Surfactant, preparation method thereof, sizing agent, carbon fiber bundle and composite material

Abstract

The invention discloses a surfactant, a preparation method thereof, a sizing agent, a carbon fiber bundle and a composite material, and relates to the technical field of carbon fiber materials. The structural formula of the surfactant is # imgabs 0 # and / or # imgabs 1 #; wherein Rf (CH2) n is at least one C3-C12 alkyl group in which a hydrogen atom directly connected with a carbon atom is substituted by a fluorine atom; r1 is a hydrocarbylene group; r2 is a hydrogen atom or a C1-C2 alkyl group; and (AO) m is a polyether of a C2-C4 alkyleneoxy group. The fluorine-containing polyurethane surfactant provided by the invention has extremely low surface energy and has good affinity with waterborne polyurethane, and the surface tension of the sizing agent prepared by compounding is as low as 40 mN / m or below. The sizing agent has excellent permeability among carbon fiber bundles, the sized fiber bundles have excellent process processability, and bonding of carbon fibers and matrix resin can be fully enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber materials, in particular to a surfactant, a preparation method thereof, a sizing agent using the surfactant, a carbon fiber bundle using the sizing agent, and a carbon fiber reinforced resin-based composite material. Background Art

[0002] Compared with carbon fiber reinforced thermosetting composites, carbon fiber reinforced thermoplastic composites have the advantages of strong impact resistance, short molding cycle and recyclable waste, and have attracted much attention in the context of "carbon neutrality and carbon peak". The rapid development of engineering thermoplastic resins such as polyamide, thermoplastic polyester, thermoplastic polyurethane, polycarbonate, etc., provides more possibilities for the selection of resin-based composite materials.

[0003] In the process of carbon fiber product processing and composite material molding, the role of sizing agent is crucial. It can not only give carbon fiber processability and protect its surface activity, but also improve the wettability of carbon fiber to matrix resin, thereby improving the comprehensive performance of composite materials. At present, most of the carbon fiber products on the market use sizing agents that are only compatible with thermosetting matrix resins. If they are directly compounded with thermoplastic matrix resins, the mechanical properties are difficult to meet the requirements. Using water-based polyurethane resins that match engineering thermoplastic resins well as film-forming materials for sizing agents can give full play to the reinforcing properties of carbon fibers.

[0004] Among them, waterborne polyurethane has the advantages of good wear resistance, strong adhesion, high toughness and good compatibility with a variety of resins. Therefore, many documents use this type of waterborne resin as the main film-forming material of the sizing agent to improve the wettability of the carbon fiber and the matrix resin after sizing. However, in the process of sizing the carbon fiber bundle, the sizing agent is required to fully wet the surface of the fiber bundle and penetrate between the monofilaments, so as to evenly cover the fiber surface after drying. In the process of studying the surface energy of carbon fiber, the inventor found that for the unsizing carbon fiber after surface treatment (unless otherwise specified, hereinafter referred to as unsizing carbon fiber), the surface energy measured by the Wilhelmy hanging plate method is generally below 40 mN / m, while the surface energy of the waterborne polyurethane resin is generally in the range of 40~55 mN / m, so it is difficult to effectively wet the carbon fiber bundle. In particular, for a tow with a relatively large number of fibers, it is easy to produce uneven coverage of the sizing agent, and then produce more fuzzing and broken wire problems during the process, affecting the performance of the composite material.

[0005] In order to improve the permeability of the sizing agent to the fiber bundle and fully suppress fuzzing and broken fibers, there are also documents that use compounds such as polyoxyalkylene alkyl ethers and aliphatic alcohol alkylene oxide adducts with specific structures. However, the above compounds may have insufficient affinity with waterborne polyurethane, thus limiting the performance of their surface activity. In addition, the above compounds account for a large proportion of the non-volatile components of the sizing agent, which may have an adverse effect on the adhesion between the carbon fiber and the matrix resin after sizing.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The object of the present invention is to provide a surfactant, a preparation method thereof, a sizing agent, a carbon fiber bundle and a composite material.

[0008] The present invention is achieved in that: In a first aspect, the present invention provides a surfactant, the structural formula of which is at least one of formula (1) and formula (2): (1) (2); Among them, R f (CH2) n It is a C3~C12 hydrocarbon group in which at least one hydrogen atom directly connected to the carbon atom is replaced by a fluorine atom, and n represents the number of methylene groups, n=1~2; R1 is an alkylene group directly connected to two isocyanate groups in a diisocyanate molecule; R2 is a hydrogen atom or a C1~C2 hydrocarbon group; (AO) m It is a polyether of C2~C4 alkyleneoxy, m represents the number average added mole number of alkyleneoxy, m=4~180; In an optional embodiment, the R f (CH2) n A C3-C12 aliphatic or aromatic hydrocarbon group in which at least one hydrogen atom directly connected to a carbon atom is replaced by a fluorine atom; Preferably, the aliphatic hydrocarbon group includes 3,3-difluoropropyl, 3,3,3-trifluoropropyl, 4,4,4-trifluoro-2-butenyl, 3,3,4,4,4-pentafluorobutyl, 2,2,3,3,4,4,4-heptafluorobutyl, 5,5,5-trifluoropentyl, 4,4,5,5,5-pentafluoropentyl, 3,3,4,4,5,5,5-heptafluoropentyl, 2,2,3,3,4,4,5,5-octafluoropentyl, 1H,1H-perfluoropentyl, 1H,1H,2H,2H-perfluorohexyl, 1H,1 H-perfluorohexyl, 1H,1H,7H-perfluoroheptyl, 1H,1H-perfluoroheptyl, 1H,1H,2H,2H-perfluorooctyl, 1H,1H,8H-perfluorooctyl, 1H,1H-perfluorooctyl, 1H,1H,2H,2H,3H,3H-perfluorononyl, 1H,1H,9H-perfluorononyl, 1H,1H-perfluorononyl, 1H,1H,2H,2H-perfluorodecyl, 1H,1H-perfluorodecyl, 1H,1H,11H-perfluoroundecyl or 1H,1H-perfluorododecyl; Preferably, the aromatic hydrocarbon group includes 2-fluorobenzyl, 4-fluorobenzyl, 2-fluoro-4-methylbenzyl, 4-(4-fluorophenyl)benzyl, 2,5-difluorobenzyl, 3,5-difluorobenzyl, 2,6-difluorobenzyl, 3,4,5-trifluorobenzyl, 2,3,4,5,6-pentafluorobenzyl, 3-(trifluoromethyl)-benzyl, 2-(trifluoromethyl)-benzyl, 4-(trifluoromethyl)-benzyl or 2-fluoro-6-methylbenzyl; Preferably, the R f (CH2) n A C3-C12 aliphatic hydrocarbon group in which at least three hydrogen atoms directly connected to carbon atoms are replaced by fluorine atoms; Preferably, the R f (CH2) n A C4-C8 aliphatic hydrocarbon group in which at least 5 hydrogen atoms directly connected to carbon atoms are replaced by fluorine atoms; Preferably, the R f (CH2) n It is at least one of 1H,1H,2H,2H-perfluorohexyl, 1H,1H-perfluorohexyl, 1H,1H,2H,2H-perfluorooctyl and 1H,1H-perfluorooctyl.

[0009] In an optional embodiment, the R f (CH2) n It is introduced into the macromolecule of the surfactant by bonding the active hydrogen-containing group directly connected thereto to one isocyanate group of the diisocyanate; Preferably, the active hydrogen-containing group includes a hydroxyl group or an amino group.

[0010] In an optional embodiment, the diisocyanate includes at least one of an aromatic diisocyanate, an aromatic aliphatic diisocyanate, an aliphatic diisocyanate, an alicyclic diisocyanate, and a cycloaliphatic diisocyanate; Preferably, the aromatic diisocyanate includes at least one of toluene-2,6-diisocyanate, toluene-2,4-diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate and dimethyl diphenyl diisocyanate; Preferably, the aromatic aliphatic diisocyanate includes at least one of xylylene diisocyanate and tetramethyl-m-xylylene diisocyanate; Preferably, the aliphatic diisocyanate includes at least one of 1,6-hexamethylene diisocyanate and trimethyl-1,6-hexamethylene diisocyanate; Preferably, the alicyclic diisocyanate includes at least one of isophorone diisocyanate, 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and methylcyclohexyl diisocyanate; Preferably, the cycloaliphatic diisocyanate comprises at least one of cyclohexane dimethylene diisocyanate and norbornane diisocyanate; Preferably, the diisocyanate is toluene-2,6-diisocyanate or toluene-2,4-diisocyanate.

[0011] In an optional embodiment, the (AO) m AO is at least one of ethyleneoxy, propyleneoxy and butyleneoxy; Preferably, the AO is at least one of ethyleneoxy and propyleneoxy; Preferably, m=13~136, more preferably 22~90.

[0012] In a second aspect, the present invention provides a method for preparing a surfactant as described in any one of the aforementioned embodiments, comprising: The diisocyanate is reacted with an organic fluoride containing active hydrogen; then a monofunctional polyether in which the hydroxyl hydrogen is substituted by a methyl group is added to the system for reaction; Wherein, the structural formula of the diisocyanate is The structural formula of the organic fluoride containing active hydrogen is or The structural formula of the monofunctional polyether in which the hydroxyl hydrogen is replaced by a methyl group is .

[0013] In an optional embodiment, the step of reacting the diisocyanate with the organic fluoride containing active hydrogen comprises: adding a catalyst and a solvent to the diisocyanate, heating to 40-60° C., adding the organic fluoride containing active hydrogen dropwise, heating to 60-100° C. after the dropwise addition is completed, reacting for 2-12 hours, determining the isocyanate group content by a di-n-butylamine method, and cooling to below 50° C. after reaching or falling below a first target value; Preferably, the step of adding the monofunctional polyether in which the hydroxyl hydrogen is substituted by methyl to the system for reaction comprises: dripping the monofunctional polyether in which the hydroxyl hydrogen is substituted by methyl, heating to 70-100° C. for aging for 2-12 hours after the dripping is completed, determining the isocyanate group content by a di-n-butylamine method, terminating the reaction when the isocyanate group content reaches or is lower than a second target value, and removing the solvent to obtain a target surfactant; Preferably, the molar ratio of the diisocyanate to the organic fluoride containing active hydrogen is 1:0.5-1.5; Preferably, the molar ratio of the remaining isocyanate groups in the system to the monofunctional polyether in which the hydroxyl hydrogen is substituted by a methyl group is 1:1; Preferably, the first target value is 25-75% of the initial molar number of isocyanate groups, and the second target value is 0; Preferably, the mass ratio of the diisocyanate, the catalyst and the solvent is 1:0~0.02:0~20; Preferably, the catalyst comprises at least one of a tertiary amine catalyst and an organometallic catalyst; Preferably, the tertiary amine catalyst includes at least one of triethylenediamine, bis(dimethylaminoethyl)ether and dimethylethanolamine; Preferably, the organometallic catalyst includes at least one of dibutyltin dilaurate and stannous octoate; Preferably, the solvent comprises at least one of acetone, 2-butanone, ethyl acetate, toluene, dimethylformamide and methylpyrrolidone; Preferably, the solvent comprises at least one of acetone and 2-butanone.

[0014] In a third aspect, the present invention provides a sizing agent, comprising a non-volatile component at a concentration of 0.1 to 20 wt.% and a volatile component at a concentration of 80 to 99.9 wt.%; in terms of mass percentage of the sizing agent, the non-volatile component comprises 0.001 to 0.5 wt.% of a surfactant and 0.099 to 19.999 wt.% of an aqueous polyurethane; the surfactant is a surfactant as described in any one of the above inventions, or is prepared by the preparation method of a surfactant as described in any one of the above inventions; Preferably, the surface tension of the sizing agent is 40-25 mN / m, preferably 35-25 mN / m, and more preferably 32-28 mN / m; And / or, the average particle size of the sizing agent is 1000 nm or less, preferably 500 nm or less, and more preferably 300 nm or less.

[0015] In a fourth aspect, the present invention provides a carbon fiber bundle, comprising a raw carbon fiber bundle and the sizing agent described in the aforementioned embodiment, wherein the sizing agent is attached to the raw carbon fiber bundle, and the attachment amount of the sizing agent is 0.1~20 wt.%, preferably 0.1~10 wt.%, of the total weight of the sizing agent and the raw carbon fiber bundle.

[0016] In a fifth aspect, the present invention provides a carbon fiber composite material comprising the aforementioned carbon fiber bundle and a matrix resin.

[0017] The present invention has the following beneficial effects: The fluorine-containing polyurethane surfactant provided by the present invention introduces fluorine elements, so that the fluorine-containing polyurethane surfactant has extremely low surface energy. It can be compounded with aqueous polyurethane to prepare a sizing agent, and the fluorine-containing polyurethane surfactant has a strong affinity with aqueous polyurethane, which is conducive to the development of its surface activity. When the addition amount of the fluorine-containing polyurethane surfactant is as low as 0.01 wt.%, the surface tension of the sizing agent can be reduced to less than 40 mN / m, and the adhesion between the carbon fiber and the matrix resin after sizing will not be adversely affected. The sizing agent has excellent permeability between carbon fiber bundles, and forms a uniform and smooth film on the surface of the carbon fiber, so that the fiber bundle after sizing has excellent processability, and has a strong adhesion to the matrix resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A surface tension curve of the aqueous solution of the surfactant A1 provided in Example 1 of the present invention; Figure 2 Scanning electron microscope images of carbon fibers after sizing with the sizing agent provided in Example 1 and Comparative Example 1 of the present invention, wherein (a) is a scanning electron microscope image of Example 1, and (b) is a scanning electron microscope image of Comparative Example 1. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0021] The present invention provides a surfactant, the structural formula of which is at least one of formula (1) and formula (2): (1) (2); Among them, R f (CH2) n It is a C3~C12 hydrocarbon group in which at least one hydrogen atom directly connected to the carbon atom is replaced by a fluorine atom, and n represents the number of methylene groups, n=1~2; R1 is an alkylene group directly connected to two isocyanate groups in a diisocyanate molecule; R2 is a hydrogen atom or a C1~C2 hydrocarbon group; (AO) m It is a polyether of C2~C4 alkyleneoxy groups, m represents the number average added mole number of alkyleneoxy groups, and m=4~180.

[0022] In the present invention, by introducing R f (CH2) n and (AO) m , where R f (CH2) n It has extremely low surface energy. When the addition amount of fluorinated polyurethane surfactant is as low as 0.01 wt.%, the surface tension of the sizing agent can be reduced to below 40 mN / m, which will not adversely affect the adhesion between the carbon fiber and the matrix resin after sizing.

[0023] Specifically, in the present invention, R f (CH2) n A C3-12 aliphatic or aromatic hydrocarbon group in which at least one hydrogen atom directly connected to a carbon atom is replaced by a fluorine atom; Preferably, the aliphatic hydrocarbon group includes, but is not limited to, 3,3-difluoropropyl, 3,3,3-trifluoropropyl, 4,4,4-trifluoro-2-butenyl, 3,3,4,4,4-pentafluorobutyl, 2,2,3,3,4,4,4-heptafluorobutyl, 5,5,5-trifluoropentyl, 4,4,5,5,5-pentafluoropentyl, 3,3,4,4,5,5,5-heptafluoropentyl, 2,2,3,3,4,4,5,5-octafluoropentyl, 1H,1H-perfluoropentyl, 1H,1H,2H,2H-perfluorohexyl, 1H, 1H-perfluorohexyl, 1H,1H,7H-perfluoroheptyl, 1H,1H-perfluoroheptyl, 1H,1H,2H,2H-perfluorooctyl, 1H,1H,8H-perfluorooctyl, 1H,1H-perfluorooctyl, 1H,1H,2H,2H,3H,3H-perfluorononyl, 1H,1H,9H-perfluorononyl, 1H,1H-perfluorononyl, 1H,1H,2H,2H-perfluorodecyl, 1H,1H-perfluorodecyl, 1H,1H,11H-perfluoroundecyl or 1H,1H-perfluorododecyl; Preferably, the aromatic hydrocarbon group includes, but is not limited to, 2-fluorobenzyl, 4-fluorobenzyl, 2-fluoro-4-methylbenzyl, 4-(4-fluorophenyl)benzyl, 2,5-difluorobenzyl, 3,5-difluorobenzyl, 2,6-difluorobenzyl, 3,4,5-trifluorobenzyl, 2,3,4,5,6-pentafluorobenzyl, 3-(trifluoromethyl)-benzyl, 2-(trifluoromethyl)-benzyl, 4-(trifluoromethyl)-benzyl or 2-fluoro-6-methylbenzyl; From the perspective of achieving excellent permeability, R f (CH2) n is a C3-C12 aliphatic hydrocarbon group in which at least three hydrogen atoms directly connected to carbon atoms are replaced by fluorine atoms; preferably, R f (CH2) n is a C4-C8 aliphatic hydrocarbon group in which at least 5 hydrogen atoms directly connected to carbon atoms are replaced by fluorine atoms; for example, R f (CH2) n The group may be at least one of 1H,1H,2H,2H-perfluorohexyl, 1H,1H-perfluorohexyl, 1H,1H,2H,2H-perfluorooctyl and 1H,1H-perfluorooctyl.

[0024] In some embodiments of the present invention, R f (CH2) n The active hydrogen-containing group is introduced into the macromolecule of the surfactant by bonding with one isocyanate group in the diisocyanate through the active hydrogen-containing group directly connected thereto; from the viewpoint of reaction controllability and economy, preferably, the active hydrogen-containing group includes a hydroxyl group or an amino group.

[0025] In some embodiments of the present invention, the diisocyanate is a compound containing two isocyanate groups (-N=C=O, hereinafter referred to as NCO) in the molecule. The diisocyanate may include, for example, at least one of aromatic diisocyanate, aromatic aliphatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate and cycloaliphatic diisocyanate, or a mixture of two or more thereof.

[0026] Preferably, the aromatic diisocyanate includes but is not limited to at least one of toluene-2,4-diisocyanate (2,4-TDI), toluene-2,6-diisocyanate (2,6-TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), and dimethyl diphenyl diisocyanate (TODI); Preferably, the aromatic aliphatic diisocyanate includes but is not limited to at least one of xylylene diisocyanate (XDI) and tetramethyl meta-xylylene diisocyanate (TMXDI); Preferably, the aliphatic diisocyanate includes but is not limited to at least one of 1,6-hexamethylene diisocyanate (HDI) and trimethyl-1,6-hexamethylene diisocyanate (TMHDI); Preferably, the alicyclic diisocyanate includes but is not limited to at least one of isophorone diisocyanate (IPDI), 1,4-cyclohexane diisocyanate (CHDI), dicyclohexylmethane diisocyanate (HMDI), and methylcyclohexyl diisocyanate (HTDI); Preferably, the cycloaliphatic diisocyanate includes but is not limited to at least one of cyclohexane dimethylene diisocyanate (HXDI) and norbornane diisocyanate (NB-DI); As the above-mentioned diisocyanate, from the viewpoint of synthetic controllability, aromatic diisocyanates and aromatic aliphatic diisocyanates having two isocyanate groups with a large difference in reactivity due to inductive effect and / or steric effect are preferred, and aromatic diisocyanates having two isocyanate groups directly connected to the same aromatic ring are more preferred, and toluene-2,4-diisocyanate (2,4-TDI) and toluene-2,6-diisocyanate (2,6-TDI) are further preferred, and toluene-2,4-diisocyanate (2,4-TDI) is most preferred.

[0027] In some embodiments of the present invention, (AO) m AO is at least one of ethyleneoxy, propyleneoxy and butyleneoxy; preferably, AO is at least one of ethyleneoxy and propyleneoxy.

[0028] m represents the number average added mole number of alkyleneoxy groups, and m AOs can be the same type of alkyleneoxy groups or different types of alkyleneoxy groups. When AO is two or more alkyleneoxy groups, it can be a random combination, a block combination, or a combination of the two. Among them, a random combination refers to a combination formed by random and irregular arrangement of two or more monomers during the polymerization process; a block combination refers to a combination formed by alternating arrangement of two or more polymer chain segments with different chemical structures.

[0029] From the viewpoint of improving the solubility and permeability of the surfactant (A), a combination of ethyleneoxy groups alone and a block combination of ethyleneoxy groups and propyleneoxy groups are preferred, and a combination of ethyleneoxy groups alone is more preferred.

[0030] The above-mentioned composition of m AOs can be introduced into the macromolecule of the surfactant through the adduct of a difunctional polyether and a single methanol, or in other words, the composition of m AOs can be introduced into the macromolecule of the surfactant through a monofunctional polyether in which one hydroxyl hydrogen is replaced by a methyl group.

[0031] The number average added mole number of the alkyleneoxy group is m=4 to 180. When m is less than 4, the solubility of the surfactant in water is insufficient, and when m is greater than 180, the permeability of the surfactant is reduced. From the perspective of improving the solubility and permeability of the surfactant (A), the number average added mole number of the alkyleneoxy group is preferably m=13 to 136, and more preferably 22 to 90.

[0032] The surfactant in the present invention may be used alone or as a mixture of two or more.

[0033] In addition, the present invention provides a method for preparing the above-mentioned surfactant, which comprises the following steps: S1. reacting diisocyanate with an organic fluoride containing active hydrogen.

[0034] Specifically, diisocyanate is put into a reactor equipped with a reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle, a trace amount of catalyst and a small amount of solvent are dropped, the temperature is raised to 40-60°C, and an organic fluoride containing active hydrogen is added dropwise. After the addition is completed, the temperature is raised to 60-100°C and the reaction is carried out for 2-12 hours. The isocyanate group content is determined by the di-n-butylamine method. After reaching or falling below the first target value (25-75% of the initial molar number of isocyanate groups), the temperature is lowered to below 50°C.

[0035] Among them, the structural formula of diisocyanate is , the structural formula of the organic fluoride containing active hydrogen is or ; The molar ratio of diisocyanate to organic fluoride containing active hydrogen is 1:0.5~1.5; the mass ratio of diisocyanate, catalyst and solvent is 1:0~0.02:0~20; The catalyst includes at least one of a tertiary amine catalyst and an organic metal catalyst; the tertiary amine catalyst includes at least one of triethylenediamine, bis(dimethylaminoethyl) ether and dimethylethanolamine; the organic metal catalyst includes at least one of dibutyltin dilaurate and stannous octoate; The solvent includes at least one of acetone, 2-butanone, ethyl acetate, toluene, dimethylformamide and methylpyrrolidone; more preferably, the solvent includes at least one of acetone and 2-butanone.

[0036] S2. Then, a monofunctional polyether in which the hydroxyl hydrogen is replaced by a methyl group is added into the system for reaction.

[0037] Specifically, a monofunctional polyether in which the hydroxyl hydrogen is replaced by a methyl group is added dropwise, and after the addition is completed, the temperature is raised to 70-100° C. and aged for 2-12 hours. The isocyanate group content is determined by the di-n-butylamine method. The reaction is terminated when the isocyanate group content reaches or is lower than the second target value (0), and the target surfactant is obtained after removing the solvent.

[0038] The structural formula of the monofunctional polyether in which the hydroxyl hydrogen is replaced by a methyl group is The molar ratio of the remaining isocyanate groups in the system to the monofunctional polyether in which the hydroxyl hydrogen is replaced by a methyl group is 1:1.

[0039] In a third aspect, the present invention provides a sizing agent, comprising a non-volatile component with a concentration of 0.1 to 20 wt.% and a volatile component with a concentration of 80 to 99.9 wt.%; in terms of mass percentage of the sizing agent, the non-volatile component comprises 0.001 to 0.5 wt.% of a surfactant and 0.099 to 19.999 wt.% of an aqueous polyurethane; the surfactant is the surfactant of any one of the aforementioned embodiments, or is prepared by the preparation method of the surfactant of any one of the aforementioned embodiments.

[0040] Among them, the proportion of surfactant in the sizing agent is preferably 0.001-0.5 wt.%, more preferably 0.005-0.2 wt.%, and most preferably 0.01-0.1 wt.%. When the weight ratio is greater than 0.5 wt.%, it is difficult to continuously improve the surface activity of the sizing agent, and it may have a certain negative impact on the interfacial bonding strength of the composite material; on the other hand, when the weight ratio is less than 0.001 wt.%, it is difficult to reduce the surface tension of the sizing agent to less than 40 mN / m, and it is easy to cause uneven coverage of the sizing agent, which in turn causes more fuzzing and broken wire problems in the carbon fiber bundle during the process, which also affects the performance of the composite material.

[0041] The proportion of waterborne polyurethane in the sizing agent is preferably 0.099-19.999 wt.%, more preferably 0.499-9.999 wt.%, and further preferably 0.999-4.999 wt.%; if the weight ratio is lower than 0.099 wt.%, the adhesion between the carbon fiber and the matrix thermoplastic resin after sizing is difficult to meet the requirements; on the other hand, if the weight ratio is higher than 19.999 wt.%, the carbon fiber bundle is difficult to be thin and evenly spread during the process, affecting the impregnation of the matrix resin, which may have an adverse effect on the mechanical properties of the composite material. The non-volatile content test in the present invention adopts the Chinese standard GB / T1725-2007.

[0042] In the present invention, the waterborne polyurethane may be a waterborne polyurethane emulsion or a waterborne polyurethane dispersion; the waterborne polyurethane may be prepared independently or purchased commercially.

[0043] Among them, the self-prepared method is a conventional method, for example, an aqueous polyurethane emulsion is an aqueous emulsion obtained by emulsifying non-hydrophilic polyurethane macromolecules in water by adding an emulsifier; an aqueous polyurethane dispersion is an aqueous dispersion without an emulsifier obtained by introducing a hydrophilic group into a polyurethane macromolecular skeleton containing a terminal. In terms of storage stability and adhesion to the base resin, an aqueous polyurethane dispersion is preferred.

[0044] The chemical composition of the above-mentioned aqueous polyurethane emulsion and / or aqueous polyurethane dispersion is not particularly limited, and examples thereof include compounds composed of polyisocyanates, oligomeric polyols, chain extenders, and necessary cross-linking agents, blocking agents, salt-forming agents, emulsifiers, etc., with water as the dispersed phase, and may contain no or only a small amount of organic solvent.

[0045] As specific examples of the above-mentioned polyisocyanates, in addition to the diisocyanates listed in the surfactant section, it also includes polyisocyanates containing 3 or more NCO groups in the molecule and isocyanate derivatives, which can be listed as polymethylene polyphenyl isocyanate (PAPI), TDI dimer, toluene diisocyanate and trimethylolpropane adduct (TDI-TMP adduct), IPDI trimer, HDI trimer, etc.

[0046] As the polyisocyanate, from the viewpoint of storage stability, aliphatic diisocyanates and alicyclic diisocyanates are preferred, 1,6-hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) are more preferred, and isophorone diisocyanate (IPDI) is most preferred.

[0047] As the above-mentioned oligomer polyol, it is an oligomer of a polycarboxylic acid and a polyol, and there can be mentioned polyester polyols such as polyethylene adipate glycol ester diol, polyethylene phthalate glycol ester diol, polymer-grafted polyester polyols, polycaprolactone diol and polycarbonate diol, etc., polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol ether diol, polyoxypropylene-oxyethylene glycol, etc., and polyester polyether type oligomer polyols containing both polyester structure and polyether structure in the molecule.

[0048] As the above-mentioned oligomer polyol, from the viewpoint of improving the adhesion between the carbon fiber and the matrix resin after sizing, and reducing the viscosity to reduce the use of organic solvents, polyester polyether polyol and polyester polyol are preferred, polyester polyether polyol is more preferred, aromatic polyester polyether polyol is further preferred, and aromatic polyester polyether diol obtained by condensation polymerization of aromatic dicarboxylic acid with aliphatic diol and polyether diol is most preferred.

[0049] The chain extender is a small molecule compound containing two active hydrogen atoms, and examples thereof include 1,4-butanediol, ethylene glycol, diethylene glycol, hexylene glycol, ethylenediamine, hydrazine, hexamethylenediamine, isophoronediamine, and chain extenders containing ions or ionizable groups, such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, sodium ethylenediamine ethanesulfonate, and N-methyldiethanolamine. Chain extenders containing ionizable groups, such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and N-methyldiethanolamine are preferred. Anionic chain extenders such as 2,2-dimethylolpropionic acid and 2,2-dimethylolbutyric acid are further preferred, and 2,2-dimethylolpropionic acid is most preferred.

[0050] The crosslinking agent is a compound containing three or more active hydrogen atoms, and examples thereof include triethanolamine, glycerol, trimethylolpropane, pentaerythritol, diethylenetriamine, triethylenetetramine, and low molecular weight polyether polyols.

[0051] As the above-mentioned blocking agent, it is a compound containing only one active hydrogen, and examples thereof include butanone oxime, caprolactam, phenol, malonate, sodium bisulfite, etc. The above-mentioned blocking agent can block part or all of the NCO groups. After the emulsion is dried to form a film, the NCO groups can be unblocked by heating treatment, reacting with the active hydrogen groups to produce crosslinking, further improving the physical properties of the film-formed material. Since the processing temperature of thermoplastic resins is mostly above 200°C, from the perspective of suitable unblocking temperature and compatibility with the matrix resin, caprolactam and phenol with higher unblocking temperatures are preferred, and caprolactam is further preferred.

[0052] The salt-forming agent is a compound that can form a salt with the chain extender having an ionizable group, and includes sodium hydroxide, ammonia water, triethylamine, hydrochloric acid, glacial acetic acid, etc. For anionic chain extenders, the salt-forming agent is preferably triethylamine.

[0053] The aqueous polyurethane emulsion and / or aqueous polyurethane dispersion may also contain an emulsifier, preferably a nonionic emulsifier; the emulsifier can disperse the non-hydrophilic polyurethane in the aqueous medium, improve the storage stability of the hydrophilic polyurethane, migrate to the surface after film formation, improve the smoothness of the fiber bundle surface, and further inhibit fiber breakage and fuzzing. Examples include ethylene oxide-propylene oxide block copolymers, higher alcohol polyoxyethylene ethers, fatty acid polyoxyethylene esters, alkylphenol polyoxyethylene ethers, and the like.

[0054] The aqueous polyurethane emulsion and / or aqueous polyurethane dispersion may be a composite emulsion / dispersion blended or copolymerized with other polymers, and examples thereof include polyurethane-acrylate composite emulsion / dispersion, polyurethane-epoxy composite emulsion / dispersion, and the like.

[0055] Specific examples of the organic solvent are the same as those given in the section of the surfactant.

[0056] Preferably, the surface tension of the sizing agent is 40 to 25 mN / m, preferably 35 to 25 mN / m, and more preferably 32 to 28 mN / m. The surface tension of the sizing agent in the present invention is measured by a DCAT21 surface tension meter using a platinum plate method when the non-volatile content of the sizing agent is adjusted to 1.0 wt.%.

[0057] In addition, the sizing agent may contain other ingredients besides the above-mentioned surfactant and waterborne polyurethane, such as cosolvent, surfactant, lubricant, defoamer, leveling agent, antioxidant, thixotropic agent and antistatic agent.

[0058] The average particle size of the sizing agent in the present invention is not particularly limited, but is preferably 1000 nm or less, more preferably 500 nm or less, and further preferably 300 nm or less from the viewpoint of storage stability.

[0059] In addition, the present invention provides a carbon fiber bundle, which includes a raw carbon fiber bundle and the above-mentioned sizing agent, the sizing agent is attached to the raw carbon fiber bundle, and the attached amount of the sizing agent is 0.1~20 wt.%, preferably 0.1~10 wt.% of the total weight of the sizing agent and the raw carbon fiber bundle.

[0060] The carbon fiber bundle of the present invention is obtained by attaching the above-mentioned sizing agent to the raw carbon fiber bundle, and is used to strengthen the matrix resin. The raw carbon fiber bundle can be obtained by processing any one of the precursors of rayon, asphalt and polyacrylonitrile. The method of attaching the sizing agent to the raw carbon fiber bundle is not particularly limited, and a roller dipping method, a spraying method, etc. can be used. From the perspective of sizing uniformity, the roller dipping method is preferred. The drying method of the carbon fiber bundle attachment is also not particularly limited, and a contact heating roller drying method, a non-contact hot air drying method, and a combination of the two methods can be used.

[0061] The carbon fiber bundle of the present invention is preferably a carbon fiber bundle in which 3,000 to 50,000 fiber filaments are bundled.

[0062] In the present invention, the carbon fiber bundle with a sizing agent attached has an attached amount of sizing agent of 0.1 to 20 wt.% based on the total weight of the sizing agent and the carbon fiber bundle. For continuous carbon fibers, the attached amount of sizing agent is preferably 0.1 to 10 wt.%, and more preferably 0.5 to 5 wt.%. For chopped carbon fibers (cut to a specified length of 1 to 15 mm), it is preferably 0.5 to 20 wt.%, and more preferably 1.0 to 10 wt.%.

[0063] If the attachment amount of the above-mentioned sizing agent is less than 0.1 wt.%, the fiber bundle will not be sufficiently bundled and the process passability will deteriorate; if the attachment amount is more than 20 wt.%, the fiber bundle will not be sufficiently open and the resin impregnation will deteriorate; as a result, the performance of the composite material cannot be improved, so it is not preferred.

[0064] The method for determining the amount of sizing agent adhesion in the present invention is to use the high temperature decomposition method in the Chinese standard GB / T 29761-2022. Specifically, the fiber bundle is placed in an electric furnace with an inert atmosphere, the temperature is raised to above the decomposition temperature of the sizing agent to remove the sizing agent, and the adhesion amount is calculated based on the weight change before and after.

[0065] Furthermore, the present invention provides a carbon fiber reinforced composite material, which comprises the above carbon fiber bundle and a matrix resin.

[0066] According to the different curing modes, the matrix resin can be divided into thermosetting matrix resin and thermoplastic matrix resin. Among them, the thermosetting matrix resin includes at least one of epoxy resin, unsaturated polyester resin, bismaleimide resin, vinyl resin, phenolic resin and polyurethane resin; the thermoplastic matrix resin includes at least one of polyolefin resin, polyamide resin, thermoplastic polyester resin, polycarbonate resin, ABS resin, polymethyl methacrylate resin, phenoxy resin, polyphenylene sulfide resin, polyether sulfone resin, polyetherimide resin, polyether ether ketone resin and polyether ketone ketone resin.

[0067] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0068] Example 1 This embodiment provides a sizing agent, which includes 0.05 wt.% of surfactant A1, 0.95 wt.% of waterborne polyurethane B1, and 99 wt.% of deionized water. Unless otherwise specified, the weight percentages of surfactant A and waterborne polyurethane B refer to the weight percentages of their non-volatile components in the sizing agent.

[0069] The synthesis method of surfactant A1 includes: weighing 110 parts of polyethylene glycol monomethyl ether (Mn=2000) and placing it in a vacuum drying oven, heating it to 120°C and dehydrating it under reduced pressure for more than 2 hours for use. A 500 mL four-necked flask is equipped with a reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle, adding 9.14 parts of toluene-2,4-diisocyanate, dripping 0.07 parts of dibutyltin dilaurate and 27.5 parts of 2-butanone, stirring and heating to 50°C. Add 18.2 parts of 1H,1H,2H,2H-perfluoro-1-octanol dropwise from the constant pressure dropping funnel, controlling the dropping speed to keep the reaction temperature within 60°C, and heating to 70°C for 6 hours after the dropwise addition is completed. The di-n-butylamine method was used to determine the isocyanate group (NCO) content. When the isocyanate group molar number reached or was lower than 52.4% (i.e., reached or was lower than 0.055 mol) of the initial molar number, the temperature was lowered to 50°C. The above-mentioned polyethylene glycol monomethyl ether (Mn=2000) was taken out, and 41.2 parts of 2-butanone were added to adjust the viscosity so that it was easy to drip. It was added dropwise to a four-necked flask through a constant pressure dropping funnel. After the dripping was completed, the temperature was raised to 70°C and aged for 3 hours. The NCO content was determined by the di-n-butylamine method. The reaction was terminated when the isocyanate group molar number was 0. After removing the solvent, surfactant A1 was obtained, and the structural formula was The surface tension curve of surfactant A1 aqueous solution is shown in Figure 1 It can be seen that with the increase of A1 concentration, the surface tension of the aqueous solution decreases sharply. When the concentration exceeds 1 g / L (0.1 wt.%), the surface tension drops to the minimum, which can be considered to reach the critical micelle concentration. Therefore, the addition amount of surfactant A1 in this embodiment is preferably 0.01~1 g / L (0.001~0.1 wt.%).

[0070] The synthesis method of waterborne polyurethane B1 includes: weighing 50.0 parts of polyester diol (Nanjing Kangsude Chemical Co., Ltd., brand CP-2110, number average molecular weight Mn=1000) into a 500 mL four-necked flask, installing a thermometer, putting it into an oil bath pot and heating it to 120~125°C, and dehydrating it under reduced pressure until no bubbles emerge. Cooling to below 50°C, the four-necked flask is equipped with a reflux condenser and a mechanical stirring paddle, and filled with high-purity nitrogen, respectively weighing 5.37 parts of trimethylolpropane, 5.37 parts of dimethylolpropionic acid, 3.95 parts of neopentyl glycol and 55.6 parts of isophorone diisocyanate and adding them to the reactor, adding 30.0 parts of 2-butanone and stirring for 15 minutes, then dropping 0.06 parts of dibutyltin dilaurate as a catalyst, and heating to 75~80°C for reaction for 3 hours. Cool down to below 40°C, add 4.05 parts of triethylamine and 21.3 parts of 2-butanone, and stir for 0.5h. Increase the stirring speed, add 351 parts of deionized water containing 4.05 parts of diethylenetriamine dropwise through a peristaltic pump, and carry out post-chain extension reaction while emulsifying. Heat to 60°C and remove the solvent 2-butanone under reduced pressure to obtain an aqueous polyurethane dispersion B1 with an average particle size of 148.9 nm and a solid content of about 30%.

[0071] Example 2 This embodiment provides a sizing agent, which includes 0.05 wt.% of surfactant A2, 0.95 wt.% of water-based polyurethane B2, and 99 wt.% of deionized water.

[0072] The synthesis method of surfactant A2 includes: weighing 165 parts of polyethylene glycol monomethyl ether (Mn=3000) and placing it in a vacuum drying oven, heating it to 120°C and dehydrating it under reduced pressure for more than 2 hours for use. A 500 mL four-necked flask is equipped with a reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle, adding 9.14 parts of toluene-2,4-diisocyanate, dripping 0.10 parts of dibutyltin dilaurate and 38.8 parts of 2-butanone, stirring and heating to 50°C. Add 20.0 parts of 1H,1H-perfluoro-1-octanol dropwise from the constant pressure dropping funnel, control the dropping speed to keep the reaction temperature within 60°C, and heat to 70°C for 6 hours after the dropwise addition is completed. The di-n-butylamine method was used to determine the isocyanate group (NCO) content. When the isocyanate group molar number reached or was lower than 52.4% (i.e., reached or was lower than 0.055 mol) of the initial molar number, the temperature was lowered to 50°C. The above-mentioned polyethylene glycol monomethyl ether (Mn=3000) was taken out, and 58.3 parts of 2-butanone were added to adjust the viscosity so that it was easy to drip. It was added dropwise to a four-necked flask through a constant pressure dropping funnel. After the dripping was completed, the temperature was raised to 70°C and aged for 3 hours. The NCO content was determined by the di-n-butylamine method. The reaction was terminated when the isocyanate group molar number was 0. After removing the solvent, surfactant A2 was obtained, and the structural formula was: .

[0073] The synthesis method of waterborne polyurethane dispersion B2 includes: weighing 60.0 parts of polyester diol (Nanjing Kangsude Chemical Co., Ltd., brand CP-2053, number average molecular weight Mn=2000) into a 500 mL four-necked flask, installing a thermometer, putting it into an oil bath pot and heating it to 120~125°C, decompressing and dehydrating until no bubbles emerge. Cooling to below 50°C, the four-necked flask is equipped with a reflux condenser and a mechanical stirring paddle, and filled with high-purity nitrogen, and weighing 6.71 parts of dimethylol propionic acid, 8.27 parts of diethylene glycol and 46.7 parts of isophorone diisocyanate are added to the reactor, adding 2.0 parts of methyl pyrrolidone and stirring for 15 minutes, and then dropping 0.07 parts of dibutyltin dilaurate as a catalyst, heating to 75~80°C and reacting for 3 hours. Heating to 90°C, adding 5.90 parts of caprolactam and reacting for 4 hours to obtain a prepolymer with NCO part blocked. The temperature was lowered to below 40°C, and 5.06 parts of triethylamine, 4.70 parts of methylpyrrolidone and 5.18 parts of triethanolamine were added and stirred for 0.5 h. The stirring speed was increased, and 318 parts of deionized water containing 1.49 parts of ethylenediamine were added dropwise by a peristaltic pump. During emulsification, a post-chain extension reaction was performed to obtain an aqueous polyurethane dispersion B2 with an average particle size of 68.4 nm and a solid content of about 30%.

[0074] Example 3 This embodiment provides a sizing agent, which includes 0.05 wt.% of surfactant A3, 0.95 wt.% of waterborne polyurethane B1, and 99 wt.% of deionized water.

[0075] The synthesis method of surfactant A3 includes: weighing 82.5 parts of polyethylene glycol monomethyl ether (Mn=1500) and placing it in a vacuum drying oven, heating it to 120°C and decompressing it for more than 2 hours for standby use. A reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle are installed in a 500 mL four-necked flask, 9.14 parts of toluene-2,4-diisocyanate are added, 0.05 parts of stannous octoate and 21.0 parts of 2-butanone are dropped, stirring and heating to 50°C. 13.2 parts of 1H,1H,2H,2H-perfluoro-1-hexanol are added dropwise from the constant pressure dropping funnel, the dropping speed is controlled to keep the reaction temperature within 60°C, and after the dropping is completed, the temperature is raised to 70°C for reaction for 6 hours. The di-n-butylamine method was used to determine the isocyanate group (NCO) content. When the isocyanate group molar number reached or was lower than 52.4% (i.e., reached or was lower than 0.055 mol) of the initial molar number, the temperature was lowered to 50°C. The above-mentioned polyethylene glycol monomethyl ether (Mn=1500) was taken out, and 31.4 parts of 2-butanone were added to adjust the viscosity so that it was easy to drip. It was added dropwise to a four-necked flask through a constant pressure dropping funnel. After the dripping was completed, the temperature was raised to 70°C and aged for 3 hours. The NCO content was determined by the di-n-butylamine method. The reaction was terminated when the isocyanate group molar number was 0. After removing the solvent, surfactant A3 was obtained, and the structural formula was: .

[0076] The synthesis method of waterborne polyurethane B1 is the same as that of Example 1.

[0077] Example 4 This embodiment provides a sizing agent, which includes 0.05 wt.% of surfactant A4, 0.95 wt.% of water-based polyurethane B3, and 99 wt.% of deionized water.

[0078] The synthesis method of surfactant A4 includes: weighing 110 parts of polyethylene glycol monomethyl ether (Mn=2000) and placing it in a vacuum drying oven, heating it to 120°C and dehydrating it under reduced pressure for more than 2 hours, and setting it aside. A 500 mL four-necked flask is equipped with a reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle, adding 9.14 parts of toluene-2,4-diisocyanate, dripping 0.07 parts of stannous octoate and 26.8 parts of 2-butanone, stirring and heating it to 50°C. 15.0 parts of 1H,1H-perfluoro-1-hexanol are added dropwise from the constant pressure dropping funnel, and the dropping speed is controlled to keep the reaction temperature within 60°C. After the dropwise addition is completed, the temperature is raised to 70°C and reacted for 6 hours. The isocyanate group (NCO) content is determined by the di-n-butylamine method, and the temperature is lowered to 50°C after reaching or being lower than 52.4% of the initial molar number of the isocyanate group (i.e. reaching or being lower than 0.055 mol). The above polyethylene glycol monomethyl ether (Mn=2000) was taken out, 40.3 parts of 2-butanone was added to adjust the viscosity so that it was easy to drop, and it was added dropwise into a four-necked flask through a constant pressure dropping funnel. After the dropwise addition was completed, the temperature was raised to 70°C and aged for 3 hours. The NCO content was determined by the di-n-butylamine method. The reaction was terminated when the molar number of isocyanate groups was 0. After removing the solvent, surfactant A4 was obtained, and the structural formula was .

[0079] The waterborne polyurethane B3 is a commercial waterborne polyurethane dispersion, and its trade name is: polyester waterborne polyurethane, purchased from Anhui Femtosecond Chemical Co., Ltd., brand FS-1935A.

[0080] Example 5 This embodiment provides a sizing agent, which includes 0.05 wt.% of surfactant A5, 0.95 wt.% of water-based polyurethane B1, and 99 wt.% of deionized water.

[0081] The synthesis method of surfactant A5 includes: weighing 75.0 parts of polyethylene glycol monomethyl ether (Mn=1000) and placing it in a vacuum drying oven, heating it to 120°C and dehydrating it under reduced pressure for more than 2 hours for use. A 500 mL four-necked flask is equipped with a reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle, adding 17.4 parts of toluene-2,6-diisocyanate, dripping 0.05 parts of dibutyltin dilaurate and 21.3 parts of 2-butanone, stirring and heating to 50°C. Add 14.3 parts of 3,3,3-trifluoropropane-1-ol dropwise from the constant pressure dropping funnel, control the dropping speed to keep the reaction temperature within 60°C, and heat to 70°C for 6 hours after the dropwise addition is completed. The di-n-butylamine method was used to determine the isocyanate group (NCO) content. When the isocyanate group molar number reached or was lower than 37.5% (i.e., reached or was lower than 0.075 mol) of the initial molar number, the temperature was lowered to 50°C. The above-mentioned polyethylene glycol monomethyl ether (Mn=1000) was taken out, and 32.0 parts of 2-butanone were added to adjust the viscosity so that it was easy to drip. It was added dropwise into a four-necked flask through a constant pressure dropping funnel. After the dripping was completed, the temperature was raised to 70°C and aged for 3 hours. The NCO content was determined by the di-n-butylamine method. The reaction was terminated when the isocyanate group molar number was 0. After removing the solvent, surfactant A5 was obtained, and the structural formula was: .

[0082] The synthesis method of waterborne polyurethane B1 is the same as that of Example 1.

[0083] Example 6 This embodiment provides a sizing agent, which includes 0.1 wt.% of surfactant A6, 0.9 wt.% of water-based polyurethane B1, and 99 wt.% of deionized water.

[0084] The synthesis method of surfactant A6 includes: weighing 80.0 parts of polyethylene glycol monomethyl ether (Mn=2000) and placing it in a vacuum drying oven, heating it to 120°C and dehydrating it under reduced pressure for more than 2 hours for standby use. A 500 mL four-necked flask is equipped with a reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle, adding 12.2 parts of toluene-2,4-diisocyanate, dripping 0.06 parts of dibutyltin dilaurate and 22.4 parts of 2-butanone, stirring and heating to 40°C. Add 19.9 parts of 1H,1H-heptafluoro-1-butylamine dropwise from the constant pressure dropping funnel, controlling the dropping speed to keep the reaction temperature within 50°C, and heating to 60°C for 2 hours after the dropwise addition is completed. The di-n-butylamine method was used to determine the isocyanate group (NCO) content. When the isocyanate group molar number reached or was lower than 28.6% (i.e., reached or was lower than 0.040 mol) of the initial molar number, the temperature was lowered to 50°C. The above-mentioned polyethylene glycol monomethyl ether (Mn=2000) was taken out, and 33.6 parts of 2-butanone were added to adjust the viscosity so that it was easy to drip. It was added dropwise to a four-necked flask through a constant pressure dropping funnel. After the dripping was completed, the temperature was raised to 70°C and aged for 3 hours. The NCO content was determined by the di-n-butylamine method. The reaction was terminated when the isocyanate group molar number was 0. After removing the solvent, surfactant A6 was obtained, and the structural formula was: .

[0085] The synthesis method of waterborne polyurethane B1 is the same as that of Example 1.

[0086] Example 7 This embodiment provides a sizing agent, which includes 0.5 wt.% of surfactant A7, 4.5 wt.% of water-based polyurethane B1, and 95 wt.% of deionized water.

[0087] The synthesis method of surfactant A7 includes: weighing 80.0 parts of polyethylene glycol monomethyl ether (Mn=2000) and placing it in a vacuum drying oven, heating it to 120°C and dehydrating it under reduced pressure for more than 2 hours for use. A 500 mL four-necked flask is equipped with a reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle, adding 12.2 parts of toluene-2,4-diisocyanate, dripping 0.06 parts of dibutyltin dilaurate and 22.4 parts of 2-butanone, stirring and heating to 50°C. 19.8 parts of pentafluorobenzyl alcohol are added dropwise from the constant pressure dropping funnel, and the dropping speed is controlled to keep the reaction temperature within 60°C. After the dropwise addition is completed, the temperature is raised to 70°C and reacted for 6 hours. The isocyanate group (NCO) content is determined by the di-n-butylamine method, and the temperature is lowered to 50°C after reaching or being lower than 28.6% of the initial molar number of the isocyanate group (i.e. reaching or being lower than 0.040 mol). The above polyethylene glycol monomethyl ether (Mn=2000) was taken out, 33.6 parts of 2-butanone was added to adjust the viscosity so that it was easy to drop, and it was added dropwise into a four-necked flask through a constant pressure dropping funnel. After the dropwise addition was completed, the temperature was raised to 70°C and aged for 3 hours. The NCO content was determined by the di-n-butylamine method. The reaction was terminated when the molar number of isocyanate groups was 0. After removing the solvent, surfactant A7 was obtained, and the structural formula was .

[0088] The synthesis method of waterborne polyurethane B1 is the same as that of Example 1.

[0089] Example 8 This embodiment provides a sizing agent, which includes 0.05 wt.% of surfactant A8, 0.95 wt.% of waterborne polyurethane B1, and 99 wt.% of deionized water.

[0090] The synthesis method of surfactant A8 includes: weighing 160 parts of monofunctional block polyether (Mn=2900) and placing it in a vacuum drying oven, heating it to 120°C and dehydrating it under reduced pressure for more than 2 hours for use. A 500 mL four-necked flask is equipped with a reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle, adding 9.14 parts of toluene-2,4-diisocyanate, dripping 0.09 parts of dibutyltin dilaurate and 37.4 parts of 2-butanone, stirring and heating to 50°C. Add 18.2 parts of 1H,1H,2H,2H-perfluoro-1-octanol dropwise from the constant pressure dropping funnel, controlling the dropping speed to keep the reaction temperature within 60°C, and heating to 70°C for 6 hours after the dropwise addition is completed. The di-n-butylamine method was used to determine the isocyanate group (NCO) content. When the isocyanate group molar number reached or was lower than 52.4% (i.e., reached or was lower than 0.055 mol) of the initial molar number of the isocyanate group, the temperature was lowered to 50°C. The monofunctional block polyether (Mn=2900) was taken out, and 56.0 parts of 2-butanone were added to adjust the viscosity so that it was easy to drop. The mixture was added dropwise to a four-necked flask through a constant pressure dropping funnel. After the dropwise addition was completed, the temperature was raised to 70°C and aged for 3 hours. The NCO content was determined by the di-n-butylamine method. The reaction was terminated when the isocyanate group molar number was 0. After removing the solvent, surfactant A8 was obtained, and the structural formula was: .

[0091] The synthesis method of waterborne polyurethane B1 is the same as that of Example 1.

[0092] Comparative Example 1 This comparative example provides a sizing agent, which includes 1 wt.% of waterborne polyurethane B2 and 99 wt.% of deionized water. The synthesis method of waterborne polyurethane B2 is the same as that of Example 2.

[0093] Comparative Example 2 This comparative example provides a sizing agent, which includes 0.2 wt.% of commercial surfactant D1 (polyether-modified siloxane, BYK-333 from Germany), 0.8 wt.% of waterborne polyurethane B1, and 99 wt.% of deionized water. The synthesis method of waterborne polyurethane B1 is the same as that of Example 1.

[0094] Comparative Example 3 This comparative example provides a sizing agent, which includes 0.2 wt.% of polyurethane surfactant D2, 0.8 wt.% of waterborne polyurethane B1, and 99 wt.% of deionized water. The difference between this comparative example and Example 1 is that the polyurethane surfactant D2 in this comparative example does not contain fluorine, that is, the raw material 1H,1H,2H,2H-perfluoro-1-octanol in Example 1 is replaced by n-octanol.

[0095] Specifically, the preparation method includes: weighing 110 parts of polyethylene glycol monomethyl ether (Mn=2000) and placing them in a vacuum drying oven, heating to 120°C and decompressing and dehydrating for more than 2 hours for standby use. A 500 mL four-necked flask is equipped with a reflux condenser, a thermometer, a constant pressure dropping funnel and a mechanical stirring paddle, adding 9.14 parts of toluene-2,4-diisocyanate, dripping 0.06 parts of dibutyltin dilaurate and 25.1 parts of 2-butanone, stirring and heating to 50°C. 6.51 parts of n-octanol are added dropwise from the constant pressure dropping funnel, and the dropping speed is controlled to keep the reaction temperature within 60°C. After the dropwise addition is completed, the temperature is raised to 70°C and reacted for 6 hours. The isocyanate group (NCO) content is determined by the di-n-butylamine method, and the temperature is lowered to 50°C after reaching or being lower than 52.4% of the initial molar number of the isocyanate group (i.e. reaching or being lower than 0.055 mol). The above polyethylene glycol monomethyl ether (Mn=2000) was taken out, 37.7 parts of 2-butanone was added to adjust the viscosity so that it was easy to drop, and it was added dropwise into a four-necked flask through a constant pressure dropping funnel. After the dropwise addition was completed, the temperature was raised to 70°C and aged for 3 hours. The NCO content was determined by the di-n-butylamine method. The reaction was terminated when the molar number of isocyanate groups was 0. After removing the solvent, a fluorine-free polyurethane surfactant D2 was obtained, and the structural formula was .

[0096] The synthesis method of waterborne polyurethane B1 is the same as that of Example 1.

[0097] Experimental example The sizing agent obtained in the above examples and comparative examples was used to sizing the unsized carbon fiber bundle (12K) through a special test dipping tank, and dried in a drying tower at 120-150° C. for 5-9 minutes to obtain carbon fiber with a sizing amount of about 0.6-0.8wt.%. In the sizing agent, except for ionized water, the weight of the remaining components refers to the weight of non-volatile matter.

[0098] The sizing agents obtained in the above examples and comparative examples were tested, and the test contents included average particle size, surface tension, fuzz content and interface shear strength.

[0099] Among them, the detection method of the average particle size includes: diluting the sizing agent with water to make its non-volatile matter concentration less than 0.1wt.%, using a nanoparticle size and ZETA potential analyzer (Nano ZS90, produced by Malvern Panalytical, UK) to measure the particle size distribution of the sizing agent, selecting three samples with concentrations that differ by one order of magnitude for measurement, and taking the average value of the Z-average particle size.

[0100] The detection method of surface tension includes: using a mechanical surface tension meter (DCAT21, produced by Dataphysics, Germany) to measure the surface tension of the sizing agent, the test method adopts the platinum plate method, and taking the average value of three measured values ​​with a difference of no more than 0.5 mN / m.

[0101] The method for detecting the amount of fuzz includes: using the company's self-made carbon fiber wear resistance testing device (invention patent CN105445131A) to evaluate the amount of fuzz in the fiber bundle (12K) after sizing, and the judgment criteria are as follows.

[0102] Excellent: The number of hair fibers per unit length of the fiber bundle is less than 2 (inclusive).

[0103] Good: The number of fiber strands per unit length is 3 to 5.

[0104] Middle: The number of filaments per unit length of fiber bundle is 6 to 9.

[0105] Poor: The number of hair fibers per unit length of fiber bundle is 10 or more.

[0106] The method for detecting the interface shear strength includes: using a composite material interface evaluation device (HM410, TOHEISANGYO Co., Ltd., Japan) to evaluate the interface shear strength of the droplet composite material. Randomly take out carbon fiber monofilaments from the carbon fiber bundles of the embodiment and the comparative example, straighten and fix them on a stainless steel template, transfer the molten polyamide 6 resin (grade CM1017, Toray Industries, Ltd.) to the carbon fiber monofilament with a pin to form resin droplets, and program the temperature to 230˚C (5˚C higher than the melting point of PA6) in a tube furnace and keep it warm for 10 minutes to release residual thermal stress, and naturally cool to room temperature. Fix the sample in the interface evaluation device, observe and measure the droplet embedding length through an optical microscope l and fiber diameter d After the solid resin contacts the cutter, the force required to peel the droplet from the fiber is measured and recorded. F max The interfacial shear strength τ of the composite material can be obtained by Calculation shows that the greater the interfacial shear strength, the stronger the bonding between the fiber and the resin.

[0107] Please see the table below for test results.

[0108] Example Average particle size (nm) Surfactant (wt.%) Surface tension (mN / m) Hair volume Interface shear strength (MPa) Example 1 148.9 0.05 29.5 excellent 49.3 Example 2 68.4 0.05 29.2 good 48.1 Example 3 148.9 0.05 31.0 excellent 50.6 Example 4 33.1 0.05 29.9 excellent 45.5 Example 5 148.9 0.05 34.5 good 49.9 Example 6 148.9 0.1 26.4 excellent 46.8 Example 7 148.9 0.5 29.7 excellent 41.1 Example 8 148.9 0.05 29.3 excellent 51.6 Comparative Example 1 68.4 0 44.5 Difference 37.7 Comparative Example 2 148.9 0.2 38.9 middle 32.8 Comparative Example 3 148.9 0.2 40.9 Difference 34.9 From the above table, it can be seen that by adding a very small amount of surfactant, the surface tension of the sizing agent can be reduced to about 30 mN / m. At this time, the sizing agent has excellent wettability to the carbon fiber, resulting in a reduced amount of hair in the carbon fiber bundle after sizing and a high interfacial shear strength. At the same time, it can be seen from Example 7 that by continuing to increase the amount of surfactant added, the surface tension will not be further reduced, and therefore the wettability of the sizing agent to the carbon fiber cannot be further improved.

[0109] From the attached Figure 2 It can be seen that compared with the carbon fiber in Comparative Example 1, Example 1 has a higher surface activity due to the presence of surfactant A1, so the sizing agent fully wets and spreads on the surface of the carbon fiber, and the film is more uniform. In addition, in Comparative Example 2, in order to obtain an acceptable surface tension, the amount of surfactant D1 added is 4 times that of A1, as a result, the bonding between the carbon fiber and the matrix resin after sizing is weakened, and the interfacial shear strength is greatly reduced, which fully proves that other surfactants cannot achieve the effect of the surfactant of the present invention. It can be seen from the data of Comparative Example 3 that when the polyurethane surfactant D2 is selected, due to the lack of organic fluorine, the surface tension of the sizing agent is difficult to drop to below 40 mN / m, and the wettability of the carbon fiber is weakened, so it is easy to produce uneven coverage of the sizing agent, thereby affecting the performance of the composite material.

[0110] In summary, the fluorinated polyurethane surfactant provided by the present invention introduces organic fluorine so that the surfactant has extremely low surface energy, and it can be compounded with aqueous polyurethane to prepare a sizing agent. The fluorinated polyurethane surfactant has a strong affinity with aqueous polyurethane, which is conducive to the development of its surface activity. When the addition amount of the fluorinated polyurethane surfactant is as low as 0.01 wt.%, the surface tension of the sizing agent can be reduced to less than 40 mN / m, and the adhesion between the carbon fiber and the matrix resin after sizing will not be adversely affected. The sizing agent has excellent permeability between carbon fiber bundles, and forms a uniform and smooth film on the surface of the carbon fiber, so that the fiber bundles after sizing have excellent processability, and the adhesion with the matrix resin is strong.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A surfactant, characterized in that Its structural formula is at least one of formula (1) and formula (2): （1） （2）； Among them, R f (CH2) n It is a C3~C12 hydrocarbon group in which at least one hydrogen atom directly connected to the carbon atom is replaced by a fluorine atom, and n represents the number of methylene groups, n=1~2; R1 is an alkylene group directly connected to two isocyanate groups in a diisocyanate molecule; R2 is a hydrogen atom or a C1~C2 hydrocarbon group; (AO) m It is a polyether of C2~C4 alkyleneoxy groups, m represents the number average added mole number of alkyleneoxy groups, and m=4~180.

2. The surfactant according to claim 1, characterized in that The R f (CH2) n is a C3-C12 aliphatic or aromatic hydrocarbon group in which at least one hydrogen atom directly connected to a carbon atom is replaced by a fluorine atom; the diisocyanate comprises at least one of an aromatic diisocyanate, an aromatic aliphatic diisocyanate, an aliphatic diisocyanate, an alicyclic diisocyanate and a cycloaliphatic diisocyanate; the (AO) m AO is at least one of ethyleneoxy, propyleneoxy and butyleneoxy, and m=13-136.

3. The surfactant according to claim 2, characterized in that The R f (CH2) n The invention comprises at least one of features (1) to (5): Feature (1): The aliphatic hydrocarbon group includes 3,3-difluoropropyl, 3,3,3-trifluoropropyl, 4,4,4-trifluoro-2-butenyl, 3,3,4,4,4-pentafluorobutyl, 2,2,3,3,4,4,4-heptafluorobutyl, 5,5,5-trifluoropentyl, 4,4,5,5,5-pentafluoropentyl, 3,3,4,4,5,5,5-heptafluoropentyl, 2,2,3,3,4,4,5,5-octafluoropentyl, 1H,1H-perfluoropentyl, 1H,1H,2H,2H-perfluorohexyl, 1H, 1H-perfluorohexyl, 1H,1H,7H-perfluoroheptyl, 1H,1H-perfluoroheptyl, 1H,1H,2H,2H-perfluorooctyl, 1H,1H,8H-perfluorooctyl, 1H,1H-perfluorooctyl, 1H,1H,2H,2H,3H,3H-perfluorononyl, 1H,1H,9H-perfluorononyl, 1H,1H-perfluorononyl, 1H,1H,2H,2H-perfluorodecyl, 1H,1H-perfluorodecyl, 1H,1H,11H-perfluoroundecyl or 1H,1H-perfluorododecyl; Feature (2): The aromatic hydrocarbon group includes 2-fluorobenzyl, 4-fluorobenzyl, 2-fluoro-4-methylbenzyl, 4-(4-fluorophenyl)benzyl, 2,5-difluorobenzyl, 3,5-difluorobenzyl, 2,6-difluorobenzyl, 3,4,5-trifluorobenzyl, 2,3,4,5,6-pentafluorobenzyl, 3-(trifluoromethyl)-benzyl, 2-(trifluoromethyl)-benzyl, 4-(trifluoromethyl)-benzyl or 2-fluoro-6-methylbenzyl; Feature (3): The R f (CH2) n A C3-C12 aliphatic hydrocarbon group in which at least three hydrogen atoms directly connected to carbon atoms are replaced by fluorine atoms; Feature (4): The R f (CH2) n A C4-C8 aliphatic hydrocarbon group in which at least 5 hydrogen atoms directly connected to carbon atoms are replaced by fluorine atoms; Feature (5): The R f (CH2) n It is at least one of 1H,1H,2H,2H-perfluorohexyl, 1H,1H-perfluorohexyl, 1H,1H,2H,2H-perfluorooctyl and 1H,1H-perfluorooctyl.

4. The surfactant according to claim 2, characterized in that The diisocyanate comprises at least one of features (6) to (11); Feature (6): The aromatic diisocyanate includes at least one of toluene-2,6-diisocyanate, toluene-2,4-diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate and dimethylbiphenyl diisocyanate; Feature (7): The aromatic aliphatic diisocyanate includes at least one of xylylene diisocyanate and tetramethyl metaxylylene diisocyanate; Feature (8): The aliphatic diisocyanate includes at least one of 1,6-hexamethylene diisocyanate and trimethyl-1,6-hexamethylene diisocyanate; Feature (9): The alicyclic diisocyanate includes at least one of isophorone diisocyanate, 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and methylcyclohexyl diisocyanate; Feature (10): The cycloaliphatic diisocyanate includes at least one of cyclohexane dimethylene diisocyanate and norbornane diisocyanate; Feature (11): The diisocyanate is toluene-2,6-diisocyanate or toluene-2,4-diisocyanate.

5. The surfactant according to claim 1, characterized in that The R f (CH2) n It is introduced into the macromolecule of the surfactant by bonding the active hydrogen-containing group directly connected thereto to one isocyanate group of the diisocyanate; Wherein, the active hydrogen-containing group includes a hydroxyl group or an amino group.

6. A method for preparing a surfactant according to any one of claims 1 to 5, characterized in that: It includes: Add a catalyst and a solvent to the diisocyanate, raise the temperature to 40-60° C., add an organic fluoride containing active hydrogen dropwise, raise the temperature to 60-100° C. after the addition is complete, react for 2-12 hours, determine the isocyanate group content by a di-n-butylamine method, and lower the temperature to below 50° C. when the content reaches or falls below a first target value; Subsequently, a monofunctional polyether in which the hydroxyl hydrogen is replaced by a methyl group is added dropwise to the system, and after the addition is completed, the temperature is raised to 70-100° C. and aged for 2-12 hours, and the isocyanate group content is determined by the di-n-butylamine method. When the content reaches or is lower than the second target value, the reaction is terminated, and the target surfactant is obtained after the solvent is removed; Wherein, the structural formula of the diisocyanate is The structural formula of the organic fluoride containing active hydrogen is or The structural formula of the monofunctional polyether in which the hydroxyl hydrogen is replaced by a methyl group is .

7. The method for preparing a surfactant according to claim 6, characterized in that: The preparation method of the surfactant comprises at least one of features (12) to (18): Feature (12): The molar ratio of the diisocyanate to the organic fluoride containing active hydrogen is 1:0.5-1.5; Feature (13): The mass ratio of the diisocyanate, the catalyst and the solvent is 1:(0-0.02):(0-20); Feature (14): The catalyst comprises at least one of a tertiary amine catalyst and an organometallic catalyst; wherein the tertiary amine catalyst comprises at least one of triethylenediamine, bis(dimethylaminoethyl) ether and dimethylethanolamine; and the organometallic catalyst comprises at least one of dibutyltin dilaurate and stannous octoate; Feature (15): The solvent comprises at least one of acetone, 2-butanone, ethyl acetate, toluene, dimethylformamide and methylpyrrolidone; Feature (16): The first target value is 25-75% of the initial molar number of isocyanate groups; Feature (17): The molar ratio of the remaining isocyanate groups in the system to the monofunctional polyether in which the hydroxyl hydrogen is substituted by a methyl group is 1:1; Feature (18): The second target value is 0.

8. A sizing agent, characterized in that The composition comprises a non-volatile component having a concentration of 0.1 to 20 wt.% and a volatile component having a concentration of 80 to 99.9 wt.%; the non-volatile component comprises, in terms of the mass percentage of the sizing agent, 0.001 to 0.5 wt.% of a surfactant and 0.099 to 19.999 wt.% of an aqueous polyurethane; the surfactant is a surfactant according to any one of claims 1 to 5, or is prepared by the preparation method of a surfactant according to any one of claims 6 to 7; The surface tension of the sizing agent is 40-25 mN / m; And / or, the average particle size of the sizing agent is less than 1000 nm.

9. A carbon fiber bundle, characterized in that: It comprises a raw carbon fiber bundle and the sizing agent according to claim 8, wherein the sizing agent is attached to the raw carbon fiber bundle, and the attached amount of the sizing agent is 0.1 to 20 wt.% of the total weight of the sizing agent and the raw carbon fiber bundle.

10. A carbon fiber reinforced resin-based composite material, characterized in that: It comprises the carbon fiber bundle as claimed in claim 9 and a matrix resin.

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