Epoxy resin composition for single-component liquid molding and preparation method therefor

Abstract

Provided in the present invention are an epoxy resin composition for single-component liquid molding and a preparation method therefor. Said resin composition comprises the following components in percentage by weight: 7-35% of a tetrafunctional epoxy resin, 16-40% of a trifunctional epoxy resin, 7-21% of a bifunctional epoxy resin, 1-6% of a toughening agent and 34-40% of a low-activity curing agent, the toughening agent being a thermoplastic resin, the low-activity curing agent being an aromatic amine curing agent into which a chlorine electron-withdrawing group is introduced to the ortho-position or para-position of an amino group, and the ratio of the mole number of the low-activity curing agent to the total mole number of all the epoxy resins being (88-110):100. The present invention uses the aromatic amine curing agent containing a chlorine electron-withdrawing group for lowering the curing reaction activity of the epoxy resin composition, thereby prolonging the operable time of the single-component liquid molding resin system and achieving a relatively wide process operation window. Said epoxy resin composition is suitable for manufacturing composite material primary load-bearing structures in civil aviation by means of automated dry fiber placement-liquid molding technology.

Description

One-component liquid molding epoxy resin composition and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a single-component liquid molding resin composition. Background Art

[0002] Composite materials offer advantages such as lightweight, high strength, integrated structure and function, and integrated design and manufacturing. The use of carbon fiber reinforced composites, in particular, can effectively reduce aircraft structural weight, improve fuel efficiency, and enhance aircraft reliability. Currently, the primary method for producing advanced resin-based carbon fiber composite structural components for aerospace applications is prepreg autoclave forming. Manufacturing costs account for 60-70% of the composite material's cost. The high cost of traditional autoclave processes significantly limits the application of advanced resin-based composite materials in aviation.

[0003] Liquid composite molding (LCM) is a low-cost composite molding technology that involves injecting liquid resin into a closed mold cavity containing a fiber-reinforced material preform. The liquid resin flows and infiltrates the fiber preform in the mold cavity, expelling the gas in the mold cavity, and completing the molding of the composite product under a preset temperature program. In recent years, low-cost liquid molding technology has become a focus of research and development in the field of aviation composite material manufacturing. It has the advantages of low design and manufacturing costs, precise control of part dimensions, high operational freedom, and suitability for integrated manufacturing of complex structures. Automatic fiber placement to prepare dry fiber preforms can achieve the molding of preforms with high fiber volume content, significantly improving quality stability and precision. It is expected that liquid molding technology will replace prepreg / autoclave technology in the main load-bearing structures of civil aviation.

[0004] The composite materials used in the main load-bearing structures of civil aviation are large in size, and their manufacture using liquid molding requires a long operating process window (window period). The viscosity must not exceed 300 mPa·s at the general injection temperature (usually below 100°C) and must be maintained for more than 5 hours. They must also possess characteristics such as high temperature resistance, high toughness, low viscosity, low volatility, and few bubbles. However, the matrix resins used in existing liquid molding technologies cannot simultaneously meet the above requirements. For example, Chinese invention patent CN 115124816 B invented an RTM epoxy resin composition. The RTM operating process window of this resin at 80°C is only 200 minutes (viscosity <0.5 Pa·s), which cannot meet the operating process window requirements for preparing large composite materials using dry fiber automated placement liquid molding technology. Chinese invention patent CN1111186C discloses a one-component, low-viscosity, long-term storage thermosetting epoxy resin system. By adding an onium salt as a primary catalyst and a co-catalyst as an active hydrogen donor to the epoxy resin, the resin can be stored for over a year at room temperature. However, the resin suffers from low heat resistance and poor toughness, failing to meet the high heat resistance and toughness requirements of the aviation industry. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a single-component liquid molding resin composition with low viscosity, high toughness, wide window, and high heat resistance, which is suitable for dry fiber automatic placement liquid molding technology, especially suitable for dry fiber automatic placement liquid molding technology to manufacture civil aviation composite main load-bearing structural parts.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides a one-component liquid molding resin composition, comprising the following components in percentage by weight:

[0007]

[0008] The toughening agent is a thermoplastic resin; the low-activity curing agent is an aromatic amine curing agent with a chlorine-containing electron-withdrawing group introduced at the ortho or para position of the amino group; the ratio of the molar number of the low-activity curing agent to the total molar number of all epoxy resins in the tetrafunctional epoxy resin, the trifunctional epoxy resin, and the bifunctional epoxy resin is (88-110):100.

[0009] The one-component liquid molding epoxy resin composition of the present invention selects a variety of epoxy resins with different functionalities as the main resin, selects an aromatic amine curing agent with a chlorine-containing electron-withdrawing group, reduces the curing reaction activity of the epoxy resin system, prolongs the operable time of the one-component liquid molding resin system, and has a wider operating window. At the same time, the one-component liquid molding epoxy resin composition of the present invention adds a thermoplastic resin for toughening, and produces synergistic toughening and interlayer toughening with dry fibers with thermoplastic resin toughening agents added to the surface. The obtained carbon fiber composite material has a post-impact compressive strength of more than 280MPa. By adjusting the component structure and proportion of the main resin, low-activity curing agent, thermoplastic toughening agent, etc., a one-component liquid molding resin composition with low viscosity, long window period, high toughness, and high temperature resistance is developed.

[0010] Preferably, the tetrafunctional epoxy resin is selected from one or both of 4,4'-diaminodiphenylmethane tetraglycidylamine epoxy resin (AG-80 epoxy resin) and 3,3'-diethyl-4,4'-diaminodiphenylmethane tetraglycidylamine (Tetraglycidyl-3,3'-diethyl-4,4'-diaminodiphenyl methane, AG-70 epoxy resin); the epoxy equivalent of the tetrafunctional epoxy resin is 118-130 g / mol.

[0011]

[0012] Preferably, the trifunctional epoxy resin is selected from one or more of p-aminophenol triglycidyl epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester; the epoxy equivalent weight of the trifunctional epoxy resin is 96-118 g / mol. Further preferably, the p-aminophenol triglycidyl epoxy resin is selected from one or more of AFG-90 epoxy resin, AFG-90H epoxy resin, and AFG-90HM epoxy resin.

[0013] Preferably, the difunctional epoxy resin is selected from bisphenol F epoxy resin; the epoxy equivalent weight of the difunctional epoxy resin is 160-190 g / mol.

[0014] Preferably, the bisphenol F epoxy resin is selected from one or more of NPEF-170 epoxy resin, NPEF-175 epoxy resin and NPEF-180 epoxy resin.

[0015] Preferably, the thermoplastic resin is selected from one or more of polyethersulfone, nylon, polyetheretherketone and polyaryletherketone.

[0016] Preferably, the low-activity curing agent is selected from one or more of 1,8-dichloro-naphthalene-2,7-diyldiamine, 4,4'-methylene-bis-(3-chloro-2,6-diethyl)aniline (MCDEA) and 3,3'-dichloro-4,4'-methylenediaminodiphenylmethane (MOCA).

[0017]

[0018] 3,3'-Dichloro-4,4'-diaminodiphenylmethane (MOCA)

[0019]

[0020] 4,4-Methylenebis(3-chloro-2,6-diethyl)aniline (MCDEA)

[0021] The present invention also provides a method for preparing the one-component liquid molding resin composition described in the above technical solution, comprising the following steps:

[0022] S1, taking a trifunctional epoxy resin with a mass of 1-1.8 times that of a low-activity curing agent, stirring and heating to 80°C, then adding the low-activity curing agent, mixing at 80°C, vacuum degassing until transparent, and cooling to obtain component A;

[0023] S2, mixing all the tetrafunctional epoxy resin, the difunctional epoxy resin and the remaining trifunctional epoxy resin at 75-85° C., adding a toughening agent, mixing at 120° C., vacuum degassing until transparent, and then cooling to obtain component B;

[0024] S3, mixing component A and component B at 80-90° C., and vacuuming for 30-60 minutes to remove air to obtain a one-component liquid molding resin composition;

[0025] There is no order for steps S1 and S2.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1) The present invention utilizes a low-reactivity aromatic amine curing agent with a chlorine-containing electron-withdrawing group, resulting in a one-component liquid molding resin composition with low reactivity under injection process conditions. This extends the resin's window of operation at injection temperature, making it suitable for the production of large composite components for civil aviation using a dry fiber automated placement liquid molding process. The matrix resin produced from this one-component liquid molding resin composition exhibits a process operating window (resin viscosity ≤ 300 mPa·s at an injection temperature of 100°C) exceeding 6 hours.

[0028] 2) The present invention uses a variety of epoxy resins with different numbers of functional groups and selects a synergistic ratio as the main resin, and uses a multifunctional aromatic amine as a curing agent, so that the single-component liquid molding resin composition has high heat resistance.

[0029] 3) The present invention adds a thermoplastic resin as a toughening agent to the one-component liquid molding resin composition, which produces synergistic toughening and interlayer toughening with the dry fiber with the thermoplastic resin toughening agent added to the surface. The resulting carbon fiber composite material has a post-impact compressive strength higher than 280 MPa. The matrix resin made from the one-component liquid molding resin composition of the present invention has high toughness and impact strength.

[0030] 4) When preparing a one-component liquid molding matrix resin, the present invention disperses the toughening agent and the curing agent separately and dissolves them in different epoxy resins, and vacuum degasses them separately. This can accelerate the dissolution rate of the curing agent in the epoxy resin and improve the vacuum degassing efficiency. Compared with mixing all the raw materials together and then performing vacuum degassing, the vacuum degassing time can be reduced by more than 30 minutes, minimizing the problem of shortening the matrix resin window period due to vacuum degassing. The preparation method of the one-component liquid molding matrix resin provided by the present invention improves the bending strength of the resin casting by 5-10% compared with the method of vacuum degassing after mixing together.

[0031] In summary, the one-component liquid molding resin composition provided by the present invention and the one-component liquid molding matrix resin made from the same have the characteristics of a wide window period, high heat resistance, and high toughness, and are suitable for manufacturing civil aviation composite main load-bearing structures, such as wings and reinforced wall panels, using dry fiber automatic placement liquid molding technology. DETAILED DESCRIPTION

[0032] The technical solutions of the present invention will be described below in conjunction with embodiments. Obviously, the embodiments described are only a portion of the embodiments of the present invention, rather than all of the embodiments. It should be noted that all other embodiments obtained by those of ordinary skill in the art based on these embodiments of the present invention are within the scope of protection of the present invention.

[0033] The present invention provides a one-component liquid molding resin composition, comprising the following components in percentage by weight:

[0034]

[0035] The present invention selects a tetrafunctional epoxy resin, a trifunctional epoxy resin, and a bifunctional epoxy resin as the main resins, and when the three are compounded in a mass ratio of (7-35):(16-40):(7-21), they have a synergistic effect and can further improve the heat resistance of the base resin. Preferably, the mass ratio of the tetrafunctional epoxy resin, the trifunctional epoxy resin, and the bifunctional epoxy resin is (20-32):(17-25):(10-16).

[0036] In the present invention, tetrafunctional epoxy resins include, but are not limited to, one or more of 4,4'-diaminodiphenylmethane tetraglycidylamine epoxy resin (AG-80 epoxy resin) and 3,3'-diethyl-4,4'-diaminodiphenylmethane tetraglycidylamine (AG-70 epoxy resin). Preferably, the tetrafunctional epoxy resin is AG-80 epoxy resin, or a combination of AG-70 epoxy resin and AG-80 epoxy resin. In the present invention, the tetrafunctional epoxy resin preferably has an epoxy equivalent weight of 118-130 g / mol.

[0037] In the present invention, trifunctional epoxy resins include, but are not limited to, one or more of p-aminophenol triglycidyl epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester. Preferably, p-aminophenol triglycidyl epoxy resin is selected from one or more of AFG-90 epoxy resin, AFG-90H epoxy resin, and AFG-90HM epoxy resin. AFG-90H epoxy resin is a purified product of AFH-90 resin by molecular distillation, and AFG-90MH epoxy resin is a purified product of AFH-90M resin by molecular distillation using a thin film evaporation device. Further preferably, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester is selected from one or more of TDE-85 epoxy resin and TDE-85H epoxy resin. TDE-85H epoxy resin is a purified product of TDE-85 epoxy resin by molecular distillation using a thin film evaporation device. In the present invention, the trifunctional epoxy resin is preferably a combination of AFG-90HM epoxy resin and AFG-90H epoxy resin. In the present invention, the epoxy equivalent weight of the trifunctional epoxy resin is preferably 96-118 g / mol.

[0038] In the present invention, the difunctional epoxy resin includes a bisphenol F epoxy resin; preferably, the bisphenol F epoxy resin is one or more of NPEF-170 epoxy resin, NPEF-175 epoxy resin, and NPEF-180 epoxy resin. Preferably, the difunctional epoxy resin is NPEF-170 epoxy resin. In the present invention, the epoxy equivalent weight of the difunctional epoxy resin is preferably 160-190 g / mol.

[0039] In the present invention, the toughening agent is a thermoplastic resin; the thermoplastic resin is preferably selected from one or more of polyethersulfone (PES), nylon, polyetheretherketone (PEEK), and polyaryletherketone (PAEK). Preferably, the toughening agent is polyethersulfone (PES). In the present invention, the toughening agent accounts for 1-6% of the mass of the single-component liquid molding resin composition, and within this range, the toughness of the resin can be significantly improved. In some specific embodiments of the present invention, the toughening agent can account for 2%, 3%, 5%, 7%, 9%, 10%, etc., of the total mass of the epoxy resin.

[0040] In the present invention, the low-activity curing agent is an aromatic amine curing agent that introduces a chlorine-containing electron-withdrawing group at the ortho or para position of the amino group. Introducing an electron-withdrawing group such as chlorine at the ortho or para position of the aromatic amine curing agent and adding it to the main resin of the present invention can reduce the curing reaction activity of the entire one-component liquid molding resin composition, reduce the curing reaction during the production, storage, transportation, and use of the one-component liquid molding resin composition, and extend the operating window and storage period of the one-component liquid molding resin composition. In the present invention, one or more of 4,4'-methylene-bis-(3-chloro-2,6-diethylaniline) and 3,3'-dichloro-4,4'-diaminodiphenylmethane is selected. The low-activity curing agent of the present invention can be purchased commercially. In the present invention, the ratio of the molar number of the low-activity curing agent to the total molar number of all epoxy resins in the tetrafunctional epoxy resin, trifunctional epoxy resin, and bifunctional epoxy resin is (88-110):100; more preferably (95-100):100.

[0041] The present invention also provides a method for preparing the one-component liquid molding resin composition described in the above technical solution, the preparation method comprising the following steps:

[0042] S1, taking a trifunctional epoxy resin with a mass of 1-1.8 times that of a low-activity curing agent, stirring and heating to 80°C, then adding the low-activity curing agent, mixing at 80°C, vacuum degassing until transparent, and cooling to obtain component A;

[0043] S2, mixing all the tetrafunctional epoxy resin, the difunctional epoxy resin and the remaining trifunctional epoxy resin at 75-85° C., adding a toughening agent, mixing at 120° C., vacuum degassing until transparent, and then cooling to obtain component B;

[0044] S3, mixing component A and component B at 80-90°C, and vacuuming for 30-60 minutes to remove air to obtain a single-component liquid molding matrix resin with a wide window period;

[0045] There is no order for steps S1 and S2.

[0046] The general order of ingredients for one-component liquid molding epoxy resin system is to add toughening agent after heating various epoxy resins to make them transparent, stir evenly until they are dissolved and transparent, add curing agent and stir until the resin system is transparent after cooling, and in order to eliminate the bubbles in the resin system, the whole process needs to be vacuumed to remove the bubbles. Because after adding toughening agent in epoxy resin, the viscosity of resin increases significantly, the deaeration time of resin system will be significantly extended, the contact time of resin and curing agent is increased, resulting in the reaction of resin and curing agent, and the operational window period is shortened. The preparation method of one-component liquid molding matrix resin of the present invention is to dissolve curing agent and toughening agent separately in different epoxy resins, and vacuum deaeration can accelerate curing agent dissolution speed, improve vacuuming efficiency, and minimize the problem of resin operational window period decline caused by vacuuming, and the obtained one-component liquid molding matrix resin does not need vacuum deaeration before use, which is convenient for subsequent composite material molding process.

[0047] The technical solutions provided by the present invention are described in detail below with reference to the examples, but they should not be construed as limiting the scope of protection of the present invention. Experimental methods in the following examples where specific conditions are not specified are generally performed under conventional conditions or conditions recommended by the manufacturer.

[0048] Example 1

[0049] Add 98g AFG-90MH epoxy resin, 59g AG-80 epoxy resin, and 85g NPEF-170 epoxy resin into a double planetary mixer, stir and gradually heat to about 80°C, add 45g nylon in batches, gradually heat to 120°C, remove bubbles in vacuum, and cool until transparent. Set aside, record as component B;

[0050] Add 192 g of AFG-90H epoxy resin into a double planetary mixer and gradually heat it to 80°C with stirring. Add 316 g of 4,4-methylenebis(3-chloro-2,6-diethyl)aniline (MCDEA) in batches. Control the material temperature at 80°C and remove bubbles under vacuum until transparent. Then cool the mixture for later use. This is recorded as component A.

[0051] The ratio of the molar number of all epoxy resins in the raw materials to the molar number of curing agent MCDEA is 100:100.

[0052]

[0053] 4,4-Methylenebis(3-chloro-2,6-diethyl)aniline (MCDEA)

[0054] Components A and B are mixed uniformly at a temperature of approximately 85°C and vacuumed for 30-60 minutes to remove a small amount of air introduced during the addition and stirring process. Finally, the mixture is discharged and packaged to obtain a single-component liquid molding resin composition 1 with a long window period and high toughness.

[0055] Example 2

[0056] 118g of TDE-85 epoxy resin, 118g of AG-80 epoxy resin, and 170g of NPEF-170 epoxy resin were added to a double planetary mixer and stirred and gradually heated to about 80°C. 12g of polyethersulfone (PES) was added in batches and the temperature was gradually increased to 120°C. The bubbles were removed by vacuum until the mixture became transparent, and then cooled and set aside. This was recorded as component B.

[0057] Add 98g AFG-90MH resin and 118g TDE-85 resin into a double planetary mixer, stir and gradually heat to 80℃, add 348g MCDEA in batches, control the material temperature at 80℃, remove bubbles in vacuum until transparent, then cool and set aside, recorded as component A.

[0058] The ratio of the molar number of all epoxy resins in the raw materials to the molar number of curing agent MCDEA is 88:100.

[0059] Components A and B are mixed uniformly at a temperature of approximately 85°C and vacuumed for 30-60 minutes to remove any air introduced during the addition and stirring process. Finally, the mixture is discharged and packaged to obtain a single-component liquid molding resin composition 2 with a long molding window and high toughness.

[0060] Example 3

[0061] 130g AG-70 epoxy resin and 170g NPEF-170 epoxy resin were added to a double planetary mixer, stirred and gradually heated to about 80°C, 46g nylon was added in batches, and the temperature was gradually increased to 120°C. The bubbles were removed by vacuum until the material became transparent, and then cooled and set aside. This was recorded as component B.

[0062] Add 96g AFG-90H epoxy resin and 118g TDE-85 epoxy resin into a double planetary mixer, stir and gradually heat to 80℃, add 300g MCDEA in batches, control the material temperature at 80℃, remove bubbles in vacuum until transparent, then cool and set aside, recorded as component A.

[0063] The ratio of the molar number of all epoxy resins in the raw materials to the molar number of curing agent MCDEA is 95:100.

[0064] Components A and B were mixed uniformly at approximately 85°C and vacuumed for 30-60 minutes to remove any air introduced during the addition and stirring process. Finally, the mixture was discharged and packaged to obtain a single-component liquid molding resin composition 3 with a long molding window and high toughness.

[0065] Example 4

[0066] 195g AG-70 epoxy resin, 118g AG-80 epoxy resin and 85g NPEF-170 epoxy resin were added to a double planetary mixer and stirred and gradually heated to about 80°C. 38g polyethersulfone (PES) was added in batches and the temperature was gradually increased to 120°C. The bubbles were removed by vacuum until the mixture became transparent and then cooled for later use. This was recorded as component B.

[0067] Add 144g AFG-90H epoxy resin into a double planetary mixer, stir and gradually heat up to 80℃, add 320g MCDEA in batches, control the material temperature at 80℃, remove bubbles in vacuum until transparent, then cool and set aside, recorded as component A.

[0068] The ratio of the molar number of all epoxy resins in the raw materials to the molar number of the curing agent MCDEA is 90:100.

[0069] Components A and B are mixed uniformly at a temperature of approximately 85°C and vacuumed for 30-60 minutes to remove any air introduced during the addition and stirring process. Finally, the mixture is discharged and packaged to obtain a single-component liquid molding resin composition 4 with a long molding window and high toughness.

[0070] Example 5

[0071] 196 g AFG-90MH epoxy resin, 118 g AG-80 epoxy resin, and 85 g NPEF-170 epoxy resin were added to a double planetary mixer and stirred. The temperature was gradually raised to about 80°C. 30 g polyethersulfone (PES) was added in batches and the temperature was gradually raised to 120°C. The bubbles were removed by vacuum until the mixture became transparent, and then cooled for later use. This was recorded as component B.

[0072] Add 192g of AFG-90H epoxy resin into a double planetary mixer and gradually heat it to 80°C while stirring. Add 368.5g of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) in batches. Control the material temperature at 80°C and remove bubbles in a vacuum. After the mixture becomes transparent, cool it and set aside. This is recorded as component A.

[0073]

[0074] 3,3'-Dichloro-4,4'-diaminodiphenylmethane (MOCA)

[0075] The ratio of the molar number of all epoxy resins in the raw materials to the molar number of the curing agent MOCA is 100:100.

[0076] Components A and B are mixed uniformly at a temperature of approximately 85°C and vacuumed for 30-60 minutes to remove any air introduced during the addition and stirring process. Finally, the mixture is discharged and packaged to obtain a single-component liquid molding resin composition 5 with a long molding window and high toughness.

[0077] Example 6

[0078] 98g AFG-90MH epoxy resin, 59g AG-80 epoxy resin, and 85g NPEF-175 epoxy resin were added to a double planetary mixer and stirred. The temperature was gradually raised to about 80°C. 27g polyaryletherketone (PEKK) was added in batches and the temperature was gradually raised to 120°C. The bubbles were removed by vacuum until the mixture became transparent, and then cooled for later use. This was recorded as component B.

[0079] Add 144g of AFG-90H epoxy resin into a double planetary mixer and gradually heat it to 80°C while stirring. Add 258g of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) in batches. Control the material temperature at 80°C and remove bubbles in a vacuum. After cooling until transparent, set aside. This is recorded as component A.

[0080] The ratio of the molar number of all epoxy resins in the raw materials to the molar number of the curing agent MOCA is 110:100.

[0081] Components A and B are mixed uniformly at approximately 85°C and vacuumed for 30-60 minutes to remove any air introduced during the addition and stirring process. Finally, the mixture is discharged and packaged to obtain a single-component liquid molding resin composition 6 with a long molding window and high toughness.

[0082] Example 7

[0083] 130 g AFG-70 epoxy resin, 54 g AG-90 epoxy resin, and 90 g NPEF-180 epoxy resin were added to a double planetary mixer and stirred. The temperature was gradually raised to about 80°C. 28 g polyetheretherketone (PEEK) was added in batches and the temperature was gradually raised to 120°C. The bubbles were removed by vacuum until the mixture became transparent, and then cooled for later use. This was recorded as component B.

[0084] Add 288g of TDE-85 epoxy resin to a double planetary mixer and gradually heat it to 80°C while stirring. Add 352g of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) in batches. Control the material temperature at 80°C and remove bubbles in a vacuum. After cooling until transparent, set aside. This is recorded as component A.

[0085] The ratio of the molar number of all epoxy resins in the raw materials to the molar number of the curing agent MOCA is 105:100.

[0086] Components A and B are mixed uniformly at approximately 85°C and vacuumed for 30-60 minutes to remove any air introduced during the addition and stirring process. Finally, the mixture is discharged and packaged to obtain a single-component liquid molding resin composition 7 with a long molding window and high toughness.

[0087] Example 8

[0088] 65 g AFG-70 epoxy resin, 59 g AG-80 epoxy resin, and 85 g NPEF-170 epoxy resin were added to a double planetary mixer and stirred. The temperature was gradually raised to about 80°C. 18 g polyethersulfone (PES) was added in batches and the temperature was gradually raised to 120°C. The bubbles were removed by vacuum until the mixture became transparent, and then cooled for later use. This was recorded as component B.

[0089] 384 g of AFG-90H epoxy resin was added to a double planetary mixer, and the temperature was gradually raised to 80°C while stirring. 368.5 g of MOCA was added in batches, and the material temperature was controlled at 80°C. The bubbles were removed by vacuum until transparent, and then cooled for later use. This was recorded as component A.

[0090] The ratio of the molar number of all epoxy resins in the raw materials to the molar number of the curing agent MOCA is 100:100.

[0091] Components A and B were mixed uniformly at approximately 85°C and vacuumed for 30-60 minutes to remove any air introduced during the addition and stirring process. Finally, the mixture was discharged and packaged to obtain a single-component liquid molding resin composition 8 with a long molding window and high toughness.

[0092] Comparative Example 1

[0093] Except that the curing agent was replaced by 2,6-diaminonaphthalene instead of MCDEA, everything else was the same as in Example 1. A control resin 1 was obtained.

[0094] Comparative Example 2

[0095] Except that the curing agent was replaced by 3,3-diethyl-4,4-diaminodiphenylmethane (MOEA) without a chlorine electron-withdrawing group, the other steps were the same as those in Example 6. A control resin 2 was obtained.

[0096]

[0097] 3,3-Diethyl-4,4-diaminodiphenylmethane (MOEA)

[0098] Comparative Example 3

[0099] The types and amounts of raw materials in this comparative example are the same as those in Example 1, but the order of adding the materials is different. The specific preparation method is as follows:

[0100] 98g AFG-90MH epoxy resin, 59g AG-80 epoxy resin, 192g AFG-90H epoxy resin and 85g NPEF-170 epoxy resin were added to a double planetary mixer in sequence, and the temperature was gradually increased to about 80°C. 45g nylon was added in batches, and the temperature was gradually increased to control the material temperature at 120°C. The bubbles were removed by vacuum until the material was uniform and transparent, and then gradually cooled to about 85°C.

[0101] Then, 316 g of 4,4-methylenebis(3-chloro-2,6-diethyl)aniline (MCDEA) was added in batches. The material temperature was controlled at approximately 85 ± 2°C and stirred until the material became homogeneous and transparent. Vacuum was used to remove bubbles during the entire process. Control resin 3 was obtained.

[0102] Example 9

[0103] The tensile strength, tensile modulus, elongation at break, flexural strength, and flexural modulus of the one-component liquid molding resin compositions obtained in Examples 1-8 and Comparative Examples 1-3, respectively, were tested according to GB / T 2567. The glass transition temperature was tested according to ASTM D 7028 (Tan Peak Temperature). The experimental results are shown in Table 1.

[0104] Table 1

[0105]

[0106] *The process operation period (window period) refers to the time during which the resin viscosity is maintained ≤300mPa.s at 100°C.

[0107] As can be seen from Table 1, the one-component liquid molding resin composition 1-8 prepared by Example 1-8 has a window period of 7.5-9.8 hours, which can meet the preparation requirements of large-scale composite materials. Comparative Example 1 uses a curing agent that does not contain a chlorine electron-withdrawing group, and the resin window period of its preparation is only 4.5 hours, while the one-component liquid molding resin composition window period prepared by Example 1 can reach 9.8 hours. Comparative Example 2 uses a curing agent that does not contain a chlorine electron-withdrawing group, and the one-component liquid molding resin composition window period of its preparation is only 4 hours, while the one-component liquid molding resin composition window period prepared by Example 6 can reach 8 hours. As can be seen from the control experiment of Comparative Example 1-2, the present invention significantly prolongs the window period of the gained one-component liquid molding resin composition by introducing a chlorine electron-withdrawing group in the ortho or para position into the aromatic amine curing agent.

[0108] As can be seen from Table 1, the one-component liquid molding resin composition 1-8 prepared in Examples 1-8 is a matrix resin with a wide window period, high toughness, and high heat resistance, and is suitable for the needs of manufacturing the main load-bearing structure of civil aviation composite materials using dry fiber automatic placement liquid molding technology.

[0109] The bending strength of the resin prepared in Comparative Example 3 is 148 MPa, while the bending strength of the resin prepared in Example 1 using the method of the present invention is 165 MPa. It can be seen that the present invention adopts the method of dissolving the curing agent and the toughening agent separately, changing the addition order, and the bending strength of the resin is increased by 11%. At the same time, the operating window period is shortened to 6.0 hours.

[0110] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A one-component liquid molding resin composition, characterized in that: The composition includes the following weight percentages: The toughening agent is a thermoplastic resin; The low-activity curing agent is an aromatic amine curing agent with a chlorine-containing electron-withdrawing group introduced into the ortho-position or para-position of the amino group; The ratio of the mole number of the low-activity curing agent to the total mole number of the tetrafunctional epoxy resin, the trifunctional epoxy resin and the bifunctional epoxy resin is (88-110):

100.

2. The one-component liquid molding resin composition according to claim 1, characterized in that: The tetrafunctional epoxy resin is selected from one or two of 4,4'-diaminodiphenylmethane tetraglycidylamine epoxy resin and 3,3'-diethyl-4,4'-diaminodiphenylmethane tetraglycidylamine; the epoxy equivalent of the tetrafunctional epoxy resin is 118-130 g / mol.

3. The one-component liquid molding resin composition according to claim 1, characterized in that: The trifunctional epoxy resin is selected from one or more of p-aminophenol triglycidyl epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester; the epoxy equivalent of the trifunctional epoxy resin is 96-118 g / mol.

4. The one-component liquid molding resin composition according to claim 1, characterized in that: The bifunctional epoxy resin is selected from bisphenol F type epoxy resin; the epoxy equivalent of the bifunctional epoxy resin is 160-190 g / mol.

5. The one-component liquid molding resin composition according to claim 4, characterized in that: The bisphenol F type epoxy resin is selected from one or more of NPEF-170 epoxy resin, NPEF-175 epoxy resin and NPEF-180 epoxy resin.

6. The one-component liquid molding resin composition according to claim 1, characterized in that: The thermoplastic resin is selected from one or more of polyethersulfone, nylon, polyetheretherketone and polyaryletherketone.

7. The one-component liquid molding resin composition according to claim 1, characterized in that: The low-activity curing agent is selected from one or more of 4,4'-methylene-bis-(3-chloro-2,6-diethylaniline) and 3,3'-dichloro-4,4'-diaminodiphenylmethane.

8. A method for preparing the one-component liquid molding resin composition according to claims 1-7, characterized in that: The following steps are involved: S1, taking a trifunctional epoxy resin with a mass of 1-1.8 times that of a low-activity curing agent, stirring and heating to 80° C., adding the low-activity curing agent, mixing at 80° C., vacuum degassing until transparent, and cooling to obtain component A; S2, mixing all the tetrafunctional epoxy resin, the difunctional epoxy resin and the remaining trifunctional epoxy resin at 75-85° C., adding a toughening agent, mixing at 120° C., vacuum degassing until transparent, and then cooling to obtain component B; S3, mixing component A and component B at 80-90° C., and vacuuming for 30-60 minutes to remove air to obtain a single-component liquid molding resin composition; There is no order of precedence for steps S1 and S2.

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