Low-temperature carbonized fiber body and low-temperature carbonization treatment method

Abstract

The invention provides a low-temperature carbonized fiber body and a low-temperature carbonization treatment method, and relates to the technical field of carbon fibers, the low-temperature carbonized fiber body has a linear density of 778-787g / km, a volume density of 1.625-1.635 g / cm < 3 >, an elastic modulus of greater than 43.5 GPa, an orientation degree of 67-68.5%, a skin layer proportion of a skin-core structure of greater than 90%, a carbon content of 68.5-70.5%, and a sediment proportion of less than 0.08%; wherein the low-temperature carbonized fiber body is obtained by performing low-temperature carbonization treatment on a polyacrylonitrile-based pre-oxidized fiber body by adopting an inclined horizontal type low-temperature carbonization furnace; wherein the polyacrylonitrile-based pre-oxidized fiber body is obtained by carrying out pre-oxidation treatment on a dry-jet wet-process polyacrylonitrile precursor with the monofilament diameter of 5-6 [mu] m. According to the invention, the low-temperature carbonized fiber body with excellent performance is provided as an evaluation standard, so that the carbon fiber with the strength mean value reaching 6348MPa (the strength reaches the standard when the strength is 5880MPa or above), the CV value being 2.32% and the linear density being controlled within the range of 515 + / -8g / cm < 3 > can be prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon fiber, and in particular relates to a low-temperature carbonized fiber body and a low-temperature carbonization treatment method. Background Art

[0002] Carbonization is the process of carbon fiber structure formation. After the carbonization process, the chain-like heat-resistant trapezoidal structure of the pre-oxidized polyacrylonitrile fiber is transformed into a turbostratic graphite structure. The carbonization process is divided into low-temperature carbonization (300-800°C) and high-temperature carbonization (1000-1600°C) according to the temperature range of the carbonization treatment. The low-temperature carbonization process mainly undergoes thermal cracking reactions, and non-carbon elements are removed to form a large amount of waste gas. During the low-temperature carbonization process, the fiber weight loss ratio can reach about 30-40%, and a large amount of waste gas is generated. It is necessary to deal with the waste discharge problem through reasonable process design and equipment design. In addition, the low-temperature carbonization process design and the matching with the process equipment will affect the formation of defects such as pores and sediments in the fiber microstructure. These defects will be inherited to the structure of the final carbon fiber, thereby affecting the performance of the carbon fiber.

[0003] At present, the commonly used low-temperature carbonization furnace is a horizontal furnace. In recent years, the newly emerged vertical low-temperature carbonization furnace has unique advantages in solving the waste discharge problem of low-temperature carbonization. It also has the advantages of small footprint and easy control of the protective gas flow field atmosphere in the furnace, and has gradually realized engineering application. However, the chimney effect of the gas in the vertical low-temperature carbonization furnace is too strong (the temperature in the low-temperature carbonization furnace can usually reach 700-800℃). In order to ensure the inert atmosphere state in the low-temperature carbonization furnace (low-temperature carbonization requires an inert nitrogen atmosphere, and oxygen entering will cause the tow to burn out), while increasing the nitrogen consumption, it is also necessary to limit the space of the muffle cavity in the low-carbon furnace, especially the gas sealing area at the inlet and outlet, which is easy to cause the hair to be blocked at the inlet or outlet, resulting in the running tow being broken. The blocked hair is also difficult to clean, affecting the operating stability and output of carbon fiber production. In order to combine the advantages of horizontal furnaces and vertical furnaces, an inclined horizontal low-temperature carbonization furnace with an inclination angle is designed.

[0004] The dry-jet wet spinning process is a new trend in the development of carbon fiber technology. Dry-jet wet spinning can achieve faster spinning speeds and higher production capacity, significantly reducing the cost of carbon fiber production, and is more suitable for large-scale, low-cost industrial production than wet spinning. The inclined horizontal low-temperature carbonization furnace can effectively handle the outstanding low-temperature carbonization waste discharge and foreign body jamming problems in the high-capacity carbon fiber production process, so this type of furnace is more suitable for dry-jet wet carbon fiber production.

[0005] Since the operation status and waste discharge of dry-spray wet-process polyacrylonitrile preoxidized fiber in low-temperature carbonization furnace are significantly different from those of traditional wet process, the waste discharge, protective gas atmosphere and flow field, tension and draft matching of inclined horizontal low-temperature carbonization furnace are also quite different from those of horizontal low-temperature carbonization furnace. Therefore, there are at least the following problems in the process of low-temperature carbonization of dry-spray wet-process polyacrylonitrile preoxidized fiber in inclined horizontal low-temperature carbonization furnace:

[0006] Related processes for low-temperature carbonization treatment of dry-spray wet-process polyacrylonitrile pre-oxidized fiber bodies using inclined horizontal low-temperature carbonization furnace equipment: At present, there is no evaluation standard for low-temperature carbonized fiber bodies to prepare carbon fibers with excellent performance. Furthermore, there is currently no corresponding low-temperature carbonization treatment process to prepare low-temperature carbonized fiber bodies with excellent performance that can be used as evaluation standards. Summary of the invention

[0007] Therefore, the present invention provides a low-temperature carbonized fiber body and a method for low-temperature carbonization treatment. The main purpose is to provide a low-temperature carbonized fiber body with excellent performance as an evaluation standard for the low-temperature carbonization treatment of dry-spray wet polyacrylonitrile pre-oxidized fiber body using an inclined horizontal low-temperature carbonization furnace equipment, so as to prepare carbon fibers with excellent performance.

[0008] In order to solve the above problems, the present invention provides a low-temperature carbonized fiber body, wherein the linear density of the low-temperature carbonized fiber body is 778-787 g / km and the bulk density is 1.625-1.635 g / cm 3 , elastic modulus> 43.5GPa, orientation degree of 67-68.5%, skin ratio of skin-core structure> 90%, carbon content of 68.5-70.5%, sediment ratio less than 0.08%;

[0009] The low-temperature carbonized fiber body is obtained by subjecting a polyacrylonitrile-based pre-oxidized fiber body to low-temperature carbonization treatment in an inclined horizontal low-temperature carbonization furnace;

[0010] The polyacrylonitrile-based preoxidized fiber body is obtained by preoxidation treatment of dry-spray wet-process polyacrylonitrile raw fibers with a single fiber diameter of 5 to 6 μm.

[0011] On the other hand, the present invention provides a low-temperature carbonization method, which is used to prepare the above-mentioned low-temperature carbonized fiber body; wherein the low-temperature carbonization method comprises the following steps:

[0012] The polyacrylonitrile-based pre-oxidized fiber body is sequentially passed through eight temperature zones in an inclined horizontal low-temperature carbonization furnace for low-temperature carbonization treatment to obtain a low-temperature carbonized fiber body; wherein the eight temperature zones are sequentially a first temperature zone, a second temperature zone, a third temperature zone, a fourth temperature zone, a fifth temperature zone, a sixth temperature zone, a seventh temperature zone and an eighth temperature zone; preferably, the temperature of the fifth temperature zone is lower than the temperature of the fourth temperature zone;

[0013] Among them, the weight loss ratio of the fiber in a single temperature zone from the first temperature zone to the fourth temperature zone is 4.5-5.6%, and the weight loss ratio of the fiber in a single temperature zone from the sixth temperature zone to the seventh temperature zone is 2-2.8%;

[0014] During the low-temperature carbonization process, the tension F per unit fiber fineness K It is 68~71.5cN.

[0015] Furthermore, the tension F per unit fineness of the fiber K Controlled by the temperature of the first temperature zone, the temperature of the eighth temperature zone, and the total draft ratio of the entire low-temperature carbonization process; and / or

[0016] The linear density of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone, the total draft ratio of the entire low-temperature carbonization process, and the fiber's own gravity; and / or

[0017] The bulk density of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone and the temperature gradient settings of the eight temperature zones; and / or

[0018] The modulus and orientation of the low-temperature carbonized fiber body are controlled by the total draft ratio of the entire low-temperature carbonization process and the fiber's own gravity; and / or

[0019] The skin ratio of the skin-core structure of the low-temperature carbonized fiber body is controlled by the temperature of the first temperature zone; and / or

[0020] The carbon content of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone, the temperature of the fourth temperature zone, and the temperature of the fifth temperature zone; and / or

[0021] The deposition ratio of the low-temperature carbonized fiber body is controlled by the temperature of the fourth temperature zone and the temperature of the fifth temperature zone; and / or

[0022] The weight loss ratio of the fiber in a single temperature zone is controlled by the temperature gradient settings of the eight temperature zones.

[0023] Further, during the low-temperature carbonization treatment: the temperature of the first temperature zone is 395-405°C; the temperature of the second temperature zone is 455-465°C; the temperature of the third temperature zone is 505-515°C; the temperature of the fourth temperature zone is 545-555°C; the temperature of the fifth temperature zone is 495-505°C; the temperature of the sixth temperature zone is 645-655°C; the temperature of the seventh temperature zone is 695-705°C; the temperature of the eighth temperature zone is 735-745°C; and / or

[0024] The total drawing rate of the entire low-temperature carbonization process is 0.45% to 0.55%.

[0025] Furthermore, the tension per unit fineness F K The calculation formula is as follows:

[0026]

[0027] In the formula, G1 is the total gravity of the fibers in the first to fourth temperature zones, G2 is the total gravity of the fibers in the fifth to eighth temperature zones, Q is the total drawing rate of the entire low-temperature carbonization treatment process, L1 is the linear density of the pre-oxidized fiber body, and L2 is the linear density of the low-temperature carbonized fiber obtained after the pre-oxidized fiber body is subjected to low-temperature carbonization treatment without drawing effect.

[0028] Furthermore, the waste outlet of the inclined horizontal low-temperature carbonization furnace is arranged in the fourth temperature zone.

[0029] Furthermore, the protective gas in the low-temperature carbonization treatment is nitrogen.

[0030] On the other hand, the present invention provides a polyacrylonitrile-based carbon fiber, characterized in that the polyacrylonitrile-based carbon fiber is obtained by subjecting a low-temperature carbonized fiber body to a high-temperature carbonization treatment; wherein the low-temperature carbonized fiber body is the above-mentioned low-temperature carbonized fiber body.

[0031] Further, the low-temperature carbonized fiber body is subjected to high-temperature carbonization treatment in ten temperature zones, and the temperatures in the ten temperature zones are 855-865°C, 935-945°C, 1095-1105°C, 1225-1235°C, 1335-1345°C, 1445-1455°C, 1445-1455°C, 1445-1455°C, 1365-1375°C, and 1205-1215°C, respectively; and / or

[0032] The total draft rate during the entire high temperature carbonization process is -2.8% to -2.6%; and / or

[0033] The waste discharge flow rate of the high temperature carbonization treatment is 355-365m 3 / h.

[0034] Furthermore, the strength of the polyacrylonitrile-based carbon fiber is ≥6000MPa, the strength CV value is ≤5%, and the linear density is 515±8g / cm 3 .

[0035] The low-temperature carbonized fiber body and the low-temperature carbonization treatment method provided by the present invention have the following beneficial effects:

[0036] 1. The present invention provides a low-temperature carbonized fiber body for a process of low-temperature carbonization treatment of a dry-spray wet-process polyacrylonitrile pre-oxidized fiber body using an inclined horizontal low-temperature carbonization furnace. Specifically, the low-temperature carbonized fiber body has a linear density of 778 to 787 g / km and a bulk density of 1.625 to 1.635 g / cm 3 , modulus>43.5GPa, orientation degree is 67-68.5%, skin ratio of skin-core structure>90%, carbon content is 68.5-70.5%, and sediment ratio is less than 0.08%. Here, the low-temperature carbonized fiber body can be used as an evaluation standard. As long as the linear density, bulk density, modulus, orientation degree, skin ratio of skin-core structure, carbon content and sediment ratio of the low-temperature carbonized fiber body meet the above conditions, the average strength of the carbon fiber product can be prepared to reach 6348MPa (strength above 5880MPa is up to standard), the strength CV value is 2.32%, and the linear density is controlled at 515±8g / cm 3 within the range.

[0037] 2. On the other hand, the present application provides a low-temperature carbonization treatment method, which mainly controls the parameters of the temperature zone to prepare the above-mentioned low-temperature carbonized fiber body; wherein the tension F per unit fineness of the fiber K The temperature of the first temperature zone, the temperature of the eighth temperature zone, the total draft ratio of the entire low-temperature carbonization process, and the fiber's own gravity are controlled; the linear density of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone, the total draft ratio of the entire low-temperature carbonization process, and the fiber's own gravity; the body density of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone and the temperature gradient setting of the eight temperature zones; the modulus and orientation degree of the low-temperature carbonized fiber body are controlled by the total draft ratio of the entire low-temperature carbonization process and the fiber's own gravity; the skin ratio of the skin-core structure of the low-temperature carbonized fiber body is controlled by the temperature of the first temperature zone; the carbon content of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone, the temperature of the fourth temperature zone, and the temperature of the fifth temperature zone; the sediment ratio of the low-temperature carbonized fiber body is controlled by the temperature of the fourth temperature zone and the temperature of the fifth temperature zone; the weight loss ratio of the fiber in a single temperature zone is controlled by the temperature gradient setting of the eight temperature zones;

[0038] The specific controls include: the temperature in the first temperature zone is 400°C; the temperature in the second temperature zone is 460°C; the temperature in the third temperature zone is 510°C; the temperature in the fourth temperature zone is 550°C; the temperature in the fifth temperature zone is 500°C; the temperature in the sixth temperature zone is 650°C; the temperature in the seventh temperature zone is 700°C; the temperature in the eighth temperature zone is 740°C; the total drawing rate in the entire low-temperature carbonization process is 0.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0040] Figure 1 This is a thermogravimetric-differential scanning calorimetric analysis result diagram of the pre-oxidized fiber body in the present invention. DETAILED DESCRIPTION

[0041] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0042] The present invention proposes a low-temperature carbonized fiber body and a method for low-temperature carbonization treatment. The present invention mainly conducts a large amount of research on the dry-jet wet spinning process combined with an inclined low-temperature carbonization process, proposes comprehensive evaluation indicators for low-temperature carbonized fiber bodies, and influencing factors of the evaluation indicators, and proposes corresponding low-temperature carbonization methods to guide the adjustment of the multi-temperature zone low-temperature carbonization process state, and regulate the operating state of carbon fiber production and the performance of the product.

[0043] The present invention uses an inclined horizontal low-temperature carbonization furnace (the angle between the path of the carbon fiber bundle in the inclined horizontal low-temperature carbonization furnace and the horizontal plane is 40-50°) with 8 independent gradient temperature zones (the length of the fiber heat treatment cavity in each temperature zone is 75 cm) for low-temperature carbonization treatment. Each temperature zone has an independent heating and temperature control system. The pre-oxidized fiber body is subjected to low-temperature carbonization treatment in 8 temperature zones in sequence from the bottom of the inclined horizontal low-temperature carbonization furnace to obtain a low-temperature carbonized fiber body. The exhaust port of the inclined horizontal low-temperature carbonization furnace is set in the fourth temperature zone. The low-temperature carbonization furnace uses nitrogen as a protective gas, gas seal and exhaust gas carrier.

[0044] The present invention provides a low-temperature carbonized fiber body, wherein the linear density of the low-temperature carbonized fiber body is 778-787 g / km and the bulk density is 1.625-1.635 g / cm3 , elastic modulus> 43.5GPa, orientation degree of 67-68.5%, skin ratio of skin-core structure> 90%, carbon content of 68.5-70.5%, sediment ratio less than 0.08%;

[0045] The low-temperature carbonized fiber body is obtained by subjecting the polyacrylonitrile-based pre-oxidized fiber body to low-temperature carbonization treatment in an inclined horizontal low-temperature carbonization furnace;

[0046] The polyacrylonitrile-based preoxidized fiber body is obtained by preoxidation treatment of dry-spray wet-process polyacrylonitrile raw silk with a single-filament diameter of 5 to 6 μm.

[0047] The skin ratio of the skin-core structure refers to the ratio of the skin thickness to the diameter of the low-temperature carbonized fiber body; the sediment ratio refers to the ratio of the mass of the sediment to the total mass of the low-temperature carbonized fiber body; the known components of the sediment include various short-chain hydrocarbons produced by low-temperature carbonization pyrolysis, and other complex products produced by the reaction of oil and fiber. These sediments will have a negative impact on the fiber during the subsequent high-temperature carbonization process. The sediment ratio is obtained by evaporation and weighing after acetone immersion extraction.

[0048] For the above-mentioned low-temperature carbonized fiber body, the linear density of the low-temperature carbonized fiber body affects the linear density of the carbon fiber; the bulk density affects the bulk density and yield of the carbon fiber; the modulus affects the modulus and strength of the carbon fiber; the orientation degree affects the modulus and strength of the carbon fiber; the cortex ratio affects the strength of the carbon fiber; the carbon content affects the broken strand rate and the carbon fiber yield and fluff in the low-temperature carbonization and high-temperature carbonization processes; the sediment ratio affects the broken strand rate and the strength, strength discreteness and fluff of the carbon fiber in the high-temperature carbonization process.

[0049] On the other hand, the present invention provides a low-temperature carbonization method, which is used to prepare the above-mentioned low-temperature carbonized fiber body; wherein the low-temperature carbonization method comprises the following steps:

[0050] The polyacrylonitrile-based preoxidized fiber body is sequentially passed through eight temperature zones in an inclined horizontal low-temperature carbonization furnace for low-temperature carbonization treatment to obtain a low-temperature carbonized fiber body;

[0051] Among them, the eight temperature zones are the first temperature zone, the second temperature zone, the third temperature zone, the fourth temperature zone, the fifth temperature zone, the sixth temperature zone, the seventh temperature zone and the eighth temperature zone;

[0052] Among them, the weight loss ratio of the fiber in a single temperature zone from the first temperature zone to the fourth temperature zone is 4.5-5.6%, and the weight loss ratio of the fiber in a single temperature zone from the sixth temperature zone to the seventh temperature zone is 2-2.8%;

[0053] During the low-temperature carbonization process, the tension F per unit fiber fineness K(K average tension) is 68-71.5 cN;

[0054] Tension F per unit fiber fineness K (K average tension, i.e. the ratio of the tension of the running filament bundle to the fineness) affects the broken strand rate and the carbon fiber hairiness, modulus, strength, and strength discreteness during the low-temperature carbonization and high-temperature carbonization processes; the weight loss ratio of the fiber in a single temperature zone affects the broken strand rate and the carbon fiber bulk density, strength, and strength discreteness during the low-temperature carbonization and high-temperature carbonization processes.

[0055] Furthermore, the tension per unit fiber fineness F K It is controlled by the temperature of the first temperature zone, the temperature of the eighth temperature zone, and the total draft rate of the entire low-temperature carbonization process; wherein the total draft rate of the entire low-temperature carbonization process is related to the fiber's own gravity;

[0056] The linear density of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone, the total draft ratio of the entire low-temperature carbonization process, and the fiber's own gravity;

[0057] The bulk density of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone and the temperature gradient settings of the eight temperature zones;

[0058] The modulus and orientation of the low-temperature carbonized fiber are controlled by the total draft ratio of the entire low-temperature carbonization process and the fiber's own gravity;

[0059] The skin ratio of the skin-core structure of the low-temperature carbonized fiber body is controlled by the temperature of the first temperature zone;

[0060] The carbon content of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone, the temperature of the fourth temperature zone, and the temperature of the fifth temperature zone;

[0061] The deposition ratio of the low-temperature carbonized fiber body is controlled by the temperature of the fourth temperature zone and the temperature of the fifth temperature zone;

[0062] The weight loss ratio of the fibers in a single temperature zone (including the weight loss ratio of the fibers in a single temperature zone from the first temperature zone to the fourth temperature zone, and the weight loss ratio of the fibers in a single temperature zone from the sixth temperature zone to the seventh temperature zone) is controlled by the temperature gradient settings of the eight temperature zones (the temperatures of the eight temperature zones).

[0063] Furthermore, during the low-temperature carbonization treatment: the temperature of the first temperature zone is 395-405°C; the temperature of the second temperature zone is 455-465°C; the temperature of the third temperature zone is 505-515°C; the temperature of the fourth temperature zone is 545-555°C; the temperature of the fifth temperature zone is 495-505°C; the temperature of the sixth temperature zone is 645-655°C; the temperature of the seventh temperature zone is 695-705°C; the temperature of the eighth temperature zone is 735-745°C; the total drawing rate of the entire low-temperature carbonization treatment process is 0.45%-0.55%.

[0064] Furthermore, the tension per unit fineness F K The calculation formula is as follows:

[0065]

[0066] The above formula is the tension F per unit fineness. K The empirical formula for process control is as follows: G1 is the total weight of the fibers in the first to fourth temperature zones, G2 is the total weight of the fibers in the fifth to eighth temperature zones, Q is the drafting control value, L1 is the linear density of the pre-oxidized fiber body, and L2 is the linear density of the low-temperature carbonized fiber obtained after the pre-oxidized fiber body is subjected to low-temperature carbonization treatment without drafting. The pre-oxidized fiber body is folded (the folded part is almost unaffected by the drafting), tied to a normally operating tow, and then measured after low-temperature carbonization treatment.

[0067] Furthermore, the waste outlet of the inclined horizontal low-temperature carbonization furnace is arranged in the fourth temperature zone.

[0068] Furthermore, the protective gas in the low-temperature carbonization treatment is nitrogen.

[0069] In another aspect, the present invention provides a polyacrylonitrile-based carbon fiber, which is obtained by subjecting a low-temperature carbonized fiber body to high-temperature carbonization treatment; wherein the low-temperature carbonized fiber body is the above-mentioned low-temperature carbonized fiber body.

[0070] The low-temperature carbonized fiber body is subjected to high-temperature carbonization treatment in ten temperature zones, and the temperatures of the ten temperature zones are 855-865°C, 935-945°C, 1095-1105°C, 1225-1235°C, 1335-1345°C, 1445-1455°C, 1445-1455°C, 1445-1455°C, 1365-1375°C, and 1205-1215°C, respectively; the total drawing rate of the entire high-temperature carbonization treatment process is -2.8% to -2.6%; the exhaust flow rate of the high-temperature carbonization treatment is 355-365m 3 / h.

[0071] Furthermore, the strength of the polyacrylonitrile-based carbon fiber is ≥6000MPa, the strength CV value is ≤5%, and the linear density is 515±8g / cm 3 .

[0072] Furthermore, the present invention uses a thermogravimetric-differential scanning calorimeter (TG-DSC) to analyze the dry-spray wet pre-oxidized fiber body used in the present invention under an argon protective atmosphere, with a heating rate of 20K / min. The TG-DSC analysis results are as follows: Figure 1 shown.

[0073] from Figure 1It can be seen that the DSC curve has an endothermic peak at about 126°C, and the corresponding TG curve has a weight loss of about 5%, which is caused by the evaporation of a small amount of water contained in the pre-oxidized fiber. The DSC curve has an exothermic peak at about 390°C. Referring to the existing research results, it should be the further oxidation cyclization reaction of the pre-oxidized fiber with the small amount of oxygen carried in the fiber under an inert atmosphere. The TG curve continues to lose weight violently in the range of 360-523°C, and the corresponding DSC curve begins to slowly release heat after 424°C, and there is a smaller exothermic peak at about 540°C, corresponding to the process of violent fiber cracking and weight loss in the low-temperature carbonization process. In the range of 540-762°C, the fiber weight loss and reaction heat release are further slowed down. After 762°C, an endothermic reaction occurs, and the DSC curve has an endothermic peak at about 826°C, and the corresponding TG curve weight loss accelerates. This temperature range corresponds to the initial polycondensation reaction of the fiber.

[0074] Combining the above analysis and test results, the temperature of the lowest temperature zone is determined according to the exothermic peak of the DSC curve at about 390°C, the temperature of the highest temperature zone is determined according to the endothermic reaction of the DSC curve and the TG curve at 760-826°C, and the temperature of the maximum waste discharge zone is determined according to the weight loss peak of the TG curve at about 523°C.

[0075] At the same time, the present invention combines the waste discharge characteristics of the inclined horizontal low-temperature carbonization furnace and the test results to set the temperature of the fifth temperature zone to be slightly lower than the temperature of the fourth temperature zone to ensure a better waste discharge effect.

[0076] The present invention conducts experiments and summarizes the reaction intensity of dry-wet-jet fibers in two temperature ranges of 390-530°C and 600-730°C. The experiment in the range of 390-530°C is for pre-oxidized fibers treated at 150°C, and the experiment in the range of 600-730°C is for pre-oxidized fibers treated at 550°C. The reaction intensity index corresponding to different low-temperature carbonization treatment temperatures is shown in Tables 1 and 2.

[0077] Table 1

[0078]

[0079] Table 2

[0080]

[0081] The equivalent treatment time at different low-temperature carbonization treatment temperatures can be converted according to the reaction severity index. Assuming that the equivalent residence time at low-temperature carbonization treatment temperatures T1 and T2 are t1 and t2 respectively, the corresponding reaction severity index is K T1 , K T2 , the conversion formula is as follows:

[0082]

[0083] According to the reaction intensity, it can be converted to equivalent low-temperature carbonization treatment time of 400℃ (before the maximum waste discharge area) and 600℃ (after the maximum waste discharge area).

[0084] Before the maximum waste discharge zone (including the maximum waste discharge zone itself, the present invention corresponds to the first temperature zone to the fourth temperature zone), the total equivalent 400°C treatment time range should be 155-159s; after the maximum waste discharge zone (excluding the airflow blockage zone after the maximum waste discharge zone, the present invention corresponds to the sixth temperature zone to the eighth temperature zone), the total equivalent 600°C treatment time range should be 76-80s.

[0085] According to the above-determined temperature of the lowest low temperature zone, the temperature of the highest high temperature zone, the temperature of the maximum waste discharge temperature zone and the temperature after the maximum waste discharge temperature zone (the fifth temperature zone for this application), combined with the above-mentioned low-temperature carbonization treatment time at 400°C and 600°C, it is determined that the temperatures of the eight temperature zones in the entire low-temperature carbonization treatment process of this application are preferably: the temperature of the first temperature zone is 400°C; the temperature of the second temperature zone is 460°C; the temperature of the third temperature zone is 510°C; the temperature of the fourth temperature zone is 550°C; the temperature of the fifth temperature zone is 500°C; the temperature of the sixth temperature zone is 650°C; the temperature of the seventh temperature zone is 700°C; and the temperature of the eighth temperature zone is 740°C.

[0086] Furthermore, the present invention proposes a tension control method for an inclined horizontal low-temperature carbonization furnace suitable for dry-spray wet carbon fiber. The fibers are affected by their own gravity during the treatment process in the inclined horizontal low-temperature carbonization furnace. The present invention uses the total weight of the fibers from the entrance drive roller of the inclined horizontal low-temperature carbonization furnace to the fourth temperature zone of the low-temperature carbonization furnace as the first-stage gravity G1, and the total weight of the fibers from the fifth temperature zone of the low-temperature carbonization furnace to the exit drive roller as the second-stage gravity G2. The draft control value is Q, the linear density of the pre-oxidized fiber body is L1, and the linear density of the low-temperature carbonized fiber obtained by low-temperature carbonization treatment of the pre-oxidized fiber body without drafting is L2. After experimental summary, the present invention obtains the average tension F K The relationship with fiber gravity and draft control value is as follows:

[0087]

[0088] The present invention is further described below by specific examples and comparative examples:

[0089] Example 1

[0090] This embodiment provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first to eighth temperature zones of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C respectively;

[0091] Among them, the total draft rate of the entire low-temperature carbonization process is 0.5%; the K average tension during the low-temperature carbonization operation is 70.41cN, and the strand breakage rate is 0; the subsequent high-temperature carbonization process has a strand breakage rate of 0;

[0092] Among them, the first stage gravity (the total gravity of the fibers in the first temperature zone to the fourth temperature zone) G1 is 3.348 cN, the second stage gravity (the total gravity of the fibers in the fifth temperature zone to the eighth temperature zone) G2 is 3.062 cN, the linear density L1 of the pre-oxidized fiber body is 1050 g / km, and the linear density L2 of the low-temperature carbonized fiber body obtained by low-temperature carbonization treatment of the pre-oxidized fiber body without drawing is 799 g / km; the weight loss ratios of fibers in the first temperature zone, the second temperature zone, the third temperature zone, the fourth temperature zone, the sixth temperature zone, and the seventh temperature zone are 5.33%, 5.36%, 5.21%, 4.71%, 2.39%, and 2.33%, respectively.

[0093] The linear density of the low-temperature carbonized fiber prepared in this embodiment is 781 g / km and the bulk density is 1.632 g / cm 3 , the elastic modulus is 44.4GPa, the strength is 1036MPa, the orientation degree is 67.8%, the skin-core structure cortex ratio is 91.4%, the carbon content is 69.7%, and the sediment ratio is 0.04%.

[0094] The low-temperature carbonized fiber body is subjected to high-temperature carbonization treatment in ten temperature zones to obtain polyacrylonitrile-based carbon fibers; wherein the temperatures of the ten temperature zones are 860°C, 940°C, 1100°C, 1230°C, 1340°C, 1450°C, 1450°C, 1450°C, 1370°C, and 1210°C, respectively; the total drawing rate of the entire high-temperature carbonization treatment process is -2.7%; the waste discharge flow rate of the high-temperature carbonization treatment is 360m 3 / h.

[0095] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this embodiment has a strength of 6348 MPa, a strength test CV (strength CV value) of 2.32%, an elastic modulus of 309 GPa, a hairiness of 0.45, and a bulk density of 1.805 g / cm 3 , linear density is 516g / km, and yield is 51.38%.

[0096] In the following comparative examples, the obtained low-temperature carbonized fiber body is subjected to high-temperature carbonization treatment in ten temperature zones to obtain polyacrylonitrile-based carbon fibers; wherein the process and parameters of the high-temperature carbonization treatment are the same as those in Example 1.

[0097] Comparative Example 1

[0098] This comparative example is a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a slanted low-temperature carbonization furnace is used to perform carbonization treatment in 8 temperature zones to obtain a low-temperature carbonized fiber body. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 625°C, 675°C, and 720°C respectively;

[0099] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 68.5 cN, and the strand breakage rate is 0; the subsequent high-temperature carbonization process has a strand breakage rate of 0.

[0100] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 776 g / km and a bulk density of 1.619 g / cm 3 , the elastic modulus is 45.2GPa, the strength is 1025MPa, the orientation degree is 66.8%, the skin-core structure cortex ratio is 91.2%, the carbon content is 67.5%, and the sediment ratio is 0.05%.

[0101] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6232MPa, a strength test CV of 2.45%, an elastic modulus of 297GPa, a hairiness of 0.31, and a bulk density of 1.801g / cm 3 , linear density is 509g / km, and yield is 49.84%.

[0102] Comparative Example 2

[0103] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body of dry-wet-jet raw silk with a single-filament diameter of 5 to 6 μm and a single-filament number of 12,000, a slanted low-temperature carbonization furnace is used to perform carbonization treatment in 8 temperature zones to obtain a low-temperature carbonized fiber body. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 600°C, 655°C, and 700°C, respectively;

[0104] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 68.92cN, and the strand breakage rate is 0; the subsequent high-temperature carbonization process has a strand breakage rate of 0.

[0105] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 774 g / km, and the bulk density is 1.623 g / cm 3 , the elastic modulus is 44.9GPa, the strength is 1034MPa, the orientation degree is 67.2%, the skin-core structure cortex ratio is 91.8%, the carbon content is 67.3%, and the sediment ratio is 0.04%.

[0106] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6284 MPa, a strength test CV of 3.11%, an elastic modulus of 305 GPa, a hairiness of 1, and a bulk density of 1.799 g / cm 3 , linear density is 511g / km, and yield is 49.77%.

[0107] Comparative Example 3

[0108] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 585°C, 630°C, and 680°C, respectively.

[0109] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 67.92cN, and the strand breakage rate is 0.01; the subsequent high-temperature carbonization process has a strand breakage rate of 0.01.

[0110] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 770 g / km and a bulk density of 1.601 g / cm 3 , the elastic modulus is 43.8GPa, the strength is 1045MPa, the orientation degree is 67.4%, the skin-core structure cortex ratio is 90.9%, the carbon content is 66.9%, and the sediment ratio is 0.04%.

[0111] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6115 MPa, a strength test CV of 3.04%, an elastic modulus of 298 GPa, a hairiness of 0.54, and a bulk density of 1.792 g / cm 3 , linear density is 504g / km, and yield is 48.33%.

[0112] Comparative Example 4

[0113] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body of dry-jet wet-jet raw silk with a single-filament diameter of 5 to 6 μm and a single-filament number of 12,000, a carbonization treatment is performed in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace to obtain a low-temperature carbonized fiber body. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 565°C, 615°C, and 660°C, respectively.

[0114] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 67.75 cN, and the strand breakage rate is 0; the subsequent high-temperature carbonization process has a strand breakage rate of 0.

[0115] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 769 g / km and a bulk density of 1.597 g / cm 3 , the elastic modulus is 44.6GPa, the strength is 989MPa, the orientation degree is 66.5%, the skin-core structure cortex ratio is 91.5%, the carbon content is 66.5%, and the sediment ratio is 0.05%.

[0116] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6148 MPa, a strength test CV of 2.79%, an elastic modulus of 307 GPa, a hairiness of 1.07, and a bulk density of 1.788 g / cm 3 , linear density is 507g / km, and yield is 48.52%.

[0117] Comparative Example 5

[0118] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 665°C, 715°C, and 760°C, respectively.

[0119] The total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 70.92cN, and the strand breakage rate is 0.44; the strand breakage rate in the subsequent high-temperature carbonization process is 0.56.

[0120] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 790 g / km and the bulk density is 1.644 g / cm 3, the elastic modulus is 45.4GPa, the strength is 945MPa, the orientation degree is 68.2%, the skin-core structure cortex ratio is 91.4%, the carbon content is 70.5%, and the sediment ratio is 0.04%.

[0121] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5762MPa, a strength test CV of 5.2%, an elastic modulus of 304GPa, a hairiness of 2.79, and a bulk density of 1.81g / cm 3 , linear density is 520g / km, and yield is 52.33%.

[0122] Comparative Example 6

[0123] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 680°C, 735°C, and 780°C, respectively.

[0124] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 71.58 cN, and the strand breakage rate is 0.49; the subsequent high-temperature carbonization process has a strand breakage rate of 0.63.

[0125] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 788 g / km and a bulk density of 1.645 g / cm 3 , the elastic modulus is 44.9GPa, the strength is 912MPa, the orientation degree is 68.1%, the skin-core structure cortex ratio is 91.7%, the carbon content is 70.4%, and the sediment ratio is 0.04%.

[0126] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5833 MPa, a strength test CV of 4.99%, an elastic modulus of 309 GPa, a hairiness of 3.11, and a bulk density of 1.809 g / cm 3 , linear density is 521g / km, and yield is 52.46%.

[0127] Comparative Example 7

[0128] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 695°C, 760°C, and 800°C, respectively.

[0129] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 71.75cN, and the strand breakage rate is 1.34; the subsequent high-temperature carbonization process has a strand breakage rate of 2.12.

[0130] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 794 g / km and a bulk density of 1.65 g / cm 3 , the elastic modulus is 46.2GPa, the strength is 1004MPa, the orientation degree is 68%, the skin-core structure cortex ratio is 91%, the carbon content is 71.5%, and the sediment ratio is 0.04%.

[0131] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5455 MPa, a strength test CV of 7.55%, an elastic modulus of 306 GPa, a hairiness of 7.37, and a bulk density of 1.811 g / cm 3 , linear density is 523g / km, and yield is 52.79%.

[0132] Comparative Example 8

[0133] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 710°C, 780°C, and 820°C, respectively.

[0134] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 71.67cN, and the strand breakage rate is 1.65; the strand breakage rate in the subsequent high-temperature carbonization process is 2.44.

[0135] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 797 g / km and a bulk density of 1.649 g / cm 3, the elastic modulus is 46.5GPa, the strength is 934MPa, the orientation degree is 67.7%, the skin-core structure cortex ratio is 91.8%, the carbon content is 71.2%, and the sediment ratio is 0.04%.

[0136] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5367 MPa, a strength test CV of 8.31%, an elastic modulus of 305 GPa, a hairiness of 6.11, and a bulk density of 1.807 g / cm 3 , linear density is 521g / km, and yield is 52.91%.

[0137] Comparative Example 9

[0138] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 370°C, 440°C, 500°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively.

[0139] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 70.83 cN, and the strand breakage rate is 0; the subsequent high-temperature carbonization process has a strand breakage rate of 0.

[0140] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 782 g / km and a bulk density of 1.63 g / cm 3 , the elastic modulus is 44.6GPa, the strength is 936MPa, the orientation degree is 67.6%, the skin-core structure cortex ratio is 87.7%, the carbon content is 70%, and the sediment ratio is 0.04%.

[0141] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5888 MPa, a strength test CV of 2.74%, an elastic modulus of 300 GPa, a hairiness of 0.64, and a bulk density of 1.794 g / cm 3 , linear density is 509g / km, and yield is 51.39%.

[0142] Comparative Example 10

[0143] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 350°C, 425°C, 485°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively.

[0144] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 70.83 cN, and the strand breakage rate is 0; the subsequent high-temperature carbonization process has a strand breakage rate of 0.

[0145] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 779 g / km and the bulk density is 1.632 g / cm 3 , the elastic modulus is 44.6GPa, the strength is 928MPa, the orientation degree is 67.6%, the skin-core structure skin ratio is 86.9%, the carbon content is 69.7%, and the sediment ratio is 0.04%.

[0146] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5812 MPa, a strength test CV of 2.65%, an elastic modulus of 299 GPa, a hairiness of 1.09, and a bulk density of 1.796 g / cm 3 , linear density is 507g / km, and yield is 51.43%.

[0147] Comparative Example 11

[0148] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 350°C, 425°C, 485°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively.

[0149] The total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 70 cN, and the strand breakage rate is 0; and the strand breakage rate during the subsequent high-temperature carbonization process is 0.

[0150] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 781 g / km and the bulk density is 1.636 g / cm 3 , the elastic modulus is 44.4GPa, the strength is 901MPa, the orientation degree is 68%, the skin-core structure cortex ratio is 83.1%, the carbon content is 70.1%, and the sediment ratio is 0.05%.

[0151] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5432MPa, a strength test CV of 3.32%, an elastic modulus of 298GPa, a hairiness of 0.85, and a bulk density of 1.788g / cm 3 , linear density is 501g / km, and yield is 51.5%.

[0152] Comparative Example 12

[0153] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 310°C, 385°C, 450°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively.

[0154] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 70.75cN, and the strand breakage rate is 0.01; the subsequent high-temperature carbonization process has a strand breakage rate of 0.01.

[0155] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 780 g / km and the bulk density is 1.632 g / cm 3 , the elastic modulus is 44.1GPa, the strength is 887MPa, the orientation degree is 67.4%, the skin-core structure cortex ratio is 82.7%, the carbon content is 69.5%, and the sediment ratio is 0.05%.

[0156] The strength of the carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example is 5311MPa, the strength test CV is 4.17%, the elastic modulus is 300GPa, the hairiness is 0.41, the bulk density is 1.785g / cm3, the linear density is 503g / km, and the yield is 51.23%.

[0157] Comparative Example 13

[0158] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 440°C, 4460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively.

[0159] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%; the K average tension during the low-temperature carbonization operation is 70.083cN, and the strand breakage rate is 0.55; the subsequent high-temperature carbonization process has a strand breakage rate of 0.69.

[0160] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 785 g / km and a bulk density of 1.629 g / cm 3 , the elastic modulus is 44.3GPa, the strength is 932MPa, the orientation degree is 0.679, the skin-core structure cortex ratio is 0.916, the carbon content is 0.699, and the sediment ratio is 0.0005.

[0161] The strength of the carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example is 5910MPa, the strength test CV is 0.0434, the elastic modulus is 298GPa, the hairiness is 3.41, the bulk density is 1.803g / cm3, the linear density is 517g / km, and the yield is 0.513.

[0162] Comparative Example 14

[0163] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 460°C, 485°C, 520°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively.

[0164] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%, the average tension of the low-temperature carbonization operation process is 70.83cN, and the strand breakage rate is 0.63; the strand breakage rate of the subsequent high-temperature carbonization process is 0.7.

[0165] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 785 g / km and the bulk density is 1.631 g / cm 3 , the elastic modulus is 44.8GPa, the strength is 971MPa, the orientation degree is 67.4%, the skin-core structure cortex ratio is 91.6%, the carbon content is 69.7%, and the sediment ratio is 0.03%.

[0166] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5831 MPa, a strength test CV of 4.59%, an elastic modulus of 303 GPa, a hairiness of 3.19, and a bulk density of 1.81 g / cm 3 , linear density is 510g / km, and yield is 51.23%.

[0167] Comparative Example 15

[0168] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 480°C, 500°C, 525°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0169] Among them, the average tension of K in the low-temperature carbonization process was 70.58 cN, and the strand breakage rate was 0.97; the strand breakage rate in the subsequent high-temperature carbonization process was 1.22.

[0170] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 778 g / km and the bulk density is 1.637 g / cm 3 , the elastic modulus is 43.9GPa, the strength is 869MPa, the orientation degree is 67.6%, the skin-core structure cortex ratio is 91.1%, the carbon content is 69.6%, and the sediment ratio is 0.05%.

[0171] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5633 MPa, a strength test CV of 6.78%, an elastic modulus of 304 GPa, a hairiness of 4.29, and a bulk density of 1.804 g / cm 3 , linear density is 511g / km, and yield is 51.31%.

[0172] Comparative Example 16

[0173] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first to eighth temperature zones of the low-temperature carbonization furnace are 500°C, 525°C, 530°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively;

[0174] Among them, the total drawing rate of the entire low-temperature carbonization treatment is 0.5%, the average tension of the low-temperature carbonization operation process is 70.17 cN, and the strand breakage rate is 1.01; the strand breakage rate of the subsequent high-temperature carbonization process is 1.59.

[0175] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 785 g / km and the bulk density is 1.635 g / cm 3, the elastic modulus is 44GPa, the strength is 904MPa, the orientation degree is 67.5%, the skin-core structure cortex ratio is 91.6%, the carbon content is 69.8%, and the sediment ratio is 0.03%.

[0176] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5545 MPa, a strength test CV of 6.99%, an elastic modulus of 308 GPa, a hairiness of 5.34, and a bulk density of 1.805 g / cm 3 , linear density is 512g / km, and yield is 51.11%.

[0177] Comparative Example 17

[0178] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 510°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0179] Among them, the average tension K in the low-temperature carbonization process was 70.33 cN, and the strand breakage rate was 0.02; the strand breakage rate in the subsequent high-temperature carbonization process was 0.23.

[0180] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 784 g / km, and the bulk density is 1.637 g / cm 3 , the elastic modulus is 45.2GPa, the strength is 876MPa, the orientation degree is 67.5%, the skin-core structure cortex ratio is 91.1%, the carbon content is 66.7%, and the sediment ratio is 0.27%.

[0181] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5632MPa, a strength test CV of 7.54%, an elastic modulus of 303GPa, a hairiness of 1.88, and a bulk density of 1.802g / cm 3 , linear density is 520g / km, and yield is 51.35%.

[0182] Comparative Example 18

[0183] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 490°C, 490°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0184] Among them, the average tension of K in the low-temperature carbonization process is 70cN, and the strand breakage rate is 0.01; the strand breakage rate in the subsequent high-temperature carbonization process is 0.57.

[0185] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 784 g / km and a bulk density of 1.635 g / cm 3 , the elastic modulus is 43.8GPa, the strength is 891MPa, the orientation degree is 67.8%, the skin-core structure cortex ratio is 91.7%, the carbon content is 65.4%, and the sediment ratio is 0.33%.

[0186] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5571 MPa, a strength test CV of 8.12%, an elastic modulus of 306 GPa, a hairiness of 3.02, and a bulk density of 1.809 g / cm 3 , linear density is 519 g / km, and yield is 51.19%.

[0187] Comparative Example 19

[0188] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 580°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0189] Among them, the average tension K in the low-temperature carbonization process was 70.67 cN, and the strand breakage rate was 0; the strand breakage rate in the subsequent high-temperature carbonization process was 0.12.

[0190] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 779 g / km, and the bulk density is 1.631 g / cm 3 , the elastic modulus is 44.8GPa, the strength is 901MPa, the orientation degree is 68.2%, the skin-core structure cortex ratio is 91.1%, the carbon content is 70.5%, and the sediment ratio is 0.11%.

[0191] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5701 MPa, a strength test CV of 7.69%, an elastic modulus of 300 GPa, a hairiness of 1.48, and a bulk density of 1.791 g / cm 3 , linear density is 511g / km, and yield is 51.14%.

[0192] Comparative Example 20

[0193] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 600°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0194] Among them, the average tension of K in the low-temperature carbonization process is 70cN, and the strand breakage rate is 0.03; the strand breakage rate in the subsequent high-temperature carbonization process is 0.15.

[0195] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 780 g / km and a bulk density of 1.636 g / cm 3 , the elastic modulus is 44.6GPa, the strength is 937MPa, the orientation degree is 68.2%, the skin-core structure cortex ratio is 91.4%, the carbon content is 69.8%, and the sediment ratio is 0.09%.

[0196] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5494 MPa, a strength test CV of 9.31%, an elastic modulus of 297 GPa, a hairiness of 1.79, and a bulk density of 1.787 g / cm 3 , linear density is 516 g / km, and yield is 51.36%.

[0197] Comparative Example 21

[0198] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 520°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0199] Among them, the average tension K in the low-temperature carbonization process was 70.25 cN, and the strand breakage rate was 0; the strand breakage rate in the subsequent high-temperature carbonization process was 0.05.

[0200] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 781 g / km and the bulk density is 1.637 g / cm 3 , the elastic modulus is 44.5GPa, the strength is 994MPa, the orientation degree is 68.2%, the skin-core structure cortex ratio is 91.8%, the carbon content is 69.6%, and the sediment ratio is 0.08%.

[0201] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6148 MPa, a strength test CV of 3.45%, an elastic modulus of 307 GPa, a hairiness of 1.94, and a bulk density of 1.808 g / cm 3 , linear density is 516 g / km, and yield is 51.14%.

[0202] Comparative Example 22

[0203] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 550°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0204] Among them, the average tension of K in the low-temperature carbonization process was 70.83 cN, and the strand breakage rate was 0.01; the strand breakage rate in the subsequent high-temperature carbonization process was 0.14.

[0205] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 778 g / km and the bulk density is 1.635 g / cm 3 , the elastic modulus is 44.4GPa, the strength is 936MPa, the orientation degree is 68%, the skin-core structure cortex ratio is 91.5%, the carbon content is 68.1%, and the sediment ratio is 0.22%.

[0206] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5895 MPa, a strength test CV of 4.21%, an elastic modulus of 303 GPa, a hairiness of 2.34, and a bulk density of 1.81 g / cm 3 , linear density is 517g / km, and yield is 51.15%.

[0207] Comparative Example 23

[0208] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 580°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0209] Among them, the average tension of K in the low-temperature carbonization process was 70.83 cN, and the strand breakage rate was 0.01; the strand breakage rate in the subsequent high-temperature carbonization process was 0.49.

[0210] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 776 g / km and the bulk density is 1.627 g / cm 3 , the elastic modulus is 44.7GPa, the strength is 945MPa, the orientation degree is 67.9%, the skin-core structure cortex ratio is 91.8%, the carbon content is 67.6%, and the sediment ratio is 0.34%.

[0211] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5734 MPa, a strength test CV of 5.34%, an elastic modulus of 300 GPa, a hairiness of 3.45, and a bulk density of 1.808 g / cm 3 , linear density is 519 g / km, and yield is 51.35%.

[0212] Comparative Example 24

[0213] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 600°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0214] Among them, the average tension of K in the low-temperature carbonization process was 70.42 cN, and the strand breakage rate was 0.02; the strand breakage rate in the subsequent high-temperature carbonization process was 0.56.

[0215] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 783 g / km, and the bulk density is 1.634 g / cm 3, the elastic modulus is 44.8GPa, the strength is 909MPa, the orientation degree is 68.2%, the skin-core structure cortex ratio is 91.6%, the carbon content is 66.9%, and the sediment ratio is 0.37%.

[0216] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5628 MPa, a strength test CV of 6.92%, an elastic modulus of 298 GPa, a hairiness of 4.13, and a bulk density of 1.805 g / cm 3 , linear density is 516g / km, and yield is 51.31%.

[0217] Comparative Example 25

[0218] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.3%.

[0219] Among them, the average tension of K in the low-temperature carbonization process is 66cN, and the strand breakage rate is 0.01; the strand breakage rate in the subsequent high-temperature carbonization process is 0.

[0220] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 792 g / km and a bulk density of 1.63 g / cm 3 , the elastic modulus is 41.5GPa, the strength is 975MPa, the orientation degree is 66.9%, the skin-core structure cortex ratio is 91.6%, the carbon content is 69.8%, and the sediment ratio is 0.04%.

[0221] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6101 MPa, a strength test CV of 2.88%, an elastic modulus of 293 GPa, a hairiness of 0.87, and a bulk density of 1.808 g / cm 3 , linear density is 519 g / km, and yield is 51.17%.

[0222] Comparative Example 26

[0223] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.1%.

[0224] Among them, the average tension of K in the low-temperature carbonization process is 63.67 cN, and the strand breakage rate is 0; the strand breakage rate in the subsequent high-temperature carbonization process is 0.

[0225] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 799 g / km and the bulk density is 1.634 g / cm 3 , the elastic modulus is 39.7GPa, the strength is 964MPa, the orientation degree is 65.7%, the skin-core structure cortex ratio is 91.1%, the carbon content is 69.6%, and the sediment ratio is 0.03%.

[0226] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5931 MPa, a strength test CV of 2.18%, an elastic modulus of 290 GPa, a hairiness of 0.55, and a bulk density of 1.801 g / cm 3 , linear density is 524g / km, and yield is 51.42%.

[0227] Comparative Example 27

[0228] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is -0.2%.

[0229] Among them, the average tension K in the low-temperature carbonization process was 58.67 cN, and the strand breakage rate was 0; the strand breakage rate in the subsequent high-temperature carbonization process was 0.01.

[0230] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 804 g / km and the bulk density is 1.634 g / cm 3 , the elastic modulus is 37.7GPa, the strength is 915MPa, the orientation degree is 65.1%, the skin-core structure cortex ratio is 91.3%, the carbon content is 69.6%, and the sediment ratio is 0.04%.

[0231] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5765 MPa, a strength test CV of 3.05%, an elastic modulus of 284 GPa, a hairiness of 0.68, and a bulk density of 1.805 g / cm 3 , linear density is 527g / km, and yield is 51.17%.

[0232] Comparative Example 28

[0233] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is -0.5%.

[0234] Among them, the average tension of K in the low-temperature carbonization process was 54.5cN, and the strand breakage rate was 0.02; the strand breakage rate in the subsequent high-temperature carbonization process was 0.02.

[0235] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 808 g / km and the bulk density is 1.637 g / cm 3 , the elastic modulus is 35.2GPa, the strength is 934MPa, the orientation degree is 64.5%, the skin-core structure cortex ratio is 91.2%, the carbon content is 70%, and the sediment ratio is 0.04%.

[0236] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5684 MPa, a strength test CV of 3.39%, an elastic modulus of 280 GPa, a hairiness of 0.49, and a bulk density of 1.808 g / cm 3 , linear density is 530g / km, and yield is 51.35%.

[0237] Comparative Example 29

[0238] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is -1%.

[0239] Among them, the average tension of K in the low-temperature carbonization process was 48.25 cN, and the strand breakage rate was 0.01; the strand breakage rate in the subsequent high-temperature carbonization process was 0.01.

[0240] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 823 g / km and a bulk density of 1.63 g / cm 3 , the elastic modulus is 34.4GPa, the strength is 879MPa, the orientation degree is 63.8%, the skin-core structure cortex ratio is 91.8%, the carbon content is 69.8%, and the sediment ratio is 0.05%.

[0241] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5594 MPa, a strength test CV of 2.96%, an elastic modulus of 275 GPa, a hairiness of 0.42, and a bulk density of 1.809 g / cm 3 , linear density is 539 g / km, and yield is 51.1%.

[0242] Comparative Example 30

[0243] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.7%.

[0244] Among them, the average tension of K in the low-temperature carbonization process was 74.5cN, and the strand breakage rate was 0.03; the strand breakage rate in the subsequent high-temperature carbonization process was 0.07.

[0245] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 789 g / km and a bulk density of 1.627 g / cm 3 , the elastic modulus is 45.1GPa, the strength is 1045MPa, the orientation degree is 67.9%, the skin-core structure cortex ratio is 91.5%, the carbon content is 70.1%, and the sediment ratio is 0.04%.

[0246] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6379 MPa, a strength test CV of 2.49%, an elastic modulus of 310 GPa, a hairiness of 1.11, and a bulk density of 1.804 g / cm 3 , linear density is 512g / km, and yield is 51.25%.

[0247] Comparative Example 31

[0248] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.1%.

[0249] Among them, the average tension of K in the low-temperature carbonization process was 80.83 cN, and the strand breakage rate was 0.14; the strand breakage rate in the subsequent high-temperature carbonization process was 0.24.

[0250] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 783 g / km and the bulk density is 1.635 g / cm 3 , the elastic modulus is 45.3GPa, the strength is 1018MPa, the orientation degree is 68.1%, the skin-core structure cortex ratio is 91.2%, the carbon content is 69.6%, and the sediment ratio is 0.04%.

[0251] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6298 MPa, a strength test CV of 3.02%, an elastic modulus of 308 GPa, a hairiness of 1.97, and a bulk density of 1.804 g / cm 3 , linear density is 509g / km, and yield is 51.31%.

[0252] Comparative Example 32

[0253] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 1.3%.

[0254] Among them, the average tension of K in the low-temperature carbonization process was 88.42 cN, and the strand breakage rate was 0.45; the strand breakage rate in the subsequent high-temperature carbonization process was 0.91.

[0255] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 778 g / km and a bulk density of 1.628 g / cm 3, the elastic modulus is 45.7GPa, the strength is 1022MPa, the orientation degree is 68.3%, the skin-core structure cortex ratio is 91.2%, the carbon content is 69.8%, and the sediment ratio is 0.05%.

[0256] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6014 MPa, a strength test CV of 5.34%, an elastic modulus of 304 GPa, a hairiness of 3.21, and a bulk density of 1.806 g / cm 3 , linear density is 506g / km, and yield is 51.36%.

[0257] Comparative Example 33

[0258] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 1.8%.

[0259] Among them, the average tension of K in the low-temperature carbonization process was 103.58 cN, and the strand breakage rate was 2.24; the strand breakage rate in the subsequent high-temperature carbonization process was 5.38.

[0260] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 775 g / km and a bulk density of 1.637 g / cm 3 , the elastic modulus is 44.9GPa, the strength is 978MPa, the orientation degree is 67.8%, the skin-core structure cortex ratio is 91%, the carbon content is 69.9%, and the sediment ratio is 0.05%.

[0261] The strength of the carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example is 5431MPa, the strength test CV is 10.45%, the elastic modulus is 297GPa, the hairiness is 11.64, the bulk density is 1.8g / cm3, the linear density is 500g / km, and the yield is 51.13%.

[0262] Comparative Example 34

[0263] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 6000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0264] Among them, the average tension of K in the low-temperature carbonization process is 63.83 cN, and the strand breakage rate is 0.01; the strand breakage rate in the subsequent high-temperature carbonization process is 0.

[0265] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 798 g / km and the bulk density is 1.635 g / cm 3 , the elastic modulus is 40.1GPa, the strength is 959MPa, the orientation degree is 65.6%, the skin-core structure cortex ratio is 91.1%, the carbon content is 69.6%, and the sediment ratio is 0.03%.

[0266] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 5914 MPa, a strength test CV of 2.37%, an elastic modulus of 291 GPa, a hairiness of 0.55, and a bulk density of 1.801 g / cm 3 , the linear density is 523g / km, and the yield is 51.42%. The first stage gravity G1 is 1.675cN, the second stage gravity G2 is 1.53cN, the linear density L1 of the pre-oxidized fiber body is 529g / km, and the linear density L2 of the low-temperature carbonized fiber body obtained by low-temperature carbonization treatment of the pre-oxidized fiber body without drawing is 400g / km.

[0267] Comparative Example 35

[0268] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 6000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.08%.

[0269] Among them, the average tension of K in the low-temperature carbonization process is 69.5cN, and the strand breakage rate is 0.01; the strand breakage rate in the subsequent high-temperature carbonization process is 0.

[0270] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 780 g / km and a bulk density of 1.633 g / cm 3 , the elastic modulus is 44.3GPa, the strength is 1027MPa, the orientation degree is 67.9%, the skin-core structure cortex ratio is 91.2%, the carbon content is 69.7%, and the sediment ratio is 0.05%.

[0271] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6321 MPa, a strength test CV of 2.49%, an elastic modulus of 311 GPa, a hairiness of 0.58, and a bulk density of 1.804 g / cm 3 , the linear density is 519g / km, and the yield is 51.39%. The first stage gravity G1 is 1.675cN, the second stage gravity G2 is 1.53cN, the linear density L1 of the pre-oxidized fiber body is 529g / km, and the linear density L2 of the low-temperature carbonized fiber body obtained by low-temperature carbonization treatment of the pre-oxidized fiber body without drawing is 400g / km.

[0272] Comparative Example 36

[0273] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 3000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.8%.

[0274] Among them, the average tension of K in the low-temperature carbonization process is 65.33 cN, and the strand breakage rate is 0; the strand breakage rate in the subsequent high-temperature carbonization process is 0.

[0275] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 795 g / km and the bulk density is 1.634 g / cm 3 , the elastic modulus is 41.4GPa, the strength is 959MPa, the orientation degree is 65.6%, the skin-core structure cortex ratio is 91.2%, the carbon content is 69.7%, and the sediment ratio is 0.04%.

[0276] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6122MPa, a strength test CV of 2.94%, an elastic modulus of 294GPa, a hairiness of 0.78, and a bulk density of 1.804g / cm 3, linear density is 520g / km, yield is 51.41%. The first stage gravity G1 is 0.839cN, the second stage gravity G2 is 0.767cN, the linear density L1 of the pre-oxidized fiber body is 267g / km, and the linear density L2 of the low-temperature carbonized fiber body obtained by low-temperature carbonization treatment of the pre-oxidized fiber body without drawing is 198g / km.

[0277] Comparative Example 37

[0278] This comparative example provides a low-temperature carbonization treatment method, for a pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 300, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 1%.

[0279] Among them, the average tension of K in the low-temperature carbonization process is 70cN, and the strand breakage rate is 0; the strand breakage rate in the subsequent high-temperature carbonization process is 0.

[0280] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 781 g / km and a bulk density of 1.634 g / cm 3 , the elastic modulus is 45.1GPa, the strength is 1029MPa, the orientation degree is 67.6%, the skin-core structure cortex ratio is 91.3%, the carbon content is 69.8%, and the sediment ratio is 0.05%.

[0281] The carbon fiber prepared by the low-temperature carbonized fiber body prepared in this comparative example has a strength of 6297 MPa, a strength test CV of 2.99%, an elastic modulus of 307 GPa, a hairiness of 0.45, and a bulk density of 1.805 g / cm 3 , the linear density is 518g / km, and the yield is 51.44%. The first stage gravity G1 is 0.839cN, the second stage gravity G2 is 0.767cN, the linear density L1 of the pre-oxidized fiber body is 267g / km, and the linear density L2 of the low-temperature carbonized fiber body obtained by low-temperature carbonization treatment of the pre-oxidized fiber body without drawing is 198g / km.

[0282] Comparative Example 38

[0283] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0284] Among them, the average tension of K in the low-temperature carbonization process was 78.08 cN, and the strand breakage rate was 0.12; the strand breakage rate in the subsequent high-temperature carbonization process was 0.26.

[0285] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 780 g / km and the bulk density is 1.635 g / cm 3 , the elastic modulus is 45.2GPa, the strength is 1008MPa, the orientation degree is 68.2%, the skin-core structure cortex ratio is 91.2%, the carbon content is 69.6%, and the sediment ratio is 0.04%.

[0286] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6247 MPa, a strength test CV of 3.45%, an elastic modulus of 308 GPa, a hairiness of 1.86, and a bulk density of 1.804 g / cm 3 , linear density is 510g / km, yield is 51.31%. The first stage gravity G1 is 4.659cN, the second stage gravity G2 is 3.062cN, the linear density L1 of the pre-oxidized fiber body is 1050g / km, and the linear density L2 of the low-temperature carbonized fiber body obtained by low-temperature carbonization treatment of the pre-oxidized fiber body without drawing is 799g / km.

[0287] Comparative Example 39

[0288] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.1%.

[0289] Among them, the average tension of K in the low-temperature carbonization process is 70.67 cN, and the strand breakage rate is 0; the strand breakage rate in the subsequent high-temperature carbonization process is 0.

[0290] The linear density of the low-temperature carbonized fiber prepared in this comparative example is 780 g / km and the bulk density is 1.632 g / cm 3 , the elastic modulus is 44.7GPa, the strength is 1041MPa, the orientation degree is 67.5%, the skin-core structure cortex ratio is 91.3%, the carbon content is 69.8%, and the sediment ratio is 0.05%.

[0291] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6314 MPa, a strength test CV of 2.88%, an elastic modulus of 307 GPa, a hairiness of 0.37, and a bulk density of 1.802 g / cm 3 , the linear density is 517g / km, and the yield is 51.38%. The first stage gravity G1 is 4.659cN, the second stage gravity G2 is 3.062cN, the linear density L1 of the pre-oxidized fiber body is 1050g / km, and the linear density L2 of the low-temperature carbonized fiber body obtained by low-temperature carbonization treatment of the pre-oxidized fiber body without drawing is 799g / km.

[0292] Comparative Example 40

[0293] This comparative example provides a low-temperature carbonization treatment method, for the pre-oxidized fiber body after pre-oxidation treatment of dry-jet wet-jet raw silk with a single fiber diameter of 5 to 6 μm and a single fiber number of 12,000, a low-temperature carbonized fiber body is obtained by carbonizing in 8 temperature zones using an inclined horizontal low-temperature carbonization furnace. The temperatures of the first temperature zone to the eighth temperature zone of the low-temperature carbonization furnace are 400°C, 460°C, 510°C, 550°C, 500°C, 650°C, 700°C, and 740°C, respectively, and the total draft rate of the entire low-temperature carbonization treatment is 0.5%.

[0294] Among them, the average tension of K in the low-temperature carbonization process is 69.08 cN, and the strand breakage rate is 0; the strand breakage rate in the subsequent high-temperature carbonization process is 0.

[0295] The low-temperature carbonized fiber prepared in this comparative example has a linear density of 778 g / km and a bulk density of 1.634 g / cm 3 , the elastic modulus is 44.6GPa, the strength is 1043MPa, the orientation degree is 67.8%, the skin-core structure cortex ratio is 91.5%, the carbon content is 69.6%, and the sediment ratio is 0.04%.

[0296] The carbon fiber prepared by the low-temperature carbonized fiber body obtained in this comparative example has a strength of 6303 MPa, a strength test CV of 2.41%, an elastic modulus of 310 GPa, a hairiness of 0.75, and a bulk density of 1.803 g / cm 3, linear density is 518g / km, yield is 51.29. The first stage gravity G1 is 3.348cN, the second stage gravity G2 is 4.357cN, the linear density L1 of the pre-oxidized fiber body is 1050g / km, and the linear density L2 of the low-temperature carbonized fiber body obtained by low-temperature carbonization treatment of the pre-oxidized fiber body without drawing is 799g / km.

[0297] The present invention enriches the process control method and evaluation method of the low-temperature carbonization process, making it more in line with the actual process control of dry-jet wet carbon fiber. The present invention introduces the K average tension, broken strand rate and linear density, bulk density, modulus, strength, orientation, skin-core structure skin ratio, carbon content, sediment and other indicators of the low-temperature carbonization process of the dry-jet wet carbon fiber as evaluation indicators of the low-temperature carbonization process of the dry-jet wet carbon fiber, and clarifies the relationship between these indicators and the performance of the carbon fiber product.

[0298] Comparative Examples 1 to 4 (Comparative Example 1) have low carbon fiber yields due to low body density and carbon content of the low-temperature carbonized fiber body; Comparative Examples 9 to 12 (Comparative Example 1) have low strength of the finished carbon fiber, increased strength discreteness, and low body density due to the heavy skin-core structure of the low-temperature carbonized fiber body; Comparative Examples 17 to 24 (Comparative Example 1) have poor on-site operation status and low strength of the finished carbon fiber, increased strength discreteness, and high hairiness due to the excessively high proportion of low-temperature carbonized fiber deposits; Comparative Examples 25 to 29 (Comparative Example 1) have low K average tension during the low-temperature carbonization process and low bulk modulus, strength, and orientation of the low-temperature carbonized fiber, resulting in low carbon fiber strength and high linear density; Comparative Examples 30 to 33 (Comparative Example 1) have poor on-site operation status and low strength of the finished carbon fiber, increased strength discreteness, high hairiness, and low linear density due to the high K average tension during the low-temperature carbonization process and high bulk modulus and orientation of the low-temperature carbonized fiber.

[0299] In view of the above process indicators, the present invention summarizes the process control methods and related influencing factors of the corresponding indicators, which are suitable for the oblique low-temperature carbonization process debugging of dry-spray wet carbon fiber. For example: Comparative Examples 1 to 8 (Comparative Example 1) The influence of the highest treatment temperature on the linear density, bulk density, carbon content and production operation status of the low-temperature carbonized fiber body; Comparative Examples 9 to 16 (Comparative Example 1) The influence of the lowest treatment temperature on the linear density, bulk density, modulus, skin-core structure and production operation status of the low-temperature carbonized fiber body; Comparative Examples 17 to 20 (Comparative Example 1) The influence of the maximum waste discharge temperature (the temperature of the fourth temperature zone in the area where the waste discharge port is located) on the strength, sediment ratio and production operation status of the low-temperature carbonized fiber body; Comparative Examples 21 to 24 (Comparative Example 1) The influence of the 5th zone temperature on the strength, sediment ratio and production operation status of the low-temperature carbonized fiber body; Comparative Examples 25 to 33 (Comparative Example 1) The influence of the drafting value on the K-average tension of the low-temperature carbonization process and the linear density, modulus, strength, orientation degree and production operation status of the low-temperature carbonized fiber body;

[0300] According to the above-mentioned low-temperature carbonization process index system and control method, the present invention provides a process control method for low-temperature carbonization process of dry-wet spray carbon fiber inclined horizontal furnace with a monofilament diameter of 5 to 6 μm (i.e., Example 1), the average strength of the obtained carbon fiber finished product reaches 6348MPa (strength above 5880MPa is up to standard), the CV value is 2.32%, and the linear density is controlled at 515±8g / cm 3 within the range.

[0301] The present invention provides a correspondence between process temperature and reaction intensity in a low-temperature carbonization process. According to different reaction intensities at different process temperatures, the reaction speed and fiber weight loss ratio of multi-temperature zone carbonization treatment are regulated, thereby guiding the design of multi-temperature zone process temperature gradient of an inclined horizontal low-temperature carbonization furnace.

[0302] The present invention provides a method for controlling the tension of dry-wet-jet carbon fiber in an inclined horizontal low-temperature carbonization furnace. The reaction characteristics of dry-wet-jet preoxidized fiber, the fiber gravity factor in the inclined horizontal low-temperature carbonization furnace, and the influence of the process draft value are comprehensively considered, thereby guiding the tension control during the carbonization process of the inclined horizontal low-temperature carbonization furnace. Comparative Examples 34 to 37 change the number of fiber filaments, and Comparative Examples 38 to 40 change the segmented gravity, which are verified by comparing with Example 1.

[0303] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0304] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A low-temperature carbonized fiber body, characterized in that: The low-temperature carbonized fiber body has a linear density of 778-787 g / km and a bulk density of 1.625-1.635 g / cm 3 , elastic modulus> 43.5GPa, orientation degree of 67-68.5%, skin ratio of skin-core structure> 90%, carbon content of 68.5-70.5%, sediment ratio less than 0.08%; The low-temperature carbonized fiber body is obtained by subjecting a polyacrylonitrile-based pre-oxidized fiber body to low-temperature carbonization treatment in an inclined horizontal low-temperature carbonization furnace; The polyacrylonitrile-based preoxidized fiber body is obtained by preoxidation treatment of dry-spray wet-process polyacrylonitrile raw fibers with a single fiber diameter of 5 to 6 μm.

2. A low temperature carbonization treatment method, characterized in that: The low-temperature carbonization treatment method is used to prepare the low-temperature carbonized fiber body according to claim 1; wherein the low-temperature carbonization treatment method comprises the following steps: The polyacrylonitrile-based preoxidized fiber body is sequentially passed through eight temperature zones in an inclined horizontal low-temperature carbonization furnace for low-temperature carbonization treatment to obtain a low-temperature carbonized fiber body; The eight temperature zones are the first temperature zone, the second temperature zone, the third temperature zone, the fourth temperature zone, the fifth temperature zone, the sixth temperature zone, the seventh temperature zone and the eighth temperature zone in sequence; preferably, the temperature of the fifth temperature zone is lower than the temperature of the fourth temperature zone; Among them, the weight loss ratio of the fiber in a single temperature zone from the first temperature zone to the fourth temperature zone is 4.5-5.6%, and the weight loss ratio of the fiber in a single temperature zone from the sixth temperature zone to the seventh temperature zone is 2-2.8%; During the low-temperature carbonization process, the tension F per unit fiber fineness K It is 68~71.5cN.

3. The low temperature carbonization treatment method according to claim 2, characterized in that: The tension F per unit fineness of the fiber K Controlled by the temperature of the first temperature zone, the temperature of the eighth temperature zone, and the total draft ratio of the entire low-temperature carbonization process; and / or The linear density of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone, the total draft ratio of the entire low-temperature carbonization process, and the fiber's own gravity; and / or The bulk density of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone and the temperature gradient settings of the eight temperature zones; and / or The modulus and orientation of the low-temperature carbonized fiber body are controlled by the total draft ratio of the entire low-temperature carbonization process and the fiber's own gravity; and / or The skin ratio of the skin-core structure of the low-temperature carbonized fiber body is controlled by the temperature of the first temperature zone; and / or The carbon content of the low-temperature carbonized fiber body is controlled by the temperature of the eighth temperature zone, the temperature of the fourth temperature zone, and the temperature of the fifth temperature zone; and / or The deposition ratio of the low-temperature carbonized fiber body is controlled by the temperature of the fourth temperature zone and the temperature of the fifth temperature zone; and / or The weight loss ratio of the fiber in a single temperature zone is controlled by the temperature gradient settings of the eight temperature zones.

4. The low temperature carbonization method according to claim 3, characterized in that: During the low temperature carbonization treatment: the temperature of the first temperature zone is 395-405°C; the temperature of the second temperature zone is 455-465°C; the temperature of the third temperature zone is 505-515°C; the temperature of the fourth temperature zone is 545-555°C; the temperature of the fifth temperature zone is 495-505°C; the temperature of the sixth temperature zone is 645-655°C; the temperature of the seventh temperature zone is 695-705°C; the temperature of the eighth temperature zone is 735-745°C; and / or The total drawing rate of the entire low-temperature carbonization process is 0.45% to 0.55%.

5. The low-temperature carbonization method of polyacrylonitrile-based fiber according to any one of claims 2 to 4, characterized in that: Tension per unit fineness F K The calculation formula is as follows: In the formula, G1 is the total gravity of the fibers in the first to fourth temperature zones, G2 is the total gravity of the fibers in the fifth to eighth temperature zones, Q is the total drawing rate of the entire low-temperature carbonization treatment process, L1 is the linear density of the pre-oxidized fiber body, and L2 is the linear density of the low-temperature carbonized fiber obtained after the pre-oxidized fiber body is subjected to low-temperature carbonization treatment without drawing effect.

6. The low temperature carbonization method according to claim 2, characterized in that: The waste outlet of the inclined horizontal low-temperature carbonization furnace is arranged in the fourth temperature zone.

7. The low temperature carbonization method according to claim 2, characterized in that: The protective gas in the low temperature carbonization treatment is nitrogen.

8. A polyacrylonitrile-based carbon fiber, characterized in that: The polyacrylonitrile-based carbon fiber is obtained by subjecting a low-temperature carbonized fiber body to a high-temperature carbonization treatment; wherein the low-temperature carbonized fiber body is the low-temperature carbonized fiber body according to claim 1.

9. The polyacrylonitrile-based carbon fiber according to claim 8, characterized in that: Carrying out high-temperature carbonization treatment on the low-temperature carbonized fiber body in ten temperature zones, wherein the temperatures of the ten temperature zones are 855-865°C, 935-945°C, 1095-1105°C, 1225-1235°C, 1335-1345°C, 1445-1455°C, 1445-1455°C, 1445-1455°C, 1365-1375°C, 1205-1215°C in sequence; and / or The total draft rate during the entire high temperature carbonization process is -2.8% to -2.6%; and / or The waste discharge flow rate of the high temperature carbonization treatment is 355-365m 3 / h.

10. The polyacrylonitrile-based carbon fiber according to claim 8 or 9, characterized in that: The polyacrylonitrile-based carbon fiber has a strength of ≥6000 MPa, a strength CV value of ≤5%, and a linear density of 515±8 g / cm 3 .

Images