End-capped polyurethane flexibilizer, epoxy resin composition and preparation method of epoxy resin composition

Abstract

The invention relates to the field of epoxy resin, in particular to an end-capped polyurethane flexibilizer, an epoxy resin composition and a preparation method of the epoxy resin composition. The end-capped polyurethane toughening agent is prepared by reacting hydroxyl end-capped polyesterimide polyol, polyisocyanate, a chain extender and a sealing agent according to a feeding ratio of (66 to 83): (14 to 20): (0 to 2): (0.5 to 15). After the end-capped polyurethane flexibilizer is applied to an epoxy resin system, the problems of high-temperature-resistant toughness and strength of a chip packaging adhesive can be solved at the same time, so that the corresponding epoxy resin system is suitable for high-integration circuit board packaging at the present stage.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of epoxy resin, more particularly, it relates to an end-capped polyurethane toughening agent, an epoxy resin composition and a preparation method thereof. BACKGROUND

[0002] In the chip packaging application, the chip packaged by the epoxy glue has the effects of insulation, sealing, shock resistance and the like, and plays a protective role for the chip. However, with the development of high-frequency and high-speed integrated circuits towards integration and miniaturization, the traditional epoxy glue cannot be applied to the highly integrated chip packaging due to its poor temperature resistance, poor toughness, easy cracking and the like.

[0003] On the highly integrated circuit board, a large amount of heat is generated during the operation of the chip. With the long-term accumulation of heat, the chip packaging may be cracked, i.e., the packaging material may be aged, brittle, warped and mechanically damaged, and then the chip may be exposed and corroded. Therefore, the chip packaging glue with temperature resistance has emerged in the market.

[0004] In the related art, the temperature resistance of the packaging glue is improved by using a multifunctional resin to increase the crosslinking density. However, it is known to those skilled in the art that the multifunctional resin makes the glue brittle and not tough. Insufficient toughness also affects the packaging, and then leads to packaging cracking, chip damage and even failure.

[0005] Therefore, at present, some enterprises replace the multifunctional resin with an organic silicon modified resin. However, the compatibility between the organic silicon and the epoxy resin is poor, and the interface separation or debonding problem may occur under extreme conditions. The improvement of the toughness of the glue, especially the high-temperature toughness, is very limited, and the strength and modulus are greatly damaged.

[0006] For example, if a conventional toughening technology such as a polyurethane, rubber, fatty acid modified resin is used, the toughness can be effectively increased, but the heat resistance is not significantly improved or has a negative effect. For example, the method of using polytetramethylene ether glycol as a flexible chain and reacting with isocyanate monomer and then using a blocking agent for end-capping can reduce the high-temperature resistance of the epoxy resin material.

[0007] Therefore, how to solve the problem of the high-temperature toughness and strength of the chip packaging glue is a technical problem to be solved by those skilled in the art. In summary, the end-capped polyurethane toughening agent, the epoxy resin composition and the preparation method thereof can be applied to the highly integrated circuit board packaging at present. SUMMARY

[0008] The application provides an end-capped polyurethane toughening agent, an epoxy resin composition and a preparation method thereof. The epoxy resin has excellent high strength and high-temperature toughness without damaging the modulus of the matrix, can ensure long-term reliability of packaging when used for chip packaging glue, enables the chip to work stably for a long time under different working environments and temperature conditions, and improves the service life of the chip.

[0009] In a first aspect, the application provides an end-capped polyurethane toughening agent, which is prepared by reacting a hydroxyl-terminated polyester-imine polyol, a polyisocyanate, a chain extender and a blocking agent in a feeding ratio of (66-83):(14-20):(0-2):(0.5-15).

[0010] The hydroxyl-terminated polyester-imine polyol has the following structural formula: Formula (I); The R has the following structural formula: .

[0011] Preferably, the end-capped polyurethane toughening agent is prepared by the following preparation process:

[0012] 1) In a reaction kettle, the hydroxyl-terminated polyester-imine polyol is dehydrated at 95-110°C under vacuum to a negative pressure of 0.09-0.1 MPa for 1-2 hours with minimum stirring;

[0013] 2) After being cooled to 25-50°C, the polyisocyanate and the catalyst are added, and the reaction is carried out at 50-80°C under a nitrogen atmosphere with stirring for 2-4 hours to obtain an isocyanate-terminated polymer;

[0014] 3) When the NCO content of the polymer is 1.20-6.00%, the chain extender is added to the isocyanate-terminated polymer obtained in 2) under a nitrogen atmosphere, and the reaction is carried out at 50-80°C with stirring for 1-2 hours;

[0015] 4) When the NCO content of the polymer is 1.20-4.50%, the blocking agent and the catalyst are continuously added, and the reaction is carried out at 80-110°C with vigorous stirring for 2-12 hours, the blocking agent is supplemented, and the reaction is continuously carried out for 1-4 hours to obtain the end-capped polyurethane toughening agent. To complete the blocking of the isocyanate, the final product is placed in an oven at 70°C overnight, and the NCO content is 0-0.10%.

[0016] Preferably, the hydroxyl-terminated polyester-imine polyol has a hydroxyl value of 20-120 mg / KOH.

[0017] Preferably, the chain extender is selected from one or more of 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, ethylene glycol, diethylene glycol, 1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol / neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 1,8-octanediol, 2,4-diethyl-1,3-octanediol, trimethyl-1,6-hexanediol, 1,7-heptanediol, 4-propyl-1,8-octanediol, 1,9-nonanediol, hydroquinone dihydroxyethyl ether, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,4-diethyl-1,5-pentanediol, polyoxypropylene polyols having a molecular weight of 200-1000, trimethylolpropane, glycerol.

[0018] Preferably, the blocking agent is selected from one or more of phenol, cresol, dimethylphenol, p-tert-butylphenol, 3-pentadecenylphenol, pyridinol, 2-trifluoroethanol, thiophenol, hexanethiol, dodecyl mercaptan, acetanilide, caprolactam, 2-butanone oxime, 2,2'-diallyl bisphenol A, 4-vinylphenol, p-aminophenol, cardanol, p-acetylamino phenol, p-acetylphenol.

[0019] Preferably, the catalyst is selected from dibutyltin dilaurate (DBTL) or bismuth-III neodecanoate.

[0020] In a second aspect, the present application provides a high-strength, high-temperature-resistant toughened epoxy resin, comprising an epoxy resin and any of the above-mentioned capped polyurethane toughening agents.

[0021] Preferably, the high-strength, high-temperature-resistant toughened epoxy resin is composed of the following components by weight:

[0022] 5-60 parts of any of the above-mentioned capped polyurethane toughening agents;

[0023] 50-100 parts of an epoxy resin; 5-20 parts of a curing agent; 0.01-5.0 parts of an accelerator; 0-10 parts of a functional additive.

[0024] Preferably, the epoxy resin is one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, silicone-modified epoxy resin, phosphoric acid-modified epoxy resin, polyurethane-modified epoxy resin, fatty acid-modified epoxy resin, rubber-modified epoxy resin.

[0025] Preferably, the curing agent is one or more of the following: aliphatic amines, cycloaliphatic amines, dicyandiamides, polyamides, imidazoles, epoxy resin-modified amines, polyether amines, acylhydrazides, diaminodiphenyl sulfones, boron trifluoride amine complexes, organic ureas, acid anhydrides, and thiols.

[0026] Preferably, the accelerator is one or more of the following: fatty amine accelerators, acid anhydride accelerators, polyether amine accelerators, urea accelerators, and imidazole accelerators, mixed in any proportion.

[0027] Preferably, the functional additive is one or more of the following: filler, stabilizer, diluent, defoamer, thixotropic agent, coupling agent, dispersant, etc.

[0028] Thirdly, this application discloses a method for preparing a high-strength, high-temperature resistant toughened epoxy resin, comprising the following steps:

[0029] S1. First, heat the epoxy resin and end-capped polyurethane toughening agent to 60-80℃ and mix them evenly. After cooling to 30-40℃, add the curing agent, accelerator and functional additive in sequence, mix them evenly, and then perform vacuum degassing after ultrasonic vibration treatment to obtain the prepolymer.

[0030] S2. Cast the prepolymer obtained in S1 into a mold, raise the temperature to 100-120℃ and cure for 1-4 hours, continue to raise the temperature to 130-150℃ and cure for 2-5 hours. After curing, cool to room temperature with the furnace and demold to obtain high-strength, high-temperature toughened epoxy resin.

[0031] In summary, this application has the following beneficial effects:

[0032] 1. The end-capped polyurethane toughening agent in this application is synthesized using hydroxyl-capped polyesterimine polyol as the main raw material. The chain length and intermolecular forces of the end-capped polyurethane are controlled by the structure-activity relationship and ratio of isocyanate group and polyesterimine polyol to obtain a suitable phase separation structure, thereby obtaining excellent high temperature resistance and flexibility, which meets the prerequisite for its application in epoxy resin system.

[0033] 2. The end-capped polyurethane toughening agent obtained in this application can significantly achieve high-temperature toughening effect when applied to epoxy resin system. Compared with other toughening agents, this toughening agent can improve the high-temperature resistance and strength of epoxy resin while ensuring the modulus of the resin matrix, so as to meet the application conditions in chip encapsulation adhesive.

[0034] 3. The preparation method of the high-strength, high-temperature toughening epoxy resin in this application is relatively simple. All operations and conditions are easy to achieve, which facilitates the acquisition of stable and uniform products, which is conducive to industrial production. Furthermore, the obtained products can be controlled by process methods. By controlling the mixing and curing processes, the toughening effect can be further achieved. Attached Figure Description

[0035] Figure 1 The infrared spectrum of the hydroxyl-terminated polyesterimine polyol obtained in Preparation Example 1;

[0036] Figure 2 The infrared spectrum of the end-capped polyurethane toughening agent obtained in Example 2. Detailed Implementation

[0037] The following is in conjunction with the appendix Figures 1-2 The preparation examples and embodiments further illustrate this application in detail.

[0038] Unless otherwise specified in Table 1 below, the raw materials and / or equipment used in the preparation examples, embodiments, and tests of this application are all commercially available conventional raw materials and equipment:

[0039] Table 1: List of Raw Materials and Equipment

[0040]

[0041] Preparation Example 1

[0042] A hydroxyl-terminated polyesterimine polyol has the following structural formula: Formula (I); The structural formula of R is: The following preparation steps were used to obtain it:

[0043] Polyol monomers, polyacid monomers, catalysts, TMA and MDA were added to the reactor at room temperature, and the temperature was raised to 220°C during the feeding process, while the column top temperature was controlled at 102°C.

[0044] The polyol monomer is polypropylene glycol 400; the polyacid monomer is adipic acid; and the catalyst is tetrabutyl titanate.

[0045] The feed ratio of the polyol monomer, polyacid monomer, catalyst, TMA and MDA is 60.71:8.08:0.08:20.54:10.59;

[0046] Then, a vacuum is drawn and the vacuum level is gradually increased to evaporate the reaction byproducts under reduced pressure. After holding at this temperature for 2 hours, hydroxyl-terminated polyesterimine polyols can be obtained.

[0047] Its infrared spectrum is as follows Figure 1As shown in the figure, the characteristic absorption peak of hydroxyl-terminated polyesterimine polyols is found at 3471.34 cm⁻¹. -1 The corresponding stretching vibration absorption peak of the hydroxyl group is at 2970.04 cm⁻¹. -1 and 2868.05 cm -1 The corresponding stretching vibration absorption peak for the methyl group is at 1780.96 cm⁻¹. -1 and 1717.04 cm -1 These correspond to the asymmetric and symmetric stretching vibration peaks of the imine ring structure -CO-N-CO-, respectively, at 1692.37 cm⁻¹. -1 The corresponding absorption peak for the stretching vibration of imide C=O is 1514.17 cm⁻¹. -1 The absorption peak corresponding to the stretching vibration of the benzene ring skeleton is at 1365.02 cm⁻¹. -1 The corresponding axial vibration peak of the imide ring is 1216.00 cm⁻¹. -1 The corresponding absorption peak for the CN stretching vibration is at 1093.45 cm⁻¹. -1 The corresponding absorption peak for the stretching vibration of COC on polypropylene glycol is 723.71 cm⁻¹. -1 The absorption peak corresponds to the C=O bending vibration of the imide.

[0048] The presence of the aforementioned characteristic absorption peaks indicates the existence of an imine ring structure, confirming that hydroxyl-terminated polyesterimine polyols can be synthesized through the above process. The hydroxyl value of the aforementioned polyesterimine polyol is 56.8 mgKOH / g, [OH] / [COOH] is 1.39, and the contents of TMA and MDA are 31.13%.

[0049] Preparation Example 2

[0050] An end-capped polyurethane toughening agent is prepared by the following process:

[0051] 1) With minimal stirring, 74.38 g of the hydroxyl-terminated polyesterimine polyol from Preparation Example 1 was dehydrated at 100 °C under vacuum (0.1 MPa) for 1 hour.

[0052] 2) After cooling to 40 °C, add 16.77 g of IPDI and 0.015 g of catalyst, and react at 70 °C with stirring for 2 hours under a nitrogen atmosphere to obtain isocyanate-terminated polymer.

[0053] 3) When the NCO content in the polymer is 3.47%, 1.36 g of chain extender is added to the isocyanate-terminated polymer obtained in 2) under a nitrogen atmosphere, and the reaction is carried out at 70 °C with moderate stirring for 1 hour.

[0054] 4) When the NCO content in the polymer is 2.05%, add 6.80 g of blocking agent and 0.015 g of catalyst, react at 90°C with vigorous stirring for 3 hours, add 0.66 g of blocking agent, and continue the reaction for 2 hours to obtain a blocked polymer. To complete the isocyanate blocking, place the polymer in a 70°C oven overnight. The NCO content of the final product is less than 0.1%.

[0055] The hydroxyl-terminated polyesterimine polyol in the above preparation steps was prepared by Preparation Example 1. The catalyst was DBTL, the chain extender was 1,4-butanediol, and the blocking agent was p-tert-butylphenol. The hydroxyl-terminated polyesterimine polyol, polyisocyanate, chain extender, blocking agent, and catalyst were fed in a ratio of 74.38:16.77:1.36:7.46:0.03.

[0056] Its infrared spectrum is as follows Figure 2 As shown in the figure, the characteristic absorption peak of the end-capped polyurethane toughening agent is found at 3334.15 cm⁻¹. -1 An absorption peak for the stretching vibration of amino groups appears nearby, at 1675.00 cm⁻¹. -1 and 1631.00 cm -1 The absorption peak at 1252.44 cm⁻¹ represents the stretching vibration of the carboxyl group in the newly formed carbamate (-NHCOO-). -1 The absorption peak represents the asymmetric stretching vibration of the newly formed aryl ether bond (COC). The appearance of the above characteristic absorption peak indicates the presence of urethane groups in the structure, confirming that the above process can synthesize end-capped polyurethane toughening agents.

[0057] Preparation Examples 3-6

[0058] An end-capped polyurethane toughening agent differs from Preparation Example 2 in that the feed ratios of the various materials are different, as shown in Table 2:

[0059] Table 2: Comparison of material feeding ratios in Preparation Examples 3-6

[0060]

[0061] Preparation Examples 7-11

[0062] An end-capped polyurethane toughening agent differs from Preparation Example 2 in that the specific selection of each material is different, as shown in Table 3:

[0063] Table 3: Comparison of Material Selection in Preparation Examples 7-11

[0064]

[0065] Analysis of Tables 2 and 3 shows that by adjusting the types of chain extenders, end-capping agents, and catalysts, end-capped polyurethane toughening agents with different structures and properties can be obtained. Those skilled in the art can select different chain extenders, end-capping agents, and catalysts according to different application scenarios.

[0066] Performance testing

[0067] The epoxy resin compositions prepared in each example and comparative example were used as test objects. The tensile strength, elongation at break, and impact toughness of the epoxy resin cured products before and after high-temperature treatment at 200°C were then tested. The specific test steps and conditions are as follows:

[0068] Tensile strength and elongation at break test methods: Samples are prepared according to the method described in GB / T 2567-2008, and tensile tests are conducted at room temperature of 23±2℃. The load applied to the sample and the elongation of the sample are measured respectively, and then the tensile strength and elongation at break of the sample are calculated.

[0069] Impact toughness test method: Samples were prepared according to the method described in GB / T 2567-2008. The impact test was conducted at room temperature (23±2℃) using a simply supported beam impact tester. The impact strength of the sample was measured to characterize the toughness and strength of the composition. Each test was performed in parallel for three groups, and the average value was taken as the final measured value.

[0070] Examples 1-5

[0071] A high-strength, high-temperature resistant toughened epoxy resin, the weight (g) of each component of which is shown in Table 4, is prepared by the following process:

[0072] S1. First, mix epoxy resin and end-capped polyurethane toughening agent and heat to 80°C. After cooling to 40°C, add curing agent, accelerator and functional additive in sequence. After mixing, treat with ultrasonic vibration and then vacuum degas to obtain prepolymer.

[0073] The epoxy resin is epoxy resin BE188EL, the end-capped polyurethane toughening agent is prepared by Preparation Example 2, the curing agent is ultrafine dicyandiamide curing agent 100S (Evonik, Germany), the accelerator is UR500 (CVC Corpation), and the functional additive is fumed silica.

[0074] S2. Cast the prepolymer obtained in S1 into a mold, raise the temperature to 120℃ and cure for 2 hours, then continue to raise the temperature to 150℃ and cure for 3 hours. After curing, cool to room temperature in the furnace and demold to obtain a high-strength, high-temperature toughened epoxy resin.

[0075] Table 4: Components and their weights (g) of the high-strength, high-temperature toughened epoxy resins in Examples 1-5

[0076]

[0077] Comparative Example 1

[0078] A toughened epoxy resin differs from Example 1 in that the components and dosages are shown in Table 5. Its end-capped polyurethane toughening agent is prepared by reacting polytetramethylene ether glycol as a flexible chain with isocyanate monomers and then end-capping with a blocking agent, which corresponds to the background art.

[0079] Table 5: Components and their weights (g) of the toughened epoxy resin in Comparative Example 1

[0080]

[0081] The epoxy resin compositions from Examples 1-5 and Comparative Example 1 were extracted and their tensile strength, elongation at break, and impact toughness were tested before and after high-temperature treatment at 200°C. Three parallel tests were conducted for each group, and the average value of the test results was recorded in Table 6.

[0082] Table 6: Performance Comparison Table of Examples 1-5 and Comparative Example 1

[0083]

[0084] As can be seen from Table 6, the epoxy resin compositions obtained in Examples 1-5 all possess excellent high-temperature toughness, which meets their application requirements in chip packaging. Their tensile strength before high-temperature aging is 80.0-85.6 MPa, elongation at break is 5.6%-12.3%, and impact toughness is 30.8-44.1 KJ / m. 2 ;

[0085] Its tensile strength after high-temperature aging is 64.8-77.0 MPa, which is only 9.51%-19.00% lower than before high-temperature aging; its elongation at break is 4.0%-8.9%, which is 12.74%-30.89% lower than before high-temperature aging; and its impact toughness is 21.7-33.3 KJ / m. 2 Compared to before high-temperature aging, it only decreased by 18.18%-31.29%;

[0086] Within a certain range, as the amount of end-capped polyurethane toughening agent increases, the tensile strength, elongation at break, toughness, and high-temperature resistance of high-strength, high-temperature toughened epoxy resin also improve. However, when the amount of end-capped polyurethane toughening agent exceeds 36%, the tensile strength, elongation at break, and toughness tend to decrease.

[0087] Therefore, the preferred weight proportions of each component in the high-strength, high-temperature resistant toughened epoxy resin are as follows: A product with stable and uniform performance can be obtained by using any of the above-mentioned end-type polyurethane toughening agents (5-60 parts), epoxy resin (50-100 parts), curing agent (5-20 parts), and accelerator (0.01-5.0 parts).

[0088] In contrast, the data from Comparative Example 1 and the blank group show that the tensile strength after high-temperature aging decreased by 32.82% and 20.86% respectively compared to before high-temperature aging; the elongation at break decreased by 55.92% and 33.33% respectively compared to before high-temperature aging; and the impact toughness decreased by 67.28% and 39.91% respectively compared to before high-temperature aging. It is evident that the epoxy resin compositions using only the end-capped polyurethane toughening agent described in this application exhibit significantly lower decreases in tensile strength, elongation at break, and impact toughness in Examples 1-5 compared to the blank group in Comparative Example 1. Based on the above data, the theoretical basis and reasons are as follows:

[0089] The epoxy resin system toughened by the end-capped polyurethane toughening agent in this application benefits from the structure-activity relationship and ratio of isocyanate groups and polyesterimine polyol, which significantly improves the chain length of the end-capped polyurethane. Therefore, when applied to the epoxy resin system, it can impart excellent high strength and high temperature toughness without damaging the modulus of the epoxy resin matrix, thereby meeting its application conditions.

[0090] Examples 6-9

[0091] A high-strength, high-temperature resistant toughened epoxy resin differs from Example 1 in the application of the end-capped polyurethane toughening agent, as detailed in Table 7 below:

[0092] Table 7: Comparison of the usage of end-capped polyurethane toughening agents in Examples 6-9

[0093]

[0094] The epoxy resin compositions in Examples 6-9 were extracted and their tensile strength, elongation at break, and impact toughness were tested before and after high-temperature treatment at 200°C. Three parallel tests were conducted for each group, and the average value of the test results was recorded in Table 8.

[0095] Table 8: Performance Comparison Table of Examples 6-9

[0096]

[0097] As can be seen from Table 8, the epoxy resin compositions obtained in Examples 6-9 all possess excellent high-temperature toughness, which meets their application requirements in chip packaging. Their tensile strength before high-temperature aging is 79.5-84.6 MPa, elongation at break is 8.0-10.6%, and impact toughness is 33.8-39.8 KJ / m. 2 ;

[0098] Its tensile strength after high-temperature aging is 66.8-74.4 MPa, which is only 9.16%-15.97% lower than before high-temperature aging; its elongation at break is 6.4%-8.0%, which is 19.78%-24.53% lower than before high-temperature aging; and its impact toughness is 25.2-29.7 KJ / m. 2 Compared to before high-temperature aging, it only decreased by 21.93%-26.57%;

[0099] As shown in Table 8 above, by adjusting the amounts of hydroxyl-terminated polyesterimide polyol, polyisocyanate, chain extender, and capping agent, capped polyurethane toughening agents with different molecular weights and distributions can be obtained. To obtain capped polyurethane toughening agents, the preferred proportions of hydroxyl-terminated polyesterimide polyol and polyisocyanate are such that the [NCO] groups are stoichiometrically in excess of [OH], i.e., the molar ratio of [NCO] to [OH] is greater than 1. The use of chain extenders can regulate the hard segment structure and microphase separation degree of polyurethane; in this invention, the proportion of chain extenders is in the range of 0–4%. The preferred proportion of capping agents is such that the active hydrogen groups [H] in the capping agent are in excess of the residual [NCO], i.e., the molar ratio of active hydrogen [H] to residual [NCO] is greater than 1; in this invention, the proportion of capping agents is in the range of 0–30.

[0100] It is evident that appropriately increasing the dosage of hydroxyl-terminated polyesterimide polyol, polyisocyanate, chain extender, and blocking agent can improve the tensile strength, elongation at break, toughness, and heat resistance of the toughened epoxy resin. However, excessive dosage is detrimental.

[0101] Examples 10-14

[0102] A high-strength, high-temperature resistant toughened epoxy resin differs from Example 1 in the application of the end-capped polyurethane toughening agent, as detailed in Table 9:

[0103] Table 9: Comparison of the usage of end-capped polyurethane toughening agents in Examples 10-14

[0104]

[0105] The epoxy resin compositions in Examples 10-14 above were extracted and their tensile strength, elongation at break and impact toughness were tested before and after high temperature treatment at 200℃. Three parallel tests were conducted for each group, and the average value of the test results was recorded in Table 10.

[0106] Table 10: Performance Comparison Table of Examples 10-14

[0107]

[0108] As can be seen from Table 10, the epoxy resin compositions obtained in Examples 10-14 all possess excellent high-temperature toughness, which meets their application requirements in chip packaging. Their tensile strength before high-temperature aging is 78.8-91.6 MPa, elongation at break is 6.6%-11.6%, and impact toughness is 30.1-44.7 KJ / m. 2 ;

[0109] Its tensile strength after high-temperature aging is 62.8-85.3 MPa, which is only 5.64%-20.30% lower than before high-temperature aging; its elongation at break is 5.0%-9.6%, which is 7.35%-26.72% lower than before high-temperature aging; and its impact toughness is 22.5-36.4 KJ / m. 2 Compared to before high-temperature aging, it only decreased by 9.00%-27.07%.

[0110] Therefore, it can be seen that chain extenders with longer molecular chains can improve the elongation at break and toughness of toughened epoxy resin compositions. Hydroquinone hydroxyethyl ether, a chain extender containing a benzene ring structure, can improve the tensile strength and heat resistance of toughened epoxy resin compositions. Different types of end-capping agents result in a smaller decrease in strength, elongation at break, and toughness of toughened epoxy compositions after high-temperature aging compared to Comparative Example 1. However, different types of end-capping agents and different unsealing temperatures have a significant impact on the strength, elongation, and toughness of the cured product. The catalyst used in the synthesis of end-capped polyurethane toughening agents also has a certain influence on the properties of toughened epoxy resin compositions. DBTL is more beneficial to tensile strength, while bismuth neodecanoate is more beneficial to elongation at break, toughness, and temperature resistance.

[0111] It should also be noted that the curing agent and curing accelerator in this application can be conventionally replaced by those skilled in the art according to actual needs. Considering that the effect of their addition can be expected by those skilled in the art under the premise that the reaction principle remains unchanged, this application has not conducted individual tests in order to better control a single variable, and this should not be regarded as a limitation on the scope of protection of this application.

[0112] This specific preparation example is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this preparation example without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An end-capped polyurethane toughening agent, characterized in that, It is prepared by reacting hydroxyl-terminated polyesterimine polyol, polyisocyanate, chain extender and blocking agent in a feed ratio of (66-83):(14-20):(0-2):(0.5-15); The structural formula of the hydroxyl-terminated polyesterimine polyol is as follows: Formula (I); The structural formula of R is: .

2. The end-capped polyurethane toughening agent according to claim 1, characterized in that, It is prepared by the following process: 1) While stirring minimally in the reactor, dehydrate the hydroxyl-terminated polyesterimine polyol by evacuating it to a negative pressure of 0.09-0.1 MPa at 95-110 ℃ for 1-2 hours; 2) After cooling to 25-50 ℃, add polyisocyanate and catalyst, and react at 50-80 ℃ with stirring for 2-4 hours under nitrogen atmosphere to obtain isocyanate-terminated polymer; 3) When the NCO content in the polymer is 1.20-6.00%, under a nitrogen atmosphere, add a chain extender to the isocyanate-terminated polymer obtained in 2), and react at 50-80 °C with stirring for 1-2 hours; 4) When the NCO content in the polymer is 1.20-4.50%, continue to add blocking agent and catalyst, react at 80-110 ℃ with vigorous stirring for 2-12 hours, add more blocking agent, and continue to react for 1-4 hours to obtain end-capped polyurethane toughening agent. In order to complete the isocyanate blocking, the final product is placed in a 70 ℃ oven overnight, and its NCO content is 0-0.10%.

3. The end-capped polyurethane toughening agent according to claim 2, characterized in that, The hydroxyl-terminated polyesterimine polyol has a hydroxyl value of 28-224 mg / KOH.

4. The end-capped polyurethane toughening agent according to claim 2, characterized in that, The chain extender is selected from 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, ethylene glycol, diethylene glycol, 1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol / neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 1,8-octanediol, 2,4-diethyl-1,3-octanediol, trimethyl- One or more of the following: 1,6-hexanediol, 1,7-heptanediol, 4-propyl-1,8-octanediol, 1,9-nonanediol, hydroquinone dihydroxyethyl ether, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,4-diethyl-1,5-pentanediol, polyoxypropylene polyols with a molecular weight of 200-1000, trimethylolpropane, and glycerol.

5. The end-capped polyurethane toughening agent according to claim 2, characterized in that, The sealing agent is selected from one or more of phenol, cresol, xylenol, p-tert-butylphenol, 3-pentadecenylphenol, pyridinephenol, 2-trifluoroethanol, triphenylthiol, hexamethylenetetramine, dodecylthiol, acetanilide, caprolactam, dibutyl ketone oxime, 2,2'-diallylbisphenol A, 4-vinylphenol, p-aminophenol, cashew phenol, p-acetaminophen, and p-acetylphenol.

6. The end-capped polyurethane toughening agent according to claim 2, characterized in that, The catalyst is selected from dibutyltin dilaurate-DBTL or bismuth neodecanoate-III.

7. An epoxy resin composition, characterized in that, Includes epoxy resin and end-capped polyurethane toughening agent according to any one of claims 1-6.

8. The epoxy resin composition according to claim 7, characterized in that, The components include the following parts by weight: 5-60 parts of any one of the end-capped polyurethane toughening agents according to claims 1-6; 50-100 parts epoxy resin; 5-20 parts of curing agent; Accelerator 0.01-5.0 parts.

9. The epoxy resin composition according to claim 8, characterized in that, It also includes 0-10 parts of functional additives, wherein the functional additives are one or more of fillers, stabilizers, diluents, defoamers, thixotropic agents, coupling agents, and dispersants.

10. A method for preparing the epoxy resin composition according to any one of claims 7-9, characterized in that, Includes the following steps: S1. First, mix epoxy resin and end-capped polyurethane toughening agent and heat to 60-80 ℃. After cooling to 30-40 ℃, add curing agent, accelerator and functional additive in sequence. After mixing, treat with ultrasonic vibration and then vacuum degas to obtain prepolymer. S2. Cast the prepolymer obtained in S1 into a mold, raise the temperature to 100-120 ℃ and cure for 1-4 hours, continue to raise the temperature to 130-150 ℃ and cure for 2-5 hours. After curing, cool to room temperature with the furnace and demold to obtain high-strength, high-temperature toughened epoxy resin.

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