A carbon fiber prepreg with high low-temperature stability

Abstract

The present invention provides a carbon fiber prepreg with high low-temperature stability, relates to the technical field of composite materials, including a resin matrix and a carbon fiber; the resin matrix includes the following raw materials in parts by weight: 83‑87 parts of epoxy acrylate, 10‑14 parts of polycaprolactone, 1.0‑1.4 parts of triethylamine, 1.5‑2.1 parts of initiator, and 200 parts of solvent; the weight ratio of the resin matrix to the carbon fiber is 30‑40:60‑70. During the preparation process of the carbon fiber prepreg, the introduction of ether bonds and hydroxyl groups forms flexible segments, improves the toughness of the resin matrix, and makes the resin specifically have higher low-temperature impact resistance; and the chemical bonding effect can reduce the phase separation of the resin matrix, thereby being able to improve its interlaminar shear strength. The carbon fiber prepreg has the advantages of stable interface and high impact resistance under low-temperature conditions, making the carbon fiber prepreg more stable at low temperatures.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a carbon fiber prepreg with high low-temperature stability. Background Art

[0002] Carbon fiber prepreg is a material formed by combining carbon fiber and epoxy resin under high temperature and high pressure. It is an intermediate material in the manufacture of composite materials. Therefore, the quality of carbon fiber prepreg is closely related to the quality of the composite material. Carbon fiber prepreg has the advantages of light weight and high strength. It is widely used in the fields of aerospace, sports equipment, firefighting equipment, and industrial equipment. As the application fields of carbon fiber prepreg expand, the performance requirements for carbon fiber prepreg are also becoming increasingly higher.

[0003] The resin matrix is one of the raw materials of carbon fiber prepreg. When the ambient temperature drops, the resin matrix is prone to embrittlement and interface debonding, which can easily lead to a decrease in the impact resistance of the carbon fiber prepreg and interface fracture, resulting in cracks and other problems, affecting the mechanical properties of the carbon fiber prepreg.

[0004] Therefore, it is of great significance to provide a carbon fiber prepreg that can maintain interface stability and stable mechanical properties at low temperatures. Summary of the Invention

[0005] In light of this, the present invention provides a carbon fiber prepreg with high low-temperature stability. Specifically, the prepreg is a composite of carbon fibers and a resin matrix prepared from epoxy acrylate and polycaprolactone in the presence of triethylamine catalyst. This prepreg exhibits low-temperature interfacial stability and high impact resistance, making it more stable at low temperatures.

[0006] The technical solutions of the present invention are as follows:

[0007] A carbon fiber prepreg with high low-temperature stability, comprising a resin matrix and carbon fibers;

[0008] The resin matrix comprises the following raw materials in parts by weight:

[0009] 83-87 parts of epoxy acrylate, 10-14 parts of polycaprolactone, 1.0-1.4 parts of triethylamine, 1.5-2.1 parts of initiator, and 200 parts of solvent;

[0010] The weight ratio of the resin matrix to the carbon fiber is 30-40:60-70.

[0011] Preferably, the resin matrix comprises the following raw materials in parts by weight:

[0012] 86 parts of epoxy acrylate, 11 parts of polycaprolactone, 1.1 parts of triethylamine, 1.9 parts of initiator, and 200 parts of solvent.

[0013] Preferably, the number average molecular weight of the polycaprolactone is 2000-4000; the initiator is a UV initiator; and the solvent is one of tetrahydrofuran and acetone.

[0014] Preferably, the resin matrix is prepared as follows:

[0015] S1, pre-mixing, adding epoxy acrylate and polycaprolactone into a reaction kettle, then adding solvent, stirring until completely dissolved to obtain a solution for standby use;

[0016] This process allows epoxy acrylate and polycaprolactone to be fully dissolved in the solvent, ensuring that they are evenly distributed in the solution. Under the action of stirring, the gas in the solution can also be removed, providing a good liquid environment for subsequent reactions and reducing the probability of material defects in the resin matrix.

[0017] Epoxy acrylate is a modified resin obtained by esterification of epoxy resin and acrylic acid. It has good toughness and viscosity and can provide epoxy groups and double bonds for the reaction.

[0018] Polycaprolactone is a high molecular weight polymer obtained by ring-opening polymerization of ε-caprolactone. It has high flexibility and low glass transition temperature, and can provide ester groups and hydroxyl groups for the reaction.

[0019] S2, adding triethylamine to the solution, stirring and reacting for 1.5-2.5 hours to obtain reaction solution A;

[0020] The epoxy group is a three-membered ring structure. When triethylamine is used as a catalyst, it can significantly reduce the tension of the epoxy ring, thereby facilitating the reaction between the hydroxyl groups of polycaprolactone and the carbon atoms in the epoxy group, achieving an efficient ring-opening reaction, resulting in ring scission and the formation of new chemical bonds, including ether bonds and hydroxyl groups. The hydroxyl groups after ring opening can, on the one hand, undergo condensation reactions with the hydroxyl groups of polycaprolactone to form ether bonds or ester bonds, further strengthening the crosslinking between polymer chains. On the other hand, they can undergo exchange reactions with the ester groups of polycaprolactone, resulting in polymer chain reorganization or the formation of new ester bonds. The ether bonds after ring opening can also undergo coupling reactions, forming a more complex network.

[0021] In the resin matrix, the epoxy acrylate and polycaprolactone are chemically bonded to form an interpenetrating network structure, which gives the resulting resin matrix good toughness and improves its ability to absorb impact energy under low-temperature conditions. Under the catalysis of triethylamine, the epoxy groups, after ring opening, mainly form ether bonds with the hydroxyl groups of the polycaprolactone, and form a cross-linked network through ester exchange and / or condensation reactions, which improves the bonding ability, makes the resin matrix more stable, and reduces the probability of cracking at low temperatures.

[0022] S3, adding an initiator to the reaction solution A, stirring at room temperature for 25-35 minutes, and then performing vacuum degassing to obtain a reaction solution B;

[0023] The addition of initiator can trigger the free polymerization of unreacted acrylate double bonds in the subsequent curing process to form a cross-linked network, further increasing the cross-linking degree of the resin matrix, thereby making the resin matrix strong and tough at low temperatures and improving its impact resistance;

[0024] S4, concentrating the reaction solution B by vacuum concentration until the solution viscosity reaches 900-1200 mPa·s (25° C.), thereby obtaining a resin matrix;

[0025] By concentrating under reduced pressure, the solvent content in the resin matrix can be reduced, thereby avoiding problems such as weakening of the resin matrix interface caused by the solvent and allowing the resin matrix to maintain good strength.

[0026] Preferably, in step S1, the stirring process is carried out at 55-65°C; the stirring speed is 50-60 rpm, and the stirring time is 30-40 min.

[0027] Preferably, in step S2, the stirring process is carried out at 60-65°C and the stirring speed is 30-40 rpm.

[0028] Preferably, in step S4, the reduced pressure concentration is performed at 45-50°C.

[0029] Preferably, the carbon fiber prepreg is prepared as follows:

[0030] Step 1: Place the resin matrix in an immersion tank, adjust the viscosity of the resin matrix to 400-450mPa.s (25°C), and control the liquid temperature in the immersion tank to 55±1°C;

[0031] Step 2: introduce the carbon fiber cloth into the impregnation tank, control the surface tension of the carbon fiber cloth to 30-40N / m, and make the carbon fiber cloth enter the impregnation tank stably, thereby ensuring that the resin can stably enter the carbon fiber cloth and improve the stability of the quality of the carbon fiber prepreg;

[0032] Control the carbon fiber cloth to be completely immersed in the resin matrix liquid, and the carbon fiber cloth passes through the impregnation tank at a speed of 1.0-1.5m / min;

[0033] Step 3: Use a roller pressing device to process the impregnated carbon fiber cloth at a roller pressing pressure of 0.15-0.2 MPa;

[0034] The roller pressing process is used to eliminate bubbles and make the combination of the resin matrix and the carbon fiber cloth more uniform;

[0035] Step 4: The rolled carbon fiber cloth is dried with hot air at a temperature of 80-85°C to initially lock the resin matrix and the carbon fiber to prevent resin flow during the curing process.

[0036] Step five: UV curing to enable rapid chain polymerization of the acrylate double bonds to form a cross-linked network and fix the fiber-resin interface;

[0037] Thermal curing: maintain at 75±1℃ for 0.5-1h, then increase the temperature and maintain at 110±1℃ for 2-2.5h; eliminate the internal stress generated by UV curing, enhance the interface bonding, and form epoxy crosslinking;

[0038] Step six: After natural cooling, a carbon fiber prepreg is obtained.

[0039] Preferably, in step 2, before the carbon fiber cloth enters the impregnation tank, compressed air is used to clean the surface of the carbon fiber cloth to remove fiber impurities on the surface, so that the carbon fiber cloth can be better combined with the resin matrix, thereby improving the quality of the carbon fiber prepreg cloth.

[0040] Preferably, in step 5, the UV curing light source is a 365nm UV lamp with an irradiation intensity of 30-40Mw / cm 2 , the irradiation time is 5-7min, the irradiation distance is 10-15cm, and the curing uniformity is improved.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. In the present invention, under the condition of triethylamine as a catalyst, the epoxy group provided by epoxy acrylate and the ester group and hydroxyl group provided by polycaprolactone are bonded to form a resin matrix with a cross-linked network structure; wherein, the introduction of ether bonds and hydroxyl groups forms flexible chain segments, improves the toughness of the resin matrix, and makes the resin have higher low-temperature impact resistance; and the chemical bonding effect can reduce the phase separation of the resin matrix, thereby improving its interlaminar shear strength.

[0043] 2. The carbon fiber prepreg provided by the present invention controls the viscosity of the resin matrix and the passing speed of the carbon fiber cloth when the carbon fiber cloth is impregnated in the resin matrix, so that the resin matrix on the carbon fiber cloth is more evenly distributed. Therefore, during UV curing, a cross-linked network can be formed around the carbon fibers, making the interface bonding between the carbon fibers and the resin matrix tighter. After further thermal curing treatment, the epoxy crosslinks that continue to form can strengthen the interfacial bonding force, so that the carbon fiber prepreg has good impact resistance and interface stability at low temperatures, effectively avoiding problems such as cracking at low temperatures, and making the carbon fiber prepreg have the advantage of low-temperature stability and good application prospects. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0045] In the following examples and comparative examples of the present invention, epoxy acrylate (epoxy acrylate resin, EA) is EBECRYL 605 / 20; carbon fiber cloth, T700 grade, 12K tow, single layer density is 200g / m 2 ; The initiator is BASF photoinitiator 184.

[0046] Example 1

[0047] A carbon fiber prepreg with high low-temperature stability, comprising a resin matrix and carbon fibers;

[0048] The resin matrix includes the following raw materials in parts by weight:

[0049] 86 parts of epoxy acrylate, 11 parts of polycaprolactone, 1.1 parts of triethylamine, 1.9 parts of initiator, and 200 parts of solvent;

[0050] The number average molecular weight of polycaprolactone is 3000; the solvent is tetrahydrofuran;

[0051] The preparation process of the resin matrix is as follows:

[0052] S1, pre-mixing, adding epoxy acrylate and polycaprolactone into a reaction kettle, then adding solvent, stirring until completely dissolved to obtain a solution for standby use;

[0053] The stirring process was carried out at 60°C, the stirring speed was 55 rpm, and the stirring time was 35 min.

[0054] S2, adding triethylamine to the solution, and continuing to stir and react at 63°C and a stirring speed of 35 rpm for 2 h to obtain reaction solution A;

[0055] S3, adding an initiator to the reaction solution A, stirring at room temperature for 30 min at a stirring speed of 25 rpm, and then performing vacuum degassing to obtain a reaction solution B;

[0056] S4, concentrating the reaction solution B at 48°C by vacuum concentration until the solution viscosity reaches 1000 mPa.s (25°C), thereby obtaining a resin matrix;

[0057] The above-mentioned carbon fiber prepreg is prepared as follows:

[0058] Step 1: Place the resin matrix in an immersion tank, adjust the viscosity of the resin matrix to 425mPa.s (25°C), and control the liquid temperature in the immersion tank to 55°C;

[0059] Step 2: introduce the carbon fiber cloth into the impregnation tank, control the surface tension of the carbon fiber cloth to 35N / m, and use compressed air to clean the surface of the carbon fiber cloth before it enters the impregnation tank;

[0060] The carbon fiber cloth is completely immersed in the resin matrix liquid, and the carbon fiber cloth passes through the impregnation tank at a speed of 1.3m / min;

[0061] Step 3: Use a roller pressing device to process the impregnated carbon fiber cloth at a roller pressing pressure of 0.18 MPa;

[0062] Step 4: The rolled carbon fiber cloth is dried with hot air at a temperature of 82°C to initially lock the resin matrix and the carbon fiber to prevent resin flow during the curing process.

[0063] Step 5: UV curing, the light source is a 365nm UV lamp, the irradiation intensity is 35Mw / cm 2 , the irradiation time is 6 minutes, the irradiation distance is 12 cm, and the curing uniformity is improved; UV curing enables the acrylate double bonds to quickly chain polymerize, forming a cross-linked network and fixing the fiber resin interface;

[0064] Thermal curing: maintain at 75°C for 40 minutes, then increase the temperature and maintain at 110°C for 2 hours; eliminate the internal stress generated by UV curing, enhance the interface bonding, and form epoxy crosslinking;

[0065] Step six: After natural cooling, a carbon fiber prepreg is obtained; in the carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber cloth is 35:65.

[0066] Comparative Example 1

[0067] The difference from Example 1 is that epoxy resin is used instead of epoxy acrylate; the rest is the same as Example 1; in the obtained carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber cloth is 32:68.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that during the preparation of the carbon fiber prepreg,

[0070] Step 1: Place the resin matrix in an immersion tank, adjust the viscosity of the resin matrix to 395mPa.s (25°C), and control the liquid temperature in the immersion tank to 55°C;

[0071] Step 2: introduce the carbon fiber cloth into the impregnation tank, control the surface tension of the carbon fiber cloth to 35N / m, and use compressed air to clean the surface of the carbon fiber cloth before it enters the impregnation tank;

[0072] The carbon fiber cloth is completely immersed in the resin matrix liquid, and the carbon fiber cloth passes through the impregnation tank at a speed of 0.9m / min;

[0073] The rest is the same as in Example 1;

[0074] In the obtained carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber cloth is 26:74.

[0075] Comparative Example 3

[0076] The difference from Example 1 is that during the preparation of the carbon fiber prepreg,

[0077] Step 1: Place the resin matrix in an immersion tank, adjust the viscosity of the resin matrix to 460mPa.s (25°C), and control the liquid temperature in the immersion tank to 55°C;

[0078] Step 2: introduce the carbon fiber cloth into the impregnation tank, control the surface tension of the carbon fiber cloth to 35N / m, and use compressed air to clean the surface of the carbon fiber cloth before it enters the impregnation tank;

[0079] The carbon fiber cloth is completely immersed in the resin matrix liquid, and the carbon fiber cloth passes through the impregnation tank at a speed of 2.0m / min;

[0080] The rest is the same as in Example 1;

[0081] In the obtained carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber cloth is 45:55.

[0082] Comparative Example 4

[0083] The difference from Example 1 is that during the preparation of the carbon fiber prepreg,

[0084] Step 5: UV curing is the same as in Example 1;

[0085] Thermal curing: maintain at 110℃ for 3h;

[0086] The rest was the same as in Example 1; in the obtained carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber cloth was 34:66.

[0087] Example 2

[0088] A carbon fiber prepreg with high low-temperature stability, comprising a resin matrix and carbon fibers;

[0089] The resin matrix includes the following raw materials in parts by weight:

[0090] 83 parts of epoxy acrylate, 14 parts of polycaprolactone, 1.0 part of triethylamine, 2.0 parts of initiator, and 200 parts of solvent;

[0091] The number average molecular weight of polycaprolactone is 3000; the solvent is tetrahydrofuran;

[0092] The preparation process of the resin matrix is as follows:

[0093] S1, pre-mixing, adding epoxy acrylate and polycaprolactone into a reaction kettle, then adding solvent, stirring at 55°C until completely dissolved to obtain a solution for standby use;

[0094] Among them, the stirring speed is 50 rpm and the stirring time is 40 min;

[0095] S2, adding triethylamine to the solution, and continuing to stir and react at 60°C and a stirring speed of 30 rpm for 2.5 h to obtain reaction solution A;

[0096] S3, adding an initiator to the reaction solution A, stirring at room temperature for 25 min at a stirring speed of 25 rpm, and then performing vacuum degassing to obtain reaction solution B;

[0097] S4, concentrating the reaction solution B at 45°C by vacuum concentration until the solution viscosity reaches 900 mPa.s (25°C), thereby obtaining a resin matrix;

[0098] The above-mentioned carbon fiber prepreg is prepared as follows:

[0099] Step 1: Place the resin matrix in an immersion tank, adjust the viscosity of the resin matrix to 400 mPa.s (25°C), and control the liquid temperature in the immersion tank to 54°C;

[0100] Step 2: introduce the carbon fiber cloth into the impregnation tank, control the surface tension of the carbon fiber cloth to 30N / m, and use compressed air to clean the surface of the carbon fiber cloth before it enters the impregnation tank;

[0101] The carbon fiber cloth is completely immersed in the resin matrix liquid, and the carbon fiber cloth passes through the impregnation tank at a speed of 1.0m / min;

[0102] Step 3: Use a roller pressing device to process the impregnated carbon fiber cloth at a roller pressing pressure of 0.15 Pa;

[0103] Step 4: The rolled carbon fiber cloth is dried with hot air at a temperature of 85°C to initially lock the resin matrix and the carbon fiber to prevent resin flow during the curing process.

[0104] Step 5: UV curing, the light source is a 365nm UV lamp, the irradiation intensity is 30Mw / cm 2, the irradiation time is 7min, and the irradiation distance is 15cm;

[0105] Thermal curing: maintain at 74°C for 1 hour, then increase the temperature and maintain at 109°C for 2.5 hours; eliminate the internal stress generated by UV curing, enhance the interface bonding, and form epoxy crosslinking;

[0106] Step six: After natural cooling, a carbon fiber prepreg is obtained; in the carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber cloth is 30:70.

[0107] Example 3

[0108] A carbon fiber prepreg with high low-temperature stability, comprising a resin matrix and carbon fibers;

[0109] The resin matrix includes the following raw materials in parts by weight:

[0110] 87 parts of epoxy acrylate, 10 parts of polycaprolactone, 1.4 parts of triethylamine, 1.6 parts of initiator, and 200 parts of solvent;

[0111] The number average molecular weight of polycaprolactone is 3000; the solvent is tetrahydrofuran;

[0112] The preparation process of the resin matrix is as follows:

[0113] S1, pre-mixing, adding epoxy acrylate and polycaprolactone into a reaction kettle, then adding solvent, stirring at 65°C and a stirring speed of 60 rpm until completely dissolved, stirring time is 30 minutes, to obtain a solution, set aside;

[0114] S2, adding triethylamine to the solution, and continuing to stir and react at 65°C and a stirring speed of 40 rpm for 1.5 h to obtain reaction solution A;

[0115] S3, adding an initiator to the reaction solution A, stirring at room temperature for 35 minutes at a stirring speed of 25 rpm, and then performing vacuum degassing to obtain a reaction solution B;

[0116] S4, concentrating the reaction solution B at 50° C. by vacuum concentration until the solution viscosity reaches 1200 mPa·s (25° C.), thereby obtaining a resin matrix;

[0117] The above-mentioned carbon fiber prepreg is prepared as follows:

[0118] Step 1: Place the resin matrix in an immersion tank, adjust the viscosity of the resin matrix to 450 mPa.s (25°C), and control the liquid temperature in the immersion tank to 56°C;

[0119] Step 2: introduce the carbon fiber cloth into the impregnation tank, control the surface tension of the carbon fiber cloth to 40N / m, and use compressed air to clean the surface of the carbon fiber cloth before it enters the impregnation tank;

[0120] The carbon fiber cloth is completely immersed in the resin matrix liquid, and the carbon fiber cloth passes through the impregnation tank at a speed of 1.5m / min;

[0121] Step 3: Use a roller pressing device to process the impregnated carbon fiber cloth at a roller pressing pressure of 0.2 MPa;

[0122] Step 4: The rolled carbon fiber cloth is dried with hot air at a temperature of 80°C to initially lock the resin matrix and the carbon fiber to prevent resin flow during the curing process.

[0123] Step 5: UV curing, the light source is a 365nm UV lamp, the irradiation intensity is 40Mw / cm 2 , the irradiation time is 5min, and the irradiation distance is 10cm;

[0124] Thermal curing: maintain at 76°C for 0.5h, then increase the temperature and maintain at 111°C for 2h; eliminate the internal stress generated by UV curing, enhance the interface bonding, and form epoxy crosslinking;

[0125] Step six: After natural cooling, a carbon fiber prepreg is obtained. In the carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber cloth is 40:60.

[0126] Example 4

[0127] A carbon fiber prepreg with high low-temperature stability, comprising a resin matrix and carbon fibers;

[0128] The resin matrix comprises the following raw materials in parts by weight:

[0129] 85 parts of epoxy acrylate, 12 parts of polycaprolactone, 1.3 parts of triethylamine, 1.7 parts of initiator, and 200 parts of solvent;

[0130] The number average molecular weight of polycaprolactone is 2000; the solvent is tetrahydrofuran;

[0131] The preparation process of the resin matrix is as follows:

[0132] S1, pre-mixing, adding epoxy acrylate and polycaprolactone into a reaction kettle, then adding solvent, stirring at 60°C and 50 rpm until completely dissolved, stirring time is 35 minutes, to obtain a solution for standby use;

[0133] S2, adding triethylamine to the solution, stirring at 60°C and 40 rpm for 2.3 h to obtain reaction solution A;

[0134] S3, adding an initiator to the reaction solution A, stirring at room temperature for 30 min at a stirring speed of 25 rpm, and then performing vacuum degassing to obtain a reaction solution B;

[0135] S4, concentrating the reaction solution B at 50° C. by vacuum concentration until the solution viscosity reaches 1100 mPa·s (25° C.), thereby obtaining a resin matrix;

[0136] The above-mentioned carbon fiber prepreg is prepared as follows:

[0137] Step 1: Place the resin matrix in an immersion tank, adjust the viscosity of the resin matrix to 440 mPa.s (25°C), and control the liquid temperature in the immersion tank to 55°C;

[0138] Step 2: introduce the carbon fiber cloth into the impregnation tank, control the surface tension of the carbon fiber cloth to 38N / m, and use compressed air to clean the surface of the carbon fiber cloth before it enters the impregnation tank;

[0139] The carbon fiber cloth is completely immersed in the resin matrix liquid, and the carbon fiber cloth passes through the impregnation tank at a speed of 1.2m / min;

[0140] Step 3: Use a roller pressing device to process the impregnated carbon fiber cloth at a roller pressing pressure of 0.2 MPa;

[0141] Step 4: The rolled carbon fiber cloth is dried with hot air at a drying temperature of 82°C.

[0142] Step 5: UV curing, the light source is a 365nm UV lamp, the irradiation intensity is 35Mw / cm 2 , the irradiation time was 6 min and the irradiation distance was 12 cm;

[0143] Thermal curing: maintain at 75°C for 50 minutes, then increase the temperature and maintain at 110°C for 2.5 hours; eliminate the internal stress generated by UV curing, enhance the interface bonding, and form epoxy crosslinking;

[0144] Step six: After natural cooling, a carbon fiber prepreg is obtained. In the carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber cloth is 37:63.

[0145] Example 5

[0146] A carbon fiber prepreg with high low-temperature stability, comprising a resin matrix and carbon fibers;

[0147] The resin matrix includes the following raw materials in parts by weight:

[0148] 84 parts of epoxy acrylate, 12.5 parts of polycaprolactone, 1.4 parts of triethylamine, 2.1 parts of initiator, and 200 parts of solvent;

[0149] The number average molecular weight of polycaprolactone is 4000; the solvent is tetrahydrofuran;

[0150] The preparation process of the resin matrix is as follows:

[0151] S1, pre-mixing, adding epoxy acrylate and polycaprolactone into a reaction kettle, then adding solvent, stirring at 58°C and a stirring speed of 55 rpm until completely dissolved, stirring time is 36 minutes, to obtain a solution for standby use;

[0152] S2, adding triethylamine to the solution, stirring at 62° C. and 35 rpm for 2 h to obtain reaction solution A;

[0153] S3, adding an initiator to the reaction solution A, stirring at room temperature for 33 minutes at a stirring speed of 25 rpm, and then performing vacuum degassing to obtain a reaction solution B;

[0154] S4, concentrating the reaction solution B at 47°C by vacuum concentration until the solution viscosity reaches 1000 mPa.s (25°C), thereby obtaining a resin matrix;

[0155] The above-mentioned carbon fiber prepreg is prepared as follows:

[0156] Step 1: Place the resin matrix in an immersion tank, adjust the viscosity of the resin matrix to 410 mPa.s (25°C), and control the liquid temperature in the immersion tank to 54°C;

[0157] Step 2: introduce the carbon fiber cloth into the impregnation tank, control the surface tension of the carbon fiber cloth to 35N / m, and use compressed air to clean the surface of the carbon fiber cloth before it enters the impregnation tank;

[0158] The carbon fiber cloth is completely immersed in the resin matrix liquid, and the carbon fiber cloth passes through the impregnation tank at a speed of 1.0m / min;

[0159] Step 3: Use a roller pressing device to process the impregnated carbon fiber cloth at a roller pressing pressure of 0.16 MPa;

[0160] Step 4: The rolled carbon fiber cloth is dried with hot air at a drying temperature of 85°C.

[0161] Step 5: UV curing, the light source is a 365nm UV lamp, the irradiation intensity is 33Mw / cm 2 , the irradiation time was 6 min and the irradiation distance was 11 cm;

[0162] Thermal curing: maintain at 75℃ for 50min, then increase the temperature and maintain at 110℃ for 2.5h;

[0163] Step six: After natural cooling, a carbon fiber prepreg is obtained. In the carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber cloth is 34:66.

[0164] Example 6

[0165] A carbon fiber prepreg with high low-temperature stability, which differs from Example 1 in that the solvent is acetone; the rest is the same as Example 1;

[0166] In the obtained carbon fiber prepreg, the weight ratio of the resin matrix to the carbon fiber is 32:68.

[0167] The carbon fiber prepregs obtained in Examples 1-6 and Comparative Examples 1-4 were tested at -40°C, as follows:

[0168] 1. Low-temperature impact resistance test: The carbon fiber prepregs obtained in the examples and comparative examples were made into specimens with a size of 80×10×4 mm, and the edges of the specimens were free of burrs. The specimens were kept at -40°C for 4 hours, then removed and tested according to ASTM D256 (Izod beam impact test). The results are shown in Table 1:

[0169] Table 1 Low temperature impact resistance test results

[0170]

[0171] Combined with Table 1, it can be seen that after treatment, the carbon fiber impregnated cloth provided by Examples 1-6 of the present invention has decreased, but still maintains a high impact resistance. This shows that in the carbon fiber impregnated cloth prepared by the method of the present invention, epoxy acrylate and polycaprolactone form a resin matrix with a cross-linked network structure under the catalysis of triethylamine, wherein the introduction of ether bonds and hydroxyl groups forms flexible chain segments, thereby improving the toughness of the resin matrix. Therefore, at low temperatures, when subjected to external force impact, it can effectively absorb energy, thereby improving the impact resistance of the carbon fiber prepreg.

[0172] 2. Tensile Strength Test: The carbon fiber prepregs obtained in the Examples and Comparative Examples were made into straight strip specimens with a size of 250 × 25 × 2 mm and marked with gauge lengths. The specimens were kept at -40°C for 4 hours, then removed and the corresponding tensile strengths were tested according to ASTM D3039. The results are shown in Table 2.

[0173] Table 2 Tensile strength test results

[0174]

[0175] 3. Bending Strength Test: The carbon fiber prepregs obtained in the Examples and Comparative Examples were made into specimens with a size of 80 × 10 × 4 mm. The specimens were kept at -40°C for 4 hours, then the specimens were taken out and the corresponding bending strength was tested according to ASTM D790. The results are shown in Table 3.

[0176] Table 3 Bending strength test results

[0177]

[0178] From Table 3 and Table 4, it can be seen that after treatment, the tensile strength and flexural strength of the carbon fiber prepreg provided by the present invention are both reduced to a certain extent compared to those under normal temperature conditions, but the degree of reduction is significantly lower than that of Comparative Examples 1-4. In other words, the carbon fiber prepreg provided by the present invention has good mechanical property stability under low temperature conditions, making it more suitable for use in low temperature environments.

[0179] 4. Interlaminar shear strength test: The carbon fiber prepregs obtained in the examples and comparative examples were made into specimens with a size of 20 × 6 × 2 mm. The specimens were kept at -40°C for 4 hours, then the specimens were taken out and the corresponding interlaminar shear strength was tested according to ASTM D2344. The results are shown in Table 4.

[0180] Table 4 Interlaminar shear strength test results

[0181]

[0182] As can be seen from Table 4, the carbon fiber prepreg provided by the present invention has good interlaminar shear strength at low temperatures, indicating that in the carbon fiber prepreg of the present invention, the bonding effect makes the interphase bonding strong, effectively reduces the problems such as phase separation, and makes the interface bonding between the carbon fiber cloth and the resin matrix more stable; in addition, the flexible chain segments introduced by the reaction effectively improve the toughness of the carbon fiber prepreg, and can avoid cracks when subjected to external force at low temperatures.

[0183] Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person skilled in the art who can easily conceive of changes or substitutions within the technical scope disclosed in the present invention shall be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection of the claims.

Claims

1. A carbon fiber prepreg with high low-temperature stability, comprising a resin matrix and carbon fibers; characterized in that: The resin matrix comprises the following raw materials in parts by weight: 83-87 parts of epoxy acrylate, 10-14 parts of polycaprolactone, 1.0-1.4 parts of triethylamine, 1.5-2.1 parts of initiator, and 200 parts of solvent; The weight ratio of resin matrix to carbon fiber is 30-40:60-70; The carbon fiber prepreg with high low-temperature stability is prepared as follows: Step 1: Place the resin matrix in an immersion tank, adjust the viscosity of the resin matrix to 400-450 mPa.s at 25°C, and control the liquid temperature in the immersion tank to 55±1°C; Step 2: introduce the carbon fiber cloth into the impregnation tank and control the surface tension of the carbon fiber cloth to 30-40N / m; Control the carbon fiber cloth to be completely immersed in the resin matrix liquid, and the carbon fiber cloth passes through the impregnation tank at a speed of 1.0-1.5m / min; Step 3: Use a roller pressing device to process the impregnated carbon fiber cloth at a roller pressing pressure of 0.15-0.2 MPa; Step 4: The rolled carbon fiber cloth is dried with hot air at a temperature of 80-85°C. Step five, UV curing; Thermal curing: maintain at 75±1℃ for 0.5-1h, then increase the temperature and maintain at 110±1℃ for 2-2.5h; Step six: After natural cooling, a carbon fiber prepreg is obtained.

2. The carbon fiber prepreg with high low-temperature stability according to claim 1, characterized in that The resin matrix comprises the following raw materials in parts by weight: 86 parts of epoxy acrylate, 11 parts of polycaprolactone, 1.1 parts of triethylamine, 1.9 parts of initiator, and 200 parts of solvent.

3. The carbon fiber prepreg with high low-temperature stability according to claim 1 or 2, characterized in that The number average molecular weight of the polycaprolactone is 2000-4000; the initiator is a UV initiator; and the solvent is one of tetrahydrofuran and acetone.

4. The carbon fiber prepreg with high low-temperature stability according to claim 1, characterized in that The resin matrix is prepared as follows: S1, pre-mixing, adding epoxy acrylate and polycaprolactone into a reaction kettle, then adding solvent, stirring until completely dissolved to obtain a solution for standby use; S2, adding triethylamine to the solution, stirring and reacting for 1.5-2.5 hours to obtain reaction solution A; S3, adding an initiator to the reaction solution A, stirring at room temperature for 25-35 minutes, and then performing vacuum degassing to obtain a reaction solution B; S4, concentrating the reaction solution B by reducing pressure until the solution viscosity reaches 900-1200 mPa·s at 25° C., thereby obtaining a resin matrix.

5. The carbon fiber prepreg with high low-temperature stability according to claim 4, characterized in that In step S1, the stirring process is carried out at 55-65°C; the stirring speed is 50-60 rpm, and the stirring time is 30-40 min.

6. The carbon fiber prepreg with high low-temperature stability according to claim 4, characterized in that In step S2, the stirring process is carried out at 60-65° C. and at a stirring speed of 30-40 rpm.

7. The carbon fiber prepreg with high low-temperature stability according to claim 4, characterized in that In step S4, concentration under reduced pressure is performed at 45-50°C.

8. The carbon fiber prepreg with high low-temperature stability according to claim 1, characterized in that In step 2, compressed air is used to clean the surface of the carbon fiber cloth before it enters the impregnation tank.

9. The carbon fiber prepreg with high low-temperature stability according to claim 1, wherein In step 5, the UV curing light source is a 365nm UV lamp with an irradiation intensity of 30-40Mw / cm 2 The irradiation time is 5-7 minutes and the irradiation distance is 10-15 cm.

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