A sizing agent and a preparation method thereof, carbon fibers and composite materials

Abstract

The application provides a sizing agent and a preparation method thereof, carbon fibers and composite materials, and belongs to the technical field of carbon fiber sizing agents. The sizing agent is in the form of emulsion, and the sizing agent comprises a main sizing agent and water. The main sizing agent comprises the following components in parts by weight: 20-50 parts of terminal epoxy polyether silicone oil, 25-55 parts of epoxy resin, 10-30 parts of an emulsifier and 5-25 parts of a smoothing agent. By adding the terminal epoxy polyether silicone oil into the sizing agent, the flexibility, heat resistance and water resistance of the carbon fibers treated by the sizing agent can be improved, and the interfacial bonding strength of the composite material formed by the carbon fibers and the matrix resin in a humid heat environment can be improved. Moreover, the carbon fibers treated by the sizing agent have good opening properties after the terminal epoxy polyether silicone oil is added into the sizing agent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon fiber sizing agent, in particular to a sizing agent, a preparation method thereof, carbon fiber and a composite material. BACKGROUND

[0002] The sizing agent plays an important role in the production and processing of carbon fiber. It can not only protect the fiber surface, but also introduce a proper interface layer between the carbon fiber and the matrix resin, so that the matrix resin and the fiber are well combined, and the interface performance of the composite material formed by the carbon fiber and the matrix resin is improved.

[0003] However, the existing sizing agent treated carbon fiber has low flexibility and poor heat resistance, and in a humid and hot environment, the interface bonding force of the composite material formed by the carbon fiber and the matrix resin will be weakened, which affects the mechanical properties of the composite material in the humid and hot environment. SUMMARY

[0004] The present application aims to provide a sizing agent, a preparation method thereof, carbon fiber and a composite material, which aims to improve the technical problems of low flexibility and poor heat resistance of the existing sizing agent treated carbon fiber, and the weakening of the interface bonding force of the composite material formed by the carbon fiber and the matrix resin in a humid and hot environment.

[0005] In a first aspect, the present application provides a sizing agent, the sizing agent being in the form of emulsion, and the sizing agent comprising a main sizing agent and water; the main sizing agent comprises the following components in parts by weight: 20-50 parts of terminal epoxy polyether silicone oil, 25-55 parts of epoxy resin, 10-30 parts of emulsifier and 5-25 parts of smoothing agent.

[0006] The present application adds terminal epoxy polyether silicone oil to the sizing agent, which can not only improve the flexibility, heat resistance and water resistance of the sizing agent treated carbon fiber, but also improve the interface bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid and hot environment; and the sizing agent treated carbon fiber has good fiber opening property after the addition of terminal epoxy polyether silicone oil to the sizing agent.

[0007] In combination with the first aspect, in an optional embodiment of the present application, the terminal epoxy polyether silicone oil comprises at least one of IOTA-EO9000, IOTA-EO11000, IOTA-14000, IOTA-ESM31, IOTA-ESM32, Cheersil 8210-2200, Cheersil 8210-1800, SR-PEX9 and SR-PEX12.

[0008] In the technical scheme, the end epoxy polyether silicone oil is selected from the above-mentioned substances, which can improve the flexibility, heat resistance and water resistance of the carbon fiber treated by the sizing agent, and can improve the interfacial bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid and hot environment.

[0009] In combination with the first aspect, in an optional embodiment of the present application, the emulsifier comprises a water-based epoxy resin emulsifier.

[0010] In the technical scheme, the water-based epoxy resin emulsifier can make the sizing agent emulsion system more stable, and further improve the bonding force between the carbon fiber treated by the sizing agent and the matrix resin.

[0011] Optionally, the water-based epoxy resin emulsifier contains a polyether chain segment in the molecular structure.

[0012] Optionally, the water-based epoxy resin emulsifier has a hydrophilic-lipophilic balance value of 18-24.

[0013] In combination with the first aspect, in an optional embodiment of the present application, the epoxy resin comprises at least one of an E44 type epoxy resin, an E51 type epoxy resin, an E20 type epoxy resin, an E12 type epoxy resin, an F44 type epoxy resin, an F51 type epoxy resin and an F48 type epoxy resin.

[0014] In combination with the first aspect, in an optional embodiment of the present application, the smoothing agent comprises at least one of polyethylene glycol monolaurate, polyethylene glycol monoheptanoate, polyethylene glycol monooctanoate, polyethylene glycol monononanoate, polyethylene glycol dimyristate, polyethylene glycol monotetradecanoate, polyethylene glycol dioctanoate, polyethylene glycol monopalmitate, polyethylene glycol monolinoleate, polyethylene glycol monooleate and polyethylene glycol dioleate.

[0015] In the technical scheme, the smoothing agent is selected from the above-mentioned substances, which can reduce the friction force on the surface of the carbon fiber treated by the sizing agent, so that the carbon fiber can be well dispersed and fully infiltrated in the matrix resin when the composite material is prepared, thereby further improving the bonding force between the carbon fiber treated by the sizing agent and the matrix resin.

[0016] In combination with the first aspect, in an optional embodiment of the present application, the main sizing agent further comprises 5-20 parts of an additive by weight fraction; the additive comprises at least one of triethylamine, tri-n-propylamine, triisopropylamine, N,N-dimethylbenzylamine, N,N-diethylbenzylamine, N,N'-dipropylbenzylamine, triphenylamine, tri(methylphenyl)amine, tri(ethylphenyl)amine, methylpyridine and isoquinoline.

[0017] In the technical solution, when the carbon fiber has oxygen-containing functional groups such as carboxyl and hydroxyl groups, the above-mentioned substance is selected as the additive in the main sizing agent, the additive can combine with the protons in the oxygen-containing functional groups of the carbon fiber, and the oxygen-containing functional groups of the carbon fiber are converted into anion groups, the anion groups of the carbon fiber can undergo nucleophilic reaction with the epoxy groups in the epoxy resin in the sizing agent, so that the carbon fiber is firmly combined with the sizing agent.

[0018] In combination with the first aspect, in an optional implementation of the present application, the mass ratio of the main sizing agent in the sizing agent is 40-60%.

[0019] In the second aspect, the present application provides a preparation method of the sizing agent provided in any one of the first aspect, the preparation method comprising: mixing the main sizing agent in a molten state with an organic solvent to obtain an oily system; and then adding water to the oily system and mixing.

[0020] The preparation method of the sizing agent provided by the present application uses the terminal epoxy polyether silicone oil, which can not only improve the flexibility, heat resistance and water resistance of the carbon fiber treated by the prepared sizing agent, but also improve the interfacial bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid and hot environment; and after adding the terminal epoxy polyether silicone oil in the preparation process of the sizing agent, the carbon fiber treated by the prepared sizing agent has good fiber opening property.

[0021] Optionally, the organic solvent includes an alcohol ether solvent.

[0022] Optionally, the alcohol ether solvent includes at least one of propylene glycol methyl ether and diethylene glycol methyl ether.

[0023] In the third aspect, the present application provides a carbon fiber, comprising a carbon fiber substrate and a coating layer on the surface of the carbon fiber substrate; the coating layer comprises a dried product of the sizing agent provided in any one of the first aspect.

[0024] The carbon fiber provided by the present application has good flexibility, heat resistance and water resistance, and can improve the interfacial bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid and hot environment.

[0025] In the fourth aspect, the present application provides a composite material, comprising a matrix resin and the carbon fiber provided in the third aspect.

[0026] The composite material provided by the present application has high interfacial bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid and hot environment. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation to the scope. For those skilled in the art, other related drawings can also be obtained without creative effort.

[0028] Figure 1 The preparation method flow chart of the sizing agent provided by the present application is shown in the following. DETAILED DESCRIPTION

[0029] The present application provides a sizing agent, the sizing agent is in the form of emulsion, and the sizing agent comprises a main sizing agent and water; wherein the main sizing agent comprises the following components in parts by weight: 20-50 parts of terminal epoxy polyether silicone oil, 25-55 parts of epoxy resin, 10-30 parts of emulsifier and 5-25 parts of smoothing agent.

[0030] The present application adds terminal epoxy polyether silicone oil in the sizing agent, the molecular structure of the terminal epoxy polyether silicone oil has epoxy groups and polyoxyethylene ether chain segments, and the middle chain segment in the molecular structure of the terminal epoxy polyether silicone oil is linear polysiloxane chain segment, which has good flexibility, thereby improving the flexibility of the carbon fiber treated by the sizing agent.

[0031] The present application adds terminal epoxy polyether silicone oil in the sizing agent, which can also improve the heat resistance and water resistance of the carbon fiber treated by the sizing agent, and can also improve the interfacial bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid heat environment; and after adding the terminal epoxy polyether silicone oil in the sizing agent, the carbon fiber treated by the sizing agent has good fiber opening property.

[0032] In addition, the terminal epoxy polyether silicone oil has emulsifying capacity, and is introduced into the sizing agent by compounding with the emulsifier. Since the terminal epoxy polyether silicone oil has epoxy groups, it can react with the epoxy resin as the matrix resin and the amine-based curing agent contained in the matrix resin during the preparation of the composite material, thereby solving the compatibility problem of the carbon fiber treated by the sizing agent and the epoxy resin as the matrix resin, and improving the interfacial bonding strength between the carbon fiber treated by the sizing agent and the epoxy resin as the matrix resin.

[0033] Therefore, the sizing agent provided by the present application can improve the application range of the carbon fiber prepared by using the sizing agent.

[0034] In the present application, the amount of the terminal epoxy polyether silicone oil in the main sizing agent is 20-50 parts; if the amount of the terminal epoxy polyether silicone oil is too small, it cannot effectively improve the flexibility, heat resistance and water resistance of the carbon fiber treated by the sizing agent; if the amount of the terminal epoxy polyether silicone oil is too large, it will have an adverse effect on the compatibility of the carbon fiber and the matrix resin.

[0035] As an example, the weight fraction of the end epoxy polyether silicone oil in the main sizing agent can be any one of 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, and 50 parts or a range value between any two of them.

[0036] In the present application, the amount of the emulsifier in the main sizing agent is 10-30 parts; if the amount of the emulsifier is too small, the sizing agent emulsion system will be unstable; if the amount of the emulsifier is too large, it will affect the subsequent curing rate and hardness of the sizing agent.

[0037] As an example, the weight fraction of the emulsifier in the main sizing agent can be any one of 10 parts, 15 parts, 20 parts, 25 parts, and 30 parts or a range value between any two of them.

[0038] In the present application, the amount of the smoothing agent in the main sizing agent is 5-25 parts; if the amount of the smoothing agent is too small, the carbon fiber cannot be well dispersed and fully infiltrated in the matrix resin when preparing the composite material; if the amount of the smoothing agent is too large, it will reduce the interfacial bonding strength between the carbon fiber treated by the sizing agent and the matrix resin.

[0039] As an example, the weight fraction of the smoothing agent in the main sizing agent can be any one of 5 parts, 10 parts, 15 parts, 20 parts, and 25 parts or a range value between any two of them.

[0040] As an example, the weight fraction of the epoxy resin in the main sizing agent can be any one of 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, and 55 parts or a range value between any two of them.

[0041] In some optional embodiments of the present application, the end epoxy polyether silicone oil includes at least one of IOTA-EO9000, IOTA-EO11000, IOTA-14000, IOTA-ESM31, IOTA-ESM32, Cheersil8210-2200, Cheersil 8210-1800, SR-PEX9, and SR-PEX12.

[0042] The end epoxy polyether silicone oil is selected from the above-mentioned substances, which not only can improve the flexibility, heat resistance, and water resistance of the carbon fiber treated by the sizing agent, but also can improve the interfacial bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid heat environment.

[0043] As an example, the end epoxy polyether silicone oil can be selected from the end epoxy polyether silicone oil IOTA-EO9000.

[0044] In some optional embodiments of the present application, the emulsifier comprises an aqueous epoxy resin emulsifier. The use of the aqueous epoxy resin emulsifier can not only make the sizing agent emulsion system more stable, but also further improve the bonding force between the carbon fiber treated by the sizing agent and the matrix resin.

[0045] In addition, since the aqueous epoxy resin emulsifier has an epoxy group, it can react with the epoxy resin as the matrix resin and the amine-based curing agent contained in the matrix resin during the preparation of the composite material, thereby solving the compatibility problem between the carbon fiber treated by the sizing agent and the epoxy resin as the matrix resin and improving the interfacial bonding strength between the carbon fiber treated by the sizing agent and the epoxy resin as the matrix resin.

[0046] Further, in some optional embodiments of the present application, the aqueous epoxy resin emulsifier contains a polyether segment in the molecular structure. The polyether segment can make the emulsifier hydrophilic, and can make the sizing agent emulsion system more stable.

[0047] In some optional embodiments of the present application, the epoxy resin body in the aqueous epoxy resin emulsifier comprises at least one of an E51 type epoxy resin, an E44 type epoxy resin, and an E20 type epoxy resin.

[0048] For example, the aqueous epoxy resin emulsifier is a modified polyether epoxy resin emulsifier, for example, the aqueous epoxy resin emulsifier can be selected from an aqueous epoxy resin emulsifier JT-801.

[0049] In some optional embodiments of the present application, the aqueous epoxy resin emulsifier has a hydrophilic-lipophilic balance value of 18-24, which can make the sizing agent emulsion system more stable.

[0050] In some optional embodiments of the present application, the epoxy resin comprises at least one of an E44 type epoxy resin, an E51 type epoxy resin, an E20 type epoxy resin, an E12 type epoxy resin, an F44 type epoxy resin, an F51 type epoxy resin, and an F48 type epoxy resin.

[0051] It should be noted that the epoxy resin is not limited to the above-mentioned substances, and any commonly used epoxy resin in the sizing agent can be used.

[0052] In some optional embodiments of the present application, the smoothing agent comprises at least one of polyethylene glycol monolaurate, polyethylene glycol monoheptanoate, polyethylene glycol monocaprylate, polyethylene glycol monononanoate, polyethylene glycol dimyristate, polyethylene glycol monopentadecanoate, polyethylene glycol monomyristate, polyethylene glycol dioctanoate, polyethylene glycol monopalmitate, polyethylene glycol monolinoleate, polyethylene glycol monooleate, and polyethylene glycol dioleate.

[0053] The smooth agent is selected from the above-mentioned substances, which can not only reduce the friction of the carbon fiber surface after the sizing agent treatment, but also make the carbon fiber well dispersed and fully infiltrated in the matrix resin during the preparation of the composite material, thereby further improving the bonding force between the carbon fiber after the sizing agent treatment and the matrix resin.

[0054] In some optional embodiments of the present application, the main sizing agent further comprises 5-20 parts of an additive by weight; the additive comprises at least one of triethylamine, tri-n-propylamine, triisopropylamine, N,N-dimethylbenzylamine, N,N-diethylbenzylamine, N,N'-dipropylbenzylamine, triphenylamine, tri(methylphenyl)amine, tri(ethylphenyl)amine, methylpyridine and isoquinoline.

[0055] When the carbon fiber has oxygen-containing functional groups such as carboxyl and hydroxyl groups, the main sizing agent adds the above-mentioned additive, the above-mentioned additive can combine the protons in the oxygen-containing functional groups in the carbon fiber, and make the oxygen-containing functional groups in the carbon fiber into anionic groups, the anionic groups in the carbon fiber can have a nucleophilic reaction with the epoxy groups in the epoxy resin in the sizing agent, so that the carbon fiber is firmly combined with the sizing agent.

[0056] In some optional embodiments of the present application, the mass fraction of the main sizing agent in the sizing agent is 40-60%.

[0057] For example, the mass fraction of the main sizing agent in the sizing agent can be any one of 40%, 45%, 50%, 55% and 60% or a range value between any two of them.

[0058] The present application provides a preparation method of the above-mentioned sizing agent, which comprises: first mixing the main sizing agent in a molten state with an organic solvent to obtain an oily system; then adding water to the oily system and second mixing to obtain an intermediate emulsion; removing the organic solvent in the intermediate emulsion.

[0059] It should be noted that the components of the main sizing agent used in the preparation method are selected and the amount ratio of the components in the sizing agent is the same as the aforementioned component selection of the main sizing agent and the amount ratio of the components in the sizing agent, which will not be repeated here.

[0060] The end epoxy polyether silicone oil used in the preparation method of the sizing agent provided by the present application can not only improve the flexibility, heat resistance and water resistance of the carbon fiber treated by the prepared sizing agent, but also improve the interfacial bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid and hot environment; and after adding the end epoxy polyether silicone oil in the preparation process of the sizing agent, the carbon fiber treated by the prepared sizing agent has good fiber opening property.

[0061] In addition, the sizing agent is prepared by the phase inversion method, the preparation process is simple and easy to implement, the cost is low, and the sizing agent is suitable for large-scale production.

[0062] Figure 1 For the preparation method of the sizing agent provided in the present application, please refer to the flow chart Figure 1 The preparation method of the sizing agent comprises the following steps:

[0063] S110, the main sizing agent in a molten state is mixed with an organic solvent for the first time to obtain an oily system.

[0064] In some optional embodiments of the present application, the organic solvent comprises an alcohol ether solvent, and the main sizing agent can be fully dissolved and diluted.

[0065] Further, the alcohol ether solvent comprises at least one of propylene glycol methyl ether and diethylene glycol methyl ether.

[0066] In some optional embodiments of the present application, the mass ratio of the main sizing agent in a molten state to the organic solvent is 1:(0.05-0.15).

[0067] S120, water is added to the oily system and mixed for the second time.

[0068] In some optional embodiments of the present application, water is added to the oily system during the first stirring of the oily system.

[0069] Further, the rotating speed of the first stirring is 2000-4000 r / min.

[0070] In some optional embodiments of the present application, the second mixing adopts second stirring, the rotating speed of the second stirring is 2000-4000 r / min, and the time of the second stirring is 20-40 min.

[0071] In some optional embodiments of the present application, since the amount of the organic solvent is small, the organic solvent can be naturally volatilized and removed in the S120 step, and there is no need to additionally remove the organic solvent.

[0072] In other feasible embodiments of the present application, the operation of removing the organic solvent can also be performed after the S120 step.

[0073] It should be noted that the specific removal method of the organic solvent is not limited in the present application, for example, rotary evaporation can be used.

[0074] The present application further provides a carbon fiber, which comprises a carbon fiber substrate and a coating layer on the surface of the carbon fiber substrate; the coating layer comprises the dried product of the sizing agent provided in the present application.

[0075] The carbon fiber provided by the application has good flexibility, heat resistance and water resistance, and can improve the interfacial bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid heat environment; and the carbon fiber provided by the application is suitable for processing processes such as prepreg, woven cloth, net tire, needling, and has a wide application range.

[0076] For example, the material of the carbon fiber substrate can be polyacrylonitrile; it should be noted that the material of the carbon fiber substrate is not limited in the application.

[0077] The application further provides a composite material comprising a matrix resin and the carbon fiber provided above.

[0078] The composite material provided by the application has high interfacial bonding strength of the composite material formed by the carbon fiber and the matrix resin in a humid heat environment.

[0079] For example, the matrix resin can be epoxy resin and the like.

[0080] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0081] Example 1

[0082] The present embodiment provides a sizing agent, which is prepared by the following steps:

[0083] (1) 250g of terminal epoxy polyether silicone oil IOTA-EO9000 (i.e. terminal epoxy polyether silicone oil), 150g of water-based epoxy resin emulsifier JT-801 (i.e. emulsifier), 330g of E51 type epoxy resin (i.e. epoxy resin), 120g of polyethylene glycol monolaurate (i.e. smoothing agent) and 150g of triethylamine (i.e. additive) are added to a reactor equipped with a stirrer, heated to 80℃ and stirred to fully melt the system. Then 20g of a mixed solvent of propylene glycol methyl ether and diethylene glycol methyl ether with a volume ratio of 1:1 is added to the molten system, and the mixture is uniformly mixed to obtain an oily system.

[0084] (2) In the process of stirring the oily system at a speed of 3000r / min, 1000g of deionized water is slowly added to the oily system to obtain an emulsion system; then deionized water is continuously added to the emulsion system, and then stirred at a speed of 3000r / min for 30min to obtain a sizing agent.

[0085] The total mass of the terminal epoxy polyether silicone oil, the epoxy resin, the emulsifier, the smoothing agent and the additive accounts for 50% of the total mass of the sizing agent.

[0086] Example 2

[0087] The example provides a sizing agent, and the difference between the example and example 1 is that the terminal epoxy polyether silicone oil IOTA-EO9000 is replaced by Cheersil 8210-1800 terminal epoxy polyether active silicone oil.

[0088] Example 3

[0089] The example provides a sizing agent, and the difference between the example and example 1 is that the amount of terminal epoxy polyether silicone oil IOTA-EO9000 is changed to 200g, and the amount of E51 type epoxy resin is changed to 380g.

[0090] Example 4

[0091] The example provides a sizing agent, and the difference between the example and example 1 is that the amount of terminal epoxy polyether silicone oil IOTA-EO9000 is changed to 500g, and the amount of E51 type epoxy resin is changed to 80g.

[0092] Example 5

[0093] The example provides a sizing agent, and the difference between the example and example 1 is that the water-based epoxy resin emulsifier JT-801 is replaced by the epoxy resin emulsifier SSFH-60.

[0094] Example 6

[0095] The example provides a sizing agent, and the difference between the example and example 1 is that triethylamine is replaced by N,N-dimethylbenzylamine.

[0096] Example 7

[0097] The example provides a sizing agent, and the difference between the example and example 1 is that polyethylene glycol monolaurate is replaced by polyethylene glycol monooleate.

[0098] Comparative Example 1

[0099] The comparative example provides a sizing agent, and the difference between the comparative example and example 1 is that 250g of terminal epoxy polyether silicone oil IOTA-EO9000 is replaced by 250g of E51 type epoxy resin.

[0100] Comparative Example 2

[0101] The comparative example provides a sizing agent, and the difference between the comparative example and example 1 is that the amount of terminal epoxy polyether silicone oil IOTA-EO9000 is changed to 150g, and the amount of E51 type epoxy resin is changed to 430g.

[0102] Comparative Example 3

[0103] The comparative example provides a sizing agent, which is different from example 1 in that the amount of end epoxy polyether silicone oil IOTA-EO9000 is changed to 550 g, and the amount of E51 type epoxy resin is changed to 30 g.

[0104] Comparative example 4

[0105] The comparative example provides a sizing agent, which is different from example 1 in that the end epoxy polyether silicone oil IOTA-EO9000 is changed to polyether modified silicone oil P875564 (without end epoxy group).

[0106] Experimental example

[0107] The sizing agents prepared in examples 1-7 and comparative examples 1-4 are diluted with deionized water (the total mass percentage of “end epoxy polyether silicone oil, epoxy resin, emulsifier, smoothing agent and additive” in the diluent is 1%), and the diluted sizing agent is attached to carbon fiber tows (T700x12K) by the infiltration method. Then the carbon fiber tows are taken out and dried at 200°C to obtain sized carbon fibers. The sized carbon fibers are compounded with an epoxy resin matrix to prepare a composite material.

[0108] The sizing agents prepared in examples 1-7 and comparative examples 1-4 are tested for emulsion particle size and emulsion stability, the sized carbon fibers are tested for hardness, heat resistance, hairiness and opening rate, and the composite material is tested for interlaminar shear strength at room temperature and water resistance, and the test results are shown in Table 1 and Table 2.

[0109] The emulsion particle size of the sizing agent is tested by a laser particle size analyzer (model Microtrac S3500).

[0110] The emulsion stability of the sizing agent is tested as follows: the sizing agent is left to stand for 1 month, and the emulsion stability is observed; “emulsion without stratification and no precipitation” is excellent in stability, “emulsion without stratification but with precipitation” is good in stability, and “emulsion with stratification and precipitation” is poor in stability.

[0111] The hardness, hairiness and opening rate of the sized carbon fibers are tested according to the test methods for hardness, hairiness and opening rate in “Carbon Fiber and Graphite Fiber”.

[0112] The heat resistance of the sized carbon fibers is tested as follows: the sized carbon fibers are heated by temperature rise, and the temperature corresponding to a 5% weight reduction of the sized carbon fibers (recorded as critical temperature) is recorded; the greater the critical temperature, the better the heat resistance of the sized carbon fibers.

[0113] The interlaminar shear strength of the composite material is measured according to GB / T 30969 at 23℃ (denoted as the interlaminar shear strength at 23℃).

[0114] The test procedure for the water resistance of the composite material is as follows: the composite material is placed in water and boiled at 90℃ for 72h, and then the interlaminar shear strength of the composite material is measured according to GB / T 30969 (denoted as the interlaminar shear strength after high-temperature and high-humidity treatment). The lower the proportion of the decrease of the interlaminar shear strength after high-temperature and high-humidity treatment relative to the interlaminar shear strength at 23℃, the stronger the water resistance of the composite material.

[0115] Table 1

[0116]

[0117]

[0118] Table 2

[0119]

[0120] In Table 2, the interlaminar shear strength loss rate (%) after high-temperature and high-humidity treatment = [(M1-M2) / M1]x100%.

[0121] As can be seen from Table 1, the sized carbon fibers prepared by using the sizing agents of Examples 1-7 have high flexibility, heat resistance, wear resistance and fiber opening property, and the comprehensive performance of the sized carbon fibers prepared by using the sizing agents of Examples 1-7 is superior to that of the sized carbon fibers prepared by using the sizing agents of Comparative Examples 1-4.

[0122] As can be seen from Table 2, the interfacial bonding strength of the composite material prepared by using the sizing agents of Examples 1-7 in a humid and hot environment is higher than that of the composite material prepared by using the sizing agents of Comparative Examples 1-4 in a humid and hot environment.

[0123] In summary, by adding the terminal epoxy polyether silicone oil to the sizing agent, the flexibility, heat resistance and water resistance of the carbon fibers treated by the sizing agent can be improved, and the interfacial bonding strength of the composite material formed by the carbon fibers and the matrix resin in a humid and hot environment can also be improved; and after adding the terminal epoxy polyether silicone oil to the sizing agent, the carbon fibers treated by the sizing agent have good fiber opening property.

[0124] The above-described embodiments are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

Claims

1. A sizing agent, characterized by, The sizing agent is in the form of an emulsion, and the sizing agent comprises a main sizing material and water; the main sizing material comprises the following components in parts by weight: The end epoxy polyether silicone oil 20-50 parts, epoxy resin 25-55 parts, emulsifier 10-30 parts and smoothing agent 5-25 parts.

2. The sizing agent according to claim 1, characterized by The end epoxy polyether silicone oil comprises at least one of IOTA-EO9000, IOTA-EO11000, IOTA-EO14000, IOTA-ESM31, IOTA-ESM32, Cheersil 8210-2200, Cheersil 8210-1800, SR-PEX9 and SR-PEX12.

3. The sizing agent according to claim 1 or 2, characterized in that, The emulsifier comprises an aqueous epoxy resin emulsifier.

4. The sizing agent according to claim 3, characterized by The aqueous epoxy resin emulsifier contains a polyether chain segment in the molecular structure.

5. The sizing agent according to claim 3, characterized by The aqueous epoxy resin emulsifier has a hydrophilic-lipophilic balance value of 18-24.

6. The sizing agent according to claim 1 or 2, characterized by, The epoxy resin comprises at least one of E44 type epoxy resin, E51 type epoxy resin, E20 type epoxy resin, E12 type epoxy resin, F44 type epoxy resin, F51 type epoxy resin and F48 type epoxy resin.

7. The sizing agent according to claim 1 or 2, characterized by, The smoothing agent comprises at least one of polyethylene glycol monolaurate, polyethylene glycol monoheptanoate, polyethylene glycol monocaprylate, polyethylene glycol monononanoate, polyethylene glycol dilaurate, polyethylene glycol monopentadecanoate, polyethylene glycol monomyristate, polyethylene glycol dioctanoate, polyethylene glycol monopalmitate, polyethylene glycol monolinoleate, polyethylene glycol monooleate and polyethylene glycol dioleate.

8. The sizing agent according to claim 1 or 2, characterized by, The main sizing material further comprises an additive 5-20 parts by weight; The additive comprises at least one of triethylamine, tri-n-propylamine, triisopropylamine, N,N-dimethylbenzylamine, N,N-diethylbenzylamine, N,N'-dipropylbenzylamine, triphenylamine, tri(methylphenyl)amine, tri(ethylphenyl)amine, methylpyridine and isoquinoline.

9. The sizing agent according to claim 1 or 2, characterized by, The mass fraction of the main sizing material in the sizing agent is 40-60%.

10. A method for producing the sizing agent as claimed in any one of claims 1 to 9, characterized by, Comprise: The main sizing material in a molten state is first mixed with an organic solvent to obtain an oily system; then the water is added to the oily system and secondly mixed.

11. The method of claim 10, wherein the sizing agent is prepared by the steps of: The organic solvent comprises an alcohol ether solvent.

12. The method of claim 11, wherein the sizing agent is prepared by the steps of: The alcohol ether solvent comprises at least one of propylene glycol methyl ether and diethylene glycol methyl ether.

13. A carbon fiber, characterized by, Comprise a carbon fiber substrate and a coating layer on the surface of the carbon fiber substrate; the coating layer comprises a dried product of the sizing agent according to any one of claims 1-9.

14. A composite material, characterized by Comprise a base resin and the carbon fiber according to claim 13.

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