Polyacrylonitrile-itaconic acid copolymer sizing agent as well as preparation method and application thereof

Abstract

The invention relates to the field of carbon fiber manufacturing, and discloses a polyacrylonitrile-itaconic acid copolymer sizing agent as well as a preparation method and application thereof. The sizing agent is prepared from 1 part by weight of acrylonitrile-itaconic acid copolymer, 1 to 20 parts by weight of bisphenol polyether epoxy resin and 0.05 to 5 parts by weight of phenolic resin; the weight-average molecular weight of the acrylonitrile-itaconic acid copolymer is 500 to 6000 g / mol. The sizing agent contains the acrylonitrile-itaconic acid copolymer and the bisphenol polyether epoxy with specific weight-average molecular weight, can have good compatibility with phenolic resin and epoxy resin, all the components have synergistic interaction, and when the sizing agent is applied to carbon fibers, the comprehensive performance of temperature resistance and interlaminar shear strength of the sized carbon fibers can be improved.

Description

Technical Field

[0001] The present invention relates to the field of carbon fiber manufacturing, and particularly relates to a polyacrylonitrile-itaconic acid copolymer sizing agent and its preparation method and application. Background Art

[0002] Carbon fiber has a series of excellent properties such as low density, high modulus, weavability, and high temperature resistance, and has become the most important reinforcing body in composite materials. Among them, high-strength and high-modulus carbon fiber, also known as graphite fiber, has a carbon content of more than 99%. Compared with traditional high-strength and medium-modulus carbon fiber, it has a higher modulus and is widely used in the aerospace field.

[0003] CN100999867A discloses a liquid polyacrylonitrile oligomer sizing agent and its application to carbon fiber. It prepares a liquid polyacrylonitrile oligomer by a free radical polymerization method, and obtains a polyacrylonitrile with a high carbon content and a cyclic structure through thermal oxidation treatment, and further formulates it into a sizing agent. By subjecting the liquid polyacrylonitrile with a low degree of polymerization to thermal oxidation treatment, it is provided with amino, cyano, and hydroxyl groups, and has a good effect when used in combination with an epoxy resin-based sizing agent. However, this oligomer lacks hydrophilic groups and has poor affinity with epoxy resin. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art that the bonding force between the sizing agent and carbon fiber is not strong, and the performance of the sized carbon fiber is not good. The present invention provides a polyacrylonitrile-itaconic acid copolymer sizing agent and its preparation method and application. The sizing agent contains an acrylonitrile-itaconic acid copolymer with a specific weight average molecular weight and a bisphenol polyether epoxy, and can have good compatibility with phenolic resin and epoxy resin. The components synergistically enhance each other. When applied as a sizing agent to carbon fiber, it can improve the comprehensive performance of the sized carbon fiber.

[0005] To achieve the above purpose, the first aspect of the present invention provides a polyacrylonitrile-itaconic acid copolymer sizing agent, wherein the sizing agent comprises: 1 part by weight of an acrylonitrile-itaconic acid copolymer, 1 - 20 parts by weight of a bisphenol polyether epoxy resin, and 0.05 - 5 parts by weight of a phenolic resin;

[0006] The weight average molecular weight of the acrylonitrile-itaconic acid copolymer is 500 - 6000 g / mol.

[0007] The second aspect of the present invention provides a preparation method of the sizing agent, wherein each component in the polyacrylonitrile-itaconic acid copolymer sizing agent described in the first aspect of the present invention is mixed to obtain a mixture, and emulsification is carried out to obtain the polyacrylonitrile-itaconic acid copolymer sizing agent.

[0008] The third aspect of the present invention provides a polyacrylonitrile-itaconic acid copolymer sizing agent prepared by the preparation method described in the second aspect.

[0009] The fourth aspect of the present invention provides an application of the polyacrylonitrile-itaconic acid copolymer sizing agent described in the first aspect or the third aspect of the present invention in the field of carbon fiber sizing.

[0010] Through the above technical solutions, the polyacrylonitrile-itaconic acid copolymer sizing agent provided by the present invention and its preparation method and application obtain the following beneficial effects: By introducing the acrylonitrile-itaconic acid copolymer into the sizing agent, on the one hand, its hydrophilicity can be improved, and it has good affinity with carbon fiber, thereby improving the mechanical properties of the obtained carbon fiber composite material. On the other hand, the acrylonitrile-itaconic acid copolymer has good high-temperature resistance, can form a ring on the surface of the carbon fiber and form a high-temperature resistant resin layer, so that the obtained carbon fiber composite material has excellent high-temperature resistance. Specific Embodiments

[0011] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0012] The first aspect of the present invention provides a sizing agent, wherein the sizing agent comprises: 1 part by weight of acrylonitrile-itaconic acid copolymer, 0.5 - 20 parts by weight of bisphenol polyether epoxy resin, and 0.05 - 5 parts by weight of phenolic resin;

[0013] The weight-average molecular weight of the acrylonitrile-itaconic acid copolymer is 500 - 6000 g / mol.

[0014] In the present invention, the sizing agent contains a specific ratio of acrylonitrile-itaconic acid copolymer, bisphenol polyether epoxy resin and phenolic resin, which can cooperate with each other. At the same time, in combination with the acrylonitrile-itaconic acid copolymer with a specific weight-average molecular weight, the acrylonitrile-itaconic acid copolymer sizing agent has good temperature resistance and hydrophilicity, can improve the bonding force with carbon fiber, and at the same time makes the sized carbon fiber have excellent temperature resistance and mechanical properties.

[0015] According to the present invention, the sizing agent further comprises 0.2 - 20 parts by weight of solvent A.

[0016] According to some embodiments of the present invention, the solvent A is selected from at least one of methanol, ethanol and acetone.

[0017] According to some preferred embodiments of the present invention, the sizing agent comprises: 1 part by weight of acrylonitrile-itaconic acid copolymer, 2-10 parts by weight of bisphenol polyether epoxy resin, 0.2-2 parts by weight of phenolic resin, and 0.5-5 parts by weight of solvent A.

[0018] According to some embodiments of the present invention, the acrylonitrile-itaconic acid copolymer has a weight average molecular weight of 1000-3000 g / mol.

[0019] According to some embodiments of the present invention, the acrylonitrile-itaconic acid copolymer has a molecular weight distribution index of 1-1.4, preferably 1.1-1.2.

[0020] According to the present invention, the acrylonitrile-itaconic acid copolymer has the structure shown in Formula I:

[0021]

[0022] Wherein, m is 1-50 and n is 1-50.

[0023] According to some embodiments of the present invention, R 1 and R 2 are each independently selected from Na, K, NH 4 or NH(CH 3 ) 3 .

[0024] In the present invention, in the acrylonitrile-itaconic acid copolymer, some carboxyl groups are hydrolyzed and converted into salts, which can improve the hydrophilicity of the copolymer and enhance the binding force between the sizing agent containing the copolymer and carbon fiber.

[0025] According to some embodiments of the present invention, in the acrylonitrile-itaconic acid copolymer, the content of the structural units provided by itaconic acid can be 5 mol%-60 mol%. Among them, the content of the structural units can be measured by nuclear magnetic method.

[0026] According to the present invention, the bisphenol polyether epoxy resin has the structure shown in Formula II:

[0027]

[0028] Wherein, x is 1-2;

[0029] R 3 is selected from

[0030] R 4 is selected from

[0031] o is 4-50, p is 3-40, and q is 3-30.

[0032] According to the present invention, the weight-average molecular weight of the bisphenol polyether epoxy resin is 800-5000 g / mol, preferably 1000-3000 g / mol.

[0033] According to the present invention, the average particle size of the polyacrylonitrile-itaconic acid copolymer sizing agent is 200-500 nm.

[0034] In the present invention, the average particle size of the polyacrylonitrile-itaconic acid copolymer sizing agent is measured by the method of GB / T 19077-2016 for the average particle size of the copolymer and resin particles in the sizing agent.

[0035] In the present invention, when the average particle size of the polyacrylonitrile-itaconic acid copolymer sizing agent meets the above range, the sizing amount of the sized carbon fiber can be made more uniform, thereby obtaining better comprehensive properties.

[0036] Further, the average particle size of the polyacrylonitrile-itaconic acid copolymer sizing agent is 300-500 nm.

[0037] According to the present invention, the saturated water absorption rate of the polyacrylonitrile-itaconic acid copolymer sizing agent is ≤0.2%.

[0038] In the present invention, when the saturated water absorption rate of the polyacrylonitrile-itaconic acid copolymer sizing agent meets the above range, the sized carbon fiber prepared has better anti-aging performance.

[0039] In the second aspect of the present invention, a method for preparing a sizing agent is provided. Among them, each component in the polyacrylonitrile-itaconic acid copolymer sizing agent described in the first aspect of the present invention is mixed to obtain a mixture, and the mixture is emulsified to obtain the polyacrylonitrile-itaconic acid copolymer sizing agent.

[0040] In the present invention, the types and amounts of each component in the polyacrylonitrile-itaconic acid copolymer sizing agent are the same as those in the first aspect of the present invention, and will not be elaborated here.

[0041] According to the present invention, the conditions for emulsification include: the rotation speed is 3000-11000 r / min, and the time is 0.2-2 h.

[0042] In the present invention, the emulsification is carried out at 0-40 °C.

[0043] According to a preferred embodiment of the present invention, the method further includes: before emulsifying the mixture, adjusting the solid content of the mixture to 10 wt%-50 wt%.

[0044] In the present invention, adjusting the mixture to a solid content of 10 wt%-50 wt% can save storage space and is easy to transport.

[0045] According to an embodiment of the present invention, the acrylonitrile-itaconic acid copolymer is prepared according to the following method:

[0046] S1. Mix acrylonitrile monomer, itaconic acid monomer, initiator, solvent B and chain transfer agent, carry out the first reaction I, and then remove solvent B and chain transfer agent to obtain a mixture;

[0047] S2. Mix the mixture, water and neutralizing agent, and carry out the second reaction I to obtain the acrylonitrile-itaconic acid copolymer.

[0048] According to some embodiments of the present invention, the mass ratio of the acrylonitrile monomer: the itaconic acid monomer: the initiator I: the chain transfer agent: the solvent B is 1: 0.1-25: 0.005-0.2: 0.005-0.2: 2-250.

[0049] In the present invention, when the mass ratio of the acrylonitrile monomer: the itaconic acid monomer: the initiator I: the chain transfer agent: the solvent B satisfies the above range, the molecular weight distribution of the prepared polymer can be more uniform.

[0050] Further, the mass ratio of the acrylonitrile monomer: the itaconic acid monomer: the initiator I: the chain transfer agent: the solvent B is 1: 0.2-2: 0.01-0.1: 0.01-0.1: 5-50.

[0051] According to an embodiment of the present invention, the solvent B is selected from dimethyl sulfoxide.

[0052] According to some embodiments of the present invention, the mass ratio of the acrylonitrile monomer: the water: the neutralizing agent is 1: 1-50: 0.05-20, preferably 1: 2-20: 0.1-10.

[0053] According to some embodiments of the present invention, the reaction temperature is 60-90 °C and the reaction time is 2-8 h.

[0054] According to some embodiments of the present invention, the conditions of the second reaction I include: the reaction temperature is 50-70 °C and the reaction time is 1-3 h.

[0055] According to an embodiment of the present invention, the bisphenol polyether epoxy resin is prepared according to the following method:

[0056] a. Carry out the first reaction II on bisphenol epoxy resin, polyether and initiator II to obtain bisphenol polyether;

[0057] b. Mix the bisphenol polyether, epichlorohydrin, base and catalyst, and carry out the second reaction II to obtain bisphenol polyether epoxy resin.

[0058] According to some embodiments of the present invention, in step a, the mass ratio of the bisphenol epoxy resin: the polyether: the initiator II is 1:0.5 - 20:0.005 - 0.2, preferably 1:1 - 10:0.01 - 0.1.

[0059] In the present invention, step a is preferably carried out in the presence of acetone and water. Through the research of the inventors, it is found that when the mass ratio of the bisphenol epoxy resin: acetone: water is 1:0.05 - 20:0.05 - 20, better effects can be obtained. More preferably, the mass ratio of the bisphenol epoxy resin: acetone: water is 1:1 - 10:1 - 10.

[0060] In the present invention, after the first reaction II in step a, preferably after vacuum distillation, acetone is re-added for recrystallization, and the mass ratio of the bisphenol epoxy resin: acetone is 1:0.05 - 20, preferably 1:1 - 10.

[0061] According to some embodiments of the present invention, in step b, the mass ratio of the bisphenol polyether: the epichlorohydrin: the base: the catalyst is 1:0.05 - 2:0.005 - 0.2:0.005 - 0.2, preferably 1:0.1 - 1:0.01 - 0.1:0.01 - 0.1.

[0062] In the present invention, after the second reaction II in step b, preferably after vacuum distillation, acetone is re-added for recrystallization, and the mass ratio of the bisphenol polyether: acetone is 1:0.1 - 5, preferably 1:0.2 - 2.

[0063] According to some embodiments of the present invention, the conditions of the first reaction II include: the reaction temperature is 30 - 60 °C, and the reaction time is 4 - 12 h.

[0064] According to some embodiments of the present invention, the conditions of the second reaction II include: the reaction temperature is 90 - 120 °C, and the reaction time is 1 - 3 h.

[0065] According to some embodiments of the present invention, the chain transfer agent is selected from at least one of isopropanol, 2-butanol, 2-pentanol, 2-hexanol, and 2-heptanol.

[0066] According to some embodiments of the present invention, the neutralizing agent is selected from at least one of sodium hydroxide, potassium hydroxide, ammonia water, and triethylamine.

[0067] According to some embodiments of the present invention, the polyether is selected from at least one of polyethylene glycol-200, polyethylene glycol-400, polyethylene glycol-600, polyethylene glycol-800, polyethylene glycol-1000, polyethylene glycol-1500, polyethylene glycol-2000, polypropylene glycol-200, polypropylene glycol-400, polypropylene glycol-600, polypropylene glycol-800, polypropylene glycol-1000, polypropylene glycol-1500, and polypropylene glycol-2000.

[0068] According to some embodiments of the present invention, the bisphenol epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, and bisphenol S epoxy resin.

[0069] In the present invention, the bisphenol A epoxy resin may be E-55, E-54, E-51, or E-44, the bisphenol F epoxy resin may be CYDF-170 or CYDF-175, and the bisphenol S epoxy resin may be 185S.

[0070] According to some embodiments of the present invention, the base is sodium hydroxide and / or potassium hydroxide.

[0071] According to some embodiments of the present invention, the catalyst is tetra-n-butylammonium bromide and / or tetra-n-butylammonium chloride.

[0072] The third aspect of the present invention provides an acrylonitrile-itaconic acid copolymer sizing agent prepared by the preparation method described in the second aspect.

[0073] The fourth aspect of the present invention provides an application of the acrylonitrile-itaconic acid copolymer sizing agent described in the first aspect or the third aspect of the present invention in the field of carbon fiber sizing.

[0074] The present invention will be described in detail below through examples.

[0075] In the following examples, the average particle size of the acrylonitrile-itaconic acid copolymer sizing agent was measured by GB / T19077-2016;

[0076] The temperature resistance of the acrylonitrile-itaconic acid copolymer sizing agent was measured by a thermogravimetric analyzer, and the temperature at which the sizing agent was completely burned out in an air atmosphere was recorded;

[0077] The stability of the acrylonitrile-itaconic acid copolymer sizing agent was tested by the following method: Starting from the time when the sizing agent prepared in the example was left standing after preparation, until the time when it began to settle, the longer the time, the better the stability.

[0078] The saturated water absorption rate of the acrylonitrile-itaconic acid copolymer sizing agent was measured by the method of FZ / T 50031-2015;

[0079] The interlaminar shear strength (ILSS) of the composite material was measured by the method of JC / T 773-2010, and the resin used in the ILSS test was epoxy resin;

[0080] All raw materials are commercially available products.

[0081] Example 1

[0082] S1. At 65 °C, 1.59 g of acrylonitrile, 2.6 g of itaconic acid, 0.04 g of azobisisobutyronitrile, 0.05 g of 2-heptanol and 38.07 g of dimethyl sulfoxide were added to a reactor and mixed evenly to obtain a mixture. After reacting the above mixture at 65 °C for 3 h, it was cooled to 25 °C, and dimethyl sulfoxide and 2-heptanol were removed by vacuum distillation. 20 g of water and 4.05 g of triethylamine were added, and the reaction was carried out at 60 °C for 2 h with stirring, and then water was removed by vacuum distillation to obtain an acrylonitrile-itaconic acid copolymer (PAN / IA resin), named A1;

[0083] S2. At 50 °C, 6.8 g of bisphenol A epoxy resin (E-55), 24 g of polyethylene glycol (PEG-600), 0.25 g of potassium persulfate, 20 g of acetone and 20 g of water were added to a reactor, stirred for 8 hours, cooled to 25 °C, and acetone and water were removed by vacuum distillation. 30 g of acetone was added for recrystallization, stirred, filtered, and acetone in the filtrate was removed by vacuum distillation to obtain bisphenol polyether;

[0084] S3. At 100 °C, 30.8 g of the above bisphenol polyether, 11.1 g of epichlorohydrin, 1.6 g of sodium hydroxide, and 1.29 g of tetrabutylammonium bromide were added to a reactor, stirred for 2 hours, cooled to 25 °C, and water was removed by vacuum distillation. 30 g of acetone was added for recrystallization, stirred, filtered, and acetone in the filtrate was removed by vacuum distillation to obtain bisphenol polyether epoxy resin, named B1;

[0085] S4. At 25 °C, 8.28 g of the PAN / IA resin A1 obtained in step S1, 32.52 g of the bisphenol polyether epoxy resin B1 obtained in step S3, and 3.72 g of phenolic resin were added to a reactor, 10 g of acetone was added, and water was added to dilute the mixed system to a solid content of 20 wt%, and emulsified at 10000 rpm for 1 hour to prepare the PAN / IA sizing agent S1.

[0086] Among them, the weight-average molecular weight, molecular weight distribution index of the acrylonitrile-itaconic acid copolymer A-1, and the weight-average molecular weight of the bisphenol polyether epoxy resin B1 are shown in Table 1 in detail, and the average particle size, saturated water absorption rate, stability and heat resistance of the PAN / IA sizing agent S1 are shown in Table 2 in detail.

[0087] Example 2

[0088] S1. At 65 °C, 2.12 g of acrylonitrile, 1.3 g of itaconic acid, 0.04 g of azobisisobutyronitrile, 0.05 g of 2-heptanol and 31.14 g of dimethyl sulfoxide were added to a reactor and mixed evenly to obtain a mixture. After reacting the above mixture at 65 °C for 3 h, the temperature was lowered to 25 °C, and dimethyl sulfoxide and 2-heptanol were removed by vacuum distillation. 20 g of water and 2.03 g of triethylamine were added, and the mixture was stirred and reacted at 60 °C for 2 h. Water was removed by vacuum distillation to obtain PAN / IA resin, named A-2;

[0089] S2. At 50 °C, 6.8 g of bisphenol A epoxy resin (E-55), 24 g of polyethylene glycol (PEG-600), 0.25 g of potassium persulfate, 20 g of acetone and 20 g of water were added to a reactor and stirred for 8 h. The temperature was lowered to 25 °C, and acetone and water were removed by vacuum distillation. 30 g of acetone was added for recrystallization, stirred, filtered, and acetone in the filtrate was removed by vacuum distillation to obtain bisphenol polyether;

[0090] S3. At 100 °C, 30.8 g of the above bisphenol polyether, 11.1 g of epichlorohydrin, 1.6 g of sodium hydroxide, and 1.29 g of tetrabutylammonium bromide were added to a reactor and stirred for 2 h. The temperature was lowered to 25 °C, and water was removed by vacuum distillation. 30 g of acetone was added for recrystallization, stirred, filtered, and acetone in the filtrate was removed by vacuum distillation to obtain bisphenol polyether epoxy resin B2;

[0091] S4. At 25 °C, 5.49 g of PAN / IA resin A2, 32.52 g of bisphenol polyether epoxy resin B2 and 4.34 g of phenolic resin were added to a reactor, 10 g of acetone was added, and water was added to dilute the mixed system to a solid content of 20 wt%. The mixture was emulsified at 10000 rpm for 1 h to prepare PAN / IA sizing agent S2;

[0092] Among them, the weight-average molecular weight, molecular weight distribution index of acrylonitrile-itaconic acid copolymer A2, and the weight-average molecular weight of bisphenol polyether epoxy resin B2 are shown in Table 1, and the average particle size, saturated water absorption, stability and temperature resistance of PAN / IA sizing agent S2 are shown in Table 2.

[0093] Example 3

[0094] S1. At 65 °C, 1.59 g of acrylonitrile, 2.6 g of itaconic acid, 0.04 g of azobisisobutyronitrile, 0.05 g of 2-heptanol and 38.07 g of dimethyl sulfoxide were added to a reactor. After reacting for 3 h, the temperature was lowered to 25 °C, and dimethyl sulfoxide and 2-heptanol were removed by vacuum distillation. 11.2 g of ammonia water (concentration 25 wt%) and 20 g of water were added, stirred, and reacted at 60 °C for 2 h. Water was removed by vacuum distillation to obtain PAN / IA resin A3;

[0095] S2. At 50 °C, add 6.8 g of bisphenol A epoxy resin (E-55), 24 g of polyethylene glycol (PEG-600), 0.25 g of potassium persulfate, 20 g of acetone and 20 g of water to the reactor, stir for 8 hours, cool to 25 °C, remove acetone and water by vacuum distillation, add 30 g of acetone for recrystallization, stir, filter, and remove acetone in the filtrate by vacuum distillation to obtain bisphenol polyether;

[0096] S3. At 100 °C, add 30.8 g of bisphenol polyether, 11.1 g of epichlorohydrin, 1.6 g of sodium hydroxide, and 1.29 g of tetrabutylammonium bromide to the reactor, stir for 2 hours, cool to 25 °C, remove water by vacuum distillation, add 30 g of acetone for recrystallization, stir, filter, and remove acetone in the filtrate by vacuum distillation to obtain bisphenol polyether epoxy B3;

[0097] S4. At 25 °C, add 4.91 g of PAN / IA resin A3, 32.52 g of bisphenol polyether epoxy resin B3 and 3.72 g of phenolic resin to the reactor, add 10 g of acetone, and dilute the mixed system with water to a solid content of 20 wt%, emulsify at 10000 rpm for 1 hour to prepare PAN / IA sizing agent S3.

[0098] Among them, the weight-average molecular weight, molecular weight distribution index of acrylonitrile-itaconic acid copolymer A3, and the weight-average molecular weight of bisphenol polyether epoxy resin B3 are shown in Table 1, and the average particle size, saturated water absorption, stability and heat resistance of PAN / IA sizing agent S3 are shown in Table 2.

[0099] Example 4

[0100] S1. At 65 °C, add 1.59 g of acrylonitrile, 2.6 g of itaconic acid, 0.04 g of azobisisobutyronitrile, 0.05 g of 2-heptanol and 38.07 g of dimethyl sulfoxide to the reactor. After reacting for 3 hours, cool to 25 °C, remove dimethyl sulfoxide and 2-heptanol by vacuum distillation, add 4.05 g of triethylamine and 20 g of water, stir, react at 60 °C for 2 hours, and remove water by vacuum distillation to obtain PAN / IA resin A4;

[0101] S2. At 50 °C, add 9.8 g of bisphenol A epoxy resin (E-44), 40 g of polyethylene glycol (PEG-1000), 0.25 g of potassium persulfate, 30 g of acetone and 30 g of water to the reactor, stir for 8 hours, cool to 25 °C, remove acetone and water by vacuum distillation, add 50 g of acetone for recrystallization, stir, filter, and remove acetone in the filtrate by vacuum distillation to obtain bisphenol polyether;

[0102] S3. At 100 °C, add 30.8 g of the above-mentioned bisphenol polyether, 11.1 g of epichlorohydrin, 1.6 g of sodium hydroxide, and 1.29 g of tetrabutylammonium bromide to a reactor, stir for 2 hours, cool to 25 °C, remove water by vacuum distillation, add 30 g of acetone for recrystallization, stir, filter, and remove acetone in the filtrate by vacuum distillation to obtain bisphenol polyether epoxy resin B4;

[0103] S4. At 25 °C, add 8.28 g of PAN / IA resin A4, 51.52 g of bisphenol polyether epoxy resin B4, and 3.72 g of phenolic resin to a reactor, add 10 g of acetone, and dilute the mixed system with water to a solid content of 20 wt%, emulsify at 10000 rpm for 1 hour to obtain PAN / IA sizing agent S4.

[0104] Among them, the weight-average molecular weight, molecular weight distribution index of acrylonitrile-itaconic acid copolymer A4, and the weight-average molecular weight of bisphenol polyether epoxy resin B4 are shown in Table 1, and the average particle size, saturated water absorption, stability, and temperature resistance of PAN / IA sizing agent S4 are shown in Table 2.

[0105] Example 5

[0106] S1. At 65 °C, add 1.59 g of acrylonitrile, 2.6 g of itaconic acid, 0.04 g of azobisisobutyronitrile, 0.05 g of 2-heptanol, and 38.07 g of dimethyl sulfoxide to a reactor. After reacting for 3 hours, cool to 25 °C, remove dimethyl sulfoxide and 2-heptanol by vacuum distillation, add 4.05 g of triethylamine and 20 g of water, stir, react at 60 °C for 2 hours, and remove water by vacuum distillation to obtain PAN / IA resin A5;

[0107] S2. At 50 °C, add 6.8 g of bisphenol A epoxy resin (E-55), 24 g of polyethylene glycol (PEG-600), 0.25 g of potassium persulfate, 20 g of acetone, and 20 g of water to a reactor, stir for 8 hours, cool to 25 °C, remove acetone and water by vacuum distillation, add 30 g of acetone for recrystallization, stir, filter, and remove acetone in the filtrate by vacuum distillation to obtain bisphenol polyether;

[0108] S3. At 100 °C, add 30.8 g of the above-mentioned bisphenol polyether, 11.1 g of epichlorohydrin, 1.6 g of sodium hydroxide, and 1.29 g of tetrabutylammonium bromide to a reactor, stir for 2 hours, cool to 25 °C, remove water by vacuum distillation, add 30 g of acetone for recrystallization, stir, filter, and remove acetone in the filtrate by vacuum distillation to obtain bisphenol polyether epoxy resin B5;

[0109] S4. At 25 °C, 4.14 g of PAN / IA resin A5, 32.52 g of bisphenol polyether epoxy resin B5 and 4.34 g of phenolic resin were added to a reactor. 10 g of acetone was added, and water was added to dilute the mixed system to a solid content of 20 wt%. It was emulsified at 10000 rpm for 1 hour to obtain the PAN / IA sizing agent S5.

[0110] Among them, the weight-average molecular weight, molecular weight distribution index of the acrylonitrile-itaconic acid copolymer A5, and the weight-average molecular weight of the bisphenol polyether epoxy resin B5 are shown in Table 1 in detail. The average particle size, saturated water absorption rate, stability and temperature resistance of the PAN / IA sizing agent S5 are shown in Table 2 in detail.

[0111] Example 6

[0112] S1. The same as in Example 1;

[0113] S2. At 50 °C, 6.24 g of bisphenol F epoxy resin (CYDF-170), 24 g of polyethylene glycol (PEG-600), 0.25 g of potassium persulfate, 20 g of acetone and 20 g of water were added to a reactor, stirred for 8 hours, cooled to 25 °C, and acetone and water were removed by vacuum distillation. 30 g of acetone was added for recrystallization, stirred, filtered, and acetone in the filtrate was removed by vacuum distillation to obtain bisphenol polyether;

[0114] S3. At 100 °C, 30.24 g of the above-mentioned bisphenol polyether, 11.1 g of epichlorohydrin, 1.6 g of sodium hydroxide, and 1.29 g of tetrabutylammonium bromide were added to a reactor, stirred for 2 hours, cooled to 25 °C, water was removed by vacuum distillation, 30 g of acetone was added for recrystallization, stirred, filtered, and acetone in the filtrate was removed by vacuum distillation to obtain bisphenol polyether epoxy resin B6;

[0115] S4. At 25 °C, 8.28 g of the PAN / IA resin obtained in step S1, 31.96 g of the bisphenol polyether epoxy resin obtained in step S3 and 3.72 g of phenolic resin were added to a reactor. 10 g of acetone was added, and water was added to dilute the mixed system to a solid content of 20 wt%. It was emulsified at 10000 rpm for 1 hour to obtain the PAN / IA sizing agent S6.

[0116] Among them, the weight-average molecular weight, molecular weight distribution index of the acrylonitrile-itaconic acid copolymer, and the weight-average molecular weight of the bisphenol polyether epoxy resin B6 are shown in Table 1 in detail. The average particle size, saturated water absorption rate, stability and temperature resistance of the PAN / IA sizing agent S6 are shown in Table 2 in detail.

[0117] Comparative Example 1

[0118] S1. Prepare bisphenol polyether epoxy resin B1 according to the method of Example 1;

[0119] S2. At 25 °C, 32.52 g of bisphenol A polyether epoxy and 4.97 g of phenolic resin were added to a reactor, 10 g of acetone was added, and water was added to dilute the mixed system to a solid content of 20 wt%, and emulsified at 10,000 rpm for 1 hour to obtain the PAN / IA sizing agent DS1.

[0120] Among them, the weight-average molecular weight of the bisphenol-based polyether epoxy resin is shown in Table 1, and the average particle size, saturated water absorption rate, stability and temperature resistance of the PAN / IA sizing agent DS1 are shown in Table 2.

[0121] Comparative Example 2

[0122] S1. At 65 °C, 2.55 g of acrylonitrile, 0.26 g of itaconic acid, 0.04 g of azobisisobutyronitrile, 0.05 g of 2-heptanol and 25.65 g of dimethyl sulfoxide were added to a reactor. After reacting for 3 hours, the temperature was lowered to 25 °C, and dimethyl sulfoxide and 2-heptanol were removed by vacuum distillation. 0.2 g of sodium hydroxide and 20 g of water were added, stirred, and reacted at 60 °C for 2 hours. Water was removed by vacuum distillation to obtain the PAN / IA resin DA2;

[0123] S2. At 50 °C, 6.8 g of bisphenol A epoxy resin (E-55), 24 g of polyethylene glycol (PEG-600), 0.25 g of potassium persulfate, 20 g of acetone and 20 g of water were added to a reactor, stirred for 8 hours, the temperature was lowered to 25 °C, and acetone and water were removed by vacuum distillation. 30 g of acetone was added, stirred, filtered, and acetone in the filtrate was removed by vacuum distillation to obtain bisphenol-based polyether;

[0124] S3. At 100 °C, 30.8 g of the above-mentioned bisphenol-based polyether, 11.1 g of epichlorohydrin, 1.6 g of sodium hydroxide, and 1.29 g of tetrabutylammonium bromide were added to a reactor, stirred for 2 hours, the temperature was lowered to 25 °C, and acetone and water were removed by vacuum distillation. 30 g of acetone was added, stirred, filtered, and acetone in the filtrate was removed by vacuum distillation to obtain bisphenol-based polyether epoxy resin;

[0125] S4. At 25 °C, 3.05 g of the PAN / IA resin obtained in step S1, 32.52 g of the bisphenol A polyether epoxy obtained in step S3 and 4.85 g of phenolic resin were added to a reactor, 10 g of acetone was added, and water was added to dilute the mixed system to a solid content of 20 wt%, and emulsified at 10,000 rpm for 1 hour to obtain the PAN / IA sizing agent DS2.

[0126] Among them, the weight-average molecular weight, molecular weight distribution index of the acrylonitrile-itaconic acid copolymer, and the weight-average molecular weight of the bisphenol-based polyether epoxy resin are shown in Table 1, and the average particle size, saturated water absorption rate, stability and temperature resistance of the PAN / IA sizing agent DS2 are shown in Table 2.

[0127] Comparative Example 3

[0128] S1. The same as in Example 1.

[0129] S2. At 50 °C, add 3.4 g of bisphenol A epoxy resin (E-55), 12 g of polyethylene glycol (PEG-600), 0.125 g of potassium persulfate, 10 g of acetone and 10 g of water into the reactor, stir for 8 hours, cool to 25 °C, remove acetone and water by vacuum distillation, add 15 g of acetone, stir, filter, and remove acetone in the filtrate by vacuum distillation to obtain bisphenol polyether.

[0130] S3. At 100 °C, add 7.7 g of the above-mentioned bisphenol polyether, 2.78 g of epichlorohydrin, 0.4 g of sodium hydroxide, and 0.32 g of tetrabutylammonium bromide into the reactor, stir for 2 hours, cool to 25 °C, remove acetone and water by vacuum distillation, add 7.5 g of acetone, stir, filter, and remove acetone in the filtrate by vacuum distillation to obtain bisphenol polyether epoxy resin DB3.

[0131] S4. At 25 °C, add 8.28 g of the PAN / IA resin obtained in step S1, 8.13 g of the bisphenol polyether epoxy resin DB3 obtained in step S3 and 0.31 g of phenolic resin into the reactor, add 10 g of acetone, and dilute the mixed system with water to a solid content of 20 wt%, emulsify at 10000 rpm for 1 hour to prepare the PAN / IA sizing agent DS3.

[0132] Among them, the weight-average molecular weight, molecular weight distribution index of the acrylonitrile-itaconic acid copolymer, and the weight-average molecular weight of the bisphenol polyether epoxy resin are shown in Table 1 in detail, and the average particle size, saturated water absorption rate, stability and temperature resistance of the PAN / IA sizing agent DS3 are shown in Table 2 in detail.

[0133] Comparative Example 4

[0134] According to the method of Example 1, the difference is that the bisphenol polyether epoxy resin B1 is not contained, and the emulsion cannot be formed, so the sizing agent cannot be prepared.

[0135] Table 1

[0136]

[0137]

[0138] Note: A refers to the acrylonitrile-itaconic acid copolymer, and B refers to the bisphenol polyether epoxy resin.

[0139] Table 2

[0140] Number Average particle size / nm Saturated water absorption rate / % Temperature resistance / °C Stability / months S1 476 0.1 712 6 S2 492 0.08 723 6 S3 498 0.1 713 6 S4 489 0.08 711 6 S5 496 0.09 708 6 S6 452 0.1 732 6 DS1 682 0.07 615 6 DS2 573 0.15 735 6 DS3 423 0.25 718 1

[0141] Test Example

[0142] The sizing agents prepared in the examples and comparative examples were diluted to 2 wt%, used for sizing carbon fibers, dried at 110 - 160 °C, wound, and the sizing rate was 1 - 1.3 wt%, to obtain sized carbon fibers 1 - 10, and their properties were tested, and the results are shown in Table 3.

[0143] Sized carbon fiber Sizing agent type Sizing amount / wt% Interlaminar shear strength / MPa 1 S1 1.2 88 2 S2 1 81 3 S3 1.2 88 4 S4 1.3 72 5 S5 1.1 83 6 S6 1.1 88 7 DS1 0.8 78 8 DS2 1.3 52 9 DS3 1.1 54

[0144] From the above results, it can be seen that Examples 1 - 6 of the present invention have good technical effects. The prepared sizing agent has a suitable particle size, the saturated water absorption rate is lower than 0.2%, and it has excellent heat resistance and stability, and can be stored stably for more than 6 months.

[0145] In Comparative Example 1, since it does not contain acrylonitrile-itaconic acid copolymer, the average particle size of the prepared sizing agent is too large, the coating is uneven when sizing carbon fibers, and at the same time, the heat resistance is poor, not exceeding 700 °C.

[0146] In Comparative Example 2, since the weight average molecular weight of the acrylonitrile-itaconic acid copolymer does not meet the requirements, the average particle size of the sizing agent is too large, the coating is uneven when sizing carbon fibers, and at the same time, the interlaminar shear strength of the prepared sized carbon fiber is reduced.

[0147] In Comparative Example 3, since the dosage ratio of the acrylonitrile-itaconic acid copolymer and bisphenol polyether epoxy resin does not meet the requirements, the interlaminar shear strength of the prepared sized carbon fiber is reduced.

[0148] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A polyacrylonitrile-itaconic acid copolymer sizing agent, characterized in that, the sizing agent comprises: 1 part by weight of acrylonitrile-itaconic acid copolymer, 1-20 parts by weight of bisphenol polyether epoxy resin, and 0.05-5 parts by weight of phenolic resin; the weight-average molecular weight of the acrylonitrile-itaconic acid copolymer is 500-6000 g / mol.

2. The polyacrylonitrile-itaconic acid copolymer sizing agent according to claim 1, wherein, the sizing agent further comprises 0.2-20 parts by weight of solvent A; and / or, the solvent A is selected from at least one of methanol, ethanol and acetone; preferably, the sizing agent comprises: 1 part by weight of acrylonitrile-itaconic acid copolymer, 2-10 parts by weight of bisphenol polyether epoxy resin, 0.2-2 parts by weight of phenolic resin, and 0.5-5 parts by weight of solvent A; and / or, the weight-average molecular weight of the acrylonitrile-itaconic acid copolymer is 1000-3000 g / mol; and / or, the molecular weight distribution index of the acrylonitrile-itaconic acid copolymer is 1-1.4, preferably 1.1-1.

2.

3. The polyacrylonitrile-itaconic acid copolymer sizing agent according to claim 1 or 2, wherein, the acrylonitrile-itaconic acid copolymer has the structure shown in Formula I: wherein, m is 1-50 and n is 1-50; and / or, R 1 and R 2 each independently selected from Na, K, NH 4 or NH(CH 3 ) 3 。 4. The polyacrylonitrile-itaconic acid copolymer sizing agent according to any one of claims 1-3, wherein, the bisphenol polyether epoxy resin has the structure shown in Formula II: wherein, x is 1-2; R 3 selected from R 4 selected from o is 4-50, p is 3-40, q is 3-30; and / or, the weight-average molecular weight of the bisphenol polyether epoxy resin is 800-5000 g / mol, preferably 1000-3000 g / mol.

5. The polyacrylonitrile-itaconic acid copolymer sizing agent according to any one of claims 1-4, wherein, the average particle size of the polyacrylonitrile-itaconic acid copolymer sizing agent is 200-500 nm, preferably 300-500 nm; and / or, the saturated water absorption rate of the polyacrylonitrile-itaconic acid copolymer sizing agent is ≤0.2%.

6. A preparation method of a polyacrylonitrile-itaconic acid copolymer sizing agent, characterized in that, each component in the polyacrylonitrile-itaconic acid copolymer sizing agent according to any one of claims 1-5 is mixed to obtain a mixture, and the mixture is emulsified to obtain the polyacrylonitrile-itaconic acid copolymer sizing agent.

7. The preparation method according to claim 6, wherein, the conditions of the emulsification include: the rotation speed is 3000-11000 r / min and the time is 0.2-2 h; and / or, the method further comprises: before emulsifying the mixture, adjusting the solid content of the mixture to 10 wt%-50 wt%.

8. The method according to claim 6 or 7, wherein, the acrylonitrile-itaconic acid copolymer is prepared according to the following method: S1. Acrylonitrile monomer, itaconic acid monomer, initiator, solvent B and chain transfer agent are mixed and then subjected to the first reaction I, and then solvent B and chain transfer agent are removed to obtain a mixture; S2. Mix the mixture, water and neutralizing agent, and then carry out the second reaction I to obtain an acrylonitrile-itaconic acid copolymer; Among them, the mass ratio of the acrylonitrile monomer: the itaconic acid monomer: the initiator I: the chain transfer agent: the solvent B is 1: 0.1-25: 0.005-0.2: 0.005-0.2: 2-250; and / or, the mass ratio of the acrylonitrile monomer: the water: the neutralizing agent is 1: 1-50: 0.05-20; and / or, the conditions of the first reaction I include: the reaction temperature is 60-90 °C, and the reaction time is 2-8 h; and / or, the conditions of the second reaction I include: the reaction temperature is 50-70 °C, and the reaction time is 1-3 h.

9. The preparation method according to any one of claims 6-8, wherein, The bisphenol polyether epoxy resin is prepared according to the following method: a. Carry out the first reaction II on the bisphenol epoxy resin, polyether and initiator II to obtain bisphenol polyether; b. Mix the bisphenol polyether, epichlorohydrin, alkali and catalyst, and then carry out the second reaction II to obtain bisphenol polyether epoxy resin; and / or, in step a, the mass ratio of the bisphenol epoxy resin: the polyether: the initiator II is 1: 0.5-20: 0.005-0.2; and / or, in step b, the mass ratio of the bisphenol polyether: the epichlorohydrin: the alkali: the catalyst is 1: 0.05-2: 0.005-0.2: 0.005-0.2; and / or, the conditions of the first reaction II include: the reaction temperature is 30-60 °C, and the reaction time is 4-12 h; and / or, the conditions of the second reaction II include: the reaction temperature is 90-120 °C, and the reaction time is 1-3 h.

10. The preparation method according to claim 8 or 9, wherein, The chain transfer agent is selected from at least one of isopropanol, 2-butanol, 2-pentanol, 2-hexanol and 2-heptanol; and / or, the neutralizing agent is selected from at least one of sodium hydroxide, potassium hydroxide, ammonia water and triethylamine.

11. The preparation method according to any one of claims 8-10, wherein, The polyether is selected from at least one of polyethylene glycol-200, polyethylene glycol-400, polyethylene glycol-600, polyethylene glycol-800, polyethylene glycol-1000, polyethylene glycol-1500, polyethylene glycol-2000, polypropylene glycol-200, polypropylene glycol-400, polypropylene glycol-600, polypropylene glycol-800, polypropylene glycol-1000, polypropylene glycol-1500 and polypropylene glycol-2000; and / or, the bisphenol epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin and bisphenol S epoxy resin; and / or, the alkali is sodium hydroxide and / or potassium hydroxide; and / or, the catalyst is tetrabutylammonium bromide and / or tetrabutylammonium chloride.

12. A sizing agent of polyacrylonitrile-itaconic acid copolymer prepared by the preparation method according to any one of claims 5-10.

13. Use of the polyacrylonitrile-itaconic acid copolymer sizing agent according to any one of claims 1-5 and 12 in the field of sizing carbon fibers.

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