CN-122013331-A - Multi-field synergistic PBO high-speed liquid crystal spinning method

CN122013331ACN 122013331 ACN122013331 ACN 122013331ACN-122013331-A

Abstract

The invention belongs to the technical field of high-performance fiber manufacturing, and particularly provides a multi-field collaborative PBO high-speed liquid crystal spinning method, which aims to solve the technical problems of large fiber diameter discrete coefficient, poor strength consistency in batches and high yarn breakage rate in high-speed spinning and can realize high orientation of molecular chains and uniform regulation and control of surfaces. The method is characterized in that a homogenizing composite drafting flow field, a homogenizing gradient temperature field, a homogenizing gradient autogenous cutting field and a homogenizing pre-diffusion concentration field are applied in a spinning channel from an outlet of a spinning hole to an inlet of a coagulating bath, and the discrete coefficient (CV value) of the fiber diameter is less than or equal to 3.5 percent, the discrete coefficient of the strength in a batch is less than or equal to 7.0 percent, the breakage rate is less than or equal to 5 times per 100 kilograms through field strength sectional matching and discrete coefficient closed-loop control, so that the method is suitable for industrial continuous production, and the stability of the molding of the fiber subsequent composite material is remarkably improved.

Inventors

XIAO ZUOXU
ZHONG WEIHUA
DAI YONG
LIU QUN
LIU WEI
LIU ZONGFA
GUO CHENG
MENG ZHAORUI
PENG XIANYU
ZHANG DIANBO
ZHANG GENJIAN
LIANG CHEN
BAI JINWANG
CHEN XIANGDONG

Assignees

山东非金属材料研究所

Dates

Publication Date: 20260512
Application Date: 20260326

Claims (8)

1. A multi-field cooperative PBO high-speed liquid crystal spinning method is characterized by comprising the following specific steps: (1) Pretreatment of spinning dope Selecting raw materials, namely adopting PBO polyphosphoric acid liquid crystal solution with the intrinsic viscosity of 27-28 dl/g, and controlling the solid content to be 14-16%; controlling the temperature and viscosity of the material before the spinneret plate at 180-200 ℃; the spinneret plate is designed by adopting a spinneret orifice with the aperture of 0.25-0.35mm and the length-diameter ratio of 4-6, and the outlet is set to be 15 DEG cone angle open; (2) Multi-field cooperative regulation and control system Applying a homogenizing composite drafting flow field, a uniform temperature gradient temperature field, a uniform flow gradient autogenous cutting field and a homogenizing pre-diffusion concentration field in a spinning channel from an outlet of a spinning hole to an inlet of a coagulating bath, and reducing a diameter discrete coefficient, a strength discrete coefficient in a batch and a yarn breakage rate through field strength sectional matching and discrete coefficient closed-loop control; (3) Post-treatment process After the multi-field cooperative regulation and control of the tows are completed, the tows enter a coagulating bath, and the following post-treatment procedures are sequentially carried out to obtain the finished product PBO fiber: a coagulating bath is that deionized water is added into the coagulating bath to realize uniform coagulation; Multistage washing, namely, removing residual polyphosphoric acid through 2-stage countercurrent washing; sectional drying, namely 120-300 ℃ sectional drying, so as to avoid internal stress concentration and remove redundant water; winding, wherein the winding speed is synchronous with the spinning speed.
2. The multi-field cooperative PBO high-speed liquid crystal spinning method of claim 1, wherein the action mechanism of the homogenizing composite drafting flow field in the step (2) is a two-stage mechanism of slow shrinkage drafting and constant stretch ratio drafting, the drafting stress fluctuation is controlled to be less than or equal to 10%, the outlet shrinkage angle of a spinning hole is 15 degrees, and the staged distribution is as follows: the taper angle of 0-25cm to 15 DEG is opened to form a uniform shrinkage drafting field, so that when the stock solution is extruded from the straight cylinder sizing section of the spinneret orifice to the air section, the flow path is in continuous and stepless linear expanding transition, and further the uniform shrinkage drafting field is formed; 25-100cm, wherein the fluctuation of the rotating speed is controlled to be less than or equal to 0.3 percent, so that the ratio of the linear speed of the traction roller to the extrusion linear speed of the melt of the spinneret orifice is kept constant, and a constant stretching ratio is constructed.
3. The multi-field collaborative PBO high-speed liquid crystal spinning method according to claim 1, wherein the temperature gradient design of the uniform temperature gradient temperature field in the step (2) is that a 4-level temperature section, namely a high temperature uniform temperature field, a medium and low temperature uniform temperature field and a low temperature uniform temperature field, are arranged along a filament outlet path, and the corresponding temperatures of the four sections are 185-195 ℃, 160-170 ℃, 130-140 ℃ and 100-110 ℃ in sequence.
4. The multi-field collaborative PBO high-speed liquid crystal spinning method according to claim 1 or 3, wherein in the step (2), four sections are divided into four sections in the spinning channel, which correspond to a high temperature equalizing temperature field, a medium temperature equalizing temperature field and a low temperature equalizing temperature field respectively, a partition plate is arranged on the inner side of the channel between each region, through holes through which spinning trickles can pass are formed in the partition plate, air outlets/steam outlets are uniformly formed in the channel wall above the partition plate, an independent channel interlayer is arranged on the outer side of the channel above each air outlet/steam outlet, and four groups of channel interlayers are arranged on the outer sides of channels corresponding to the high temperature equalizing temperature field, the medium temperature equalizing temperature field and the low temperature equalizing temperature field respectively.
5. The multi-field cooperative PBO high-speed liquid crystal spinning method of claim 4, wherein in the step (2), each channel interlayer is provided with an independent air inlet, independent annular air-homogenizing cutters are respectively arranged at positions 5cm, 30cm, 55cm and 80cm away from the outlet of the spinning hole, the annular air-homogenizing cutters are a group of annular meshes arranged on the channel wall, air deflectors are arranged on the upper side and the lower side of the meshes on the inner side of the channel, and the included angle between the air deflectors and the channel is less than or equal to 8 degrees.
6. The multi-field cooperative PBO high-speed liquid crystal spinning method of claim 4, wherein the flow rates of the low flow rate autogenous cutting field, the medium and high flow rate autogenous cutting field and the high flow rate autogenous cutting field are controlled to be 4-6m/s, 7-10m/s, 12-16m/s and 18-22m/s along the filament outlet path sequentially by controlling the air inlet flow rates of different channel interlayers.
7. The multi-field cooperative PBO high-speed liquid crystal spinning method of claim 1, wherein in the step (2), the homogenizing pre-diffusion concentration field device is designed in such a way that circumferentially symmetrical steam injection devices are uniformly arranged on the corresponding channel walls of the middle-low temperature uniform temperature field and the low temperature uniform temperature field at a distance of 50-100cm from the outlet of the spinneret orifice to release phosphoric acid aqueous solution steam.
8. The multi-field collaborative PBO high-speed liquid crystal spinning method according to claim 7, wherein a high-concentration pre-diffusion field is arranged at 50-75cm, the corresponding concentration range is 60-70wt% phosphoric acid aqueous solution, the corresponding spraying amount of the phosphoric acid aqueous solution at the stage is 3000-5000mL/h, a low-concentration pre-diffusion field is arranged at 75-100cm, the corresponding concentration range is 20-30wt% phosphoric acid aqueous solution, and the corresponding spraying amount of the phosphoric acid aqueous solution at the stage is 3000-5000mL/h.

Description

Multi-field synergistic PBO high-speed liquid crystal spinning method Technical Field The invention relates to the technical field of high-performance fiber manufacturing, in particular to a multi-field collaborative PBO high-speed liquid crystal spinning method which can realize the regulation and control of high orientation of molecular chains and homogenization of surfaces. Background The PBO fiber is used as a high-performance organic fiber, has excellent performances of ultra-high strength, high modulus, high temperature resistance and the like, and is widely applied to the fields of aerospace, national defense and military industry, high-end composite materials and the like. In the PBO high-speed liquid crystal spinning process, the spinning channel from the outlet of the spinning hole to the inlet of the coagulating bath is a key period for molecular chain orientation, fiber size forming and strength forming. However, the prior art has the following problems: The traditional scheme lacks a regulation and control mechanism aiming at discrete coefficients, a single draft flow field is easy to cause local stress concentration, the temperature field and the autogenous cutting field are regulated and controlled unevenly, the discrete coefficient (CV value) of the fiber diameter is generally more than or equal to 5%, the discrete coefficient of the strength in batches is more than or equal to 10%, the performance consistency of a composite material product is seriously affected, the swing amplitude of tows is large (more than or equal to +/-2 mm), the curing rate is uneven and the stress fluctuates, the breakage rate in the production process is more than or equal to 9 times/100 kg, the industrial production efficiency is reduced, and the production cost is increased. In the prior art, a multi-field cooperative mechanism of focusing 'diameter consistency-strength stability-production continuity' is lacking, the three relations cannot be balanced synchronously in a wire outlet window, and the severe requirements of a high-end composite material on fiber core indexes are difficult to meet. Therefore, the inventors have studied to solve the above problems. Disclosure of Invention The invention provides a multi-field cooperative PBO high-speed liquid crystal spinning method, which can realize the regulation and control of high orientation of molecular chains and homogenization of surfaces, and does not adopt the regulation and control method of electric field, ultrasonic, magnetic field and micro-nano constraint, and aims to solve the technical problems of large fiber diameter discrete coefficient, poor strength consistency in batches and high yarn breakage rate in high-speed spinning (more than 200 m/min). In a spinning channel from an outlet of a spinning hole to an inlet of a coagulating bath, a homogenizing composite drafting flow field, a homogenizing gradient temperature field, a homogenizing gradient autogenous cutting field and a homogenizing pre-diffusion concentration field are applied, and the discrete coefficient (CV value) of the fiber diameter is less than or equal to 3.5%, the discrete coefficient of the strength in a batch is less than or equal to 7.0% and the breakage rate is less than or equal to 5 times/100 kg through field strength sectional matching and discrete coefficient closed-loop control, so that the method is suitable for industrial continuous production and obviously improves the stability of the molding of the subsequent composite material of the fiber. The specific technical scheme of the invention is as follows: a multi-field cooperative PBO high-speed liquid crystal spinning method comprises the following specific steps: (1) Pretreatment of spinning dope Selecting raw materials, namely adopting PBO polyphosphoric acid liquid crystal solution with the intrinsic viscosity of 27-28 dl/g, controlling the solid content to be 14-16%, and ensuring the stability of a liquid crystal phase; the temperature and viscosity are controlled, namely, the temperature of the material before the spinneret plate is precisely controlled to be 180-200 ℃ (fluctuation is less than or equal to +/-2 ℃), and size fluctuation caused by viscosity mutation is avoided; the spinneret plate design adopts a spinneret orifice with the aperture of 0.25-0.35mm and the length-diameter ratio of 4-6, and the outlet is provided with a 15-degree cone angle open design, namely the outlet of the spinneret orifice is a horn mouth, so that stress mutation caused by sharp edges is avoided; (2) Multi-field cooperative regulation and control system Applying a homogenizing composite drafting flow field, a uniform temperature gradient temperature field, a uniform flow gradient autogenous cutting field and a homogenizing pre-diffusion concentration field in a spinning channel from an outlet of a spinning hole to an inlet of a coagulating bath, and reducing a diameter discrete coefficient, a strength discrete coefficient in a batc