Low-viscosity high-strength epoxy resin impregnating adhesive and preparation method thereof

Abstract

The invention belongs to the field of epoxy resin impregnating adhesives, and discloses a low-viscosity high-strength epoxy resin impregnating adhesive and a preparation method thereof. The epoxy resin impregnating adhesive is prepared from a component A and a component B in a mass ratio of 100: (10-30), wherein the component A is prepared from the following components in percentage by weight: 50 to 70 percent of epoxy resin, 30 to 50 percent of polyfunctional group epoxy diluent and 0.05 to 1 percent of defoaming agent; the component B is prepared from the following components in percentage by weight: 50 to 70 percent of amine curing agent, 10 to 30 percent of polyether amine curing agent, 0.05 to 1 percent of accelerant and 1 to 2 percent of coupling agent; the polyfunctional group epoxy dilution is as follows: oil triglycidyl ether and diisocyanate are subjected to a reaction, and a polyfunctional group diluent Flex-E modified by urethane bond chain extension is obtained. The Flex-E obtained through modification has a polyurethane structure, when the Flex-E is used for diluting epoxy resin, the polyurethane structure can be introduced into the epoxy resin, and the toughness of an epoxy resin curing product is improved.

Description

Technical Field

[0001] The invention relates to the field of epoxy resin impregnation adhesive, in particular to a low-viscosity and high-strength epoxy resin impregnation adhesive and a preparation method thereof. Background Art

[0002] Epoxy resin is a general term for epoxy rings consisting of two or more epoxy rings consisting of one oxygen atom and two carbon atoms. Epoxy resin has excellent process performance, stability, and high cost performance, and is widely used in construction, transportation, aerospace, etc. Epoxy resin is one of the most widely used and best-performing resin types in the industry. Its low shrinkage, excellent adhesion, excellent mechanical properties, and acid and alkali resistance make it irreplaceable in adhesives, coatings, composite substrates, or aerospace.

[0003] Although epoxy resin has been widely promoted in many fields, due to the high viscosity and low strength of ordinary epoxy resin, the viscosity and strength of epoxy resin are required in occasions with high requirements, such as resin transfer molding process (RTM) and vacuum bag resin infusion molding process, which are subject to certain restrictions. Therefore, it is necessary to synthesize an epoxy resin with both low viscosity and high strength, which has important application value.

[0004] In addition, patent CN104448699A discloses a carbon fiber reinforced epoxy resin and a preparation method thereof, wherein the resin and the diluent are stirred evenly at 40-60°C to obtain component A, and the amine curing agent, the accelerator and the coupling agent are stirred evenly at 40-60°C to obtain component B. The mixed viscosity of the adhesive is (25°C) 820mPa.s, and the tensile strength is 72MPa.

[0005] For example, patent CN113930201 A discloses a low-viscosity epoxy resin material and its preparation method and application. First, the resin, diluent, coupling agent and defoamer are stirred and dispersed under vacuum to obtain component A, and the curing agent and accelerator are stirred evenly under heating conditions to obtain component B. The mixed viscosity of the adhesive is (25°C) 4500-7200mPa.s, and the tensile strength is 70MPa.

[0006] However, as mentioned above, the epoxy resins currently prepared by the methods of CN104448699A and CN113930201 A all have the problems of high viscosity and low tensile strength, which cannot meet the occasions with high requirements for the viscosity and strength of the epoxy resin, and the performance of the products needs to be improved. Summary of the invention

[0007] The invention aims to solve the technical problems of high viscosity and low tensile strength of existing domestic epoxy resins, and provides a low-viscosity and high-strength epoxy resin impregnating glue and a preparation method thereof.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The first aspect of the present invention provides a low-viscosity and high-strength epoxy resin impregnating adhesive, which comprises component A and component B in a mass ratio of 100:10-30; wherein:

[0010] Component A: 50-70wt% epoxy resin, 30-50wt% multifunctional epoxy diluent, 0.05-1wt% defoamer;

[0011] Component B: 50-70wt% amine curing agent, 10-30wt% polyetheramine curing agent, 0.05-1wt% accelerator, 1-2wt% coupling agent;

[0012] The multifunctional epoxy diluent is a Flex-E multifunctional diluent modified by the reaction of oil triglycidyl ether and diisocyanate to obtain an urethane bond extension modified Flex-E.

[0013] Preferably, the epoxy resin is one or a combination of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, bis(7-oxabicyclo 3-heptylmethyl) adipate, 1,2-epoxy-4-vinylcyclohexane, and 3,4-epoxycyclohexanecarboxylic acid methyl ester.

[0014] Preferably, the synthesis route of the Flex-E multifunctional diluent is as follows: Figure 1 shown.

[0015] Preferably, the synthesis method of the Flex-E multifunctional diluent comprises the following steps:

[0016] (1) Add 200-300 g of glycerol triglycidyl ether into a three-necked flask, stir with a disperser, and control the temperature so that the material in the three-necked flask is heated to 90-100° C., evacuate, and introduce nitrogen bubbling for dehydration for 1-3 hours. After dehydration is completed, cool the material in the three-necked flask to below 80° C.;

[0017] (2) 120-160 g of diisocyanate is added to a reaction bottle, and 150-300 ppm of benzoyl chloride is added; the temperature is controlled to raise the temperature of the material in the three-necked flask to 100-110° C. and react for 24-48 hours; the NCO content is tested, NCO ≤ 0.2%, and the material in the three-necked flask is cooled to room temperature to obtain a Flex-E multifunctional diluent.

[0018] Preferably, the defoaming agent is one or a combination of polyether defoaming agents, higher alcohols, and silicone defoaming agents.

[0019] Preferably, the amine curing agent is One or more of alkyl diamine (MDA), N-aminoethylpiperazine (N-AEP), and isophorone diamine (IPD).

[0020] Preferably, the accelerator is one or a combination of triethanolamine, 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), dimethylbenzylamine, and N-diglycidylaniline.

[0021] Preferably, the coupling agent is one or a combination of γ-(2,3-propylene oxide)propyltrimethoxysilane, vinyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

[0022] Preferably, the diisocyanate is one or a combination of toluene diisocyanate (TDI), diphenylmethane-4,4'-diisocyanate (MDI), and hexamethylene diisocyanate (HDI).

[0023] The second aspect of the present invention is to provide a method for preparing the low-viscosity and high-strength epoxy resin impregnated adhesive, comprising the following steps:

[0024] (1) adding epoxy resin, multifunctional diluent and defoamer into a single-mouth bottle in sequence at room temperature and stirring with a stirrer for 0.5 h until the mixture is uniform and there is no obvious stratification, thereby preparing component A;

[0025] (2) adding an amine curing agent, a polyetheramine curing agent, an accelerator and a coupling agent into a 500 ml single-mouth bottle in sequence at room temperature and stirring for 0.5 h using a stirrer until the mixture is uniform and there is no obvious stratification, thereby preparing component B;

[0026] (3) Components A and B are mixed and stirred evenly in a mass ratio of 100:10-30, and vacuum-degassing is performed at room temperature for 10-15 minutes to obtain a resin mixture.

[0027] The synthesis principle of Flex-E multifunctional diluent is as follows: the epoxy value of glycerol triglycidyl ether on the market is 0.58-0.71. If its epoxy value is calculated according to the structure of glycerol triglycidyl ether, the epoxy value should be 1.15. The difference between the two is large. The reason may be that in the production process of glycerol triglycidyl ether, the continuous addition side reaction in the first step reaction is difficult to control, resulting in a large number of other terminal epoxy products containing polyhydroxyl groups on the main chain in addition to the generated glycerol triglycidyl ether during the second step of hydrolysis, making the epoxy value of the product lower than the theoretical value. The hydroxyl groups in glycerol triglycidyl ether react with diisocyanate to generate carbamate. Through this reaction, the terminal epoxy products with hydroxyl groups in glycerol triglycidyl ether are coupled to obtain the urethane bond chain extension modified Flex-E multifunctional diluent. The modified Flex-E has a polyurethane structure. When Flex-E is used to dilute epoxy resin, the polyurethane structure will be introduced into the epoxy resin, which improves the toughness of the epoxy resin cured product.

[0028] The present invention adopts the above technical solution, which has the following technical effects compared with the prior art:

[0029] The present invention first synthesizes a new epoxy diluent, and then mixes it with a resin to obtain a low-viscosity and high-strength epoxy resin impregnated adhesive; the modified Flex-E has a polyurethane structure, and when the epoxy resin is diluted with Flex-E, the polyurethane structure will be introduced into the epoxy resin, thereby improving the toughness of the epoxy resin cured product, and can effectively solve the problems of high viscosity and low tensile strength of the existing epoxy resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The synthetic process route of the Flex-E multifunctional diluent of the present invention;

[0031] Figure 2 It is the infrared spectrum of triglycidyl ether and Flex-E multifunctional diluent of the present invention. DETAILED DESCRIPTION

[0032] The present invention is described in detail and specifically by specific examples below to provide a better understanding of the present invention, but the following examples do not limit the scope of the present invention.

[0033] Example 1 Press Figure 1 The process shown is used to synthesize Flex-E multifunctional diluent

[0034] (1) Add 210 g of glycerol triglycidyl ether into a three-necked flask, stir with a disperser, and control the temperature so that the material in the three-necked flask is heated to 90-100° C., evacuate, and introduce nitrogen bubbling for dehydration for 1-3 hours. After dehydration is completed, cool the material in the three-necked flask to below 80° C.;

[0035] (2) 90 g of diisocyanate was added to a reaction bottle, and 200 ppm of benzoyl chloride was added; the temperature was controlled to raise the temperature of the material in the three-necked flask to 105° C. and reacted for 48 hours; the NCO content was tested, NCO ≤ 0.2%, and the material in the three-necked flask was cooled to room temperature to obtain Flex-E multifunctional diluent.

[0036] Figure 2 The black line in the lower middle is the infrared spectrum of triglycidyl ether, 3500cm -1 is the absorption peak of -OH in the system; 1100cm -1 The broad and strong absorption peak at 910cm is the infrared absorption peak of the antisymmetric stretching vibration of triglycidyl ether with COC ether structure; -1 The absorption peak at corresponds to the characteristic absorption peak of the epoxy group.

[0037] and Figure 2 The red line in the upper middle is the infrared spectrum of Flex-E. By comparing it with the black line below, it can be found that the infrared spectrum of Flex-E is 2270cm -1 There is no -NCO characteristic peak, and 3300cm -1 and 1730cm -1 An absorption peak appears at , indicating that the diisocyanate added to triglycidyl ether has fully reacted with the -OH in triglycidyl ether to generate Flex-E with the characteristic structure of carbamate.

[0038] also, Figure 2 The red line shown in the upper middle is Figure 2 Compared to the black line shown in the lower middle section, at 3500cm -1 The -OH absorption peak intensity at the position dropped significantly, verifying that the -OH in triglycidyl ether reacted with diisocyanate, resulting in a reduction of -OH in the system.

[0039] Example 2 Preparation of a low-viscosity, high-strength epoxy resin impregnated adhesive

[0040] Step 1: Add (80 g) 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexyl carboxylate, (20 g) Flex-E multifunctional diluent, and (1 g) BYK-A530 defoamer into a 500 ml single-necked bottle at room temperature and stir with a stirrer for 0.5 h until the mixture is evenly mixed without obvious stratification.

[0041] Step 2: Add (70 g) isophorone diamine, (30 g) polyetheramine D230, (5 g) 2,4,6-tris(dimethylaminomethyl)phenol, and (1 g) γ-(2,3-propylene oxide)propyltrimethoxysilane into a 500 ml single-necked bottle in sequence at room temperature and stir with a stirrer for 0.5 h until the mixture is uniformly mixed without obvious stratification.

[0042] Step 3: Mix components A and B at a ratio of 100:30 to obtain epoxy resin cured product, and vacuum degas the product for 15 minutes to obtain low-viscosity and high-strength epoxy resin impregnation adhesive.

[0043] Example 3 Preparation of a low-viscosity, high-strength epoxy resin impregnated adhesive

[0044] Step 1: Add (70 g) 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexyl carboxylate, (30 g) Flex-E multifunctional diluent, and (1 g) BYK-A530 defoamer into a 500 ml single-necked bottle at room temperature and stir with a stirrer for 0.5 h until the mixture is evenly mixed without obvious stratification.

[0045] Step 2: Add (70 g) isophorone diamine, (30 g) polyetheramine D230, (5 g) 2,4,6-tris(dimethylaminomethyl)phenol, and (1 g) γ-(2,3-propylene oxide)propyltrimethoxysilane into a 500 ml single-necked bottle in sequence at room temperature and stir with a stirrer for 0.5 h until the mixture is uniformly mixed without obvious stratification.

[0046] Step 3: Components A and B are mixed at a ratio of 100:30 to obtain epoxy resin cured product, and vacuum degassing is performed for 15 minutes to obtain low-viscosity and high-strength epoxy resin impregnating glue.

[0047] Example 4 Preparation of a low-viscosity, high-strength epoxy resin impregnated adhesive

[0048] Step 1: Add (60 g) 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexyl carboxylate, (40 g) Flex-E multifunctional diluent, and (1 g) BYK-A530 defoamer into a 500 ml single-necked bottle at room temperature and stir with a stirrer for 0.5 h until the mixture is evenly mixed without obvious stratification.

[0049] Step 2: Add (70 g) isophorone diamine, (30 g) polyetheramine D230, (5 g) 2,4,6-tris(dimethylaminomethyl)phenol, and (1 g) γ-(2,3-propylene oxide)propyltrimethoxysilane into a 500 ml single-necked bottle in sequence at room temperature and stir with a stirrer for 0.5 h until the mixture is uniformly mixed without obvious stratification.

[0050] Step 3: Components A and B are mixed at a ratio of 100:30 to obtain epoxy resin cured product, and vacuum degassing is performed for 15 minutes to obtain low-viscosity and high-strength epoxy resin impregnating glue.

[0051] Comparative Example 1 Preparation of a low-viscosity and high-strength epoxy resin impregnated adhesive

[0052] Step 1: Add (70 g) 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, (30 g) C12-C14 glycidyl ether, and (1 g) BYK-A530 defoamer into a 500 ml single-necked bottle at room temperature and stir with a stirrer for 0.5 h until the mixture is uniformly mixed without obvious stratification.

[0053] Step 2: Add (70 g) isophorone diamine, (30 g) polyetheramine D230, (5 g) 2,4,6-tris(dimethylaminomethyl)phenol, and (1 g) γ-(2,3-propylene oxide)propyltrimethoxysilane into a 500 ml single-necked bottle in sequence at room temperature and stir with a stirrer for 0.5 h until the mixture is uniformly mixed without obvious stratification.

[0054] Step 3: Mix components A and B at a ratio of 100:30 to obtain epoxy resin cured product, and vacuum degas the product for 15 minutes to obtain low-viscosity and high-strength epoxy resin impregnation adhesive.

[0055] Comparative Example 2 Preparation of a low-viscosity and high-strength epoxy resin impregnated adhesive

[0056] Step 1: Add (70 g) 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, (30 g) 1,4-butanediol glycidyl ether, and (1 g) BYK-A530 defoamer into a 500 ml single-necked bottle at room temperature and stir with a stirrer for 0.5 h until the mixture is uniformly mixed without obvious stratification.

[0057] Step 2: Add (70 g) isophorone diamine, (30 g) polyetheramine D230, (5 g) 2,4,6-tris(dimethylaminomethyl)phenol, and (1 g) γ-(2,3-propylene oxide)propyltrimethoxysilane into a 500 ml single-necked bottle in sequence at room temperature and stir with a stirrer for 0.5 h until the mixture is uniformly mixed without obvious stratification.

[0058] Step 3: Mix components A and B at a ratio of 100:30 to obtain epoxy resin cured product, and vacuum degas the product for 15 minutes to obtain low-viscosity and high-strength epoxy resin impregnation adhesive.

[0059] Comparative Example 3 Preparation of a low-viscosity and high-strength epoxy resin impregnated adhesive

[0060] Step 1: Add (70 g) 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, (30 g) propylene glycol triglycidyl ether, and (1 g) BYK-A530 defoamer into a 500 ml single-necked bottle at room temperature and stir with a stirrer for 0.5 h until the mixture is uniformly mixed without obvious stratification.

[0061] Step 2: Add (70 g) isophorone diamine, (30 g) polyetheramine D230, (5 g) 2,4,6-tris(dimethylaminomethyl)phenol, and (1 g) γ-(2,3-propylene oxide)propyltrimethoxysilane into a 500 ml single-necked bottle in sequence at room temperature and stir with a stirrer for 0.5 h until the mixture is uniformly mixed without obvious stratification.

[0062] Step 3: Mix components A and B at a ratio of 100:30 to obtain epoxy resin cured product, and vacuum degas the product for 15 minutes to obtain low-viscosity and high-strength epoxy resin impregnation adhesive.

[0063] Performance Test:

[0064] The epoxy resin impregnated adhesives prepared in Example 2, Example 3 and Example 4 were used as the experimental group, and the epoxy resin impregnated adhesives prepared in Comparative Example 1, Comparative Example 2 and Comparative Example 3 were used as the control group. Performance tests were performed respectively, and the test results are shown in Table 1 below.

[0065] Table 1 Performance test results of Examples 2 to 4 and Comparative Examples 1 to 3

[0066]

[0067] The Flex-E multifunctional diluent used in the present invention is modified from a multifunctional glycidyl ether, which contains multiple hydroxyl groups, epoxy groups and ether bonds. The polyurethane structure is introduced through the modification, and its multiple functional groups are cross-linked with the resin to form a larger network cross-linked state, thereby improving the performance of the resin cured product.

[0068] It can be seen from Table 1 that compared with Comparative Example 1, Comparative Example 2, Comparative Example 2, and Comparative Example 3, Example 2, Example 3, and Example 4 not only have low viscosity, but also have strong properties such as tensile strength and flexural strength. This shows that the addition of Flex-E multifunctional diluent improves performance better than ordinary diluents and has lower viscosity.

[0069] Among the three embodiments, the viscosity of the glue of embodiment 3 is lower than that of embodiment 2, and the flow and filling speed is faster. The viscosity of the glue of embodiment 4 is slightly higher, but the tensile strength, bending strength and other properties of embodiment 3 are higher than those of embodiment 2 and embodiment 4. The performance of embodiment 3 is the best among several formulas.

[0070] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A low-viscosity, high-strength epoxy resin impregnating adhesive, characterized in that: It is composed of component A and component B in a mass ratio of 100:10-30; wherein: Component A: 50-70wt% epoxy resin, 30-50wt% multifunctional epoxy diluent, 0.05-1wt% defoamer; Component B: 50-70wt% amine curing agent, 10-30wt% polyetheramine curing agent, 0.05-1wt% accelerator, 1-2wt% coupling agent; Among them, the multifunctional epoxy diluent is a triglycidyl ether with an epoxy value of 0.58-0.71 that reacts with diisocyanate, wherein the diisocyanate reacts with the hydroxyl group in the triglycidyl ether to reduce the hydroxyl group in the system and generate a characteristic structure with carbamate, thereby obtaining a Flex-E multifunctional diluent modified by urethane bond chain extension.

2. The low-viscosity and high-strength epoxy resin impregnating adhesive according to claim 1, characterized in that: The epoxy resin is one or a combination of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, bis(7-oxabicyclo 3-heptylmethyl) adipate, 1,2-epoxy-4-vinylcyclohexane, and 3,4-epoxycyclohexanecarboxylic acid methyl ester.

3. The low-viscosity and high-strength epoxy resin impregnating adhesive according to claim 1, characterized in that: The synthesis route of the Flex-E multifunctional diluent is shown in FIG1 .

4. The low-viscosity and high-strength epoxy resin impregnating adhesive according to claim 3, characterized in that: The synthesis method of the Flex-E multifunctional diluent comprises the following steps: (1) Add 200-300 g of glycerol triglycidyl ether into a three-necked flask, stir with a disperser, and control the temperature so that the material in the three-necked flask is heated to 90-100° C., evacuate, and introduce nitrogen bubbling for dehydration for 1-3 hours. After dehydration is completed, cool the material in the three-necked flask to below 80° C.; (2) 120-160 g of diisocyanate is added to a reaction bottle, and 150-300 ppm of benzoyl chloride is added; the temperature is controlled to raise the temperature of the material in the three-necked flask to 100-110° C. and react for 24-48 hours; the NCO content is tested, NCO ≤ 0.2%, and the material in the three-necked flask is cooled to room temperature to obtain a Flex-E multifunctional diluent.

5. The low-viscosity and high-strength epoxy resin impregnating adhesive according to claim 1, characterized in that: The defoaming agent is one or a combination of polyether defoaming agents, higher alcohols, and silicone defoaming agents.

6. The low-viscosity and high-strength epoxy resin impregnating adhesive according to claim 1, characterized in that: The amine curing agent is one or a combination of 4-amino-α, α-4-trimethyl-cyclohexanemethylamine, N-aminoethylpiperazine (N-AEP), and isophoronediamine (IPD).

7. The low-viscosity and high-strength epoxy resin impregnating adhesive according to claim 1, characterized in that: The accelerator is one or a combination of triethanolamine, 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), dimethylbenzylamine, and N-diglycidylaniline.

8. The low-viscosity and high-strength epoxy resin impregnating adhesive according to claim 1, characterized in that: The coupling agent is one or a combination of γ-(2,3-propylene oxide)propyltrimethoxysilane, vinyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

9. The low-viscosity and high-strength epoxy resin impregnating adhesive according to claim 1, characterized in that: The diisocyanate is one or a combination of toluene diisocyanate (TDI), diphenylmethane-4,4'-diisocyanate (MDI), and hexamethylene diisocyanate (HDI).

10. A method for preparing the low-viscosity and high-strength epoxy resin impregnating adhesive as claimed in any one of claims 1 to 9, characterized in that: The steps include: (1) adding epoxy resin, multifunctional diluent and defoamer into a single-mouth bottle in sequence at room temperature and stirring with a stirrer for 0.5 h until the mixture is uniform and there is no obvious stratification, thereby preparing component A; (2) adding an amine curing agent, a polyetheramine curing agent, an accelerator and a coupling agent into a 500 ml single-mouth bottle in sequence at room temperature and stirring for 0.5 h using a stirrer until the mixture is uniform and there is no obvious stratification, thereby preparing component B; (3) Components A and B are mixed and stirred evenly in a mass ratio of 100:10-30, and vacuum-degassing is performed at room temperature for 10-15 minutes to obtain a resin mixture.

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