阅读说明：本技术 一种碳纤维原丝用无硅油剂 (Silicone oil-free agent for carbon fiber precursor ) 是由 钱京 张淑斌 顾红星 白向鸽 李国明 于 2019-09-18 设计创作，主要内容包括：本发明公开了一种碳纤维原丝用无硅油剂,包括芳香族酯类化合物、芳香族聚氧乙烯醚、胺类化合物按质量比50-80：10-35：1-5分散在水中形成的水性乳液；芳香族酯类化合物包括苯三甲酸酯、苯二甲酸酯、羟基苯甲酸酯以及乙氧化双酚高级脂肪酸酯中的一种或以上；芳香族聚氧乙烯醚包括烷基酚聚氧乙烯醚、双酚A聚氧乙烯醚中的一种或以上；胺类化合物包括乙氧化月桂酰胺、脂肪族长链季铵盐中的一种或以上；且芳香族酯类化合物在空气气氛下300℃时的质量残存率为80～98％,在油剂不挥发性组分中的质量比为50～80％。其可有效地减少原丝生产过程中的粘辊程度,防止PAN单丝在预氧化过程中粘连并丝,又具有一定的亲水性和耐热性。(The invention discloses a silicone oil-free agent for carbon fiber precursors, which comprises an aromatic ester compound, aromatic polyoxyethylene ether and an amine compound in a mass ratio of 50-80: 10-35: 1-5 aqueous emulsions dispersed in water; the aromatic ester compound comprises one or more of benzene tricarboxylate, phthalate, hydroxybenzoate and ethoxylated bisphenol higher fatty acid ester; the aromatic polyoxyethylene ether comprises one or more of alkylphenol polyoxyethylene and bisphenol A polyoxyethylene; the amine compound comprises one or more of ethoxylated lauramide and aliphatic long-chain quaternary ammonium salt; and the aromatic ester compound has a mass residual rate of 80-98% at 300 ℃ in an air atmosphere, and the mass ratio of the aromatic ester compound to the nonvolatile component of the oil agent is 50-80%. The method can effectively reduce the roller sticking degree in the protofilament production process, prevent PAN monofilaments from being stuck and doubled in the pre-oxidation process, and has certain hydrophilicity and heat resistance.)

1. The silicone-free agent for the carbon fiber precursor is characterized by comprising an aromatic ester compound A, an aromatic polyoxyethylene ether B and an amine compound C in a mass ratio of (50-80): (10-35): (1-5) an aqueous emulsion formed by dispersing in water;

the aromatic ester compound A comprises one or more of benzene tricarbamate, phthalate, hydroxybenzoate and ethoxylated bisphenol A higher fatty acid ester;

the aromatic polyoxyethylene ether B comprises one or more of alkylphenol polyoxyethylene and bisphenol A polyoxyethylene;

the amine compound C comprises one or more of ethoxylated lauramide and aliphatic long-chain quaternary ammonium salt;

the aromatic ester compound A has a mass residual rate of 80-98% at 300 ℃ in an air atmosphere, and the mass ratio of the aromatic ester compound A to the non-volatile components of the oil agent is 50-80%.

2. The silicone-free agent for carbon fiber precursors according to claim 1, wherein the average particle diameter of the aqueous emulsion is 50 to 500nm, and the content of nonvolatile components in the aqueous emulsion is 5 to 50 wt%.

3. The silicone-free agent for carbon fiber strands according to claim 1, wherein the trimellitate ester includes 1,2, 4-benzenetricarboxylate, 1,2, 3-benzenetricarboxylate, and 1,3, 5-benzenetricarboxylate;

wherein the structural formula of the trimellitic ester is as follows:

in the formula 1, R₁、R₂、R₃Respectively is a hydrocarbon group with 7-13 carbon atoms;

the benzene tricarboxylate is prepared by esterification reaction of benzene tricarboxylic acid and aliphatic monohydric alcohol with 7-13 carbon atoms.

4. The silicone-free agent for carbon fiber filaments according to claim 1, wherein the phthalic acid ester includes 1, 2-phthalic acid ester, 1, 3-phthalic acid ester, and 1, 4-phthalic acid ester;

wherein, the structural formula of the 1, 2-phthalic acid ester is as follows:

in the formula 2, R₄、R₅Respectively is a hydrocarbon group with 8-15 carbon atoms;

the phthalic acid ester is prepared from phthalic acid and aliphatic monohydric alcohol with the carbon atom number of 8-15 through esterification reaction.

5. The silicone-free agent for carbon fiber precursor according to claim 1, wherein the hydroxybenzoate comprises 1-hydroxy-4-benzoate, 1-hydroxy-2-benzoate, and 1-hydroxy-3-benzoate;

wherein, the structural formula of the 1-hydroxy-4-benzoate is as follows:

in the formula 3, R₆Is a hydrocarbon group with 10-20 carbon atoms;

the hydroxybenzoate is prepared by esterification reaction of hydroxybenzoic acid and aliphatic monohydric alcohol with 10-20 carbon atoms.

6. The silicone oil-free agent for carbon fiber precursor according to claim 1, wherein the ethoxylated bisphenol A fatty acid ester has the following structural formula:

in the formula 4, R₇、R₈Respectively is a hydrocarbon group with 7-15 carbon atoms; m and n are respectively an integer of 2-4;

the ethoxylated bisphenol A fatty acid ester is prepared by using ethoxylated bisphenol A and aliphatic monobasic acid as raw materials.

7. The silicone oil-free agent for carbon fiber precursors according to claim 1, wherein the alkylphenol ethoxylates have the following structural formula:

in the formula 5, R₉Is an alkyl group having 6 to 12 carbon atoms, and r is an integer of 2 to 20.

8. The silicone oil-free agent for carbon fiber precursor according to claim 1, wherein the bisphenol A polyoxyethylene ether has the following structural formula:

in the formula 6, p and q are integers of 2-20 respectively.

9. The silicone-free agent for carbon fiber precursors according to claim 1, further comprising an auxiliary additive in a mass ratio of 0.1 to 5%, wherein the auxiliary additive is at least one of an antioxidant, a pH adjuster, a defoaming agent, a preservative, and a stabilizer.

10. The silicone oil-free agent for carbon fiber precursors according to claim 1, wherein the mass ratio of the aromatic polyoxyethylene ether B in the nonvolatile components of the oil agent is 10-35%; the mass ratio of the amine compound C in the nonvolatile components of the oil solution is 1-5%.

Technical Field

The invention relates to a silicon-free oil agent, in particular to a silicon-free oil agent for carbon fiber precursors, and belongs to the technical field of textile oil agents.

Background

The carbon fiber has good specific strength and specific elastic modulus, so the carbon fiber is widely used as a reinforcing material in the field of advanced composite materials. The industrial production method of carbon fiber is that Polyacrylonitrile (PAN) fiber bundle is pre-oxidized in oxidizing atmosphere between 200 ℃ and 400 ℃ to obtain non-combustible and non-fusible pre-oxidized fiber, and then carbonized in inert atmosphere such as nitrogen at high temperature of at least 1000 ℃ to obtain carbon fiber.

In the pre-oxidation process, the process temperature exceeds the softening point of the PAN precursor, the PAN precursor can be softened or even melted under the action of heat, adjacent monofilaments can be bonded with each other, and the multi-single-filament fibers are combined together, so that the phenomenon of bonding and doubling is generated. The adhesion and doubling of PAN monofilaments can directly cause the increase of broken filaments, the performance and the grade of fibers are reduced, and severe fibers can even cause the breakage of the filaments, thereby influencing the normal operation of production.

To solve this problem, the industrial solution is to treat the raw filaments with a special oil solution to form a protective film having good heat resistance on the surface layer of the PAN fibers, thereby separating the filaments from each other and preventing them from blocking at high temperature. The oil used is generally a silicone oil, that is, an oil containing a silicone-based substance as a main component.

The silicon oil agent has good film forming property, heat resistance, antistatic property and friction resistance, and can effectively prevent the PAN fiber from being adhered and doubled in the pre-oxidation process in actual use, but the silicon oil agent also has some defects. In the heat treatment process of the fiber, the oil agent attached to the fiber is volatilized and decomposed to cause pollution to equipment, the hydrophobicity is strong, and the uniform dispersibility on the wet fiber obtained after spinning is not good.

Firstly, in the process of manufacturing and pre-oxidizing the raw silk, silicon oil partially falls off from fibers and is attached to a roller, intermolecular or intramolecular crosslinking is generated under the action of heat to form jelly, the smoothness of the surface of the roller is seriously affected after long-term accumulation, and the phenomenon of winding and sticking to the roller is caused, so that the increase of the raw silk or the winding of the silk is caused. Secondly, in the carbonization process at higher temperature, the silicon oil is thermally graded to generate inorganic silicides such as silicon oxide, silicon carbide, silicon nitride and the like. These substances are deposited in large quantities on the inner walls of the retort and in the exhaust channels, and have to be shut down and cleaned frequently. Finally, silicone oil is a main source of carbon fiber ash, and in some fields with strict requirements on the fiber ash, such as the field of carbon/carbon composite materials, the silicon remaining in the carbon fiber can have serious adverse effects on key properties such as strength and ablation resistance of the material, so that the using amount of the silicone oil needs to be strictly limited.

Many solutions have been proposed to solve the above problems of the silicone oils. The basic idea is to reduce the content of silicon-based substances in the oil agent as much as possible until the oil agent does not contain silicon. For example:

patent CN 102965944 (document 1) proposes a PAN protofilament generation technology, in which a protofilament is oiled twice, the first oiling uses polybasic ester as the main component, and the second oiling uses aromatic ester and amino silicone oil as the main components;

patent CN 101326313 (document 2) proposes an oil agent using an ester compound having 3 or more ester groups in the molecule and a silicone oil as essential components;

patent CN 103582730 (document 3) proposes a carbon fiber precursor oil agent containing at least one of a hydroxybenzoate, cyclohexanedicarboxylate ester, and an isophorone diisocyanate fatty alcohol adduct;

patent CN 105442097 (document 4) proposes a silicone-free oil agent containing two specific types of substances;

patent CN 107740206 (document 5) proposes a method for producing a low-ash PAN-based carbon fiber using a highly heat-resistant silicone-free oil composed of a saturated linear monoester, a hindered phenol-based antioxidant and a surfactant.

In documents 1,2 and 3, a silicon-based substance and a non-silicon substance are used as main active ingredients of the oil agent, and the content of the silicone oil in the nonvolatile component varies, but the above problem cannot be solved completely if the silicone oil is contained, and particularly ash content of the fiber. In addition, the two-stage oiling method adopted in document 1 additionally increases the equipment cost compared with one-step oiling. In document 3, the aliphatic ester compound used has insufficient heat resistance, and there is room for improvement in the effect of preventing the blocking of monofilaments. Both of documents 4 and 5 use a silicone oil-free agent, but the effective components in document 4 require several steps to be synthesized, and the production process is complicated; the aliphatic monohydric ester used in document 5 has the same problem as that of document 3, and both of them cannot obtain carbon fibers having excellent performance.

To sum up, in the technology in the field, silicone oil is used to ensure the performance and quality of the fiber, but the problems of roller sticking, deposition in a furnace and fiber ash exist, or a low-silicon or silicone oil-free agent is used, although the problem of silicon oil can be solved to a certain extent, the prevention effect on monofilament adhesion is poor, the performance of the obtained carbon fiber is unsatisfactory, and perfect balance cannot be realized from two aspects. And the active modified groups in the silicone oil are subjected to a crosslinking reaction under the action of heat, so that the main reason for the roller sticking of the silicone oil is that the more the number of the modified groups is, the higher the activity is, and the more obvious the roller sticking is. Inorganic silicide generated by decomposition of silicone oil at high temperature is a main source of deposition in a high-temperature furnace and final carbon fiber ash. The above-mentioned problems inevitably occur as long as the modified silicone oil is used as the main component of the oil agent.

Disclosure of Invention

In order to solve the defects of the prior art, the invention aims to provide the silicon-free oil agent for the carbon fiber precursor, which can realize that the oil agent has good heat resistance, effectively reduce the roller sticking degree in the precursor production process, effectively prevent the PAN monofilament from being adhered and doubled in the pre-oxidation process and simultaneously have certain hydrophilicity.

In order to achieve the above object, the present invention adopts the following technical solutions:

a silicone oil-free agent for carbon fiber precursors comprises an aromatic ester compound A, an aromatic polyoxyethylene ether B and an amine compound C in a mass ratio of (50-80): (10-35): (1-5) an aqueous emulsion formed by dispersing in water;

the aromatic ester compound A comprises one or more of benzene tricarbamate, phthalate, hydroxybenzoate and ethoxylated bisphenol A higher fatty acid ester;

the aromatic polyoxyethylene ether B comprises one or more of alkylphenol polyoxyethylene and bisphenol A polyoxyethylene;

the amine compound C comprises one or more of ethoxylated lauramide and aliphatic long-chain quaternary ammonium salt;

the average particle size of the emulsion is 50-500 nm, the particle size is less than 50nm, the emulsion is difficult to achieve by using a common emulsification method, and the emulsification cost is greatly improved; if the particle size exceeds 500nm, the stability of the emulsion is poor, and the uniform adhesion of the oil agent on the fiber surface is affected. The content of nonvolatile components in the aqueous emulsion is 5-50 wt%; the solid content is lower than 10%, the production and transportation cost of the oil agent is obviously increased, and the production capacity is not improved; if the content exceeds 50%, the stability of the oil emulsion is poor, the long-term storage is not facilitated, demulsification with different degrees is easy to generate in the using process, and the phenomenon of nonuniform oiling is caused.

The trimellitate esters include 1,2, 4-benzenetricarboxylate, 1,2, 3-benzenetricarboxylate and 1,3, 5-benzenetricarboxylate;

wherein the structural formula of the trimellitic ester is as follows:

the benzene tricarbamate in the invention has a structure shown in the formula 1 or similar to the formula 1. Similarly, it means that the relative positions of the three ester groups in the benzene ring may be changed, that is, the benzenetricarboxylate represented by formula 1 is 1,2, 4-benzenetricarboxylate (trimellitate), and in addition, 1,2, 3-benzenetricarboxylate (hemibenzoate) and 1,3, 5-benzenetricarboxylate (trimesate).

In the formula 1, R₁、R₂、R₃Respectively is a hydrocarbon group with 7-13 carbon atoms; r in formula 1₁、R₂、R₃May be the same or different. From the aspect of the difficulty of synthesis and production, the three groups are more convenient to be used as the same group. The carbon number is more than 7, so that the thermal stability of the benzoic acid ester can be ensured, and the effect of preventing the melting and doubling of monofilaments in the pre-oxidation process is ensured; if the number of carbon atoms exceeds 20, the viscosity of the benzoic acid ester is too high, which makes emulsification difficult, and gel and emulsion breaking are likely to occur after emulsification, which is disadvantageous for long-term stable use of the oil agent, and in addition, the phenomenon of non-uniform oiling is likely to occur during use.

The benzene tricarboxylate is prepared by esterification reaction of benzene tricarboxylic acid and aliphatic monohydric alcohol with 7-13 carbon atoms. Thus, R in formula 1₁、R₂、R₃The group is derived from aliphatic monohydric alcohol with 7-13 carbon atoms. The unsaturated group may be saturated or may contain an unsaturated group such as a double bond as long as the number of carbon atoms is 7 to 13, and may be linear or branched. Preferably, a saturated hydrocarbon group having 9 to 12 carbon atoms is used.

The benzoic acid tribasic ester is obtained by condensation esterification reaction of benzene tricarboxylic acid and aliphatic monobasic acid with 7-13 carbon atoms under the condition of no catalyst or existence of known esterification reaction catalyst such as stannate, titanium compound, etc. In order to reduce side reactions, the esterification reaction is preferably carried out in an inert atmosphere, and the reaction temperature is controlled between 180 ℃ and 230 ℃. The molar ratio of the benzene tricarboxylic acid to the aliphatic monohydric alcohol as the raw material in the esterification reaction is 1mol, and the aliphatic alcohol is 1.0 to 1.2 mol. In the case of using a catalyst, after completion of the reaction, the catalyst should be deactivated and then removed with an adsorbent, or the remaining catalyst may adversely affect the properties of the carbon fiber.

The above phthalic acid esters include 1, 2-phthalic acid ester, 1, 3-phthalic acid ester and 1, 4-phthalic acid ester; wherein, the structural formula of the 1, 2-phthalic acid ester is as follows:

the phthalic acid ester in the present invention has a structure represented by the above formula 2 or a structure similar to the formula 2. Here, the term "similar" means that the relative positions of two ester groups in a benzene ring may be changed, that is, the phthalate represented by formula 2 is 1, 2-phthalate (phthalate), and in addition, 1, 3-phthalate (isophthalate) and 1, 4-phthalate (terephthalate).

In the formula 2, R₄、R₅Respectively is a hydrocarbon group with 8-15 carbon atoms; r in formula 2₄、R₅May be the same or different. From the aspect of difficulty of synthesis and production, the two groups are taken as the same group, which is convenient. The carbon number is more than 8, so that the thermal stability of the phthalic acid ester can be ensured, and the effect of preventing the monofilament from melting and doubling in the pre-oxidation process is ensured; if the number of carbon atoms exceeds 15, the phthalate ester tends to have too high a viscosity, which makes emulsification difficult, and tends to cause gelation and demulsification after emulsification, which is disadvantageous for long-term stable use of the oil agent, and tends to cause non-uniform oiling during use.

The phthalic acid ester is prepared from phthalic acid and aliphatic monohydric alcohol with the carbon atom number of 8-15 through esterification reaction. Thus, R in formula 2₄、R₅The group is derived from aliphatic monohydric alcohol with 7-13 carbon atoms. The unsaturated group may be saturated or may contain an unsaturated group such as a double bond as long as the number of carbon atoms is between 8 and 15, and may be linear or branched. Preferably, a saturated hydrocarbon group having 10 to 13 carbon atoms is used.

The synthesis or production of phthalic acid esters is similar to the above-described benzenetricarboxylic acid esters, and therefore, will not be described in detail.

The above-mentioned hydroxybenzoates include 1-hydroxy-4-benzoate, 1-hydroxy-2-benzoate and 1-hydroxy-3-benzoate;

wherein, the structural formula of the 1-hydroxy-4-benzoate is as follows:

the hydroxybenzoate in the present invention has a structure as shown in formula 3 above or similar to formula 3. Similarly, it means that the relative positions of the hydroxyl group and the ester group in the benzene ring may be changed, that is, the hydroxybenzoic acid ester represented by formula 3 is 1-hydroxy-4-benzoate (p-hydroxybenzoate), except for 1-hydroxy-2-benzoate (o-hydroxybenzoate) and 1-hydroxy-3-benzoate (m-hydroxybenzoate).

In the formula 3, R₆Is a hydrocarbon group having 10 to 20 carbon atoms. The carbon number is only more than 10, so that the thermal stability of the hydroxybenzoate can be ensured, and the effect of preventing the melt doubling of monofilaments in the pre-oxidation process is ensured; if the number of carbon atoms exceeds 20, the viscosity of the hydroxybenzoates becomes too high, which makes emulsification difficult, and gels and emulsions are likely to be formed after emulsification, which is disadvantageous for long-term stable use of the oil, and in addition, the phenomenon of non-uniform oiling is likely to occur during use.

The hydroxybenzoate is prepared by esterification reaction of hydroxybenzoic acid and aliphatic monohydric alcohol with 10-20 carbon atoms. Thus, R in formula 3₆The group is derived from aliphatic monohydric alcohol with 10-20 carbon atoms. The unsaturated group may be saturated or may contain an unsaturated group such as a double bond, and may be linear or branched as long as the number of carbon atoms is 10 to 20. In general, the number of carbon atoms is preferably 12 to 18.

The synthesis of hydroxybenzoates is analogous to the benzene tricarboxylates and phthalic acid esters described above. And will not be described in detail herein.

The structural formula of the ethoxylated bisphenol A fatty acid ester is as follows:

in the formula 4, R₇、R₈Respectively is a hydrocarbon group with 7-15 carbon atoms; in the formula 4, R₇、R₈May or may not be the sameAlso, from the viewpoint of the difficulty of synthesis and production, it is preferable that both are the same. As long as the carbon number is more than 7, the good thermal stability of the ethoxylated bisphenol A fatty acid ester can be maintained, and the effect of preventing the adhesion and doubling of monofilaments in the pre-oxidation process is ensured; if the number of carbon atoms is 15 or less, it is ensured that the problems of excessive viscosity, easy gelling, difficult emulsification, and uneven oil application to the filament bundle do not occur. The number of carbon atoms is preferably 11 to 13. The hydrocarbon group is preferably a saturated straight-chain hydrocarbon group.

m and n are required to be between 2 and 4, and the two can be the same or different. If the amount is less than 2, the hydrophilicity of the compound is poor, and emulsification is difficult, and the stability of the resulting emulsion is poor, while if it is more than 4, the heat resistance of the compound cannot be ensured. In addition, in a single molecule, m and n are integers, but even if the proportion of each raw material substance is strictly limited in the production process, the actually obtained ethoxylated bisphenol A fatty acid ester is a mixture of different values of m and n, and in this case, m and n may not be integers (average values of various integer values) as a whole.

The above four substances may be used alone or in combination of two or more. However, the aromatic ester compound A used in the present invention should have a residual mass ratio of 80 to 98% at 300 ℃ in an air atmosphere, whether used alone or in combination.

The mass residual rate means a thermal weight loss curve of a sample obtained by using a thermogravimetric analyzer, and the mass residual rate at 300 ℃ is obtained from the curve. If the mass residual rate is less than 80 percent, the heat resistance is insufficient, a large amount of the PAN precursor is decomposed in the pre-oxidation process, and the PAN precursor cannot be effectively protected to prevent the PAN precursor from adhesion and doubling; the mass residual ratio is more than 98%, and it is practically difficult for the ester compound to appear.

The residual mass ratio of the aromatic ester-based compound a can be varied to some extent by adjusting the number of atoms and the structure of the R group, that is, the hydrocarbon group in each of the above-mentioned compounds. Generally, the larger the number of carbon atoms, the smaller the unsaturated group, and the better the heat resistance of the molecule. However, the number of carbon atoms of each hydrocarbon group should be noted not to exceed the aforementioned range because if the number of carbon atoms is too large, the emulsifying property thereof is affected.

The mass proportion of the aromatic ester compound A in the non-volatile components of the finish (i.e., all the components except water in the finish emulsion) should be between 50 and 80%. If the proportion is less than 50 percent, the heat resistance of the oil agent is insufficient, and the phenomenon of adhesion and doubling among monofilaments cannot be effectively prevented; if the proportion exceeds 80%, it is difficult to obtain a stable emulsion.

The ethoxylated bisphenol A fatty acid ester is prepared by using ethoxylated bisphenol A and aliphatic monobasic acid as raw materials.

The structural formula of the alkylphenol polyoxyethylene is as follows:

in the formula 5, R₉Is an alkyl group having 6 to 12 carbon atoms, and r is an integer of 2 to 20.

The structural formula of the bisphenol A polyoxyethylene ether is as follows:

in the formula 6, p and q are integers of 2-20 respectively.

The aromatic polyoxyethylene ethers in formulas 5 and 6 are mainly used as an emulsifier in the present invention to realize emulsification of the aromatic ester compound a in water. Besides the function of an emulsifier, the oil also has certain lubricating and softening functions. According to the numerical difference of r, p and q, the thermal property, the emulsifying property and the like of the emulsion are obviously different. Generally, the larger the values of r, p and q, the more hydrophilic groups in the molecule, the more hydrophilic the molecule, the better the emulsifying ability, but the heat resistance is also lowered; the smaller the values of r, p and q, the less hydrophilic the resulting emulsion, but the higher the heat resistance.

The aromatic polyoxyethylene ether may be used in a variety of different forms depending on the numerical values of r, p and q, and one of them may be selected, or a variety of forms may be mixed, and it is preferable to use at least two or more forms of the aromatic polyoxyethylene ether, which are different in r, p and q, in view of the overall effect. In the mixing process, the optimal proportioning can be realized by combining the HLB (hydrophilic-lipophilic balance) value of a reference system with the actual test effect.

The mass proportion of the aromatic polyoxyethylene ether B in the nonvolatile components of the oil solution is 10-35%. If the proportion is less than 10 percent, the oil agent is difficult to emulsify, and stable emulsion with small enough grain diameter can not be obtained; if the proportion exceeds 35%, the heat resistance of the entire oil agent is lowered, which is disadvantageous in obtaining a high-performance carbon fiber product.

The amine compound C, such as ethoxylated lauramide, aliphatic long-chain quaternary ammonium salt and the like, plays the roles of an emulsifier, an antistatic agent and an antibacterial agent in the invention. The proportion thereof by mass in all nonvolatile components should be between 1 and 5%. If the ratio is less than 1%, the bundling property of the fibers is deteriorated due to the action of static electricity, which may affect the stability of production and the quality of the product; if it is higher than 5%, the ratio of the other components is required to be adjusted downward, and it is considered to be disadvantageous in view of the whole to achieve the object of the present invention.

In addition to the three substances, on the premise of not influencing the effect of the invention, a small amount of at least one auxiliary additive selected from an antioxidant, a pH regulator, an antifoaming agent, a preservative and a stabilizer can be added into the oil agent according to the requirement, and the mass percentage of the auxiliary additive in the nonvolatile components of the oil emulsion is between 0.1 and 5 percent.

The silicon-free oil agent (aqueous emulsion) of the invention uses water which is preferably deionized water; the emulsification method is not particularly limited, and includes the equipment used and the specific process, and generally known emulsification methods such as a high shear emulsification method, an ultrasonic emulsification method, and a method of emulsification using equipment such as a homogenizer and a high pressure homogenizer may be used. Different emulsification methods are used, the particle size of the obtained emulsion can be different, and the emulsion is properly selected according to the comprehensive consideration of actual conditions, such as production cost, production efficiency, product performance requirements and the like.

The silicon-free oil agent can be diluted to a certain extent as required in actual use. Deionized water is preferably used during dilution, a certain amount of deionized water is slowly added to dilute the oil agent to the required concentration while the oil agent is kept stirred, and then the stirring is continued for half an hour. The diluted oil emulsion can be used for oiling the PAN precursor fiber bundle by an immersion method, a spray method, or the like, and the immersion method is industrially used in many cases in view of equipment cost, uniformity of oiling, and the like.

The amount of finish oil adhering to the PAN fiber, that is, the amount of finish oil, is generally controlled to be 0.5 to 2%. If the oiling amount is too small, the proper effect cannot be achieved, and the stable production and the final performance of the carbon fiber are not good; the oiling amount is more than 2%, so that not only can the waste of the oil agent be caused, the production cost is improved, but also a large amount of oil agent can be decomposed and volatilized in the subsequent heat treatment process, and the deposition amount in the furnace and the treatment amount of waste gas are increased. The amount of oil added to the yarn was measured according to the following method:

a certain amount of protofilament samples are taken and dried for 2 hours at 105 ℃, the mass of the protofilament samples is measured and recorded as W1, the protofilament samples are placed in a Soxhlet extractor, acetone (or organic solvent with proper gas) is added, the temperature is raised to 50 ℃, and the protofilament samples are extracted for 4 hours. The sample was removed, dried at 105 ℃ for 2 hours and the mass was determined and reported as W2. The amount of oil applied was calculated according to the following formula:

the oil amount (wt%) is (W1-W2)/W1.

The number of the filaments of the carbon fiber precursor fiber bundle applicable to the invention is between 1000-; the number of the single filaments is less than 1000, the production efficiency is very low, the fiber cost is high, and after the number of the single filaments exceeds 96000, the oiling uniformity and the uniformity of the subsequent carbon fiber performance are obviously influenced.

The invention has the advantages that:

according to the silicon-free oil agent for the carbon fiber precursor, substances which contain aromatic ring structures with high heat resistance stability and hydrophilic groups such as esters in molecules are selected as main effective components of the oil agent, and the emulsifier selects the surfactant which has better heat resistance and contains aromatic rings in molecules, so that the oil agent has good heat resistance, the PAN monofilaments are effectively prevented from being softened, adhered and doubled in the pre-oxidation process, and meanwhile, the silicone-free oil agent has certain hydrophilicity and can conveniently realize emulsification; has better surface affinity with PAN monofilament, can be uniformly attached to the surface of the fiber, and ensures the quality uniformity of the fiber.

Compared with the traditional silicon oil agent, the silicon-free oil agent can effectively reduce the roller sticking phenomenon in the protofilament generation process, can effectively prevent the adhesion and doubling of filaments in the pre-oxidation process, has small deposition amount in the carbonization process, and can obtain carbon fibers with low ash content and excellent mechanical property; the raw materials are easy to obtain, the synthesis steps are simple and easy to operate, the modification requirement on the existing equipment is low, the preparation method can be properly adjusted according to actual use, and the preparation method comprises the steps of preparing the components and the proportion of the oil agent, the specific type of the aromatic ester compound, the heat resistance of the aromatic ester compound, the specific type of the aromatic polyoxyethylene ether, the solid content of the emulsion, the particle size of the emulsion and the like, and has strong practicability and wide applicability.

Detailed Description

The present invention will be described in detail with reference to the following embodiments.

Various evaluation and measurement methods in the present invention are as follows:

heat-resistant residual ratio: the temperature was raised to 400 ℃ at a temperature rise rate of 10 ℃/min in an air atmosphere using a thermogravimetric analyzer (NETZSCH TG 209F3, germany scale), and the heat-resistant residual rate at 300 ℃ was obtained from the obtained thermogravimetric curve.

Emulsion particle size: measured using a laser particle sizer (malvern, Mastersizer 2000, uk).

Carbon fiber ash: the method is carried out according to the national standard GB/T1429-2009 method for measuring the ash content of the carbon material.

Roller sticking degree in the protofilament production process: one month of continuous production, the number of times the roll surface was cleaned during the period was counted and evaluated according to the following criteria: a is 2 times or less, B is 2-4 times, and C is 5 times or more.

Adhesion and doubling in the pre-oxidation process: the pre-oxidized fiber bundle was cut to a length of 3mm, dispersed in acetone, stirred for 10min, dispersed on filter paper, and the number of doubling between monofilaments was counted under a magnifying glass. The following criteria were used: the number of A is less than 5, the number of B is 5-10, and the number of C is more than 10.

Carbon fiber tensile strength: according to the national standard GB/T26749-2011 determination of tensile property of carbon fiber impregnated yarn.

The production process of the protofilament specifically comprises the following steps: according to the components and mass ratio of the oil agent shown in the table 1, the aromatic ester compound A, the aromatic polyoxyethylene ether B and the amine compound C are mixed and stirred uniformly, deionized water is slowly added while stirring is kept, and emulsification is carried out by using a homogenizer to obtain an emulsion with the solid content of 30 wt%. The particle size of the emulsion was measured. Diluting the emulsion to 2% with water, and adding into an upper oil tank with circulation function for use.

Dissolving PAN copolymer obtained by copolymerizing acrylonitrile and methacrylic acid in dimethyl sulfoxide to prepare spinning solution with the concentration of 21%, and spraying the spinning solution into a coagulation bath consisting of dimethyl sulfoxide water solution with the temperature of 60 ℃ and the concentration of 65% through a spinneret plate with the pore diameter of 60 mu m and the pore number of 12000 to coagulate into filaments. The fiber bundle was drawn while washing off the solvent in a rinsing bath at a draw ratio of 3 to obtain a water-swollen fiber bundle.

And guiding the fiber bundle in the water swelling state into an oil feeding tank for oiling treatment. Then, the resultant was dried and densified by a hot roll having a surface temperature of 150 ℃ and then drawn 5 times in water vapor having a pressure of 0.5MPa to obtain a carbon fiber precursor fiber bundle having a single yarn number of 12000 and a single yarn fineness of 1.1 dtex.

The oil solutions of examples 1 to 7 and comparative examples 1 to 3 in table 1 were used to evaluate the degree of sticking in the course of production of a raw yarn.

The pre-oxidation process specifically comprises the following steps: the obtained precursor fiber bundle is pre-oxidized for 45 minutes in a pre-oxidation furnace with temperature gradient zones at 220-280 ℃ to obtain pre-oxidized fiber. The pre-oxidation process was used to evaluate the degree of blocking and doubling of the strand.

And (3) carbonizing the pre-oxidized fiber for 3 minutes in a carbonization furnace with temperature gradient subareas at 400-1400 ℃ in a nitrogen atmosphere to obtain the carbonized fiber. The above procedure was used to determine the ash content of the carbon fiber tow and the tensile strength of the carbon fibers.