A low-foaming oil agent for PAN-based carbon fiber production and a preparation method thereof

Abstract

This invention proposes a low-foaming oiling agent for the production of PAN-based carbon fibers, comprising, by weight, the following components: 30-60 parts of a side-chain amino-modified polysiloxane of general formula I; 20-40 parts of a quaternary ammonium-modified polyether polysiloxane of general formula II; 10-40 parts of a surfactant; and 1-10 parts of a polyol. In general formula I, x is an integer from 10 to 100, y is an integer from 2 to 10, and R is selected from at least one of -C3H6NH2, -C3H6NHC2H4NH2, and -C3H6NC2H6. In general formula II, p is an integer from 2 to 10, q is an integer from 10 to 100, m is an integer from 2 to 10, n is an integer from 2 to 10, and Z... ‑ This invention relates to anionic groups that make the molecule represented by general formula II charge-neutral. The invention also proposes a method for preparing a low-foaming oiling agent for the production of PAN-based carbon fibers. This low-foaming oiling agent not only effectively reduces bubbles generated during use, but also possesses excellent heat resistance, antistatic properties, smoothness, and emulsion stability.

Description

Technical Field

[0001] This invention relates to a low-foaming oiling agent for the production of PAN-based carbon fibers and its preparation method. Background Technology

[0002] Carbon fiber is a brittle material, and this characteristic limits the improvement of its tensile strength. Among such defects, surface defects account for about 90% and are the source of fracture. Moreover, for defects of the same size, surface defects have a greater impact on tensile strength than internal defects.

[0003] Carbon fiber oil is an essential additive in carbon fiber manufacturing and the most effective technology for suppressing the formation of surface defects in carbon fibers. Its main function is to form a uniformly thick film on the fiber surface, preventing surface defects caused by fiber bundle adhesion and tangling during spinning. It can also greatly reduce friction and wear between the fiber bundle and the roller. During pre-oxidation and low-temperature carbonization, it can also prevent thermal adhesion or tangling of the fiber surface due to localized overheating or tar generation, protecting the fiber surface from damage.

[0004] Oils are generally formulated into aqueous solutions for use. During preparation and use, they are prone to generating excessive foam. Excessive foam can overflow the oil tank, leading to waste, environmental pollution, and in severe cases, potential safety accidents. Furthermore, it can affect the spinning process, reducing the oil application rate and hindering the uniform and rapid formation of the oil film on the fiber surface, causing surface defects and ultimately reducing the strength modulus of the produced carbon fibers. Currently, the most common method to eliminate foam is to add suitable defoamers, with organosilicon compounds being the most frequently used. However, these defoamers have poor dispersibility and compatibility in aqueous systems, affecting defoaming performance and durability. They can also negatively impact the stability of the emulsion, causing surface defects. Summary of the Invention

[0005] Based on the above, the purpose of this invention is to solve the problem that existing PAN-based carbon fiber oiling agents easily generate excessive foam during use, causing VOC pollution in the environment, affecting the spinning process, reducing the oiling rate, and resulting in a decrease in the strength modulus of the produced carbon fibers.

[0006] Therefore, the present invention provides a low-foaming oiling agent for the production of PAN-based carbon fiber and its preparation method. This oiling agent not only effectively reduces the bubbles generated during use, but also has excellent heat resistance, antistatic properties, smoothness and emulsion stability. The polyacrylonitrile-based carbon fiber produced using this oiling agent has excellent main mechanical properties such as strength and modulus, which can well meet the needs of polyacrylonitrile-based carbon fiber production.

[0007] In a first aspect, the present invention provides a low-foaming oiling agent for the production of PAN-based carbon fiber, comprising, by weight, the following components: 30-60 parts of side-chain amino-modified polysiloxane of general formula I; 20-40 parts of quaternary ammonium-modified polyether polysiloxane of general formula II; 10-40 parts of surfactant; and 1-10 parts of polyol.

[0008]

[0009] In general formula I, x is an integer from 10 to 100, preferably an integer from 80 to 100, y is an integer from 2 to 10, and R is selected from at least one of C3H6NH2, C3H6NHC2H4NH2, and C3H6NC2H6;

[0010]

[0011] In general formula II, p is an integer from 2 to 10, q is an integer from 10 to 100, preferably an integer from 80 to 100, m is an integer from 2 to 10, n is an integer from 2 to 10, and Z - It is an anionic group that makes the molecule represented by general formula II charge-neutral as a whole.

[0012] The low-foaming oiling agent for the production of PAN-based carbon fiber provided by this invention uses quaternary ammonium modified polyether polysiloxane as shown in general formula II. Compared with the existing combination of ordinary polyether modified polysiloxane and quaternary ammonium salt antistatic agent, the oiling agent of this invention has low foaming and good mechanical properties of carbon fiber. Furthermore, the introduction of polyols into the formulation further improves the low-foaming performance of the oiling agent.

[0013] As a specific embodiment of the present invention, preferably, the Z - Selected from halide ions, NO3 - CH3COO - and (SO4) 1 / 2 - .

[0014] In a specific embodiment of the present invention, preferably, the surfactant is a composite surfactant comprising polyoxyethylene polyol ester and polyglycerol fatty acid ester.

[0015] As a specific embodiment of the present invention, preferably, the polyoxyethylene polyol ester is selected from at least one of polyoxyethylene polyol esters with an HLB value of 9-16, preferably Tween-81 or Tween-40.

[0016] As a specific embodiment of the present invention, preferably, the polyglycerol fatty acid ester is selected from at least one of polyglycerol fatty acid esters with an HLB value of 2-8, and is preferably diglycerol oleate or triglycerol monooleate.

[0017] As a specific embodiment of the present invention, preferably, the molar ratio of the polyoxyethylene polyol ester to the polyglycerol fatty acid ester is 0.1:1-10:1, more preferably 0.1:1-1:1.

[0018] As a specific embodiment of the present invention, preferably, the polyol is selected from at least one of polyfatty alcohols having 3-6 carbon atoms and 3-6 hydroxyl groups, and more preferably, the polyol is selected from at least one of glycerol, trimethylolpropane, pentaerythritol, mannitol and sorbitol.

[0019] Secondly, the present invention provides a method for preparing the above-mentioned low-foaming oil agent for the production of PAN-based carbon fiber, comprising the following steps:

[0020] (1) The composite surfactant is mixed with side-chain amino-modified polysiloxane and quaternary ammonium-modified polyether polysiloxane to obtain mixture A;

[0021] (2) Polyol and water are mixed to obtain mixture B;

[0022] (3) Mix mixture B into mixture A.

[0023] The above preparation method uses both composite surfactants and polyols, which can improve the stability of the oil formulation and effectively suppress the generation of bubbles during use.

[0024] As a specific embodiment of the present invention, preferably, in step (3), the temperature of the mixing is 40-60°C; and / or the mixing process is carried out under stirring and / or shearing conditions, more preferably the stirring rate is 50-500 r / min, the stirring time is 2-5 h, and / or the shearing rate is 1000-20000 r / min, the shearing time is 1-4 h.

[0025] Specifically, the above emulsification process can further improve the stability of the oil formulation and effectively suppress the generation of bubbles during use.

[0026] In the above specific implementation method, based on the simultaneous use of composite surfactants and polyols, the use of emulsification process can further improve the stability of the oil formulation and effectively suppress the generation of bubbles during use.

[0027] In a specific embodiment of the present invention, preferably, the composite surfactant, the side-chain amino-modified polysiloxane, the quaternary ammonium-modified polyether polysiloxane, and the polyol are the active ingredients, and the active ingredients account for 10-30% of the total weight of the active ingredients and water.

[0028] Those skilled in the art can reasonably select the specific application method of the above-mentioned oil based on existing technology. For example, when used in the production of PAN-based carbon fiber, it needs to be diluted with water to the required concentration, generally 1-3 wt%, and a two-stage oiling process is adopted.

[0029] The specific oiling process and carbon fiber production and evaluation methods are as follows: Polyacrylonitrile precursor fibers from water washing enter the first oiling stage. This first oiling stage uses a low-foaming oiling agent with a concentration of 1.5 wt% at room temperature. Excess oiling agent is squeezed out by extrusion rollers and then enters the first drying and densification stage at 75°C for 40 seconds. A second oiling stage is then performed, also using the same low-foaming oiling agent with a concentration of 3 wt% at room temperature. The precursor fibers leaving the second oiling stage are then extruded again and enter the second drying and densification stage at 120°C for 40 seconds. The resulting precursor fibers are then steam-drawn at a pressure of 0.2 MPa and a draw ratio of 2. The resulting precursor fibers are then steam-heat-set and finally wound up to obtain high-performance polyacrylonitrile precursor fibers. Polyacrylonitrile precursor fibers were heat-stabilized in an air-atmosphere furnace at temperatures ranging from 180°C to 280°C (180°C, 220°C, 235°C, 255°C, and 275°C), with a total heating time of 60 min and a total draw of 2%. The resulting heat-stabilized fibers were then subjected to low-temperature and high-temperature carbonization in nitrogen atmosphere. The low-temperature carbonization was carried out at 300–700°C for 4 min with a draw of 3%; the high-temperature carbonization was carried out at 1000–1500°C for 2 min with a draw of -3%, yielding polyacrylonitrile-based carbon fibers.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) One of the key technologies of this invention is the selection of low-foaming oil formulation. The combination of side-chain amino-modified polysiloxane and quaternary ammonium-modified polyether polysiloxane can effectively improve the emulsification and antistatic properties of the oil while ensuring its smoothness, thereby improving the overall performance of the oil.

[0032] (2) The present invention uses composite surfactant, polyol and emulsification process to further improve the stability of oil formulation and effectively suppress the generation of bubbles during use. The main mechanical properties such as strength and modulus of polyacrylonitrile-based carbon fiber produced by using this low foaming oil are greatly improved. Detailed Implementation

[0033] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0034] Example 1

[0035] (1) 40 parts by weight of side-chain amino-modified polysiloxane 1 (in general formula I, x = 80, y = 5, R = -C3H6NHC2H4NH2); quaternary ammonium-modified polyether polysiloxane 1 (in general formula II, p = 5, q = 80, m = 4, n = 6, Z - =Cl - ), 30 parts by weight; POE(5) sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 13 parts by weight; diglyceride oleate, HLB = 5.5, 13 parts by weight; mix thoroughly at 50°C to obtain mixture A1.

[0036] (2) Mix 4 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B1.

[0037] (3) At 50℃, mixture B1 was slowly added to mixture A1 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 182 days. The foaming height of the oil agent was 50 mm, and the defoaming time was 10.3 s.

[0038] Example 2

[0039] (1) 40 parts by weight of side-chain amino-modified polysiloxane 2 (in general formula I, x = 100, y = 2, R = -C3H6NH2); quaternary ammonium-modified polyether polysiloxane 1 (in general formula II, p = 5, q = 80, m = 4, n = 6, Z - =Cl - ), 30 parts by weight; POE(5) sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 13 parts by weight; diglyceride oleate, HLB = 5.5, 13 parts by weight; mix thoroughly at 50°C to obtain mixture A2.

[0040] (2) Mix 4 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B1.

[0041] (3) At 50℃, mixture B1 was slowly added to mixture A2 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 178 days. The foaming height of the oil agent was 53 mm, and the defoaming time was 10.6 s.

[0042] Example 3

[0043] (1) 40 parts by weight of side-chain amino-modified polysiloxane 1 (in general formula I, x = 80, y = 5, R = -C3H6NHC2H4NH2); quaternary ammonium-modified polyether polysiloxane 2 (in general formula II, p = 2, q = 100, m = 2, n = 2, Z - =NO3 - ), 30 parts by weight; POE(5) sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 13 parts by weight; diglyceride oleate, HLB = 5.5, 13 parts by weight; mix thoroughly at 50°C to obtain mixture A3.

[0044] (2) Mix 4 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B1.

[0045] (3) At 50℃, mixture B1 was slowly added to mixture A3 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 181 days. The foaming height of the oil agent was 52 mm, and the defoaming time was 10.5 s.

[0046] Example 4

[0047] (1) 40 parts by weight of side-chain amino-modified polysiloxane 1 (in general formula I, x = 80, y = 5, R = -C3H6NHC2H4NH2); quaternary ammonium-modified polyether polysiloxane 1 (in general formula II, p = 5, q = 80, m = 4, n = 6, Z - =Cl - ), 30 parts by weight; POE(5) sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 13 parts by weight; diglyceride oleate, HLB = 5.5, 13 parts by weight; mix thoroughly at 50°C to obtain mixture A1.

[0048] (2) Mix 4 parts by weight of trimethylolpropane and 400 parts by weight of deionized water thoroughly to obtain mixture B2.

[0049] (3) At 50℃, mixture B2 was slowly added to mixture A1 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 176 days. The foaming height of the oil agent was 53 mm, and the defoaming time was 10.8 s.

[0050] Example 5

[0051] (1) 40 parts by weight of side-chain amino-modified polysiloxane 1 (in general formula I, x = 80, y = 5, R = -C3H6NHC2H4NH2); quaternary ammonium-modified polyether polysiloxane 1 (in general formula II, p = 5, q = 80, m = 4, n = 6, Z - =Cl - ), 30 parts by weight; polyoxyethylene sorbitan monopalmitate (abbreviated as: Tween-40), HLB value = 15.6, 13 parts by weight; triglyceride monooleate, HLB = 7.0, 13 parts by weight; mix thoroughly at 50°C to obtain mixture A5.

[0052] (2) Mix 4 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B1.

[0053] (3) At 50℃, mixture B1 was slowly added to mixture A5 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 173 days. The foaming height of the oil agent was 55 mm, and the defoaming time was 11.1 s.

[0054] Example 6

[0055] (1) 30 parts by weight of side-chain amino-modified polysiloxane 1 (in general formula I, x = 80, y = 5, R = -C3H6NHC2H4NH2); quaternary ammonium-modified polyether polysiloxane 1 (in general formula II, p = 5, q = 80, m = 4, n = 6, Z - =Cl - ), 40 parts by weight; POE(5) sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 10 parts by weight; diglyceride oleate, HLB = 5.5, 10 parts by weight; mix thoroughly at 50°C to obtain mixture A6.

[0056] (2) Mix 10 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B3.

[0057] (3) At 50℃, mixture B3 was slowly added to mixture A6 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 171 days. The foaming height of the oil agent was 48 mm, and the defoaming time was 10.1 s.

[0058] Example 7

[0059] (1) 40 parts by weight of side-chain amino-modified polysiloxane 1 (in general formula I, x = 80, y = 5, R = -C3H6NHC2H4NH2); quaternary ammonium-modified polyether polysiloxane 1 (in general formula II, p = 5, q = 80, m = 4, n = 6, Z - =Cl - ), 30 parts by weight; POE(5) dehydrated sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 2 parts by weight; diglyceride oleate, HLB = 5.5, 20 parts by weight; mix thoroughly at 50°C to obtain mixture A7.

[0060] (2) Mix 8 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B4.

[0061] (3) At 50℃, mixture B4 was slowly added to mixture A7 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 174 days. The foaming height of the oil agent was 56 mm, and the defoaming time was 11.2 s.

[0062] Example 8

[0063] (1) 60 parts by weight of side-chain amino-modified polysiloxane 1 (in general formula I, x = 80, y = 5, R = -C3H6NHC2H4NH2); quaternary ammonium-modified polyether polysiloxane 1 (in general formula II, p = 5, q = 80, m = 4, n = 6, Z - =Cl - ), 20 parts by weight; POE(5) sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 17 parts by weight; diglyceride oleate, HLB = 5.5, 2 parts by weight; mix thoroughly at 50°C to obtain mixture A8.

[0064] (2) Mix 1 part by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B5.

[0065] (3) At 50℃, mixture B5 was slowly added to mixture A8 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 175 days. The foaming height of the oil agent was 54 mm, and the defoaming time was 10.9 s.

[0066] Example 9

[0067] (1) 40 parts by weight of side-chain amino-modified polysiloxane 3 (in general formula I, x = 80, y = 5, R = -C3H6NC2H6); quaternary ammonium-modified polyether polysiloxane 1 (in general formula II, p = 5, q = 80, m = 4, n = 6, Z - =Cl - ), 30 parts by weight; POE(5) sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 13 parts by weight; diglyceride oleate, HLB = 5.5, 13 parts by weight; mix thoroughly at 50°C to obtain mixture A4.

[0068] (2) Mix 4 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B1.

[0069] (3) At 50℃, mixture B1 was slowly added to mixture A4 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 177 days. The foaming height of the oil agent was 51 mm, and the defoaming time was 10.7 s.

[0070] Comparative Example 1

[0071] (1) 40 parts by weight of side-chain amino-modified polysiloxane 1 (in general formula I, x = 80, y = 5, R = -C3H6NHC2H4NH2); 15 parts by weight of side-chain polyether-modified polysiloxane (Shin-Etsu Organosilicon: KF-6013); 15 parts by weight of dodecyltrimethylammonium bromide; 13 parts by weight of POE(5) sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0; and 13 parts by weight of diglyceride oleate, HLB = 5.5, were thoroughly mixed to obtain mixture A9.

[0072] (2) Mix 4 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B1.

[0073] (3) At 50℃, mixture B1 is slowly added to mixture A9 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing is performed for 3 hours at a shear rate of 5000 r / min to mix the two evenly and obtain an oil agent with an effective concentration of 20 w%. The oil agent has good stability, and the time required for standing and stratification is 151 days. The foaming height of the oil agent is 90 mm and the defoaming time is 23.1 s.

[0074] Comparative Example 2

[0075] 40 parts by weight of side-chain amino-modified polysiloxane 1 (in general formula I, x = 80, y = 5, R = -C3H6NHC2H4NH2); quaternary ammonium-modified polyether polysiloxane 1 (p = 5, q = 80, m = 4, n = 6, Z... - =Cl - ), 30 parts by weight; POE(5) dehydrated sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 15 parts by weight; diglyceride oleate, HLB = 5.5, 15 parts by weight; at 50℃, the mixture was thoroughly stirred and mixed, and 400 parts by weight of deionized water was slowly added. The mixture was stirred for 3 hours at a stirring rate of 300 r / min and sheared for 3 hours at a shear rate of 5000 r / min. The two were then mixed evenly to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 37 days. The foaming height of the oil agent was 86 mm, and the defoaming time was 19.2 s.

[0076] Comparative Example 3

[0077] (1) 40 parts by weight of side-chain amino-modified polysiloxane 1 (x = 80, y = 5, R = -C3H6NHC2H4NH2), and quaternary ammonium-modified polyether polysiloxane 1 (p = 5, q = 80, m = 4, n = 6, Z) were added. - =Cl - ), 30 parts by weight, POE(5) sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0, 13 parts by weight; diglyceride oleate, HLB = 5.5, 13 parts by weight; mix thoroughly at 50°C to obtain mixture A10.

[0078] (2) Mix 4 parts by weight of 1,2-propanediol and 400 parts by weight of deionized water thoroughly to obtain mixture B6.

[0079] (3) At 50℃, mixture B6 was slowly added to mixture A10 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 148 days. The foaming height of the oil agent was 94 mm, and the defoaming time was 25.3 s.

[0080] Comparative Example 4

[0081] (1) 40 parts by weight of side-chain amino-modified polysiloxane 1 (x = 80, y = 5, R = -C3H6NHC2H4NH2), 30 parts by weight of side-chain polyether-modified polysiloxane (Shin-Etsu silicone: KF-6013), 13 parts by weight of POE(5) dehydrated sorbitan monooleate (abbreviated as: Tween-81), HLB value = 10.0; 13 parts by weight of diglycerol oleate, HLB = 5.5; and the mixture was stirred thoroughly at 50°C to obtain mixture A11.

[0082] (2) Mix 4 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B1.

[0083] (3) At 50℃, mixture B1 was slowly added to mixture A11 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 156 days. The foaming height of the oil agent was 103 mm, and the defoaming time was 27.8 s.

[0084] Comparative Example 5

[0085] (1) 40 parts by weight of side-chain amino-modified polysiloxane 1 (x = 80, y = 5, R = -C3H6NHC2H4NH2), and quaternary ammonium-modified polyether polysiloxane 1 (p = 5, q = 80, m = 4, n = 6, Z) were added. - =Cl - ), 30 parts by weight of polyoxyethylene sorbitan laurate (abbreviated as: Tween-20), HLB value = 16.5, 13 parts by weight; hexaglycerol monooleate, HLB = 9.5, 13 parts by weight; and the mixture was thoroughly stirred at 50°C to obtain mixture A12.

[0086] (2) Mix 4 parts by weight of glycerol and 400 parts by weight of deionized water thoroughly to obtain mixture B1.

[0087] (3) At 50℃, mixture B6 was slowly added to mixture A10 and stirred for 3 hours at a stirring rate of 300 r / min. Shearing was performed for 3 hours at a shear rate of 5000 r / min to obtain an oil agent with an effective concentration of 20 w%. The oil agent had good stability, and the time required for standing and stratification was 28 days. The foaming height of the oil agent was 91 mm, and the defoaming time was 20.7 s.

[0088] Test Example 1

[0089] The formulations of oils from Examples 1-8 and Comparative Examples 1-5 were prepared with deionized water to a 2w% emulsion concentration for fiber oiling evaluation.

[0090] The specific evaluation method is as follows: The polyacrylonitrile precursor fiber from water washing enters the first oiling stage. The first oiling stage uses the formulations of Examples 1-8 and Comparative Examples 1-5, respectively. The oil concentration of the first oiling stage is 1.5 wt%, and the temperature is room temperature. After the excess oil is squeezed by the extrusion roller, it enters the first drying and densification stage at a temperature of 75°C for 40 seconds. Then, the second oiling stage is performed. The same low-foaming oiling agent is used for the second oiling stage. The oil concentration of the second oiling stage is 3 wt%, and the temperature is room temperature. After leaving the second oiling stage, the precursor fiber is extruded again and enters the second drying and densification stage at a temperature of 120°C for 40 seconds. The obtained precursor fiber is steam drawn at a pressure of 0.2 MPa and a draw ratio of 2. The obtained precursor fiber is then steam heat-set and finally wound up to obtain high-performance polyacrylonitrile precursor fiber. Polyacrylonitrile precursor fibers were heat-stabilized in an air-atmosphere furnace at temperatures ranging from 180°C to 280°C (180°C, 220°C, 235°C, 255°C, and 275°C), with a total heating time of 60 min and a total draw of 2%. The resulting heat-stabilized fibers were then subjected to low-temperature and high-temperature carbonization in nitrogen atmosphere. The low-temperature carbonization was carried out at 300–700°C for 4 min with a draw of 3%; the high-temperature carbonization was carried out at 1000–1500°C for 2 min with a draw of -3%, yielding polyacrylonitrile-based carbon fibers.

[0091] The mechanical properties of carbon fiber were tested according to the national standard GB-T3362-2005.

[0092] The stability of oil emulsions was determined by static stability testing at 25°C: a 20 wt% oil emulsion was stirred for 1 hour to ensure homogeneity, then allowed to stand for a period of time, during which the emulsion required to separate into layers was observed. The longer the time required for separation, the more stable the emulsion.

[0093] The foaming power of the oil was determined according to GB / T 13173.6-91.

[0094] The mechanical properties of carbon fiber were measured according to the national standard GB-T3362-2005.

[0095] For details on the synthesis method of quaternary ammonium modified polyether polysiloxane, please refer to the literature: Synthesis and application of quaternized ammonium modified polyether polysiloxane, Dyeing and Printing Auxiliaries, 2015(6), 32, 44-46.

[0096] The test results are as follows:

[0097] The fibers obtained in Example 1 were smooth, soft, and free of fuzz and adhesion, with a carbon fiber strength of 18.12 cN / dtex and a modulus of 1255.38 cN / dtex; the fibers obtained in Example 2 were smooth, soft, and free of fuzz and adhesion, with a carbon fiber strength of 17.89 cN / dtex and a modulus of 1248.64 cN / dtex; the fibers obtained in Example 3 were smooth, soft, and free of fuzz and adhesion, with a carbon fiber strength of 18.06 cN / dtex and a modulus of 1251.27 cN / dtex; the fibers obtained in Example 4 were smooth, soft, and free of fuzz and adhesion, with a carbon fiber strength of... The fibers obtained in Example 5 were smooth, soft, lint-free, and non-adhesive, with a carbon fiber strength of 17.81 cN / dtex and a modulus of 1247.83 cN / dtex. The fibers obtained in Example 6 were smooth, soft, lint-free, and non-adhesive, with a carbon fiber strength of 17.94 cN / dtex and a modulus of 1250.94 cN / dtex. The fibers obtained in Example 7 were smooth, soft, lint-free, and non-adhesive, with a carbon fiber strength of 17.69 cN / dtex and a modulus of 1246.65 cN / dtex. The fibers obtained in Example 8 were smooth, soft, and free of fuzz and adhesion, with a carbon fiber strength of 17.85 cN / dtex and a modulus of 1249.54 cN / dtex. The fibers obtained in Example 9 were smooth, soft, and free of fuzz and adhesion, with a carbon fiber strength of 18.03 cN / dtex and a modulus of 1248.91 cN / dtex. The fibers obtained in Comparative Example 1 were smooth, soft, and free of fuzz and adhesion, with a carbon fiber strength of 15.87 cN / dtex and a modulus of 1214.81 cN / dtex. The fibers obtained in Comparative Example 2 exhibited fuzz and adhesion, with a carbon fiber strength of... Comparative Example 3: Fibers obtained in Comparative Example 3 were smooth, soft, and free of fuzz and adhesion, with a carbon fiber strength of 15.63 cN / dtex and a modulus of 1212.35 cN / dtex; Comparative Example 4: Fibers obtained in Comparative Example 5 were smooth, soft, and free of fuzz and adhesion, with a carbon fiber strength of 15.37 cN / dtex and a modulus of 1210.46 cN / dtex; Comparative Example 5: Fibers obtained in Comparative Example 5 had fuzz and adhesion, with a carbon fiber strength of 15.58 cN / dtex and a modulus of 1210.77 cN / dtex.

[0098] For ease of statistical analysis, the formulations and test results of each embodiment or comparative example are listed in Table 1 and Table 2, respectively.

[0099] Table 1

[0100]

[0101]

[0102] Table 2

[0103]

[0104]

[0105] Compared with Example 1, which used quaternary ammonium modified polyether polysiloxane, Comparative Example 1 used a combination of ordinary polyether modified polysiloxane and quaternary ammonium salt antistatic agent, resulting in more foam and poorer mechanical properties of carbon fibers. Comparative Example 2 did not add polyols to the oil, resulting in significantly more foam and even worse mechanical properties of carbon fibers. Comparative Example 3 used 1,2-propanediol, which was less effective than glycerol, resulting in significantly more foam and even worse mechanical properties of carbon fibers. Comparative Example 4 did not use quaternary ammonium salt antistatic agent, resulting in even worse effect and more foam. Comparative Example 5 used polyoxyethylene polyol ester and polyglycerol fatty acid ester with HLB values ​​outside the range, resulting in a significant decrease in oil stability, more foam, and lower strength and modulus of carbon fibers.

[0106] As can be seen from Examples 1-9 and Comparative Examples 1-5 above, one of the key technologies of this invention is the selection of the low-foaming oil agent formulation. Using side-chain amino-modified polysiloxanes and quaternary ammonium-modified polyether polysiloxanes can effectively improve the emulsifying and antistatic properties of the oil agent while ensuring its smoothness. Furthermore, they can mutually promote each other, forming a certain degree of cross-linking to enhance the heat resistance of the oil agent. Simultaneously, the use of composite surfactants, polyols, and emulsification processes can further improve the stability of the oil agent formulation and effectively suppress the generation of bubbles during use. The strength, modulus, and other main mechanical properties of polyacrylonitrile-based carbon fibers produced using this low-foaming oil agent are significantly improved.

[0107] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88… and 69-71 and 70-71, etc. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0108] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A low-foaming oiling agent for the production of PAN-based carbon fiber, comprising, by weight, the following components: 30-60 parts of side-chain amino-modified polysiloxane of general formula I; 20-40 parts of quaternary ammonium-modified polyether polysiloxane of general formula II; 10-40 parts of surfactant; and 1-10 parts of polyol. General Formula I In general formula I, x is an integer from 10 to 100, y is an integer from 2 to 10, and R is selected from at least one of -C3H6NH2, -C3H6NHC2H4NH2, and -C3H6NC2H6; Formula II In general formula II, p is an integer from 2 to 10, q is an integer from 10 to 100, m is an integer from 2 to 10, n is an integer from 2 to 10, and Z... - These are anionic groups that make the molecule represented by general formula II charge-neutral as a whole; The polyol is selected from at least one of polyfatty alcohols having 3-6 carbon atoms and 3-6 hydroxyl groups.

2. The low-foaming oil agent according to claim 1, characterized in that, In general formula I, x is an integer between 80 and 100.

3. The low-foaming oil agent according to claim 1, characterized in that, In general formula II, q is an integer between 80 and 100.

4. The low-foaming oil agent according to claim 1, characterized in that, The Z - Selected from halide ions, NO3 - CH3COO - and (SO4) 1 / 2 - .

5. The low-foaming oil agent according to claim 1, characterized in that, The surfactant is a composite surfactant comprising polyoxyethylene polyol ester and polyglycerol fatty acid ester.

6. The low-foaming oil agent according to claim 5, characterized in that, The polyoxyethylene polyol ester is selected from at least one of polyoxyethylene polyol esters with an HLB value of 9-16.

7. The low-foaming oil agent according to claim 6, characterized in that, The polyoxyethylene polyol ester is selected from Tween-81 and Tween-40.

8. The low-foaming oil agent according to claim 5, characterized in that, The polyglycerol fatty acid ester is selected from at least one of polyglycerol fatty acid esters with an HLB value of 2-8.

9. The low-foaming oil agent according to claim 8, characterized in that, The polyglycerol fatty acid esters mentioned above are selected from diglycerol oleate and triglycerol monooleate.

10. The low-foaming oil agent according to claim 5, characterized in that, The molar ratio of the polyoxyethylene polyol ester to the polyglycerol fatty acid ester is 0.1:1-10:

1.

11. The low-foaming oil agent according to claim 10, characterized in that, The molar ratio of the polyoxyethylene polyol ester to the polyglycerol fatty acid ester is 0.1:1 to 1:

1.

12. The low-foaming oil agent according to any one of claims 1-11, characterized in that, The polyol is selected from at least one of glycerol, trimethylolpropane, pentaerythritol, mannitol and sorbitol.

13. A method for preparing a low-foaming oiling agent for the production of PAN-based carbon fiber according to any one of claims 1 to 12, characterized in that, Includes the following steps: (1) The surfactant is mixed with side-chain amino-modified polysiloxane and quaternary ammonium-modified polyether polysiloxane to obtain mixture A; (2) Polyol and water are mixed to obtain mixture B; (3) Mix mixture B into mixture A.

14. The preparation method according to claim 13, characterized in that, In step (3), the temperature of the mixture is 40~60℃; and / or the mixing process is carried out under stirring and / or shearing conditions.

15. The preparation method according to claim 14, characterized in that, The stirring rate is 50~500 r / min, the stirring time is 2-5 h, and / or the shearing rate is 1000~20000 r / min, the shearing time is 1~4 h.

16. The preparation method according to any one of claims 13-15, characterized in that, The composite surfactant, the side-chain amino-modified polysiloxane, the quaternary ammonium-modified polyether polysiloxane, and the polyol are the active ingredients, and the active ingredients account for 10-30% of the total weight of the active ingredients and water.

Images