carboxylate epoxy resin;

[0064] (2) The first step reactants were cooled to 60°C, and then 228.3 g (2 mol) of ɛ-caprolactone and 0.7 g of stannous octoate as a catalyst were added. The temperature was then raised to 120°C and reacted for 8 h to obtain the final product, i.e., the co-modified epoxy resin A of hydroxyacetic acid and ɛ-caprolactone.

[0065] Example 1-2

[0066] Preparation of epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone:

[0067] (1) Add 380 g of bisphenol A epoxy resin YD-128 (epoxy content of about 2 mol) and 4.94 g of tetrabutylammonium bromide as catalyst to a 1 L four-necked flask, then heat to 90 °C. Slowly add 114 g (1.5 mol) of α-hydroxyacetic acid at 90 °C for 1.5 h, ensuring that the exothermic temperature does not exceed 110 °C. After the addition is complete, heat to 110 °C and react at this temperature for 4 h to obtain a polyhydroxycarboxylate epoxy resin.

[0068] (2) The first step reactants were cooled to 60°C, and then 342.5 g (3 mol) of ɛ-caprolactone and 0.84 g of stannous octoate as a catalyst were added. The temperature was then raised to 130°C and reacted for 8 h to obtain the final product, i.e., the co-modified epoxy resin B of hydroxyacetic acid and ɛ-caprolactone.

[0069] Examples 1-3

[0070] Preparation of epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone:

[0071] (1) Add 560 g of hydrogenated bisphenol A epoxy resin KST-1701 (epoxy content of about 2 mol) and 6.30 g of triphenylphosphine catalyst into a 1 L four-necked flask, then heat to 90 ° C, slowly add 76 g (1 mol) of α-hydroxyacetic acid at 90 ° C for 1 hour, ensuring that the exothermic temperature does not exceed 110 ° C. After the addition is complete, heat to 115 ° C and react at this temperature for 4 hours to obtain a polyhydroxy carboxylate epoxy resin;

[0072] (2) The first step reactants were cooled to 60°C, and then 228.3 g (2 mol) of ɛ-caprolactone and 0.87 g of stannous octoate as a catalyst were added. The temperature was then raised to 130°C and reacted for 9 h to obtain the final product, i.e., the co-modified epoxy resin C of hydroxyacetic acid and ɛ-caprolactone.

[0073] Examples 1-4

[0074] Preparation of epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone:

[0075] (1) Add 560 g of hydrogenated bisphenol A epoxy resin KST-1701 (epoxy content of about 2 mol) and 6.90 g of tetrabutylammonium bromide as catalyst to a 1.5 L four-necked flask, then heat to 90 °C. Slowly add 136.2 g (1.5 mol) of α-hydroxypropionic acid at 90 °C for 1.5 h, ensuring that the exothermic temperature does not exceed 110 °C. After the addition is complete, heat to 115 °C and react at this temperature for 4 h to obtain a polyhydroxycarboxylate epoxy resin.

[0076] (2) The first step reactants were cooled to 60°C, and then 342.5 g (3 mol) of ɛ-caprolactone and 1.0 g of stannous octoate as a catalyst were added. The temperature was then raised to 130°C and reacted for 9 h to obtain the final product, i.e., the co-modified epoxy resin D of hydroxypropionic acid and ɛ-caprolactone.

[0077] Examples 1-5

[0078] Preparation of epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone:

[0079] (1) Add 667 g of polypropylene glycol diglycidyl ether XY-207A (epoxy content of about 2 mol) and 8.0 g of triphenylphosphine into a 1.5 L four-necked flask, then heat to 90°C. Slowly add 136.2 g (1.5 mol) of α-hydroxypropionic acid dropwise at 90°C for 1.5 hours, ensuring that the exothermic temperature rise does not exceed 110°C. After the addition is complete, heat to 115°C and react at this temperature for 4 hours to obtain a polyhydroxycarboxylate epoxy resin.

[0080] (2) The first step reactants were cooled to 60°C, and then 456.8 g (4 mol) of ɛ-caprolactone and 1.2 g of stannous octoate as a catalyst were added. The temperature was then raised to 130°C and reacted for 9 h to obtain the final product, i.e., the co-modified epoxy resin E of hydroxypropionic acid and ɛ-caprolactone.

[0081] Examples 1-6

[0082] Preparation of epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone:

[0083] (1) Add 380 g of bisphenol A epoxy resin YD-128 (epoxy content of about 2 mol) and 5.1 g of triphenylphosphine into a 1.5 L four-necked flask, then heat to 90°C. Slowly add 134.2 g (1.0 mol) of 2,2-dimethylolpropionic acid at 90°C for 1.0 h, ensuring that the exothermic temperature does not exceed 130°C. After the addition is complete, heat to 130°C and react at this temperature for 4 h to obtain a polyhydroxycarboxylate epoxy resin.

[0084] (2) The first step reactants were cooled to 60°C, and then 456.8 g (4 mol) of ɛ-caprolactone and 1.0 g of stannous octoate as a catalyst were added. The temperature was then raised to 120°C and reacted for 10 h to obtain the final product, i.e., the co-modified epoxy resin F of 2,2-dihydroxymethylpropionic acid and ɛ-caprolactone.

[0085] Examples 1-7

[0086] Preparation of epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone:

[0087] (1) Add 667 g of polypropylene glycol diglycidyl ether XY-207A (epoxy content of about 2 mol) and 8.1 g of triphenylphosphine into a 1.5 L four-necked flask, then heat to 90°C. Slowly add 148.2 g (1.0 mol) of 2,2-dihydroxymethylbutyric acid at 90°C for 1.0 h, ensuring that the exothermic temperature does not exceed 110°C. After the addition is complete, heat to 120°C and react at this temperature for 4 h to obtain a polyhydroxycarboxylate epoxy resin.

[0088] (2) The first step reactants were cooled to 60°C, and then 456.8 g (4 mol) of ɛ-caprolactone and 1.3 g of stannous octoate as a catalyst were added. The temperature was then raised to 120°C and reacted for 10 h to obtain the final product, i.e., the co-modified epoxy resin G of 2,2-dihydroxymethylbutyric acid and ɛ-caprolactone.

[0089] Preparation Example 2-1

[0090] Preparation of isocyanate-terminated polyurethane prepolymer:

[0091] 50 g of polycaprolactone diol-1000 was added to the reactor, vacuum dehydrated at 100° C. for 1 h, cooled to 85° C., 22.23 g of isophorone diisocyanate was added to the reactor, and stirred for reaction for 2.5 h to obtain isocyanate-terminated polyurethane prepolymer A.

[0092] Preparation Example 2-2

[0093] Preparation of isocyanate-terminated polyurethane prepolymer:

[0094] 50 g of polytetrahydrofuran-1000 was added to the reactor, vacuum dehydrated at 100° C. for 1 h, cooled to 85° C., 22.23 g of isophorone diisocyanate was added to the reactor, and stirred for reaction for 2.5 h to obtain isocyanate-terminated polyurethane prepolymer B.

[0095] Example 2-1

[0096] Preparation of epoxy resin composition:

[0097] 50 g of bisphenol A epoxy resin YD-128 and 30 g of co-modified epoxy resin A were dispersed in 600 mL of ethyl acetate, 50 g of hexahydrophthalic anhydride was added at a temperature not exceeding 70° C., and after mixing evenly, 10 g of isocyanate-terminated polyurethane prepolymer A and 50 g of quartz powder with an average particle size of 1 μm were added. After uniform dispersion, the mixture was decompressed and degassed to obtain an epoxy resin composition.

[0098] Example 2-2

[0099] Preparation of epoxy resin composition:

[0100] The process is substantially the same as Example 2-1, except that the co-modified epoxy resin B is used instead of the co-modified epoxy resin A.

[0101] Example 2-3

[0102] Preparation of epoxy resin composition:

[0103] The process is substantially the same as Example 2-1, except that the co-modified epoxy resin C is used instead of the co-modified epoxy resin A.

[0104] Examples 2-4

[0105] Preparation of epoxy resin composition:

[0106] The process is substantially the same as Example 2-1, except that the co-modified epoxy resin D is used instead of the co-modified epoxy resin A.

[0107] Examples 2-5

[0108] Preparation of epoxy resin composition:

[0109] The process is substantially the same as Example 2-1, except that the co-modified epoxy resin E is used instead of the co-modified epoxy resin A.

[0110] Examples 2-6

[0111] Preparation of epoxy resin composition:

[0112] The process is substantially the same as Example 2-1, except that the co-modified epoxy resin F is used instead of the co-modified epoxy resin A.

[0113] Examples 2-7

[0114] Preparation of epoxy resin composition:

[0115] The process is substantially the same as Example 2-1, except that the co-modified epoxy resin G is used instead of the co-modified epoxy resin A.

[0116] Examples 2-8

[0117] Preparation of epoxy resin composition:

[0118] 50 g of bisphenol A epoxy resin YD-128 and 30 g of co-modified epoxy resin A were dispersed in 600 mL of ethyl acetate, 60 g of hexahydrophthalic anhydride was added at a temperature not exceeding 70° C., and after uniform mixing, 50 g of quartz powder with an average particle size of 1 μm was added, and after uniform dispersion, the mixture was decompressed and degassed to obtain an epoxy resin composition.

[0119] Examples 2-9

[0120] Preparation of epoxy resin composition:

[0121] The process is substantially the same as Example 2-1, except that isocyanate-terminated polyurethane prepolymer B is used instead of isocyanate-terminated polyurethane prepolymer A.

[0122] Example 2-10

[0123] Preparation of epoxy resin composition:

[0124] The method is substantially the same as Example 2-1, except that 20 g of co-modified epoxy resin A and 10 g of co-modified resin C are used instead of 30 g of co-modified epoxy resin A.

[0125] Example 2-11

[0126] Preparation of epoxy resin composition:

[0127] The method is substantially the same as Example 2-1, except that 20 g of co-modified epoxy resin A and 10 g of co-modified resin E are used instead of 30 g of co-modified epoxy resin A.

[0128] Example 2-12

[0129] Preparation of epoxy resin composition:

[0130] The method is substantially the same as Example 2-1, except that 20 g of co-modified epoxy resin A and 10 g of co-modified resin G are used instead of 30 g of co-modified epoxy resin A.

[0131] Comparative Example 2-1

[0132] Preparation of epoxy resin composition:

[0133] 80 g of bisphenol A epoxy resin YD-128 was dispersed in 600 mL of ethyl acetate, 50 g of hexahydrophthalic anhydride was added at a temperature not exceeding 70° C., and after mixing evenly, 10 g of isocyanate-terminated polyurethane prepolymer A and 50 g of quartz powder with an average particle size of 1 μm were added. After uniform dispersion, the mixture was decompressed and degassed to obtain an epoxy resin composition.

[0134] Comparative Example 2-2

[0135] Preparation of epoxy resin composition:

[0136] 50 g of bisphenol A epoxy resin YD-128 and 30 g of co-modified epoxy resin A were dispersed in 600 mL of ethyl acetate, 40 g of p-phenylenediamine was added at a temperature not exceeding 70° C., and after mixing evenly, 10 g of isocyanate-terminated polyurethane prepolymer A and 50 g of quartz powder with an average particle size of 1 μm were added. After uniform dispersion, the mixture was decompressed and degassed to obtain an epoxy resin composition.

[0137] Test section

[0138] The epoxy resin compositions obtained in the examples and comparative examples were cured to obtain cured epoxy resin materials. The curing conditions were: pre-curing at 100° C. for 2 h, and then pre-curing at 150° C. for 3 h. The materials were cut into test strips for later use.

[0139] The cured epoxy resin material is subjected to an unnotched impact test using a simple supported beam impact tester to test its impact strength. k1 (kJ / m 2 ), the specimen size is 80mm×10mm×4mm, the results are shown in Table 1; the same batch of specimens were soaked in 80℃ hot water for 10d, taken out and dried, and then used a simple supported beam impact tester to perform an unnotched impact test to test its impact strength a k2 (kJ / m 2 ), calculate the impact strength retention rate σ=a k2 / a k1 ×100%, the results are shown in Table 1.

[0140] Table 1

[0141]

[0142] As shown in Table 1, the impact strength and impact strength retention rate of the cured epoxy resin materials obtained in each embodiment are significantly higher than those in each comparative example, indicating that the co-modified epoxy resin provided in the present application can effectively improve the flexibility and weather resistance of the epoxy resin material, and the obtained cured epoxy resin material has good flexibility and weather resistance. Among them, the flexibility adjustment structure is not introduced in Comparative Example 2-1, and its curing system is composed of traditional bisphenol A epoxy resin and acid anhydride. The cross-linked structure has high rigidity, concentrated exposure of ester bonds, and lacks hydrophobic segment shielding and flexible buffering areas, resulting in the material being prone to hydrolysis chain scission and structural brittle cracking during wet heat aging, thereby causing a significant decline in impact strength. Therefore, the flexibility and weather resistance of the cured epoxy resin material obtained are relatively poor; it also illustrates that the use of isocyanate-terminated polyurethane prepolymer alone cannot effectively improve the flexibility and weather resistance of the cured epoxy resin material. Only by combining it with the co-modified epoxy resin material provided in the present application can the flexibility and weather resistance of the cured epoxy resin material be effectively improved.

[0143] Although co-modified epoxy resin was introduced in Comparative Example 2-2, the use of paraphenylenediamine as a curing agent formed a cured network with high hydrophilicity and poor structural stability, and failed to effectively utilize the hydroxyl groups in the co-modified epoxy to form synergistic crosslinks with the anhydride curing agent, resulting in the system being easily water-absorbent and easily degraded under wet heat aging conditions, and the impact strength seriously deteriorated. Therefore, the resulting cured epoxy resin material has poor flexibility and weather resistance.

[0144] According to Examples 2-1 to 2-7, by using different types of epoxy compounds and hydroxycarboxylic acid compounds and controlling the addition amounts of epoxy compounds, hydroxycarboxylic acid compounds and ɛ-caprolactone within a suitable range, the co-modified epoxy resin materials obtained can effectively improve the flexibility and weather resistance of the cured epoxy resin materials.

[0145] According to Examples 2-1, 2-8, and 2-9, it can be seen that whether an isocyanate-terminated polyurethane prepolymer is added to the epoxy resin composition and the structure of the isocyanate-terminated polyurethane prepolymer have a certain influence on the flexibility and weather resistance of the cured epoxy resin material; further adding an isocyanate-terminated polyurethane prepolymer to the epoxy resin composition can synergistically co-modify the epoxy resin material, so that the flexibility and weather resistance of the cured epoxy resin material are better; when the flexible segment in the isocyanate-terminated polyurethane prepolymer is a polyester segment, the synergistic effect with the co-modified epoxy resin material is better, and the resulting cured epoxy resin material has better flexibility and weather resistance.

[0146] Examples 2-1, 2-3, 2-5, 2-7, and 2-10 through 2-12 demonstrate that the introduction of a second, structurally distinct co-modified epoxy resin (e.g., co-modified epoxy resin C, co-modified epoxy resin E, and co-modified epoxy resin G) into co-modified epoxy resin A, while maintaining a reasonable mass ratio between the two, can synergistically construct a rigid-flexible co-embedded microstructure, enhancing the overall performance of the material. The complementary segment configurations between the molecules of the different co-modified resins maintain backbone strength and crosslinking while also introducing more flexible segments and a hydrophilic-hydrophobic structure, which helps disperse stress and mitigate structural damage caused by thermal expansion and contraction. This significantly improves the impact strength retention of the cured material under high-temperature and high-humidity conditions, enhances hydrolysis resistance, and improves flexibility. Compared with a single co-modified structure, the toughness improvement of the compounded system is more stable and the weather resistance retention rate is higher; in particular, when co-modified epoxy resin A and co-modified epoxy resin G are compounded in a certain mass ratio, the resulting cured epoxy resin material has better flexibility and weather resistance.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An epoxy resin composition, characterized in that Including the following raw materials by weight: 50 parts of the first epoxy resin, 20-40 parts of the second epoxy resin, 40-70 parts of an anhydride curing agent; 5-15 parts of an isocyanate-terminated polyurethane prepolymer; The first epoxy resin comprises at least one of bisphenol epoxy resin, novolac epoxy resin and alicyclic epoxy resin. The second epoxy resin includes a bisphenol epoxy resin co-modified by hydroxycarboxylic acid and ɛ-caprolactone, and an aliphatic epoxy resin co-modified by dihydroxycarboxylic acid and ɛ-caprolactone; the mass ratio of the bisphenol epoxy resin co-modified by hydroxycarboxylic acid and ɛ-caprolactone to the aliphatic epoxy resin co-modified by dihydroxycarboxylic acid and ɛ-caprolactone is 1:0.4-0.6; The preparation method of the bisphenol epoxy resin co-modified by hydroxycarboxylic acid and ɛ-caprolactone comprises: M1: reacting a bisphenol epoxy resin with a hydroxycarboxylic acid in the presence of a first catalyst to cause the epoxy group in the epoxy compound to ring-open and react with the carboxyl group in the hydroxycarboxylic acid to obtain a first hydroxycarboxylic acid ester compound; wherein the molar ratio of the epoxy group in the bisphenol epoxy resin to the carboxyl group in the hydroxycarboxylic acid is 1:(0.5-1); and the hydroxycarboxylic acid is at least one of α-hydroxyacetic acid, α-hydroxypropionic acid, citric acid, malic acid, salicylic acid, and γ-hydroxybutyric acid; M2: reacting the first hydroxycarboxylate compound with ɛ-caprolactone in the presence of a second catalyst to cause ring-opening and chain extension of the hydroxyl end of the ɛ-caprolactone in the first hydroxycarboxylate compound, grafting a poly-ɛ-caprolactone chain segment onto the first hydroxycarboxylate compound, and obtaining a bisphenol epoxy resin co-modified with hydroxycarboxylic acid and ɛ-caprolactone; The preparation method of the aliphatic epoxy resin co-modified by dihydroxy carboxylic acid and ɛ-caprolactone comprises: N1: reacting an aliphatic epoxy resin with a dihydroxycarboxylic acid in the presence of a first catalyst to cause the epoxy groups in the epoxy compound to ring-open and react with the carboxyl groups in the dihydroxycarboxylic acid to obtain a second hydroxycarboxylic acid ester compound; wherein the molar ratio of the epoxy groups in the aliphatic epoxy resin to the carboxyl groups in the dihydroxycarboxylic acid is 1:(0.5-1); and the dihydroxycarboxylic acid comprises at least one of tartaric acid, dimethylolpropionic acid, and dimethylolbutanoic acid; N2: reacting a second hydroxycarboxylate compound with ɛ-caprolactone in the presence of a second catalyst to cause ring-opening and chain extension of the hydroxyl end of ɛ-caprolactone in the second hydroxycarboxylate compound, and grafting a poly-ɛ-caprolactone chain segment onto the second hydroxycarboxylate compound to obtain an aliphatic epoxy resin co-modified with dihydroxycarboxylic acid and ɛ-caprolactone.

2. The epoxy resin composition according to claim 1, characterized in that In the preparation method of the bisphenol epoxy resin co-modified by hydroxycarboxylic acid and ɛ-caprolactone, the molar ratio of the total molar amount of carboxyl groups and hydroxyl groups in the hydroxycarboxylic acid to the ɛ-caprolactone is 1:(1-2); In the preparation method of the aliphatic epoxy resin co-modified by dihydroxycarboxylic acid and ɛ-caprolactone, the molar ratio of the total molar amount of carboxyl groups and hydroxyl groups in the dihydroxycarboxylic acid to ɛ-caprolactone is 1:(1~2).

3. The epoxy resin composition according to claim 1, characterized in that Step M1 satisfies at least one of the following conditions: 1) The reaction conditions include: reacting at 80-140° C. for 2-6 hours; the first catalyst includes at least one of triphenylphosphine, tetrabutylammonium bromide, and tetrabutylammonium chloride; 2) The first catalyst accounts for 0.1% to 3% of the total mass of the bisphenol epoxy resin and the hydroxycarboxylic acid.

4. The epoxy resin composition according to claim 1, characterized in that Step N1 satisfies at least one of the following conditions: 1) The reaction conditions include: reacting at 80-140° C. for 2-6 hours; the first catalyst includes at least one of triphenylphosphine, tetrabutylammonium bromide, and tetrabutylammonium chloride; 2) The first catalyst accounts for 0.1% to 3% of the total mass of the aliphatic epoxy resin and the dihydroxycarboxylic acid.

5. The epoxy resin composition according to claim 1, characterized in that Step M2 satisfies at least one of the following conditions: 1) The reaction conditions include: reacting at 90-140° C. for 4-12 hours; the second catalyst includes at least one of stannous octoate, stannous oxide, dibutyltin dilaurate, and dioctyltin dilaurate; 2) The second catalyst accounts for 0.05% to 0.3% of the total mass of the first hydroxycarboxylate compound and ɛ-caprolactone.

6. The epoxy resin composition according to claim 1, characterized in that Step N2 satisfies at least one of the following conditions: 1) The reaction conditions include: reacting at 90-140° C. for 4-12 hours; the second catalyst includes at least one of stannous octoate, stannous oxide, dibutyltin dilaurate, and dioctyltin dilaurate; 2) The second catalyst accounts for 0.05% to 0.3% of the total mass of the second hydroxycarboxylate compound and ɛ-caprolactone.

7. The epoxy resin composition according to claim 1, characterized in that The isocyanate-terminated polyurethane prepolymer is obtained by reacting the following raw materials in parts by mass: 50 parts of polyester diol, 15-30 parts of diisocyanate.

8. The epoxy resin composition according to any one of claims 1 to 7, characterized in that The epoxy resin composition satisfies at least one of the following conditions: 1) The anhydride curing agent includes at least one of methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride and pyromellitic anhydride; 2) the polyester diol comprises at least one of polycaprolactone diol-1000, polycaprolactone diol-2000, polybutylene adipate diol-1000, and polybutylene adipate diol-2000; 3) The diisocyanate includes at least one of isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; 4) further comprising 300 to 800 parts of a diluent, wherein the diluent comprises at least one of methyl formate, ethyl formate, methyl acetate, ethyl acetate, and isopropyl alcohol; 5) The composition further comprises 10 to 80 parts of a filler, wherein the filler comprises at least one of talc powder, quartz powder, bentonite, titanium dioxide, white carbon black and mica powder.

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